WorldWideScience

Sample records for constraining galaxy evolution

  1. The Origin of Stellar Species: constraining stellar evolution scenarios with Local Group galaxy surveys

    Science.gov (United States)

    Sarbadhicary, Sumit; Badenes, Carles; Chomiuk, Laura; Maldonado, Jessica; Caprioli, Damiano; Heger, Mairead; Huizenga, Daniel

    2018-01-01

    Our understanding of the progenitors of many stellar species, such as supernovae, massive and low-mass He-burning stars, is limited because of many poorly constrained aspects of stellar evolution theory. For my dissertation, I have focused on using Local Group galaxy surveys to constrain stellar evolution scenarios by measuring delay-time distributions (DTD). The DTD is the hypothetical occurrence rate of a stellar object per elapsed time after a brief burst of star formation. It is the measured distribution of timescales on which stars evolve, and therefore serves as a powerful observational constraint on theoretical progenitor models. The DTD can be measured from a survey of stellar objects and a set of star-formation histories of the host galaxy, and is particularly effective in the Local Group, where high-quality star-formation histories are available from resolved stellar populations. I am currently calculating a SN DTD with supernova remnants (SNRs) in order to provide the strongest constraints on the progenitors of thermonuclear and core-collapse supernovae. However, most SNRs do not have reliable age measurements and their evolution depends on the ambient environment. For this reason, I wrote a radio light curve model of an SNR population to extract the visibility times and rates of supernovae - crucial ingredients for the DTD - from an SNR survey. The model uses observational constraints on the local environments from multi-wavelength surveys, accounts for missing SNRs and employs the latest models of shock-driven particle acceleration. The final calculation of the SN DTD in the Local Group is awaiting completion of a systematic SNR catalog from deep radio-continuum images, now in preparation by a group led by Dr. Laura Chomiuk. I have also calculated DTDs for the LMC population of RR Lyrae and Cepheid variables, which serve as important distance calibrators and stellar population tracers. We find that Cepheids can have delay-times between 10 Myrs - 1 Gyr

  2. Chemical evolution of galaxies

    CERN Document Server

    Matteucci, Francesca

    2012-01-01

    The term “chemical evolution of galaxies” refers to the evolution of abundances of chemical species in galaxies, which is due to nuclear processes occurring in stars and to gas flows into and out of galaxies. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in different galaxies. The topic is approached in a didactical and logical manner via galaxy evolution models which are compared with observational results obtained in the last two decades: The reader is given an introduction to the concept of chemical abundances and learns about the main stellar populations in our Galaxy as well as about the classification of galaxy types and their main observables. In the core of the book, the construction and solution of chemical evolution models are discussed in detail, followed by descriptions and interpretations of observations of ...

  3. Galaxy formation and evolution

    CERN Document Server

    Mo, Houjun; White, Simon

    2010-01-01

    The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

  4. Galaxy evolution. Galactic paleontology.

    Science.gov (United States)

    Tolstoy, Eline

    2011-07-08

    Individual low-mass stars have very long lives, comparable to the age of the universe, and can thus be used to probe ancient star formation. At present, such stars can be identified and studied only in the Milky Way and in the very closest of our neighboring galaxies, which are predominantly small dwarf galaxies. These nearby ancient stars are a fossil record that can provide detailed information about the physical processes that dominated the epoch of galaxy formation and subsequent evolution.

  5. Dwarf spheroidal galaxies: Keystones of galaxy evolution

    Science.gov (United States)

    Gallagher, John S., III; Wyse, Rosemary F. G.

    1994-01-01

    Dwarf spheroidal galaxies are the most insignificant extragalactic stellar systems in terms of their visibility, but potentially very significant in terms of their role in the formation and evolution of much more luminous galaxies. We discuss the present observational data and their implications for theories of the formation and evolution of both dwarf and giant galaxies. The putative dark-matter content of these low-surface-brightness systems is of particular interest, as is their chemical evolution. Surveys for new dwarf spheroidals hidden behind the stars of our Galaxy and those which are not bound to giant galaxies may give new clues as to the origins of this unique class of galaxy.

  6. The era of synoptic galactic archeology: using HST and Chandra observations to constrain the evolution of elliptical galaxies through the spatial distribution of globular clusters and X-ray binaries.

    Science.gov (United States)

    D'Abrusco, Raffaele; Fabbiano, Giuseppina; Zezas, Andreas

    2017-01-01

    Most of the stellar mass observed today in early-type galaxies is thought to be due to merging and accretion of smaller companions, but the details of these processes are still poorly constrained. Globular clusters, visible from the center to the halo of galaxies, reflect the evolution of their host galaxy in their kinematic, photometric and spatial distributions. By characterizing the spatial distribution of the population of globular clusters extracted from archival HST data of some of the most massive elliptical galaxies in the local Universe with a novel statistical approach, we recently discovered that two-dimensional spatial structures at small radii are common (D’Abrusco et al. 2014a; 2014b; 2015). Such structures, not detectable from ground-based data, can be linked to events in the evolution of the host galaxy. Moreover, we devised an interpretative framework that, based on the form, area and number of globular clusters of such structures, infers the frequency of major mergers and the mass spectrum of the accreted companions.For some of the galaxies investigated, X-ray data from Chandra joint observing programs were also available. Our method, applied to the distribution of X-ray binaries, has revealed, at least in the case of two galaxies (D’Abrusco et al. 2014a; D’Abrusco et al.23014c) the existence of overdensities that are not associated to globular cluster structures. These findings provide complementary hints about the evolution of the stellar component of these galaxies that can be used to further refine the sequence of events that determined their growth.In this contribution, we will summarize our main results and highlight the novelty of our approach. Furthermore, we will advocate the fundamental importance of joint observations of galaxies by HST and Chandra as a way to provide unique, complementary views of such systems and unlock the mysteries of their evolution.

  7. The Galaxy Evolution Probe

    Science.gov (United States)

    Glenn, Jason; Galaxy Evolution Probe Team

    2018-01-01

    The Galaxy Evolution Probe (GEP) is a concept for a far-infrared observatory to survey large regions of sky for star-forming galaxies from z = 0 to beyond z = 3. Our knowledge of galaxy formation is incomplete and requires uniform surveys over a large range of redshifts and environments to accurately describe mass assembly, star formation, supermassive black hole growth, interactions between these processes, and what led to their decline from z ~ 2 to the present day. Infrared observations are sensitive to dusty, star-forming galaxies, which have bright polycyclic aromatic hydrocarbon (PAH) emission features and warm dust continuum in the rest-frame mid infrared and cooler thermal dust emission in the far infrared. Unlike previous far-infrared continuum surveys, the GEP will measure photometric redshifts commensurate with galaxy detections from PAH emission and Si absorption features, without the need for obtaining spectroscopic redshifts of faint counterparts at other wavelengths.The GEP design includes a 2 m diameter telescope actively cooled to 4 K and two instruments: (1) An imager covering 10 to 300 um with 25 spectral resolution R ~ 8 bands (with lower R at the longest wavelengths) to detect star-forming galaxies and measure their redshifts photometrically. (2) A 23 – 190 um, R ~ 250 dispersive spectrometer for redshift confirmation and identification of obscured AGN using atomic fine-structure lines. Lines including [Ne V], [O IV], [O III], [O I], and [C II] will probe gas physical conditions, radiation field hardness, and metallicity. Notionally, the GEP will have a two-year mission: galaxy surveys with photometric redshifts in the first year and a second year devoted to follow-up spectroscopy. A comprehensive picture of star formation in galaxies over the last 10 billion years will be assembled from cosmologically relevant volumes, spanning environments from field galaxies and groups, to protoclusters, to dense galaxy clusters.Commissioned by NASA, the

  8. Secular Evolution of Spiral Galaxies

    National Research Council Canada - National Science Library

    Zhang, Xiaolei

    2003-01-01

    It is now a well established fact that galaxies undergo significant morphological transformation during their lifetimes, manifesting as an evolution along the Hubble sequence from the late to the early Hubble types...

  9. Constraining Cosmic Evolution of Type Ia Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  10. Observing and Simulating Galaxy Evolution

    DEFF Research Database (Denmark)

    Olsen, Karen Pardos

    , but 50% smaller _CO factors, with the latter decreasing towards the center of each model galaxy. In a second study, SÍGAME is adapted to model the fine-structure line of singly ionized carbon, [CII] at 158 _m, the most powerful emission line of neutral ISM. Applying SÍGAME to the same type of galaxies......It remains a quest for modern astronomy to answer what main mechanisms set the star formation rate (SFR) of galaxies. Massive galaxies present a good starting point for such a quest due to their relatively easy detection at every redshift. Since stars form out of cold and dense gas, a comprehensive...... model for galaxy evolution should explain any observed connection between SFR and the amount and properties of the molecular gas of the interstellar medium (ISM). In proposed models of that kind, an active galactic nucleus (AGN) phase is often invoked as the cause for the decrease or cease of star...

  11. Secular Evolution in Disk Galaxies

    Science.gov (United States)

    Kormendy, John

    2013-10-01

    Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via the evolution processes that are available to them. They do this by spreading -- the inner parts shrink while the outer parts expand -- provided that some physical process efficiently transports energy or angular momentum outward. The reason is that self-gravitating systems have negative specific heats. As a result, the evolution of stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks and galaxy disks are fundamentally similar. How evolution proceeds then depends on the evolution processes that are available to each kind of self-gravitating system. These processes and their consequences for galaxy disks are the subjects of my lectures and of this Canary Islands Winter School. I begin with a review of the formation, growth and death of bars. Then I review the slow (`secular') rearrangement of energy, angular momentum, and mass that results from interactions between stars or gas clouds and collective phenomena such as bars, oval disks, spiral structure and triaxial dark haloes. The `existence-proof' phase of this work is largely over: we have a good heuristic understanding of how nonaxisymmetric structures rearrange disk gas into outer rings, inner rings and stuff dumped onto the centre. The results of simulations correspond closely to the morphology of barred and oval galaxies. Gas that is transported to small radii reaches high densities. Observations confirm that many barred and oval galaxies have dense central concentrations of gas and star formation. The result is to grow, on timescales of a few Gyr, dense central components that are frequently mistaken for classical (elliptical-galaxy-like) bulges but that were grown slowly out of the disk (not made rapidly by major mergers). The resulting picture of secular galaxy evolution accounts for the richness observed in galaxy structure. We can distinguish between classical and pseudo

  12. Do Galaxies Follow Darwinian Evolution?

    Science.gov (United States)

    2006-12-01

    Using VIMOS on ESO's Very Large Telescope, a team of French and Italian astronomers have shown the strong influence the environment exerts on the way galaxies form and evolve. The scientists have for the first time charted remote parts of the Universe, showing that the distribution of galaxies has considerably evolved with time, depending on the galaxies' immediate surroundings. This surprising discovery poses new challenges for theories of the formation and evolution of galaxies. The 'nature versus nurture' debate is a hot topic in human psychology. But astronomers too face similar conundrums, in particular when trying to solve a problem that goes to the very heart of cosmological theories: are the galaxies we see today simply the product of the primordial conditions in which they formed, or did experiences in the past change the path of their evolution? ESO PR Photo 17/06 ESO PR Photo 45/06 Galaxy Distribution in Space In a large, three-year long survey carried out with VIMOS [1], the Visible Imager and Multi-Object Spectrograph on ESO's VLT, astronomers studied more than 6,500 galaxies over a wide range of distances to investigate how their properties vary over different timescales, in different environments and for varying galaxy luminosities [2]. They were able to build an atlas of the Universe in three dimensions, going back more than 9 billion years. This new census reveals a surprising result. The colour-density relation, that describes the relationship between the properties of a galaxy and its environment, was markedly different 7 billion years ago. The astronomers thus found that the galaxies' luminosity, their initial genetic properties, and the environments they reside in have a profound impact on their evolution. "Our results indicate that environment is a key player in galaxy evolution, but there's no simple answer to the 'nature versus nurture' problem in galaxy evolution," said Olivier Le Fèvre from the Laboratoire d'Astrophysique de Marseille

  13. Constrained vertebrate evolution by pleiotropic genes

    DEFF Research Database (Denmark)

    Hu, Haiyang; Uesaka, Masahiro; Guo, Song

    2017-01-01

    Despite morphological diversification of chordates over 550 million years of evolution, their shared basic anatomical pattern (or 'bodyplan') remains conserved by unknown mechanisms. The developmental hourglass model attributes this to phylum-wide conserved, constrained organogenesis stages...

  14. Galaxy Evolution in Clusters Since z ~ 1

    Science.gov (United States)

    Aragón-Salamanca, A.

    Galaxy clusters provide some of the most extreme environments in which galaxies evolve, making them excellent laboratories to study the age old question of "nature" vs. "nurture" in galaxy evolution. Here I review some of the key observational results obtained during the last decade on the evolution of the morphology, structure, dynamics, star-formation history and stellar populations of cluster galaxies since the time when the Universe was half its present age. Many of the results presented here have been obtained within the ESO Distant Cluster Survey (EDisCS) and Space Telescope A901/02 Galaxy Evolution Survey (STAGES) collaborations.

  15. Evolution of the extinction curves in galaxies

    OpenAIRE

    Asano, Ryosuke S.; Takeuchi, Tsutomu T.; Hirashita, Hiroyuki; Nozawa, Takaya

    2014-01-01

    We investigate the evolution of extinction curves in galaxies based on our evolution model of grain size distribution. In this model, we considered various processes: dust formation by SNe II and AGB stars, dust destruction by SN shocks in the ISM, metal accretion onto the surface of grains (referred to as grain growth), shattering and coagulation. We find that the extinction curve is flat in the earliest stage of galaxy evolution. As the galaxy is enriched with dust, shattering becomes effec...

  16. The resolved history of galaxy evolution.

    Science.gov (United States)

    Brinchmann, Jarle

    2002-12-15

    We briefly review the study of the evolution of galaxies from an observational point of view, with particular emphasis on the role of the Hubble Space Telescope in probing the evolution of the different morphological types of galaxy. We show how using the stellar mass of galaxies as a tracer of evolution can improve our understanding of the physical process taking place before turning our eyes towards the future and giving an overview of what we can expect from future advances in technology.

  17. The extraordinary structural evolution of massive galaxies

    NARCIS (Netherlands)

    Szomoru, Daniel

    2013-01-01

    Galaxies have changed drastically over the past 10 billion years. This thesis deals with these changes, focusing on evolution in the structure of very massive galaxies with a range of stellar population properties. The main subjects addressed are the rapid changes in the sizes of old galaxies, the

  18. Galaxy evolution in clusters since z=1

    Science.gov (United States)

    Aragón-Salamanca, A.

    2011-11-01

    It is now 30 years since Alan Dressler published his seminal paper onthe morphology-density relation. Although there is still much to learnon the effect of the environment on galaxy evolution, extensive progress has been made since then both observationally and theoretically.Galaxy clusters provide some of the most extreme environments in which galaxies evolve, making them excellent laboratories to study the age old question of "nature'' vs. "nurture'' in galaxy evolution. Here I review some of the key observational results obtained during the last decade on the evolution of the morphology, structure, dynamics, star-formation history and stellar populations of cluster galaxies since the time when the universe was half its present age.Many of the results presented here have been obtainedwithin the ESO Distant Cluster Survey (EDisCS) and Space Telescope A901/02 Galaxy Evolution Survey (STAGES) collaborations.

  19. Constraining SNe Enrichment Using X-ray Observations of Clusters of Galaxies

    Science.gov (United States)

    Bulbul, G. Esra; Smith, R.; Lowenstein, M.

    2012-05-01

    X-ray spectroscopy yields accurate measurements of metal enrichment in the intra-cluster medium (ICM). The large reservoir of metals in clusters of galaxies provides a unique way to probe the total number and fraction of supernovae (SNe) types that enrich the ICM integrated over the cluster life-time by directly modeling high spectral resolution X-ray observations using various nucleosynthesis models. The XSPEC model, snapec, offering the possibility to use these vast reservoir of metals in clusters of galaxies to probe the supernovae rates and thereby test the SNe type Ia progenitor models. We will present the evolution of SNe type Ia rate obtained from the XMM-Newton observations of clusters of galaxies to constrain the possible SNe type Ia progenitors.

  20. The influence of halo evolution on galaxy structure

    Science.gov (United States)

    White, Simon

    2015-03-01

    If Einstein-Newton gravity holds on galactic and larger scales, then current observations demonstrate that the stars and interstellar gas of a typical bright galaxy account for only a few percent of its total nonlinear mass. Dark matter makes up the rest and cannot be faint stars or any other baryonic form because it was already present and decoupled from the radiation plasma at z = 1000, long before any nonlinear object formed. The weak gravito-sonic waves so precisely measured by CMB observations are detected again at z = 4 as order unity fluctuations in intergalactic matter. These subsequently collapse to form today's galaxy/halo systems, whose mean mass profiles can be accurately determined through gravitational lensing. High-resolution simulations link the observed dark matter structures seen at all these epochs, demonstrating that they are consistent and providing detailed predictions for all aspects of halo structure and growth. Requiring consistency with the abundance and clustering of real galaxies strongly constrains the galaxy-halo relation, both today and at high redshift. This results in detailed predictions for galaxy assembly histories and for the gravitational arena in which galaxies live. Dark halos are not expected to be passive or symmetric but to have a rich and continually evolving structure which will drive evolution in the central galaxy over its full life, exciting warps, spiral patterns and tidal arms, thickening disks, producing rings, bars and bulges. Their growth is closely related to the provision of new gas for galaxy building.

  1. Galaxy Zoo: Observing secular evolution through bars

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Edmond; Faber, S. M.; Koo, David C. [Department of Astronomy and Astrophysics, 1156 High Street, University of California, Santa Cruz, CA 95064 (United States); Athanassoula, E.; Bosma, A. [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Masters, Karen L.; Nichol, Robert C.; Melvin, Thomas [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Lintott, Chris [Oxford Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Schawinski, Kevin [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Skibba, Ramin A. [Center for Astrophysics and Space Sciences, Department of Physics, 9500 Gilman Drive, University of California, San Diego, CA 92093 (United States); Willett, Kyle W., E-mail: ec2250@gmail.com [School of Physics and Astronomy, University of Minnesota, MN 55455 (United States)

    2013-12-20

    In this paper, we use the Galaxy Zoo 2 data set to study the behavior of bars in disk galaxies as a function of specific star formation rate (SSFR) and bulge prominence. Our sample consists of 13,295 disk galaxies, with an overall (strong) bar fraction of 23.6% ± 0.4%, of which 1154 barred galaxies also have bar length (BL) measurements. These samples are the largest ever used to study the role of bars in galaxy evolution. We find that the likelihood of a galaxy hosting a bar is anticorrelated with SSFR, regardless of stellar mass or bulge prominence. We find that the trends of bar likelihood and BL with bulge prominence are bimodal with SSFR. We interpret these observations using state-of-the-art simulations of bar evolution that include live halos and the effects of gas and star formation. We suggest our observed trends of bar likelihood with SSFR are driven by the gas fraction of the disks, a factor demonstrated to significantly retard both bar formation and evolution in models. We interpret the bimodal relationship between bulge prominence and bar properties as being due to the complicated effects of classical bulges and central mass concentrations on bar evolution and also to the growth of disky pseudobulges by bar evolution. These results represent empirical evidence for secular evolution driven by bars in disk galaxies. This work suggests that bars are not stagnant structures within disk galaxies but are a critical evolutionary driver of their host galaxies in the local universe (z < 1).

  2. Galaxy luminosity function: evolution at high redshift

    Science.gov (United States)

    Martinet, N.; Durret, F.; Guennou, L.; Adami, C.

    2014-12-01

    There are some disagreements about the abundance of faint galaxies in high redshift clusters. DAFT/FADA (Dark energy American French Team) is a medium redshift (0.4galaxy clusters ideal to tackle these problems. We present cluster galaxy luminosity functions (GLFs) based on photometric redshifts for 30 clusters in B, V, R and I restframe bands. We show that completeness is a key parameter to understand the different observed behaviors when fitting the GLFs. We also investigate the evolution of GLFs with redshift for red and blue galaxy populations separately. We find a drop of the faint end of red GLFs which is more important at higher redshift while the blue GLF faint end remains flat in our redshift range. These results can be interpreted in terms of galaxy quenching. Faint blue galaxies transform into red ones which enrich the red sequence from high to low redshifts in clusters while some blue galaxies are still accreted from the environment, compensating for this evolution so that the global GLF does not seem to evolve.

  3. The orbital evolution of binary galaxies

    Science.gov (United States)

    Chan, R.; Junqueira, S.

    2001-02-01

    We present the results of self-consistent numerical simulations performed to study the orbital circularization of binary galaxies. We have generalized a previous model (Junqueira & de Freitas Pacheco 1994) and confirmed partially their results. The orbital evolution of pairs of galaxies is faster when we consider interacting pairs with contacting ``live'' galaxy halos but the circularization time remains larger than the Hubble time. Besides, the time behavior of the orbits has changed in comparison with previous work because of tidal forces and dynamical friction acting on the halos.

  4. Evolution of Galaxies in the Cosmic Web

    Science.gov (United States)

    Darvish Sarvestani, Behnam

    2015-12-01

    We study the effects of environment on the evolution of galaxies, with an emphasis on two different approaches towards the definition of environment: (1) environment defined based on the local surface density of galaxies and (2) environment defined based on the major components of the cosmic web; i.e., filaments, clusters and the field. In the first approach, surface density field is estimated using a variety of estimators and tested with simulations. Using the estimated surface densities assigned to galaxies, we observe a strong environmental dependence on the properties of galaxies (e.g., SFR, sSFR and the quiescent fraction) at z ≤ 1. We explore the fractional role of stellar mass and environment in quenching the star-formation. In the second approach, we use the Multi-scale Morphology Filter algorithm to disentangle the density field into its component. We apply this method to a sample of star-forming galaxies for a large-scale structure at z ˜0.84 in the HiZELS-COSMOS field. We show that the observed median SFR, stellar mass, sSFR, the mean SFR-mass relation and its scatter for star-forming galaxies do not strongly depend on the cosmic web. However, the fraction of Halpha star-forming galaxies varies with environment and is enhanced in filaments. Furthermore, we study the physical properties of a spectroscopic sample of star-forming galaxies in a large filament in the COSMOS field at z ˜0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of field galaxies. We spectroscopically confirm the presence of a large galaxy filament (˜ 8 Mpc). We show that within the uncertainties, the ionization parameter, EW, EW versus sSFR relation, EW versus stellar mass relation, line-of-sight velocity dispersion, dynamical mass, and stellar-to-dynamical mass ratio are similar for filament and field star-forming galaxies. However, we show that on average, filament star-forming galaxies are more metal-enriched (˜ 0

  5. Outskirts of spiral galaxies: result of a secular evolution process?.

    Science.gov (United States)

    Bakos, J.; Trujillo, I.; Azzollini, R.; Beckman, J. E.; Pohlen, M.

    We present our recent results on the properties of the outskirts of disk galaxies. In particular, we focus on spiral galaxies with stellar disk truncations in their radial surface brightness profiles. Using SDSS, UDF and GOODS data we show how the position of the break (i.e., a direct estimator of the size of the stellar disk) evolves with time since z˜1. Our findings agree with an evolution on the radial position of the break by a factor of 1.3±0.1 in the last 8 Gyr for galaxies with similar stellar masses. We also present radial color gradients and how they evolve with time. At all redshift we find a radial inside-out bluing reaching a minimum at the position of the break radius, this minimum is followed by a reddening outwards. Our results constrain several galaxy disk formation models and favour a scenario where stars are formed inside the break radius and are relocated in the outskirts of galaxies through secular processes.

  6. Monolithic View of Galaxy Formation and Evolution

    Directory of Open Access Journals (Sweden)

    Cesare Chiosi

    2014-07-01

    Full Text Available We review and critically discuss the current understanding of galaxy formation and evolution limited to Early Type Galaxies (ETGs as inferred from the observational data and briefly contrast the hierarchical and quasi-monolithic paradigms of formation and evolution. Since in Cold Dark Matter (CDM cosmogony small scale structures typically collapse early and form low-mass haloes that subsequently can merge to assembly larger haloes, galaxies formed in the gravitational potential well of a halo are also expected to merge thus assembling their mass hierarchically. Mergers should occur all over the Hubble time and large mass galaxies should be in place only recently. However, recent observations of high redshift galaxies tell a different story: massive ETGs are already in place at high redshift. To this aim, we propose here a revision of the quasi-monolithic scenario as an alternative to the hierarchical one, in which mass assembling should occur in early stages of a galaxy lifetime and present recent models of ETGs made of Dark and Baryonic Matter in a Λ-CDM Universe that obey the latter scheme. The galaxies are followed from the detachment from the linear regime and Hubble flow at z ≥ 20 down to the stage of nearly complete assembly of the stellar content (z ∼ 2 − 1 and beyond.  It is found that the total mass (Mh = MDM + MBM and/or initial over-density of the proto-galaxy drive the subsequent star formation histories (SFH. Massive galaxies (Mh ~ _1012M⊙ experience a single, intense burst of star formation (with rates ≥ 103M⊙/yr at early epochs, consistently with observations, with a weak dependence on the initial over-density; intermediate mass haloes (Mh~_ 1010 − 1011M⊙ have star formation histories that strongly depend on their initial over-density; finally, low mass haloes (Mh ~_ 109M⊙ always have erratic, burst-like star forming histories. The present-day properties (morphology, structure, chemistry and photometry of the

  7. Multiwavelength Mapping of Galaxy Formation and Evolution

    CERN Document Server

    Renzini, Alvio; ESO Workshop

    2005-01-01

    The possibilities of astronomical observation have dramatically increased over the last decade. Major satellites, like the Hubble Space Telescope, Chandra and XMM Newton, are complemented by numerous large ground-based observatories, from 8m-10m optical telescopes to sub-mm and radio facilities. As a result, observational astronomy has access to virtually the whole electromagnetic spectrum of galaxies, even at high redshifts. Theoretical models of galaxy formation and cosmological evolution now face a serious challenge to match the plethora of observational data. In October 2003, over 170 astronomers from 15 countries met for a 4-day workshop to extensively illustrate and discuss all major observational projects and ongoing theoretical efforts to model galaxy formation and evolution. This volume contains the complete proceedings of this meeting and is therefore a unique and timely overview of the current state of research in this rapidly evolving field.

  8. Circumgalactic Matter Matters in Galaxy Evolution

    Science.gov (United States)

    Werk, Jessica

    2018-01-01

    The circumgalactic medium (CGM; non-ISM gas within a galaxy virial radius) regulates the gas flows that shape the assembly and evolution of galaxies. Owing to the vastly improved capabilities in space-based UV spectroscopy with the installation of HST/COS, observations and simulations of the CGM have emerged as the new frontier of galaxy evolution studies. In the last decade, we have learned that the CGM of Milky Way mass galaxies likely contains enough material to harbor most of the metals lost in galaxy winds and to sustain star-formation for billions of years. Remarkably, this implies that most of the heavy elements on earth cycled back and forth multiple times through the Milky Way’s own CGM before the formation of the solar system. In this talk, I will describe constraints we have placed on the origin and fate of this material by studying the gas kinematics, metallicity and ionization state. I will conclude by posing several unanswered questions about the CGM that will be addressed with future survey data and hydrodynamic simulations in a cosmological context.

  9. What Drives the Kinematic Evolution of Galaxies?

    Science.gov (United States)

    Hung, Chao-Ling

    2017-07-01

    One important result from recent large integral field spectrograph (IFS) surveys is that the intrinsic velocity dispersion of galaxies increases at high redshift. While massive, rotation-dominated disks are already in place at z 2, they are dynamically hotter compared to spiral galaxies in the local Universe. Although several plausible mechanisms have been proposed (e.g., star formation feedback, elevated gas supply, or galaxy interaction), it remains unclear what is the fundamental driver of the velocity dispersion enhancement at high-z. We investigate the origin of this kinematic evolution using a suite of cosmological simulations from the FIRE (Feedback In Realistic Environments) project. Although the velocity dispersion of simulated galaxies is systematically lower compared to the observed values, the simulations successfully reproduce the observed trends between velocity dispersion, SFR, and redshift. In the FIRE simulations, the variation in velocity dispersion is highly dynamic across cosmic time, and it can vary significantly within a timescale of 100 Myr. These variations closely mirror the evolution of star formation and gas inflow histories. By cross-correlating any two parameters of velocity dispersion, gas inflow rates, and SFR, we show that the increase of gas inflowing into the galaxy lead to the subsequent star formation activities, and the enhancement of velocity dispersion follows closely in time with the increasing gas inflow rates and SFR.

  10. Angular momentum evolution of galaxies in EAGLE

    Science.gov (United States)

    Lagos, Claudia del P.; Theuns, Tom; Stevens, Adam R. H.; Cortese, Luca; Padilla, Nelson D.; Davis, Timothy A.; Contreras, Sergio; Croton, Darren

    2017-02-01

    We use the EAGLE cosmological hydrodynamic simulation suite to study the specific angular momentum of galaxies, j, with the aims of (i) investigating the physical causes behind the wide range of j at fixed mass and (ii) examining whether simple, theoretical models can explain the seemingly complex and non-linear nature of the evolution of j. We find that j of the stars, jstars, and baryons, jbar, are strongly correlated with stellar and baryon mass, respectively, with the scatter being highly correlated with morphological proxies such as gas fraction, stellar concentration, (u-r) intrinsic colour, stellar age and the ratio of circular velocity to velocity dispersion. We compare with available observations at z = 0 and find excellent agreement. We find that jbar follows the theoretical expectation of an isothermal collapsing halo under conservation of specific angular momentum to within ≈50 per cent, while the subsample of rotation-supported galaxies are equally well described by a simple model in which the disc angular momentum is just enough to maintain marginally stable discs. We extracted evolutionary tracks of the stellar spin parameter of EAGLE galaxies and found that the fate of their jstars at z = 0 depends sensitively on their star formation and merger histories. From these tracks, we identified two distinct physical channels behind low jstars galaxies at z = 0: (i) galaxy mergers, and (ii) early star formation quenching. The latter can produce galaxies with low jstars and early-type morphologies even in the absence of mergers.

  11. Galaxy Evolution Spectroscopic Explorer: Scientific Rationale

    Science.gov (United States)

    Heap, Sara; Ninkov, Zoran; Robberto, Massimo; Hull, Tony; Purves, Lloyd

    2016-01-01

    GESE is a mission concept consisting of a 1.5-m space telescope and UV multi-object slit spectrograph designed to help understand galaxy evolution in a critical era in the history of the universe, where the rate of star-formation stopped increasing and started to decline. To isolate and identify the various processes driving the evolution of these galaxies, GESE will obtain rest-frame far-UV spectra of 100,000 galaxies at redshifts, z approximately 1-2. To obtain such a large number of spectra, multiplexing over a wide field is an absolute necessity. A slit device such as a digital micro-mirror device (DMD) or a micro-shutter array (MSA) enables spectroscopy of a hundred or more sources in a single exposure while eliminating overlapping spectra of other sources and blocking unwanted background like zodiacal light. We find that a 1.5-m space telescope with a MSA slit device combined with a custom orbit enabling long, uninterrupted exposures (approximately 10 hr) are optimal for this spectroscopic survey. GESE will not be operating alone in this endeavor. Together with x-ray telescopes and optical/near-IR telescopes like Subaru/Prime Focus Spectrograph, GESE will detect "feedback" from young massive stars and massive black holes (AGN's), and other drivers of galaxy evolution.

  12. The AMBRE Project: Constraining the lithium evolution in the Milky Way

    OpenAIRE

    Guiglion, G.; de Laverny, P.; Recio-Blanco, A.; Worley, C. C.; De Pascale, M.; Masseron, T.; Prantzos, N.; Mikolaitis, S.

    2016-01-01

    The chemical evolution of lithium in the Milky Way represents a major problem in modern astrophysics. Indeed, lithium is, on the one hand, easily destroyed in stellar interiors, and, on the other hand, produced at some specific stellar evolutionary stages that are still not well constrained. The goal of this paper is to investigate the lithium stellar content of Milky Way stars in order to put constraints on the lithium chemical enrichment in our Galaxy, in particular in both the thin and thi...

  13. Evolution of dwarf galaxies in the Centaurus A group

    OpenAIRE

    Makarova, L.; Makarov, D.

    2007-01-01

    We consider star formation properties of dwarf galaxies in Cen A group observed within our HST/ACS projects number 9771 and 10235. We model color-magnitude diagrams of the galaxies under consideration and measure star formation rate and metallicity dependence on time. We study environmental dependence of the galaxy evolution and probable origin of the dwarf galaxies in the group.

  14. Evolution of Compact Extreme Starburst Galaxies

    Science.gov (United States)

    Lowenthal, James; Bershady, Matthew; Gallego, Jesus; Guzman, Rafael; Hameed, Salman; Koo, David

    2006-05-01

    The global SFR was tenfold greater at z=1 than at z=0, and "downsizing" scenarios of galaxy formation maintain that the strong evolution in SFR progresses from high- to low-mass systems with time. Meanwhile, large reservoirs of star formation previously hidden from the optical by obscuring dust are being uncovered in the IR and submm in diverse populations of galaxies over a wide range of redshift. We propose deep IRAC imaging and MIPS photometry of a unique sample of well-studied 26 extreme starburst galaxies, half of them nearby HII galaxies and the other half luminous compact blue galaxies (LCBGs) at redshift z~0.5. These intensely starforming but mostly low-mass systems, like their massive cousins the ultraluminous infrared galaxies (ULIRGs), apparently evolve significantly: they can account for as much as 40% of the increase in global SFR observed between z=0 and z=1. They may also include local analogs of Lyman break galaxies at z~3, and are probably the same class of UV-bright starbursts recently observed in the local universe with GALEX. Coverage of our sample has two significant advantages over other multiwavelength surveys: spatially resolved HST/STIS-UV and optical imaging and spectroscopy, and high spectral and spatial resolution 2D spectroscopy with Keck/HIRES. Thus we can measure important physical parameters that are unavailable with the FLS, EGSS, GOODS, and other surveys. Our main science goal is (1) to use the mid- and far-IR emission to measure optically obscured star formation from z~1 to z=0 as a function of dynamical mass and rest-UV size and morphology; this will directly address inconsistencies in our current downsizing picture of galaxy evolution and the role of compact extreme starbursts. We also plan (2) to compare the SEDs of our samples to those of LBGs, to test the hypothesis that LCBGs include local analogs of LBGs; and (3) to measure the starbursts' stellar masses in the rest-NIR, which is necessary for analysis of SFH, b parameter

  15. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Pryds, Nini

    A mesoscale numerical model able to simulate solid state constrained sintering is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element method for calculating stresses. The sintering behavior of a sample constrained by a rigid substrate...

  16. Chemical Evolution Library for Galaxy Formation Simulation

    Science.gov (United States)

    Saitoh, Takayuki R.

    2017-02-01

    We have developed a software library for chemical evolution simulations of galaxy formation under the simple stellar population (SSP) approximation. In this library, all of the necessary components concerning chemical evolution, such as initial mass functions, stellar lifetimes, yields from Type II and Type Ia supernovae, asymptotic giant branch stars, and neutron star mergers, are compiled from the literature. Various models are pre-implemented in this library so that users can choose their favorite combination of models. Subroutines of this library return released energy and masses of individual elements depending on a given event type. Since the redistribution manner of these quantities depends on the implementation of users’ simulation codes, this library leaves it up to the simulation code. As demonstrations, we carry out both one-zone, closed-box simulations and 3D simulations of a collapsing gas and dark matter system using this library. In these simulations, we can easily compare the impact of individual models on the chemical evolution of galaxies, just by changing the control flags and parameters of the library. Since this library only deals with the part of chemical evolution under the SSP approximation, any simulation codes that use the SSP approximation—namely, particle-base and mesh codes, as well as semianalytical models—can use it. This library is named “CELib” after the term “Chemical Evolution Library” and is made available to the community.

  17. Bulge-Disk Evolution in Interacting Bulgeless Galaxies

    Science.gov (United States)

    Das, M.; Ramya, S.; Sengupta, C.; Mishra, K.

    2013-10-01

    Bulgeless galaxies are an extreme class of late type spiral galaxies that have practically no bulge and are nearly pure disk in morphology. Their lack of evolution is a puzzle for theories of galaxy formation and the secular evolution of galaxy disks. However, one of the processes by which these galaxies could evolve is through interactions with other galaxies. In this study we present radio (GMRT) observations of star formation in a sample of bulgeless galaxies. We did followup Hα imaging and optical spectroscopy of two galaxies, NGC 3445 and NGC 4027. Both galaxies have extended emission associated with their tidal interactions. Their nuclei show ongoing star formation but no signs of AGN activity. The R band images suggest that their centers have oval distortions or pseudobulges that may later evolve into larger bulges. Thus interactions are an important trigger for the formation of bulges in such disk dominated systems.

  18. Significance of Environmental Density in Shocked Poststarburst Galaxy Evolution

    Science.gov (United States)

    Jaliff, Laura

    2018-01-01

    The Shocked POstarbusrt Galaxy Survey (SPOGS) comprises 1,066 galaxies undergoing the transformation from blue cloud late-type spirals to red sequence non-star-forming early-type ellipticals and lenticulars. They are selected via spectral analysis of ionized gas line ratios, which indicate shocked objects, and Balmer H-δ equivalent width, which select recently formed stars, but not active star formation. E+A galaxies (Zabludoff et al. 1996), like SPOGs, contain young stars but, unlike SPOGs, no emission lines consistent with star formation. They differ in that the quality used to discern SPOGs, their shocks, produces H-α lines that prevent them from being found via the same criteria as E+As. Thus, SPOGs can be found before being entirely stripped of their gas, and, while E+As are largely red and dead, found leaving the green valley, SPOGS are mostly entering it. The environmental density data for SPOGs was retrieved via the NASA Extragalactic Database (NED) radial velocity constrained cone tool, which provides counts and densities within spheres of radii 1, 5, and 10 Mpc from the center of search as well as relative positions and redshifts of objects. The kinematic morphology-density relation (Cappellari et al. 2011) is employed as a point of comparison for how SPOGs’ environmental densities might relate to morphological and spectroscopic factors, including tidal features, asymmetry, and color, in order to fully understand the role of environmental factors in SPOGS object evolution.

  19. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Pryds, Nini

    2014-01-01

    A numerical model able to simulate solid state constrained sintering is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element model (FEM) for calculating stresses on a microstructural level. The microstructural response to the local stress...

  20. Modeling the Microstructural Evolution During Constrained Sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Pryds, Nini

    2015-01-01

    A numerical model able to simulate solid-state constrained sintering is presented. The model couples an existing kinetic Monte Carlo model for free sintering with a finite element model (FEM) for calculating stresses on a microstructural level. The microstructural response to the local stress...

  1. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Tikare, V.

    A numerical model able to simulate solid state constrained sintering of a powder compact is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element (FE) method for calculating stresses on a microstructural level. The microstructural response...

  2. The Evolution of Galaxies in Cluster Environment; HI Perspective

    NARCIS (Netherlands)

    Fujita, A.; van Gorkom, J.; van Kampen, E.

    1999-01-01

    We investigate the degree to which the environment affects the evolution of galaxies in clusters. One way is to study the fate of gas in cluster galaxies by deep HI synthesis imaging. We are interested in the correlation between HI deficiency of galaxies and the dynamical states of clusters/the

  3. The new galaxy evolution paradigm revealed by the Herschel surveys

    Science.gov (United States)

    Eales, Stephen; Smith, Dan; Bourne, Nathan; Loveday, Jon; Rowlands, Kate; van der Werf, Paul; Driver, Simon; Dunne, Loretta; Dye, Simon; Furlanetto, Cristina; Ivison, R. J.; Maddox, Steve; Robotham, Aaron; Smith, Matthew W. L.; Taylor, Edward N.; Valiante, Elisabetta; Wright, Angus; Cigan, Philip; De Zotti, Gianfranco; Jarvis, Matt J.; Marchetti, Lucia; Michałowski, Michał J.; Phillipps, Steven; Viaene, Sebastien; Vlahakis, Catherine

    2018-01-01

    The Herschel Space Observatory has revealed a very different galaxyscape from that shown by optical surveys which presents a challenge for galaxy-evolution models. The Herschel surveys reveal (1) that there was rapid galaxy evolution in the very recent past and (2) that galaxies lie on a single Galaxy Sequence (GS) rather than a star-forming 'main sequence' and a separate region of 'passive' or 'red-and-dead' galaxies. The form of the GS is now clearer because far-infrared surveys such as the Herschel ATLAS pick up a population of optically red star-forming galaxies that would have been classified as passive using most optical criteria. The space-density of this population is at least as high as the traditional star-forming population. By stacking spectra of H-ATLAS galaxies over the redshift range 0.001 < z < 0.4, we show that the galaxies responsible for the rapid low-redshift evolution have high stellar masses, high star-formation rates but, even several billion years in the past, old stellar populations - they are thus likely to be relatively recent ancestors of early-type galaxies in the Universe today. The form of the GS is inconsistent with rapid quenching models and neither the analytic bathtub model nor the hydrodynamical EAGLE simulation can reproduce the rapid cosmic evolution. We propose a new gentler model of galaxy evolution that can explain the new Herschel results and other key properties of the galaxy population.

  4. Galaxy Evolution Insights from Spectral Modeling of Large Data Sets from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Hoversten, Erik A. [Johns Hopkins Univ., Baltimore, MD (United States)

    2007-10-01

    This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisiting the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set (~ 105 galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy Hα equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M is Γ = 1.5 ± 0.1 with the error dominated by systematics. Galaxies brighter than around Mr,0.1 = -20 (including galaxies like the Milky Way which has Mr,0.1 ~ -21) are well fit by a universal Γ ~ 1.4 IMF, similar to the classical Salpeter slope, and smooth, exponential star formation histories (SFH). Fainter galaxies prefer steeper IMFs and the quality of the fits reveal that for these galaxies a universal IMF with smooth SFHs is actually a poor assumption. Related projects are also pursued. A targeted photometric search is conducted for strongly lensed Lyman break galaxies (LBG) similar to MS1512-cB58. The evolution of the photometric selection technique is described as are the results of spectroscopic follow-up of the best targets. The serendipitous discovery of two interesting blue compact dwarf galaxies is reported. These

  5. Environmental Effects On Galaxy Evolution In Semi-analytic Models

    Science.gov (United States)

    Lee, Jaehyun; Jung, I.; Yi, S.

    2012-01-01

    We have investigated the evolution of galaxy morphology and its mixture in various halo environments by taking advantages of N-body simulations and semi-analytic approach. Dark matter halos have different growth histories depending on the long-range density (voids vs clusters). Since dynamical properties of dark matter halos decide their merger timescales and galaxy properties residing in the halos, different dark matter halo assemblies make different galaxy merger histories. Thus, it is expected that galaxies in voids and clusters may show different evolutionary histories and morphology mixtures because galaxy mergers play a pivotal role in the galaxy morphology transformation. To examine it, dark matter halo merger trees in various density regions are extracted from N-body simulations, and the evolutionary histories of galaxies are computed with our semi-analytic model code based on the N-body backbones. We present the difference of evolutionary histories and morphology mixtures of galaxies that reside in voids and dense regions.

  6. THE COSMIC EVOLUTION OF FAINT SATELLITE GALAXIES AS A TEST OF GALAXY FORMATION AND THE NATURE OF DARK MATTER

    Energy Technology Data Exchange (ETDEWEB)

    Nierenberg, A. M.; Treu, T. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Menci, N. [NAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy); Lu, Y. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA 94309 (United States); Wang, W., E-mail: amn01@physics.ucsb.edu [Key Laboratory for Research in Galaxies and Cosmology of Chinese Academy of Sciences, Max-Planck-Institute Partner Group, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China)

    2013-08-01

    The standard cosmological model based on cold dark matter (CDM) predicts a large number of subhalos for each galaxy-size halo. Matching the subhalos to the observed properties of luminous satellites of galaxies in the local universe poses a significant challenge to our understanding of the astrophysics of galaxy formation. We show that the cosmic evolution and host mass dependence of the luminosity function of satellites provide a powerful new diagnostic to disentangle astrophysical effects from variations in the underlying dark matter mass function. We illustrate this by comparing recent observations of satellites between redshifts 0.1 < z < 0.8 based on Hubble Space Telescope images, with predictions from three different state-of-the-art semi-analytic models applied to CDM power spectra, with one model also applied to a warm dark matter (WDM) spectrum. We find that even though CDM models provide a reasonable fit to the local luminosity function of satellites around galaxies comparable to the Milky Way, they do not reproduce the data as well for different redshifts and host galaxy stellar masses, indicating that further improvements in the description of star formation are likely needed. The WDM model matches the observed mass dependence and redshift evolution of satellite galaxies more closely, indicating that a modification of the underlying power spectrum may offer an alternative solution to this tension. We conclude by presenting predictions for the color distribution of satellite galaxies to demonstrate how future observations will be able to further distinguish between these models and to help constrain baryonic and non-baryonic physics.

  7. Automata network models of galaxy evolution

    Science.gov (United States)

    Chappell, David; Scalo, John

    1993-01-01

    Two ideas appear frequently in theories of star formation and galaxy evolution: (1) star formation is nonlocally excitatory, stimulating star formation in neighboring regions by propagation of a dense fragmenting shell or the compression of preexisting clouds; and (2) star formation is nonlocally inhibitory, making H2 regions and explosions which can create low-density and/or high temperature regions and increase the macroscopic velocity dispersion of the cloudy gas. Since it is not possible, given the present state of hydrodynamic modeling, to estimate whether one of these effects greatly dominates the other, it is of interest to investigate the predicted spatial pattern of star formation and its temporal behavior in simple models which incorporate both effects in a controlled manner. The present work presents preliminary results of such a study which is based on lattice galaxy models with various types of nonlocal inhibitory and excitatory couplings of the local SFR to the gas density, temperature, and velocity field meant to model a number of theoretical suggestions.

  8. Constraining the Stellar Populations and Star Formation Histories of Blue Compact Dwarf Galaxies with SED Fits

    Energy Technology Data Exchange (ETDEWEB)

    Janowiecki, Steven [International Center for Radio Astronomy Research, M468, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 (Australia); Salzer, John J.; Zee, Liese van [Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405 (United States); Rosenberg, Jessica L. [Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030 (United States); Skillman, Evan, E-mail: steven.janowiecki@uwa.edu.au [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street, SE Minneapolis, MN, 55455 (United States)

    2017-02-10

    We discuss and test possible evolutionary connections between blue compact dwarf galaxies (BCDs) and other types of dwarf galaxies. BCDs provide ideal laboratories to study intense star formation episodes in low-mass dwarf galaxies, and have sometimes been considered a short-lived evolutionary stage between types of dwarf galaxies. To test these connections, we consider a sample of BCDs as well as a comparison sample of nearby galaxies from the Local Volume Legacy (LVL) survey for context. We fit the multi-wavelength spectral energy distributions (SED, far-ultra-violet to far-infrared) of each galaxy with a grid of theoretical models to determine their stellar masses and star formation properties. We compare our results for BCDs with the LVL galaxies to put BCDs in the context of normal galaxy evolution. The SED fits demonstrate that the star formation events currently underway in BCDs are at the extreme of the continuum of normal dwarf galaxies, both in terms of the relative mass involved and in the relative increase over previous star formation rates. Today’s BCDs are distinctive objects in a state of extreme star formation that is rapidly transforming them. This study also suggests ways to identify former BCDs whose star formation episodes have since faded.

  9. Recent Structural Evolution of Early-Type Galaxies: Size Growth from z = 1 to z = 0

    Science.gov (United States)

    van der Wel, Arjen; Holden, Bradford P.; Zirm, Andrew W.; Franx, Marijn; Rettura, Alessandro; Illingworth, Garth D.; Ford, Holland C.

    2008-11-01

    Strong size and internal density evolution of early-type galaxies between z ~ 2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z ~ 1) galaxies with dynamically measured masses in order to confirm the previous, model-dependent results and constrain the uncertainties that may play a role. Velocity dispersion (σ) measurements are taken from the literature for 50 morphologically selected 0.8 University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  10. Reading the Chemical Evolution of Stellar Populations in Dwarf Galaxies

    OpenAIRE

    Hendricks, Benjamin Thomas

    2015-01-01

    In this thesis I present observations and analyses addressed to understand the individual evolution of dwarf galaxies and the interdependency with their local environment. My study focuses on the Fornax dwarf spheroidal galaxy, which is the most massive galaxy of its type in the Local Group, hosting stars with a broad range in age and metallicity. Additionally, it is the only intact dwarf spheroidal with an own globular cluster system. Therefore, it provides a superb laboratory to...

  11. Constraining Gravity at Large Scales with Clusters of Galaxies

    Science.gov (United States)

    Rapetti, D.; Cataneo, M.; Schmidt, F.; Lombriser, L.; Li, B.; Mantz, A.; Allen, S.; Applegate, D.; Kelly, P.; von der Linden, A.; Morris, R. G.

    2017-01-01

    I will present the most recent constraints on f(R) modifications of gravity from the abundance of massive galaxy clusters. Our analysis self-consistently and simultaneously incorporates survey, observable-mass scaling relations, as well as weak gravitational lensing data to accurately calibrate the absolute cluster mass scale. Using this advanced cluster analysis in combination with CMB data, and other cosmological constraints, we obtain upper bounds on f(R) gravity that are about an order of magnitude tighter than those from such previous studies. The robustness of our results derives from our high quality cluster growth data out to redshifts z 0 . 5 , a tight control of systematic uncertainties, accounting for the covariance between all parameters, and the use of the full shape of the halo mass function (HMF) over the mass range of the data. Based on the current highest resolution N-body simulations, I will also describe our new modeling of the f(R) HMF. This includes novel corrections to capture key non-linear effects of the Chameleon screening mechanism that will allow us to obtain the next generation of cluster constraints on this model. DR is supported by an NPP Senior Fellowship at NASA ARC, administered by USRA under contract with NASA.

  12. Gas mass fractions and the evolution of spiral galaxies

    NARCIS (Netherlands)

    McGaugh, SS; DeBlok, WJG

    1997-01-01

    We show that the gas mass fraction of spiral galaxies is strongly correlated with luminosity and surface brightness. It is not correlated with linear size. Gas fraction varies with luminosity and surface brightness at the same rate, indicating evolution at fixed size. Dim galaxies are clearly less

  13. Evolution of the atomic and molecular gas content of galaxies

    NARCIS (Netherlands)

    Popping, Gergö; Somerville, Rachel S.; Trager, Scott C.

    We study the evolution of atomic and molecular gas in galaxies in semi-analytic models of galaxy formation that include new modelling of the partitioning of cold gas in galactic discs into atomic, molecular, and ionized phases. We adopt two scenarios for the formation of molecules: one pressure

  14. Predicting galaxy star formation rates via the co-evolution of galaxies and haloes

    Science.gov (United States)

    Watson, Douglas F.; Hearin, Andrew P.; Berlind, Andreas A.; Becker, Matthew R.; Behroozi, Peter S.; Skibba, Ramin A.; Reyes, Reinabelle; Zentner, Andrew R.; van den Bosch, Frank C.

    2015-01-01

    In this paper, we test the age matching hypothesis that the star formation rate (SFR) of a galaxy of fixed stellar mass is determined by its dark matter halo formation history, e.g. more quiescent galaxies reside in older haloes. We present new Sloan Digital Sky Survey measurements of the galaxy two-point correlation function and galaxy-galaxy lensing as a function of stellar mass and SFR, separated into quenched and star-forming galaxy samples to test this simple model. We find that our age matching model is in excellent agreement with these new measurements. We also find that our model is able to predict: (1) the relative SFRs of central and satellite galaxies, (2) the SFR dependence of the radial distribution of satellite galaxy populations within galaxy groups, rich groups, and clusters and their surrounding larger scale environments, and (3) the interesting feature that the satellite quenched fraction as a function of projected radial distance from the central galaxy exhibits an ˜r-.15 slope, independent of environment. These accurate predictions are intriguing given that we do not explicitly model satellite-specific processes after infall, and that in our model the virial radius does not mark a special transition region in the evolution of a satellite. The success of the model suggests that present-day galaxy SFR is strongly correlated with halo mass assembly history.

  15. Mild evolution of the stellar metallicity gradients of disc galaxies

    Science.gov (United States)

    Tissera, Patricia B.; Machado, Rubens E. G.; Vilchez, José M.; Pedrosa, Susana E.; Sanchez-Blazquez, Patricia; Varela, Silvio

    2017-08-01

    Context. The metallicity gradients of the stellar populations in disc galaxies and their evolution store relevant information on the disc formation history and on those processes which could mix stars a posteriori, such as migration, bars and/or galaxy-galaxy interactions. Aims: We aim to investigate the evolution of the metallicity gradients of the whole stellar populations in disc components of simulated galaxies in a cosmological context. Methods: We analyse simulated disc galaxies selected from a cosmological hydrodynamical simulation that includes chemical evolution and a physically motivated supernova feedback capable of driving mass-loaded galactic winds. Results: We detect a mild evolution with redshift in the metallicity slopes of - 0.02 ± 0.01 dex kpc-1 from z 1. If the metallicity profiles are normalised by the effective radius of the stellar disc, the slopes show no clear evolution for zmigration albeit weaker than in previous works. Conclusions: Our stellar discs show a mild evolution of the stellar metallicity slopes up to z 1, which is well-matched by the evolution calculated archeologically from the abundance distributions of mono-age stellar populations at z 0. The dispersion in the relations allows for stronger individual evolutions. Overall, supernova feedback could explain the trends but an impact of migration can not be totally discarded. Galaxy-galaxy interactions or small satellite accretions can also contribute to modify the metallicity profiles in the outer parts. Disentangling the effects of these processes for individual galaxies is still a challenge in a cosmological context.

  16. Improved Differential Evolution with Shrinking Space Technique for Constrained Optimization

    Science.gov (United States)

    Fu, Chunming; Xu, Yadong; Jiang, Chao; Han, Xu; Huang, Zhiliang

    2017-05-01

    Most of the current evolutionary algorithms for constrained optimization algorithm are low computational efficiency. In order to improve efficiency, an improved differential evolution with shrinking space technique and adaptive trade-off model, named ATMDE, is proposed to solve constrained optimization problems. The proposed ATMDE algorithm employs an improved differential evolution as the search optimizer to generate new offspring individuals into evolutionary population. For the constraints, the adaptive trade-off model as one of the most important constraint-handling techniques is employed to select better individuals to retain into the next population, which could effectively handle multiple constraints. Then the shrinking space technique is designed to shrink the search region according to feedback information in order to improve computational efficiency without losing accuracy. The improved DE algorithm introduces three different mutant strategies to generate different offspring into evolutionary population. Moreover, a new mutant strategy called "DE/rand/best/1" is constructed to generate new individuals according to the feasibility proportion of current population. Finally, the effectiveness of the proposed method is verified by a suite of benchmark functions and practical engineering problems. This research presents a constrained evolutionary algorithm with high efficiency and accuracy for constrained optimization problems.

  17. Constraining the evolution of the Hubble Parameter using cosmic chronometer

    Science.gov (United States)

    Scarlata, Claudia; Dickinson, Hugh

    2018-01-01

    The Lambda-CDM model of Big Bang cosmology relies heavily on the assumption that two components - dark energy and dark matter - encompass 95% of the energy density of the Universe. Despite the dominant influence of these components, their nature is still entirely unknown.We present the initial results from a project that aims to provide new insights regarding the Dark Energy component. We do this by deriving independent constraints on the time-evolution of the Hubble parameter (H_0) using the “cosmic chronometer” method.By analyzing the HST NIR spectra from a large archival sample of passively evolving galaxies in distinct redshift bins between 1.3 and 2 we measure the typical stellar population ages (A) for the galaxies in each bin. The differential evolution of stellar population age with redshift (dA/dz) can be used to infer the corresponding evolution of H_0 which will provide important constraints on the nature of Dark Energy and its equation of state.

  18. Galaxy Evolution Over the Past Eleven Billion Years

    DEFF Research Database (Denmark)

    Man, Wing Shan

    they must undergo significant size evolution to become present-day giant ellipticals. The need for further evolution lends strong support to the idea that large galaxies form from hierarchal assembly, effective ruling out the monolithic collapse model. It is therefore important to understand the formation......Galaxy evolution studies have been revolutionized by the advent of near-infrared observations over the last decade. An intriguingly population of distant red galaxies, only visible at near-infrared wavelengths, was discovered. They were previously overlooked, since they are invisible even...... in the deepest Hubble Space Telescope (HST) optical surveys. Their stellar populations, characterized using deep near-infrared photometric and spectroscopic observations, reveal that they are the most massive and evolved galaxies at early epochs. This suggests that they have undergone a rapid build-up of stellar...

  19. Constraining supernova models using the hot gas in clusters of galaxies

    NARCIS (Netherlands)

    de Plaa, J.; Werner, N.; Bleeker, J.A.M.; Vink, J.; Kaastra, J.S.; Mendes, M.

    2009-01-01

    Context: The hot X-ray emitting gas in clusters of galaxies is a very large repository of metals produced by supernovae. During the evolution of clusters, billions of supernovae eject their material into this Intra-Cluster Medium (ICM). Aims: We aim to accurately measure the abundances in the ICM of

  20. The Evolution of Nearby Dwarf Galaxies

    NARCIS (Netherlands)

    Tolstoy, E.; Koleva, M; Prugniel, P; Vauglin,

    Within the Local Universe galaxies can be studied in great detail star by star. The Colour-Magnitude Diagram synthesis analysis method is well established as the most accurate way to determine the detailed star formation history of galaxies going back to the earliest times. This approach has

  1. Cosmic evolution and metal aversion in superluminous supernova host galaxies

    Science.gov (United States)

    Schulze, S.; Krühler, T.; Leloudas, G.; Gorosabel, J.; Mehner, A.; Buchner, J.; Kim, S.; Ibar, E.; Amorín, R.; Herrero-Illana, R.; Anderson, J. P.; Bauer, F. E.; Christensen, L.; de Pasquale, M.; de Ugarte Postigo, A.; Gallazzi, A.; Hjorth, J.; Morrell, N.; Malesani, D.; Sparre, M.; Stalder, B.; Stark, A. A.; Thöne, C. C.; Wheeler, J. C.

    2018-01-01

    The SUperluminous Supernova Host galaxIES survey aims to provide strong new constraints on the progenitors of superluminous supernovae (SLSNe) by understanding the relationship to their host galaxies. We present the photometric properties of 53 H-poor and 16 H-rich SLSN host galaxies out to z ∼ 4. We model their spectral energy distributions to derive physical properties, which we compare with other galaxy populations. At low redshift, H-poor SLSNe are preferentially found in very blue, low-mass galaxies with high average specific star formation rates. As redshift increases, the host population follows the general evolution of star-forming galaxies towards more luminous galaxies. After accounting for secular evolution, we find evidence for differential evolution in galaxy mass, but not in the B band and the far-ultraviolet luminosity (3σ confidence). Most remarkable is the scarcity of hosts with stellar masses above 1010 M⊙ for both classes of SLSNe. In case of H-poor SLSNe, we attribute this to a stifled production efficiency above ∼0.4 solar metallicity. However, we argue that, in addition to low metallicity, a short-lived stellar population is also required to regulate the SLSN production. H-rich SLSNe are found in a very diverse population of star-forming galaxies. Still, the scarcity of massive hosts suggests a stifled production efficiency above ∼0.8 solar metallicity. The large dispersion of the H-rich SLSNe host properties is in stark contrast to those of gamma-ray burst, regular core-collapse SN, and H-poor SLSNe host galaxies. We propose that multiple progenitor channels give rise to this subclass.

  2. Looking Wider and Further: The Evolution of Galaxies Inside Galaxy Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuanyuan [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-01-01

    Galaxy clusters are rare objects in the universe, but on-going wide field optical surveys are identifying many thousands of them to redshift 1.0 and beyond. Using early data from the Dark Energy Survey (DES) and publicly released data from the Sloan Digital Sky Survey (SDSS), this dissertation explores the evolution of cluster galaxies in the redshift range from 0 to 1.0. As it is common for deep wide field sky surveys like DES to struggle with galaxy detection efficiency at cluster core, the first component of this dissertation describes an efficient package that helps resolving the issue. The second part focuses on the formation of cluster galaxies. The study quantifies the growth of cluster bright central galaxies (BCGs), and argues for the importance of merging and intra-cluster light production during BCG evolution. An analysis of cluster red sequence galaxy luminosity function is also performed, demonstrating that the abundance of these galaxies is mildly dependent on cluster mass and redshift. The last component of the dissertation characterizes the properties of galaxy filaments to help understanding cluster environments

  3. Galaxy Evolution with Stellar Disks, Halos, and Streams in Nearby Galaxies

    Science.gov (United States)

    Staudaher, Shawn M.

    This thesis begins with a deep-dive into the stellar properties of the nearby spiral galaxy, M 63, a member of the EDGES (Extended Disk Galaxy Exploration Science) survey. Deep ( 28 AB mag arcsec-2) 3.6 mum imaging from the Spitzer Space Telescope reveals that the spiral structure of this galaxy is enveloped by an extended stellar halo, the result of the accretion of smaller galaxies. The mass of this stellar halo agrees well with results from the latest large scale LambdaCDM based galaxy evolution models. M 63 is also host to a tidal stream, an actively accreting satellite. The mass of the progenitor satellite is large enough that only sixteen similarly sized accretion events would account for the mass in the stellar halo. In addition, the majority of satellite accretion must have happened in the past as the average accretion rate derived from the stellar halo is significantly larger than the average accretion rate derived from the more recent tidal stream. The scope of the thesis is then extended to include the full sample of 92 nearby galaxies from EDGES. This is the largest Spitzer Space Telescope survey to probe the extended stellar properties of nearby galaxies. The surface brightness profiles of EDGES galaxies contain an unprecedented number of breaks (transitions from one galactic component to the next) given the sample size of EDGES, proving that studies of break statistics are incomplete without significantly deep imaging. The surface brightness profiles are decomposed into their individual components and the stellar mass for each component is measured. Seven galaxies contain strong evidence for the presence of stellar halos, and the masses of these halos agree with predictions from LambdaCDM based galaxy evolution models. However, the lack of stellar halos in general may be evidence that simulations continue to suffer from the so-called "missing satellite problem", where the number of satellite galaxies is overpredicted compared to observations.

  4. Role of Massive Stars in the Evolution of Primitive Galaxies

    Science.gov (United States)

    Heap, Sara

    2012-01-01

    An important factor controlling galaxy evolution is feedback from massive stars. It is believed that the nature and intensity of stellar feedback changes as a function of galaxy mass and metallicity. At low mass and metallicity, feedback from massive stars is mainly in the form of photoionizing radiation. At higher mass and metallicity, it is in stellar winds. IZw 18 is a local blue, compact dwarf galaxy that meets the requirements for a primitive galaxy: low halo mass greater than 10(exp 9)Msun, strong photoionizing radiation, no galactic outflow, and very low metallicity,log(O/H)+12=7.2. We will describe the properties of massive stars and their role in the evolution of IZw 18, based on analysis of ultraviolet images and spectra obtained with HST.

  5. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof......Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... is important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function...

  6. Dark Sage: Semi-analytic model of galaxy evolution

    Science.gov (United States)

    Stevens, Adam R. H.; Croton, Darren J.; Mutch, Simon J.; Sinha, Manodeep

    2017-06-01

    DARK SAGE is a semi-analytic model of galaxy formation that focuses on detailing the structure and evolution of galaxies' discs. The code-base, written in C, is an extension of SAGE (ascl:1601.006) and maintains the modularity of SAGE. DARK SAGE runs on any N-body simulation with trees organized in a supported format and containing a minimum set of basic halo properties.

  7. Internal and environmental secular evolution of disk galaxies

    Science.gov (United States)

    Kormendy, John

    2015-03-01

    This Special Session is devoted to the secular evolution of disk galaxies. Here `secular' means `slow' i.e., evolution on time scales that are generally much longer than the galaxy crossing or rotation time. Internal and environmentally driven evolution both are covered. I am indebted to Albert Bosma for reminding me at the 2011 Canary Islands Winter School on Secular Evolution that our subject first appeared in print in a comment made by Ivan King (1977) in his introductory talk at the Yale University meeting on The Evolution of Galaxies and Stellar Populations: `John Kormendy would like us to consider the possibility that a galaxy can interact with itself.. . . I'm not at all convinced, but John can show you some interesting pictures.' Two of the earliest papers that followed were Kormendy (1979a, b); the first discusses the interaction of galaxy components with each other, and the second studies these phenomena in the context of a morphological survey of barred galaxies. The earliest modeling paper that we still use regularly is Combes & Sanders (1981), which introduces the now well known idea that box-shaped bulges in edge-on galaxies are side-on, vertically thickened bars. It is gratifying to see how this subject has grown since that time. Hundreds of papers have been written, and the topic features prominently at many meetings (e.g., Block et al. 2004; Falcoń-Barroso & Knapen 2012, and this Special Session). My talk here introduces both internal and environmental secular evolution; a brief abstract follows. My Canary Islands Winter School review covers both subjects in more detail (Kormendy 2012). Kormendy & Kennicutt (2004) is a comprehensive review of internal secular evolution, and Kormendy & Bender (2012) covers environmental evolution. Both of these subject make significant progress at this meeting. Secular evolution happens because self-gravitating systems evolve toward the most tightly bound configuration that is reachable by the evolution processes

  8. Constraining the evolution of the Hubble Parameter using cosmic chronometers

    Science.gov (United States)

    Dickinson, Hugh

    2017-08-01

    Substantial investment is being made in space- and ground-based missions with the goal of revealing the nature of the observed cosmic acceleration. This is one of the most important unsolved problems in cosmology today.We propose here to constrain the evolution of the Hubble parameter [H(z)] between 1.3 grisms data obtained by the WISP, 3D-HST+AGHAST, FIGS, and CLEAR surveys will yield a sample of 140 suitable standard clocks, expanding existing samples by a factor of five. These additional data will enable us to improve existing constraints on the evolution of H at high redshift, and insodoing to better understand the fundamental nature of dark energy.

  9. Estimating precise metallicity and stellar mass evolution of galaxies

    Science.gov (United States)

    Mosby, Gregory

    2018-01-01

    The evolution of galaxies can be conveniently broken down into the evolution of their contents. The changing dust, gas, and stellar content in addition to the changing dark matter potential and periodic feedback from a super-massive blackhole are some of the key ingredients. We focus on the stellar content that can be observed, as the stars reflect information about the galaxy when they were formed. We approximate the stellar content and star formation histories of unresolved galaxies using stellar population modeling. Though simplistic, this approach allows us to reconstruct the star formation histories of galaxies that can be used to test models of galaxy formation and evolution. These models, however, suffer from degeneracies at large lookback times (t > 1 Gyr) as red, low luminosity stars begin to dominate a galaxy’s spectrum. Additionally, degeneracies between stellar populations at different ages and metallicities often make stellar population modeling less precise. The machine learning technique diffusion k-means has been shown to increase the precision in stellar population modeling using a mono-metallicity basis set. However, as galaxies evolve, we expect the metallicity of stellar populations to vary. We use diffusion k-means to generate a multi-metallicity basis set to estimate the stellar mass and chemical evolution of unresolved galaxies. Two basis sets are formed from the Bruzual & Charlot 2003 and MILES stellar population models. We then compare the accuracy and precision of these models in recovering complete (stellar mass and metallicity) histories of mock data. Similarities in the groupings of stellar population spectra in the diffusion maps for each metallicity hint at fundamental age transitions common to both basis sets that can be used to identify stellar populations in a given age range.

  10. Galaxy Evolution at the Frontier: The Rate of Galaxy Buildup Between z~11 and z~8

    Science.gov (United States)

    Bradley, Larry

    2013-10-01

    Understanding the evolution of early galaxies and their contribution to reionization has been a longstanding goal of observational astronomy. Hubble's WFC3/IR camera has revolutionized our knowledge of 7 8 galaxies due to their faint luminosities {M*> -20.3} and low volume densities. In particular, blank-field studies suggest a very dramatic buildup in cosmic star-formation rate density {SFRD} in the 165 Myr between z 8-10. These results are in tension with lensed-field studies which suggest a smooth buildup of galaxies from z 10 to 4. To distinguish between these scenarios, deeper observations are required to increase z > 9 number statistics and to reduce the significant cosmic variance due to a single blank field with sufficient depth {UDF + surrounding regions}. The upcoming HST Frontier Fields {HSTFF} program will obtain ultra deep observations of both "blank" and cluster-lensed fields. The latter are more efficient for high-z searches but introduce magnification uncertainties which we have quantified and found to be subdominant to Poisson uncertainties. Based on the archival first-year HSTFF data, we will identify a large sample of 35-54 galaxies at 89 galaxy evolution and placing new constraints on reionization. Additionally, we will measure the rest-frame UV continuum slopes of z 6-8 galaxies to improve dust extinction estimates at high redshift, a key ingredient in SFRD measurements. We will also perform strong lensing analyses to produce some of the highest resolution cluster dark matter maps to date.

  11. 60 micron luminosity evolution of rich clusters of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, D.M.; Rieke, G.H. (Steward Observatory, Tucson, AZ (USA))

    1990-10-01

    The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range. 38 refs.

  12. Formation and evolution of star clusters and their host galaxies

    NARCIS (Netherlands)

    Kruijssen, J.M.D.

    2011-01-01

    The vast majority of galaxies contains large populations of stellar clusters, which are bound groups of a few tens to millions of stars. A cluster is formed from a single giant molecular cloud and therefore its stars share the same age and chemical composition. The formation and evolution of star

  13. Chemical Evolution of Mn in Three Dwarf Spheroidal Galaxies

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Based on an improved model, more reasonable nucleosyn-thesis and explosion rate of SNeIa and CCSNe, we studied Mn evolution for three local dwarf spheroidal galaxies (dSphs), considering the detailed SNe yield and explosion rates for different types of progenitors. The results can explain the main ...

  14. Multiple Sclerosis Lesion Detection Using Constrained GMM and Curve Evolution

    Directory of Open Access Journals (Sweden)

    Oren Freifeld

    2009-01-01

    Full Text Available This paper focuses on the detection and segmentation of Multiple Sclerosis (MS lesions in magnetic resonance (MRI brain images. To capture the complex tissue spatial layout, a probabilistic model termed Constrained Gaussian Mixture Model (CGMM is proposed based on a mixture of multiple spatially oriented Gaussians per tissue. The intensity of a tissue is considered a global parameter and is constrained, by a parameter-tying scheme, to be the same value for the entire set of Gaussians that are related to the same tissue. MS lesions are identified as outlier Gaussian components and are grouped to form a new class in addition to the healthy tissue classes. A probability-based curve evolution technique is used to refine the delineation of lesion boundaries. The proposed CGMM-CE algorithm is used to segment 3D MRI brain images with an arbitrary number of channels. The CGMM-CE algorithm is automated and does not require an atlas for initialization or parameter learning. Experimental results on both standard brain MRI simulation data and real data indicate that the proposed method outperforms previously suggested approaches, especially for highly noisy data.

  15. Disk galaxy formation and evolution: models up to intermediate redshifts

    Science.gov (United States)

    Firmani, Claudio; Avila-Reese, Vladimir

    1999-06-01

    Making use of a seminumerical method we develop a scenario of disk galaxy formation and evolution in the framework of inflationary cold dark matter (CDM) cosmologies. Within the virializing dark matter halos, disks in centrifugal equilibrium are built-up and their galactic evolution is followed through an approach which considers the gravitational interactions among the galaxy components, the turbulence and energy balance of the ISM, the star formation (SF) process due to disk gravitational instabilities, the stellar evolution and the secular formation of a bulge. We find that the main properties and correlations of disk galaxies are determined by the mass, the hierarchical mass aggregation history and the primordial angular momentum. The models follow the same trends across the Hubble sequence than the observed galaxies. The predicted TF relation is in good agreement with the observations except for the standart CDM. While the slope of this relation remains almost constant up to intermediate redshifts, its zero-point decreases in the H-band and slightly increases in the B-band. A maximum in the SF rate for most of the models is attained at z ~1.5-2.5.

  16. Generative Models in Deep Learning: Constraints for Galaxy Evolution

    Science.gov (United States)

    Turp, Maximilian Dennis; Schawinski, Kevin; Zhang, Ce; Weigel, Anna K.

    2018-01-01

    New techniques are essential to make advances in the field of galaxy evolution. Recent developments in the field of artificial intelligence and machine learning have proven that these tools can be applied to problems far more complex than simple image recognition. We use these purely data driven approaches to investigate the process of star formation quenching. We show that Variational Autoencoders provide a powerful method to forward model the process of galaxy quenching. Our results imply that simple changes in specific star formation rate and bulge to disk ratio cannot fully describe the properties of the quenched population.

  17. Variable Cultural Acquisition Costs Constrain Cumulative Cultural Evolution

    Science.gov (United States)

    Mesoudi, Alex

    2011-01-01

    One of the hallmarks of the human species is our capacity for cumulative culture, in which beneficial knowledge and technology is accumulated over successive generations. Yet previous analyses of cumulative cultural change have failed to consider the possibility that as cultural complexity accumulates, it becomes increasingly costly for each new generation to acquire from the previous generation. In principle this may result in an upper limit on the cultural complexity that can be accumulated, at which point accumulated knowledge is so costly and time-consuming to acquire that further innovation is not possible. In this paper I first review existing empirical analyses of the history of science and technology that support the possibility that cultural acquisition costs may constrain cumulative cultural evolution. I then present macroscopic and individual-based models of cumulative cultural evolution that explore the consequences of this assumption of variable cultural acquisition costs, showing that making acquisition costs vary with cultural complexity causes the latter to reach an upper limit above which no further innovation can occur. These models further explore the consequences of different cultural transmission rules (directly biased, indirectly biased and unbiased transmission), population size, and cultural innovations that themselves reduce innovation or acquisition costs. PMID:21479170

  18. The formation and evolution of high-redshift dusty galaxies

    Science.gov (United States)

    Ma, Jingzhe; Gonzalez, Anthony H.; Ge, Jian; Vieira, Joaquin D.; Prochaska, Jason X.; Spilker, Justin; Strandet, Maria; Ashby, Matthew; Noterdaeme, Pasquier; Lundgren, Britt; Zhao, Yinan; Ji, Tuo; Zhang, Shaohua; Caucal, Paul; SPT SMG Collaboration

    2017-01-01

    Star formation and chemical evolution are among the biggest questions in galaxy formation and evolution. High-redshift dusty galaxies are the best sites to investigate mass assembly and growth, star formation rates, star formation history, chemical enrichment, and physical conditions. My thesis is based on two populations of high-redshift dusty galaxies, submillimeter galaxies (SMGs) and quasar 2175 Å dust absorbers, which are selected by dust emission and dust absorption, respectively.For the SMG sample, I have worked on the gravitationally lensed dusty, star-forming galaxies (DSFGs) at 2.8 thesis is focused on the stellar masses and star formation rates of these objects by means of multi-wavelength spectral energy distribution (SED) modelling. The data include HST/WFC3, Spitzer/IRAC, Herschel/PACS, Herschel/SPIRE, APEX/Laboca and SPT. Compared to the star-forming main sequence (MS), these DSFGs have specific SFRs that lie above the MS, suggesting that we are witnessing ongoing strong starburst events that may be driven by major mergers. SPT0346-52 at z = 5.7, the most extraordinary source in the SPT survey for which we obtained Chandra X-ray and ATCA radio data, was confirmed to have the highest star formation surface density of any known galaxy at high-z.The other half of my thesis is focused on a new population of quasar absorption line systems, 2175 Å dust absorbers, which are excellent probes of gas and dust properties, chemical evolution and physical conditions in the absorbing galaxies. This sample was selected from the SDSS and BOSS surveys and followed up with the Echelle Spectrographs and Imager on the Keck-II telescope, the Red & Blue Channel Spectrograph on the Multiple Mirror Telescope, and the Ultraviolet and Visible Echelle Spectrograph onboard the Very Large Telescope. We found a correlation between the presence of the 2175 Å bump and other ingredients including high metallicity, high depletion level, overall low ionization state of gas, neutral

  19. Variable Stars in (Not Only) Dwarf Galaxies: Key Tools to Constrain Distances and Stellar Content

    Science.gov (United States)

    Fiorentino, G.

    2011-07-01

    The important role of Cepheid and RR Lyrae variable stars and what they teach us about dwarf galaxies is discussed. Despite ever improving star formation histories of Local Group dwarf galaxies uncertainties remain, in particular in the identification and characterisation of the oldest stellar populations. The old stellar populations sometimes can be hard to interpret, or even to detect, due to their inherent faintness and scarcity, and often a strong overlying young population makes the crowding due to much brighter stars difficult to overcome. Recent and some preliminary results for RR Lyrae searches (in M 32 and Leo A) carried out with HST and Gemini-North/GMOS are presented. In these cases variables represent the only way to constrain the nature and, sometimes, the presence of a stellar population ≥10 Gyrs old. The recent discovery of Cepheids in I Zw 18 with HST is discussed. This allowed the first accurate distance determination, enabling a more secure detection of the Tip of the Red Giant Branch, and confirmed the existence of a population ≥2 Gyrs old.

  20. Topics in Galaxy Evolution: Early Star Formation and Quenching

    Science.gov (United States)

    Goncalves, Thiago Signorini

    In this thesis, we present three projects designed to shed light on yet unanswered questions on galaxy formation and evolution. The first two concern a sample of UV-bright starburst galaxies in the local universe (z ˜0.2). These objects are remarkably similar to star-forming galaxies that were abundant at high redshifts (2 manipulating our observations to mimic our objects at greater distances, we show how low resolution and signal-to-noise ratios can lead to erroneous conclusions, in particular when attempting to diagnose mergers as the origin of the starburst. Then, we present results from a pilot survey to study the cold, molecular gas reservoir in such objects. Again, we show that the observed properties are analogous to those observed at high redshift, in particular with respect to baryonic gas fractions in the galaxy, higher than normally found in low-extinction objects in the local universe. Furthermore, we show how gas surface density and star-formation surface density follow the same relation as local galaxies, albeit at much higher values. Finally, we discuss an observational project designed to measure the mass flux density from the blue sequence to the red sequence across the so-called green valley. We obtain the deepest spectra ever observed of green valley galaxies at intermediate redshifts (z˜0.8) in order to measure spectral features from which we can measure the star formation histories of individual galaxies. We measure a mass flux ratio that is higher than observed in the local universe, indicating the red sequence was growing faster when the universe was half its present age than today.

  1. Iron in galaxy groups and clusters: confronting galaxy evolution models with a newly homogenized data set

    Science.gov (United States)

    Yates, Robert M.; Thomas, Peter A.; Henriques, Bruno M. B.

    2017-01-01

    We present an analysis of the iron abundance in the hot gas surrounding galaxy groups and clusters. To do this, we first compile and homogenize a large data set of 79 low-redshift (tilde{z} = 0.03) systems (159 individual measurements) from the literature. Our analysis accounts for differences in aperture size, solar abundance, and cosmology, and scales all measurements using customized radial profiles for the temperature (T), gas density (ρgas), and iron abundance (ZFe). We then compare this data set to groups and clusters in the L-GALAXIES galaxy evolution model. Our homogenized data set reveals a tight T-ZFe relation for clusters, with a scatter in ZFe of only 0.10 dex and a slight negative gradient. After examining potential measurement biases, we conclude that some of this negative gradient has a physical origin. Our model suggests greater accretion of hydrogen in the hottest systems, via stripping from infalling satellites, as a cause. In groups, L-GALAXIES over-estimates ZFe, indicating that metal-rich gas removal (via e.g. AGN feedback) is required. L-GALAXIES is consistent with the observed ZFe in the intracluster medium (ICM) of the hottest clusters at z = 0, and shows a similar rate of ICM enrichment as that observed from at least z ˜ 1.3 to the present day. This is achieved without needing to modify any of the galactic chemical evolution (GCE) model parameters. However, the ZFe in intermediate-T clusters could be under-estimated in our model. We caution that modifications to the GCE modelling to correct this disrupt the agreement with observations of galaxies' stellar components.

  2. Molecules as tracers of galaxy evolution: an EMIR survey

    DEFF Research Database (Denmark)

    Costagliola, F.; Aalto, S.; I. Rodriguez, M.

    2011-01-01

    We investigate the molecular gas properties of a sample of 23 galaxies in order to find and test chemical signatures of galaxy evolution and to compare them to IR evolutionary tracers. Observation at 3 mm wavelengths were obtained with the EMIR broadband receiver, mounted on the IRAM 30 m telescope...... on Pico Veleta, Spain. We compare the emission of the main molecular species with existing models of chemical evolution by means of line intensity ratios diagrams and principal component analysis. We detect molecular emission in 19 galaxies in two 8 GHz-wide bands centred at 88 and 112 GHz. The main...... detected transitions are the J=1-0 lines of CO, 13CO, HCN, HNC, HCO+, CN, and C2H. We also detect HC3N J=10-9 in the galaxies IRAS 17208, IC 860, NGC 4418, NGC 7771, and NGC 1068. The only HC3N detections are in objects with HCO+/HCN 0.8). The brightest HC3N emission is found in IC 860, where we also...

  3. What drives the kinematic evolution of star-forming galaxies?

    Science.gov (United States)

    Hung, Chao-Ling

    2017-12-01

    One important result from recent large integral field spectrograph (IFS) surveys is that the intrinsic velocity dispersion of galaxies increases with redshift. Massive, rotationdominated discs are already in place at z ∼ 2, but they are dynamically hotter than spiral galaxies in the local Universe. Although several plausible mechanisms for this elevated velocity dispersion (e.g. star formation feedback, elevated gas supply, or more frequent galaxy interactions) have been proposed, the fundamental driver of the velocity dispersion enhancement at high redshift remains unclear. We investigate the origin of this kinematic evolution using a suite of cosmological simulations from the FIRE (Feedback In Realistic Environments) project. These simulations reproduce the observed trends between intrinsic velocity dispersion (σ intr), SFR, and z. In both the observed and simulated galaxies, σ intr is positively correlated with SFR. σ intr increases with redshift out to z ∼ 1 and then flattens beyond that. In the FIRE simulations, σ intr can vary significantly on timescales of ≲ 100 Myr. These variations closely mirror the time evolution of the SFR and gas inflow rate ( Ṁ gas). By cross-correlating pairs of σ intr Ṁ gas, and SFR, we show that the increased gas inflow leads to subsequent enhanced star formation, and enhancements in σ intr tend to temporally coincide with increases in Ṁ gas and SFR.

  4. Unsupervised Machine Learning to Track Galaxy Morphological Evolution in CANDELS

    Science.gov (United States)

    Peth, Michael; Lotz, J. M.; Freeman, P. E.; McPartland, C.; CANDELS Collaboration

    2014-01-01

    We use unsupervised machine learning techniques to study the evolution of galaxy morphology at 0 principal component analysis and diffusion mapping to study the correlations between concentraction (C), Gini coefficient (G), Asymmetry (A), the second-order moment of brightest 20% light (M_20), and three new statistics, Multi mode (M), Intensity (I) and Deviation (D). We measure these morphology statistics in 4 different HST wavebands: F160W (H), F125W, F814W and F606W. This allows us to consistently measure a single rest-frame passband across the redshift range. We discuss the implications for the evolution of the Hubble sequence and galaxy mergers over the last 10 billion years.

  5. Evolution of the K-band Galaxy Cluster Luminosity Function and Scaling Relations

    OpenAIRE

    Lin, Yen-Ting; Mohr, Joseph J.; Gonzalez, Anthony H.; Stanford, S Adam

    2006-01-01

    We study the evolution of two fundamental properties of galaxy clusters: the luminosity function (LF) and the scaling relations between the total galaxy number N (or luminosity) and cluster mass M. Using a sample of 27 clusters (0

  6. Chempy: A flexible chemical evolution model for abundance fitting. Do the Sun's abundances alone constrain chemical evolution models?

    Science.gov (United States)

    Rybizki, Jan; Just, Andreas; Rix, Hans-Walter

    2017-09-01

    Elemental abundances of stars are the result of the complex enrichment history of their galaxy. Interpretation of observed abundances requires flexible modeling tools to explore and quantify the information about Galactic chemical evolution (GCE) stored in such data. Here we present Chempy, a newly developed code for GCE modeling, representing a parametrized open one-zone model within a Bayesian framework. A Chempy model is specified by a set of five to ten parameters that describe the effective galaxy evolution along with the stellar and star-formation physics: for example, the star-formation history (SFH), the feedback efficiency, the stellar initial mass function (IMF), and the incidence of supernova of type Ia (SN Ia). Unlike established approaches, Chempy can sample the posterior probability distribution in the full model parameter space and test data-model matches for different nucleosynthetic yield sets. It is essentially a chemical evolution fitting tool. We straightforwardly extend Chempy to a multi-zone scheme. As an illustrative application, we show that interesting parameter constraints result from only the ages and elemental abundances of the Sun, Arcturus, and the present-day interstellar medium (ISM). For the first time, we use such information to infer the IMF parameter via GCE modeling, where we properly marginalize over nuisance parameters and account for different yield sets. We find that 11.6+ 2.1-1.6% of the IMF explodes as core-collapse supernova (CC-SN), compatible with Salpeter (1955, ApJ, 121, 161). We also constrain the incidence of SN Ia per 103M⊙ to 0.5-1.4. At the same time, this Chempy application shows persistent discrepancies between predicted and observed abundances for some elements, irrespective of the chosen yield set. These cannot be remedied by any variations of Chempy's parameters and could be an indication of missing nucleosynthetic channels. Chempy could be a powerful tool to confront predictions from stellar

  7. The Formation and Evolution of Star Clusters in Interacting Galaxies

    Science.gov (United States)

    Maji, Moupiya; Zhu, Qirong; Li, Yuexing; Charlton, Jane; Hernquist, Lars; Knebe, Alexander

    2017-08-01

    Observations of globular clusters show that they have universal lognormal mass functions with a characteristic peak at ˜ 2× {10}5 {M}⊙ , but the origin of this peaked distribution is highly debated. Here we investigate the formation and evolution of star clusters (SCs) in interacting galaxies using high-resolution hydrodynamical simulations performed with two different codes in order to mitigate numerical artifacts. We find that massive SCs in the range of ˜ {10}5.5{--}{10}7.5 {M}⊙ form preferentially in the highly shocked regions produced by galaxy interactions. The nascent cluster-forming clouds have high gas pressures in the range of P/k˜ {10}8{--}{10}12 {{K}} {{cm}}-3, which is ˜ {10}4{--}{10}8 times higher than the typical pressure of the interstellar medium but consistent with recent observations of a pre-super-SC cloud in the Antennae Galaxies. Furthermore, these massive SCs have quasi-lognormal initial mass functions with a peak around ˜ {10}6 {M}⊙ . The number of clusters declines with time due to destructive processes, but the shape and the peak of the mass functions do not change significantly during the course of galaxy collisions. Our results suggest that gas-rich galaxy mergers may provide a favorable environment for the formation of massive SCs such as globular clusters, and that the lognormal mass functions and the unique peak may originate from the extreme high-pressure conditions of the birth clouds and may survive the dynamical evolution.

  8. Galaxy rotation and supermassive black hole binary evolution

    Science.gov (United States)

    Mirza, M. A.; Tahir, A.; Khan, F. M.; Holley-Bockelmann, H.; Baig, A. M.; Berczik, P.; Chishtie, F.

    2017-09-01

    Supermassive black hole (SMBH) binaries residing at the core of merging galaxies are recently found to be strongly affected by the rotation of their host galaxies. The highly eccentric orbits that form when the host is counterrotating emit strong bursts of gravitational waves that propel rapid SMBH binary coalescence. Most prior work, however, focused on planar orbits and a uniform rotation profile, an unlikely interaction configuration. However, the coupling between rotation and SMBH binary evolution appears to be such a strong dynamical process that it warrants further investigation. This study uses direct N-body simulations to isolate the effect of galaxy rotation in more realistic interactions. In particular, we systematically vary the SMBH orbital plane with respect to the galaxy rotation axis, the radial extent of the rotating component, and the initial eccentricity of the SMBH binary orbit. We find that the initial orbital plane orientation and eccentricity alone can change the inspiral time by an order of magnitude. Because SMBH binary inspiral and merger is such a loud gravitational wave source, these studies are critical for the future gravitational wave detector, Laser Interferometer Space Antenna, an ESA/NASA mission currently set to launch by 2034.

  9. CANDELS: A Cosmic Quest for Distant Galaxies Offering Live Views of Galaxy Evolution

    Science.gov (United States)

    Koo, David C.; CANDELS

    2017-06-01

    For decades, the study of distant galaxies has been pushing the frontiers of extra-galactic research, with observations from the best suite of telescopes and instruments and with theory from the most advanced computer simulations. This talk will focus on observations taken within the CANDELS fields to reveal the richness and complexity of this still-growing field. CANDELS (Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey) itself is the largest project ever taken by Hubble and is composed of optical and near-infrared images of five tiny regions of sky containing over 200,000 distant galaxies. All these regions, two of which are GOODS North and South, were already outstanding in possessing years of prior surveys taken by many teams worldwide and have continued to attract more and better spectra and panchromatic images from Keck, Hubble, Chandra, Spitzer, and other telescopes ranging from X-ray to radio. Combined together, the rich data within the CANDELS fields offer live views of galaxy evolution from “Cosmic Dawn” when the first infant galaxies and cosmic black holes were born, through “Cosmic Noon” during the peak of galaxy and black hole growth, and then to “Cosmic Afternoon” when star formation and black hole activities, morphologies, motions, and contents settled to those of our Milky Way and its zoo of cousins today. The talk will highlight some interesting discoveries from the last two periods and close with new mysteries challenging our field in the 21st century and future prospects for solving them.

  10. Evolution of dust extinction curves in galaxy simulation

    Science.gov (United States)

    Hou, Kuan-Chou; Hirashita, Hiroyuki; Nagamine, Kentaro; Aoyama, Shohei; Shimizu, Ikkoh

    2017-07-01

    To understand the evolution of extinction curve, we calculate the dust evolution in a galaxy using smoothed particle hydrodynamic simulations incorporating stellar dust production, dust destruction in supernova shocks, grain growth by accretion and coagulation, and grain disruption by shattering. The dust species are separated into carbonaceous dust and silicate. The evolution of grain size distribution is considered by dividing grain population into large and small grains, which allows us to estimate extinction curves. We examine the dependence of extinction curves on the position, gas density and metallicity in the galaxy, and find that extinction curves are flat at t ≲ 0.3 Gyr because stellar dust production dominates the total dust abundance. The 2175 Å bump and far-ultraviolet (FUV) rise become prominent after dust growth by accretion. At t ≳ 3 Gyr, shattering works efficiently in the outer disc and low-density regions, so extinction curves show a very strong 2175 Å bump and steep FUV rise. The extinction curves at t ≳ 3 Gyr are consistent with the Milky Way extinction curve, which implies that we successfully included the necessary dust processes in the model. The outer disc component caused by stellar feedback has an extinction curve with a weaker 2175 Å bump and flatter FUV slope. The strong contribution of carbonaceous dust tends to underproduce the FUV rise in the Small Magellanic Cloud extinction curve, which supports selective loss of small carbonaceous dust in the galaxy. The snapshot at young ages also explains the extinction curves in high-redshift quasars.

  11. Evolution of Field Spiral Galaxies up to Redshifts z = 1

    Science.gov (United States)

    Böhm, Asmus; Ziegler, Bodo L.

    2007-10-01

    We have gained intermediate-resolution spectroscopy with the FORS instruments of the Very Large Telescope (VLT) and high-resolution imaging with the Advanced Camera for Surveys aboard HST for a sample of 220 distant field spiral galaxies within the FORS Deep Field and William Herschel Deep Field. Spatially resolved rotation curves were extracted and fitted with synthetic velocity fields that take into account all geometric and observational effects, such as blurring due to the slit width and seeing influence. Using these fits, the maximum rotation velocity Vmax could be determined for 124 galaxies that cover the redshift range 0.1zz TFR would be in compliance if its scatter decreased by more than a factor of 3 between z~0.5 and 0. Accepting this large evolution of the TFR scatter, we hence find no strong evidence for a mass- or luminosity-dependent evolution of disk galaxies. On the other hand, we derive stellar mass-to-luminosity ratios (M/L) that indicate a luminosity-dependent evolution in the sense that distant low-luminosity disks have much lower M/L than their local counterparts, while high-luminosity disks barely evolved in M/L over the covered redshift range. This could be the manifestation of the ``downsizing'' effect, i.e., the successive shift of the peak of star formation from high-mass to low-mass galaxies toward lower redshifts. This trend might be canceled out in the TF diagram due to the simultaneous evolution of multiple parameters. We also estimate the ratios between stellar and total masses, finding that these remained constant since z=1, as would be expected in the context of hierarchically growing structure. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile (ESO nos. 65.O-0049, 66.A-0547, 68.A-0013, 69.B-0278B, and 70.B-0251A) and observations with the NASA/ESA Hubble Space Telescope, PID 9502 and 9908.

  12. H2 MAGIE: H2 as a Major Agent to Galaxy Interaction and Evolution

    Science.gov (United States)

    Guillard, Pierre

    2010-01-01

    Spitzer space telescope spectroscopy reveal a new class of H2-luminous galaxies with enhanced H2 line emission, but where star formation is strongly suppressed. This is in sharp contrast with what is observed in standard star forming galaxies. These sources are all in active phases of galaxy evolution (galaxy interactions, AGN feedback, gas accretion in galaxy clusters, etc.). Why is H2 present in violent phases of galaxy evolution? How is the H2 emission powered? Why is the H2 gas inefficient at forming stars? What can we learn from these "H2 galaxies" about galaxy formation? This thesis addresses these questions, and discuss the theoretical and observational perspectives of this work (in particular Herschel and JWST).

  13. Dynamical evolution of globular-cluster systems in clusters of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Muzzio, J.C.

    1987-04-01

    The dynamical processes that affect globular-cluster systems in clusters of galaxies are analyzed. Two-body and impulsive approximations are utilized to study dynamical friction, drag force, tidal stripping, tidal radii, globular-cluster swapping, tidal accretion, and galactic cannibalism. The evolution of galaxies and the collision of galaxies are simulated numerically; the steps involved in the simulation are described. The simulated data are compared with observations. Consideration is given to the number of galaxies, halo extension, location of the galaxies, distribution of the missing mass, nonequilibrium initial conditions, mass dependence, massive central galaxies, globular-cluster distribution, and lost globular clusters. 116 references.

  14. THE EVOLUTION OF BRIGHTEST CLUSTER GALAXIES IN A HIERARCHICAL UNIVERSE

    Energy Technology Data Exchange (ETDEWEB)

    Tonini, Chiara; Bernyk, Maksym; Croton, Darren [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, VIC 3122 (Australia); Maraston, Claudia; Thomas, Daniel [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom)

    2012-11-01

    We investigate the evolution of brightest cluster galaxies (BCGs) from redshift z {approx} 1.6 to z = 0. We upgrade the hierarchical semi-analytic model of Croton et al. with a new spectro-photometric model that produces realistic galaxy spectra, making use of the Maraston stellar populations and a new recipe for the dust extinction. We compare the model predictions of the K-band luminosity evolution and the J - K, V - I, and I - K color evolution with a series of data sets, including those of Collins et al. who argued that semi-analytic models based on the Millennium simulation cannot reproduce the red colors and high luminosity of BCGs at z > 1. We show instead that the model is well in range of the observed luminosity and correctly reproduces the color evolution of BCGs in the whole redshift range up to z {approx} 1.6. We argue that the success of the semi-analytic model is in large part due to the implementation of a more sophisticated spectro-photometric model. An analysis of the model BCGs shows an increase in mass by a factor of 2-3 since z {approx} 1, and star formation activity down to low redshifts. While the consensus regarding BCGs is that they are passively evolving, we argue that this conclusion is affected by the degeneracy between star formation history and stellar population models used in spectral energy distribution fitting, and by the inefficacy of toy models of passive evolution to capture the complexity of real galaxies, especially those with rich merger histories like BCGs. Following this argument, we also show that in the semi-analytic model the BCGs show a realistic mix of stellar populations, and that these stellar populations are mostly old. In addition, the age-redshift relation of the model BCGs follows that of the universe, meaning that given their merger history and star formation history, the ageing of BCGs is always dominated by the ageing of their stellar populations. In a {Lambda}CDM universe, we define such evolution as &apos

  15. Constrained pattern of viral evolution in acute and early HCV infection limits viral plasticity

    National Research Council Canada - National Science Library

    Pfafferott, Katja; Gaudieri, Silvana; Ulsenheimer, Axel; James, Ian; Heeg, Malte; Nolan, David; John, Mina; Rauch, Andri; Mallal, Simon; Lucas, Andrew; Klenerman, Paul; Diepolder, Helmut M; Lucas, Michaela

    2011-01-01

    .... Most mutations were maintained into the chronic phase of HCV infection (75%). The lack of reversion of adaptations and high proportion of silent substitutions suggests that HCV has structural and functional limitations that constrain evolution...

  16. Dust evolution with active galactic nucleus feedback in elliptical galaxies

    Science.gov (United States)

    Hirashita, Hiroyuki; Nozawa, Takaya

    2017-12-01

    We have recently suggested that dust growth in the cold gas phase dominates the dust abundance in elliptical galaxies while dust is efficiently destroyed in the hot X-ray emitting plasma (hot gas). In order to understand the dust evolution in elliptical galaxies, we construct a simple model that includes dust growth in the cold gas and dust destruction in the hot gas. We also take into account the effect of mass exchange between these two gas components induced by active galactic nucleus (AGN) feedback. We survey reasonable ranges of the relevant parameters in the model and find that AGN feedback cycles actually produce a variety in cold gas mass and dust-to-gas ratio. By comparing with an observational sample of nearby elliptical galaxies, we find that, although the dust-to-gas ratio varies by an order of magnitude in our model, the entire range of the observed dust-to-gas ratios is difficult to be reproduced under a single parameter set. Variation of the dust growth efficiency is the most probable solution to explain the large variety in dust-to-gas ratio of the observational sample. Therefore, dust growth can play a central role in creating the variation in dust-to-gas ratio through the AGN feedback cycle and through the variation in dust growth efficiency.

  17. Constraining the galaxy-halo connection over the last 13.3 Gyr: star formation histories, galaxy mergers and structural properties

    Science.gov (United States)

    Rodríguez-Puebla, Aldo; Primack, Joel R.; Avila-Reese, Vladimir; Faber, S. M.

    2017-09-01

    We present new determinations of the stellar-to-halo mass relation (SHMR) at z = 0-10 that match the evolution of the galaxy stellar mass function, the star formation rate (SFR)-M* relation and the cosmic SFR. We utilize a compilation of 40 observational studies from the literature and correct them for potential biases. Using our robust determinations of halo mass assembly and the SHMR, we infer star formation histories, merger rates and structural properties for average galaxies, combining star-forming and quenched galaxies. Our main findings are as follows: (1) The halo mass M50 above which 50 per cent of galaxies are quenched coincides with sSFR/sMAR ˜ 1, where sSFR is the specific SFR and sMAR is the specific halo mass accretion rate. (2) M50 increases with redshift, presumably due to cold streams being more efficient at high redshifts, while virial shocks and active galactic nucleus feedback become more relevant at lower redshifts. (3) The ratio sSFR/sMAR has a peak value, which occurs around {M_vir}˜ 2× 10^{11} M_{⊙}. (4) The stellar mass density within 1 kpc, Σ1, is a good indicator of the galactic global sSFR. (5) Galaxies are statistically quenched after they reach a maximum in Σ1, consistent with theoretical expectations of the gas compaction model; this maximum depends on redshift. (6) In-situ star formation is responsible for most galactic stellar mass growth, especially for lower mass galaxies. (7) Galaxies grow inside-out. The marked change in the slope of the size-mass relation when galaxies became quenched, from d log {R_eff}/d log {M_*}˜ 0.35 to ˜2.5, could be the result of dry minor mergers.

  18. Size evolution of normal and compact galaxies in the EAGLE simulation

    Science.gov (United States)

    Furlong, M.; Bower, R. G.; Crain, R. A.; Schaye, J.; Theuns, T.; Trayford, J. W.; Qu, Y.; Schaller, M.; Berthet, M.; Helly, J. C.

    2017-02-01

    We present the evolution of galaxy sizes, from redshift 2 to 0, for actively star forming and passive galaxies in the cosmological hydrodynamical 1003 cMpc3 simulation of the EAGLE project. We find that the sizes increase with stellar mass, but that the relation weakens with increasing redshift. Separating galaxies by their star formation activity, we find that passive galaxies are typically smaller than active galaxies at a fixed stellar mass. These trends are consistent with those found in observations and the level of agreement between the predicted and observed size-mass relations is of the order of 0.1 dex for z < 1 and 0.2-0.3 dex from redshift 1 to 2. We use the simulation to compare the evolution of individual galaxies with that of the population as a whole. While the evolution of the size-stellar mass relation for active galaxies provides a good proxy for the evolution of individual galaxies, the evolution of individual passive galaxies is not well represented by the observed size-mass relation due to the evolving number density of passive galaxies. Observations of z ˜ 2 galaxies have revealed an abundance of massive red compact galaxies, which depletes below z ˜ 1. We find that a similar population forms naturally in the simulation. Comparing these galaxies with their z = 0 descendants, we find that all compact galaxies grow in size due to the high-redshift stars migrating outwards. Approximately 60 per cent of the compact galaxies increase in size further due to renewed star formation and/or mergers.

  19. THE TULLY-FISHER RELATION FOR LOW SURFACE BRIGHTNESS GALAXIES - IMPLICATIONS FOR GALAXY EVOLUTION

    NARCIS (Netherlands)

    Zwaan, M.A.; VAN DER HULST, JM; DE BLOK, WJG; MCGAUGH, SS

    1995-01-01

    We present the B-band Tully-Fisher relation for low surface brightness (LSB) galaxies. These LSB galaxies follow the same Tully-Fisher relation as normal spiral galaxies. This implies that the mass-to-light ratio (M/L) of LSB galaxies is typically a factor of 2 larger than that of normal galaxies of

  20. Crustal evolution at mantle depths constrained from Pamir xenoliths

    Science.gov (United States)

    Kooijman, E.; Hacker, B. R.; Smit, M. A.; Kylander-Clark, A. R.; Ratschbacher, L.

    2012-12-01

    Lower crustal xenoliths erupted in the Pamir at ~11 Ma provide an exclusive opportunity to study the evolution of crust at mantle depths during a continent-continent collision. To investigate, and constrain the timing of, the petrologic processes that occurred during burial to the peak conditions (2.5-2.8 GPa, 1000-1100 °C; [1]), we performed chemical- and isotope analyses of accessory minerals in 10 xenoliths, ranging from eclogites to grt-ky-qtz granulites. In situ laser ablation split-stream ICPMS yielded 1) U-Pb ages, Ti concentrations and REE in zircon, 2) U/Th-Pb ages and REE in monazite, and 3) U-Pb ages and trace elements in rutile. In addition, garnet, and biotite and K-feldspar were dated using Lu-Hf and 40Ar/39Ar geochronology, respectively. Zircon and monazite U-(Th-)Pb ages are 101.9±1.8, 53.7±1.0, 39.1±0.8, 21.7±0.4, 18.2±0.5, 16.9±0.8, 15.1±0.3 (2σ) and 12.5-11.1 Ma; most samples showed several or all of these populations. The 53.7 Ma and older ages are xenocrystic or detrital. For younger ages, zircon and monazite in individual samples recorded different ages-although zircon in one rock and monazite in another can be the same age. The 39.1 Ma zircon and monazite mostly occur as inclusions in minerals of the garnet-bearing assemblage that represents the early, low-P stages of burial. Garnet Lu-Hf ages of 37.8±0.3 Ma support garnet growth at this time. Spinifex-like textures containing 21.7-11.1 Ma zircon and monazite record short-lived partial melting events during burial. Aligned kyanite near these patches indicates associated deformation. Zircons yielding ≤12.5 Ma exhibit increased Eu/Eu* and markedly decreased HREE concentrations, interpreted to record feldspar breakdown and omphacite growth during increasing pressure. Rutile U-Pb cooling ages are 10.8±0.3 Ma in all samples. This agrees with the weighted mean 40Ar/39Ar age of eight biotite, K-feldspar and whole rock separates of 11.00+0.16/-0.09 Ma. Rutile in eclogites provides Zr

  1. Simulating Galaxy Clusters with Dust Formation and Evolution

    Science.gov (United States)

    Gjergo, Eda; Granato, Gian Luigi; Murante, Giuseppe; Ragone-Figueroa, Cinthia

    2017-07-01

    In order to investigate basic properties of galaxies, such as the star formation rate and the masses of baryonic components, it is important to account for dust reprocessing. Dust particles absorb and scatter the stars' optical/UV emission, and they re-radiate thermally in the infrared. A combination of simulations and post-processing radiative transfer computations can produce mock data, which can be compared directly to observations. Until now, however, dust properties have only been included in our simulations by means of post-processing assumptions, leaving room for uncertainties, particularly significant at wavelengths shorter than 100 microns. To reduce these uncertainties, we implemented a state-of-the-art treatment of the production and evolution of dust grains within our simulation code, P-GADGET3. This model traces the creation, evolution, and destruction of dust through various processes. It accounts for the diameter of dust particles with a two-grain-size approximation proposed by H. Hirashita. We will present a first result of our new code applied to zoom-in simulations of massive (M_{200} > 3 × 10^4 M_{⊙}) galaxy clusters, focusing in particular to the early stages of assembly of the cluster at high redshift, around z = 2, where the SF activity is at its maximum and the proto-cluster regions are rich of cold, dust-polluted gas.

  2. Gravitational-wave limits from pulsar timing constrain supermassive black hole evolution.

    Science.gov (United States)

    Shannon, R M; Ravi, V; Coles, W A; Hobbs, G; Keith, M J; Manchester, R N; Wyithe, J S B; Bailes, M; Bhat, N D R; Burke-Spolaor, S; Khoo, J; Levin, Y; Osłowski, S; Sarkissian, J M; van Straten, W; Verbiest, J P W; Wang, J-B

    2013-10-18

    The formation and growth processes of supermassive black holes (SMBHs) are not well constrained. SMBH population models, however, provide specific predictions for the properties of the gravitational-wave background (GWB) from binary SMBHs in merging galaxies throughout the universe. Using observations from the Parkes Pulsar Timing Array, we constrain the fractional GWB energy density (Ω(GW)) with 95% confidence to be Ω(GW)(H0/73 kilometers per second per megaparsec)(2) Simulation Project is inconsistent with our limit with 50% probability.

  3. The Fastest Galaxy Evolution in an Unbiased Compact Group Sample with WISE

    Science.gov (United States)

    Lee, Gwang-Ho; Hwang, Ho Seong; Sohn, Jubee; Lee, Myung Gyoon

    2017-02-01

    We study the mid-infrared (MIR) properties of galaxies in compact groups and their environmental dependence using the Wide-field Infrared Survey Explorer (WISE) data. We use a volume-limited sample of 670 compact groups and their 2175 member galaxies with {M}rSohn et al., which were identified using a friends-of-friends algorithm. Among the 2175 galaxies, 1541 galaxies are detected at WISE 12 μ {{m}} with a signal-to-noise ratio greater than 3. Among the 1541 galaxies, 433 AGN-host galaxies are identified by using both optical and MIR classification schemes. Using the remaining 1108 non-AGN galaxies, we find that the MIR [3.4]-[12] colors of compact group early-type galaxies are on average bluer than those of cluster early-type galaxies. When compact groups have both early- and late-type member galaxies, the MIR colors of the late-type members in those compact groups are bluer than the MIR colors of cluster late-type galaxies. As compact groups are located in denser regions, they tend to have larger early-type galaxy fractions and bluer MIR color galaxies. These trends are also seen for neighboring galaxies around compact groups. However, compact group member galaxies always have larger early-type galaxy fractions and bluer MIR colors than their neighboring galaxies. Our findings suggest that the properties of compact group galaxies depend on both internal and external environments of compact groups, and that galaxy evolution is faster in compact groups than in the central regions of clusters.

  4. Planetary characteristics constraining the advent and the evolution of life.

    Science.gov (United States)

    Ksanfomaliti, L. V.

    1995-10-01

    Very narrow limits of many physical characteristics of a terrestrial planet - primarily its mass and range of temperatures - are necessary for the advent and the evolution of an amino-nucleic-acid form of life and its transition into multicellular organisms. Only a favorable combination of many parameters can provide the conditions required for the advent of lifeforms and their evolution into conscious beings.

  5. Antibody evolution constrains conformational heterogeneity by tailoring protein dynamics.

    Science.gov (United States)

    Zimmermann, Jörg; Oakman, Erin L; Thorpe, Ian F; Shi, Xinghua; Abbyad, Paul; Brooks, Charles L; Boxer, Steven G; Romesberg, Floyd E

    2006-09-12

    The evolution of proteins with novel function is thought to start from precursor proteins that are conformationally heterogeneous. The corresponding genes may be duplicated and then mutated to select and optimize a specific conformation. However, testing this idea has been difficult because of the challenge of quantifying protein flexibility and conformational heterogeneity as a function of evolution. Here, we report the characterization of protein heterogeneity and dynamics as a function of evolution for the antifluorescein antibody 4-4-20. Using nonlinear laser spectroscopy, surface plasmon resonance, and molecular dynamics simulations, we demonstrate that evolution localized the Ab-combining site from a heterogeneous ensemble of conformations to a single conformation by introducing mutations that act cooperatively and over significant distances to rigidify the protein. This study demonstrates how protein dynamics may be tailored by evolution and has important implications for our understanding of how novel protein functions are evolved.

  6. SPICA and the Chemical Evolution of Galaxies: The Rise of Metals and Dust

    Science.gov (United States)

    Fernández-Ontiveros, J. A.; Armus, L.; Baes, M.; Bernard-Salas, J.; Bolatto, A. D.; Braine, J.; Ciesla, L.; De Looze, I.; Egami, E.; Fischer, J.; Giard, M.; González-Alfonso, E.; Granato, G. L.; Gruppioni, C.; Imanishi, M.; Ishihara, D.; Kaneda, H.; Madden, S.; Malkan, M.; Matsuhara, H.; Matsuura, M.; Nagao, T.; Najarro, F.; Nakagawa, T.; Onaka, T.; Oyabu, S.; Pereira-Santaella, M.; Pérez Fournon, I.; Roelfsema, P.; Santini, P.; Silva, L.; Smith, J.-D. T.; Spinoglio, L.; van der Tak, F.; Wada, T.; Wu, R.

    2017-11-01

    The physical processes driving the chemical evolution of galaxies in the last 11Gyr cannot be understood without directly probing the dust-obscured phase of star-forming galaxies and active galactic nuclei. This phase, hidden to optical tracers, represents the bulk of the star formation and black hole accretion activity in galaxies at 1 extinction and temperature. In this work, we investigate how SPICA observations could be exploited to understand key aspects in the chemical evolution of galaxies: the assembly of nearby galaxies based on the spatial distribution of heavy element abundances, the global content of metals in galaxies reaching the knee of the luminosity function up to z 3, and the dust composition of galaxies at high-z. Possible synergies with facilities available in the late 2020s are also discussed.

  7. Does environment affect the chemical evolution of star-forming galaxies?

    Science.gov (United States)

    Gupta, Anshu; Yuan, Tiantian; Kewley, Lisa; Tran, Kim-Vy; Martizzi, Davide; Torrey, Paul; Vogelsberger, Mark; Anshu Gupta

    2018-01-01

    Understanding the relative significance of gravitational and hydrodynamic interactions on the chemical evolution of cluster galaxies is fascinating and challenging. In this talk, I will present my observation of a cluster-scale gradient in the metallicity of star-forming galaxies as a complementary method to discern the impact of environment on chemical evolution. Our observations for MACS J1115+0129 show that cluster galaxies near the cluster center are more metal-rich compared to galaxies in the cluster outskirts. Using a semi-analytic model of ram pressure stripping, we prove that removal of low-metallicity gas is not sufficient to reproduce the metallicity gradient. I will also present our recent results from IllustrisTNG simulations predicting the "pre-enrichment" of progenitor cluster galaxies. Using tracer particles from IllustrisTNG simulations, we prove that inflow of enriched gas is the prime driver of the higher metal fraction in cluster galaxies compared to field galaxies.

  8. Using large impacts to constrain the thermal evolution of the terrestrial planets

    Science.gov (United States)

    Padovan, S.; Tosi, N.; Plesa, A.-C.; Ruedas, T.

    2017-09-01

    Thermal evolution models of the terrestrial planets are directly constrained by only few observations (nature, volume, and age of the crust). In this work we show how local data sets, pertaining to the volume and time of emplacement of volcanic material within large impact basins, can provide additional constraints on the global evolution of Mercury, Mars, and the Moon.

  9. A LINK TO THE PAST: USING MARKOV CHAIN MONTE CARLO FITTING TO CONSTRAIN FUNDAMENTAL PARAMETERS OF HIGH-REDSHIFT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Pirzkal, N.; Rothberg, B.; Koekemoer, Anton [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Nilsson, Kim K. [ST-ECF, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Muenchen (Germany); Finkelstein, S. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Malhotra, Sangeeta; Rhoads, James, E-mail: npirzkal@stsci.edu [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

    2012-04-01

    We have developed a new method for fitting spectral energy distributions (SEDs) to identify and constrain the physical properties of high-redshift (4 < z < 8) galaxies. Our approach uses an implementation of Bayesian based Markov Chain Monte Carlo that we have dubbed '{pi}MC{sup 2}'. It allows us to compare observations to arbitrarily complex models and to compute 95% credible intervals that provide robust constraints for the model parameters. The work is presented in two sections. In the first, we test {pi}MC{sup 2} using simulated SEDs to not only confirm the recovery of the known inputs but to assess the limitations of the method and identify potential hazards of SED fitting when applied specifically to high-redshift (z > 4) galaxies. In the second part of the paper we apply {pi}MC{sup 2} to thirty-three 4 < z < 8 objects, including the spectroscopically confirmed Grism ACS Program for Extragalactic Science Ly{alpha} sample (4 < z < 6), supplemented by newly obtained Hubble Space Telescope/WFC3 near-IR observations, and several recently reported broadband selected z > 6 galaxies. Using {pi}MC{sup 2}, we are able to constrain the stellar mass of these objects and in some cases their stellar age and find no evidence that any of these sources formed at a redshift larger than z = 8, a time when the universe was Almost-Equal-To 0.6 Gyr old.

  10. Constraining Dark Energy with X-ray Galaxy Clusters, Supernovae and the Cosmic Microwave Background

    Energy Technology Data Exchange (ETDEWEB)

    Rapetti, D

    2005-04-18

    We present new constraints on the evolution of dark energy from an analysis of Cosmic Microwave Background, supernova and X-ray galaxy cluster data. Our analysis employs a minimum of priors and exploits the complementary nature of these data sets. We examine a series of dark energy models with up to three free parameters: the current dark energy equation of state w{sub 0}, the early time equation of state w{sub et} and the scale factor at transition, a{sub t}. From a combined analysis of all three data sets, assuming a constant equation of state and that the Universe is flat, we measure w{sub 0} = 1.05{sub -0.12}{sup +0.10}. Including w{sub et} as a free parameter and allowing the transition scale factor to vary over the range 0.5 < a{sub t} < 0.95 where the data sets have discriminating power, we measure w{sub 0} = -1.27{sub -0.39}{sup +0.33} and w{sub et} = -0.66{sub -0.62}{sup +0.44}. We find no significant evidence for evolution in the dark energy equation of state parameter with redshift. Marginal hints of evolution in the supernovae data become less significant when the cluster constraints are also included in the analysis. The complementary nature of the data sets leads to a tight constraint on the mean matter density, {Omega}{sub m} and alleviates a number of other parameter degeneracies, including that between the scalar spectral index n{sub s}, the physical baryon density {Omega}{sub b}h{sup 2} and the optical depth {tau}. This complementary nature also allows us to examine models in which we drop the prior on the curvature. For non-flat models with a constant equation of state, we measure w{sub 0} = -1.09{sub -0.15}{sup +0.12} and obtain a tight constraint on the current dark energy density, {Omega}{sub de} = 0.70 {+-} 0.03. For dark energy models other than a cosmological constant, energy-momentum conservation requires the inclusion of spatial perturbations in the dark energy component. Our analysis includes such perturbations, assuming a sound speed c

  11. Tracking Galaxy Evolution Through Low-Frequency Radio ...

    Indian Academy of Sciences (India)

    Galaxies: active—galaxies: evolution—galaxies: individual: Speca—galaxies: individual: NGC ..... AGN-heated hot gas bubbles is nearly 1056 ergs and that is comparable to ener- getic impact of low-power ..... the probability may be, can create the central engines capable of launching massive energy feedback to the host ...

  12. Exploring the Evolution of Star Formation and Dwarf Galaxy Properties with JWST /MIRI Serendipitous Spectroscopic Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Bonato, Matteo; Sajina, Anna; McKinney, Jed; Marchesini, Danilo; Roebuck, Eric; Shipley, Heath [Department of Physics and Astronomy, Tufts University, 574 Boston Avenue, Medford, MA (United States); Zotti, Gianfranco De [INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Baronchelli, Ivano; Yan, Lin [California Institute of Technology, Pasadena, CA (United States); Negrello, Mattia [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Kurinsky, Noah [Department of Physics, Stanford University, Stanford, CA (United States); Pope, Alexandra [Department of Astronomy, University of Massachusetts Amherst, Amherst, MA (United States); Noriega-Crespo, Alberto [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD (United States); Kirkpatrick, Allison [Department of Astronomy, Yale University, New Haven, CT (United States)

    2017-02-20

    The James Webb Space Telescope ’s Medium Resolution Spectrometer (MRS), will offer nearly two orders of magnitude improvement in sensitivity and >3× improvement in spectral resolution over our previous space-based mid-IR spectrometer, the Spitzer IRS. In this paper, we make predictions for spectroscopic pointed observations and serendipitous detections with the MRS. Specifically, pointed observations of Herschel sources require only a few minutes on source integration for detections of several star-forming and active galactic nucleus lines, out to z = 3 and beyond. But the same data will also include tens of serendipitous 0 ≲ z ≲ 4 galaxies per field with infrared luminosities ranging ∼10{sup 6}–10{sup 13} L {sub ☉}. In particular, for the first time and for free we will be able to explore the L {sub IR} < 10{sup 9} L {sub ☉} regime out to z ∼ 3. We estimate that with ∼ 100 such fields, statistics of these detections will be sufficient to constrain the evolution of the low- L end of the infrared luminosity function, and hence the star formation rate function. The above conclusions hold for a wide range in the potential low- L end of the IR luminosity function, and account for the PAH deficit in low- L , low-metallicity galaxies.

  13. 3D Spectroscopic Surveys: Exploring Galaxy Evolution Mechanisms

    Science.gov (United States)

    Epinat, Benoît

    2011-12-01

    I review the major surveys of high redshift galaxies observed using integral field spectroscopy techniques in the visible and in the infrared. The comparison of various samples has to be done with care since they have different properties linked to their parent samples, their selection criteria and the methods used to study them. I present the various kinematic types of galaxies that are identified within these samples (rotators, mergers, etc.) and summarize the discussions on the mass assembly processes at various redshifts deduced from these classifications: at intermediate redshift (z ~ 0.6) merger may be the main mass assembly process whereas the role of cold gas accretion along cosmic web filaments may increase with redshift. The baryonic Tully-Fisher relation is also discussed. This relation seems to be already in place 3 Gyr after the Big-Bang and is then evolving until the present day. This evolution is interpreted as an increase of the stellar mass content of dark matter haloes of a given mass. The discovery of positive abundance gradients in MASSIV and LSD/AMAZE samples is highlighted. At z ~ 3 this discovery might be linked to cold gas accretion along cosmic filaments toward the centre whereas at lower redshift (z ~ 1.3), this may be mainly due to accretion of gas from outer reservoirs toward the centre via tidal tails due to interactions.

  14. A Chemical Evolution Model for the Fornax Dwarf Spheroidal Galaxy

    Directory of Open Access Journals (Sweden)

    Yuan Zhen

    2016-01-01

    Full Text Available Fornax is the brightest Milky Way (MW dwarf spheroidal galaxy and its star formation history (SFH has been derived from observations. We estimate the time evolution of its gas mass and net inflow and outflow rates from the SFH usinga simple star formation law that relates the star formation rate to the gas mass. We present a chemical evolution model on a 2D mass grid with supernovae (SNe as sources of metal enrichment. We find that a key parameter controlling the enrichment is the mass Mx of the gas to mix with the ejecta from each SN. The choice of Mx depends on the evolution of SN remnants and on the global gas dynamics. It differs between the two types of SNe involved and between the periods before and after Fornax became an MW satellite at time t = tsat. Our results indicate that due to the global gas outflow at t > tsat, part of the ejecta from each SN may directly escape from Fornax. Sample results from our model are presented and compared with data.

  15. Population dynamics constrain the cooperative evolution of cross-feeding.

    Directory of Open Access Journals (Sweden)

    James J Bull

    Full Text Available Cross-feeding is the exchange of nutrients among species of microbes. It has two potential evolutionary origins, one as an exchange of metabolic wastes or byproducts among species, the other as a form of cooperation known as reciprocal altruism. This paper explores the conditions favoring the origin of cooperative cross-feeding between two species. There is an extensive literature on the evolution of cooperation, and some of the requirements for the evolution of cooperative cross-feeding follow from this prior work-specifically the requirement that interactions be limited to small groups of individuals, such as colonies in a spatially structured environment. Evolution of cooperative cross-feeding by a species also requires that cross-feeding from the partner species already exists, so that the cooperating mutant will automatically be reciprocated for its actions. Beyond these considerations, some unintuitive dynamical constraints apply. In particular, the benefit of cooperative cross-feeding applies only in the range of intermediate cell densities. At low density, resource concentrations are too low to offset the cost of cooperation. At high density, resources shared by both species become limiting, and the two species become competitors. These considerations suggest that the evolution of cooperative cross-feeding in nature may be more challenging than for other types of cooperation. However, the principles identified here may enable the experimental evolution of cross-feeding, as born out by a recent study.

  16. Secular evolution of Milky Way-type galaxies

    Science.gov (United States)

    Combes, F.

    2017-12-01

    The internal evolution of disk galaxies like the Milky Way is driven by non-axisymmetries (bars) and the implied angular momentum transfer of the matter; baryons are essentially driven inwards to build a more concentrated disk. This mass concentration may lead to the decoupling of a secondary bar, since the orbit precessing frequency is then much enhanced. Vertical resonances with the bar will form a box/peanut bulge on a Gyr time-scale. Gas flows due to gravity torques can lead to a young nuclear disk forming stars, revealed by a σ-drop in velocity dispersion. These gas flows moderated by feedback produce intermittent accretion onto the super-massive black hole, and cycles of AGN activity. The fountain effect due to nuclear star formation may lead to inclined, and even polar nuclear disks.

  17. Star formation in bulgeless late-type galaxies: clues to their evolution

    Science.gov (United States)

    Das, M.; Sengupta, C.; Ramya, S.; Misra, K.

    2012-07-01

    We present Giant Meterwave Radio Telescope 1280-MHz radio continuum observations and follow-up optical studies of the disc and nuclear star formation in a sample of low-luminosity bulgeless galaxies. The main aim is to understand bulge formation and overall disc evolution in these late-type galaxies. We detected radio continuum from five of the 12 galaxies in our sample; the emission is mainly associated with disc star formation. Only two of the detected galaxies had extended radio emission; the others had patchy disc emission. In the former two galaxies, NGC 3445 and NGC 4027, the radio continuum is associated with star formation triggered by tidal interactions with nearby companion galaxies. We did follow-up Hα imaging and nuclear spectroscopy of both galaxies using the Himalayan Chandra Telescope. The Hα emission is mainly associated with the strong spiral arms. The nuclear spectra indicate ongoing nuclear star formation in NGC 3445 and NGC 4027 which may be associated with nuclear star clusters. No obvious signs of active galactic nuclei activity were detected. Although nearly bulgeless, both galaxies appear to have central oval distortions in the R-band images; these could represent pseudo-bulges that may later evolve into large bulges. We thus conclude that tidal interactions are an important means of bulge formation and disc evolution in bulgeless galaxies; without such triggers these galaxies appear to be low in star formation and overall disc evolution.

  18. Galaxy evolution in groups. NGC 3447/NGC 3447A: the odd couple in LGG 225

    Science.gov (United States)

    Mazzei, P.; Marino, A.; Rampazzo, R.; Plana, H.; Rosado, M.; Arias, L.

    2018-02-01

    Context. Local Group (LG) analogs (LGAs) are galaxy associations dominated by a few bright spirals reminiscent of the LG. The NGC 3447/NGC 3447A system is a member of the LGG 225 group, a nearby LGA. This system is considered a physical pair composed of an intermediate-luminosity late-type spiral, NGC 3447 itself, and an irregular companion, NGC 3447A, linked by a faint, short filament of matter. A ring-like structure in the NGC 3447 outskirts has been emphasised by Galaxy Evolution Explorer (GALEX) observations. Aims: This work aims to contribute to the study of galaxy evolution in low-density environments, a favourable habitat to highly effective encounters, shedding light on the evolution of the NGC 3447/NGC 3447A system. Methods: We performed a multi-λ analysis of the surface photometry of this system to derive its spectral energy distribution and structural properties using ultraviolet (UV), Swift UVOT, and optical Sloan Digital Sky Survey (SDSS) images complemented with available far-IR observations. We also characterised the velocity field of the pair using two-dimensional Hα kinematical observations of the system obtained with PUMA Fabry-Perot interferometer at the 2.1 m telescope of San Pedro Mártir (Mexico). All these data are used to constrain smooth particle hydrodynamic simulations with chemo-photometric implementation to shed light on the evolution of this system. Results: The luminosity profiles, from UV to optical wavelengths, are all consistent with the presence of a disc extending and including NGC 3447A. The overall velocity field does not emphasise any significant rotation pattern, rather a small velocity gradient between NGC 3447 and NGC 3447A. Our simulation, detached from a large grid explored to best-fit the global properties of the system, suggests that this arises from an encounter between two halos of equal mass. Conclusions: NGC 3447 and NGC 3447A belong to the same halo, NGC 3447A being a substructure of the same disk including NGC

  19. Protein Evolution along Phylogenetic Histories under Structurally Constrained Substitution Models

    Science.gov (United States)

    Arenas, Miguel; Dos Santos, Helena G.; Posada, David; Bastolla, Ugo

    2017-01-01

    Motivation Models of molecular evolution aim at describing the evolutionary processes at the molecular level. However, current models rarely incorporate information from protein structure. Conversely, structure-based models of protein evolution have not been commonly applied to simulate sequence evolution in a phylogenetic framework and they often ignore relevant evolutionary processes such as recombination. A simulation evolutionary framework that integrates substitution models that account for protein structure stability should be able to generate more realistic in silico evolved proteins for a variety of purposes. Results We developed a method to simulate protein evolution that combines models of protein folding stability, such that the fitness depends on the stability of the native state both with respect to unfolding and misfolding, with phylogenetic histories that can be either specified by the user or simulated with the coalescent under complex evolutionary scenarios including recombination, demographics and migration. We have implemented this framework in a computer program called ProteinEvolver. Remarkably, comparing these models with empirical amino acid replacement models, we found that the former produce amino acid distributions closer to distributions observed in real protein families, and proteins that are predicted to be more stable. Therefore, we conclude that evolutionary models that consider protein stability and realistic evolutionary histories constitute a better approximation of the real evolutionary process. Availability ProteinEvolver is written in C, can run in parallel, and is freely available from http://code.google.com/p/proteinevolver/. PMID:24037213

  20. Constraining dark energy and modified gravity with galaxy clusters, Oskar Klein Center for Cosmoparticle Physics, Stockholm, Sweden

    DEFF Research Database (Denmark)

    Rapetti Serra, David Angelo

    2011-01-01

    Using measurements of the abundance of galaxy clusters we obtain constraints on dark energy and gravity at cosmological scales. Our data set consists of 238 cluster detections drawn from the ROSAT All-Sky Survey and X-ray follow-up observations of 94 of those clusters. Using a new statistical...... framework we self-consistently and simultaneously constrain cosmology and observable-mass scaling relations accounting for survey biases, parameter covariances and systematic uncertainties. Allowing the linear growth index and the dark energy equation of state to take any constant values, we find...... no evidence for departures from GR+LCDM. If time permits, I will also present preliminary results on testing an alternative gravity model using our cluster data sets. Our results highlight the power of X-ray cluster studies to constrain cosmology...

  1. Cluster galaxy population evolution from the Subaru Hyper Suprime-Cam survey: brightest cluster galaxies, stellar mass distribution, and active galaxies

    Science.gov (United States)

    Lin, Yen-Ting; Hsieh, Bau-Ching; Lin, Sheng-Chieh; Oguri, Masamune; Chen, Kai-Feng; Tanaka, Masayuki; Chiu, I.-non; Huang, Song; Kodama, Tadayuki; Leauthaud, Alexie; More, Surhud; Nishizawa, Atsushi; Bundy, Kevin; Lin, Lihwai; Miyazaki, Satoshi; HSC Collaboration

    2018-01-01

    The unprecedented depth and area surveyed by the Subaru Strategic Program with the Hyper Suprime-Cam (HSC-SSP) have enabled us to construct and publish the largest distant cluster sample out to z~1 to date. In this exploratory study of cluster galaxy evolution from z=1 to z=0.3, we investigate the stellar mass assembly history of brightest cluster galaxies (BCGs), and evolution of stellar mass and luminosity distributions, stellar mass surface density profile, as well as the population of radio galaxies. Our analysis is the first high redshift application of the top N richest cluster selection, which is shown to allow us to trace the cluster galaxy evolution faithfully. Our stellar mass is derived from a machine-learning algorithm, which we show to be unbiased and accurate with respect to the COSMOS data. We find very mild stellar mass growth in BCGs, and no evidence for evolution in both the total stellar mass-cluster mass correlation and the shape of the stellar mass surface density profile. The clusters are found to contain more red galaxies compared to the expectations from the field, even after the differences in density between the two environments have been taken into account. We also present the first measurement of the radio luminosity distribution in clusters out to z~1.

  2. WITNESSING THE DIFFERENTIAL EVOLUTION OF DISK GALAXIES IN LUMINOSITY AND SIZE VIA GRAVITATIONAL LENSING

    Energy Technology Data Exchange (ETDEWEB)

    Bandara, Kaushala; Crampton, David; Peng, Chien; Simard, Luc [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

    2013-11-01

    We take advantage of the magnification in size and flux of a galaxy provided by gravitational lensing to analyze the properties of 62 strongly lensed galaxies from the Sloan Lens ACS (SLACS) Survey. The sample of lensed galaxies spans a redshift range of 0.20 ≤ z ≤ 1.20 with a median redshift of z = 0.61. We use the lens modeling code LENSFIT to derive the luminosities, sizes, and Sérsic indices of the lensed galaxies. The measured properties of the lensed galaxies show a primarily compact, {sup d}isk{sup -}like population with the peaks of the size and Sérsic index distributions corresponding to ∼1.50 kpc and n ∼ 1, respectively. Comparison of the SLACS galaxies to a non-lensing, broadband imaging survey shows that a lensing survey allows us to probe a galaxy population that reaches ∼2 mag fainter. Our analysis allows us to compare the (z) = 0.61 disk galaxy sample (n ≤ 2.5) to an unprecedented local galaxy sample of ∼670, 000 SDSS galaxies at z ∼ 0.1; this analysis indicates that the evolution of the luminosity-size relation since z ∼ 1 may not be fully explained by a pure-size or pure-luminosity evolution but may instead require a combination of both. Our observations are also in agreement with recent numerical simulations of disk galaxies that show evidence of a mass-dependent evolution since z ∼ 1, where high-mass disk galaxies (M{sub *} > 10{sup 9} M{sub ☉}) evolve more in size and low-mass disk galaxies (M{sub *} ≤ 10{sup 9} M{sub ☉}) evolve more in luminosity.

  3. Cecilia Payne-Gaposchkin Lecture: Galaxy Evolution over the Latter Half of Cosmic History

    Science.gov (United States)

    Faber, Sandra

    2004-05-01

    Several experiments are now gathering data in statistically valid numbers for intermediate-redshift galaxies out to z = 1 for the first time. The speaker will review results from DEEP2 and other surveys to sketch the current picture of the final stages of galaxy evolution. Galaxies are found to be divided into red and blue classes (ellipticals and spirals) as early as z = 1.2, but strong evolution seems to be occurring within each class. Morphologies of spiral-type precursors are highly irregular at z = 1, and the zero point and possibly the slope of the TF relation have changed. The total stellar mass in E/S0s has roughly doubled since that epoch. The processes whereby these events are occurring are not understood, and toy models for galaxy evolution do not fit the data. The key to understanding the Hubble sequence apparently lies in the properties of these galaxies at intermediate redshifts.

  4. The Effects of Environment on the Evolution of the Galaxy Stellar Mass Function

    Science.gov (United States)

    Papovich, Casey; Kawinwanichakij, Lalitwadee; Quadri, Ryan F.; Glazebrook, Karl; Labbé, Ivo; Tran, Kim-Vy H.; Forrest, Ben; Kacprzak, Glenn G.; Spitler, Lee R.; Straatman, Caroline M. S.; Tomczak, Adam R.

    2018-02-01

    We study the effects of galaxy environment on the evolution of the stellar mass function (SMF) over 0.2 Medium-Band Survey (NMBS) down to the stellar mass completeness limit, {log}{M}* /{M}ȯ > 9.0 (9.5) at z = 1.0 (2.0). We compare the SMFs for quiescent and star-forming galaxies in the highest and lowest environments using a density estimator based on the distance to the galaxies’ third-nearest neighbors. For star-forming galaxies, at all redshifts there are only minor differences with environment in the shape of the SMF. For quiescent galaxies, the SMF in the lowest densities shows no evolution with redshift other than an overall increase in number density (ϕ*) with time. This suggests that the stellar mass dependence of quenching in relatively isolated galaxies both is universal and does not evolve strongly. While at z≳ 1.5, the SMF of quiescent galaxies is indistinguishable in the highest and lowest densities, at lower redshifts, it shows a rapidly increasing number density of lower-mass galaxies, {log}{M}* /{M}ȯ ≃ 9{--}10, in the highest-density environments. We argue that this evolution can account for all the redshift evolution in the shape of the total quiescent galaxy SMF. This evolution in the quiescent galaxy SMF at higher redshift (z > 1) requires an environmental quenching efficiency that decreases with decreasing stellar mass at 0.5 environments. This requires a dominant environmental process such as starvation combined with rapid gas depletion and ejection at z > 0.5–1.0 for galaxies in our mass range. The efficiency of this process decreases with redshift, allowing other processes (such as galaxy interactions and ram-pressure stripping) to become more important at later times, z < 0.5.

  5. The Influence of the Environment on the Evolution of Galaxies

    Science.gov (United States)

    Sikkema, Geert

    2009-03-01

    In this thesis, we explore how the properties of galaxies depend on environment where they reside. The thesis consists of two parts, with each having its own data-set. Part 1 consists of observations done with a wide-field CCD-camera mounted on a middle-sized telescope. In Groningen, a software system ASTRO-WISE has been developed that will reduce observations the upcoming wide-field camera OmegaCAM. Our observations were used as a testbed for ASTRO-WISE. We looked at a region on the sky with a size of 16 full moons, which contains several galaxy clusters at a distance of about 1 billion lightyears. One type of galaxy, the so-called S0 galaxies, seem to have formed quite fast in the past few billion years in clusters. These type of galaxies probably evolve from spiral galaxies. Our observations give clues about how and where this transformation occurs. We find that the so-called red spirals might be a transition type of galaxy: between normal spirals and S0s. Furthermore, we find morphological differences between several types of galaxies in low and high density regions. Part 2 consists of Hubble Space Telescope dataof six relatively nearby shell galaxies. Shell galaxies are elliptical galaxies which deviations (shells) in their light distribution. We have determined very precisely the colours and shapes of shells as well as the presence of dust in these galaxies. The results imply that shells are the remains of small dwarf galaxies that have merged with the much larger elliptical galaxy. We also looked if the shell galaxies contain recently formed globular clusters. We find that two out of six of our shell galaxies show evidence for young globular clusters.

  6. The evolution of the metallicity gradient and the star formation efficiency in disc galaxies

    Science.gov (United States)

    Sillero, Emanuel; Tissera, Patricia B.; Lambas, Diego G.; Michel-Dansac, Leo

    2017-12-01

    We study the oxygen abundance profiles of the gas-phase components in hydrodynamical simulations of pre-prepared disc galaxies including major mergers, close encounters and isolated configurations. We analyse the evolution of the slope of oxygen abundance profiles and the specific star formation rate (sSFR) along their evolution. We find that galaxy-galaxy interactions could generate either positive or negative gas-phase oxygen profiles, depending on the state of evolution. Along the interaction, galaxies are found to have metallicity gradients and sSFR consistent with observations, on average. Strong gas inflows produced during galaxy-galaxy interactions or as a result of strong local instabilities in gas-rich discs are able to produce both a quick dilution of the central gas-phase metallicity and a sudden increase of the sSFR. Our simulations show that, during these events, a correlation between the metallicity gradients and the sSFR can be set up if strong gas inflows are triggered in the central regions in short time-scales. Simulated galaxies without experiencing strong disturbances evolve smoothly without modifying the metallicity gradients. Gas-rich systems show large dispersion along the correlation. The dispersion in the observed relation could be interpreted as produced by the combination of galaxies with different gas-richness and/or experiencing different types of interactions. Hence, our findings suggest that the observed relation might be the smoking gun of galaxies forming in a hierarchical clustering scenario.

  7. Constrained evolution of a bispecific enzyme: lessons for biocatalyst design.

    Science.gov (United States)

    Sugrue, E; Scott, C; Jackson, C J

    2017-01-25

    One of the central goals of protein design and engineering is to be able to accurately predict the effects of a mutation on stability and activity. However, the genetic context into which mutations are introduced can lead to complex interactions between the mutation and other amino acids and unpredictable, non-additive, effects. This phenomenon is known as intramolecular epistasis and has been shown to restrict evolutionary paths through laboratory directed evolution experiments and ancestral protein reconstruction, but has rarely been studied at a quantitative level in naturally evolving enzymes. Atrazine-specific and atrazine/ametryn bispecific triazine hydrolases (TrzN) have evolved in different bacterial strains over the past fifty years in response to the presence of the synthetic herbicides atrazine and ametryn. Here, we have investigated all 24 evolutionary trajectories that are possible from monofunctional to bispecific TrzN isoforms in terms of activity, stability, expression and structure. The results reveal that half of these trajectories are unviable due to inactive intermediates, with only 1/24 trajectories exhibiting consistent improvement in bispecificity. The most viable path requires the mutation of Gln241 to Glu241 first, which increases activity 3-fold with atrazine and 105-fold with ametryn, which is further optimised in subsequent evolutionary steps. The epistatic interactions between mutations, involving control of the pKa of catalytic residues, the thermostability of the protein, and soluble expression are shown to be responsible for the bottlenecks in this evolutionary landscape. This comprehensive analysis of the evolution of bispecificity highlights the importance of epistasis in protein engineering and evolution, which makes identifying the correct sequence in which to combine mutations extremely important.

  8. Observations and Models of Galaxy Assembly Bias

    Science.gov (United States)

    Campbell, Duncan A.

    2017-01-01

    The assembly history of dark matter haloes imparts various correlations between a halo’s physical properties and its large scale environment, i.e. assembly bias. It is common for models of the galaxy-halo connection to assume that galaxy properties are only a function of halo mass, implicitly ignoring how assembly bias may affect galaxies. Recently, programs to model and constrain the degree to which galaxy properties are influenced by assembly bias have been undertaken; however, the extent and character of galaxy assembly bias remains a mystery. Nevertheless, characterizing and modeling galaxy assembly bias is an important step in understanding galaxy evolution and limiting any systematic effects assembly bias may pose in cosmological measurements using galaxy surveys.I will present work on modeling and constraining the effect of assembly bias in two galaxy properties: stellar mass and star-formation rate. Conditional abundance matching allows for these galaxy properties to be tied to halo formation history to a variable degree, making studies of the relative strength of assembly bias possible. Galaxy-galaxy clustering and galactic conformity, the degree to which galaxy color is correlated between neighbors, are sensitive observational measures of galaxy assembly bias. I will show how these measurements can be used to constrain galaxy assembly bias and the peril of ignoring it.

  9. Giant Low Surface Brightness Galaxies: Evolution in Isolation M. Das

    Indian Academy of Sciences (India)

    Abstract. Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in ...

  10. Giant Low Surface Brightness Galaxies: Evolution in Isolation

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but ...

  11. The MUSE Hubble Ultra Deep Field Survey. IX. Evolution of galaxy merger fraction since z ≈ 6

    Science.gov (United States)

    Ventou, E.; Contini, T.; Bouché, N.; Epinat, B.; Brinchmann, J.; Bacon, R.; Inami, H.; Lam, D.; Drake, A.; Garel, T.; Michel-Dansac, L.; Pello, R.; Steinmetz, M.; Weilbacher, P. M.; Wisotzki, L.; Carollo, M.

    2017-11-01

    We provide, for the first time, robust observational constraints on the galaxy major merger fraction up to z ≈ 6 using spectroscopic close pair counts. Deep Multi Unit Spectroscopic Explorer (MUSE) observations in the Hubble Ultra Deep Field (HUDF) and Hubble Deep Field South (HDF-S) are used to identify 113 secure close pairs of galaxies among a parent sample of 1801 galaxies spread over a large redshift range (0.2 SED) fitting over the extensive UV-to-NIR HST photometry available in these deep Hubble fields, adding Spitzer IRAC bands to better constrain masses for high-redshift (z ⩾ 3) galaxies. These stellar masses are used to isolate a sample of 54 major close pairs with a galaxy mass ratio limit of 1:6. Among this sample, 23 pairs are identified at high redshift (z ⩾ 3) through their Lyα emission. The sample of major close pairs is divided into five redshift intervals in order to probe the evolution of the merger fraction with cosmic time. Our estimates are in very good agreement with previous close pair counts with a constant increase of the merger fraction up to z ≈ 3 where it reaches a maximum of 20%. At higher redshift, we show that the fraction slowly decreases down to about 10% at z ≈ 6. The sample is further divided into two ranges of stellar masses using either a constant separation limit of 109.5 M⊙ or the median value of stellar mass computed in each redshift bin. Overall, the major close pair fraction for low-mass and massive galaxies follows the same trend. These new, homogeneous, and robust estimates of the major merger fraction since z ≈ 6 are in good agreement with recent predictions of cosmological numerical simulations. Based on observations made with ESO telescopes at the La Silla-Paranal Observatory under programmes 094.A-0289(B), 095.A-0010(A), 096.A-0045(A) and 096.A-0045(B).

  12. Evolution of the Galaxy and the Birth of the Solar System: The Short ...

    Indian Academy of Sciences (India)

    An attempt is made, probably for the first time, to understand the origin of the solar system in context with the evolution of the galaxy as a natural consequence of the birth of several generations of stellar clusters. The galaxy is numerically simulated to deduce the inventories of the short-lived nuclides, 26Al, 36Cl, 41Ca, 53Mn ...

  13. New Deep HST/ACS Photometry of NGC 1569: Constraining the Evolution of the Strongest Starburst in the Nearby Universe

    Science.gov (United States)

    Grocholski, Aaron J.; van der Marel, R. P.; Aloisi, A.; Mack, J.

    2010-01-01

    Massive starbursts drive the evolution of galaxies at high redshift, but they can only be studied in detail in the nearby Universe where they are much rarer. The dwarf irregular galaxy NGC 1569 has always been considered the closest example of a true starburst, with exceptionally high sustained star formation (SF) over the last Gyr. This recent SF has been extensively constrainted by HST studies that reached to near the presumed magnitude of the tip of the red giant branch (TRGB). These studies could not address the onset of the most ancient SF or the triggering mechanism of the current starburst. Here we present new deep HST ACS/WFC photometry of the resolved stars in NGC 1569 that goes some 4 mag deeper than any previous HST observations. These data allowed us to unequivocally detect and measure the TRGB for the first time and show that NGC 1569 is considerably farther away than previously believed. At ˜3 Mpc it is actually a member of the IC 342 group of galaxies, instead of being a starburst in isolation. In addition to the TRGB, our increased photometric depth also gives access to the fainter red clump and horizontal branch features in the I vs V-I color-magnitude diagram (CMD) of NGC 1569, allowing us to constrain for the first time even the most ancient SFH of this extreme starburst through the use of synthetic CMDs. The area sampled by our ACS/WFC observations is some 25 times larger than in previous HST studies, allowing us to characterize the spatial variations of the SFH, from the central star forming regions of NGC 1569 out into the older and more sparsely populated "halo". The results reveal the evolutionary status of this extreme starburst over cosmic time.

  14. Discovering structure and evolution within the coronae of Seyfert galaxies

    Science.gov (United States)

    Wilkins, Daniel; Gallo, Luigi C.; Silva, Catia; Costantini, Elisa

    2017-08-01

    Detailed analysis of the reflection and reverberation of X-rays from the innermost regions of AGN accretion discs reveals the structure and processes that produce the intense continuum emission and the extreme variability we see, right down to the innermost stable orbit and event horizon of the black hole. Observations of Seyfert galaxies spanning more than a decade have enabled measurement of the geometry of the corona and how it evolves, leading to orders of magnitude in variability. They reveal processes the corona undergoes during transient events, notably the collimation and ejection of the corona during X-ray flares, reminiscent of the aborted launching of a jet.Recent reverberation studies, of the Seyfert galaxy I Zwicky 1 with XMM-Newton, are revealing structures within the corona for the very first time. A persistent collimated core is discovered, akin to the base of a jet embedded in the innermost regions alongside an extended corona related to the accretion disc. The detection of the flare in the X-ray emission enables the evolution of both the collimated and extended portions of the corona to be tracked. The flare is seen originating as an increase in activity above the accretion disc before propagating inwards, energising the collimated core at a later time, leading to a second sharp increase in the X-ray luminosity.This gives us important constraints on the processes by which energy is liberated from black hole accretion flows, how they are governed over time and how jets are launched, giving us the deepest insight to date of how these extreme objects are powered.

  15. The cosmological x-ray evolution of stars, AGN, and galaxies

    Science.gov (United States)

    Watson, Casey R.

    It is of great importance for our understanding of galaxy evolution to determine whether there is a break or a continuum in these processes from the powerful quasars and starbursts of the past, to the seemingly dormant, "normal" galaxies more typical of the present epoch. To help settle the question, we combined optical data from the NOAO Deep Wide-Field Survey (NDWFS), X-ray data from the XBootes survey, and spectral information from the AGN and Galaxy Evolution Survey (AGES) in order to simultaneously obtain deep and wide coverage of the normal galaxy population. In this manner, my collaborators and I were able to bridge the gap in normal galaxy X-ray coverage between large- area local surveys and high redshift, small volume deep fields. In particular, I present the X-ray evolution of normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored redshift range 0 [Special characters omitted.] z [Special characters omitted.] 0.5. We use radial emission profiles of low redshift galaxies, hardness ratios, and X-ray to optical luminosity ratios to estimate the relative contributions of stellar and nuclear sources. These tests suggest that the X-ray emission from spectroscopically late-type galaxies is dominated by star formation, while that from early-type galaxies is dominated by AGN. To extend our analysis of AGN to higher redshifts, we investigated the X-ray luminosity evolution of 3316 red galaxies selected over a wide range in redshift (0.3 global decline in accretion onto the central, supermassive black holes of early-type galaxies has proceeded in a similar manner at both the faint and the bright (individually detectable) ends of the AGN luminosity function. (Abstract shortened by UMI.)

  16. Composite Differential Evolution with Modified Oracle Penalty Method for Constrained Optimization Problems

    OpenAIRE

    Minggang Dong; Ning Wang; Xiaohui Cheng; Chuanxian Jiang

    2014-01-01

    Motivated by recent advancements in differential evolution and constraints handling methods, this paper presents a novel modified oracle penalty function-based composite differential evolution (MOCoDE) for constrained optimization problems (COPs). More specifically, the original oracle penalty function approach is modified so as to satisfy the optimization criterion of COPs; then the modified oracle penalty function is incorporated in composite DE. Furthermore, in order to solve more complex ...

  17. The Horizon-AGN simulation: evolution of galaxy properties over cosmic time

    Science.gov (United States)

    Kaviraj, S.; Laigle, C.; Kimm, T.; Devriendt, J. E. G.; Dubois, Y.; Pichon, C.; Slyz, A.; Chisari, E.; Peirani, S.

    2017-06-01

    We compare the predictions of Horizon-AGN, a hydrodynamical cosmological simulation that uses an adaptive mesh refinement code, to observational data in the redshift range 0 age. By comparison to Horizon-noAGN, a twin simulation without active galactic nuclei feedback, we quantify how feedback from black holes is likely to help shape galaxy stellar-mass growth in the redshift range 0 successfully captures the evolutionary trends of observed galaxies over the lifetime of the Universe, making it an excellent tool for studying the processes that drive galaxy evolution and making predictions for the next generation of galaxy surveys.

  18. Constraining omega from X-ray properties of clusters of galaxies at high redshifts

    DEFF Research Database (Denmark)

    Sadat, R.; Blanchard, A.; Oukbir, J.

    1997-01-01

    Properties of high redshift clusters are a fundamental source of information for cosmology. It has been shown by Oukbir and Blanchard (1997) that the combined knowledge of the redshift distribution of X-ray clusters of galaxies and the luminosity-temperature correlation, L-X - T-X, provides a pow...

  19. Is There any Evidence of Evolution in the Color Distribution of Galaxies from J = 13 TO J = 24 Magnitude?

    Science.gov (United States)

    Bruzual, G.

    1987-05-01

    ABSTRACT. The available distributions of galaxy colors from J = 13 to J = 24 magnitude are studied and interpreted in terms of populations of both evolving and non-evolving normal galaxies of different morphological classes, distributed in magnitude in the co-moving volume according to the Schechter Luminosity Function. Different cosmological models are explored and constraints are set on the amount of spectral evolution present in the galaxy samples. Key WOJtct : GALAXIES-EVOLUTION

  20. The evolution of the oxygen abundance radial gradient in the Milky Way Galaxy disk

    Science.gov (United States)

    Mollá, Mercedes; Cavichia, Oscar; Costa, Roberto D. D.; Maciel, Walter J.; Gibson, Brad; Díaz, Angeles I.

    2017-10-01

    We review the state of our chemical evolution models for spiral and low mass galaxies. We analyze the consequences of using different stellar yields, infall rate laws and star formation prescriptions in the time/redshift evolution of the radial distributions of abundances, and other quantities as star formation rate or gas densities, in the Milky Way Galaxy; In particular we will study the evolution of the oxygen abundance radial gradient analyzing its relation with the ratio SFR/infall. We also compare the results with our old chemical evolution models, cosmological simulations and with the existing data, mainly with the planetary nebulae abundances.

  1. Sharing Gravity's Microscope: Star Formation and Galaxy Evolution for Underserved Arizonans

    Science.gov (United States)

    Knierman, Karen A.; Monkiewicz, Jacqueline A.; Bowman, Catherine DD; Taylor, Wendy

    2016-01-01

    Learning science in a community is important for children of all levels and especially for many underserved populations. This project combines HST research of galaxy evolution using gravitationally lensed galaxies with hands-on activities and the Starlab portable planetarium to link astronomy with families, teachers, and students. To explore galaxy evolution, new activities were developed and evaluated using novel evaluation techniques. A new set of galaxy classification cards enable inquiry-based learning about galaxy ages, evolution, and gravitational lensing. Activities using new cylinder overlays for the Starlab transparent cylinder will enable the detailed examination of star formation and galaxy evolution as seen from the viewpoint inside of different types of galaxies. These activities were presented in several Arizona venues that enable family and student participation including ASU Earth and Space Open House, Arizona Museum of Natural History Homeschooling Events, on the Salt River Pima-Maricopa Indian Community, and inner city Phoenix schools serving mainly Hispanic populations. Additional events targeted underserved families at the Phoenix Zoo, in Navajo County, and for the Pascua Yaqui Tribe. After evaluation, the activities and materials will also be shared with local teachers and nationally.

  2. Extragalactic Thick Disks: Implications for Early Galaxy Evolution

    OpenAIRE

    Dalcanton, Julianne J.; Seth, Anil; Yoachim, Peter

    2005-01-01

    I briefly review the growing evidence that thick stellar disks surround most edge-on disk galaxies. Recent studies show that these extragalactic thick disks have old ages, low metallicities, long scale lengths, and moderately flattened axial ratios, much like the thick disk of the Milky Way. However, the properties of thick disks change systematically with the mass of the galaxy. The thick disks of low mass galaxies are more prominent and somewhat more metal-poor than those surrounding massiv...

  3. STAR-FORMING GALAXY EVOLUTION IN NEARBY RICH CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Tyler, K. D.; Rieke, G. H. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Bai, L. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street Room 101, Toronto, Ontario M5S 3H4 (Canada)

    2013-08-20

    Dense environments are known to quench star formation in galaxies, but it is still unknown what mechanism(s) are directly responsible. In this paper, we study the star formation of galaxies in A2029 and compare it to that of Coma, combining indicators at 24 {mu}m, H{alpha}, and UV down to rates of 0.03 M{sub Sun} yr{sup -1}. We show that A2029's star-forming galaxies follow the same mass-SFR relation as the field. The Coma cluster, on the other hand, has a population of galaxies with star formation rates (SFRs) significantly lower than the field mass-SFR relation, indicative of galaxies in the process of being quenched. Over half of these galaxies also host active galactic nuclei. Ram-pressure stripping and starvation/strangulation are the most likely mechanisms for suppressing the star formation in these galaxies, but we are unable to disentangle which is dominating. The differences we see between the two clusters' populations of star-forming galaxies may be related to their accretion histories, with A2029 having accreted its star-forming galaxies more recently than Coma. Additionally, many early-type galaxies in A2029 are detected at 24 {mu}m and/or in the far-UV, but this emission is not directly related to star formation. Similar galaxies have probably been classified as star forming in previous studies of dense clusters, possibly obscuring some of the effects of the cluster environment on true star-forming galaxies.

  4. Galaxy Evolution in the Cluster Abell 85: New Insights from the Dwarf Population

    Science.gov (United States)

    Habas, Rebecca; Fadda, Dario; Marleau, Francine R.; Biviano, Andrea; Durret, Florence

    2018-01-01

    We present the first results of a new spectroscopic survey of the cluster Abell 85 targeting 1466 candidate cluster members within the central ˜1 deg2 of the cluster and having magnitudes mr cluster members or part of an infalling population. A significant fraction are low mass; the median stellar mass of the sample is 109.6 M⊙, and 25% have stellar masses below 109 M⊙ (i.e. 133 dwarf galaxies). We also identify seven active galactic nuclei (AGN), four of which reside in dwarf host galaxies. We probe the evolution of star formation rates, based on Hα emission and continuum modeling, as a function of both mass and environment. We find that more star forming galaxies are observed at larger clustercentric distances, while infalling galaxies show evidence for recently enhanced star forming activity. Main sequence galaxies, defined by their continuum star formation rates, show different evolutionary behavior based on their mass. At the low mass end, the galaxies have had their star formation recently quenched, while more massive galaxies show no significant change. The timescales probed here favor fast quenching mechanisms, such as ram-pressure stripping. Galaxies within the green valley, defined similarly, do not show evidence of quenching. Instead, the low mass galaxies maintain their levels of star forming activity, while the more massive galaxies have experienced a recent burst.

  5. The evolution of the cluster optical galaxy luminosity function between z = 0.4 and 0.9 in the DAFT/FADA survey

    Science.gov (United States)

    Martinet, Nicolas; Durret, Florence; Guennou, Loïc; Adami, Christophe; Biviano, Andrea; Ulmer, Melville P.; Clowe, Douglas; Halliday, Claire; Ilbert, Olivier; Márquez, Isabel; Schirmer, Mischa

    2015-03-01

    Context. There is some disagreement about the abundance of faint galaxies in high-redshift clusters, with contradictory results in the literature arising from studies of the optical galaxy luminosity function (GLF) for small cluster samples. Aims: We compute GLFs for one of the largest medium-to-high-redshift (0.4 ≤ z DAFT/FADA survey in the B,V,R, and I rest-frame bands. We used photometric redshifts computed from BVRIZJ images to constrain galaxy cluster membership. We carried out a detailed estimate of the completeness of our data. We distinguished the red-sequence and blue galaxies using a V - I versus I colour-magnitude diagram. We studied the evolution of these two populations with redshift. We fitted Schechter functions to our stacked GLFs to determine average cluster characteristics. Results: We find that the shapes of our GLFs are similar for the B,V,R, and I bands with a drop at the red GLF faint ends that is more pronounced at high redshift: αred ~ -0.5 at 0.40 ≤ z 0.1 at 0.65 ≤ z < 0.90. The blue GLFs have a steeper faint end (αblue ~ -1.6) than the red GLFs, which appears to be independent of redshift. For the full cluster sample, blue and red GLFs meet at MV = -20, MR = -20.5, and MI = -20.3. A study of how galaxy types evolve with redshift shows that late-type galaxies appear to become early types between z ~ 0.9 and today. Finally, the faint ends of the red GLFs of more massive clusters appear to be richer than less massive clusters, which is more typical of the lower redshift behaviour. Conclusions: Our results indicate that these clusters form at redshifts higher than z = 0.9 from galaxy structures that already have an established red sequence. Late-type galaxies then appear to evolve into early types, enriching the red sequence between this redshift and today. This effect is consistent with the evolution of the faint-end slope of the red sequence and the galaxy type evolution that we find. Finally, faint galaxies accreted from the field

  6. The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune [Univ. of Tokyo (Japan); et al.

    2012-05-01

    We present a statistical analysis of the final lens sample from the Sloan Digital Sky Survey Quasar Lens Search (SQLS). The number distribution of a complete subsample of 19 lensed quasars selected from 50,836 source quasars is compared with theoretical expectations, with particular attention to the selection function. Assuming that the velocity function of galaxies does not evolve with redshift, the SQLS sample constrains the cosmological constant to \\Omega_\\Lambda=0.79^{+0.06}_{-0.07}(stat.)^{+0.06}_{-0.06}(syst.) for a flat universe. The dark energy equation of state is found to be consistent with w=-1 when the SQLS is combined with constraints from baryon acoustic oscillation (BAO) measurements or results from the Wilkinson Microwave Anisotropy Probe (WMAP). We also obtain simultaneous constraints on cosmological parameters and redshift evolution of the galaxy velocity function, finding no evidence for redshift evolution at z<1 in any combinations of constraints. For instance, number density evolution quantified as \

  7. The Evolution of Neutral Hydrogen in Galaxy Groups

    Science.gov (United States)

    Sanderson, Kelly Nicole; Wilcots, Eric; Hess, Kelley M.

    2018-01-01

    The Illustris suite of simulations is held as the standard of large scale gravitational and hydro-dynamical simulations and allows us to make a better comparisons with physical processes at the gaseous level by providing a higher mass resolution than previously available through the Millenium-II simulation. We present a comparison of an analysis on the HI content and distribution of galaxies in groups as a function of their group dark matter halo to the results of a large scale cosmological simulation. From the simulation we select optical group members above a Mr=-18 r-band magnitude and HI group members with HI above 109.5M⊙. We find that 74% of the HI detected galaxies are in groups or clusters and 84% of the optically detected galaxies are in groups or clusters. In the Hess & Wilcots (2013) paper it was found that as group membership, or group dark matter halo mass, increased, the fraction of galaxies detected in HI decreased and the spatial distribution of galaxies in these groups increased. We show the spatial distributions of galaxies, HI and optically detected, in order to reproduce these results. We find that Illustris qualitatively reproduces these trends, however, the simulation seems to be overestimating the mass of HI gas in all of its galaxies as well as the number of galaxies above the 109.5M⊙ limit.

  8. Modeling the Evolution of Galaxy Properties across Cosmic Time with Numerical Simulations

    Science.gov (United States)

    Torrey, Paul A.

    We present a series of numerical galaxy formation studies which apply new numerical methods to produce increasingly realistic galaxy formation models. We first investigate the metallicity evolution of a large set of idealized hydrodynamical galaxy merger simulations of colliding galaxies. We find that inflows of metal-poor interstellar gas triggered by galaxy tidal interactions can account for the systematically lower central oxygen abundances observed in local interacting galaxies. We show the central metallicity evolution during merger events is determined by a competition between the inflow of low-metallicity gas and enrichment from star formation. We find a time-averaged depression in the galactic nuclear metallicity of ~0.07 dex for gas-poor disk-disk interactions, which explains the observed close pair mass-metallicity and separation-metallicity relationships. We then pioneer the impact of a novel hydro solver in our understanding of galaxy gas disk assembly by comparing the structural properties of galaxies formed in cosmological simulations using the smoothed particle hydrodynamics (SPH) code GADGET with those using the moving-mesh code AREPO. We find that the cold gas disks formed using the moving mesh approach have systematically larger disk scale lengths and higher specific angular momenta than their GADGET counterparts across a wide range in halo masses. We articulate the numerical origins of these differences, and discuss the impact on large body of galaxy formation literature. We explore the performance of a recently implemented feedback model in AREPO which includes primordial and metal line radiative cooling with self-shielding corrections; stellar evolution with associated mass loss and chemical enrichment; feedback by stellar winds; black hole seeding, growth and merging; and AGN quasar- and radio-mode heating with a phenomenological prescription for AGN electro-magnetic feedback. We demonstrate that our feedback scheme is capable of producing

  9. Galaxy evolution. Isolated compact elliptical galaxies: stellar systems that ran away.

    Science.gov (United States)

    Chilingarian, Igor; Zolotukhin, Ivan

    2015-04-24

    Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts. Copyright © 2015, American Association for the Advancement of Science.

  10. A Model for Gas Dynamics and Chemical Evolution of the Fornax Dwarf Spheroidal Galaxy

    Science.gov (United States)

    Yuan, Zhen

    We present an empirical model for the halo evolution, global gas dynamics and chemical evolution of Fornax, the brightest Milky Way (MW) dwarf spheroidal galaxy (dSph). Assuming a global star formation rate psi(t) = lambda*(t)[Mg( t)/M[solar masses

  11. Composite Differential Evolution with Modified Oracle Penalty Method for Constrained Optimization Problems

    Directory of Open Access Journals (Sweden)

    Minggang Dong

    2014-01-01

    Full Text Available Motivated by recent advancements in differential evolution and constraints handling methods, this paper presents a novel modified oracle penalty function-based composite differential evolution (MOCoDE for constrained optimization problems (COPs. More specifically, the original oracle penalty function approach is modified so as to satisfy the optimization criterion of COPs; then the modified oracle penalty function is incorporated in composite DE. Furthermore, in order to solve more complex COPs with discrete, integer, or binary variables, a discrete variable handling technique is introduced into MOCoDE to solve complex COPs with mix variables. This method is assessed on eleven constrained optimization benchmark functions and seven well-studied engineering problems in real life. Experimental results demonstrate that MOCoDE achieves competitive performance with respect to some other state-of-the-art approaches in constrained optimization evolutionary algorithms. Moreover, the strengths of the proposed method include few parameters and its ease of implementation, rendering it applicable to real life. Therefore, MOCoDE can be an efficient alternative to solving constrained optimization problems.

  12. Can Planck constrain indirect detection of dark matter in our galaxy?

    OpenAIRE

    Delahaye, Timur; Bœhm, Céline; Silk, Joseph

    2011-01-01

    We investigate the synchrotron emission (both intensity and morphology) associated with generic dark matter particles and make predictions for the PLANCK experiment using the FERMI data and a model for the astrophysical sources. Our results indicate that the morphology of the dark matter plus astrophysical source synchrotron emission is frequency-dependent. We show that a thorough comparison between LFI and HFI data can potentially provide a new tool for constraining the dark matter particle ...

  13. The role of major mergers in (obscured) black hole growth and galaxy evolution

    Science.gov (United States)

    Treister, E.; Privon, G.; Ricci, C.; Bauer, F.; Schawinski, K.; MODA Collaboration

    2017-10-01

    A clear picture is emerging in which rapid supermassive black hole (SMBH) growth episodes (luminous AGN) are directly linked to major galaxy mergers. Here, we present the first results from our MODA program aimed to obtain optical and near-IR Integral Field Unit (IFU) spectroscopy and mm/sub-mm ALMA maps for a sample of confirmed nearby dual AGN (separation 10 kpc), including the archetypical galaxy NGC6240. Specifically, we will focus here on Mrk 463, a very rich system of two galaxies separated by 3.8 kpc hosting two SMBH growing simultaneously. Clear evidence for complex morphologies and kinematics, outflows and feedback effects can be seen in this system, evidencing the deep connection between major galaxy mergers, SMBH growth and galaxy evolution.

  14. Galaxy evolution in merging clusters: The passive core of the "Train Wreck" cluster of galaxies, A 520

    Science.gov (United States)

    Deshev, Boris; Finoguenov, Alexis; Verdugo, Miguel; Ziegler, Bodo; Park, Changbom; Hwang, Ho Seong; Haines, Christopher; Kamphuis, Peter; Tamm, Antti; Einasto, Maret; Hwang, Narae; Park, Byeong-Gon

    2017-11-01

    Aims: The mergers of galaxy clusters are the most energetic events in the Universe after the Big Bang. With the increased availability of multi-object spectroscopy and X-ray data, an ever increasing fraction of local clusters are recognised as exhibiting signs of recent or past merging events on various scales. Our goal is to probe how these mergers affect the evolution and content of their member galaxies. We specifically aim to answer the following questions: is the quenching of star formation in merging clusters enhanced when compared with relaxed clusters? Is the quenching preceded by a (short-lived) burst of star formation? Methods: We obtained optical spectroscopy of >400 galaxies in the field of the merging cluster Abell 520. We combine these observations with archival data to obtain a comprehensive picture of the state of star formation in the members of this merging cluster. Finally, we compare these observations with a control sample of ten non-merging clusters at the same redshift from The Arizona Cluster Redshift Survey (ACReS). We split the member galaxies into passive, star forming or recently quenched depending on their spectra. Results: The core of the merger shows a decreased fraction of star forming galaxies compared to clusters in the non-merging sample. This region, dominated by passive galaxies, is extended along the axis of the merger. We find evidence of rapid quenching of the galaxies during the core passage with no signs of a star burst on the time scales of the merger (≲0.4 Gyr). Additionally, we report the tentative discovery of an infalling group along the main filament feeding the merger, currently at 2.5 Mpc from the merger centre. This group contains a high fraction of star forming galaxies as well as approximately two thirds of all the recently quenched galaxies in our survey. The reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  15. Evolution of Consumption Volatility for the Liquidity Constrained Households over 1983 to 2004

    OpenAIRE

    Gorbachev, Olga; Dogra, Keshav

    2009-01-01

    We study whether the increased income uncertainty in the US over the last quarter-century had a negative impact on household welfare by looking at variability of household consumption growth. We are particularly interested in understanding the effect of greater uncertainty on the liquidity constrained households. We study the evolution of liquidity constraints in the US in thePanel Study of Income Dynamics, greatly extending Jappelli et al. [1998] methodology on how to construct such measures...

  16. Angular Momentum Evolution Of Disk Galaxies At High Redshift

    Science.gov (United States)

    Okamura, Taku; Kazuhiro, Shimasaku; Ryota, Kawamata

    2017-06-01

    The stellar disk size of a galaxy depends on the fraction of the dark-halo mass settled as disk stars, m★= M★/Mdh, and the fraction of the dark-halo angular momentum transferred to the disk, j★ = J★/Jdh. Since j★ is also determined by various star-formation related mechanisms such as inflows and feedbacks, measuring j★ and m★ at high redshifts is needed to understand the formation history of disk galaxies. We use the 3D-HST GOODS-S, COSMOS, and AEGIS imaging data and photo-z catalogs to examine j★ and m★ for star-forming galaxies at z 2,3,4, when disks are actively forming. We find that the j★/m★ ratio is roughly constant at ≃ 0.8 for all three redshifts over the entire halo mass range examined. This high ratio is close to those of local disk galaxies but a factor of a few higher than predicted (at z 2) by galaxy formation models. We also find that a significant fraction of our galaxies appear to be unstable against bar formation.

  17. The evolution of galaxy metallicity scaling relations in cosmological hydrodynamical simulations

    Science.gov (United States)

    De Rossi, M. E.; Theuns, T.; Font, A. S.; McCarthy, I. G.

    2015-09-01

    The evolution of the metal content of galaxies and its relations to other global properties [such as total stellar mass (M*), circular velocity, star formation rate (SFR), halo mass, etc.] provides important constraints on models of galaxy formation. Here we examine the evolution of metallicity scaling relations of simulated galaxies in the Galaxies-Intergalactic Medium Interaction Calculation suite of cosmological simulations. We make comparisons to observations of the correlation of gas-phase abundances with M* (the mass-metallicity relation, MZR), as well as with both M* and SFR or gas mass fraction (the so-called 3D fundamental metallicity relations, FMRs). The simulated galaxies follow the observed local MZR and FMRs over an order of magnitude in M*, but overpredict the metallicity of massive galaxies (log M* ≳ 10.5), plausibly due to inefficient feedback in this regime. We discuss the origin of the MZR and FMRs in the context of galactic outflows and gas accretion. We examine the evolution of MZRs defined using different elements that probe the three enrichment channels [SNII, SNIa, and asymptotic giant branch (AGB) stars]. Relations based on elements produced mainly by SNII evolve weakly, whereas those based on elements produced preferentially in SNIa/AGB exhibit stronger evolution, due to the longer time-scales associated with these channels. Finally, we compare the relations of central and satellite galaxies, finding systematically higher metallicities for satellites, as observed. We show that this is due to the removal of the metal-poor gas reservoir that normally surrounds galaxies and acts to dilute their gas-phase metallicity (via cooling/accretion on to the disc), but is lost due to ram-pressure stripping for satellites.

  18. HI-Selected Galaxies in Hierarchical Models of Galaxy Formation and Evolution

    Science.gov (United States)

    Zoldan, Anna

    2017-07-01

    This poster presents the main results of a statistical study of HI-selected galaxies based on six different semi-analytic models, all run on the same cosmological N-body simulation. One of these models includes an explicit treatment for the partition of cold gas into atomic and molecular hydrogen. All models considered agree nicely with the measured HI mass function in the local Universe and with the measured scaling relations between HI and galaxy stellar mass. Most models also reproduce the observed 2-point correlation function for HI rich galaxies, with the exception of one model that predicts very little HI associated with galaxies in haloes above 10^12 Msun. We investigated the influence of satellite treatment on the final HI content and found that it introduces large uncertainties at low HI masses. We found that the assumption of instantaneous stripping of hot gas in satellites does not translate necessarily in lower HI masses. We demonstrate that the assumed stellar feedback, combined with star formation, also affect significantly the gas content of satellite galaxies. Finally, we also analyse the origin of the correlation between HI content of model galaxies and the spin of the parent haloes. Zoldan et al., 2016, MNRAS, 465, 2236

  19. Probing Galaxy Formation and Evolution with Space Born Sub-Millimeter Telescopes

    Science.gov (United States)

    Dwek, Eli; Arendt, Richard G.; Moseley, Harvey; Benford, Dominic; Shafer, Richard; Mather, John; Oegerle, William (Technical Monitor)

    2002-01-01

    A major unresolved question in cosmology is how the complex system of galaxies we see in the present universe evolved from an almost perfectly smooth beginning. Multiwavelength observations of galaxies have revealed that a significant fraction of their UV-visible starlight is absorbed and reradiated by dust at infrared JR) and submillimeter wavelengths. The cumulative IR-submm. emission from galaxies since the epoch of recombination, the cosmic IR background, has recently been recorded by the COBE satellite. The COBE observations in combination with recent submm surveys conducted with the SCUBA on the 15 m JCMT have shown that most of the radiation from star formation that has taken place in the early stages of galaxy evolution is reradiated by dust at submm wavelengths. Therefore, submm telescopes offer a unique probe of the early stages of galaxy formation and evolution. This talk will: (1) consider the impact of telescope diameter on the depth of the survey (what redshift can be probed) at different wavelengths; (2) discuss the relative scientific merits of high-resolution narrow-field surveys versus lower resolution deep surveys; and (3) show how both strategies offer complementary information crucial to our understanding of the structure and evolution of galaxies in the universe.

  20. Constraining cosmology with the velocity function of low-mass galaxies

    Science.gov (United States)

    Schneider, Aurel; Trujillo-Gomez, Sebastian

    2018-01-01

    The number density of field galaxies per rotation velocity, referred to as the velocity function, is an intriguing statistical measure probing the smallest scales of structure formation. In this paper we point out that the velocity function is sensitive to small shifts in key cosmological parameters such as the amplitude of primordial perturbations (σ8) or the total matter density (Ωm). Using current data and applying conservative assumptions about baryonic effects, we show that the observed velocity function of the Local Volume favours cosmologies in tension with the measurements from Planck but in agreement with the latest findings from weak lensing surveys. While the current systematics regarding the relation between observed and true rotation velocities are potentially important, upcoming data from HI surveys as well as new insights from hydrodynamical simulations will dramatically improve the situation in the near future.

  1. The Effects of Cluster Environment on the Chemical Evolution of Galaxies

    Science.gov (United States)

    Pilyugin, L. S.; Ferrini, F.

    The values of oxygen deficiency have been derived for nine Virgo cluster spiral galaxies from the sample of Skillman et al (1996) which ranges from HI deficient spirals (three galaxies near the center of cluster) to spirals with normal HI contents (three galaxies at the periphery of cluster). The chemical properties of Virgo cluster spiral galaxies have been compared with chemical properties of field spiral galaxies considered by Pilyugin and Ferrini (1998). It has been found that the sample of spirals at the periphery of the cluster is a mixture of objects without, with moderate, and with significant oxygen abundance deficiency. It confirms the conclusion of Skillman et al (1996) that spirals at the periphery of the cluster are indistinguishable from field galaxies. All the spirals near the center of the cluster, within the limited sample here considered, have no oxygen deficiency, and are more advanced in evolution than spirals at the periphery of the cluster or than field spirals. These facts can be considered as a hint that, in the case of spiral galaxies near the center of a cluster, the cluster environment inhibits gas exchange between the galaxy and its surroundings at the present epoch and can slightly enhance the efficiency of star formation. The positions of Virgo spirals without oxygen abundance deficiency in the gas mass fraction μ -- O/H diagram agree closely with the positions of field spiral galaxies without oxygen abundance deficiency and are in agreement with the location of one-zone closed-box models. This is strong evidence in favour that the oxygen yield (or, in consequence, the initial mass function) in cluster spiral galaxies does not differ from that in spiral galaxies in the field.

  2. Constraining the Final Fates of Massive Stars by Oxygen and Iron Enrichment History in the Galaxy

    Science.gov (United States)

    Suzuki, Akihiro; Maeda, Keiichi

    2018-01-01

    Recent observational studies of core-collapse supernovae suggest that only stars with zero-age main-sequence masses smaller than 16–18 {M}ȯ explode when they are red supergiants, producing Type IIP supernovae. This may imply that more massive stars produce other types of supernovae or they simply collapse to black holes without giving rise to bright supernovae. This failed supernova hypothesis can lead to significantly inefficient oxygen production because oxygen abundantly produced in inner layers of massive stars with zero-age main-sequence masses around 20–30 {M}ȯ might not be ejected into the surrounding interstellar space. We first assume an unspecified population of oxygen injection events related to massive stars and obtain a model-independent constraint on how much oxygen should be released in a single event and how frequently such events should happen. We further carry out one-box galactic chemical enrichment calculations with different mass ranges of massive stars exploding as core-collapse supernovae. Our results suggest that the model assuming that all massive stars with 9–100 {M}ȯ explode as core-collapse supernovae is still most appropriate in explaining the solar abundances of oxygen and iron and their enrichment history in the Galaxy. The oxygen mass in the Galaxy is not explained when assuming that only massive stars with zero-age main-sequence masses in the range of 9–17 {M}ȯ contribute to the galactic oxygen enrichment. This finding implies that a good fraction of stars more massive than 17 {M}ȯ should eject their oxygen layers in either supernova explosions or some other mass-loss processes.

  3. CONSTRAINING JET PRODUCTION SCENARIOS BY STUDIES OF NARROW-LINE RADIO GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, Marek [Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland); Stasinska, Grazyna [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, Place Jules Janssen, F-92190 Meudon (France); Koziel-Wierzbowska, Dorota [Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Krakow (Poland); Madejski, Greg M. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Asari, Natalia V., E-mail: sikora@camk.edu.pl [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-03-01

    We study a large sample of narrow-line radio galaxies (NLRGs) with extended radio structures. Using 1.4 GHz radio luminosities L {sub 1.4}, narrow optical emission line luminosities L {sub [OIII]} and L{sub H{sub {alpha}}}, as well as black hole masses M {sub BH} derived from stellar velocity dispersions measured from the optical spectra obtained with the Sloan Digital Sky Survey, we find that (1) NLRGs cover about four decades of the Eddington ratio, {lambda} {identical_to} L {sub bol}/L {sub Edd}{proportional_to}L {sub line}/M {sub BH}; (2) L {sub 1.4}/M {sub BH} strongly correlates with {lambda}; and (3) radio loudness, R{identical_to}L{sub 1.4}/L{sub line}, strongly anti-correlates with {lambda}. A very broad range of the Eddington ratio indicates that the parent population of NLRGs includes both radio-loud quasars (RLQs) and broad-line radio galaxies (BLRGs). The correlations they obey and their high jet production efficiencies favor a jet production model which involves the so-called magnetically choked accretion scenario. In this model, production of the jet is dominated by the Blandford-Znajek mechanism, and the magnetic fields in the vicinity of the central black hole are confined by the ram pressure of the accretion flow. Since large net magnetic flux accumulated in central regions of the accretion flow required by the model can take place only via geometrically thick accretion, we speculate that the massive, 'cold' accretion events associated with luminous emission-line active galactic nucleus can be accompanied by an efficient jet production only if preceded by a hot, very sub-Eddington accretion phase.

  4. EVOLUTION OF GROUP GALAXIES FROM THE FIRST RED-SEQUENCE CLUSTER SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Li, I. H. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia); Yee, H. K. C. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Hsieh, B. C. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Gladders, M., E-mail: tli@astro.swin.edu.au, E-mail: hyee@astro.utoronto.ca, E-mail: bchsieh@asiaa.sinica.edu.tw, E-mail: gladders@oddjob.uchicago.edu [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave, Chicago, IL 60637 (United States)

    2012-04-20

    We study the evolution of the red-galaxy fraction (f{sub red}) in 905 galaxy groups with 0.15 {<=} z < 0.52. The galaxy groups are identified by the 'probability friends-of-friends' algorithm from the first Red-Sequence Cluster Survey (RCS1) photometric-redshift sample. There is a high degree of uniformity in the properties of the red sequence of the group galaxies, indicating that the luminous red-sequence galaxies in the groups are already in place by z {approx} 0.5 and that they have a formation epoch of z {approx}> 2. In general, groups at lower redshifts exhibit larger f{sub red} than those at higher redshifts, showing a group Butcher-Oemler effect. We investigate the evolution of f{sub red} by examining its dependence on four parameters, one of which can be classified as intrinsic and three of which can be classified as environmental: galaxy stellar mass (M{sub *}), total group stellar mass (M{sub *,grp}, a proxy for group halo mass), normalized group-centric radius (r{sub grp}), and local galaxy density ({Sigma}{sub 5}). We find that M{sub *} is the dominant parameter such that there is a strong correlation between f{sub red} and galaxy stellar mass. Furthermore, the dependence of f{sub red} on the environmental parameters is also a strong function of M{sub *}. Massive galaxies (M{sub *} {approx}> 10{sup 11} M{sub Sun }) show little dependence of f{sub red} on r{sub grp}, M{sub *,grp}, and {Sigma}{sub 5} over the redshift range. The dependence of f{sub red} on these parameters is primarily seen for galaxies with lower masses, especially for M{sub *} {approx}< 10{sup 10.6} M{sub Sun }. We observe an apparent 'group down-sizing' effect, in that galaxies in lower-mass halos, after controlling for galaxy stellar mass, have lower f{sub red}. We find a dependence of f{sub red} on both r{sub grp} and {Sigma}{sub 5} after the other parameters are controlled. At a fixed r{sub grp}, there is a significant dependence of f{sub red} on {Sigma}{sub 5

  5. Non-Markovian Monte Carlo Algorithm for the Constrained Markovian Evolution in QCD

    CERN Document Server

    Jadach, Stanislaw

    2005-01-01

    We revisit the challenging problem of finding an efficient Monte Carlo (MC) algorithm solving the constrained evolution equations for the initial-state QCD radiation. The type of the parton (quark, gluon) and the energy fraction x of the parton exiting emission chain (entering hard process) are predefined, i.e. constrained throughout the evolution. Such a constraint is mandatory for any realistic MC for the initial state QCD parton shower. We add one important condition: the MC algorithm must not require the a priori knowledge of the full numerical exact solutions of the evolution equations, as is the case in the popular ``Markovian MC for backward evolution''. Our aim is to find at least one solution of this problem that would function in practice. Finding such a solution seems to be definitely within the reach of the currently available computer CPUs and the sophistication of the modern MC techniques. We describe in this work the first example of an efficient solution of this kind. Its numerical implementat...

  6. Feeding, Feedback and the Growth of Galaxies - Molecules as Tools for Probing Galaxy Evolution

    Science.gov (United States)

    Aalto, Susanne

    2017-06-01

    Cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei. Particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (LIRGs/ULIRGs). These dusty objects are of key importance to galaxy mass assembly over cosmic time. Some (U)LIRGS have deeply embedded galaxy nuclei that harbour a very active evolutionary stage of AGNs and/or starbursts. The nuclear activity will often drive mechanical feedback in the form of molecular winds, jets and outflows. This feedback can for example remove baryons from low-mass galaxies, prevent overgrowth of galaxies, be linked to the M_{BH}-σ relation, and explain "red-and dead" properties of local ellipticals. With the ALMA and NOEMA telescopes we can use molecules as diagnostic tools to probe the properties of dust-enshrouded galaxy nuclei and their associated cold winds and outflows. Their morphology, velocity structure, physical conditions and even chemistry can be studied at unprecedented sensitivity and resolution, opening new avenues to further our understanding of the growth of galaxies. I will give a brief review of the ALMA/NOEMA view of AGN and starburst radiative and mechanical feedback, and how it is linked to the properties of the nuclear power source. I will discuss the use of molecules (e.g. H_2O, H_3O^{+}, HCN, HCO^+, H_2S) for studying dusty nuclei and the nature of the embedded activity. We can, for example, investigate ionization rates and the impact of cosmic ray-, X-ray- and PDR-chemistry and the onset of outflows and winds. Interestingly, in some deeply obscured nuclei the chemistry shows strong similarities to that of Galactic hot cores. Finally I will show peculiar molecular jets and very recent ALMA observations at resolutions of tens of milli-arcseconds (few pc) of vibrationally excited HCN in opaque nuclei. These regions

  7. E+A Galaxy Properties and Post-Starburst Galaxy Evolution Data through SDSS-IV MaNGA and Illustris: A Co-Analysis

    Science.gov (United States)

    Ojanen, Winonah; Dudley, Raymond; Edwards, Kay; Gonzalez, Andrea; Johnson, Amalya; Kerrison, Nicole; Marinelli, Mariarosa; Melchert, Nancy; Liu, Charles; Sloan Collaboration, SDSS-IV MaNGA

    2018-01-01

    E+A galaxies (Elliptical + A-type stars) are post-starburst galaxies that have experienced a sudden quenching phase. Using previous research methods, 39 candidates out of 2,812 galaxies observed, or 1.4%, were selected from the SDSS-IV MaNGA survey. We then identified morphological characteristics of the 39 galaxies including stellar kinematics, Gini coefficient, gas density and distribution and stellar ages. To study the origin of how E+A galaxies evolved to their present state, galaxy simulation data from the Illustris simulation was utilized to identify similar quenched post-starburst candidates. Seven post-starburst candidates were identified through star formation rate histories of Illustris simulated galaxies. The evolution of these galaxies is studied from 0 to 13.8 billion years ago to identify what caused the starburst and quenching of the Illustris candidates. Similar morphological characteristics of Illustris post-starburst candidates are pulled from before, during, and post-starburst and compared to the same morphological characteristics of the E+A galaxies from SDSS-IV MaNGA. The characteristics and properties of the Illustris galaxies are used to identify the possible evolutionary histories of the observed E+A galaxies. This work was supported by grants AST-1460860 from the National Science Foundation and SDSS FAST/SSP-483 from the Alfred P. Sloan Foundation to the CUNY College of Staten Island.

  8. Constraining the contribution of galaxies and active galactic nuclei to cosmic reionization

    Science.gov (United States)

    Yoshiura, Shintaro; Hasegawa, Kenji; Ichiki, Kiyotomo; Tashiro, Hiroyuki; Shimabukuro, Hayato; Takahashi, Keitaro

    2017-11-01

    Understanding the detailed process of cosmic reionization is one of the remaining problems in astrophysics and cosmology. Here we construct a model of cosmic reionization that includes contributions from high-z galaxies and active galactic nuclei (AGNs) and calculate reionization and thermal histories with the model. To keep the model general and realistic, we vary the escape fraction of ionizing photons, fesc, and the faint-end slope of the AGN luminosity function at high redshifts, αhz, within constraints from the observed cosmic star formation history and observed bright-end UV luminosity functions at z ≤ 6. Additionally, we model the spectral energy distribution (SED) of AGNs, which depends on the Eddington ratio and the black hole mass. By comparing the computed reionization histories with the observed H I fractions and the optical depth for Thomson scattering from Planck, we find that αhz > -1.5 and fesc SED has a significant impact on the thermal history. Therefore it is expected that measurements of the thermal state of the intergalactic medium (IGM) will provide useful information on the properties of ionizing sources.

  9. Are Cooling Flows Governing E-Galaxy Evolution

    NARCIS (Netherlands)

    Valentijn, E. A.; de Zeeuw, P.T.

    1987-01-01

    Gas accretion of intracluster gas into the potential well of giant elliptical or cD galaxies can provide the material for both nuclear non-thermal activity and continuous, probably low mass, star formation. The cooling accretion flows could lead to the original formation of the visible object, and

  10. The dynamical and chemical evolution of dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Revaz, Y.; Jablonka, P.; Sawala, T.; Hill, V.; Letarte, B.; Irwin, M.; Battaglia, G.; Helmi, A.; Shetrone, M. D.; Tolstoy, E.; Venn, K. A.

    We present a large sample of fully self-consistent hydrodynamical Nbody/Tree-SPH simulations of isolated dwarf spheroidal galaxies (dSphs). It has enabled us to identify the key physical parameters and mechanisms at the origin of the observed variety in the Local Group dSph properties. The initial

  11. Combining Galaxy-Galaxy Lensing and Galaxy Clustering

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngsoo [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Krause, Elisabeth [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Dodelson, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Jain, Bhuvnesh [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Amara, Adam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Becker, Matt [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bridle, Sarah [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Clampitt, Joseph [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Crocce, Martin [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Honscheid, Klaus [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gaztanaga, Enrique [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sanchez, Carles [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wechsler, Risa [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-01-01

    Combining galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth rate of large scale structure, a quantity that will shed light on the mechanism driving the acceleration of the Universe. The Dark Energy Survey (DES) is a prime candidate for such an analysis, with its measurements of both the distribution of galaxies on the sky and the tangential shears of background galaxies induced by these foreground lenses. By constructing an end-to-end analysis that combines large-scale galaxy clustering and small-scale galaxy-galaxy lensing, we also forecast the potential of a combined probes analysis on DES datasets. In particular, we develop a practical approach to a DES combined probes analysis by jointly modeling the assumptions and systematics affecting the different components of the data vector, employing a shared halo model, HOD parametrization, photometric redshift errors, and shear measurement errors. Furthermore, we study the effect of external priors on different subsets of these parameters. We conclude that DES data will provide powerful constraints on the evolution of structure growth in the universe, conservatively/ optimistically constraining the growth function to 8%/4.9% with its first-year data covering 1000 square degrees, and to 4%/2.3% with its full five-year data covering 5000 square degrees.

  12. Galaxy evolution in the metric of the cosmic web

    Science.gov (United States)

    Kraljic, K.; Arnouts, S.; Pichon, C.; Laigle, C.; de la Torre, S.; Vibert, D.; Cadiou, C.; Dubois, Y.; Treyer, M.; Schimd, C.; Codis, S.; de Lapparent, V.; Devriendt, J.; Hwang, H. S.; Le Borgne, D.; Malavasi, N.; Milliard, B.; Musso, M.; Pogosyan, D.; Alpaslan, M.; Bland-Hawthorn, J.; Wright, A. H.

    2018-02-01

    The role of the cosmic web in shaping galaxy properties is investigated in the Galaxy And Mass Assembly (GAMA) spectroscopic survey in the redshift range 0.03 ≤ z ≤ 0.25. The stellar mass, u - r dust corrected colour and specific star formation rate (sSFR) of galaxies are analysed as a function of their distances to the 3D cosmic web features, such as nodes, filaments and walls, as reconstructed by DisPerSE. Significant mass and type/colour gradients are found for the whole population, with more massive and/or passive galaxies being located closer to the filament and wall than their less massive and/or star-forming counterparts. Mass segregation persists among the star-forming population alone. The red fraction of galaxies increases when closing in on nodes, and on filaments regardless of the distance to nodes. Similarly, the star-forming population reddens (or lowers its sSFR) at fixed mass when closing in on filament, implying that some quenching takes place. These trends are also found in the state-of-the-art hydrodynamical simulation HORIZON-AGN. These results suggest that on top of stellar mass and large-scale density, the traceless component of the tides from the anisotropic large-scale environment also shapes galactic properties. An extension of excursion theory accounting for filamentary tides provides a qualitative explanation in terms of anisotropic assembly bias: at a given mass, the accretion rate varies with the orientation and distance to filaments. It also explains the absence of type/colour gradients in the data on smaller, non-linear scales.

  13. VLT/UVES abundances in four nearby dwarf spheroidal galaxies. II. Implications for understanding galaxy evolution

    NARCIS (Netherlands)

    Tolstoy, E; Venn, KA; Shetrone, M; Primas, F; Hill, [No Value; Kaufer, A; Szeifert, T

    We have used the Ultraviolet Visual-Echelle Spectrograph (UVES) on Kueyen (UT2) of the Very Large Telescope to take spectra of 15 individual red giant stars in the centers of four nearby dwarf spheroidal galaxies (dSph's) : Sculptor, Fornax, Carina, and Leo I. We measure the abundance variations of

  14. When galaxy clusters collide : the impact of merger shocks on cluster gas and galaxy evolution

    NARCIS (Netherlands)

    Stroe, Andra

    2015-01-01

    Galaxy clusters mainly grow through mergers with other clusters and groups. Major mergers give rise to cluster-wide traveling shocks, which can be detected at radio wavelengths as relics: elongated, diffuse synchrotron emitting areas located at the periphery of merging clusters. The 'Sausage'

  15. Protein structure and evolution: are they constrained globally by a principle derived from information theory?

    Science.gov (United States)

    Hatton, Leslie; Warr, Gregory

    2015-01-01

    That the physicochemical properties of amino acids constrain the structure, function and evolution of proteins is not in doubt. However, principles derived from information theory may also set bounds on the structure (and thus also the evolution) of proteins. Here we analyze the global properties of the full set of proteins in release 13-11 of the SwissProt database, showing by experimental test of predictions from information theory that their collective structure exhibits properties that are consistent with their being guided by a conservation principle. This principle (Conservation of Information) defines the global properties of systems composed of discrete components each of which is in turn assembled from discrete smaller pieces. In the system of proteins, each protein is a component, and each protein is assembled from amino acids. Central to this principle is the inter-relationship of the unique amino acid count and total length of a protein and its implications for both average protein length and occurrence of proteins with specific unique amino acid counts. The unique amino acid count is simply the number of distinct amino acids (including those that are post-translationally modified) that occur in a protein, and is independent of the number of times that the particular amino acid occurs in the sequence. Conservation of Information does not operate at the local level (it is independent of the physicochemical properties of the amino acids) where the influences of natural selection are manifest in the variety of protein structure and function that is well understood. Rather, this analysis implies that Conservation of Information would define the global bounds within which the whole system of proteins is constrained; thus it appears to be acting to constrain evolution at a level different from natural selection, a conclusion that appears counter-intuitive but is supported by the studies described herein.

  16. THERMAL AND CHEMICAL EVOLUTIONS OF GALAXY CLUSTERS OBSERVED WITH SUZAKU

    Directory of Open Access Journals (Sweden)

    Kosuke Sato

    2013-12-01

    Full Text Available We studied the properties of the intracluster medium (ICM of galaxy clusters to outer regions observed with Suzaku. The observed temperature dropped by about ~30% from the central region to the virial radius of the clusters. The derived entropy profile agreed with the expectation from simulations within r500, while the entropy profile in r > r500 indicated a flatter slope than the simulations. This would suggest that the cluster outskirts were out of hydrostatic equilibrium. As for the metallicity, we studied the metal abundances from O to Fe up to ~0.5 times the virial radius of galaxy groups and clusters. Comparing the results with supernova nucleosynthesis models, the number ratio of type II to Ia supernovae is estimated to be ~3.5. We also calculated not only Fe, but also O and Mg mass-to-light ratios (MLRs with K-band luminosity. The MLRs in the clusters had a similar feature.

  17. Interpreting the evolution of galaxy colours from z = 8 to 5

    NARCIS (Netherlands)

    Mancini, Mattia; Schneider, Raffaella; Graziani, Luca; Valiante, Rosa; Dayal, Pratika; Maio, Umberto; Ciardi, Benedetta

    2016-01-01

    We attempt to interpret existing data on the evolution of the UV luminosity function and UV colours, β, of galaxies at 5 ≤ z ≤ 8, to improve our understanding of their dust content and interstellar medium properties. To this aim, we post-process the results of a cosmological hydrodynamical

  18. Evolution of the Galaxy and the Birth of the Solar System: The Short ...

    Indian Academy of Sciences (India)

    Sahijpal & Gupta 2013). Apart from understanding the entire temporal evolution of the galaxy, one of the major emphasis in developing the GCE models is to under- stand the origin of stable isotopic abundance of the solar system (Anders & Grevesse. 1989; Asplund et al. 2009). The solar system formed around 4.56 Gyr ...

  19. Cosmic Star Formation History and Evolution of the Galaxy UV Luminosity Function for z < 1

    Science.gov (United States)

    Zhang, Keming; Schiminovich, David

    2018-01-01

    We present the latest constraints on the evolution of the far-ultraviolet luminosity function of galaxies (1500 Å, UVLF hereafter) for 0 accounted for by contributions from AGN. We also describe our methodology, which can be applied more generally to any combination of wide-shallow and deep-narrow surveys.

  20. Evolution of the BCG in Disturbed Galaxy Clusters

    Science.gov (United States)

    Ardila, Felipe; Strauss, Michael A.; Lauer, Tod R.; Postman, Marc

    2017-01-01

    The present paradigm in cosmology tells us that large-scale structures grow hierarchically. This suggests that galaxy clusters grow by accreting mass and merging with other clusters, a process which should be detectable by the presence of substructure within a cluster. Using the Dressler-Shectman (DS) three-dimensional test for dynamical substructure, we determined which clusters showed evidence for disturbance from a set of 227 Abell clusters from Lauer et al. (2014) with at least 50 member galaxies and spectroscopic redshifts, z BCG luminosities (Lm), but not in their BCG stellar velocity dispersions (σ), their BCG spatial offsets from the x-ray centers of the clusters, their BCG velocity offsets from the mean cluster velocity, the logarithmic slopes of their BCG photometric curves of growth (α), their cluster velocity dispersions, or their luminosity differences between the BCG and the second-ranked galaxy in the cluster (M2). Similarly, no significant difference was found in the fitting of the Lm-α-σ metric plane for BCGs of clusters with substructure compared those in which there is not substructure. This is surprising since our hierarchical growth models suggest that some of these BCG/cluster properties would be affected by a disturbance of the cluster, indicating that our understanding of how BCGs evolve with their clusters is incomplete and we should explore other ways to probe the level of disturbance.

  1. Shell evolution at N = 20 in the constrained relativistic mean field approach

    Science.gov (United States)

    SUN, Bao-Hua; LI, Jian

    2008-11-01

    The shell evolution at N = 20, a disappearing neutron magic number observed experimentally in very neutron-rich nuclides, is investigated in the constrained relativistic mean field (RMF) theory. The trend of the shell closure observed experimentally towards the neutron drip-line can be reproduced. The predicted two-neutron separation energies, neutron shell gap energies and deformation parameters of ground states are shown as well. These results are compared with the recent Hartree-Fock-Bogliubov (HFB-14) model and the available experimental data. The perspective towards a better understanding of the shell evolution is discussed. Supported by Major State Basic Research Developing Program (2007CB815000), and National Natural Science Foundation of China (10435010, 10775004, 10221003)

  2. Constraining the Nature of Dark Matter with the Star-formation History of the Faintest Local Group Dwarf Galaxy Satellites

    Energy Technology Data Exchange (ETDEWEB)

    Chau, Alice; Mayer, Lucio [Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Governato, Fabio [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States)

    2017-08-10

    Λ warm dark matter (ΛWDM), realized by collisionless particles of 1–3 keV, has been proposed as an alternative scenario to Λ-Cold-Dark Matter (ΛCDM) for the dwarf galaxy scale discrepancies. We present an approach to test the viability of such WDM models using star-formation histories (SFHs) of the dwarf spheroidal galaxies (dSphs) in the Local Group. We compare their high-time-resolution SFHs with the collapse redshift of their dark halos in CDM and WDM. Collapse redshift is inferred after determining the subhalo infall mass. This is based on the dwarf current mass inferred from stellar kinematics, combined with cosmological simulation results on subhalo evolution. WDM subhalos close to the filtering mass scale, forming significantly later than CDM, are the most difficult to reconcile with early truncation of star formation ( z ≥ 3). The ultra-faint dwarfs (UFDs) provide the most stringent constraints. Using six UFDs and eight classical dSphs, we show that a 1 keV particle is strongly disfavored, consistently with other reported methods. Excluding other models is only hinted for a few UFDs. Other UFDs for which the lack of robust constraints on halo mass prevents us from carrying out our analysis rigorously, show a very early onset of star formation that will strengthen the constraints delivered by our method in the future. We discuss the various caveats, notably the low number of dwarfs with accurately determined SFHs and the uncertainties when determining the subhalo infall mass, most notably the baryonic physics. Our preliminary analysis may serve as a pathfinder for future investigations that will combine accurate SFHs for local dwarfs with direct analysis of WDM simulations with baryons.

  3. What drives the evolution of Luminous Compact Blue Galaxies in Clusters vs. the Field?

    Science.gov (United States)

    Wirth, Gregory

    2017-08-01

    Present-day galaxy clusters consist chiefly of low-mass dwarf elliptical galaxies, but the progenitors of this dominant population remain unclear. A prime candidate is the class of objects known as Luminous Compact Blue Galaxies, common in intermediate-reshift clusters but virtually extinct today. Recent cosmological simulations suggest that the present-day dwarfs galaxies begin as irregular field galaxies, undergo an environmentally-driven starburst phase as they enter the cluster, and stop forming stars earlier than their counterparts in the field. This model predicts that cluster dwarfs should have lower stellar mass per unit dynamical mass than their counterparts in the field. We propose a two-pronged archival research program to test this key prediction using the combination of precision photometry from space and high-quality spectroscopy. First, we will combine optical HST/ACS imaging of five z=0.55 clusters (including two HST Frontier Fields) with Spitzer IR imaging and publicly-released Keck/DEIMOS spectroscopy to measure stellar-to-dynamical-mass ratios for a large sample of cluster LCBGs. Second, we will exploit a new catalog of LCBGs in the COSMOS field to gather corresponding data for a significant sample of field LCBGs. By comparing mass ratios from these datasets, we will test theoretical predictions and determine the primary physical driver of cluster dwarf-galaxy evolution.

  4. Predictions of ΛCDM eulerian hydrodynamic simulations on galaxy formation and evolution

    Science.gov (United States)

    Nagamine, Kentaro

    2001-10-01

    The purpose of this thesis is to investigate the validity of the cold dark matter (CDM) model by comparing the predictions of large-scale hydrodynamic simulations with variety of available astronomical data on galaxies. The simulations we use include a heuristic star formation recipe which allows us to study galaxy formation without making any ad hoc assumptions on the bias of galaxy distribution relative to underlying dark matter distribution. Our simulation also have additional unique features of self-consistent treatment of supernovae feedback, ultra-violet radiation field, radiation shielding, metal enrichment and metal cooling. Furthermore, a population synthesis model is used to make predictions in terms of observable light. Firstly, we discuss star formation history, stellar metallicity distribution, mass function, luminosity function, and colors of galaxies in a ΛCDM universe, both in the local universe and as functions of time. Secondly, we study the evolution of Lyman Break Galaxies at redshift 3, with particular emphasis on their star formation history, merger history, and metallicity distribution. Finally, the cosmic Mach number and its environmental dependence on overdensity and galaxy mass and age is studied. The overall picture is that there is an impressive, though imperfect match between theory, numerical simulations, and observations.

  5. SEMI-ANALYTIC GALAXY EVOLUTION (SAGE): MODEL CALIBRATION AND BASIC RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Croton, Darren J.; Stevens, Adam R. H.; Tonini, Chiara; Garel, Thibault; Bernyk, Maksym; Bibiano, Antonio; Hodkinson, Luke; Mutch, Simon J.; Poole, Gregory B.; Shattow, Genevieve M. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122 (Australia)

    2016-02-15

    This paper describes a new publicly available codebase for modeling galaxy formation in a cosmological context, the “Semi-Analytic Galaxy Evolution” model, or sage for short.{sup 5} sage is a significant update to the 2006 model of Croton et al. and has been rebuilt to be modular and customizable. The model will run on any N-body simulation whose trees are organized in a supported format and contain a minimum set of basic halo properties. In this work, we present the baryonic prescriptions implemented in sage to describe the formation and evolution of galaxies, and their calibration for three N-body simulations: Millennium, Bolshoi, and GiggleZ. Updated physics include the following: gas accretion, ejection due to feedback, and reincorporation via the galactic fountain; a new gas cooling–radio mode active galactic nucleus (AGN) heating cycle; AGN feedback in the quasar mode; a new treatment of gas in satellite galaxies; and galaxy mergers, disruption, and the build-up of intra-cluster stars. Throughout, we show the results of a common default parameterization on each simulation, with a focus on the local galaxy population.

  6. ATLAS Probe: Exploring Frontiers in Galaxy Evolution, Cosmology, and Milky Way Science

    Science.gov (United States)

    Wang, Yun; Robberto, Massimo; Dickinson, Mark; Ferguson, Henry C.; Hillenbrand, Lynne; Hirata, Christopher M.; Cimatti, Andrea; Bartlett, James; Barkhouser, Robert; Benjamin, Robert A.; Brinchmann, Jarle; Chary, Ranga-Ram; Conroy, Charlie; Daddi, Emanuele; Donahue, Megan; Dore, Olivier; Eisenhardt, Peter; Fraser, Wesley C.; Helou, George; Kirkpatrick, J. Davy; Malhotra, Sangeeta; Moscardini, Lauro; Ninkov, Zoran; Ressler, Michael; Rhoads, James; Rhodes, Jason; Shapley, Alice; Smee, Stephen; ATLAS Probe Team

    2018-01-01

    ATLAS (Astrophysics Telescope for Large Area Spectroscopy) Probe is a concept for a NASA probe-class space mission that leverages WFIRST imaging for targeted spectroscopy. ATLAS Probe will obtain spectra of 90% of all galaxies imaged by the WFIRST High Latitude Survey at z > 0.5, with slit spectra of 300 million galaxies to z = 7. ATLAS Probe and WFIRST together will produce a 3D map of the Universe with Mpc resolution over 2200 sq deg, the definitive data sets for studying galaxy evolution, probing dark matter, dark energy and modification of general relativity, and quantifying the 3D structure and stellar content of the Milky Way.ATLAS Probe science spans four broad categories: (1) Revolutionize galaxy evolution studies by tracing the relation between galaxies and dark matter from the local group to cosmic voids and filaments, from the epoch of reionization through the peak era of galaxy assembly. (2) Open a new window into the Universe by mapping the dark matter filaments using 3D weak lensing with spectroscopic redshifts to unveil the nature of the dark Universe, and obtaining definitive measurements of dark energy and possible modification of general relativity using cosmic large-scale structure. (3) Probe the Milky Way's dust-shrouded regions, reaching the far side of our Galaxy. (4) Characterize asteroids and comets in the outer Solar System.ATLAS Probe is a 1.5m telescope with a field of view (FoV) of 0.4 sq deg, and uses Digital Micromirror Devices (DMDs) as slit selectors. It has a spectroscopic resolution of R = 600, and a wavelength range of 1-4μm. The lack of slit spectroscopy from space over a wide FoV is the obvious gap in current and planned future space missions; ATLAS fills this big gap with an unprecedented spectroscopic capability (with an estimated spectroscopic multiplex factor of 5000-10000). It has an estimated cost under $1B, with a single instrument, a telescope aperture that allows for a lighter launch vehicle, and mature technology

  7. The evolution of C/O in dwarf galaxies from Hubble Space Telescope FOS observations

    Science.gov (United States)

    Garnett, D. R.; Skillman, E. D.; Dufour, R. J.; Peimbert, M.; Torres-Peimbert, S.; Terlevich, R.; Terlevich, E.; Shields, G. A.

    1995-01-01

    We present UV observations of seven H II regions in low-luminosity dwarf irregular galaxies and the Magellanic Clouds obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) in order to measure the C/O abundance ratio in the interstellar medium (ISM) of those galaxies. We measure both O III 1666 A and C III 1909 A in our spectra, enabling us to determine C(+2)/O(+2) with relatively small uncertainties. The results from our HST observations show a continuous increase in C/O with increasing O/H, consistent with a power law having an index of 0.43 +/- 0.09 over the range -4.7 to -3.6 in log (O/H). One possible interpretation of this trend is that the most metal-poor galaxies are the youngest and dominated by the products of early enrichment by massive stars, while more metal-rich galaxies show increasing, delayed contributions of carbon from intermediate-mass stars. Our results also suggest that it may not be appropiate to combine abundances in irregular galaxies with those in spiral galaxies to study the evolution of chemical abundances. Our measured C/O ratios in the most metal-poor galaxies are consistent with predictions of nucleosynthesis from massive stars for Weaver & Woosley's best estimate for the 12C(alpha, gamma) 16O nuclear reaction rate, assuming negligible contanmination from carbon produced in intermediate-mass stars in these galaxies. We detect a weak N III 1750 A multiplet in SMC N88A and obtain interesting upper limits for two other objects. Our 2 sigma uppr limits on the 1750 A feature indicate that the N(+2)/O(+2) ratios in these objects are not significantly larger than the N(+)/O(+) ratios measured from optical spectra. This behavior is consistent with predictions of photionization models, although better detections of N III are needed to confirm the results.

  8. Strong Stellar-driven Outflows Shape the Evolution of Galaxies at Cosmic Dawn

    Energy Technology Data Exchange (ETDEWEB)

    Fontanot, Fabio; De Lucia, Gabriella [INAF—Astronomical Observatory of Trieste, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Hirschmann, Michaela [Sorbonne Universités, UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, F-75014 Paris (France)

    2017-06-20

    We study galaxy mass assembly and cosmic star formation rate (SFR) at high redshift (z ≳ 4), by comparing data from multiwavelength surveys with predictions from the GAlaxy Evolution and Assembly (gaea) model. gaea implements a stellar feedback scheme partially based on cosmological hydrodynamical simulations, which features strong stellar-driven outflows and mass-dependent timescales for the re-accretion of ejected gas. In previous work, we have shown that this scheme is able to correctly reproduce the evolution of the galaxy stellar mass function (GSMF) up to z ∼ 3. We contrast model predictions with both rest-frame ultraviolet (UV) and optical luminosity functions (LFs), which are mostly sensitive to the SFR and stellar mass, respectively. We show that gaea is able to reproduce the shape and redshift evolution of both sets of LFs. We study the impact of dust on the predicted LFs, and we find that the required level of dust attenuation is in qualitative agreement with recent estimates based on the UV continuum slope. The consistency between data and model predictions holds for the redshift evolution of the physical quantities well beyond the redshift range considered for the calibration of the original model. In particular, we show that gaea is able to recover the evolution of the GSMF up to z ∼ 7 and the cosmic SFR density up to z ∼ 10.

  9. Dissecting galaxy formation models with sensitivity analysis—a new approach to constrain the Milky Way formation history

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, Facundo A.; O' Shea, Brian W. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Coleman-Smith, Christopher E. [Department of Physics, Duke University, Durham, NC 27708 (United States); Tumlinson, Jason [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Wolpert, Robert L. [Department of Statistical Science, Duke University, Durham, NC 27708-0251 (United States)

    2014-05-20

    We present an application of a statistical tool known as sensitivity analysis to characterize the relationship between input parameters and observational predictions of semi-analytic models of galaxy formation coupled to cosmological N-body simulations. We show how a sensitivity analysis can be performed on our chemo-dynamical model, ChemTreeN, to characterize and quantify its relationship between model input parameters and predicted observable properties. The result of this analysis provides the user with information about which parameters are most important and most likely to affect the prediction of a given observable. It can also be used to simplify models by identifying input parameters that have no effect on the outputs (i.e., observational predictions) of interest. Conversely, sensitivity analysis allows us to identify what model parameters can be most efficiently constrained by the given observational data set. We have applied this technique to real observational data sets associated with the Milky Way, such as the luminosity function of the dwarf satellites. The results from the sensitivity analysis are used to train specific model emulators of ChemTreeN, only involving the most relevant input parameters. This allowed us to efficiently explore the input parameter space. A statistical comparison of model outputs and real observables is used to obtain a 'best-fitting' parameter set. We consider different Milky-Way-like dark matter halos to account for the dependence of the best-fitting parameter selection process on the underlying merger history of the models. For all formation histories considered, running ChemTreeN with best-fitting parameters produced luminosity functions that tightly fit their observed counterpart. However, only one of the resulting stellar halo models was able to reproduce the observed stellar halo mass within 40 kpc of the Galactic center. On the basis of this analysis, it is possible to disregard certain models, and their

  10. ZFOURGE/CANDELS: ON THE EVOLUTION OF M* GALAXY PROGENITORS FROM z = 3 TO 0.5

    Energy Technology Data Exchange (ETDEWEB)

    Papovich, C.; Quadri, R.; Tilvi, V.; Tran, K.-V. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Labbé, I.; Straatman, C. M. S. [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Behroozi, P.; Ferguson, H. C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bell, E. F. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Glazebrook, K.; Kacprzak, G. G. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Spitler, L.; Cowley, M. [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); Davé, R. [University of the Western Cape, Bellville, Cape Town 7535 (South Africa); Dekel, A. [Center of Astrophysics and Planetary Sciences, Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Dickinson, M.; Inami, H. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85721 (United States); Finkelstein, S. L. [Department of Astronomy, University of Texas, Austin, TX 78712 (United States); Gawiser, E. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Faber, S. M., E-mail: papovich@tamu.edu [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); and others

    2015-04-10

    Galaxies with stellar masses near M* contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M*, at 5 × 10{sup 10} M {sub ☉} (defined here to be MW-mass) and 10{sup 11} M {sub ☉} (defined to be M31-mass). We study the typical progenitors of these galaxies using the FOURSTAR Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z ∼ 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M* galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z ∼ 0 and are strongly anticorrelated with an increase in the S

  11. Galaxy evolution. Black hole feedback in the luminous quasar PDS 456.

    Science.gov (United States)

    Nardini, E; Reeves, J N; Gofford, J; Harrison, F A; Risaliti, G; Braito, V; Costa, M T; Matzeu, G A; Walton, D J; Behar, E; Boggs, S E; Christensen, F E; Craig, W W; Hailey, C J; Matt, G; Miller, J M; O'Brien, P T; Stern, D; Turner, T J; Ward, M J

    2015-02-20

    The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution. Copyright © 2015, American Association for the Advancement of Science.

  12. The Tully-Fisher Relation and the dynamical evolution of galaxies

    Science.gov (United States)

    De Rossi, M. E.; Tissera, P. B.; Pedrosa, S. E.

    We studied the dynamical and kinematical properties of galaxies since z 3 by performing numerical simulations in a CDM universe. Our results sug- gest that the maximum gas-phase rotation velocity of the disc component is a good proxy for the circular velocity at that radius regardless of the galaxy morphology. We also found that velocity scales which combine dispersion and rotation velocity in their definition lead to a tighter Tully-Fisher Rela- tion. In particular, the lowest scatter in the correlation between mass and velocity is obtained if the kinematical indicator is evaluated at the radius corresponding to the maximum of the rotation curve. In these simulations, the evolution of the scatter of the Tully-Fisher Relation seems to be strongly modulating by galaxy interactions and mergers which can drive gas inflows and outflows regulating the star formation process and feedback mecha- nisms inside these systems.

  13. Interpreting the evolution of galaxy colours from z = 8 to 5

    Science.gov (United States)

    Mancini, Mattia; Schneider, Raffaella; Graziani, Luca; Valiante, Rosa; Dayal, Pratika; Maio, Umberto; Ciardi, Benedetta

    2016-11-01

    We attempt to interpret existing data on the evolution of the UV luminosity function and UV colours, β, of galaxies at 5 ≤ z ≤ 8, to improve our understanding of their dust content and interstellar medium properties. To this aim, we post-process the results of a cosmological hydrodynamical simulation with a chemical evolution model, which includes dust formation by supernovae and intermediate-mass stars, dust destruction in supernova shocks, and grain growth by accretion of gas-phase elements in dense gas. We find that observations require a steep, Small Magellanic Cloud-like extinction curve and a clumpy dust distribution, where stellar populations younger than 15 Myr are still embedded in their dusty natal clouds. Investigating the scatter in the colour distribution and stellar mass, we find that the observed trends can be explained by the presence of two populations: younger, less massive galaxies where dust enrichment is mainly due to stellar sources, and massive, more chemically evolved ones, where efficient grain growth provides the dominant contribution to the total dust mass. Computing the IR-excess-UV colour relation, we find that all but the dustiest model galaxies follow a relation shallower than the Meurer et al. one, usually adopted to correct the observed UV luminosities of high-z galaxies for the effects of dust extinction. As a result, their total star formation rates might have been overestimated. Our study illustrates the importance to incorporate a proper treatment of dust in simulations of high-z galaxies, and that massive, dusty, UV-faint galaxies might have already appeared at z ≲ 7.

  14. MUFASA: the strength and evolution of galaxy conformity in various tracers

    Science.gov (United States)

    Rafieferantsoa, Mika; Davé, Romeel

    2018-03-01

    We investigate galaxy conformity using the MUFASA cosmological hydrodynamical simulation. We show a bimodal distribution in galaxy colour with radius, albeit with too many low-mass quenched satellite galaxies compared to observations. MUFASA produces conformity in observed properties such as colour, specific star formation rate (sSFR), and H I content, i.e. neighbouring galaxies have similar properties. We see analogous trends in other properties such as in environment, stellar age, H2 content, and metallicity. We introduce quantifying conformity using S(R), measuring the relative difference in upper and lower quartile properties of the neighbours. We show that low-mass and non-quenched haloes have weak conformity (S(R)≲ 0.5) extending to large projected radii R in all properties, while high-mass and quenched haloes have strong conformity (S(R)˜ 1) that diminishes rapidly with R and disappears at R ≳ 1 Mpc. S(R) is strongest for environment in low-mass haloes, and sSFR (or colour) in high-mass haloes, and is dominated by one-halo conformity with the exception of H I in small haloes. Metallicity shows a curious anticonformity in massive haloes. Tracking the evolution of conformity for z = 0 galaxies back in time shows that conformity broadly emerges as a late-time (z ≲ 1) phenomenon. However, for fixed halo mass bins, conformity is fairly constant with redshift out to z ≳ 2. These trends are consistent with the idea that strong conformity only emerges once haloes grow above MUFASA's quenching mass scale of ˜1012 M⊙. A quantitative measure of conformity in various properties, along with its evolution, thus represents a new and stringent test of the impact of quenching on environment within current galaxy formation models.

  15. Evolution of the mass-metallicity relations in passive and star-forming galaxies from SPH-cosmological simulations

    DEFF Research Database (Denmark)

    Velonà, A. D Romeo; Sommer-Larsen, J.; Napolitano, N. R.

    2013-01-01

    We present results from SPH-cosmological simulations, including self-consistent modeling of supernova feedback and chemical evolution, of galaxies belonging to two clusters and 12 groups. We reproduce the mass-metallicity (ZM) relation of galaxies classified in two samples according to their star...

  16. Further constraints on the evolution of K-s-selected galaxies in the GOODS/CDFS field

    NARCIS (Netherlands)

    Caputi, KI; McLure, RJ; Dunlop, JS; Cirasuolo, M; Schael, AM

    2006-01-01

    We have selected and analysed the properties of a sample of 2905 K-s <21.5 galaxies in similar to 131 arcmin(2) of the Great Observatories Origins Deep Survey (GOODS) Chandra Deep Field South (CDFS), to obtain further constraints on the evolution of K-s-selected galaxies with respect to the results

  17. A new galactic chemical evolution model with dust: results for dwarf irregular galaxies and DLA systems

    Science.gov (United States)

    Gioannini, L.; Matteucci, F.; Vladilo, G.; Calura, F.

    2017-01-01

    We present a galactic chemical evolution model which adopts updated prescriptions for all the main processes governing the dust cycle. We follow in detail the evolution of the abundances of several chemical species (C, O, S, Si, Fe and Zn) in the gas and dust of a typical dwarf irregular galaxy. The dwarf irregular galaxy is assumed to evolve with a low but continuous level of star formation and experience galactic winds triggered by supernova (SN) explosions. We predict the evolution of the gas to dust ratio in such a galaxy and discuss critically the main processes involving dust, such as dust production by asymptotic giant branch stars and Type II SNe, destruction and accretion (gas condensation in clouds). We then apply our model to damped Lyman α (DLA) systems which are believed to be dwarf irregulars, as witnessed by their abundance patterns. Our main conclusions are the following. (i) We can reproduce the observed gas to dust ratio in dwarf galaxies. (ii) We find that the process of dust accretion plays a fundamental role in the evolution of dust and in certain cases it becomes the dominant process in the dust cycle. On the other hand, dust destruction seems to be a negligible process in irregulars. (iii) Concerning DLA systems, we show that the observed gas-phase abundances of silicon, normalized to volatile elements (zinc and sulfur), are in agreement with our model. (iv) The abundances of iron and silicon in DLA systems suggest that the two elements undergo a different history of dust formation and evolution. Our work casts light on the nature of iron-rich dust: the observed depletion pattern of iron is well reproduced only when an additional source of iron dust is considered. Here we explore the possibility of a contribution from Type Ia SNe as well as an efficient accretion of iron nanoparticles.

  18. Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project

    NARCIS (Netherlands)

    Drouart, G.; De Breuck, C.; Vernet, J.; Seymour, N.; Lehnert, M.; Barthel, P.; Bauer, F. E.; Ibar, E.; Galametz, A.; Haas, M.; Hatch, N.; Mullaney, J. R.; Nesvadba, N.; Rocca-Volmerange, B.; Röttgering, H. J. A.; Stern, D.; Wylezalek, D.

    2014-01-01

    We present results from a comprehensive survey of 70 radio galaxies at redshifts 1 2.5 are higher than the sSFR of typical star forming galaxies over the same redshift range, but are similar or perhaps lower than the galaxy population for radio galaxies at z<2.5. By comparing the sSFR and the

  19. Towards Understanding the Star Formation-Feedback Loop in Galaxy Formation and Evolution

    Science.gov (United States)

    Kravtsov, Andrey

    We propose to carry out a comprehensive study of how star formation and feedback loop influences evolution of galaxies using a suite of ultra-high resolution cosmological simulations of galaxy formation using the Adaptive Mesh Refinement (AMR) approach implemented in the Adaptive Refinement Tree (ART) code. The simulations will result in the numerical models of galaxy evolution of unprecedented resolution and sophistication of the processes included. Our code includes treatment of a wide spectrum of processes critical for realistic modeling of galaxy formation from the primordial chemistry of hydrogen and helium species, radiative transfer of ionizing radiation, to the metallicity- dependent cooling, chemistry of molecular hydrogen on dust and treatment of radiative transfer of dissociating far ultraviolet radiation. The latter allows us to tie star formation with dense, molecular regions capable of self-shielding from heating radiation and avoid adopting arbitrary density and temperature thresholds for star formation. Simulations will also employ a new model for momentum injection due to radiation pressure exerted by young massive stars onto surrounding dust and gas. This early, pre-supernova feedback is critical to prompt dispersal of natal molecular clouds and regulating star formation efficiency and increasing efficiency of energy release by supernovae. The simulations proposed in this project will therefore treat the most important process to understanding the efficiency of baryon conversion to stars - the star formation - in the way most closely resembling the actual star formation observed in galaxies and stellar feedback model that is firmly rooted in observational evidence on how feedback operates in real molecular clouds. The simulations we propose will provide models of galaxy evolution during three important epochs in the history of the universe: (1) early evolution prior to and during the reionization of the universe (the first billion years of

  20. Connecting traces of galaxy evolution: the missing core mass-morphological fine structure relation

    Science.gov (United States)

    Bonfini, P.; Bitsakis, T.; Zezas, A.; Duc, P.-A.; Iodice, E.; González-Martín, O.; Bruzual, G.; González Sanoja, A. J.

    2018-01-01

    Deep exposure imaging of early-type galaxies (ETGs) are revealing the second-order complexity of these objects, which have been long considered uniform, dispersion-supported spheroidals. 'Fine structure' features (e.g. ripples, plumes, tidal tails, rings) as well as depleted stellar cores (i.e. central light deficits) characterize a number of massive ETG galaxies, and can be interpreted as the result of galaxy-galaxy interactions. We discuss how the time-scale for the evolution of cores and fine structures are comparable, and hence it is expected that they develop in parallel after the major interaction event which shaped the ETG. Using archival data, we compare the 'depleted stellar mass' (i.e. the mass missing from the depleted stellar core) against the prominence of the fine structure features, and observe that they correlate inversely. This result confirms our expectation that, while the supermassive black hole (SMBH) binary (constituted by the SMBHs of the merger progenitors) excavates the core via three-body interactions, the gravitational potential of the newborn galaxy relaxes, and the fine structures fade below detection levels. We expect the inverse correlation to hold at least within the first Gyr from the merger which created the SMBH binary; after then, the fine structure evolves independently.

  1. Testing Galaxy Evolution in Unexplored Environments: the First Faint Dwarf Satellites of Local Volume LMC Analogs

    Science.gov (United States)

    Carlin, Jeffrey

    2017-08-01

    We propose to use four HST/ACS orbits to obtain follow-up imaging and resolved photometry of two candidate dwarf galaxies in the halos of Local Volume LMC analogs, which have been discovered as part of our ground-based MADCASH survey: MADCASH-1, which is a satellite of NGC 2403 (D = 3.2 Mpc), and MADCASH-2, near NGC 4214 (D = 2.9 Mpc). These are the faintest dwarf satellites known around host galaxies of Large Magellanic Cloud stellar mass outside the Local Group. We will measure accurate TRGB distances to confirm their associations with their host galaxies, derive their structural parameters, and assess their stellar populations. These two dwarf galaxies, the first of their kind around LMC analogs, are vital probes of dwarf evolution in different environments. Both of these MADCASH dwarfs are at luminosities intermediate between the classical Milky Way dwarf galaxies and the ultra-faint dwarfs. The proposed observations will resolve individual stars in these systems of small angular size, allowing us to quantify the relative presence of ancient stellar populations and younger, more metal-enriched stars, and to measure their physical properties. We will compare these to the Milky Way classical and ultra-faint dwarfs to place these systems in a broader context and assess similarities or differences between these dwarfs around dwarfs and Local Group satellites.

  2. The unorthodox evolution of major merger remnants into star-forming spiral galaxies

    Science.gov (United States)

    Sparre, Martin; Springel, Volker

    2017-10-01

    Galaxy mergers are believed to play a key role in transforming star-forming disc galaxies into quenched ellipticals. Most of our theoretical knowledge about such morphological transformations does, however, rely on idealized simulations where processes such as cooling of hot halo gas into the disc and gas accretion in the post-merger phase are not treated in a self-consistent cosmological fashion. In this paper, we study the morphological evolution of the stellar components of four major mergers occurring at z = 0.5 in cosmological hydrodynamical zoom simulations. In all simulations, the merger reduces the disc mass fraction, but all galaxies simulated at our highest resolution regrow a significant disc by z = 0 (with a disc fraction larger than 24 per cent). For runs with our default physics model, which includes galactic winds from star formation and black hole feedback, none of the merger remnants are quenched, but in a set of simulations with stronger black hole feedback, we find that major mergers can indeed quench galaxies. We conclude that major merger remnants commonly evolve into star-forming disc galaxies, unless sufficiently strong active galactic nucleus feedback assists in the quenching of the remnant.

  3. Short-term dynamical evolution of grand-design spirals in barred galaxies

    Science.gov (United States)

    Baba, Junichi

    2015-12-01

    We investigate the short-term dynamical evolution of stellar grand-design spiral arms in barred spiral galaxiesusing a three-dimensional (3D) N-body/hydrodynamic simulation. Similar to previous numerical simulations of unbarred, multiple-arm spirals, we find that grand-design spiral arms in barred galaxies are not stationary, but rather dynamic. This means that the amplitudes, pitch angles, and rotational frequencies of the spiral arms are not constant, but change within a few hundred million years (i.e. the typical rotational period of a galaxy). We also find that the clear grand-design spirals in barred galaxies appear only when the spirals connect with the ends of the bar. Furthermore, we find that the short-term behaviour of spiral arms in the outer regions (R > 1.5-2 bar radius) can be explained by the swing amplification theory and that the effects of the bar are not negligible in the inner regions (R bar radius). These results suggest that although grand-design spiral arms in barred galaxies are affected by the stellar bar, the grand-design spiral arms essentially originate not as bar-driven stationary density waves, but rather as self-excited dynamic patterns. We imply that a rigidly rotating grand-design spiral could not be a reasonable dynamical model for investigating gas flows and cloud formation even in barred spiral galaxies.

  4. VizieR Online Data Catalog: VANDELS High-Redshift Galaxy Evolution (McLure+, 2017)

    Science.gov (United States)

    McLure, R.; Pentericci, L.; Vandels Team

    2017-11-01

    This is the first data release (DR1) of the VANDELS survey, an ESO public spectroscopy survey targeting the high-redshift Universe. The VANDELS survey uses the VIMOS spectrograph on ESO's VLT to obtain ultra-deep, medium resolution, optical spectra of galaxies within the UKIDSS Ultra Deep Survey (UDS) and Chandra Deep Field South (CDFS) survey fields (0.2 sq. degree total area). Using robust photometric redshift pre-selection, VANDELS is targeting ~2100 galaxies in the redshift interval 1.0=3. In addition, VANDELS is targeting a substantial number of passive galaxies in the redshift interval 1.0survey is obtaining ultra-deep optical spectroscopy with the VIMOS MR grism and GG475 order-sorting filter, which covers the wavelength range 4800-10000Å at a dispersion of 2.5Å/pix and a spectral resolution of R~600. Each galaxy receives between a minimum of 20-hours and a maximum of 80-hours of on-source integration time. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extra-galactic survey fields with superb multi-wavelength imaging data, VANDELS is designed to produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution. (2 data files).

  5. A subgradient approach for constrained binary optimization via quantum adiabatic evolution

    Science.gov (United States)

    Karimi, Sahar; Ronagh, Pooya

    2017-08-01

    Outer approximation method has been proposed for solving the Lagrangian dual of a constrained binary quadratic programming problem via quantum adiabatic evolution in the literature. This should be an efficient prescription for solving the Lagrangian dual problem in the presence of an ideally noise-free quantum adiabatic system. However, current implementations of quantum annealing systems demand methods that are efficient at handling possible sources of noise. In this paper, we consider a subgradient method for finding an optimal primal-dual pair for the Lagrangian dual of a constrained binary polynomial programming problem. We then study the quadratic stable set (QSS) problem as a case study. We see that this method applied to the QSS problem can be viewed as an instance-dependent penalty-term approach that avoids large penalty coefficients. Finally, we report our experimental results of using the D-Wave 2X quantum annealer and conclude that our approach helps this quantum processor to succeed more often in solving these problems compared to the usual penalty-term approaches.

  6. The GOODS-MUSIC Sample: Evolution of the Luminosity Function of Red and Blue Galaxies

    Science.gov (United States)

    Salimbeni, S.; Giallongo, E.; Grazian, A.

    2007-12-01

    Using data from the GOODS public survey we analysed the galaxy properties in terms of the colour and specific star formation rate (SSFR) distributions. More specifically we analysed the galaxy bimodal distribution up to relatively high redshift (z ≃q 3). We used these properties to separate the galaxy sample in two populations (red-blue using colour; early-late using SSFR). We have then studied the evolution of the red/early and blue/late luminosity function (LF) and of the luminosity density. For the blue galaxies we find a luminosity evolution with a brightening of M^* in the z=0.2-1 interval and at higher redshift a constant LF. For the red sample, we find at the bright-end of the LF a constant density in the range 0.2-0.67 and a density reduction by a factor 5 up to redshift 3.5. For the red population we also find a characteristic shape for the LF, with a minimum around M_B(AB)=-18 and with a turn up at fainter magnitude. This shape has been represented by a double Schechter function.

  7. 3D MHD simulations of magnetic field evolution and radio polarization of barred galaxies

    Science.gov (United States)

    Kulesza-Żydzik, B.; Kulpa-Dybeł, K.; Otmianowska-Mazur, K.; Soida, M.; Urbanik, M.

    2010-11-01

    Aims: We study numerically the large-scale gas and magnetic field evolution of barred galaxies in the gravitational potential of a disk, bulge, halo, and bar. We solve non-linear MHD equations including the back-reaction of the magnetic field to the gas. We do not take into account any dynamo process. Methods: We apply the numerical MHD code to calculate the model of the galaxy in three dimensions. We construct realistic maps of high-frequency (Faraday rotation free) polarized radio emission on the basis of the simulated magnetic fields. The polarization model includes the effects of projection and limited resolution. Results: The main result is that our modeled polarization maps resemble the radio polarization structures observed in barred galaxies. The modeled polarization B-vectors distribution along the bar and between spiral arms resembles the observed topology of the magnetic field in barred galaxies. Our calculations for several different rotational velocities and sound speeds give the same result we got in our previous earlier published model. The reason of this behaviour is the dynamical evolution of the bar that causes gas to form spiral waves going radially outward. A gaseous spiral arms in turn generates magnetic ones, which live much longer in the inter-arm disk space than the gaseous pattern.

  8. The MUSIC of Galaxy Clusters - III. Properties, evolution and Y-M scaling relation of protoclusters of galaxies

    Science.gov (United States)

    Sembolini, Federico; De Petris, Marco; Yepes, Gustavo; Foschi, Emma; Lamagna, Luca; Gottlöber, Stefan

    2014-06-01

    In this work, we study the properties of protoclusters of galaxies by employing the MultiDark SImulations of galaxy Clusters (MUSIC) set of hydrodynamical simulations, featuring a sample of 282 resimulated clusters with available merger trees up to z = 4. We study the characteristics and redshift evolution of the mass and the spatial distribution for all the protoclusters, which we define as the most massive progenitors of the clusters identified at z = 0. We extend the study of the baryon content to redshifts larger than 1 also in terms of gas and stars budgets: no remarkable variations with redshift are discovered. Furthermore, motivated by the proven potential of Sunyaev-Zel'dovich surveys to blindly search for faint distant objects, we compute the scaling relation between total object mass and integrated Compton y-parameter. We find that the slope of this scaling law is steeper than what expected for a self-similarity assumption among these objects, and it increases with redshift mainly when radiative processes are included. We use three different criteria to account for the dynamical state of the protoclusters, and find no significant dependence of the scaling parameters on the level of relaxation. We exclude the dynamical state as the cause of the observed deviations from self-similarity in protoclusters.

  9. Inhomogeneous Chemical Evolution of the Galaxy in the Solar ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy; Volume 34; Issue 4. Inhomogeneous Chemical Evolution of the ... A complex chemical evolutionary history is inferred that registers episodes of time-dependent contributions from SN II+Ib/c with respect to SN Ia. It was observed that heterogeneities can remerge even ...

  10. Inhomogeneous Chemical Evolution of the Galaxy in the Solar ...

    Indian Academy of Sciences (India)

    Abstract. N-body numerical simulations of an inhomogeneous Galac- tic Chemical Evolution (GCE) of the solar neighbourhood with a high temporal resolution are presented. The solar annular ring is divided into distinct spatial grids of area ∼1–2 kpc2. Each grid evolves distinctly in terms of star formation and ...

  11. Star cluster evolution in dark matter dominated galaxies

    NARCIS (Netherlands)

    Praagman, Anneke; Hurley, Jarrod; Power, Chris

    We investigate the influence of the external tidal field of a dark matter halo on the dynamical evolution of star clusters using direct N-body simulations, where we assume that the halo is described by a Navarro, Frenk and White mass profile which has an inner density cusp. We assess how varying the

  12. Revisiting the monster: the mass profile of the galaxy cluster Abell 3827 using dynamical and strong lensing constrains

    Science.gov (United States)

    Rodrigo Carrasco Damele, Eleazar; Verdugo, Tomas

    2018-01-01

    The galaxy cluster Abell 3827 is one of the most massive clusters know at z ≦ 0.1 (Richness class 2, BM typeI, X-ray LX = 2.4 x 1044 erg s-1). The Brightest Cluster Galaxy (BCG) in Abell 3827 is perhaps the most extreme example of ongoing galaxy cannibalism. The multi-component BCG hosts the stellar remnants nuclei of at least four bright elliptical galaxies embedded in a common assymetric halo extended up to 15 kpc. The most notorious characteristic of the BCG is the existence of a unique strong gravitational lens system located within the inner 15 kpc region. A mass estimation of the galaxy based on strong lensing model was presented in Carrasco et al (2010, ApJL, 715, 160). Moreover, the exceptional strong lensing lens system in Abell 3827 and the location of the four bright galaxies has been used to measure for the first time small physical separations between dark and ordinary matter (Williams et al. 2011, MNRAS, 415, 448, Massey et al. 2015, MNRAS, 449, 3393). In this contribution, we present a detailed strong lensing and dynamical analysis of the cluster Abell 3827 based on spectroscopic redshift of the lensed features and from ~70 spectroscopically confirmed member galaxies inside 0.5 x 0.5 Mpc from the cluster center.

  13. Inferring the photometric and size evolution of galaxies from image simulations. I. Method

    Science.gov (United States)

    Carassou, Sébastien; de Lapparent, Valérie; Bertin, Emmanuel; Le Borgne, Damien

    2017-09-01

    Context. Current constraints on models of galaxy evolution rely on morphometric catalogs extracted from multi-band photometric surveys. However, these catalogs are altered by selection effects that are difficult to model, that correlate in non trivial ways, and that can lead to contradictory predictions if not taken into account carefully. Aims: To address this issue, we have developed a new approach combining parametric Bayesian indirect likelihood (pBIL) techniques and empirical modeling with realistic image simulations that reproduce a large fraction of these selection effects. This allows us to perform a direct comparison between observed and simulated images and to infer robust constraints on model parameters. Methods: We use a semi-empirical forward model to generate a distribution of mock galaxies from a set of physical parameters. These galaxies are passed through an image simulator reproducing the instrumental characteristics of any survey and are then extracted in the same way as the observed data. The discrepancy between the simulated and observed data is quantified, and minimized with a custom sampling process based on adaptive Markov chain Monte Carlo methods. Results: Using synthetic data matching most of the properties of a Canada-France-Hawaii Telescope Legacy Survey Deep field, we demonstrate the robustness and internal consistency of our approach by inferring the parameters governing the size and luminosity functions and their evolutions for different realistic populations of galaxies. We also compare the results of our approach with those obtained from the classical spectral energy distribution fitting and photometric redshift approach. Conclusions: Our pipeline infers efficiently the luminosity and size distribution and evolution parameters with a very limited number of observables (three photometric bands). When compared to SED fitting based on the same set of observables, our method yields results that are more accurate and free from

  14. SPHEREx: Understanding the Origin and Evolution of Galaxies Through the Extragalactic Background Light

    Science.gov (United States)

    Zemcov, Michael; SPHEREx Science Team

    2018-01-01

    The near IR extragalactic background light (EBL) encodes the integrated light production over cosmic history, so traces the total emission from all galaxies along the line of sight up to the ancient first-light objects responsible for the epoch of reionization (EOR). The EBL can be constrained through measurements of anisotropies, taking advantage of the fact that extragalactic populations produce fluctuations with distinct spatial and spectral characteristics from local foregrounds. In particular, EBL anisotropies trace the underlying clustering of faint emission sources, such as stars, galaxies and accreting black holes present during the EOR, dwarf galaxies, and intra-halo light (IHL), all of which are components not readily detected in point source surveys. The fluctuation amplitude observed independently by a number of recent measurements exceeds that expected from the large-scale clustering of known galaxy populations, indicating the presence of a large integrated brightness from these faint and diffuse components. Improved large-area measurements covering the entire near-IR are required to constrain the possible models for the history of emission from stars back to the EOR.SPHEREx brings new capabilities to EBL fluctuation measurements, employing 96 spectral channels covering 0.75 to 5 microns with spectral resolving power R = 41 to 135 that enable SPHEREx to carry out a multi-frequency separation of the integrated light from galaxies, IHL, and EOR components using the rich auto- and cross-correlation information available from two 45 square degree surveys of the ecliptic poles. SPHEREx is an ideal intensity mapping machine, and has the sensitivity to disentangle the history of light production associated with EBL fluctuations. SPHEREx will search for an EOR component its to minimum required level through component separation and spectral fitting techniques optimized for the near-IR. In addition to broad-band intensity mapping that enhances and extends the

  15. A spectroscopic sample of massive, quiescent z ∼ 2 galaxies: implications for the evolution of the mass-size relation

    Energy Technology Data Exchange (ETDEWEB)

    Krogager, J.-K.; Zirm, A. W.; Toft, S.; Man, A. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Brammer, G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21210 (United States)

    2014-12-10

    We present deep, near-infrared Hubble Space Telescope/Wide Field Camera 3 grism spectroscopy and imaging for a sample of 14 galaxies at z ≈ 2 selected from a mass-complete photometric catalog in the COSMOS field. By combining the grism observations with photometry in 30 bands, we derive accurate constraints on their redshifts, stellar masses, ages, dust extinction, and formation redshifts. We show that the slope and scatter of the z ∼ 2 mass-size relation of quiescent galaxies is consistent with the local relation, and confirm previous findings that the sizes for a given mass are smaller by a factor of two to three. Finally, we show that the observed evolution of the mass-size relation of quiescent galaxies between z = 2 and 0 can be explained by the quenching of increasingly larger star forming galaxies at a rate dictated by the increase in the number density of quiescent galaxies with decreasing redshift. However, we find that the scatter in the mass-size relation should increase in the quenching-driven scenario in contrast to what is seen in the data. This suggests that merging is not needed to explain the evolution of the median mass-size relation of massive galaxies, but may still be required to tighten its scatter, and explain the size growth of individual z = 2 galaxies quiescent galaxies.

  16. CANDELS: THE EVOLUTION OF GALAXY REST-FRAME ULTRAVIOLET COLORS FROM z = 8 TO 4

    Energy Technology Data Exchange (ETDEWEB)

    Finkelstein, Steven L. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Papovich, Casey; Salmon, Brett; Bassett, Robert [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Finlator, Kristian [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Ferguson, Henry C.; Koekemoer, Anton M.; Grogin, Norman A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Giavalisco, Mauro [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Reddy, Naveen A.; Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Conselice, Christopher J. [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom); Dunlop, James S.; McLure, Ross J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh (United Kingdom); Faber, S. M.; Kocevski, Dale D.; Lai, Kamson [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Hathi, Nimish P. [Carnegie Observatories, Pasadena, CA 91101 (United States); Lee, Kyoung-Soo, E-mail: stevenf@astro.as.utexas.edu [Yale Center for Astronomy and Astrophysics, Departments of Physics and Astronomy, Yale University, New Haven, CT 06520 (United States); and others

    2012-09-10

    We study the evolution of galaxy rest-frame ultraviolet (UV) colors in the epoch 4 {approx}< z {approx}< 8. We use new wide-field near-infrared data in the Great Observatories Origins Deep Survey-South field from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, Hubble Ultra Deep Field (HUDF) 2009, and Early Release Science programs to select galaxies via photometric redshift measurements. Our sample consists of 2812 candidate galaxies at z {approx}> 3.5, including 113 at z {approx_equal} 7-8. We fit the observed spectral energy distribution to a suite of synthetic stellar population models and measure the value of the UV spectral slope ({beta}) from the best-fit model spectrum. We run simulations to show that this measurement technique results in a smaller scatter on {beta} than other methods, as well as a reduced number of galaxies with catastrophically incorrect {beta} measurements (i.e., {Delta}{beta} > 1). We find that the median value of {beta} evolves significantly from -1.82{sup +0.00}{sub -0.04} at z = 4 to -2.37{sup +0.26}{sub -0.06} at z = 7. Additionally, we find that faint galaxies at z = 7 have {beta} -2.68{sup +0.39}{sub -0.24} ({approx} -2.4 after correcting for observational bias); this is redder than previous claims in the literature and does not require 'exotic' stellar populations (e.g., very low metallicities or top-heavy initial mass functions) to explain their colors. This evolution can be explained by an increase in dust extinction, from low amounts at z = 7 to A{sub V} {approx} 0.5 mag at z = 4. The timescale for this increase is consistent with low-mass asymptotic giant branch stars forming the bulk of the dust. We find no significant (<2{sigma}) correlation between {beta} and M{sub UV} when measuring M{sub UV} at a consistent rest-frame wavelength of 1500 A. This is particularly true at bright magnitudes, though our results do show evidence for a weak correlation at faint magnitudes when galaxies in the HUDF

  17. Stability-activity tradeoffs constrain the adaptive evolution of RubisCO.

    Science.gov (United States)

    Studer, Romain A; Christin, Pascal-Antoine; Williams, Mark A; Orengo, Christine A

    2014-02-11

    A well-known case of evolutionary adaptation is that of ribulose-1,5-bisphosphate carboxylase (RubisCO), the enzyme responsible for fixation of CO2 during photosynthesis. Although the majority of plants use the ancestral C3 photosynthetic pathway, many flowering plants have evolved a derived pathway named C4 photosynthesis. The latter concentrates CO2, and C4 RubisCOs consequently have lower specificity for, and faster turnover of, CO2. The C4 forms result from convergent evolution in multiple clades, with substitutions at a small number of sites under positive selection. To understand the physical constraints on these evolutionary changes, we reconstructed in silico ancestral sequences and 3D structures of RubisCO from a large group of related C3 and C4 species. We were able to precisely track their past evolutionary trajectories, identify mutations on each branch of the phylogeny, and evaluate their stability effect. We show that RubisCO evolution has been constrained by stability-activity tradeoffs similar in character to those previously identified in laboratory-based experiments. The C4 properties require a subset of several ancestral destabilizing mutations, which from their location in the structure are inferred to mainly be involved in enhancing conformational flexibility of the open-closed transition in the catalytic cycle. These mutations are near, but not in, the active site or at intersubunit interfaces. The C3 to C4 transition is preceded by a sustained period in which stability of the enzyme is increased, creating the capacity to accept the functionally necessary destabilizing mutations, and is immediately followed by compensatory mutations that restore global stability.

  18. The Origin and Evolution of the Galaxy Star Formation Rate-Stellar Mass Correlation

    Science.gov (United States)

    Gawiser, Eric; Iyer, Kartheik

    2018-01-01

    The existence of a tight correlation between galaxies’ star formation rates and stellar masses is far more surprising than usually noted. However, a simple analytical calculation illustrates that the evolution of the normalization of this correlation is driven primarily by the inverse age of the universe, and that the underlying correlation is one between galaxies’ instantaneous star formation rates and their average star formation rates since the Big Bang.Our new Dense Basis method of SED fitting (Iyer & Gawiser 2017, ApJ 838, 127) allows star formation histories (SFHs) to be reconstructed, along with uncertainties, for >10,000 galaxies in the CANDELS and 3D-HST catalogs at 0.5galaxy formation.

  19. THE SIZE EVOLUTION OF PASSIVE GALAXIES: OBSERVATIONS FROM THE WIDE-FIELD CAMERA 3 EARLY RELEASE SCIENCE PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R. E. Jr. [Physics Department, University of California, Davis, CA 95616 (United States); McCarthy, P. J. [Observatories of the Carnegie Institute of Washington, Pasadena, CA 91101 (United States); Cohen, S. H.; Rutkowski, M. J.; Mechtley, M. R.; Windhorst, R. A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Yan, H. [Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Hathi, N. P. [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Koekemoer, A. M.; Bond, H. E.; Bushouse, H. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); O' Connell, R. W. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Calzetti, D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Crockett, R. M. [Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Disney, M. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Dopita, M. A. [Research School of Astronomy and Astrophysics, The Australian National University, Weston Creek, ACT 2611 (Australia); Frogel, J. A. [Galaxies Unlimited, Lutherville, MD 21093 (United States); Hall, D. N. B. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Holtzman, J. A., E-mail: rryan@physics.ucdavis.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); and others

    2012-04-10

    We present the size evolution of passively evolving galaxies at z {approx} 2 identified in Wide-Field Camera 3 imaging from the Early Release Science program. Our sample was constructed using an analog to the passive BzK galaxy selection criterion, which isolates galaxies with little or no ongoing star formation at z {approx}> 1.5. We identify 30 galaxies in {approx}40 arcmin{sup 2} to H < 25 mag. By fitting the 10-band Hubble Space Telescope photometry from 0.22 {mu}m {approx}< {lambda}{sub obs} {approx}< 1.6 {mu}m with stellar population synthesis models, we simultaneously determine photometric redshift, stellar mass, and a bevy of other population parameters. Based on the six galaxies with published spectroscopic redshifts, we estimate a typical redshift uncertainty of {approx}0.033(1 + z). We determine effective radii from Sersic profile fits to the H-band image using an empirical point-spread function. By supplementing our data with published samples, we propose a mass-dependent size evolution model for passively evolving galaxies, where the most massive galaxies (M{sub *} {approx} 10{sup 11} M{sub Sun }) undergo the strongest evolution from z {approx} 2 to the present. Parameterizing the size evolution as (1 + z){sup -{alpha}}, we find a tentative scaling of {alpha} Almost-Equal-To (- 0.6 {+-} 0.7) + (0.9 {+-} 0.4)log (M{sub *}/10{sup 9} M{sub Sun }), where the relatively large uncertainties reflect the poor sampling in stellar mass due to the low numbers of high-redshift systems. We discuss the implications of this result for the redshift evolution of the M{sub *}-R{sub e} relation for red galaxies.

  20. Limited oxygen availability in utero may constrain the evolution of live birth in reptiles.

    Science.gov (United States)

    Rafferty, Anthony R; Evans, Roger G; Scheelings, T Franciscus; Reina, Richard D

    2013-02-01

    Although viviparity (live birth) has evolved from oviparity (egg laying) at least 140 times in vertebrates, nearly 120 of these independent events occurred within a single reptile taxon. Surprisingly, only squamate reptiles (lizards and snakes) are capable of facilitating embryonic development to increasingly advanced stages inside the mother during extended periods of oviducal egg retention. Viviparity has never evolved in turtle lineages, presumably because embryos enter and remain in an arrested state until after eggs are laid, regardless of the duration of egg retention. Until now, the limiting factor that initiates and maintains developmental arrest has remained elusive. Here, we show that oviducal hypoxia arrests embryonic development. We demonstrate that hypoxia can maintain developmental arrest after oviposition and that subsequent exposure of arrested embryos to normoxia triggers resumption of their development. We discovered remarkably low oxygen partial pressure in the oviducts of gravid turtles and found that secretions produced by the oviduct retard oxygen diffusion. Our results suggest that an extremely hypoxic environment in the oviduct arrests embryonic development and may constrain the evolution of viviparity in turtles, with the reduced diffusive capacity of oviducal secretions possibly creating or contributing to this hypoxia. We anticipate that these findings will allow us to better understand the mechanisms underlying the evolutionary transition between reproductive modes.

  1. Dual-TRACER: High resolution fMRI with constrained evolution reconstruction.

    Science.gov (United States)

    Li, Xuesong; Ma, Xiaodong; Li, Lyu; Zhang, Zhe; Zhang, Xue; Tong, Yan; Wang, Lihong; Sen Song; Guo, Hua

    2017-03-02

    fMRI with high spatial resolution is beneficial for studies in psychology and neuroscience, but is limited by various factors such as prolonged imaging time, low signal to noise ratio and scarcity of advanced facilities. Compressed Sensing (CS) based methods for accelerating fMRI data acquisition are promising. Other advanced algorithms like k-t FOCUSS or PICCS have been developed to improve performance. This study aims to investigate a new method, Dual-TRACER, based on Temporal Resolution Acceleration with Constrained Evolution Reconstruction (TRACER), for accelerating fMRI acquisitions using golden angle variable density spiral. Both numerical simulations and in vivo experiments at 3T were conducted to evaluate and characterize this method. Results show that Dual-TRACER can provide functional images with a high spatial resolution (1×1mm(2)) under an acceleration factor of 20 while maintaining hemodynamic signals well. Compared with other investigated methods, dual-TRACER provides a better signal recovery, higher fMRI sensitivity and more reliable activation detection. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. A WISE Survey of Star Formation in the Milky Way: New Insight into Galaxy Evolution

    Science.gov (United States)

    Koenig, Xavier

    We propose to measure the recent star formation rate (SFR) in the Perseus Arm of the Milky Way galaxy and its relation to the surface density of gas, whether molecular or atomic on a range of scales from star forming clusters through large star forming complexes to the full scale of the Galactic Arm. We will test the connection between the SFR-gas relationship in the Galaxy and comparable measurements made in external galaxies in order to probe its origin and better understand the role and contribution of star formation to cosmological galaxy evolution. We also propose to study star formation that has been triggered by the recent formation of massive star clusters in order to discern the mechanisms of triggering that may be operating on super bubble size scales of more than 100 parsecs. This study will allow us to understand one of the key factors that sets the efficiency with which gas becomes stars as galaxies evolve with time. In order to achieve these goals, we will carry out a census of young stellar objects in the outer Milky Way Perseus Arm, using data gathered by the WISE and 2MASS all-sky surveys, with additional use of archival data from the Spitzer Space Telescope. We will develop and refine a young star finding algorithm that uses WISE and 2MASS photometry to identify and classify young stars and filters out contaminating objects such as background galaxies. We will measure the gas content with extinction maps made with data from 2MASS. We will test the triggered star formation models by analyzing the spatial distributions of young stars in super-bubbles and massive star forming regions in the Perseus Arm. This study will produce a key, like-for-like comparison between the extragalactic star formation rate-molecular gas relation and the Galactic relation and will advance the progress in linking Galactic and extragalactic studies of star formation, studying massive star forming regions that are representative of the major mode of star formation. The

  3. Measuring the Evolution of Stellar Populations And Gas Metallicity in Galaxies with Far-Infrared Space Spectroscopy

    Science.gov (United States)

    Stacey, Gordon

    We propose a study of the evolution of stellar populations and gas metallicities in about 80 nearby star forming galaxies based on mining the NASA data archives for observations of the [NIII] 57 µm, [OIII] 52 µm and/or 88 µm, [NII] 122 and [CII] 158 µm far-infrared (FIR) fine- structure lines and other archives for thermal radio continuum. These lines are powerful probes of both stellar populations and gas properties and our primary science derives from these tracers. For sources that show both signs of active galactic nuclei (AGN) and star formation, we will take advantage of the readily available NASA Spitzer IRS data base that includes mid-IR [NeII] 12.8 µm, [NeIII] 15.6 µm and [NeV] 14.3 µm, [OIV] 25.9 µm and PAH observations. These complementary data reveal the relative fractions of the FIR line emission that might arise from star formation and the narrow line regions (NLR) associated with an AGN, thereby providing a robust set of observations to compare with star formation models. Subsets of the FIR lines have been detected from hundreds of nearby galaxies. From both theoretical studies and the results of these pioneering observations we know that these lines can be powerful probes of stellar populations and star formation in galaxies. Here we plan to use various combinations of the lines to constrain (1) the age of the stellar populations (through lines that trace the hardness of the stellar radiation fields, hence stellar spectral type), (2) the degree of processing of the interstellar medium (through lines that trace growth of secondary to primary element abundances for example, the N/O ratio), (3) the efficiency of star formation (through growth in absolute abundances of N and O, the N/H and O/H ratios), and (4) the current day mass function of upper main sequence stars. Surprisingly, there has been no systematic study of the large sample of these line detections made with PACS on Herschel in order to truly assess and calibrate their diagnostic

  4. Probing Structure Formation Physics with the Evolution of Galaxy Cluster Properties

    Science.gov (United States)

    Burke, Douglas J.; Arnaud, M.; Boehringer, H.; Borgani, S.; Collins, C.; Mullis, C.; Nichol, R.; Pointecouteau, E.; Pratt, G.; Romer, K.; Sabirli, S.; Viana, P.; Vikhlihnin, A.; Voit, M.

    2006-12-01

    XMM-Newton and Chandra observations show that the dark-matter profile of local galaxy clusters is universal, with a central cusp, as predicted by numerical simulations. In contrast, the physics governing the baryonic component remains far from being understood: the gas properties of local clusters do scale self-similarly down to low masses (around 2 keV), but the scaling laws differ from the simplest expectations. It appears that the gas history depends not only on gravitational effects but also on the interplay between cooling and various galaxy feedback mechanisms, none of which are well understood. Recent evolution studies confirm that clusters follow scaling laws up to high redshifts, but the amount of evolution remains uncertain. We were awarded a XMM-Newton Large Programme in AO4 to assess the evolution of the structural and scaling properties of an unbiased sample of 23 clusters at a redshift of 0.5, covering a large mass range (2.5 to 12 keV). In this contribution we describe the initial results of the full sample and compare the cluster properties to local samples. We acknowledge support from NASA grant NNG0-5GL94G and NASA Contract NAS8-39073.

  5. Mass and Environment as Drivers of Galaxy Evolution in SDSS and zCOSMOS and the Origin of the Schechter Function

    Science.gov (United States)

    Peng, Ying-jie; Lilly, Simon J.; Kovač, Katarina; Bolzonella, Micol; Pozzetti, Lucia; Renzini, Alvio; Zamorani, Gianni; Ilbert, Olivier; Knobel, Christian; Iovino, Angela; Maier, Christian; Cucciati, Olga; Tasca, Lidia; Carollo, C. Marcella; Silverman, John; Kampczyk, Pawel; de Ravel, Loic; Sanders, David; Scoville, Nicholas; Contini, Thierry; Mainieri, Vincenzo; Scodeggio, Marco; Kneib, Jean-Paul; Le Fèvre, Olivier; Bardelli, Sandro; Bongiorno, Angela; Caputi, Karina; Coppa, Graziano; de la Torre, Sylvain; Franzetti, Paolo; Garilli, Bianca; Lamareille, Fabrice; Le Borgne, Jean-Francois; Le Brun, Vincent; Mignoli, Marco; Perez Montero, Enrique; Pello, Roser; Ricciardelli, Elena; Tanaka, Masayuki; Tresse, Laurence; Vergani, Daniela; Welikala, Niraj; Zucca, Elena; Oesch, Pascal; Abbas, Ummi; Barnes, Luke; Bordoloi, Rongmon; Bottini, Dario; Cappi, Alberto; Cassata, Paolo; Cimatti, Andrea; Fumana, Marco; Hasinger, Gunther; Koekemoer, Anton; Leauthaud, Alexei; Maccagni, Dario; Marinoni, Christian; McCracken, Henry; Memeo, Pierdomenico; Meneux, Baptiste; Nair, Preethi; Porciani, Cristiano; Presotto, Valentina; Scaramella, Roberto

    2010-09-01

    We explore the simple inter-relationships between mass, star formation rate, and environment in the SDSS, zCOSMOS, and other deep surveys. We take a purely empirical approach in identifying those features of galaxy evolution that are demanded by the data and then explore the analytic consequences of these. We show that the differential effects of mass and environment are completely separable to z ~ 1, leading to the idea of two distinct processes of "mass quenching" and "environment quenching." The effect of environment quenching, at fixed over-density, evidently does not change with epoch to z ~ 1 in zCOSMOS, suggesting that the environment quenching occurs as large-scale structure develops in the universe, probably through the cessation of star formation in 30%-70% of satellite galaxies. In contrast, mass quenching appears to be a more dynamic process, governed by a quenching rate. We show that the observed constancy of the Schechter M* and αs for star-forming galaxies demands that the quenching of galaxies around and above M* must follow a rate that is statistically proportional to their star formation rates (or closely mimic such a dependence). We then postulate that this simple mass-quenching law in fact holds over a much broader range of stellar mass (2 dex) and cosmic time. We show that the combination of these two quenching processes, plus some additional quenching due to merging naturally produces (1) a quasi-static single Schechter mass function for star-forming galaxies with an exponential cutoff at a value M* that is set uniquely by the constant of proportionality between the star formation and mass quenching rates and (2) a double Schechter function for passive galaxies with two components. The dominant component (at high masses) is produced by mass quenching and has exactly the same M* as the star-forming galaxies but a faint end slope that differs by Δαs ~ 1. The other component is produced by environment effects and has the same M* and αs as the

  6. TRACING THE EVOLUTION OF HIGH-REDSHIFT GALAXIES USING STELLAR ABUNDANCES

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, Brian D.; O’Shea, Brian W. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Beers, Timothy C. [Department of Physics and JINA—Center for the Evolution of the Elements, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Tumlinson, Jason, E-mail: crosby.bd@gmail.com [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2016-03-20

    This paper presents the first results from a model for chemical evolution that can be applied to N-body cosmological simulations and quantitatively compared to measured stellar abundances from large astronomical surveys. This model convolves the chemical yield sets from a range of stellar nucleosynthesis calculations (including asymptotic giant branch stars, Type Ia and II supernovae, and stellar wind models) with a user-specified stellar initial mass function (IMF) and metallicity to calculate the time-dependent chemical evolution model for a “simple stellar population” (SSP) of uniform metallicity and formation time. These SSP models are combined with a semianalytic model for galaxy formation and evolution that uses merger trees from N-body cosmological simulations to track several α- and iron-peak elements for the stellar and multiphase interstellar medium components of several thousand galaxies in the early (z ≥ 6) universe. The simulated galaxy population is then quantitatively compared to two complementary data sets of abundances in the Milky Way stellar halo and is capable of reproducing many of the observed abundance trends. The observed abundance ratio distributions are best reproduced with a Chabrier IMF, a chemically enriched star formation efficiency of 0.2, and a redshift of reionization of 7. Many abundances are qualitatively well matched by our model, but our model consistently overpredicts the carbon-enhanced fraction of stars at low metallicities, likely owing to incomplete coverage of Population III stellar yields and supernova models and the lack of dust as a component of our model.

  7. Radio galaxies radiation transfer, dynamics, stability and evolution of a synchrotron plasmon

    CERN Document Server

    Pacholczyk, A G

    1977-01-01

    Radio Galaxies: Radiation Transfer, Dynamics, Stability and Evolution of a Synchrotron Plasmon deals with the physics of a region in space containing magnetic field and thermal and relativistic particles (a plasmon). The synchrotron emission and absorption of this region are discussed, along with the properties of its spectrum; its linear and circular polarization; transfer of radiation through such a region; its dynamics and expansion; and interaction with external medium.Comprised of eight chapters, this volume explores the stability, turbulence, and acceleration of particles in a synchrotro

  8. Co-evolution of Massive Black Holes and Their Host Galaxies

    Science.gov (United States)

    Chen, Y. M.

    2010-07-01

    A scenario of co-evolution of supermassive black holes (SMBHs) and galaxies has been clearly conducted by the important evidence from observational results of quasar host galaxies and the relation between spheroid and SMBH mass. There are a plenty of unresolved problems and questions, some being basic, to be addressed in this scenario. The main goal of the present thesis is focusing on the mysterious scenario including growth of primordial black holes, cosmological evolution of spins and duty cycle of SMBHs, and interaction between the SMBH activity and star formation in galaxies from low to high redshifts. We review the main progress of this field over the past decade since the discovery of Magorrian relation and present comments on some questions in light of our view of points. The key questions to be addressed in this thesis work are: (1) how does the fast growth of primordial black holes influence their evolution? (2) what is the equation to describe the co-evolution of SMBHs and galaxies? (3) what is the mechanism to control the co-evolution? (4) how to transport the fueling gas from kpc scale to the center? It has been suggested that fast growth of primordial black holes via super-Eddington accretion is a promising way to form SMBHs in high redshift universe. Neutrino cooling has been employed and expedites the growth. We consider the Compton heating of the surroundings of the primordial black holes. We find that the realistic accretion rate is only a few percent of the Eddington rate, and the accretion is episodic. It implies that the fast growth via super-Eddington is not feasible. These conclusions have been confirmed by the detailed numerical simulations of Milosavljevic et al. (2008). The difficulties of the fast growth via accretion of baryon particles make the formation of SMBHs elusive in high redshift universe. We developed a new formulation to calculate the duty cycle of SMBHs based on the Soltan argument. We show it can be expressed by the mass

  9. PREDICTING Lyα AND Mg II FLUXES FROM K AND M DWARFS USING GALAXY EVOLUTION EXPLORER ULTRAVIOLET PHOTOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Shkolnik, Evgenya L.; Rolph, Kristina A. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Peacock, Sarah; Barman, Travis S., E-mail: shkolnik@lowell.edu, E-mail: kristina.rolph@fandm.edu, E-mail: speacock@lpl.arizona.edu, E-mail: barman@lpl.arizona.edu [Department of Planetary Sciences and Lunar and Planetary Laboratory University of Arizona, Tucson AZ 85721 (United States)

    2014-11-20

    A star's ultraviolet (UV) emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Lyα emission line at 1216 Å, which dominates the far-ultraviolet (FUV) spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Lyα, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Lyα line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Lyα and GALEX far- and near-ultraviolet (NUV) chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Lyα to the GALEX fluxes reveal how the relative strength of Lyα compared to the broadband fluxes weakens as the FUV and NUV excess flux increase. We also correlate GALEX fluxes with the strong NUV Mg II h+k spectral emission lines formed at lower chromospheric temperatures than Lyα. The reported correlations provide estimates of intrinsic Lyα and Mg II fluxes for the thousands of K and M stars in the archived GALEX all-sky surveys. These will constrain new stellar upper atmosphere models for cool stars and provide realistic inputs to models describing exoplanetary photochemistry and atmospheric evolution in the absence of UV spectroscopy.

  10. Ultrafaint dwarfs—star formation and chemical evolution in the smallest galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Webster, David; Bland-Hawthorn, Joss [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Sutherland, Ralph, E-mail: d.webster@physics.usyd.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia)

    2014-11-20

    In earlier work, we showed that a dark matter halo with a virial mass of 10{sup 7} M {sub ☉} can retain a major part of its baryons in the face of the pre-ionization phase and supernova (SN) explosion from a 25 M {sub ☉} star. Here, we expand on the results of that work, investigating the star formation and chemical evolution of the system beyond the first SN. In a galaxy with a mass M {sub vir} = 10{sup 7} M {sub ☉}, sufficient gas is retained by the potential for a second period of star formation to occur. The impact of a central explosion is found to be much stronger than that of an off-center explosion both in blowing out the gas and in enriching it, as in the off-center case most of the SN energy and metals escape into the intergalactic medium. We model the star formation and metallicity, given the assumption that stars form for 100, 200, 400, and 600 Myr, and discuss the results in the context of recent observations of very low-mass galaxies. We show that we can account for most features of the observed relationship between [α/Fe] and [Fe/H] in ultra-faint dwarf galaxies with the assumption that the systems formed at a low mass, rather than being remnants of much larger systems.

  11. Can supermassive black holes influence the evolution of their host galaxies?

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J.; Braito, V.; Veilleux, S.; Reynolds, C.; Lobban, A.

    2016-06-01

    Powerful winds driven by active galactic nuclei (AGN) are often invoked to play a fundamental role in the evolution of both supermassive black holes (SMBHs) and their host galaxies, quenching star formation and explaining the tight SMBH-galaxy relations. A strong support of this "quasar mode" feedback came from the recent X-ray observation of a mildly relativistic accretion disk wind in an ultraluminous infrared galaxy and its connection with a large-scale molecular outflow observed in the IR with Herschel, suggesting a direct link between the SMBH and the gas out of which stars form. Spectroscopic observations, especially in the X-ray band, suggest that such accretion disk winds may be common in local AGN and quasars. However, their origin and characteristics are still not fully understood. Detailed theoretical models and simulations focused on radiation, magnetohydrodynamic (MHD) or a combination of these two processes, to investigate the possible acceleration mechanisms and dynamics of these winds. XMM-Newton provided a fundamental contribution to these studies and it will still provide the highest effective area in the critical Fe K band of the spectrum until the launch of Athena. Very important improvements are expected from the high energy resolution of the Hitomi X-ray Observatory.

  12. Using the XMM-Newton Optical Monitor to Study Cluster Galaxy Evolution

    Science.gov (United States)

    Miller, Neal A.; O'Steen, Richard; Yen, Steffi; Kuntz, K. D.; Hammer, Derek

    2012-01-01

    We explore the application of XMM Newton Optical Monitor (XMM-OM) ultraviolet (UV) data to study galaxy evolution. Our sample is constructed as the intersection of all Abell clusters with z < 0.05 and having archival XMM-OM data in either the UVM2 or UVW1 filters, plus optical and UV photometry from the Sloan Digital Sky Survey and GALEX, respectively. The 11 resulting clusters include 726 galaxies with measured redshifts, 520 of which have redshifts placing them within their parent Abell clusters. We develop procedures for manipulating the XMM-OM images and measuring galaxy photometry from them, and we confirm our results via comparison with published catalogs. Color-magnitude diagrams (CMDs) constructed using the XMM-OM data along with SDSS optical data show promise for evolutionary studies, with good separation between red and blue sequences and real variation in the width of the red sequence that is likely indicative of differences in star formation history. This is particularly true for UVW1 data, as the relative abundance of data collected using this filter and its depth make it an attractive choice. Available tools that use stellar synthesis libraries to fit the UV and optical photometric data may also be used, thereby better describing star formation history within the past billion years and providing estimates of total stellar mass that include contributions from young stars. Finally, color-color diagrams that include XMM-OM UV data appear useful to the photometric identification of both extragalactic and stellar sources.

  13. Gas Removal in the Ursa Minor Galaxy: Linking Hydrodynamics and Chemical Evolution Models

    Energy Technology Data Exchange (ETDEWEB)

    Caproni, Anderson; Lanfranchi, Gustavo Amaral; Baio, Gabriel Henrique Campos; Kowal, Grzegorz [Núcleo de Astrofísica Teórica, Universidade Cruzeiro do Sul, R. Galvão Bueno 868, Liberdade, 01506-000, São Paulo, SP (Brazil); Falceta-Gonçalves, Diego, E-mail: anderson.caproni@cruzeirodosul.edu.br [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Rua Arlindo Bettio 1000, CEP 03828-000 São Paulo (Brazil)

    2017-04-01

    We present results from a non-cosmological, three-dimensional hydrodynamical simulation of the gas in the dwarf spheroidal galaxy Ursa Minor. Assuming an initial baryonic-to-dark-matter ratio derived from the cosmic microwave background radiation, we evolved the galactic gas distribution over 3 Gyr, taking into account the effects of the types Ia and II supernovae. For the first time, we used in our simulation the instantaneous supernovae rates derived from a chemical evolution model applied to spectroscopic observational data of Ursa Minor. We show that the amount of gas that is lost in this process is variable with time and radius, being the highest rates observed during the initial 600 Myr in our simulation. Our results indicate that types Ia and II supernovae must be essential drivers of the gas loss in Ursa Minor galaxy (and probably in other similar dwarf galaxies), but it is ultimately the combination of galactic winds powered by these supernovae and environmental effects (e.g., ram-pressure stripping) that results in the complete removal of the gas content.

  14. Active Galaxies

    DEFF Research Database (Denmark)

    Kilerci Eser, Ece

    one is related to the mass estimates of supermassive black holes (SMBHs). Mass estimates of SMBHs are important to understand the formation and evolution of SMBHs and their host galaxies. Black hole masses in Type 1 AGN are measured with the reverberation mapping (RM) technique. Reverberation mapping......Galaxy formation and evolution is one of the main research themes of modern astronomy. Active galaxies such as Active Galactic Nuclei (AGN) and Ultraluminous Infrared Galaxies (ULIRGs) are important evolutionary stages of galaxies. The ULIRG stage is mostly associated with galaxy mergers...... and interactions. During the interactions of gas-rich galaxies, the gas inflows towards the centers of the galaxies and can trigger both star formation and AGN activity. The ULIRG stage includes rapid star formation activity and fast black hole growth that is enshrouded by dust. Once the AGN emission...

  15. Constraining the inferred paleohydrologic evolution of a deep unsaturated zone in the Amargosa Desert

    Science.gov (United States)

    Walvoord, Michelle A.; Stonestrom, David A.; Andraski, Brian J.; Striegl, Robert G.

    2004-01-01

    Natural flow regimes in deep unsaturated zones of arid interfluvial environments are rarely in hydraulic equilibrium with near-surface boundary conditions imposed by present-day plant–soil–atmosphere dynamics. Nevertheless, assessments of water resources and contaminant transport require realistic estimates of gas, water, and solute fluxes under past, present, and projected conditions. Multimillennial transients that are captured in current hydraulic, chemical, and isotopic profiles can be interpreted to constrain alternative scenarios of paleohydrologic evolution following climatic and vegetational shifts from pluvial to arid conditions. However, interpreting profile data with numerical models presents formidable challenges in that boundary conditions must be prescribed throughout the entire Holocene, when we have at most a few decades of actual records. Models of profile development at the Amargosa Desert Research Site include substantial uncertainties from imperfectly known initial and boundary conditions when simulating flow and solute transport over millennial timescales. We show how multiple types of profile data, including matric potentials and porewater concentrations of Cl−, δD, δ18O, can be used in multiphase heat, flow, and transport models to expose and reduce uncertainty in paleohydrologic reconstructions. Results indicate that a dramatic shift in the near-surface water balance occurred approximately 16000 yr ago, but that transitions in precipitation, temperature, and vegetation were not necessarily synchronous. The timing of the hydraulic transition imparts the largest uncertainty to model-predicted contemporary fluxes. In contrast, the uncertainties associated with initial (late Pleistocene) conditions and boundary conditions during the Holocene impart only small uncertainties to model-predicted contemporaneous fluxes.

  16. Multi-Objective Differential Evolution for Voltage Security Constrained Optimal Power Flow in Deregulated Power Systems

    Science.gov (United States)

    Roselyn, J. Preetha; Devaraj, D.; Dash, Subhransu Sekhar

    2013-11-01

    Voltage stability is an important issue in the planning and operation of deregulated power systems. The voltage stability problems is a most challenging one for the system operators in deregulated power systems because of the intense use of transmission line capabilities and poor regulation in market environment. This article addresses the congestion management problem avoiding offline transmission capacity limits related to voltage stability by considering Voltage Security Constrained Optimal Power Flow (VSCOPF) problem in deregulated environment. This article presents the application of Multi Objective Differential Evolution (MODE) algorithm to solve the VSCOPF problem in new competitive power systems. The maximum of L-index of the load buses is taken as the indicator of voltage stability and is incorporated in the Optimal Power Flow (OPF) problem. The proposed method in hybrid power market which also gives solutions to voltage stability problems by considering the generation rescheduling cost and load shedding cost which relieves the congestion problem in deregulated environment. The buses for load shedding are selected based on the minimum eigen value of Jacobian with respect to the load shed. In the proposed approach, real power settings of generators in base case and contingency cases, generator bus voltage magnitudes, real and reactive power demands of selected load buses using sensitivity analysis are taken as the control variables and are represented as the combination of floating point numbers and integers. DE/randSF/1/bin strategy scheme of differential evolution with self-tuned parameter which employs binomial crossover and difference vector based mutation is used for the VSCOPF problem. A fuzzy based mechanism is employed to get the best compromise solution from the pareto front to aid the decision maker. The proposed VSCOPF planning model is implemented on IEEE 30-bus system, IEEE 57 bus practical system and IEEE 118 bus system. The pareto optimal

  17. Large Structures and Galaxy Evolution in COSMOS at z < 1.1

    Science.gov (United States)

    Scoville, N.; Aussel, H.; Benson, A.; Blain, A.; Calzetti, D.; Capak, P.; Ellis, R. S.; El-Zant, A.; Finoguenov, A.; Giavalisco, M.; Guzzo, L.; Hasinger, G.; Koda, J.; Le Fèvre, O.; Massey, R.; McCracken, H. J.; Mobasher, B.; Renzini, A.; Rhodes, J.; Salvato, M.; Sanders, D. B.; Sasaki, S. S.; Schinnerer, E.; Sheth, K.; Shopbell, P. L.; Taniguchi, Y.; Taylor, J. E.; Thompson, D. J.

    2007-09-01

    We present the first identification of large-scale structures (LSSs) at zpopulation-recovering structures on all scales from 1' to 20' without a priori assumptions for the structure size or density profile. The COSMOS photometric redshift catalog yields a sample of 1.5×105 galaxies with redshift accuracy, ΔzFWHM/(1+z)population age difference of ~2-4 Gyr at z=0.3-1. We also investigate the evolution of key galactic properties-mass, luminosity, SED, and star formation rate (SFR)-with redshift and environmental density as derived from overdensities in the full pseudo-3D cube. Both the maturity of the stellar populations and the ``downsizing'' of star formation in galaxies vary strongly with redshift (epoch) and environment. For a very broad mass range (1010-1012 Msolar), we find that galaxies in dense environments tend to be older; this is not just restricted to the most massive galaxies. And in low-density environments, the most massive galaxies appear to have also been formed very early (z>2), compared to the lower mass galaxies there. Over the range zpopulations. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555 also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), and the National Optical Astronomy Observatory (NOAO), which are operated by AURA, Inc. under cooperative agreement with the National Science Foundation (NSF); the National Radio Astronomy Observatory which is a facility of the NSF operated under cooperative agreement by

  18. LOCAL LUMINOUS INFRARED GALAXIES. III. CO-EVOLUTION OF BLACK HOLE GROWTH AND STAR FORMATION ACTIVITY?

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Herrero, Almudena; Hernan-Caballero, Antonio [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Pereira-Santaella, Miguel [Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, I-00133 Rome (Italy); Rieke, George H. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Diamond-Stanic, Aleksandar M. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States); Wang Yiping [National Astronomical Observatories, Chaoyang District, Beijing 100012 (China); Rigopoulou, Dimitra [Astrophysics Department, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2013-03-10

    Local luminous infrared (IR) galaxies (LIRGs) have both high star formation rates (SFR) and a high AGN (Seyfert and AGN/starburst composite) incidence. Therefore, they are ideal candidates to explore the co-evolution of black hole (BH) growth and star formation (SF) activity, not necessarily associated with major mergers. Here, we use Spitzer/IRS spectroscopy of a complete volume-limited sample of local LIRGs (distances of <78 Mpc). We estimate typical BH masses of 3 Multiplication-Sign 10{sup 7} M{sub Sun} using [Ne III] 15.56 {mu}m and optical [O III] {lambda}5007 gas velocity dispersions and literature stellar velocity dispersions. We find that in a large fraction of local LIRGs, the current SFR is taking place not only in the inner nuclear {approx}1.5 kpc region, as estimated from the nuclear 11.3 {mu}m PAH luminosities, but also in the host galaxy. We next use the ratios between the SFRs and BH accretion rates (BHAR) to study whether the SF activity and BH growth are contemporaneous in local LIRGs. On average, local LIRGs have SFR to BHAR ratios higher than those of optically selected Seyferts of similar active galactic nucleus (AGN) luminosities. However, the majority of the IR-bright galaxies in the revised-Shapley-Ames Seyfert sample behave like local LIRGs. Moreover, the AGN incidence tends to be higher in local LIRGs with the lowest SFRs. All of this suggests that in local LIRGs there is a distinct IR-bright star-forming phase taking place prior to the bulk of the current BH growth (i.e., AGN phase). The latter is reflected first as a composite and then as a Seyfert, and later as a non-LIRG optically identified Seyfert nucleus with moderate SF in its host galaxy.

  19. Reconstructing the galaxy density field with photometric redshifts - II. Environment-dependent galaxy evolution since z ≃ 3

    Science.gov (United States)

    Malavasi, Nicola; Pozzetti, Lucia; Cucciati, Olga; Bardelli, Sandro; Ilbert, Olivier; Cimatti, Andrea

    2017-09-01

    Although extensively investigated, the role of the environment in galaxy formation is still not well understood. In this context, the galaxy stellar mass function (GSMF) is a powerful tool to understand how environment relates to galaxy mass assembly and the quenching of star formation. In this work, we make use of the high-precision photometric redshifts of the UltraVISTA Survey to study the GSMF in different environments up to z ˜ 3, on physical scales from 0.3 to 2 Mpc, down to masses of M ˜ 1010 M⊙. We witness the appearance of environmental signatures for both quiescent and star-forming galaxies. We find that the shape of the GSMF of quiescent galaxies is different in high- and low-density environments up to z ˜ 2 with the high-mass end (M ≳ 1011 M⊙) being enhanced in high-density environments. On the contrary, for star-forming galaxies, a difference between the GSMF in high- and low-density environments is present for masses M ≲ 1011 M⊙. Star-forming galaxies in this mass range appear to be more frequent in low-density environments up to z 2. Our results, in terms of general trends in the shape of the GSMF, are in agreement with a scenario in which galaxies are quenched when they enter hot gas-dominated massive haloes that are preferentially in high-density environments.

  20. Differential evolution of the UV luminosity function of Lyman break galaxies from z ~ 5 to 3

    Science.gov (United States)

    Iwata, I.; Ohta, K.; Tamura, N.; Akiyama, M.; Aoki, K.; Ando, M.; Kiuchi, G.; Sawicki, M.

    2007-04-01

    We report the ultraviolet luminosity function (UVLF) of Lyman break galaxies at z ~ 5 derived from a deep and wide survey using the prime focus camera of the 8.2 m Subaru telescope (Suprime-Cam). Target fields consist of two blank regions of the sky, namely, the region including the Hubble Deep Field-North and the J0053+1234 region, and the total effective surveyed area is 1290 arcmin2. Applications of carefully determined colour selection criteria in V - Ic and Ic - z' yield a detection of 853 z ~ 5 candidates with z'AB ~ L*z=3) LBGs from that at z ~ 3, while there is a significant decline in the LF's faint end with increasing look-back time. This result means that the evolution of the number densities is differential with UV luminosity: the number density of UV luminous objects remains almost constant from z ~ 5 to 3 (the cosmic age is about 1.2 to 2.1 Gyr) while the number density of fainter objects gradually increases with cosmic time. This trend becomes apparent thanks to the small uncertainties in number densities both in the bright and faint parts of LFs at different epochs that are made possible by the deep and wide surveys we use. We discuss the origins of this differential evolution of the UVLF along the cosmic time and suggest that our observational findings are consistent with the biased galaxy evolution scenario: a galaxy population hosted by massive dark haloes starts active star formation preferentially at early cosmic time, while less massive galaxies increase their number density later. We also calculated the UV luminosity density by integrating the UVLF and at z ~ 5 found it to be 38.8+6.7-4.1 per cent of that at z ~ 3 for the luminosity range L > 0.1L*z=3. By combining our results with those from the literature, we find that the cosmic UV luminosity density marks its peak at and then slowly declines towards higher redshift. Based on data collected at Subaru Telescope and partly obtained from the SMOKA science archive at Astronomical Data Analysis

  1. Evolution of Galaxy Luminosity and Stellar-Mass Functions since $z=1$ with the Dark Energy Survey Science Verification Data

    Energy Technology Data Exchange (ETDEWEB)

    Capozzi, D.; et al.

    2017-07-27

    We present the first study of the evolution of the galaxy luminosity and stellar-mass functions (GLF and GSMF) carried out by the Dark Energy Survey (DES). We describe the COMMODORE galaxy catalogue selected from Science Verification images. This catalogue is made of $\\sim 4\\times 10^{6}$ galaxies at $0galaxy catalogues and they enable us to study the evolution of GLF and GSMF at $0galaxies build up their masses over cosmic time. We find that both the ${\\it i}$-band galaxy luminosity and stellar mass functions are characterised by a double-Schechter shape at $z<0.2$. Both functions agree well with those based on spectroscopic redshifts. The DES GSMF agrees especially with those measured for the GAlaxy Mass Assembly and the PRism MUlti-object Survey out to $z\\sim1$. At $0.2galaxies have less stellar mass, their luminosities do not change substantially because of their younger and brighter stellar populations. Finally, we also find evidence for a top-down mass-dependent evolution of the GSMF.

  2. Horizon Run 4 Simulation: Coupled Evolution of Galaxies and Large-Scale Structures of the Universe

    Science.gov (United States)

    Kim, Juhan; Park, Changbom; L'Huillier, Benjamin; Hong, Sungwook E.

    2015-08-01

    The Horizon Run 4 is a cosmological N-body simulation designed for the study of coupled evolution between galaxies and large-scale structures of the Universe, and for the test of galaxy formation models. Using 6300^3 gravitating particles in a cubic box of L_{box} = 3150 h^{-1} Mpc, we build a dense forest of halo merger trees to trace the halo merger history with a halo mass resolution scale down to M_s = 2.7 × 10^{11} h^{-1} M_⊙. We build a set of particle and halo data, which can serve as testbeds for comparison of cosmological models and gravitational theories with observations. We find that the FoF halo mass function shows a substantial deviation from the universal form with tangible redshift evolution of amplitude and shape. At higher redshifts, the amplitude of the mass function is lower, and the functional form is shifted toward larger values of ln (1/σ). We also find that the baryonic acoustic oscillation feature in the two-point correlation funct-ion of mock galaxies becomes broader with a peak position moving to smaller scales and the peak amplitude decreasing for increasing directional cosine mu compared to the linear predictions. From the halo merger trees built from halo data at 75 redshifts, we measure the half-mass epoch of halos and find that less massive halos tend to reach half of their current mass at higher redshifts. Simulation outputs including snapshot data, past lightcone space data, and halo merger data are available at http://sdss.kias.re.kr/astro/Horizon-Run4

  3. EVOLUTION OF THE MASS-METALLICITY RELATIONS IN PASSIVE AND STAR-FORMING GALAXIES FROM SPH-COSMOLOGICAL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Romeo Velona, A. D.; Gavignaud, I.; Meza, A. [Departamento de Ciencias Fisicas, Universidad Andres Bello, Av. Republica 220, Santiago (Chile); Sommer-Larsen, J. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark); Napolitano, N. R. [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Antonuccio-Delogu, V. [INAF-Osservatorio Astrofisico di Catania, v. S. Sofia 78, I-95123 Catania (Italy); Cielo, S., E-mail: aro@oact.inaf.it [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2013-06-20

    We present results from SPH-cosmological simulations, including self-consistent modeling of supernova feedback and chemical evolution, of galaxies belonging to two clusters and 12 groups. We reproduce the mass-metallicity (ZM) relation of galaxies classified in two samples according to their star-forming (SF) activity, as parameterized by their specific star formation rate (sSFR), across a redshift range up to z = 2. The overall ZM relation for the composite population evolves according to a redshift-dependent quadratic functional form that is consistent with other empirical estimates, provided that the highest mass bin of the brightest central galaxies is excluded. Its slope shows irrelevant evolution in the passive sample, being steeper in groups than in clusters. However, the subsample of high-mass passive galaxies only is characterized by a steep increase of the slope with redshift, from which it can be inferred that the bulk of the slope evolution of the ZM relation is driven by the more massive passive objects. The scatter of the passive sample is dominated by low-mass galaxies at all redshifts and keeps constant over cosmic times. The mean metallicity is highest in cluster cores and lowest in normal groups, following the same environmental sequence as that previously found in the red sequence building. The ZM relation for the SF sample reveals an increasing scatter with redshift, indicating that it is still being built at early epochs. The SF galaxies make up a tight sequence in the SFR-M{sub *} plane at high redshift, whose scatter increases with time alongside the consolidation of the passive sequence. We also confirm the anti-correlation between sSFR and stellar mass, pointing at a key role of the former in determining the galaxy downsizing, as the most significant means of diagnostics of the star formation efficiency. Likewise, an anti-correlation between sSFR and metallicity can be established for the SF galaxies, while on the contrary more active

  4. The zCOSMOS survey : the role of the environment in the evolution of the luminosity function of different galaxy types

    NARCIS (Netherlands)

    Zucca, E.; Bardelli, S.; Bolzonella, M.; Zamorani, G.; Ilbert, O.; Pozzetti, L.; Mignoli, M.; Kovac, K.; Lilly, S.; Tresse, L.; Tasca, L.; Cassata, P.; Halliday, C.; Vergani, D.; Caputi, K.; Carollo, C. M.; Contini, T.; Kneib, J-P.; Le Fevre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bongiorno, A.; Coppa, G.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Lamareille, F.; Le Borgne, J-F.; Le Brun, V.; Maier, C.; Pello, R.; Peng, Y.; Perez-Montero, E.; Ricciardelli, E.; Silverman, J. D.; Tanaka, M.; Abbas, U.; Bottini, D.; Cappi, A.; Cimatti, A.; Guzzo, L.; Koekemoer, A. M.; Leauthaud, A.; Maccagni, D.; Marinoni, C.; McCracken, H. J.; Memeo, P.; Meneux, B.; Moresco, M.; Oesch, P.; Porciani, C.; Scaramella, R.; Arnouts, S.; Aussel, H.; Capak, P.; Kartaltepe, J.; Salvato, M.; Sanders, D.; Scoville, N.; Taniguchi, Y.; Thompson, D.

    2009-01-01

    Aims. An unbiased and detailed characterization of the galaxy luminosity function (LF) is a basic requirement in many astrophysical issues: it is of particular interest in assessing the role of the environment in the evolution of the LF of different galaxy types. Methods. We studied the evolution in

  5. The zCOSMOS survey: the role of the environment in the evolution of the luminosity function of different galaxy types

    NARCIS (Netherlands)

    Zucca, E.; Bardelli, S.; Bolzonella, M.; Zamorani, G.; Ilbert, O.; Pozzetti, L.; Mignoli, M.; Kovač, K.; Lilly, S.; Tresse, L.; Tasca, L.; Cassata, P.; Halliday, C.; Vergani, D.; Caputi, K.; Carollo, C. M.; Contini, T.; Kneib, J.-P.; Le Fèvre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bongiorno, A.; Coppa, G.; Cucciati, O.; de La Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Lamareille, F.; Le Borgne, J.-F.; Le Brun, V.; Maier, C.; Pellò, R.; Peng, Y.; Perez-Montero, E.; Ricciardelli, E.; Silverman, J. D.; Tanaka, M.; Abbas, U.; Bottini, D.; Cappi, A.; Cimatti, A.; Guzzo, L.; Koekemoer, A. M.; Leauthaud, A.; Maccagni, D.; Marinoni, C.; McCracken, H. J.; Memeo, P.; Meneux, B.; Moresco, M.; Oesch, P.; Porciani, C.; Scaramella, R.; Arnouts, S.; Aussel, H.; Capak, P.; Kartaltepe, J.; Salvato, M.; Sanders, D.; Scoville, N.; Taniguchi, Y.; Thompson, D.

    2009-01-01

    Aims. An unbiased and detailed characterization of the galaxy luminosity function (LF) is a basic requirement in many astrophysical issues: it is of particular interest in assessing the role of the environment in the evolution of the LF of different galaxy types. Methods: We studied the evolution in

  6. Galaxy formation in the Planck cosmology - I. Matching the observed evolution of star formation rates, colours and stellar masses

    Science.gov (United States)

    Henriques, Bruno M. B.; White, Simon D. M.; Thomas, Peter A.; Angulo, Raul; Guo, Qi; Lemson, Gerard; Springel, Volker; Overzier, Roderik

    2015-08-01

    We have updated the Munich galaxy formation model to the Planck first-year cosmology, while modifying the treatment of baryonic processes to reproduce recent data on the abundance and passive fractions of galaxies from z = 3 down to z = 0. Matching these more extensive and more precise observational results requires us to delay the reincorporation of wind ejecta, to lower the surface density threshold for turning cold gas into stars, to eliminate ram-pressure stripping in haloes less massive than {˜ }10^{14}{ M_{⊙}}, and to modify our model for radio mode feedback. These changes cure the most obvious failings of our previous models, namely the overly early formation of low-mass galaxies and the overly large fraction of them that are passive at late times. The new model is calibrated to reproduce the observed evolution both of the stellar mass function and of the distribution of star formation rate at each stellar mass. Massive galaxies (log M⋆/M⊙ ≥ 11.0) assemble most of their mass before z = 1 and are predominantly old and passive at z = 0, while lower mass galaxies assemble later and, for log M⋆/M⊙ ≤ 9.5, are still predominantly blue and star forming at z = 0. This phenomenological but physically based model allows the observations to be interpreted in terms of the efficiency of the various processes that control the formation and evolution of galaxies as a function of their stellar mass, gas content, environment and time.

  7. Euroconference on the appropriate modellings of galaxy evolution from their cosmological formation to their presently observable structures

    CERN Document Server

    Stasińska, Grażyna; Harfst, Stefan; Kroupa, Pavel; Theis, Christian; THE EVOLUTION OF GALAXIES

    2003-01-01

    Galaxies have a history This has become clear from recent sky surveys which have shown that distant galaxies, formed early in the life of the Universe, differ from the nearby ones New observational windows at ultraviolet, infrared and millimetric wavelengths (provided by ROSAT, IRAM, IUE, IRAS, ISO) have revealed that galaxies contain a wealth of components very hot gas, atomic hydrogen, molecules, dust, dark matter A significant advance is expected from the results of new instruments (VLT, FIRST, XMM) which will allow one to explore the most distant Universe Three Euroconferences were planned to punctuate this new epoch in galactic research, bringing together specialists in various fields of Astronomy This book contains the proceedings of the third conference and presents the actual state-of-the-art of modelling galaxy evolution

  8. Combining Galaxy-Galaxy Lensing and Galaxy Clustering: A Practical Approach

    Science.gov (United States)

    Park, Youngsoo; Krause, Elisabeth; Dodelson, Scott; Jain, Bhuvnesh; Dark Energy Survey Collaboration

    2015-04-01

    Combining galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth rate of large scale structure, a quantity that will shed light on the mechanism driving the acceleration of the Universe. The Dark Energy Survey (DES) is a prime candidate for such an analysis, with its measurements of both the distribution of galaxies on the sky and the tangential shears of background galaxies induced by these foreground lenses. By constructing an end-to-end analysis that combines large-scale galaxy clustering and small-scale galaxy-galaxy lensing, we forecast the potential of a combined probes analysis on DES datasets. In particular, we develop a practical approach to a DES combined probes analysis by jointly modeling the assumptions and systematics affecting the data vectors, employing a shared halo model, HOD parametrization, photometric redshift errors, and shear measurement errors. We also study the effect of external priors on different subsets of these parameters. We conclude that data from the first year of DES will provide powerful constraints on the evolution of structure growth in the universe, constraining the growth function to better than 5%.

  9. Environmental Effects on Galaxy Evolution. II. Quantifying the Tidal Features in NIR Images of the Cluster Abell 85

    Science.gov (United States)

    Venkatapathy, Y.; Bravo-Alfaro, H.; Mayya, Y. D.; Lobo, C.; Durret, F.; Gamez, V.; Valerdi, M.; Granados-Contreras, A. P.; Navarro-Poupard, F.

    2017-12-01

    This work is part of a series of papers devoted to investigating the evolution of cluster galaxies during their infall. In the present article, we image in NIR a selected sample of galaxies throughout the massive cluster Abell 85 (z = 0.055). We obtain (JHK‧) photometry for 68 objects, reaching ˜1 mag arcsec-2 deeper than 2MASS. We use these images to unveil asymmetries in the outskirts of a sample of bright galaxies and develop a new asymmetry index, {α }{An}, which allows us to quantify the degree of disruption by the relative area occupied by the tidal features on the plane of the sky. We measure the asymmetries for a subsample of 41 large-area objects, finding clear asymmetries in 10 galaxies; most of these are in groups and pairs projected at different clustercentric distances, and some of them are located beyond R 500. Combining information on the H I gas content of blue galaxies and the distribution of substructures across Abell 85 with the present NIR asymmetry analysis, we obtain a very powerful tool to confirm that tidal mechanisms are indeed present and are currently affecting a fraction of galaxies in Abell 85. However, when comparing our deep NIR images with UV blue images of two very disrupted (jellyfish) galaxies in this cluster, we discard the presence of tidal interactions down to our detection limit. Our results suggest that ram-pressure stripping is at the origin of such spectacular disruptions. We conclude that across a complex cluster like Abell 85, environmental mechanisms, both gravitational and hydrodynamical, are playing an active role in driving galaxy evolution.

  10. The scatter and evolution of the global hot gas properties of simulated galaxy cluster populations

    Science.gov (United States)

    Le Brun, Amandine M. C.; McCarthy, Ian G.; Schaye, Joop; Ponman, Trevor J.

    2017-04-01

    We use the cosmo-OverWhelmingly Large Simulation (cosmo-OWLS) suite of cosmological hydrodynamical simulations to investigate the scatter and evolution of the global hot gas properties of large simulated populations of galaxy groups and clusters. Our aim is to compare the predictions of different physical models and to explore the extent to which commonly adopted assumptions in observational analyses (e.g. self-similar evolution) are violated. We examine the relations between (true) halo mass and the X-ray temperature, X-ray luminosity, gas mass, Sunyaev-Zel'dovich (SZ) flux, the X-ray analogue of the SZ flux (YX) and the hydrostatic mass. For the most realistic models, which include active galactic nuclei (AGN) feedback, the slopes of the various mass-observable relations deviate substantially from the self-similar ones, particularly at late times and for low-mass clusters. The amplitude of the mass-temperature relation shows negative evolution with respect to the self-similar prediction (i.e. slower than the prediction) for all models, driven by an increase in non-thermal pressure support at higher redshifts. The AGN models predict strong positive evolution of the gas mass fractions at low halo masses. The SZ flux and YX show positive evolution with respect to self-similarity at low mass but negative evolution at high mass. The scatter about the relations is well approximated by log-normal distributions, with widths that depend mildly on halo mass. The scatter decreases significantly with increasing redshift. The exception is the hydrostatic mass-halo mass relation, for which the scatter increases with redshift. Finally, we discuss the relative merits of various hot gas-based mass proxies.

  11. THE REDSHIFT EVOLUTION OF THE MEAN TEMPERATURE, PRESSURE, AND ENTROPY PROFILES IN 80 SPT-SELECTED GALAXY CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, M.; Benson, B. A.; Vikhlinin, A.; Aird, K. A.; Allen, S. W.; Bautz, M.; Bayliss, M.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Hlavacek-Larrondo, J.; Holder, G. P.; Holzapfel, W. L.; Hrubes, J. D.; Jones, C.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McMahon, J. J.; Meyer, S. S.; Miller, E. D.; Mocanu, L.; Mohr, J. J.; Murray, S. S.; Padin, S.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.; Zahn, O.; Zenteno, A.

    2014-09-24

    We present the results of an X-ray analysis of 80 galaxy clusters selected in the 2500 deg(2) South Pole Telescope survey and observed with the Chandra X-ray Observatory. We divide the full sample into subsamples of ~20 clusters based on redshift and central density, performing a joint X-ray spectral fit to all clusters in a subsample simultaneously, assuming self-similarity of the temperature profile. This approach allows us to constrain the shape of the temperature profile over 0 < r < 1.5R (500), which would be impossible on a per-cluster basis, since the observations of individual clusters have, on average, 2000 X-ray counts. The results presented here represent the first constraints on the evolution of the average temperature profile from z = 0 to z = 1.2. We find that high-z (0.6 < z < 1.2) clusters are slightly (~30%) cooler both in the inner (r < 0.1R (500)) and outer (r > R (500)) regions than their low-z (0.3 < z < 0.6) counterparts. Combining the average temperature profile with measured gas density profiles from our earlier work, we infer the average pressure and entropy profiles for each subsample. Confirming earlier results from this data set, we find an absence of strong cool cores at high z, manifested in this analysis as a significantly lower observed pressure in the central 0.1R (500) of the high-z cool-core subset of clusters compared to the low-z cool-core subset. Overall, our observed pressure profiles agree well with earlier lower-redshift measurements, suggesting minimal redshift evolution in the pressure profile outside of the core. We find no measurable redshift evolution in the entropy profile at r lsim 0.7R (500)—this may reflect a long-standing balance between cooling and feedback over long timescales and large physical scales. We observe a slight flattening of the entropy profile at r gsim R (500) in our high-z subsample. This flattening is consistent with a temperature bias due to the enhanced (~3×) rate at which group-mass (~2

  12. EVOLUTION OF THE SIZES OF GALAXIES OVER 7 < z < 12 REVEALED BY THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Yoshiaki; Ouchi, Masami [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa 277-8582 (Japan); Curtis-Lake, Emma; McLure, Ross J.; Dunlop, James S.; Bowler, Rebecca A. A.; Rogers, Alexander B.; Cirasuolo, Michele [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Schenker, Matthew A.; Ellis, Richard S. [Department of Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Robertson, Brant E.; Schneider, Evan; Stark, Daniel P. [Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Charlot, Stephane [UPMC-CNRS, UMR7095, Institut d' Astrophysique, F-75014 Paris (France); Shimasaku, Kazuhiro [Department of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Furlanetto, Steven R., E-mail: ono@icrr.u-tokyo.ac.jp [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2013-11-10

    We analyze the redshift- and luminosity-dependent sizes of dropout galaxy candidates in the redshift range z ∼ 7-12 using deep images from the 2012 Hubble Ultra Deep Field (UDF12) campaign, which offers two advantages over that used in earlier work. First, we utilize the increased signal-to-noise ratio offered by the UDF12 imaging to provide improved measurements for known galaxies at z ≅ 6.5-8 in the HUDF. Second, because the UDF12 data have allowed the construction of the first robust galaxy sample in the HUDF at z > 8, we have been able to extend the measurement of average galaxy size out to higher redshifts. Restricting our measurements to sources detected at >15σ, we confirm earlier indications that the average half-light radii of z ∼ 7-12 galaxies are extremely small, 0.3-0.4 kpc, comparable to the sizes of giant molecular associations in local star-forming galaxies. We also confirm that there is a clear trend of decreasing half-light radius with increasing redshift, and provide the first evidence that this trend continues beyond z ≅ 8. Modeling the evolution of the average half-light radius as a power law, ∝(1 + z) {sup s}, we obtain a best-fit index of s=-1.30{sup +0.12}{sub -0.14} over z ∼ 4-12. A clear size-luminosity relation is evident in our dropout samples. This relation can be interpreted in terms of a constant surface density of star formation over a range in luminosity of 0.05-1.0 L{sub z=3}. The average star formation surface density in dropout galaxies is 2-3 orders of magnitude lower than that found in extreme starburst galaxies, but is comparable to that seen today in the centers of normal disk galaxies.

  13. Evolution in the Dust Lane Fraction of Edge-on L* V Spiral Galaxies Since z = 0.8

    Science.gov (United States)

    Holwerda, B. W.; Dalcanton, J. J.; Radburn-Smith, D.; de Jong, R. S.; Guhathakurta, P.; Koekemoer, A.; Allen, R. J.; Böker, T.

    2012-07-01

    The presence of a well-defined and narrow dust lane in an edge-on spiral galaxy is the observational signature of a thin and dense molecular disk, in which gravitational collapse has overcome turbulence. Using a sample of galaxies out to z ~ 1 extracted from the COSMOS survey, we identify the fraction of massive (L* V ) disks that display a dust lane. Our goal is to explore the evolution in the stability of the molecular interstellar medium (ISM) disks in spiral galaxies over a cosmic timescale. We check the reliability of our morphological classifications against changes in rest-frame wavelength, resolution, and cosmic dimming with (artificially redshifted) images of local galaxies from the Sloan Digital Sky Survey. We find that the fraction of L* V disks with dust lanes in COSMOS is consistent with the local fraction (≈80%) out to z ~ 0.7. At z = 0.8, the dust lane fraction is only slightly lower. A somewhat lower dust lane fraction in starbursting galaxies tentatively supports the notion that a high specific star formation rate can efficiently destroy or inhibit a dense molecular disk. A small subsample of higher redshift COSMOS galaxies display low internal reddening (E[B - V]), as well as a low incidence of dust lanes. These may be disks in which the growth of the dusty ISM disk lags behind that of the stellar disk. We note that at z = 0.8, the most massive galaxies display a lower dust lane fraction than lower mass galaxies. A small contribution of recent mergers or starbursts to this most massive population may be responsible. The fact that the fraction of galaxies with dust lanes in COSMOS is consistent with little or no evolution implies that models to explain the spectral energy distribution or the host galaxy dust extinction of supernovae based on local galaxies are still applicable to higher redshift spirals. It also suggests that dust lanes are long-lived phenomena or can be reformed over very short timescales.

  14. The First Billion Years project: constraining the dust attenuation law of star-forming galaxies at z ≃ 5

    Science.gov (United States)

    Cullen, F.; McLure, R. J.; Khochfar, S.; Dunlop, J. S.; Dalla Vecchia, C.

    2017-09-01

    We present the results of a study investigating the dust attenuation law at z ≃ 5, based on synthetic spectral energy distributions (SEDs) calculated for a sample of N = 498 galaxies drawn from the First Billion Years (FiBY) simulation project. The simulated galaxies at z ≃ 5, which have M1500 ≤ -18.0 and 7.5 ≤ log(M/M}_{⊙}) ≤ 10.2, display a mass-dependent α-enhancement, with a median value of [α /{Fe}]_{z=5} ˜eq 4 × [α /{Fe}]_{Z_{⊙}}. The median Fe/H ratio of the simulated galaxies is 0.14 ± 0.05 which produces steep intrinsic ultraviolet (UV) continuum slopes; 〈βI〉 = -2.4 ± 0.05. Using a set of simple dust attenuation models, in which the wavelength-dependent attenuation is assumed to be of the form A(λ) ∝ λn, we explore the parameter values which best reproduce the observed z = 5 luminosity function (LF) and colour-magnitude relation (CMR). We find that a simple model in which the absolute UV attenuation is a linearly increasing function of log stellar mass (A1500 = 0.5 × log(M/M⊙) - 3.3), and the dust attenuation slope (n) is within the range -0.7 ≤ n ≤ -0.3, can successfully reproduce the LF and CMR over a wide range of stellar population synthesis model assumptions, including the effects of massive binaries. This range of attenuation curves is consistent with a power-law fit to the Calzetti attenuation law in the UV (n = -0.55). In contrast, curves as steep as the Small Magellanic Cloud extinction curve (n = -1.24) are formally ruled out. Finally, we show that our models are consistent with recent 1.3 mm Atacama Large Millimeter Array observations of the Hubble Ultra Deep Field, and predict the form of the z ≃ 5 infrared excess (IRX)-β relation.

  15. Populating H2 and CO in galaxy simulation with dust evolution

    Science.gov (United States)

    Chen, Li-Hsin; Hirashita, Hiroyuki; Hou, Kuan-Chou; Aoyama, Shohei; Shimizu, Ikkoh; Nagamine, Kentaro

    2018-02-01

    There are two major theoretical issues for the star formation law (the relation between the surface densities of molecular gas and star formation rate on a galaxy scale): (i) At low metallicity, it is not obvious that star-forming regions are rich in H2 because the H2 formation rate depends on the dust abundance; and (ii) whether or not CO really traces H2 is uncertain, especially at low metallicity. To clarify these issues, we use a hydrodynamic simulation of an isolated disc galaxy with a spatial resolution of a few tens parsecs. The evolution of dust abundance and grain size distribution is treated consistently with the metal enrichment and the physical state of the interstellar medium. We compute the H2 and CO abundances using a subgrid post-processing model based on the dust abundance and the dissociating radiation field calculated in the simulation. We find that when the metallicity is ≲ 0.4 Z⊙ (t ages, we also find that adopting the so-called MRN grain size distribution with an appropriate dust-to-metal ratio over the entire disc gives reasonable estimates for the H2 and CO abundances. For CO, improving the spatial resolution of the simulation is important, while the H2 abundance is not sensitive to subresolution structures at Z ≳ 0.4 Z⊙.

  16. The Small-Scale Structure of the Magellanic Stream as a Foundation for Galaxy Evolution

    Directory of Open Access Journals (Sweden)

    Nigra, L.

    2010-06-01

    Full Text Available The Magellanic Stream (MS is the nearest example of agaseous trail formed by interacting galaxies. While the substantial gas masses in these kinds of circumgalactic structures are postulated to represent important sources of fuel for future star formation, the mechanisms whereby this material might be accreted back into galaxies remain unclear. Recent neutral hydrogen (HI observations have demonstrated that the northern portion of the MS, which probably has been interacting with the Milky Way's hot gaseous halo for close to 1000~Myr, has a larger spatial extent than previously recognized, while also containing significant amounts of small-scale structure. After a brief consideration of the large-scale kinematics of the MS as traced by the recently-discovered extension of the MS, we explore the aging process of the MS gas through the operation of various hydrodynamic instabilities and interstellar turbulence. This in turn leads to consideration of processes whereby MS material survives as cool gas, and yet also evidently fails to form stars.Parallels between the MS and extragalactic tidal features are briefly discussed with an emphasis on steps toward establishing what the MS reveals about the critical role of local processes in determining the evolution of these kinds of systems.

  17. The small-scale structure of the Magellanic stream as a foundation for galaxy evolution

    Directory of Open Access Journals (Sweden)

    Stanimirović S.

    2010-01-01

    Full Text Available The Magellanic Stream (MS is the nearest example of a gaseous trail formed by interacting galaxies. While the substantial gas masses in these kinds of circumgalactic structures are postulated to represent important sources of fuel for future star formation, the mechanisms whereby this material might be accreted back into galaxies remain unclear. Recent neutral hydrogen (HI observations have demonstrated that the northern portion of the MS, which probably has been interacting with the Milky Way's hot gaseous halo for close to 1000 Myr, has a larger spatial extent than previously recognized, while also containing significant amounts of small-scale structure. After a brief consideration of the large-scale kinematics of the MS as traced by the recently-discovered extension of the MS, we explore the aging process of the MS gas through the operation of various hydrodynamic instabilities and interstellar turbulence. This in turn leads to consideration of processes whereby MS material survives as cool gas, and yet also evidently fails to form stars. Parallels between the MS and extragalactic tidal features are brie'y discussed with an emphasis on steps toward establishing what the MS reveals about the critical role of local processes in determining the evolution of these kinds of systems.

  18. Supernova-driven outflows and chemical evolution of dwarf spheroidal galaxies.

    Science.gov (United States)

    Qian, Yong-Zhong; Wasserburg, G J

    2012-03-27

    We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized systems with their stars undergoing slow internal evolution. For a wide variety of infall histories of unprocessed baryonic matter to feed star formation, most of the observed MDs can be well described by our model. The key requirement is that the fraction of the gas mass lost by supernova-driven outflows is close to unity. This model also predicts a relationship between the total stellar mass and the mean metallicity for dSphs in accord with properties of their dark matter halos. The model further predicts as a natural consequence that the abundance ratios [E/Fe] for elements such as O, Mg, and Si decrease for stellar populations at the higher end of the [Fe/H] range in a dSph. We show that, for infall rates far below the net rate of gas loss to star formation and outflows, the MD in our model is very sharply peaked at one [Fe/H] value, similar to what is observed in most globular clusters. This result suggests that globular clusters may be end members of the same family as dSphs.

  19. Using the XMM-Newton Optical Monitor to Study Cluster Galaxy Evolution

    Science.gov (United States)

    Miller, Neal A.; O'Steen, Richard; Yen, Steffi; Kuntz, K. D.; Hammer, Derek

    2012-02-01

    We explore the application of XMM-Newton Optical Monitor (XMM-OM) ultraviolet (UV) data to study galaxy evolution. Our sample is constructed as the intersection of all Abell clusters with z indicative of differences in star formation history. This is particularly true for UVW1 data, as the relative abundance of data collected using this filter and its depth make it an attractive choice. Available tools that use stellar synthesis libraries to fit the UV and optical photometric data may also be used, thereby better describing star formation history within the past billion years and providing estimates of total stellar mass that include contributions from young stars. Finally, color-color diagrams that include XMM-OM UV data appear useful to the photometric identification of both extragalactic and stellar sources.

  20. GRAVITATIONAL WAVE BACKGROUND FROM BINARY MERGERS AND METALLICITY EVOLUTION OF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Nakazato, Ken’ichiro; Sago, Norichika [Faculty of Arts and Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Niino, Yuu, E-mail: nakazato@artsci.kyushu-u.ac.jp [Division of Optical and Infrared Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-12-01

    The cosmological evolution of the binary black hole (BH) merger rate and the energy density of the gravitational wave (GW) background are investigated. To evaluate the redshift dependence of the BH formation rate, BHs are assumed to originate from low-metallicity stars, and the relations between the star formation rate, metallicity and stellar mass of galaxies are combined with the stellar mass function at each redshift. As a result, it is found that when the energy density of the GW background is scaled with the merger rate at the local universe, the scaling factor does not depend on the critical metallicity for the formation of BHs. Also taking into account the merger of binary neutron stars, a simple formula to express the energy spectrum of the GW background is constructed for the inspiral phase. The relation between the local merger rate and the energy density of the GW background will be examined by future GW observations.

  1. Pleiotropy constrains the evolution of protein but not regulatory sequences in a transcription regulatory network influencing complex social behaviours

    Directory of Open Access Journals (Sweden)

    Daria eMolodtsova

    2014-12-01

    Full Text Available It is increasingly apparent that genes and networks that influence complex behaviour are evolutionary conserved, which is paradoxical considering that behaviour is labile over evolutionary timescales. How does adaptive change in behaviour arise if behaviour is controlled by conserved, pleiotropic, and likely evolutionary constrained genes? Pleiotropy and connectedness are known to constrain the general rate of protein evolution, prompting some to suggest that the evolution of complex traits, including behaviour, is fuelled by regulatory sequence evolution. However, we seldom have data on the strength of selection on mutations in coding and regulatory sequences, and this hinders our ability to study how pleiotropy influences coding and regulatory sequence evolution. Here we use population genomics to estimate the strength of selection on coding and regulatory mutations for a transcriptional regulatory network that influences complex behaviour of honey bees. We found that replacement mutations in highly connected transcription factors and target genes experience significantly stronger negative selection relative to weakly connected transcription factors and targets. Adaptively evolving proteins were significantly more likely to reside at the periphery of the regulatory network, while proteins with signs of negative selection were near the core of the network. Interestingly, connectedness and network structure had minimal influence on the strength of selection on putative regulatory sequences for both transcription factors and their targets. Our study indicates that adaptive evolution of complex behaviour can arise because of positive selection on protein-coding mutations in peripheral genes, and on regulatory sequence mutations in both transcription factors and their targets throughout the network.

  2. GALAXY EVOLUTION AT HIGH REDSHIFT: OBSCURED STAR FORMATION, GRB RATES, COSMIC REIONIZATION, AND MISSING SATELLITES

    Energy Technology Data Exchange (ETDEWEB)

    Lapi, A.; Mancuso, C.; Celotti, A.; Danese, L. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy)

    2017-01-20

    We provide a holistic view of galaxy evolution at high redshifts z ≳ 4, which incorporates the constraints from various astrophysical/cosmological probes, including the estimate of the cosmic star formation rate (SFR) density from UV/IR surveys and long gamma-ray burst (GRBs) rates, the cosmic reionization history following the latest Planck measurements, and the missing satellites issue. We achieve this goal in a model-independent way by exploiting the SFR functions derived by Mancuso et al. on the basis of an educated extrapolation of the latest UV/far-IR data from HST / Herschel , and already tested against a number of independent observables. Our SFR functions integrated down to a UV magnitude limit M {sub UV} ≲ −13 (or SFR limit around 10{sup −2} M {sub ⊙} yr{sup −1}) produce a cosmic SFR density in excellent agreement with recent determinations from IR surveys and, taking into account a metallicity ceiling Z ≲ Z {sub ⊙}/2, with the estimates from long GRB rates. They also yield a cosmic reionization history consistent with that implied by the recent measurements of the Planck mission of the electron scattering optical depth τ {sub es} ≈ 0.058; remarkably, this result is obtained under a conceivable assumption regarding the average value f {sub esc} ≈ 0.1 of the escape fraction for ionizing photons. We demonstrate via the abundance-matching technique that the above constraints concurrently imply galaxy formation becoming inefficient within dark matter halos of mass below a few 10{sup 8} M {sub ⊙}; pleasingly, such a limit is also required so as not to run into the missing satellites issue. Finally, we predict a downturn of the Galaxy luminosity function faintward of M {sub UV} ≲ −12, and stress that its detailed shape, to be plausibly probed in the near future by the JWST , will be extremely informative on the astrophysics of galaxy formation in small halos, or even on the microscopic nature of the dark matter.

  3. Galaxy Evolution Studies with the SPace IR Telescope for Cosmology and Astrophysics (SPICA): The Power of IR Spectroscopy

    Science.gov (United States)

    Spinoglio, L.; Alonso-Herrero, A.; Armus, L.; Baes, M.; Bernard-Salas, J.; Bianchi, S.; Bocchio, M.; Bolatto, A.; Bradford, C.; Braine, J.; Carrera, F. J.; Ciesla, L.; Clements, D. L.; Dannerbauer, H.; Doi, Y.; Efstathiou, A.; Egami, E.; Fernández-Ontiveros, J. A.; Ferrara, A.; Fischer, J.; Franceschini, A.; Gallerani, S.; Giard, M.; González-Alfonso, E.; Gruppioni, C.; Guillard, P.; Hatziminaoglou, E.; Imanishi, M.; Ishihara, D.; Isobe, N.; Kaneda, H.; Kawada, M.; Kohno, K.; Kwon, J.; Madden, S.; Malkan, M. A.; Marassi, S.; Matsuhara, H.; Matsuura, M.; Miniutti, G.; Nagamine, K.; Nagao, T.; Najarro, F.; Nakagawa, T.; Onaka, T.; Oyabu, S.; Pallottini, A.; Piro, L.; Pozzi, F.; Rodighiero, G.; Roelfsema, P.; Sakon, I.; Santini, P.; Schaerer, D.; Schneider, R.; Scott, D.; Serjeant, S.; Shibai, H.; Smith, J.-D. T.; Sobacchi, E.; Sturm, E.; Suzuki, T.; Vallini, L.; van der Tak, F.; Vignali, C.; Yamada, T.; Wada, T.; Wang, L.

    2017-11-01

    IR spectroscopy in the range 12-230 μm with the SPace IR telescope for Cosmology and Astrophysics (SPICA) will reveal the physical processes governing the formation and evolution of galaxies and black holes through cosmic time, bridging the gap between the James Webb Space Telescope and the upcoming Extremely Large Telescopes at shorter wavelengths and the Atacama Large Millimeter Array at longer wavelengths. The SPICA, with its 2.5-m telescope actively cooled to below 8 K, will obtain the first spectroscopic determination, in the mid-IR rest-frame, of both the star-formation rate and black hole accretion rate histories of galaxies, reaching lookback times of 12 Gyr, for large statistically significant samples. Densities, temperatures, radiation fields, and gas-phase metallicities will be measured in dust-obscured galaxies and active galactic nuclei, sampling a large range in mass and luminosity, from faint local dwarf galaxies to luminous quasars in the distant Universe. Active galactic nuclei and starburst feedback and feeding mechanisms in distant galaxies will be uncovered through detailed measurements of molecular and atomic line profiles. The SPICA's large-area deep spectrophotometric surveys will provide mid-IR spectra and continuum fluxes for unbiased samples of tens of thousands of galaxies, out to redshifts of z 6.

  4. Synthetic nebular emission from massive galaxies - I: origin of the cosmic evolution of optical emission-line ratios

    Science.gov (United States)

    Hirschmann, Michaela; Charlot, Stephane; Feltre, Anna; Naab, Thorsten; Choi, Ena; Ostriker, Jeremiah P.; Somerville, Rachel S.

    2017-12-01

    Galaxies occupy different regions of the [O III]λ5007/H β-versus-[N II]λ6584/H α emission-line ratio diagram in the distant and local Universe. We investigate the origin of this intriguing result by modelling self-consistently, for the first time, nebular emission from young stars, accreting black holes (BHs) and older, post-asymptotic giant branch (post-AGB) stellar populations in galaxy formation simulations in a full cosmological context. In post-processing, we couple new-generation nebular-emission models with high-resolution, cosmological zoom-in simulations of massive galaxies to explore which galaxy physical properties drive the redshift evolution of the optical-line ratios [O III]λ5007/H β, [N II]λ6584/H α, [S II]λλ6717, 6731/H α and [O I]λ6300/H α. The line ratios of simulated galaxies agree well with observations of both star-forming and active local Sloan Digital Sky Survey galaxies. Towards higher redshifts, at fixed galaxy stellar mass, the average [O III]/H β is predicted to increase and [N II]/H α, [S II]/H α and [O I]/H α to decrease - widely consistent with observations. At fixed stellar mass, we identify star formation history, which controls nebular emission from young stars via the ionization parameter, as the primary driver of the cosmic evolution of [O III]/H β and [N II]/H α. For [S II]/H α and [O I]/H α, this applies only to redshifts greater than z = 1.5, the evolution at lower redshift being driven in roughly equal parts by nebular emission from active galactic nuclei and post-AGB stellar populations. Instead, changes in the hardness of ionizing radiation, ionized-gas density, the prevalence of BH accretion relative to star formation and the dust-to-metal mass ratio (whose impact on the gas-phase N/O ratio we model at fixed O/H) play at most a minor role in the cosmic evolution of simulated galaxy line ratios.

  5. The evolution of X-ray galaxy clusters as a constraint of Omega(0)

    DEFF Research Database (Denmark)

    Oukbir, J.

    1998-01-01

    Clusters of galaxies are rare objects and as such, their properties are particularly sensitive to the underlying density fluctuations. Therefore, the cluster population provides very stringent constraints on models of galaxy formation. We here show how self-consistent modeling of X-ray galaxy dus...

  6. The stellar mass-size evolution of galaxies from z=7 to z=0

    NARCIS (Netherlands)

    Mosleh, Moein

    2013-01-01

    One of the important properties of galaxies is their sizes which correlate with their stellar masses. Evidence is provided by many recent studies that the sizes of galaxies were smaller at higher redshifts compared to galaxies of similar mass in the local Universe. It is essential to understand

  7. Anomalous evolution of the dwarf galaxy HIPASS J1321-31

    NARCIS (Netherlands)

    Pritzl, BJ; Knezek, PM; Gallagher, JS; Grossi, M; Disney, MJ; Minchin, RF; Freeman, KC; Tolstoy, E; Saha, A

    2003-01-01

    We present Hubble Space Telescope/WFPC2 observations of the dwarf galaxy HIPASS J1321-31. This unusual galaxy lies in the direction of the Centaurus A group of galaxies and has a color-magnitude diagram with a distinctive red plume of luminous stars. This feature could arise from (1) a red giant

  8. VizieR Online Data Catalog: FourStar galaxy evolution survey (ZFOURGE) (Straatman+, 2016)

    Science.gov (United States)

    Straatman, C. M. S.; Spitler, L. R.; Quadri, R. F.; Labbe, I.; Glazebrook, K.; Persson, S. E.; Papovich, C.; Tran, K.-V.; Brammer, G. B.; Cowley, M.; Tomczak, A.; Nanayakkara, T.; Alcorn, L.; Allen, R.; Broussard, A.; van Dokkum, P.; Forrest, B.; van Houdt, J.; Kacprzak, G. G.; Kawinwanichakij, L.; Kelson, D. D.; Lee, J.; McCarthy, P. J.; Mehrtens, N.; Monson, A.; Murphy, D.; Rees, G.; Tilvi, V.; Whitaker, K. E.

    2017-03-01

    We present the FourStar galaxy evolution survey (ZFOURGE) photometric catalogs comprising >70000 galaxies, selected from ultradeep Ks-band detection images (25.5-26.5 AB mag, 5σ, total). We use 5 near-IR medium-bandwidth filters (J1, J2, J3, Hs, Hl) as well as broad-band Ks at 1.05-2.16 micron to 25-26 AB at a seeing of ~0.5 arcsec. Each field has ancillary imaging in 26-40 filters at 0.3-8 micron. We derive photometric redshifts, rest-frame U-V and V-J colors, and stellar population properties from SED fitting. The photometric redshifts have uncertainty σz=0.010, 0.009, and 0.011 in CDFS, COSMOS and UDS, respectively, if compared with spectroscopic redshifts. A pair test indicates σz,pairs=0.01-0.02 at 1PACS data. FourStar data are gathered with the 6.5m Magellan Telescopes located at Las Campanas observatory, Chile, during a total of 45 nights from December 2010 until November 2012. The FourStar instrument has 6 custom-made near_IR filters: J1, 1.0540 um, medium-bandwidth J2, 1.1448 um, medium-bandwidth J3, 1.2802 um, medium-bandwidth Hs, 1.5544 um, medium-bandwidth Hl, 1.7020 um, medium-bandwidth Ks, 2.1538 um, broad-bandwidth Observing conditions were excellent with a seeing of 0.4 to 0.5" for most individual frames. We paid special attention to the Ks-band, which resulted in a median 0.4 arcsecond seeing. (37 data files).

  9. Star-formation and stellar feedback recipes in galaxy evolution models

    Science.gov (United States)

    Hensler, Gerhard; Recchi, Simone; Ploeckinger, Sylvia; Kuehtreiber, Matthias; Steyrleithner, Patrick; Liu, Lei

    2015-08-01

    Modeling galaxy formation and evolution is critically depending on star formation (SF). Since cosmological and galaxy-scale simulations cannot resolve the spatial and density scales on which SF acts, a large variety of methods are developed and applied over the last decades. Nonetheless, we are still in the test phase how the choice of parameters affects the models and how they agree with observations.As a simple ansatz, recipes are based on power-law SF dependences on gas density as justified by gas cooling and collapse timescales. In order to prevent SF spread throughout the gas, temperature and density thresholds are also used, although gas dynamical effects, like e.g. gas infall, seem to trigger SF significantly.The formed stars influence their environment immediately by energetic and materialistic feedback. It has been experienced in numerical models that supernova typeII explosions act with a too long time delay to regulate the SF, but that winds and ionizing radiation by massive stars must be included. The implementation of feedback processes, their efficiencies and timescales, is still in an experimental state, because they depend also on the physical state of the surrounding interstellar medium (ISM).Combining a SF-gas density relation with stellar heating vs. gas cooling and taking the temperature dependence into account, we have derived an analytical expression of self-regulated SF which is free of arbitrary parameters. We have performed numerical models to study this recipe and different widely used SF criteria in both, particle and grid codes. Moreover, we compare the SF behavior between single-gas phase and multi-phase treatments of the ISM.Since dwarf galaxies (DGs) are most sensitive to environmental influences and contain only low SF rates, we explore two main affects on their models: 1. For external effects we compare SF rates of isolated and ram-pressure suffering DGs. Moreover, we find a SF enhancement in tidal-tail DGs by the compressive tidal

  10. ngVLA Key Science Goal 3: Charting the Assembly, Structure, and Evolution of Galaxies Over Cosmic Time

    Science.gov (United States)

    Riechers, Dominik A.; Bolatto, Alberto D.; Carilli, Chris; Casey, Caitlin M.; Decarli, Roberto; Murphy, Eric Joseph; Narayanan, Desika; Walter, Fabian; ngVLA Galaxy Assembly through Cosmic Time Science Working Group, ngVLA Galaxy Ecosystems Science Working Group

    2018-01-01

    The Next Generation Very Large Array (ngVLA) will fundamentally advance our understanding of the formation processes that lead to the assembly of galaxies throughout cosmic history. The combination of large bandwidth with unprecedented sensitivity to the critical low-level CO lines over virtually the entire redshift range will open up the opportunity to conduct large-scale, deep cold molecular gas surveys, mapping the fuel for star formation in galaxies over substantial cosmic volumes. Imaging of the sub-kiloparsec scale distribution and kinematic structure of molecular gas in both normal main-sequence galaxies and large starbursts back to early cosmic epochs will reveal the physical processes responsible for star formation and black hole growth in galaxies over a broad range in redshifts. In the nearby universe, the ngVLA has the capability to survey the structure of the cold, star-forming interstellar medium at parsec-resolution out to the Virgo cluster. A range of molecular tracers will be accessible to map the motion, distribution, and physical and chemical state of the gas as it flows in from the outer disk, assembles into clouds, and experiences feedback due to star formation or accretion into central super-massive black holes. These investigations will crucially complement studies of the star formation and stellar mass histories with the Large UV/Optical/Infrared Surveyor and the Origins Space Telescope, providing the means to obtain a comprehensive picture of galaxy evolution through cosmic times.

  11. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: constraining modified gravity

    Science.gov (United States)

    Mueller, Eva-Maria; Percival, Will; Linder, Eric; Alam, Shadab; Zhao, Gong-Bo; Sánchez, Ariel G.; Beutler, Florian; Brinkmann, Jon

    2018-01-01

    We use baryon acoustic oscillation and redshift space distortion from the completed Baryon Oscillation Spectroscopic Survey, corresponding to data release 12 of the Sloan Digital Sky Survey, combined sample analysis in combination with cosmic microwave background, supernova and redshift space distortion measurements from additional spectroscopic surveys to test deviations from general relativity. We present constraints on several phenomenological models of modified gravity: First, we parametrise the growth of structure using the growth index γ, finding γ = 0.566 ± 0.058 (68% C.L.). Second, we modify the relation of the two Newtonian potentials by introducing two additional parameters, GM and GL. In this approach, GM refers to modifications of the growth of structure whereas GL to modification of the lensing potential. We consider a power law to model the redshift dependency of GM and GL as well as binning in redshift space, introducing four additional degrees of freedom, GM(z 0.5), GL(z 0.5). At 68% C.L. we measure GM = 0.980 ± 0.096 and GL = 1.082 ± 0.060 for a linear model, GM = 1.01 ± 0.36 and GL = 1.31 ± 0.19 for a cubic model as well as GM(z 0.5) = 0.986 ± 0.022, GL(z 0.5) = 1.037 ± 0.029. Thirdly, we investigate general scalar tensor theories of gravity, finding the model to be mostly unconstrained by current data. Assuming a one-parameter f(R) model we can constrain B0 < 7.7 × 10-5 (95% C.L). For all models we considered we find good agreement with general relativity.

  12. Galaxy Disks

    NARCIS (Netherlands)

    van der Kruit, P. C.; Freeman, K. C.

    The disks of disk galaxies contain a substantial fraction of their baryonic matter and angular momentum, and much of the evolutionary activity in these galaxies, such as the formation of stars, spiral arms, bars and rings, and the various forms of secular evolution, takes place in their disks. The

  13. The many lives of active galactic nuclei-II: The formation and evolution of radio jets and their impact on galaxy evolution

    Science.gov (United States)

    Raouf, Mojtaba; Shabala, Stanislav S.; Croton, Darren J.; Khosroshahi, Habib G.; Bernyk, Maksym

    2017-10-01

    We describe new efforts to model radio active galactic nuclei (AGN) in a cosmological context using the Semi-Analytic Galaxy Evolution (SAGE) semi-analytic galaxy model. Our new method tracks the physical properties of radio jets in massive galaxies including the evolution of radio lobes and their impact on the surrounding gas. This model also self consistently follows the gas cooling-heating cycle that significantly shapes star formation and the life and death of many galaxy types. Adding jet physics to SAGE adds new physical properties to the model output, which in turn allows us to make more detailed predictions for the radio AGN population. After calibrating the model to a set of core observations we analyse predictions for jet power, radio cocoon size, radio luminosity and stellar mass. We find that the model is able to match the stellar mass-radio luminosity relation at z ∼ 0 and the radio luminosity function out to z ∼ 1. This updated model will make possible the construction of customised AGN-focused mock survey catalogues to be used for large-scale observing programs.

  14. Constraints on the Evolution of the Galaxy Stellar Mass Function. II. The Quenching Timescale of Galaxies and Its Implication for Their Star Formation Rates

    Science.gov (United States)

    Contini, E.; Kang, X.; Romeo, A. D.; Xia, Q.; Yi, S. K.

    2017-11-01

    We study the connection between the observed star formation rate–stellar mass (SFR–M *) relation and the evolution of the stellar mass function (SMF) by means of a subhalo abundance matching technique coupled to merger trees extracted from an N-body simulation. Our approach consists of forcing the model to match the observed SMF at redshift z∼ 2.3, and letting it evolve down to z∼ 0.3 according to a τ model, an exponentially declining functional form that describes the star formation rate decay of both satellite and central galaxies. In this study, we use three different sets of SMFs: ZFOURGE data from Tomczak et al., UltraVISTA data from Ilbert et al., and COSMOS data from Davidzon et al. We also build a mock survey combining UltraVISTA with ZFOURGE. Our modeling of quenching timescales is consistent with the evolution of the SMF down to z∼ 0.3, with different accuracy depending on the particular survey used for calibration. We tested our model against the observed SMFs at low redshift, and it predicts residuals (observation versus model) within 1σ observed scatter along most of the stellar mass range investigated, and with mean residuals below 0.1 dex in the range ∼ [{10}8.7{--}{10}11.7]{M}ȯ . We then compare the SFR–M * relation predicted by the model with the observed one at different redshifts. The predicted SFR–M * relation underpredicts the median SFR at fixed stellar mass relative to observations at all redshifts. Nevertheless, the shapes are consistent with the observed relations up to intermediate-mass galaxies, followed by a rapid decline for massive galaxies.

  15. Why mammalian lineages respond differently to sexual selection: metabolic rate constrains the evolution of sperm size.

    Science.gov (United States)

    Gomendio, Montserrat; Tourmente, Maximiliano; Roldan, Eduardo R S

    2011-10-22

    The hypothesis that sperm competition should favour increases in sperm size, because it results in faster swimming speeds, has received support from studies on many taxa, but remains contentious for mammals. We suggest that this may be because mammalian lineages respond differently to sexual selection, owing to major differences in body size, which are associated with differences in mass-specific metabolic rate. Recent evidence suggests that cellular metabolic rate also scales with body size, so that small mammals have cells that process energy and resources from the environment at a faster rate. We develop the 'metabolic rate constraint hypothesis' which proposes that low mass-specific metabolic rate among large mammals may limit their ability to respond to sexual selection by increasing sperm size, while this constraint does not exist among small mammals. Here we show that among rodents, which have high mass-specific metabolic rates, sperm size increases under sperm competition, reaching the longest sperm sizes found in eutherian mammals. By contrast, mammalian lineages with large body sizes have small sperm, and while metabolic rate (corrected for body size) influences sperm size, sperm competition levels do not. When all eutherian mammals are analysed jointly, our results suggest that as mass-specific metabolic rate increases, so does maximum sperm size. In addition, species with low mass-specific metabolic rates produce uniformly small sperm, while species with high mass-specific metabolic rates produce a wide range of sperm sizes. These findings support the hypothesis that mass-specific metabolic rates determine the budget available for sperm production: at high levels, sperm size increases in response to sexual selection, while low levels constrain the ability to respond to sexual selection by increasing sperm size. Thus, adaptive and costly traits, such as sperm size, may only evolve under sexual selection when metabolic rate does not constrain cellular

  16. CONSTRAINED EVOLUTION OF A RADIALLY MAGNETIZED PROTOPLANETARY DISK: IMPLICATIONS FOR PLANETARY MIGRATION

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Matthew [Department of Physics, University of Toronto, 60 St. George St., Toronto, ON M5S 1A7 (Canada); Thompson, Christopher [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada)

    2015-12-10

    We consider the inner ∼1 AU of a protoplanetary disk (PPD) at a stage where angular momentum transport is driven by the mixing of a radial magnetic field into the disk from a T Tauri wind. Because the radial profile of the imposed magnetic field is well constrained, a constrained calculation of the disk mass flow becomes possible. The vertical disk profiles obtained in Paper I imply a stronger magnetization in the inner disk, faster accretion, and a secular depletion of the disk material. Inward transport of solids allows the disk to maintain a broad optical absorption layer even when the grain abundance becomes too small to suppress its ionization. Thus, a PPD may show a strong mid- to near-infrared spectral excess even while its mass profile departs radically from the minimum-mass solar nebula. The disk surface density is buffered at ∼30 g cm{sup −2}; below this, X-rays trigger magnetorotational turbulence at the midplane strong enough to loft millimeter- to centimeter-sized particles high in the disk, followed by catastrophic fragmentation. A sharp density gradient bounds the inner depleted disk and propagates outward to ∼1–2 AU over a few megayears. Earth-mass planets migrate through the inner disk over a similar timescale, whereas the migration of Jupiters is limited by the supply of gas. Gas-mediated migration must stall outside 0.04 AU, where silicates are sublimated and the disk shifts to a much lower column. A transition disk emerges when the dust/gas ratio in the MRI-active layer falls below X{sub d} ∼ 10{sup −6} (a{sub d}/μm), where a{sub d} is the grain size.

  17. Constraining red-shift parametrization parameters in Brans-Dicke theory: evolution of open confidence contours

    Science.gov (United States)

    Biswas, Ritabrata; Debnath, Ujjal

    2014-10-01

    In Brans-Dicke theory of gravity, from the nature of the scalar field-potential considered, the dark energy, dark matter, radiation densities predicted by different observations and the closedness of the universe considered, we can fix our ω BD , the Brans-Dicke parameter, keeping only the thing in mind that from different solar system constrains it must be greater than 5×105. Once we have a value, satisfying the required lower boundary, in our hand we proceed for setting unknown parameters of the different dark energy models' EoS parameter. In this paper we work with three well known red shift parametrizations of dark energy EoS. To constrain their free parameters for Brans Dicke theory of gravity we take twelve point red shift vs Hubble's parameter data and perform χ 2 test. We present the observational data analysis mechanism for Stern, Stern+BAO and Stern+BAO+CMB observations. Minimising χ 2, we obtain the best fit values and draw different confidence contours. We analyze the contours physically. Also we examine the best fit of distance modulus for our theoretical models and the Supernovae Type Ia Union2 sample. For Brans Dicke theory of gravity the difference from the mainstream confidence contouring method of data analysis id that the confidence contours evolved are not at all closed contours like a circle or a ellipse. Rather they are found to be open contours allowing the free parameters to float inside a infinite region of parameter space. However, negative EoSs are likely to evolve from the best fit values.

  18. Nearby galaxies as pointers to a better theory of cosmic evolution.

    Science.gov (United States)

    Peebles, P J E; Nusser, Adi

    2010-06-03

    The great advances in the network of cosmological tests show that the relativistic Big Bang theory is a good description of our expanding Universe. However, the properties of nearby galaxies that can be observed in greatest detail suggest that a better theory would describe a mechanism by which matter is more rapidly gathered into galaxies and groups of galaxies. This more rapid growth occurs in some theoretical ideas now under discussion.

  19. Star Clusters as Tracers of the Evolution of Local Group Galaxies

    Science.gov (United States)

    Grebel, Eva K.

    2015-08-01

    Only 12 of the more than 76 Local Group galaxies contain old globular clusters. These galaxies show a surprisingly large range of globular cluster specific frequencies. It is unclear why the specific frequencies vary widely even among galaxies of the same type and comparable luminosity. Many of the host galaxies contain ancient globulars, but in some globular cluster formation may have been delayed by a few Gyr. There is growing evidence for light element abundance variations also in extragalactic globular clusters, supporting the case for multiple stellar populations. The distribution of globular clusters in Local Group galaxies often reveals radial metallicity gradients. Also, remote globular clusters tend to be more extended and diffuse. There is ample direct and indirect evidence for globular cluster accretion from dwarf galaxies onto more massive galaxies, although too simplistic interpretations should be avoided. The spatial distribution of globular clusters in dwarf galaxies seems to support cored dark matter halos. Younger star clusters, including both open and populous clusters, are found in a much wider range of Local Group galaxies and can serve as valuable tracers of their star formation histories over cosmic time, complementing but not always following field star formation histories. In this review, some of the key properties of Local Group star clusters will be summarized.

  20. Constraints on the dynamical evolution of the galaxy group M81

    Science.gov (United States)

    Oehm, W.; Thies, I.; Kroupa, P.

    2017-05-01

    According to the standard model of cosmology, galaxies are embedded in dark matter haloes that are made of particles beyond the standard model of particle physics, thus extending the mass and the size of the visible baryonic matter by typically two orders of magnitude. The observed gas distribution throughout the nearby M81 group of galaxies shows evidence for past significant galaxy-galaxy interactions but without a merger between the present-day members having occurred. This group is here studied for possible dynamical solutions within the dark matter standard model. In order to cover a comprehensive set of initial conditions, the inner three core members M81, M82 and NGC 3077 are treated as a three-body model based on Navarro-Frenk-White profiles. The possible orbits of these galaxies are examined statistically taking into account dynamical friction. Long living, non-merging initial constellations that allow multiple galaxy-galaxy encounters comprise unbound galaxies only, which are arriving from a far distance and happen to simultaneously encounter each other within the recent 500 Myr. Our results are derived by the employment of two separate and independent statistical methods, namely a Markov chain Monte Carlo method and the genetic algorithm using the sap system environment. The conclusions reached are confirmed by high-resolution simulations of live self-consistent systems (N-body calculations). Given the observed positions of the three galaxies, the solutions found comprise predictions for their proper motions.

  1. Feedback and Feeding in the Context of Galaxy Evolution with SPICA: Direct Characterisation of Molecular Outflows and Inflows

    Science.gov (United States)

    González-Alfonso, E.; Armus, L.; Carrera, F. J.; Charmandaris, V.; Efstathiou, A.; Egami, E.; Fernández-Ontiveros, J. A.; Fischer, J.; Granato, G. L.; Gruppioni, C.; Hatziminaoglou, E.; Imanishi, M.; Isobe, N.; Kaneda, H.; Koziel-Wierzbowska, D.; Malkan, M. A.; Martín-Pintado, J.; Mateos, S.; Matsuhara, H.; Miniutti, G.; Nakagawa, T.; Pozzi, F.; Rico-Villas, F.; Rodighiero, G.; Roelfsema, P.; Spinoglio, L.; Spoon, H. W. W.; Sturm, E.; van der Tak, F.; Vignali, C.; Wang, L.

    2017-11-01

    A far-infrared observatory such as the SPace Infrared telescope for Cosmology and Astrophysics, with its unprecedented spectroscopic sensitivity, would unveil the role of feedback in galaxy evolution during the last 10 Gyr of the Universe (z = 1.5-2), through the use of far- and mid-infrared molecular and ionic fine structure lines that trace outflowing and infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni line shapes and absorption blueshifted wings in molecular lines with high dipolar moments, and through emission line wings of fine-structure lines of ionised gas. We quantify the detectability of galaxy-scale massive molecular and ionised outflows as a function of redshift in AGN-dominated, starburst-dominated, and main-sequence galaxies, explore the detectability of metal-rich inflows in the local Universe, and describe the most significant synergies with other current and future observatories that will measure feedback in galaxies via complementary tracers at other wavelengths.

  2. Do You See What I See? Exploring the Consequences of Luminosity Limits in Black Hole–Galaxy Evolution Studies

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Mackenzie L.; Hickox, Ryan C.; DiPompeo, Michael A. [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Mutch, Simon J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Croton, Darren J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Ptak, Andrew F. [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)

    2017-07-10

    In studies of the connection between active galactic nuclei (AGNs) and their host galaxies, there is widespread disagreement on some key aspects of the connection. These disagreements largely stem from a lack of understanding of the nature of the full underlying AGN population. Recent attempts to probe this connection utilize both observations and simulations to correct for a missed population, but presently are limited by intrinsic biases and complicated models. We take a simple simulation for galaxy evolution and add a new prescription for AGN activity to connect galaxy growth to dark matter halo properties and AGN activity to star formation. We explicitly model selection effects to produce an “observed” AGN population for comparison with observations and empirically motivated models of the local universe. This allows us to bypass the difficulties inherent in models that attempt to infer the AGN population by inverting selection effects. We investigate the impact of selecting AGNs based on thresholds in luminosity or Eddington ratio on the “observed” AGN population. By limiting our model AGN sample in luminosity, we are able to recreate the observed local AGN luminosity function and specific star formation-stellar mass distribution, and show that using an Eddington ratio threshold introduces less bias into the sample by selecting the full range of growing black holes, despite the challenge of selecting low-mass black holes. We find that selecting AGNs using these various thresholds yield samples with different AGN host galaxy properties.

  3. Evolution of Star Formation and H I Gas Content in Galaxy Groups

    NARCIS (Netherlands)

    Birenbaum, Adam; Hess, K. M.; Wilcots, E. M.

    We present an analysis of the neutral hydrogen gas (H I) content, star formation histories, and distribution of galaxies in groups as a function of their parent halo mass. The Arecibo Legacy Fast ALFA survey α.40 data release allows us to study the H I properties of 742 galaxy groups in the volume

  4. Evolution since z=0.5 of the morphology-density relation for clusters of galaxies

    NARCIS (Netherlands)

    Dressler, A; Oemler, A; Couch, WJ; Smail, [No Value; Ellis, RS; Barger, A; Butcher, H; Poggianti, BM; Sharples, RM

    1997-01-01

    Using traditional morphological classifications of galaxies in 10 intermediate-redshift (z similar to 0.5) clusters observed with WFPC2 on the Hubble Space Telescope, we derive relations between morphology and local galaxy density similar to that found by Dressier for low-redshift clusters. Taken

  5. The evolution of the atomic and molecular interstellar medium in star-forming galaxies

    NARCIS (Netherlands)

    Popping, Gergö

    2014-01-01

    In this thesis I developed models to make predictions for the atomic and molecular gas content of galaxies. Main results of my thesis include that the atomic hydrogen content of galaxies remained relatively constant with over the last 10 Billion years, whereas the molecular hydrogen content

  6. Evolution of the Distribution of Neutron Exposures in the Galaxy Disc ...

    Indian Academy of Sciences (India)

    In this work, based on the analytical model with delayed production approximation developed by Pagel & Tautvaišienė (1995) for the Galaxy, the analytic solutions of the distribution of neutron exposures of the Galaxy (hereafter NEG) are obtained. The present results appear to reasonably reproduce the distribution of ...

  7. Adaptive Differential Evolution Approach for Constrained Economic Power Dispatch with Prohibited Operating Zones

    Directory of Open Access Journals (Sweden)

    Abdellatif HAMOUDA

    2011-12-01

    Full Text Available Economic power dispatch (EPD is one of the main tools for optimal operation and planning of modern power systems. To solve effectively the EPD problem, most of the conventional calculus methods rely on the assumption that the fuel cost characteristic of a generating unit is a continuous and convex function, resulting in inaccurate dispatch. This paper presents the design and application of efficient adaptive differential evolution (ADE algorithm for the solution of the economic power dispatch problem, where the non-convex characteristics of the generators, such us prohibited operating zones and ramp rate limits of the practical generator operation are considered. The 26 bus benchmark test system with 6 units having prohibited operating zones and ramp rate limits was used for testing and validation purposes. The results obtained demonstrate the effectiveness of the proposed method for solving the non-convex economic dispatch problem.

  8. H0LiCOW VII: cosmic evolution of the correlation between black hole mass and host galaxy luminosity

    Science.gov (United States)

    Ding, Xuheng; Treu, Tommaso; Suyu, Sherry H.; Wong, Kenneth C.; Morishita, Takahiro; Park, Daeseong; Sluse, Dominique; Auger, Matthew W.; Agnello, Adriano; Bennert, Vardha N.; Collett, Thomas E.

    2017-11-01

    Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH) and their host galaxy luminosity (Lhost). We demonstrate the power of lensing by analysing two systems for which state-of-the-art lens modelling techniques have been applied to deep Hubble Space Telescope imaging data. We use (i) the reconstructed images to infer the total and bulge luminosity of the host and (ii) published broad-line spectroscopy to estimate M_BH using the so-called virial method. We then enlarge our sample with new calibration of previously published measurements to study the evolution of the correlation out to z ∼ 4.5. Consistent with previous work, we find that without taking into account passive luminosity evolution, the data points lie on the local relation. Once the passive luminosity evolution is taken into account, we find that black holes in the more distant Universe reside in less luminous galaxies than today. Fitting this offset as M_BH/Lhost ∝ (1 + z)γ, and taking into account selection effects, we obtain γ = 0.6 ± 0.1 and 0.8 ± 0.1 for the case of M_BH-Lbulge and M_BH-Ltotal, respectively. To test for systematic uncertainties and selection effects we also consider a reduced sample that is homogeneous in data quality. We find consistent results but with considerably larger uncertainty due to the more limited sample size and redshift coverage (γ = 0.7 ± 0.4 and 0.2 ± 0.5 for M_BH-Lbulge and M_BH-Ltotal, respectively), highlighting the need to gather more high-quality data for high-redshift lensed quasar hosts. Our result is consistent with a scenario where the growth of the black hole predates that of the host galaxy.

  9. Revealing structure and evolution within the corona of the Seyfert galaxy I Zw 1

    Science.gov (United States)

    Wilkins, D. R.; Gallo, L. C.; Silva, C. V.; Costantini, E.; Brandt, W. N.; Kriss, G. A.

    2017-11-01

    X-ray spectral timing analysis is presented of XMM-Newton observations of the narrow-line Seyfert 1 galaxy I Zwicky 1 taken in 2015 January. After exploring the effect of background flaring on timing analyses, X-ray time lags between the reflection-dominated 0.3-1.0 keV energy and continuum-dominated 1.0-4.0 keV band are measured, indicative of reverberation off the inner accretion disc. The reverberation lag time is seen to vary as a step function in frequency; across lower frequency components of the variability, 3 × 10-4-1.2 × 10-3 Hz a lag of 160 s is measured, but the lag shortens to (59 ± 4) s above 1.2 × 10-3 Hz. The lag-energy spectrum reveals differing profiles between these ranges with a change in the dip showing the earliest arriving photons. The low-frequency signal indicates reverberation of X-rays emitted from a corona extended at low height over the disc, while at high frequencies, variability is generated in a collimated core of the corona through which luminosity fluctuations propagate upwards. Principal component analysis of the variability supports this interpretation, showing uncorrelated variation in the spectral slope of two power-law continuum components. The distinct evolution of the two components of the corona is seen as a flare passes inwards from the extended to the collimated portion. An increase in variability in the extended corona was found preceding the initial increase in X-ray flux. Variability from the extended corona was seen to die away as the flare passed into the collimated core leading to a second sharper increase in the X-ray count rate.

  10. A Conference on the Origin (and Evolution of Baryonic Galaxy Halos

    Directory of Open Access Journals (Sweden)

    Duncan Forbes

    2017-05-01

    Full Text Available A conference was held in March 2017 in the Galapagos Islands on the topic of The Origin (and Evolution of Baryonic Galaxy Halos. It attracted some 120 researchers from around the world. They presented 68 talks (nine of which were invited and 30 posters over five days. A novel element of the talk schedule was that participants were asked which talks they wanted to hear and the schedule was made up based on their votes and those of the Scientific Organizing Committee SOC . The final talk schedule had 34% of the talks given by women. An emphasis was given to discussion time directly after each talk. Combined with limited/no access to the internet, this resulted in high level of engagement and lively discussions. A prize was given to the poster voted the best by participants. A free afternoon included organized excursions to see the local scenery and wildlife of the Galapagos (e.g., the giant tortoises. Four public talks were given, in Spanish, for the local residents of the town. A post-conference survey was conducted, with most participants agreeing that the conference met their scientific needs and helped to initiate new research directions. Although it was challenging to organize such a large international meeting in such an isolated location as the Galapagos Islands (and much credit goes to the Local Organizing Committee LOC and staff of Quito Astronomical Observatory for their logistical efforts, organizing the meeting for over a year, it was very much a successful conference. We hope it will play a small part in further developing astronomy in Ecuador.

  11. THE COMPARATIVE CHEMICAL EVOLUTION OF AN ISOLATED DWARF GALAXY: A VLT AND KECK SPECTROSCOPIC SURVEY OF WLM

    Energy Technology Data Exchange (ETDEWEB)

    Leaman, Ryan; Venn, Kim A.; Mendel, J. Trevor [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1 (Canada); Brooks, Alyson M. [California Institute of Technology, M/C 350-17, Pasadena, CA 91125 (United States); Battaglia, Giuseppina [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Cole, Andrew A. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, TAS (Australia); Ibata, Rodrigo A. [Observatoire Astronomique, Universite de Strasbourg, CNRS, 11 rue de l' Universite, F-67000 Strasbourg (France); Irwin, Mike J. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); McConnachie, Alan W. [National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria BC V9E 2E7 (Canada); Starkenburg, Else; Tolstoy, Eline, E-mail: rleaman@iac.es [Kapteyn Institute, University of Groningen, Postbus 800, 9700 AV Groningen (Netherlands)

    2013-04-20

    Building on our previous spectroscopic and photometric analysis of the isolated Local Group dwarf irregular (dIrr) galaxy WLM, we present a comparison of the metallicities of its red giant branch stars with respect to the well-studied Local Group dwarf spheroidal galaxies (dSphs) and Magellanic Clouds. We calculate a mean metallicity of [Fe/H] =-1.28 {+-} 0.02 and an intrinsic spread in metallicity of {sigma} = 0.38 {+-} 0.04 dex, similar to the mean and spread observed in the massive dSph Fornax and the Small Magellanic Cloud. Thus, despite WLM's isolated environment, its global metallicity still follows expectations for mass and its global chemical evolution is similar to other nearby luminous dwarf galaxies (gas-rich or gas-poor). The data also show a radial gradient in [Fe/H] of d[Fe/H]/dr{sub c} = -0.04 {+-} 0.04 dex r{sub c}{sup -1}, which is flatter than that seen in the unbiased and spatially extended surveys of dSphs. Comparison of the spatial distribution of [Fe/H] in WLM, the Magellanic Clouds, and a sample of Local Group dSphs shows an apparent dichotomy in the sense that the dIrrs have statistically flatter radial [Fe/H] gradients than the low angular momentum dSphs. The correlation between angular momentum and radial metallicity gradient is further supported when considering the Local Group dEs. This chemodynamic relationship offers a new and useful constraint for environment-driven dwarf galaxy evolution models in the Local Group.

  12. An Empirically-Calibrated Model For Interpreting the Evolution of Galaxies During the Reionization Era

    OpenAIRE

    Stark, Daniel P.; Loeb, Abraham; Ellis, Richard S.

    2007-01-01

    [Abridged] We develop a simple star formation model whose goal is to interpret the emerging body of observational data on star-forming galaxies at z>~6. The efficiency and duty cycle of the star formation activity within dark matter halos are determined by fitting the luminosity functions of Lya emitter and Lyman-break galaxies at redshifts z~5-6. Using our model parameters we predict the likely abundance of star forming galaxies at earlier epochs and compare these to the emerging data in the...

  13. Ultra-diffuse galaxies outside clusters: clues to their formation and evolution

    Science.gov (United States)

    Román, Javier; Trujillo, Ignacio

    2017-07-01

    We identify six ultra-diffuse galaxies (UDGs) outside clusters in three nearby isolated groups (0.014 250 kpc) of our three groups, we identify a population of potential UDG progenitors (two of them confirmed spectroscopically). These progenitors have similar masses, shapes and sizes but are bluer, g - I ˜ 0.45 [and for this reason brighter, μg(0) 24 mag arcsec-2] UDGs after ˜6 Gyr. If confirmed, our observations support a scenario where UDGs are old, extended, low surface brightness dwarf galaxies (M⋆ ˜ 108 M⊙) born in the field, are later processed in groups and, ultimately, infall into galaxy clusters by group accretion.

  14. Stellar mass distribution of S4G disk galaxies and signatures of bar-induced secular evolution

    Science.gov (United States)

    Díaz-García, S.; Salo, H.; Laurikainen, E.

    2016-12-01

    ) in bins of M∗ and T. We find evidence for bar-induced secular evolution of disk galaxies in terms of disk spreading and enhanced central mass concentration. We also obtain average bars (2D), and we show that bars hosted by early-type galaxies are more centrally concentrated and have larger density amplitudes than their late-type counterparts. The FITS files of the synthetic images and the tabulated radial profiles of the mean (and dispersion of) stellar mass density, 3.6 μm surface brightness, Fourier amplitudes, gravitational force, and the stellar contribution to the circular velocity are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A84

  15. Constraining the baryon-dark matter relative velocity with the large-scale three-point correlation function of the SDSS BOSS DR12 CMASS galaxies

    Science.gov (United States)

    Slepian, Zachary; Eisenstein, Daniel J.; Blazek, Jonathan A.; Brownstein, Joel R.; Chuang, Chia-Hsun; Gil-Marín, Héctor; Ho, Shirley; Kitaura, Francisco-Shu; McEwen, Joseph E.; Percival, Will J.; Ross, Ashley J.; Rossi, Graziano; Seo, Hee-Jong; Slosar, Anže; Vargas-Magaña, Mariana

    2018-02-01

    We search for a galaxy clustering bias due to a modulation of galaxy number with the baryon-dark matter relative velocity resulting from recombination-era physics. We find no detected signal and place the constraint bv Dark Energy Spectroscopic Instrument (DESI) to self-protect against the relative velocity as a possible systematic.

  16. Joint analysis of galaxy-galaxy lensing and galaxy clustering: Methodology and forecasts for Dark Energy Survey

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.; Krause, E.; Dodelson, S.; Jain, B.; Amara, A.; Becker, M. R.; Bridle, S. L.; Clampitt, J.; Crocce, M.; Fosalba, P.; Gaztanaga, E.; Honscheid, K.; Rozo, E.; Sobreira, F.; Sánchez, C.; Wechsler, R. H.; Abbott, T.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Fausti Neto, A.; Fernandez, E.; Finley, D. A.; Flaugher, B.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; James, D. J.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Miller, C. J.; Miquel, R.; Nichol, R. C.; Ogando, R.; Plazas, A. A.; Roe, N.; Romer, A. K.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Vikram, V.; Walker, A. R.; Weller, J.; Zuntz, J.

    2016-09-30

    The joint analysis of galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth function of large scale structure. Our analysis will be carried out on data from the Dark Energy Survey (DES), with its measurements of both the distribution of galaxies and the tangential shears of background galaxies induced by these foreground lenses. We develop a practical approach to modeling the assumptions and systematic effects affecting small scale lensing, which provides halo masses, and large scale galaxy clustering. Introducing parameters that characterize the halo occupation distribution (HOD), photometric redshift uncertainties, and shear measurement errors, we study how external priors on different subsets of these parameters affect our growth constraints. Degeneracies within the HOD model, as well as between the HOD and the growth function, are identified as the dominant source of complication, with other systematic effects sub-dominant. The impact of HOD parameters and their degeneracies necessitate the detailed joint modeling of the galaxy sample that we employ. Finally, we conclude that DES data will provide powerful constraints on the evolution of structure growth in the universe, conservatively/optimistically constraining the growth function to 7.9%/4.8% with its first-year data that covered over 1000 square degrees, and to 3.9%/2.3% with its full five-year data that will survey 5000 square degrees, including both statistical and systematic uncertainties.

  17. AGN-host connection at 0.5 < z < 2.5: A rapid evolution of AGN fraction in red galaxies during the last 10 Gyr

    Science.gov (United States)

    Wang, Tao; Elbaz, D.; Alexander, D. M.; Xue, Y. Q.; Gabor, J. M.; Juneau, S.; Schreiber, C.; Zheng, X.-Z.; Wuyts, S.; Shi, Y.; Daddi, E.; Shu, X.-W.; Fang, G.-W.; Huang, J.-S.; Luo, B.; Gu, Q.-S.

    2017-05-01

    We explore the dependence of the incidence of moderate-luminosity (L0.5-8 keV = 1041.9-43.7 erg s-1) active galactic nuclei (AGNs) and the distribution of their accretion rates on host color at 0.5 mass-complete parent galaxy sample down to M∗ > 1010 M⊙. We use extinction-corrected rest-frame U-V colors to divide both AGN hosts and non-AGN galaxies into red sequence (red), green valley (green), and blue cloud (blue) populations. We find that the fraction of galaxies hosting an AGN at fixed X-ray luminosity increases with stellar mass and redshift for all the three galaxy populations, independent of their colors. However, both the AGN fraction at fixed stellar mass and its evolution with redshift are clearly dependent on host colors. Most notably, red galaxies have the lowest AGN fraction ( 5%) at z 1 yet with most rapid evolution with redshift, increasing by a factor of 5 (24%) at z 2. Green galaxies exhibit the highest AGN fraction across all redshifts, which is most pronounced at z 2 with more than half of them hosting an AGN at M∗ > 1010.6 M⊙. Together with the high AGN fraction in red galaxies at z 2, this indicates that (X-ray) AGNs could be important in both transforming (quenching) star-forming galaxies into quiescent ones and subsequently maintaining their quiescence at high redshift. Furthermore, consistent with previous studies at lower redshifts, we show that the probability of hosting an AGN for the total galaxy population can be characterized by a universal Eddington ratio (as approximated by LX/M∗) distribution (p(λEdd) λEdd-0.4), which is independent on host mass. Yet consistent with their different AGN fractions, galaxies with different colors appear to also have different p(λEdd) with red galaxies exhibiting more rapid redshift evolution compared with that for green and blue galaxies. Evidence for a steeper power-law distribution of p(λEdd) in red galaxies (p(λEdd) λEdd-0.6) is also presented, though larger samples are needed to

  18. Out-of-equilibrium evolution of kinetically constrained many-body quantum systems under purely dissipative dynamics.

    Science.gov (United States)

    Olmos, Beatriz; Lesanovsky, Igor; Garrahan, Juan P

    2014-10-01

    We explore the relaxation dynamics of quantum many-body systems that undergo purely dissipative dynamics through non-classical jump operators that can establish quantum coherence. Our goal is to shed light on the differences in the relaxation dynamics that arise in comparison to systems evolving via classical rate equations. In particular, we focus on a scenario where both quantum and classical dissipative evolution lead to a stationary state with the same values of diagonal or "classical" observables. As a basis for illustrating our ideas we use spin systems whose dynamics becomes correlated and complex due to dynamical constraints, inspired by kinetically constrained models (KCMs) of classical glasses. We show that in the quantum case the relaxation can be orders of magnitude slower than the classical one due to the presence of quantum coherences. Aspects of these idealized quantum KCMs become manifest in a strongly interacting Rydberg gas under electromagnetically induced transparency (EIT) conditions in an appropriate limit. Beyond revealing a link between this Rydberg gas and the rather abstract dissipative KCMs of quantum glassy systems, our study sheds light on the limitations of the use of classical rate equations for capturing the non-equilibrium behavior of this many-body system.

  19. A Wide-field Study of the z 0.8 Cluster RX J0152.7-1357: The Role of Environment in Galaxy Evolution

    Science.gov (United States)

    Patel, Shannon; Kelson, D. D.; Holden, B. P.; Illingworth, G. D.; Franx, M.; van der Wel, A.; Ford, H.

    2009-01-01

    We study the influence of local environment on the formation and evolution of galaxies in the z 0.8 galaxy cluster RX J0152.7-1357 (RXJ0152-13) and its outskirts. Simulations show that massive clusters like RXJ0152-13 will grow in mass by a factor of 2-3 by z=0 through accretion of infalling galaxies and groups of galaxies. Our goal is to understand the transformation process that changes these infalling galaxies into red, early-type cluster members. We used a low-dispersion prism in the IMACS spectrograph at Magellan to obtain low-resolution spectroscopy for large numbers of galaxies over a wide field (D 30') in order to identify members in the vicinity of the cluster. With a mass limited sample (M>4x1010 MSun), we examined the rest-frame colors of galaxies as a function of local projected galaxy density. We found that the high-density regions in the core of the cluster and in the infalling groups support a high fraction of red galaxies compared to the lower density regions, as others have found at lower redshift. Intermediate density regions also revealed an elevated fraction of red galaxies. We also studied the star formation rates (SFRs) of members using Spitzer MIPS 24µm flux as a tracer. Our initial results show a lack of star-forming galaxies in the core of the cluster and in the high-density regions of the groups in the outskirts, which is consistent with their red colors discussed above. These results suggest that many future cluster members are transformed into passively evolving, red, early-types in infalling groups and in the surrounding filamentary structure of the cluster.

  20. Emission-Line Galaxies from the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) Grism Survey. I. The South Fields

    Science.gov (United States)

    Straughn, Amber N.; Pirzkal, Norbert; Meurer, Gerhardt R.; Cohen, Seth H.; Windhorst, Rogier A.; Malhotra, Sangeeta; Rhoads, James; Gardner, Jonathan P.; Hathi, Nimish P.; Jansen, Rolf A.; Grogin, Norman; Panagia, Nino; di Serego Alighieri, Sperello; Gronwall, Caryl; Walsh, Jeremy; Pasquali, Anna; Xu, Chun

    2009-10-01

    We present results of a search for emission-line galaxies (ELGs) in the southern fields of the Hubble Space Telescope Probing Evolution And Reionization Spectroscopically (PEARS) grism survey. The PEARS South Fields consist of five Advanced Camera for Surveys pointings (including the Hubble Ultra Deep Field) with the G800L grism for a total of 120 orbits, revealing thousands of faint object spectra in the GOODS-South region of the sky. ELGs are one subset of objects that are prevalent among the grism spectra. Using a two-dimensional detection and extraction procedure, we find 320 emission lines originating from 226 galaxy "knots" within 192 individual galaxies. Line identification results in 118 new grism-spectroscopic redshifts for galaxies in the GOODS-South Field. We measure emission-line fluxes using standard Gaussian fitting techniques. At the resolution of the grism data, the Hβ and [O III] doublet are blended. However, by fitting two Gaussian components to the Hβ and [O III] features, we find that many of the PEARS ELGs have high [O III]/Hβ ratios compared to other galaxy samples of comparable luminosities. The star formation rates of the ELGs are presented, as well as a sample of distinct giant star-forming regions at z ~ 0.1-0.5 across individual galaxies. We find that the radial distances of these H II regions in general reside near the galaxies' optical continuum half-light radii, similar to those of giant H II regions in local galaxies.

  1. Submillimeter Observations of CLASH 2882 and the Evolution of Dust in this Galaxy

    Science.gov (United States)

    Dwek, Eli; Staguhn, Johannes; Arendt, Richard G; Kovacs, Attila; Decarli, Roberto; Egami, Eiichi; Michalowski, Michal J.; Rawle, Timothy D.; Toft, Sune; Walter, Fabian

    2015-01-01

    Two millimeter observations of the MACS J1149.6+2223 cluster have detected a source that was consistent with the location of the lensed MACS 1149-JD galaxy at z = 9.6. A positive identification would have rendered this galaxy as the youngest dust forming galaxy in the universe. Follow up observation with the AzTEC 1.1 mm camera and the IRAM NOrthern Extended Millimeter Array (NOEMA) at 1.3 mm have not confirmed this association. In this paper we show that the NOEMA observations associate the 2 mm source with [PCB2012] 2882,12 source number 2882 in the Cluster Lensing And Supernova survey with Hubble (CLASH) catalog of MACS J1149.6 +2223. This source, hereafter referred to as CLASH 2882, is a gravitationally lensed spiral galaxy at z = 0.99. We combine the Goddard IRAM Superconducting 2-Millimeter Observer (GISMO) 2 mm and NOEMA 1.3 mm fluxes with other (rest frame) UV to far-IR observations to construct the full spectral energy distribution of this galaxy, and derive its star formation history, and stellar and interstellar dust content. The current star formation rate of the galaxy is 54/mu/Solar Mass/yr, and its dust mass is about 5 × 10(exp 7)/mu Solar Mass, where mu is the lensing magnification factor for this source, which has a mean value of 2.7. The inferred dust mass is higher than the maximum dust mass that can be produced by core collapse supernovae and evolved AGB stars. As with many other star forming galaxies, most of the dust mass in CLASH 2882 must have been accreted in the dense phases of the interstellar medium.

  2. Black Hole Growth in Disk Galaxies Mediated by the Secular Evolution of Short Bars

    Science.gov (United States)

    Du, Min; Debattista, Victor P.; Shen, Juntai; Ho, Luis C.; Erwin, Peter

    2017-08-01

    The growth of black holes (BHs) in disk galaxies lacking classical bulges, which implies an absence of significant mergers, appears to be driven by secular processes. Short bars of sub-kiloparsec radius have been hypothesized to be an important mechanism for driving gas inflows to small scale, feeding central BHs. In order to quantify the maximum BH mass allowed by this mechanism, we examine the robustness of short bars to the dynamical influence of BHs. Large-scale bars are expected to be robust, long-lived structures; extremely massive BHs, which are rare, are needed to completely destroy such bars. However, we find that short bars, which are generally embedded in large-scale outer bars, can be destroyed quickly when BHs of mass {M}{bh}˜ 0.05 % {--}0.2 % of the total stellar mass ({M}\\star ) are present. In agreement with this prediction, all galaxies observed to host short bars have BHs with a mass fraction less than 0.2 % {M}\\star . Thus, the dissolution of short inner bars is possible, perhaps even frequent, in the universe. An important implication of this result is that inner-bar-driven gas inflows may be terminated when BHs grow to ˜ 0.1 % {M}\\star . We predict that 0.2 % {M}\\star is the maximum mass of BHs allowed if they are fed predominately via inner bars. This value matches well the maximum ratio of BH-to-host-galaxy stellar mass observed in galaxies with pseudo-bulges and most nearby active galactic nucleus host galaxies. This hypothesis provides a novel explanation for the lower {M}{bh}/{M}\\star in galaxies that have avoided significant mergers compared with galaxies with classical bulges.

  3. CONNECTING THE GAMMA RAY BURST RATE AND THE COSMIC STAR FORMATION HISTORY: IMPLICATIONS FOR REIONIZATION AND GALAXY EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Brant E.; Ellis, Richard S., E-mail: brant@astro.caltech.edu [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

    2012-01-10

    The contemporary discoveries of galaxies and gamma ray bursts (GRBs) at high redshift have supplied the first direct information on star formation when the universe was only a few hundred million years old. The probable origin of long duration GRBs in the deaths of massive stars would link the universal GRB rate to the redshift-dependent star formation rate (SFR) density, although exactly how is currently unknown. As the most distant GRBs and star-forming galaxies probe the reionization epoch, the potential reward of understanding the redshift-dependent ratio {Psi}(z) of the GRB rate to SFR is significant and includes addressing fundamental questions such as incompleteness in rest-frame UV surveys for determining the SFR at high redshift and time variations in the stellar initial mass function. Using an extensive sample of 112 GRBs above a fixed luminosity limit drawn from the Second Swift Burst Alert Telescope catalog and accounting for uncertainty in their redshift distribution by considering the contribution of 'dark' GRBs, we compare the cumulative redshift distribution N(< z) of GRBs with the star formation density {rho}-dot{sub *}(z) measured from UV-selected galaxies over 0 < z <4. Strong evolution (e.g., {Psi}(z){proportional_to}(1 + z){sup 1.5}) is disfavored (Kolmogorov-Smirnov test P < 0.07). We show that more modest evolution (e.g., {Psi}(z){proportional_to}(1 + z){sup 0.5}) is consistent with the data (P Almost-Equal-To 0.9) and can be readily explained if GRBs occur primarily in low-metallicity galaxies which are proportionally more numerous at earlier times. If such trends continue beyond z {approx_equal} 4, we find that the discovery rate of distant GRBs implies an SFR density much higher than that inferred from UV-selected galaxies. While some previous studies of the GRB-SFR connection have concluded that GRB-inferred star formation at high redshift would be sufficient to maintain cosmic reionization over 6

  4. The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years

    Science.gov (United States)

    Finkelstein, Steven L.; Ryan, Russell E., Jr.; Papovich, Casey; Dickinson, Mark; Song, Mimi; Somerville, Rachel; Ferguson, Henry C.; Salmon, Brett; Giavalisco, Mauro; Koekomoer, Anton M.; hide

    2014-01-01

    We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity function at z = 4 to 8. We use deep Hubble Space Telescope imaging over the CANDELS/GOODS fields, the Hubble Ultra Deep Field and the Hubble Frontier Field deep parallel observations near the Abell 2744 and MACS J0416.1- 2403 clusters. The combination of these surveys provides an effective volume of 0.6-1.2 ×10(exp 6) Mpc(exp 3) over this epoch, allowing us to perform a robust search for bright (M(sub UV) less than -21) and faint (M(sub UV) = -18) galaxies. We select galaxies using a well-tested photometric redshift technique with careful screening of contaminants, finding a sample of 7446 galaxies at 3.5 less than z less than 8.5, with more than 1000 galaxies at z of approximately 6 - 8. We measure both a stepwise luminosity function for galaxies in our redshift samples, as well as a Schechter function, using a Markov Chain Monte Carlo analysis to measure robust uncertainties. At the faint end our UV luminosity functions agree with previous studies, yet we find a higher abundance of UV-bright galaxies at z of greater than or equal to 6. Our bestfit value of the characteristic magnitude M* is consistent with -21 at z of greater than or equal to 5, different than that inferred based on previous trends at lower redshift. At z = 8, a single power-law provides an equally good fit to the UV luminosity function, while at z = 6 and 7, an exponential cutoff at the bright-end is moderately preferred. We compare our luminosity functions to semi-analytical models, and find that the lack of evolution in M* is consistent with models where the impact of dust attenuation on the bright-end of the luminosity function decreases at higher redshift, though a decreasing impact of feedback may also be possible. We measure the evolution of the cosmic star-formation rate (SFR) density by integrating our observed luminosity functions to M(sub UV) = -17, correcting for dust attenuation, and find that

  5. Evolution of cosmic filaments and of their galaxy population from MHD cosmological simulations

    Science.gov (United States)

    Gheller, C.; Vazza, F.; Brüggen, M.; Alpaslan, M.; Holwerda, B. W.; Hopkins, A. M.; Liske, J.

    2016-10-01

    Despite containing about a half of the total matter in the Universe, at most wavelengths the filamentary structure of the cosmic web is difficult to observe. In this work, we use large unigrid cosmological simulations to investigate how the geometrical, thermodynamical and magnetic properties of cosmological filaments vary with mass and redshift (z ≤ 1). We find that the average temperature, length, volume and magnetic field of filaments scales well with their total mass. This reflects the role of self-gravity in shaping their properties and enables statistical predictions of their observational properties based on their mass. We also focus on the properties of the simulated population of galaxy-sized haloes within filaments, and compare their properties to the results obtained from the spectroscopic GAMA survey. Simulated and observed filaments with the same length are found to contain an equal number of galaxies, with very similar distribution of masses. The total number of galaxies within each filament and the total/average stellar mass in galaxies can now be used to predict also the large-scale properties of the gas in the host filaments across tens or hundreds of Mpc in scale. These results are the first steps towards the future use of galaxy catalogues in order to select the best targets for observations of the warm-hot intergalactic medium.

  6. Bulgeless galaxies in the COSMOS field: environment and star formation evolution at z < 1

    Science.gov (United States)

    Grossi, Marco; Fernandes, Cristina A. C.; Sobral, David; Afonso, José; Telles, Eduardo; Bizzocchi, Luca; Paulino-Afonso, Ana; Matute, Israel

    2018-03-01

    Combining the catalogue of galaxy morphologies in the COSMOS field and the sample of H α emitters at redshifts z = 0.4 and z = 0.84 of the HiZELS survey, we selected ˜ 220 star-forming bulgeless systems (Sérsic index n ≤ 1.5) at both epochs. We present their star formation properties and we investigate their contribution to the star formation rate function (SFRF) and global star formation rate density (SFRD) at z 3). At both redshifts, the SFRF is dominated by the contribution of bulgeless galaxies and we show that they account for more than 60 per cent of the cosmic SFRD at z types, but it is stronger for bulge-dominated systems. Star-forming bulgeless systems are mostly located in regions of low to intermediate galaxy densities (Σ ˜ 1-4 Mpc-2) typical of field-like and filament-like environments and their specific star formation rates (sSFRs) do not appear to vary strongly with local galaxy density. Only few bulgeless galaxies in our sample have high (sSFR > 10-9 yr-1) and these are mainly low-mass systems. Above M* ˜ 1010 M⊙ bulgeless are evolving at a `normal' rate (10-9 yr-1 < sSFR < 10-10 yr-1) and in the absence of an external trigger (i.e. mergers/strong interactions) they might not be able to develop a central classical bulge.

  7. Formation of S0 galaxies through mergers. Evolution in the Tully-Fisher relation since z ∼ 1

    Science.gov (United States)

    Tapia, Trinidad; Eliche-Moral, M. Carmen; Aceves, Héctor; Rodríguez-Pérez, Cristina; Borlaff, Alejandro; Querejeta, Miguel

    2017-08-01

    Context. Lenticular (S0) galaxies are known to derive from spiral galaxies. The fact that S0s nearly obey the Tully-Fisher relation (TFR) at z ∼ 0 (as spirals have done in the last 9 Gyr) is considered an argument against their major-merger origin because equal mergers of two disc galaxies produce remnants that are outliers of the TFR. Aims: We explore whether a scenario that combines an origin by mergers at z ∼ 1.8 - 1.5 with a subsequent passive evolution of the resulting S0 remnants since z ∼ 0.8-1 is compatible with observational data of S0s in the TFR both at z ∼ 0.8 and z ∼ 0. Methods: We studied a set of major and minor merger experiments from the GalMer database that generate massive S0 remnants that are dynamically relaxed and have realistic properties. We analysed the location of these remnants in the photometric and stellar TFRs assuming that they correspond to z ∼ 0.8 galaxies. We then estimated their evolution in these planes over the last 7 Gyr considering that they have evolved passively in isolation. The results were compared with data of real S0s and spirals at different redshifts. We also tested how the use of Vcirc or Vrot,max affects the results. Results: Just after 1-2 Gyr of coalescence, major mergers generate S0 remnants that are outliers of the local photometric and stellar TFRs (as already stated in previous studies), in good agreement with observations at z ∼ 0.8. After 4-7 Gyr of passive evolution in isolation, the S0 remnants move towards the local TFR, although the initial scatter among them persists. This scatter is sensitive to the indicator used for the rotation velocity: Vcirc values yield a lower scatter than when Vrot,max values are considered instead. In the planes involving Vrot,max, a clear segregation of the S0 remnants in terms of the spin-orbit coupling of the model is observed, in which the remnants of retrograde encounters overlap with local S0s hosting counter-rotating discs. The location of the S0 remnants

  8. Galaxy evolution. Quasar quartet embedded in giant nebula reveals rare massive structure in distant universe.

    Science.gov (United States)

    Hennawi, Joseph F; Prochaska, J Xavier; Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio

    2015-05-15

    All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-α emission at redshift z ≈ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ∼10(-7), implying a physical connection between Lyman-α nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (≃10(11) solar masses) of cool dense (volume density ≃ 1 cm(-3)) gas, which is in conflict with current cosmological simulations. Copyright © 2015, American Association for the Advancement of Science.

  9. The Role of Environment in the SFHs and Gaseous Evolution of Ultra-Faint Dwarf Galaxies across Cosmic Time

    Science.gov (United States)

    Jeon, Myoungwon

    2017-08-01

    Ultra faint dwarf (UFD) galaxies (Mv > -7; Mstar generation of stars. Star formation histories (SFHs) derived from deep HST/ACS imaging of several MW UFDs illustrate quenching of the era of reionization. However, new HST studies of the faintest dwarfs about M31 recently revealed more diverse SFHs, indicating that a wide range of evolutionary paths are possible for UFDs. Interpretation of these data is not possible without hydrodynamic cosmological simulations that account for not only the impact of reionization and stellar feedback, but also the host environment. Such simulations do not currently exist. We propose to create a large suite of cosmological, hydrodynamic simulations of UFD analogs that reside 100 kpc from a MW type host at z = 0. These novel simulations will allow us to quantify the role of host's tidal field on the SFHs and gaseous evolution of UFDs for the first time. Furthermore, our recent work indicates that UFDs can retain substantial gas reservoirs prior to accretion by a massive host. We will create mock absorption line observations of our simulated UFDs at intermediate redshifts to establish or refute the connection between local UFDs as descendants of metal-poor damped Lyman alpha systems. The proposed simulation suite will thus be of critical importance to a wide range of ongoing HST programs designed to understand the gaseous, chemical, and dynamical evolution of the dwarf galaxies across cosmic time.

  10. The inferred evolution of the cold gas properties of CANDELS galaxies at 0.5

    NARCIS (Netherlands)

    Popping, G.; Caputi, K. I.; Trager, S. C.; Somerville, R. S.; Dekel, A.; Kassin, S. A.; Kocevski, D. D.; Koekemoer, A. M.; Faber, S. M.; Ferguson, H. C.; Galametz, A.; Grogin, N. A.; Guo, Y.; Lu, Y.; van der Wel, A.; Weiner, B. J.

    2015-01-01

    We derive the total cold gas, atomic hydrogen, and molecular gas masses of approximately 24 000 galaxies covering four decades in stellar mass at redshifts 0.5

  11. Galaxy evolution, cosmology and dark energy with the Square Kilometer Array

    NARCIS (Netherlands)

    Rawlings, S; Abdalla, FB; Bridle, SL; Blake, CA; Baugh, CM; Greenhill, LJ; van der Hulst, JM

    2004-01-01

    The present-day Universe is seemingly dominated by dark energy and dark matter, but mapping the normal (baryonic) content remains vital for both astrophysics - understanding how galaxies form - and astro-particle physics inferring properties of the dark components. The Square Kilometer Array (SKA)

  12. The star formation and chemical evolution history of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    de Boer, T. J. L.; Tolstoy, E.; Hill, V.; Saha, A.; Olszewski, E. W.; Mateo, M.; Starkenburg, E.; Battaglia, G.; Walker, M. G.

    We present deep photometry in the B, V and I filters from CTIO/MOSAIC for about 270 000 stars in the Fornax dwarf spheroidal galaxy, out to a radius of rell ≈ 0.8 degrees. By combining the accurately calibrated photometry with the spectroscopic metallicity distributions of individual red giant

  13. The star formation and chemical evolution history of the sculptor dwarf spheroidal galaxy

    NARCIS (Netherlands)

    de Boer, T. J. L.; Tolstoy, E.; Hill, V.; Saha, A.; Olsen, K.; Starkenburg, E.; Lemasle, B.; Irwin, M. J.; Battaglia, G.

    We have combined deep photometry in the B, V and I bands from CTIO/MOSAIC of the Sculptor dwarf spheroidal galaxy, going down to the oldest main sequence turn-offs, with spectroscopic metallicity distributions of red giant branch stars. This allows us to obtain the most detailed and complete star

  14. The structural evolution of galaxies with both thin and thick discs

    Science.gov (United States)

    Aumer, Michael; Binney, James

    2017-09-01

    We perform controlled N-body simulations of disc galaxies growing within live dark matter (DM) haloes to present-day galaxies that contain both thin and thick discs. We consider two types of models: (a) thick-disc initial conditions to which stars on near-circular orbits are continuously added over ˜10 Gyr, and (b) models in which the birth velocity dispersion of stars decreases continuously over the same time-scale. We show that both schemes produce double-exponential vertical profiles similar to that of the Milky Way (MW). We indicate how the spatial age structure of galaxies can be used to discriminate between scenarios. We show that the presence of a thick disc significantly alters and delays bar formation and thus makes possible models with a realistic bar and a high baryon-to-DM mass ratio in the central regions, as required by microlensing constraints. We examine how the radial mass distribution in stars and DM is affected by disc growth and non-axisymmetries. We discuss how bar buckling shapes the vertical age distribution of thin- and thick-disc stars in the bar region. The extent to which the combination of observationally motivated inside-out growth histories and cosmologically motivated dark halo properties leads to the spontaneous formation of non-axisymmetries that steer the models towards present-day MW-like galaxies is noteworthy.

  15. The Hy-Redshift Universe: Galaxy Formation and Evolution at High Redshift

    Energy Technology Data Exchange (ETDEWEB)

    Bunker, A.J.; van Breugel, W.J.M.

    1999-11-03

    Hyron Spinrad's career has spanned several decades, and has stretched from our neighboring planets to the most remote galaxies in the Universe, pausing in between to ''enrich'' our knowledge of the compositions of stars.

  16. The chemical evolution of dwarf spheroidal galaxies : dissecting the inner regions and their stellar populations

    NARCIS (Netherlands)

    Marcolini, A.; D'Ercole, A.; Battaglia, G.; Gibson, B. K.

    2008-01-01

    Using three-dimensional hydrodynamical simulations of isolated dwarf spheroidal galaxies (dSphs), we undertake an analysis of the chemical properties of their inner regions, identifying the respective roles played by Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II). The effect of

  17. GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.

    Science.gov (United States)

    Trakhtenbrot, Benny; Urry, C Megan; Civano, Francesca; Rosario, David J; Elvis, Martin; Schawinski, Kevin; Suh, Hyewon; Bongiorno, Angela; Simmons, Brooke D

    2015-07-10

    Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow. Copyright © 2015, American Association for the Advancement of Science.

  18. RX J0848.6+4453: The evolution of galaxy sizes and stellar populations in A z = 1.27 cluster

    Energy Technology Data Exchange (ETDEWEB)

    Jørgensen, Inger; Chiboucas, Kristin; Schiavon, Ricardo P. [Gemini Observatory, 670 North A' ohoku Place, Hilo, HI 96720 (United States); Toft, Sune; Zirm, Andrew [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark); Bergmann, Marcel [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Grützbauch, Ruth, E-mail: ijorgensen@gemini.edu, E-mail: kchiboucas@gemini.edu, E-mail: R.P.Schiavon@ljmu.ac.uk, E-mail: sune@dark-cosmology.dk, E-mail: andrewzirm@gmail.com, E-mail: marcelbergmann@gmail.com, E-mail: ruthregenborgen@gmail.com [Center for Astronomy and Astrophysics, University of Lisbon, Lisbon (Portugal)

    2014-12-01

    RX J0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. We present an analysis of the stellar populations and star formation history for a sample of 24 members of the cluster. Our study is based on deep optical spectroscopy obtained with Gemini North combined with imaging data from Hubble Space Telescope. Focusing on the 13 bulge-dominated galaxies for which we can determine central velocity dispersions, we find that these show a smaller evolution with redshift of sizes and velocity dispersions than reported for field galaxies and galaxies in poorer clusters. Our data show that the galaxies in RX J0848.6+4453 populate the fundamental plane (FP) similar to that found for lower-redshift clusters. The zero-point offset for the FP is smaller than expected if the cluster's galaxies are to evolve passively through the location of the FP we established in our previous work for z = 0.8-0.9 cluster galaxies and then to the present-day FP. The FP zero point for RX J0848.6+4453 corresponds to an epoch of last star formation at z{sub form}=1.95{sub −0.15}{sup +0.22}. Further, we find that the spectra of the galaxies in RX J0848.6+4453 are dominated by young stellar populations at all galaxy masses and in many cases show emission indicating low-level ongoing star formation. The average age of the young stellar populations as estimated from the strength of the high-order Balmer line Hζ is consistent with a major star formation episode 1-2 Gyr prior, which in turn agrees with z {sub form} = 1.95. These galaxies dominated by young stellar populations are distributed throughout the cluster. We speculate that low-level star formation has not yet been fully quenched in the center of this cluster, possibly because the cluster is significantly poorer than other clusters previously studied at similar redshifts, which appear to have very little ongoing star formation in their centers. The mixture in RX J0848.6+4453 of passive galaxies with young

  19. The co-evolution of the obscured quasar PKS 1549-79 and its host galaxy : evidence for a high accretion rate and warm outflow

    NARCIS (Netherlands)

    Holt, J.; Tadhunter, C. N.; Morganti, R.; Bellamy, M.; González-Delgado, R. M.; Tzioumis, A.; Inskip, K. J.

    2006-01-01

    We use deep optical, infrared and radio observations to explore the symbiosis between nuclear activity and galaxy evolution in the southern compact radio source PKS 1549-79 (z = 0.1523). The optical imaging observations reveal the presence of tidal tail features which provide strong evidence that

  20. xCOLD GASS: The Complete IRAM 30 m Legacy Survey of Molecular Gas for Galaxy Evolution Studies

    Science.gov (United States)

    Saintonge, Amélie; Catinella, Barbara; Tacconi, Linda J.; Kauffmann, Guinevere; Genzel, Reinhard; Cortese, Luca; Davé, Romeel; Fletcher, Thomas J.; Graciá-Carpio, Javier; Kramer, Carsten; Heckman, Timothy M.; Janowiecki, Steven; Lutz, Katharina; Rosario, David; Schiminovich, David; Schuster, Karl; Wang, Jing; Wuyts, Stijn; Borthakur, Sanchayeeta; Lamperti, Isabella; Roberts-Borsani, Guido W.

    2017-12-01

    We introduce xCOLD GASS, a legacy survey providing a census of molecular gas in the local universe. Building on the original COLD GASS survey, we present here the full sample of 532 galaxies with CO (1–0) measurements from the IRAM 30 m telescope. The sample is mass-selected in the redshift interval 0.01 {10}9 {M}ȯ . The CO (1–0) flux measurements are complemented by observations of the CO (2–1) line with both the IRAM 30 m and APEX telescopes, H I observations from Arecibo, and photometry from SDSS, WISE, and GALEX. Combining the IRAM and APEX data, we find that the ratio of CO (2–1) to CO (1–0) luminosity for integrated measurements is {r}21=0.79+/- 0.03, with no systematic variations across the sample. The CO (1–0) luminosity function is constructed and best fit with a Schechter function with parameters {L}{CO}* =(7.77+/- 2.11)× {10}9 {{K}} {km} {{{s}}}-1 {{pc}}2, {φ }* =(9.84+/- 5.41)× {10}-4 {{Mpc}}-3, and α =-1.19+/- 0.05. With the sample now complete down to stellar masses of 109 {M}ȯ , we are able to extend our study of gas scaling relations and confirm that both molecular gas fractions ({f}{{{H}}2}) and depletion timescale ({t}{dep}({{{H}}}2)) vary with specific star formation rate (or offset from the star formation main sequence) much more strongly than they depend on stellar mass. Comparing the xCOLD GASS results with outputs from hydrodynamic and semianalytic models, we highlight the constraining power of cold gas scaling relations on models of galaxy formation.

  1. Using Ground Penetrating Radar to Constrain the Drainage Evolution in Southern Egypt and Implications for Future Deployment on Mars

    Science.gov (United States)

    Grant, J. A.; Maxwell, T. A.; Johnston, A. K.; Leuschen, C. J.; Schutz, A. E.; Williams, K. K.

    2004-05-01

    Ground penetrating radar (GPR) constrains the origin of relict and largely buried fluvial channels in the Bir Kiseiba region of southern Egypt. GPR results indicate that the trunk channel to a tributary system identified in Shuttle Imaging Radar (SIR) data is incised 10 to 12 meters into bedrock, was southwest-draining and laterally migrating toward the northwest, and accentuated relief along the nearby Kiseiba escarpment. Alluvium partially filling the main channel likely reflects effects of increasing aridity and bed load combined with less frequent, flashier precipitation. In contrast to defining channel margins, GPR data do not indicate subtle stratigraphic changes in bedding related to fluvial aggradation, but do highlight local reflections likely corresponding to relict alluvial bar forms. These GPR data complement the SIR and field data and permit a better understanding of the evolution of this enigmatic landscape. The Egyptian study area occurs in a region long considered to possess potential analogs for landforms on Mars. GPR results from Egypt and other analog terrain combined with consideration of factors influencing radar performance on Mars instill confidence that a rover-deployed GPR can achieve 10 to 20 m penetration and provide critical constraint on geologic setting and context for other rover instruments. To take advantage of this potential, a rover-deployable impulse GPR is under development for future Mars missions and possesses mass, volume, and power limits of 0.5 kg, 3400 cc, 3 W (peak), respectively. The GPR has no moving parts, includes a body conformal antenna capable of configuration at 150 MHz to more than 600 MHz, will collect 0.3 MB data per day (assuming a 50 meter traverse), and is being successfully tested in Mars analog environments. By analogy to the results from Egypt, a Mars GPR deployed in the vicinity of valley networks should be able to distinguish diagnostic signatures required for identifying the sources of water

  2. A Zoo of Galaxies

    Science.gov (United States)

    Masters, Karen L.

    2015-03-01

    We live in a universe filled with galaxies with an amazing variety of sizes and shapes. One of the biggest challenges for astronomers working in this field is to understand how all these types relate to each other in the background of an expanding universe. Modern astronomical surveys (like the Sloan Digital Sky Survey) have revolutionised this field of astronomy, by providing vast numbers of galaxies to study. The sheer size of the these databases made traditional visual classification of the types galaxies impossible and in 2007 inspired the Galaxy Zoo project (www.galaxyzoo.org); starting the largest ever scientific collaboration by asking members of the public to help classify galaxies by type and shape. Galaxy Zoo has since shown itself, in a series of now more than 30 scientific papers, to be a fantastic database for the study of galaxy evolution. In this Invited Discourse I spoke a little about the historical background of our understanding of what galaxies are, of galaxy classification, about our modern view of galaxies in the era of large surveys. I finish with showcasing some of the contributions galaxy classifications from the Galaxy Zoo project are making to our understanding of galaxy evolution.

  3. The structural evolution of Milky-Way-like star-forming galaxies since z ∼ 1.3

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Shannon G.; Fumagalli, Mattia; Franx, Marijn; Labbé, Ivo; Muzzin, Adam [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 AA Leiden (Netherlands); Van Dokkum, Pieter G.; Leja, Joel; Skelton, Rosalind E.; Momcheva, Ivelina; Nelson, Erica June [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Van der Wel, Arjen; Rix, Hans-Walter [Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Brammer, Gabriel [European Southern Observatory, Alonson de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Whitaker, Katherine E. [Astrophysics Science Division, Goddard Space Center, Greenbelt, MD 20771 (United States); Lundgren, Britt; Wake, David A. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States); Quadri, Ryan F., E-mail: patel@strw.leidenuniv.nl [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)

    2013-12-01

    We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ∼ 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HST survey, which utilizes spectroscopy from the HST/WFC3 G141 near-IR grism and enables precise redshift measurements for our sample of SFGs. Structural properties are obtained from Sérsic profile fits to CANDELS WFC3 imaging. The progenitors of z = 0 SFGs with stellar mass M = 10{sup 10.5} M {sub ☉} are typically half as massive at z ∼ 1. This late-time stellar mass growth is consistent with recent studies that employ abundance matching techniques. The descendant SFGs at z ∼ 0 have grown in half-light radius by a factor of ∼1.4 since z ∼ 1. The half-light radius grows with stellar mass as r{sub e} ∝M {sup 0.29}. While most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late-type galaxies. Some portion of this growth in the central regions is due to star formation as recent observations of Hα maps for SFGs at z ∼ 1 are found to be extended but centrally peaked. Connecting our lookback study with galactic archeology, we find the stellar mass surface density at R = 8 kpc to have increased by a factor of ∼2 since z ∼ 1, in good agreement with measurements derived for the solar neighborhood of the Milky Way.

  4. The Structural Evolution of Milky-Way-Like Star-Forming Galaxies zeta is approximately 1.3

    Science.gov (United States)

    Patel, Shannon G.; Fumagalli, Mattia; Franx, Marun; VanDokkum, Pieter G.; VanDerWel, Arjen; Leja, Joel; Labbe, Ivo; Brammr, Gabriel; Whitaker, Katherine E.; Skelton, Rosalind E.; hide

    2013-01-01

    We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to zeta is approx. 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HT survey, which utilizes spectroscopy from the HST-WFC3 G141 near-IR grism and enables precise redshift measurements for our sample of SFGs. Structural properties are obtained from Sersic profile fits to CANDELS WFC3 imaging. The progenitors of zeta = 0 SFGs with stellar mass M = 10(exp 10.5) solar mass are typically half as massive at zeta is approx. 1. This late-time stellar mass grow is consistent with recent studies that employ abundance matching techniques. The descendant SFGs at zeta is approx. 0 have grown in half-light radius by a factor of approx. 1.4 zeta is approx. 1. The half-light radius grows with stellar mass as r(sub e) alpha stellar mass(exp 0.29). While most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late-type galaxies. Some portion of this growth in the central regions is due to star formation as recent observations of H(a) maps for SFGs at zeta approx. are found to be extended but centrally peaked. Connecting our lookback study with galactic archeology, we find the stellar mass surface density at R - 8 kkpc to have increased by a factor of approx. 2 since zeta is approx. 1, in good agreement with measurements derived for the solar neighborhood of the Milky Way.

  5. MC 2: Constraining the Dark Matter Distribution of the Violent Merging Galaxy Cluster CIZA J2242.8+5301 by Piercing through the Milky Way

    Science.gov (United States)

    Jee, M. James; Stroe, Andra; Dawson, William; Wittman, David; Hoekstra, Henk; Brüggen, Marcus; Röttgering, Huub; Sobral, David; van Weeren, Reinout J.

    2015-03-01

    The galaxy cluster CIZA J2242.8+5301 at z = 0.19 is a merging system with a prominent (~2 Mpc long) radio relic, which together with the morphology of the X-ray emission provides strong evidence for a violent collision along the north-south axis. We present our constraints on the dark matter distribution of this unusual system using Subaru and Canada-France-Hawaii Telescope imaging data. Measuring a high signal-to-noise ratio lensing signal from this cluster is potentially a challenging task because of its proximity to the Milky Way plane (|b| ~ 5°). We overcome this challenge with careful observation planning and systematics control, which enables us to successfully map the dark matter distribution of the cluster with high fidelity. The resulting mass map shows that the mass distribution of CIZA J2242.8+5301 is highly elongated along the north-south merger axis inferred from the orientation of the radio relics. Based on our mass reconstruction, we identify two sub-clusters, which coincide with the cluster galaxy distributions. We determine their masses using Markov Chain Monte Carlo analysis by simultaneously fitting two Navarro-Frenk-White halos without fixing their centroids. The resulting masses of the northern and southern systems are M200=11.0-3.2+3.7× 1014 M⊙ and 9.8-2.5+3.8× 1014 M⊙ , respectively, indicating that we are witnessing a post-collision of two giant systems of nearly equal mass. When the mass and galaxy centroids are compared in detail, we detect ~1' (~190 kpc) offsets in both northern and southern sub-clusters. After investigating the statistical significance of the offsets by bootstrapping both mass and galaxy centroids, we find that the galaxy luminosity-mass offset for the northern clump is statistically significant at the >~ 2σ level whereas the detection is only marginal for the southern sub-cluster in part because of a relatively large mass centroid error. We conclude that it is yet premature to uniquely attribute the galaxy

  6. The role of interactions in galaxy evolution: A new perspective from the CALIFA and MaNGA Integral Field Spectroscopic surveys.

    Science.gov (United States)

    Barrera-Ballesteros, J. K.; Sanchez, S. F.; Califa Collaboration

    2016-06-01

    Interactions and mergers have been playing a paramount role to understand how galaxies evolve. In recent years integral field spectroscopic (IFS) observations have become routinely allowing researchers to conduct large IFS surveys. In this context, these surveys are providing a new observational scenario to probe the properties of galaxies at different stages of the interaction —from close pairs to post-merger galaxies. Even more, these surveys also include homogeneous observations of non-interacting galaxies which in turns allows to distinguish the processes induce by secular evolution from those driven by interactions. In this talk, We review the studies of interacting studies from the CALIFA survey. They consider from the thorough analysis of a single interactive systems (e.g., the Mice, Wild et al. 2014) to the the statistical study of physical properties of a large sample of interacting/merging galaxies such as their internal structure via their stellar and gas line-of-sight kinematic maps (Barrera-Ballesteros et al. 2015a) or the spatial distribution of the star-forming gas in these galaxies (Barrera-Ballesteros et al. 2015b). Then we present some of the on-going studies within the MaNGA survey. Due to its statistical power (sample size ~10000 objects), this survey will allow us to probe the properties of galaxies in a wide range of the interaction-parameter space. This in turn provides a unique view on the key parameters that affect the internal structure and properties of galaxies during the interaction and subsequent merger.

  7. The Role of Quenching Time in the Evolution of the Mass-size Relation of Passive Galaxies from the Wisp Survey

    Science.gov (United States)

    Zanella, A.; Scarlata, C.; Corsini, E. M.; Bedregal, A. G.; Dalla Bontà, E.; Atek, H.; Bunker, A. J.; . Colbert, J.; Dai, Y. S.; Henry, A.; Malkan, M.; Martin, C.; Rafelski, M.; Rutkowski, M. J.; Siana, B.; Teplitz, H.

    2016-06-01

    We analyze how passive galaxies at z ˜ 1.5 populate the mass-size plane as a function of their stellar age, to understand if the observed size growth with time can be explained with the appearance of larger quenched galaxies at lower redshift. We use a sample of 32 passive galaxies extracted from the Wide Field Camera 3 Infrared Spectroscopic Parallel (WISP) survey with spectroscopic redshift 1.3 ≲ z ≲ 2.05, specific star formation rates lower than 0.01 Gyr-1, and stellar masses above 4.5 × 1010 M ⊙. All galaxies have spectrally determined stellar ages from fitting of their rest-frame optical spectra and photometry with stellar population models. When dividing our sample into young (age ≤2.1 Gyr) and old (age >2.1 Gyr) galaxies we do not find a significant trend in the distributions of the difference between the observed radius and that predicted by the mass-size relation. This result indicates that the relation between the galaxy age and its distance from the mass-size relation, if it exists, is rather shallow, with a slope α ≳ -0.6. At face value, this finding suggests that multiple dry and/or wet minor mergers, rather than the appearance of newly quenched galaxies, are mainly responsible for the observed time evolution of the mass-size relation in passive galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  8. The Hierarchical Build-Up of Massive Galaxies And the Intracluster Light Since z=1

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Charlie; /Princeton U.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC; Kravtsov, Andrey V.; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI

    2007-03-19

    We use a set of simulation-based models for the dissipationless evolution of galaxies since z = 1 to constrain the fate of accreted satellites embedded in dark matter subhalos. These models assign stellar mass to dark matter halos at z = 1 by relating the observed galaxy stellar mass function (GSMF) to the halo+subhalo mass function monotonically. The evolution of the stellar mass content is then followed using halo merger trees extracted from N-body simulations. Our models are differentiated only in the fate assigned to satellite galaxies once subhalos, within which satellites are embedded, disrupt. These models are confronted with the observed evolution in the massive end of the GSMF, the z {approx} 0 brightest cluster galaxy (BCG)-cluster mass relation, and the combined BCG and intracluster light (ICL) luminosity distribution--all observables expected to evolve approximately dissipationlessly since z = 1. The combined observational constraints favor a model in which the vast majority ({approx}> 80%) of satellite stars from disrupted subhalos go into the ICL (operationally defined here as light below a surface brightness cut of {mu}{sub i} {approx} 23mag arcsec{sup -2}). Conversely, models that leave behind a significant population of satellite galaxies once the subhalo has disrupted are strongly disfavored, as are models that put a significant fraction of satellite stars into the BCG. Our results show that observations of the ICL provide useful and unique constraints on models of galaxy merging and the dissipationless evolution of galaxies in groups and clusters.

  9. The post-orogenic evolution of the Northeast Greenland Caledonides constrained from apatite fission track analysis and inverse geodynamic modelling

    DEFF Research Database (Denmark)

    Pedersen, Vivi Kathrine; Nielsen, S.B.; Gallagher, Kerry

    2012-01-01

    or deposition, and thermal histories are found by solving the one-dimensional transient conduction–advection heat equation. These thermal histories are used with the observed fission track data to constrain acceptable strain rate histories and exhumation paths. The results suggest that rifting has been focused...

  10. Near-IR Spectroscopy of Lyman Break Galaxies in Two QSO Fields

    Science.gov (United States)

    Moth, Pimol; Elston, Richard J.

    2001-02-01

    Recently there have been numerous detections of z>=3 galaxies using the Lyman break technique [8] allowing for direct observations of galaxies in a young state. We propose to conduct a comprehensive study of the properties of these Lyman break galaxies (LBGs) using near-IR spectroscopy to study the rest-frame optical emission lines H(beta), [OII] (lambda) 3727, and [OIII] (lambda)$(lambda) 4959, 5007. Observations of these emission lines will allow us to determine the source of excitations (AGN vs. star formation), star formation rates, chemical abundances, and nuclear velocity dispersions of LBGs in the fields of Q1244+1129 and Q1451+1223. By supplementing our near-IR observations with available observations of QSO absorption line spectra, we can constrain the total halo mass of each absorbing galaxy and consequently constrain the bias of galaxy formation. Ultimately, we will combine the information obtained from these spectra with existing HST NICMOS and WFPC-2 observations and galaxy formation models to determine the nature of LBGs. The 4-m coupled with the multi-slit capability of FLAMINGOS make it now efficient to carry out a comprehensive study of these LBGs. Study of these galaxies, when the universe was 10% of its current age, is crucial in our efforts to better understand galaxy formation and evolution.

  11. Emission-line Galaxies from the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) Grism Survey. II. The Complete Sample

    Science.gov (United States)

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Malhotra, Sangeeta; Rhoads, James E.; Grogin, Norman A.; Dahlen, Tomas; Noeske, Kai G.; Meurer, Gerhardt R.; Walsh, Jeremy R.; Hathi, Nimish P.; Cohen, Seth H.; Bellini, Andrea; Holwerda, Benne W.; Straughn, Amber N.; Mechtley, Matthew; Windhorst, Rogier A.

    2013-07-01

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitess grism spectroscopic data obtained with the Advanced Camera for Surveys on board Hubble Space Telescope. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random survey of galaxies, as well as the availability of a wide variety of ancillary observations complemented by the spectroscopic results. Using the PEARS data, we are able to identify star-forming galaxies (SFGs) within the redshift volume 0 = 109 M ⊙ decreases by an order of magnitude at z <= 0.5 relative to the number at 0.5 < z < 0.9, supporting the argument of galaxy downsizing.

  12. Galaxy kinematics in the XMMU J2235-2557 cluster field at z 1.4

    Science.gov (United States)

    Pérez-Martínez, J. M.; Ziegler, B.; Verdugo, M.; Böhm, A.; Tanaka, M.

    2017-09-01

    Aims: The relationship between baryonic and dark components in galaxies varies with the environment and cosmic time. Galaxy scaling relations describe strong trends between important physical properties. A very important quantitative tool in case of spiral galaxies is the Tully-Fisher relation (TFR), which combines the luminosity of the stellar population with the characteristic rotational velocity (Vmax) taken as proxy for the total mass. In order to constrain galaxy evolution in clusters, we need measurements of the kinematic status of cluster galaxies at the starting point of the hierarchical assembly of clusters and the epoch when cosmic star formation peaks. Methods: We took spatially resolved slit FORS2 spectra of 19 cluster galaxies at z 1.4, and 8 additional field galaxies at 1 photometric campaigns as [OII] and Hα emitters. Our spectroscopy was complemented with HST/ACS imaging in the F775W and F850LP filters, which is mandatory to derive the galaxy structural parameters accurately. We analyzed the ionized gas kinematics by extracting rotation curves from the two-dimensional spectra. Taking into account all geometrical, observational, and instrumental effects, we used these rotation curves to derive the intrinsic maximum rotation velocity. Results: Vmax was robustly determined for six cluster galaxies and three field galaxies. Galaxies with sky contamination or insufficient spatial rotation curve extent were not included in our analysis. We compared our sample to the local B-band TFR and the local velocity-size relation (VSR), finding that cluster galaxies are on average 1.6 mag brighter and a factor 2-3 smaller. We tentatively divided our cluster galaxies by total mass (I.e., Vmax) to investigate a possible mass dependency in the environmental evolution of galaxies. The averaged deviation from the local TFR is ⟨ ΔMB ⟩ = -0.7 for the high-mass subsample (Vmax > 200 km s-1). This mild evolution may be driven by younger stellar populations (SP) of

  13. Star Clusters in Tidal Debris: A UV Survey of Stellar Populations, Galaxy Interactions, and Evolution

    Science.gov (United States)

    Rodruck, Michael

    2017-08-01

    Tidal tails afford us a unique window into the processes shaping star formation, offering an unobstructed view of the star formation environment in these outskirts. The latest galactic merger simulations are finding an unexpected increase of star formation in extended tidal debris, with 20 - 50% of the systems star formation rate occurring in these regions. We see this observationally in massive clusters forming in the Tadpole galaxy, occupying 30% of the system's star formation rate. At the same time, clusters suffer high rates of disruption, dispersing their material into the diffuse light of the tail and mixing with old stars drawn from the parent galaxies. We intend to break our tidal tails into their composite populations using HST and ground-based Gemini imaging. Our existing WFPC2 VI-band and HI data indicate clusters prefer to live in regions of high HI kinetic energy and low shear. However, analysis is limited to population studies, as the lack of UB-band data prevents us from age or mass estimates, permitting only a shallow understanding of the relationship between local HI properties and star clusters. Additionally, while the high resolution of HST is necessary for identifying and studying star clusters, it is unsuitable for the sensitive imaging needed to study the faint, diffuse tails. Our proposed 11 orbits of WFC3/ACS UB-band imaging will allow for precise age and mass measurements of our star clusters, while ground-based imaging searches the diffuse light for the cluster destruction history. In this manner, we will determine the present and past history of star formation in tidal tails, and the HI densities and kinematics required for cluster formation.

  14. A Catalog of Edge-on Disk Galaxies: From Galaxies with a Bulge to Superthin Galaxies

    OpenAIRE

    Kautsch, S. J.; Grebel, E. K.; Barazza, F. D.; Gallagher, J. S.

    2005-01-01

    The formation and evolution of disk-dominated galaxies is difficult to explain, yet these objects exist. We therefore embarked on a study aimed at a better understanding of these enigmatic objects. We used data from the SDSS DR1 in order to identify edge-on galaxies with disks in a uniform, reproducible, automated fashion. We identified 3169 edge-on disk galaxies, which we subdivided into disk galaxies with bulge, intermediate types, and simple disk galaxies without any obvious bulge componen...

  15. The Evolution of Normal Galaxy X-Ray Emission Through Cosmic History: Constraints from the 6 MS Chandra Deep Field-South

    Science.gov (United States)

    Lehmer, B. D.; Basu-Zych, A. R.; Mineo, S.; Brandt, W. N.; Eurfrasio, R. T.; Fragos, T.; Hornschemeier, A. E.; Lou, B.; Xue, Y. Q.; Bauer, F. E.; hide

    2016-01-01

    We present measurements of the evolution of normal-galaxy X-ray emission from z (is) approx. 0-7 using local galaxies and galaxy samples in the approx. 6 Ms Chandra Deep Field-South (CDF-S) survey. The majority of the CDF-S galaxies are observed at rest-frame energies above 2 keV, where the emission is expected to be dominated by X-ray binary (XRB) populations; however, hot gas is expected to provide small contributions to the observed-frame (is) less than 1 keV emission at z (is) less than 1. We show that a single scaling relation between X-ray luminosity (L(sub x)) and star-formation rate (SFR) literature, is insufficient for characterizing the average X-ray emission at all redshifts. We establish that scaling relations involving not only SFR, but also stellar mass and redshift, provide significantly improved characterizations of the average X-ray emission from normal galaxy populations at z (is) approx. 0-7. We further provide the first empirical constraints on the redshift evolution of X-ray emission from both low-mass XRB (LMXB) and high-mass XRB (HMXB) populations and their scalings with stellar mass and SFR, respectively. We find L2 -10 keV(LMXB)/stellar mass alpha (1+z)(sub 2-3) and L2 -10 keV(HMXB)/SFR alpha (1+z), and show that these relations are consistent with XRB population-synthesis model predictions, which attribute the increase in LMXB and HMXB scaling relations with redshift as being due to declining host galaxy stellar ages and metallicities, respectively. We discuss how emission from XRBs could provide an important source of heating to the intergalactic medium in the early universe, exceeding that of active galactic nuclei.

  16. Testing for X-Ray-SZ Differences and Redshift Evolution in the X-Ray Morphology of Galaxy Clusters

    Science.gov (United States)

    Nurgaliev, D.; McDonald, M.; Benson, B. A.; Bleem, L.; Bocquet, S.; Forman, W. R.; Garmire, G. P.; Gupta, N.; Hlavacek-Larrondo, J.; Mohr, J. J.; Nagai, D.; Rapetti, D.; Stark, A. A.; Stubbs, C. W.; Vikhlinin, A.

    2017-05-01

    We present a quantitative study of the X-ray morphology of galaxy clusters, as a function of their detection method and redshift. We analyze two separate samples of galaxy clusters: a sample of 36 clusters at 0.35Pole Telescope. Clusters from both samples have similar-quality Chandra observations, which allow us to quantify their X-ray morphologies via two distinct methods: centroid shifts (w) and photon asymmetry ({A}{phot}). The latter technique provides nearly unbiased morphology estimates for clusters spanning a broad range of redshift and data quality. We further compare the X-ray morphologies of X-ray- and SZ-selected clusters with those of simulated clusters. We do not find a statistically significant difference in the measured X-ray morphology of X-ray and SZ-selected clusters over the redshift range probed by these samples, suggesting that the two are probing similar populations of clusters. We find that the X-ray morphologies of simulated clusters are statistically indistinguishable from those of X-ray- or SZ-selected clusters, implying that the most important physics for dictating the large-scale gas morphology (outside of the core) is well-approximated in these simulations. Finally, we find no statistically significant redshift evolution in the X-ray morphology (both for observed and simulated clusters), over the range of z˜ 0.3 to z˜ 1, seemingly in contradiction with the redshift-dependent halo merger rate predicted by simulations.

  17. Galaxy And Mass Assembly: the evolution of the cosmic spectral energy distribution from z = 1 to z = 0

    Science.gov (United States)

    Andrews, S. K.; Driver, S. P.; Davies, L. J. M.; Kafle, P. R.; Robotham, A. S. G.; Vinsen, K.; Wright, A. H.; Bland-Hawthorn, J.; Bourne, N.; Bremer, M.; da Cunha, E.; Drinkwater, M.; Holwerda, B.; Hopkins, A. M.; Kelvin, L. S.; Loveday, J.; Phillipps, S.; Wilkins, S.

    2017-09-01

    We present the evolution of the cosmic spectral energy distribution (CSED) from z = 1 to 0. Our CSEDs originate from stacking individual spectral energy distribution (SED) fits based on panchromatic photometry from the Galaxy And Mass Assembly (GAMA) and COSMOS data sets in 10 redshift intervals with completeness corrections applied. Below z = 0.45, we have credible SED fits from 100 nm to 1 mm. Due to the relatively low sensitivity of the far-infrared data, our far-infrared CSEDs contain a mix of predicted and measured fluxes above z = 0.45. Our results include appropriate errors to highlight the impact of these corrections. We show that the bolometric energy output of the Universe has declined by a factor of roughly 4 - from 5.1 ± 1.0 at z ˜ 1 to 1.3 ± 0.3 × 1035 h70 W Mpc-3 at the current epoch. We show that this decrease is robust to cosmic sample variance, the SED modelling and other various types of error. Our CSEDs are also consistent with an increase in the mean age of stellar populations. We also show that dust attenuation has decreased over the same period, with the photon escape fraction at 150 nm increasing from 16 ± 3 at z ˜ 1 to 24 ± 5 per cent at the current epoch, equivalent to a decrease in AFUV of 0.4 mag. Our CSEDs account for 68 ± 12 and 61 ± 13 per cent of the cosmic optical and infrared backgrounds, respectively, as defined from integrated galaxy counts and are consistent with previous estimates of the cosmic infrared background with redshift.

  18. Quantifying the average properties of hot gaseous coronae around spiral galaxies

    Science.gov (United States)

    Bogdan, Akos

    2017-09-01

    Hot gaseous coronae within the dark matter halos of massive spiral galaxies is a fundamental prediction of galaxy formation models. Although the first X-ray coronae around massive spirals have been detected recently, their average characteristics remain poorly understood due to their faint nature. This program aims to overturn this picture and measure the average properties of the hot coronae beyond the stellar body of spiral galaxies. We propose to stack the X-ray data of a large number of massive spirals observed within wide-area Chandra survey fields. The observed properties of the coronae will be confronted with state-of-the-art galaxy formation models, which will allow us to constrain crucial physical processes that influence galaxy evolution.

  19. EMISSION-LINE GALAXIES FROM THE HUBBLE SPACE TELESCOPE PROBING EVOLUTION AND REIONIZATION SPECTROSCOPICALLY (PEARS) GRISM SURVEY. II. THE COMPLETE SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Grogin, Norman A.; Dahlen, Tomas; Noeske, Kai G.; Bellini, Andrea [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21210 (United States); Malhotra, Sangeeta; Rhoads, James E.; Cohen, Seth H.; Mechtley, Matthew; Windhorst, Rogier A. [School of Earth And Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Meurer, Gerhardt R. [International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Walsh, Jeremy R. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Hathi, Nimish P. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Holwerda, Benne W. [ESA-ESTEC, Keplerlaan 1, 2200 AG, Noordwijk (Netherlands); Straughn, Amber N. [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)

    2013-07-20

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitess grism spectroscopic data obtained with the Advanced Camera for Surveys on board Hubble Space Telescope. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random survey of galaxies, as well as the availability of a wide variety of ancillary observations complemented by the spectroscopic results. Using the PEARS data, we are able to identify star-forming galaxies (SFGs) within the redshift volume 0 < z < 1.5. Star-forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allows us to detect the presence of multiple emission-line regions (ELRs) within a single galaxy. We identified a total of 1162 H{alpha}, [O III], and/or [O II] emission lines in the PEARS sample of 906 galaxies to a limiting flux of {approx}10{sup -18} erg s{sup -1} cm{sup -2}. The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis, we find three key results: (1) the computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; (2) the star-forming systems show evidence of complex morphologies with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass. (3) Also, the number density of SFGs with M{sub *} {>=} 10{sup 9} M{sub Sun} decreases by an order of magnitude at z {<=} 0.5 relative to the number at 0.5 < z < 0.9, supporting the argument of galaxy downsizing.

  20. Evolution of thermally pulsing asymptotic giant branch stars. IV. Constraining mass loss and lifetimes of low mass, low metallicity AGB stars

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfield, Philip; Dalcanton, Julianne J.; Weisz, Daniel; Williams, Benjamin F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Marigo, Paola [Department of Physics and Astronomy G. Galilei, University of Padova, Vicolo dell' Osservatorio 3, I-35122 Padova (Italy); Girardi, Léo; Gullieuszik, Marco [Osservatorio Astronomico di Padova—INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Bressan, Alessandro [Astrophysics Sector, SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Dolphin, Andrew [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Aringer, Bernhard [Department of Astrophysics, University of Vienna, Turkenschanzstraße 17, A-1180 Wien (Austria)

    2014-07-20

    The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] ≲ –0.86) galaxies taken from the ACS Nearby Galaxy Survey Treasury sample, using Hubble Space Telescope (HST) photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and red giant branch (RGB) stars, N{sub TP-AGB}/N{sub RGB}, to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust mass loss is important, since models that neglect pre-dust mass loss fail to explain the observed N{sub TP-AGB}/N{sub RGB} ratio or the luminosity functions. In contrast, models with more efficient pre-dust mass loss produce results consistent with observations. We find that for [Fe/H] ≲ –0.86, lower mass TP-AGB stars (M ≲ 1 M{sub ☉}) must have lifetimes of ∼0.5 Myr and higher masses (M ≲ 3 M{sub ☉}) must have lifetimes ≲ 1.2 Myr. In addition, assuming our best-fitting mass-loss prescription, we show that the third dredge-up has no significant effect on TP-AGB lifetimes in this mass and metallicity range.

  1. Snapshots in X-ray binary evolution: Using Hα Emitters and post-starburst galaxies to study the age-dependence of XRB populations

    Science.gov (United States)

    Basu-Zych, Antara; Hornschemeier, Ann; Fragkos, Anastasios; Lehmer, Bret; Zezas, Andreas; Yukita, Mihoko; Tzanavaris, Panayiotis

    2018-01-01

    The X-ray emission in galaxies, due to X-ray binaries (XRBs), appears to depend on global galaxy properties such as stellar mass (M*), star formation rate (SFR), metallicity, and stellar age. This poster will present unique galaxy populations with well-defined stellar ages to test current relations and models. Specifically, Hα emitters (HAEs), which are nearby analogs of galaxies in the early universe, trace how XRBs form and evolve in young, metal-poor environments. We find that HAEs have lower X-ray luminosities per SFR and metallicity compared to other normal galaxies. At such young ages ( 500 Å), probe the XRB population related to stellar ages of 0.1-1 Gyr. At these ages, the donor star is expected to be an A-star whose mass is ~2 M⊙ and similar to that of the compact object, which may potentially lead to high mass transfer rates and high X-ray luminosities. Together, these samples offer important constraints for the evolution of XRBs with stellar age.

  2. Imprints of reionization in galaxy clustering

    Science.gov (United States)

    Schmidt, Fabian; Beutler, Florian

    2017-10-01

    Reionization, the only phase transition in the Universe since recombination, is a key event in the cosmic history of baryonic matter. We derive, in the context of the large-scale bias expansion, the imprints of the epoch of reionization in the large-scale distribution of galaxies and identify two contributions of particular importance. First, the Compton scattering of cosmic microwave background photons off the free electrons lead to a drag force on the baryon fluid. This drag induces a relative velocity between baryons and cold dark matter, which is of the same order of magnitude as the primordially induced relative velocity, and enters in the evolution of the relative velocity as calculated by Boltzmann codes. This leads to a unique contribution to galaxy bias involving the matter velocity squared. The second important effect is a modulation of the galaxy density by the ionizing radiation field through radiative-transfer effects, which is captured in the bias expansion by so-called higher-derivative terms. We constrain both of these imprints using the power spectrum of the BOSS DR12 galaxy sample. While they do not lead to a shift in the baryon acoustic oscillation scale, including these terms is important for unbiased cosmology constraints from the shape of the galaxy power spectrum.

  3. Modelling the formation and evolution of star cluster populations in galaxy simulations

    NARCIS (Netherlands)

    Kruijssen, J.M.D.|info:eu-repo/dai/nl/325799911; Pelupessy, F.I.; Lamers, H.J.G.L.M.|info:eu-repo/dai/nl/072834870; Portegies Zwart, S.F.; Icke, V.

    2011-01-01

    The formation and evolution of star cluster populations are related to the galactic environment. Cluster formation is governed by processes acting on galactic scales, and star cluster disruption is driven by the tidal field. In this paper, we present a self-consistent model for the formation and

  4. A new fitting-function to describe the time evolution of a galaxy's gravitational potential

    NARCIS (Netherlands)

    Buist, Hans J. T.; Helmi, Amina

    We present a new simple functional form to model the evolution of a spherical mass distribution in a cosmological context. Two parameters control the growth of the system and this is modelled using a redshift-dependent exponential for the scale mass and scale radius. In this new model, systems form

  5. The HERschel Inventory of the Agents of Galaxy Evolution in the Magellanic Clouds, a HERschel Open Time Key Program

    Science.gov (United States)

    Meixner, Margaret; Panuzzo, P.; Roman-Duval, J.; Engelbracht, C.; Babler, B.; Seale, J.; Hony, S.; Montiel, E.; Sauvage, M.; Gordon, K.; hide

    2013-01-01

    We present an overview or the HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) in the Magellanic Clouds project, which is a Herschel Space Observatory open time key program. We mapped the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) at 100, 160, 250, 350, and 500 micron with the Spectral and Photometric Imaging Receiver (SPIRE) and Photodetector Array Camera and Spectrometer (PACS) instruments on board Herschel using the SPIRE/PACS parallel mode. The overriding science goal of HERITAGE is to study the life cycle of matter as traced by dust in the LMC and SMC. The far-infrared and submillimeter emission is an effective tracer of the interstellar medium (ISM) dust, the most deeply embedded young stellar objects (YSOs), and the dust ejected by the most massive stars. We describe in detail the data processing, particularly for the PACS data, which required some custom steps because of the large angular extent of a single observational unit and overall the large amount of data to be processed as an ensemble. We report total global fluxes for LMC and SMC and demonstrate their agreement with measurements by prior missions. The HERITAGE maps of the LMC and SMC are dominated by the ISM dust emission and bear most resemblance to the tracers of ISM gas rather than the stellar content of the galaxies. We describe the point source extraction processing and the critetia used to establish a catalog for each waveband for the HERITAGE program. The 250 micron band is the most sensitive and the source catalogs for this band have approx. 25,000 objects for the LMC and approx. 5500 objects for the SMC. These data enable studies of ISM dust properties, submillimeter excess dust emission, dust-to-gas ratio, Class 0 YSO candidates, dusty massive evolved stars, supemova remnants (including SN1987A), H II regions, and dust evolution in the LMC and SMC. All images and catalogs are delivered to the Herschel Science Center as part of the conummity support

  6. THE HERSCHEL INVENTORY OF THE AGENTS OF GALAXY EVOLUTION IN THE MAGELLANIC CLOUDS, A HERSCHEL OPEN TIME KEY PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Meixner, M.; Roman-Duval, J.; Seale, J.; Gordon, K.; Beck, T.; Boyer, M. L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Panuzzo, P.; Hony, S.; Sauvage, M.; Okumura, K.; Chanial, P. [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Engelbracht, C.; Montiel, E.; Misselt, K. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Babler, B. [Department of Astronomy, 475 North Charter Street, University of Wisconsin, Madison, WI 53706 (United States); Bernard, J.-P. [CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Bolatto, A. [Department of Astronomy, Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Bot, C. [Universite de Strasbourg, Observatoire Astronomique de Strasbourg, 11, Rue de l' Universite, F-67000 Strasbourg (France); Carlson, L. R. [Sterrewacht Leiden, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Clayton, G. C., E-mail: meixner@stsci.edu [Department of Physics and Astronomy, Louisiana State University, 233-A Nicholson Hall, Tower Drive, Baton Rouge, LA 70803-4001 (United States); and others

    2013-09-15

    We present an overview of the HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) in the Magellanic Clouds project, which is a Herschel Space Observatory open time key program. We mapped the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) at 100, 160, 250, 350, and 500 {mu}m with the Spectral and Photometric Imaging Receiver (SPIRE) and Photodetector Array Camera and Spectrometer (PACS) instruments on board Herschel using the SPIRE/PACS parallel mode. The overriding science goal of HERITAGE is to study the life cycle of matter as traced by dust in the LMC and SMC. The far-infrared and submillimeter emission is an effective tracer of the interstellar medium (ISM) dust, the most deeply embedded young stellar objects (YSOs), and the dust ejected by the most massive stars. We describe in detail the data processing, particularly for the PACS data, which required some custom steps because of the large angular extent of a single observational unit and overall the large amount of data to be processed as an ensemble. We report total global fluxes for the LMC and SMC and demonstrate their agreement with measurements by prior missions. The HERITAGE maps of the LMC and SMC are dominated by the ISM dust emission and bear most resemblance to the tracers of ISM gas rather than the stellar content of the galaxies. We describe the point source extraction processing and the criteria used to establish a catalog for each waveband for the HERITAGE program. The 250 {mu}m band is the most sensitive and the source catalogs for this band have {approx}25,000 objects for the LMC and {approx}5500 objects for the SMC. These data enable studies of ISM dust properties, submillimeter excess dust emission, dust-to-gas ratio, Class 0 YSO candidates, dusty massive evolved stars, supernova remnants (including SN1987A), H II regions, and dust evolution in the LMC and SMC. All images and catalogs are delivered to the Herschel Science Center as part of the community support

  7. The Galaxy-Halo Connection in High-redshift Universe: Details and Evolution of Stellar-to-halo Mass Ratios of Lyman Break Galaxies on CFHTLS Deep Fields

    Science.gov (United States)

    Ishikawa, Shogo; Kashikawa, Nobunari; Toshikawa, Jun; Tanaka, Masayuki; Hamana, Takashi; Niino, Yuu; Ichikawa, Kohei; Uchiyama, Hisakazu

    2017-05-01

    We present the results of clustering analyses of Lyman break galaxies (LBGs) at z˜ 3, 4, and 5 using the final data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). Deep- and wide-field images of the CFHTLS Deep Survey enable us to obtain sufficiently accurate two-point angular correlation functions to apply a halo occupation distribution analysis. The mean halo masses, calculated as ={10}11.7{--}{10}12.8 {h}-1 {M}⊙ , increase with the stellar-mass limit of LBGs. The threshold halo mass to have a central galaxy, {M}\\min , follows the same increasing trend as the low-z results, whereas the threshold halo mass to have a satellite galaxy, M 1, shows higher values at z=3{--}5 than z=0.5{--}1.5, over the entire stellar mass range. Satellite fractions of dropout galaxies, even at less massive halos, are found to drop sharply, from z = 2 down to less than 0.04, at z=3{--}5. These results suggest that satellite galaxies form inefficiently within dark halos at z=3{--}5, even for less massive satellites with {M}\\star pivot}, which is the halo mass at a peak in the star-formation efficiency, at 3 3. In addition, {M}{{h}}{pivot} and its normalization are found to be almost unchanged during 0< z< 5. Our study provides observational evidence that galaxy formation is ubiquitously most efficient near a halo mass of {M}{{h}}˜ {10}12 {M}⊙ over cosmic time.

  8. Precise clustering and density evolution of redMaPPer galaxy clusters versus MXXL simulation

    Science.gov (United States)

    Jimeno, Pablo; Broadhurst, Tom; Lazkoz, Ruth; Angulo, Raul; Diego, Jose-Maria; Umetsu, Keiichi; Chu, Ming-chung

    2017-04-01

    We construct a large, redshift-complete sample of distant galaxy clusters by correlating Sloan Digital Sky Survey Data Release 12 redshifts with clusters identified with the red-sequence Matched-filter Probabilistic Percolation (redMaPPer) algorithm. Our spectroscopic completeness is >97 per cent for ≃7000 clusters within the redMaPPer selection limit, z ≤ 0.325, so that our cluster correlation functions are much more precise than earlier work and not suppressed by uncertain photometric redshifts. We derive an accurate power-law mass-richness relation from the observed abundance with respect to the mass function from Millennium XXL (MXXL) simulations, adjusted to the Planck-weighted cosmology. The number density of clusters is found to decline by 20 per cent over the range 0.1 relation, whereas the observed amplitude of the correlation function at = 0.24 exceeds the MXXL prediction by 20 per cent at the ≃2.5σ level. This tension cannot be blamed on spurious, randomly located clusters as this would reduce the correlation amplitude. Full consistency between the correlation function and the abundances is achievable for the pre-Planck values of σ8 = 0.9, Ωm = 0.25 and h = 0.73, matching the improved distance ladder estimate of the Hubble constant.

  9. Arcus: Exploring the Formation and Evolution of Clusters, Galaxies, and Stars

    Science.gov (United States)

    Smith, Randall K.; Arcus Collaboration

    2017-06-01

    The Large Scale Structure (LSS) of the Universe grew via the gravitational collapse of dark matter, but the visible components that trace the LSS-galaxies, groups and clusters-have a more complex history. Their baryons experience shock heating, radiative cooling and feedback from black holes and star formation, which leave faint signatures of hot (T~10^5-10^8 K), metal-enriched gas in the interstellar and intergalactic media (ISM and IGM). While recent Planck and X-ray studies support this scenario, no current mission possesses the instrumentation necessary to provide direct observational evidence for these “missing baryons." Arcus, a proposed MIDEX mission, leverages recent advances in critical-angle transmission (CAT) gratings and silicon pore optics (SPOs), using CCDs with strong Suzaku heritage and electronics based on the Swift mission; both the spacecraft and mission operations reuse highly successful designs. To be launched in 2023, Arcus will be the only observatory capable of studying, in detail, the hot galactic and intergalactic gas-the dominant baryonic component in the present-day Universe and ultimate reservoir of entropy, metals and the output from cosmic feedback. Its superior soft X-ray sensitivity will complement the forthcoming post-Hitomi and Athena calorimeters, which will have comparably high spectral resolution above 2 keV but poorer spectral resolution than XMM or Chandra in the Arcus bandpass.

  10. SERENDIPITOUS DISCOVERY OF A MASSIVE cD GALAXY AT z = 1.096: IMPLICATIONS FOR THE EARLY FORMATION AND LATE EVOLUTION OF cD GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Liu, F. S. [College of Physical Science and Technology, Shenyang Normal University, Shenyang 110034 (China); Guo Yicheng; Koo, David C.; Trump, Jonathan R.; Barro, Guillermo; Yesuf, Hassen; Faber, S. M.; Cheung, Edmond [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Giavalisco, M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Cassata, P. [Aix Marseille Universite, CNRS, LAM-Laboratoire d' Astrophysique de Marseille, F-13388 Marseille (France); Koekemoer, A. M.; Grogin, Norman A. [Space Telescope Science Institute, 3700 San Martin Boulevard, Baltimore, MD 21218 (United States); Pentericci, L.; Castellano, M. [INAF Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio (RM) (Italy); Mao, Shude [National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Beijing 100012 (China); Xia, X. Y. [Tianjin Astrophysics Center, Tianjin Normal University, Tianjin 300387 (China); Hathi, Nimish P. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Huang, Kuang-Han [Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Kocevski, Dale [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); McGrath, Elizabeth J., E-mail: fengshan@ucolick.org [Department of Physics and Astronomy, Colby College, Mayflower Hill Drive, Waterville, ME 0490 (United States); and others

    2013-06-01

    We have made a serendipitous discovery of a massive ({approx}5 Multiplication-Sign 10{sup 11} M{sub Sun }) cD galaxy at z = 1.096 in a candidate-rich cluster in the Hubble Ultra Deep Field (HUDF) area of GOODS-South. This brightest cluster galaxy (BCG) is the most distant cD galaxy confirmed to date. Ultra-deep HST/WFC3 images reveal an extended envelope starting from {approx}10 kpc and reaching {approx}70 kpc in radius along the semimajor axis. The spectral energy distributions indicate that both its inner component and outer envelope are composed of an old, passively evolving (specific star formation rate <10{sup -4} Gyr{sup -1}) stellar population. The cD galaxy lies on the same mass-size relation as the bulk of quiescent galaxies at similar redshifts. The cD galaxy has a higher stellar mass surface density ({approx}M{sub *}/R{sub 50}{sup 2}) but a similar velocity dispersion ({approx}{radical}(M{sub *}/R{sub 50})) to those of more massive, nearby cDs. If the cD galaxy is one of the progenitors of today's more massive cDs, its size (R{sub 50}) and stellar mass have had to increase on average by factors of 3.4 {+-} 1.1 and 3.3 {+-} 1.3 over the past {approx}8 Gyr, respectively. Such increases in size and stellar mass without being accompanied by significant increases in velocity dispersion are consistent with evolutionary scenarios driven by both major and minor dissipationless (dry) mergers. If such cD envelopes originate from dry mergers, our discovery of even one example proves that some BCGs entered the dry merger phase at epochs earlier than z = 1. Our data match theoretical models which predict that the continuance of dry mergers at z < 1 can result in structures similar to those of massive cD galaxies seen today. Moreover, our discovery is a surprise given that the extreme depth of the HUDF is essential to reveal such an extended cD envelope at z > 1 and, yet, the HUDF covers only a minuscule region of sky ({approx}3.1 Multiplication-Sign 10{sup -8

  11. Are High-redshift Galaxies Hot? Temperature of z > 5 Galaxies and Implications for Their Dust Properties

    Science.gov (United States)

    Faisst, Andreas L.; Capak, Peter L.; Yan, Lin; Pavesi, Riccardo; Riechers, Dominik A.; Barišić, Ivana; Cooke, Kevin C.; Kartaltepe, Jeyhan S.; Masters, Daniel C.

    2017-09-01

    Recent studies have found a significant evolution and scatter in the relationship between the UV spectral slope (β UV) and the infrared excess (IRX; L IR/L UV) at z > 4, suggesting different dust properties of these galaxies. The total far-infrared (FIR) luminosity is key for this analysis, but it is poorly constrained in normal (main-sequence) star-forming z > 5 galaxies, where often only one single FIR point is available. To better inform estimates of the FIR luminosity, we construct a sample of local galaxies and three low-redshift analogues of z > 5 systems. The trends in this sample suggest that normal high-redshift galaxies have a warmer infrared (IR) spectral energy distribution (SED) compared to average z total FIR luminosities, which removes some tension between the dust attenuation models and observations of the IRX-β relation at z > 5. Despite this, some galaxies still fall below the minimum IRX-β relation derived with standard dust cloud models. We propose that radiation pressure in these highly star-forming galaxies causes a spatial offset between dust clouds and young star-forming regions within the lifetime of O/B stars. These offsets change the radiation balance and create viewing-angle effects that can change UV colors at fixed IRX. We provide a modified model that can explain the location of these galaxies on the IRX-β diagram.

  12. Classic Galaxy with Glamour

    Science.gov (United States)

    2005-01-01

    This color composite image of nearby NGC 300 combines the visible-light pictures from Carnegie Institution of Washington's 100-inch telescope at Las Campanas Observatory (colored red and yellow), with ultraviolet views from NASA's Galaxy Evolution Explorer. Galaxy Evolution Explorer detectors image far ultraviolet light (colored blue). This composite image traces star formation in progress. Young hot blue stars dominate the outer spiral arms of the galaxy, while the older stars congregate in the nuclear regions which appear yellow-green. Gases heated by hot young stars and shocks due to winds from massive stars and supernova explosions appear in pink, as revealed by the visible-light image of the galaxy. Located nearly 7 million light years away, NGC 300 is a member of a nearby group of galaxies known as the Sculptor Group. It is a spiral galaxy like our own Milky Way.

  13. Tracking Galaxy Evolution Through Low-Frequency Radio Continuum Observations using SKA and Citizen-Science Research using Multi-Wavelength Data

    Science.gov (United States)

    Hota, Ananda; Konar, C.; Stalin, C. S.; Vaddi, Sravani; Mohanty, Pradeepta K.; Dabhade, Pratik; Dharmik Bhoga, Sai Arun; Rajoria, Megha; Sethi, Sagar

    2016-12-01

    We present a brief review of progress in the understanding of general spiral and elliptical galaxies, through merger, star formation and AGN activities. With reference to case studies performed with the GMRT, we highlight the unique aspects of studying galaxies in the radio wavelengths where powerful quasars and bright radio galaxies are traditionally the dominating subjects. Though AGN or quasar activity is extremely energetic, it is extremely short-lived. This justify focussing on transitional galaxies to find relic-evidences of the immediate past AGN-feedback which decide the future course of evolution of a galaxy. Relic radio lobes can be best detected in low frequency observations with the GMRT, LOFAR and in future SKA. The age of these relic radio plasma can be as old as a few hundred Myr. There is a huge gap between this and what is found in optical bands. The very first relic-evidences of a past quasar activity (Hanny's Voorwerp) was discovered in 2007 by a Galaxy Zoo citizen-scientist, a school teacher, in the optical bands. This relic is around a few tens of thousand years old. More discoveries needed to match these time-scales with star formation time-scales in AGN host galaxies to better understand black hole galaxy co-evolution process via feedback-driven quenching of star formation. It is now well-accepted that discovery and characterization of such faint fuzzy relic features can be more efficiently done by human eye than a machine. Radio interferometry images are more complicated than optical and need the citizen-scientists to be trained. RAD@home, the only Indian citizen-science research project in astronomy, analysing TIFR GMRT Sky Survey (TGSS) 150 MHz data and observing from the Giant Meterwave Radio Telescope (GMRT), was launched in April 2013. Unique, zero-infrastructure zero-funded design of RAD@home as a collaboratory of 69 trained e-astronomers is briefly described. Some of the new-found objects like episodic radio galaxies, radio-jet and

  14. Arcus: exploring the formation and evolution of clusters, galaxies, and stars

    Science.gov (United States)

    Smith, R. K.; Abraham, M.; Allured, R.; Bautz, M.; Bookbinder, J.; Bregman, J.; Brenneman, L.; Brickhouse, N. S.; Burrows, D.; Burwitz, V.; Cheimets, P. N.; Costantini, E.; Dawson, S.; DeRoo, C.; Falcone, A.; Foster, A. R.; Gallo, L.; Grant, C. E.; Günther, H. M.; Heilmann, R. K.; Hertz, E.; Hine, B.; Huenemoerder, D.; Kaastra, J. S.; Kreykenbohm, I.; Madsen, K. K.; McEntaffer, R.; Miller, E.; Miller, J.; Morse, E.; Mushotzky, R.; Nandra, K.; Nowak, M.; Paerels, F.; Petre, R.; Poppenhaeger, K.; Ptak, A.; Reid, P.; Sanders, J.; Schattenburg, M.; Schulz, N.; Smale, A.; Temi, P.; Valencic, L.; Walker, S.; Willingale, R.; Wilms, J.; Wolk, S. J.

    2017-08-01

    Arcus, a Medium Explorer (MIDEX) mission, was selected by NASA for a Phase A study in August 2017. The observatory provides high-resolution soft X-ray spectroscopy in the 12-50Å bandpass with unprecedented sensitivity: effective areas of >450 cm2 and spectral resolution >2500. The Arcus key science goals are (1) to measure the effects of structure formation imprinted upon the hot baryons that are predicted to lie in extended halos around galaxies, groups, and clusters, (2) to trace the propagation of outflowing mass, energy, and momentum from the vicinity of the black hole to extragalactic scales as a measure of their feedback and (3) to explore how stars, circumstellar disks and exoplanet atmospheres form and evolve. Arcus relies upon the same 12m focal length grazing-incidence silicon pore X-ray optics (SPO) that ESA has developed for the Athena mission; the focal length is achieved on orbit via an extendable optical bench. The focused X-rays from these optics are diffracted by high-efficiency Critical-Angle Transmission (CAT) gratings, and the results are imaged with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. Mission operations are straightforward, as most observations will be long ( 100 ksec), uninterrupted, and pre-planned, although there will be capabilities to observe sources such as tidal disruption events or supernovae with a 3 day turnaround. Following the 2nd year of operation, Arcus will transition to a proposal-driven guest observatory facility.

  15. GAS REGULATION OF GALAXIES: THE EVOLUTION OF THE COSMIC SPECIFIC STAR FORMATION RATE, THE METALLICITY-MASS-STAR-FORMATION RATE RELATION, AND THE STELLAR CONTENT OF HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Lilly, Simon J.; Carollo, C. Marcella; Pipino, Antonio; Peng Yingjie [Institute for Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Renzini, Alvio [Department of Physics and Astronomy Galileo Galilei, Universita degli Studi di Padova, via Marzolo 8, I-35131 Padova (Italy)

    2013-08-01

    A very simple physical model of galaxies is one in which the formation of stars is instantaneously regulated by the mass of gas in a reservoir with mass loss scaling with the star-formation rate (SFR). This model links together three different aspects of the evolving galaxy population: (1) the cosmic time evolution of the specific star-formation rate (sSFR) relative to the growth of halos, (2) the gas-phase metallicities across the galaxy population and over cosmic time, and (3) the ratio of the stellar to dark matter mass of halos. The gas regulator is defined by the gas consumption timescale ({epsilon}{sup -1}) and the mass loading {lambda} of the wind outflow {lambda}{center_dot}SFR. The simplest regulator, in which {epsilon} and {lambda} are constant, sets the sSFR equal to exactly the specific accretion rate of the galaxy; more realistic situations lead to an sSFR that is perturbed from this precise relation. Because the gas consumption timescale is shorter than the timescale on which the system evolves, the metallicity Z is set primarily by the instantaneous operation of the regulator system rather than by the past history of the system. The metallicity of the gas reservoir depends on {epsilon}, {lambda}, and sSFR, and the regulator system therefore naturally produces a Z(m{sub star}, SFR) relation if {epsilon} and {lambda} depend on the stellar mass m{sub star}. Furthermore, this relation will be the same at all epochs unless the parameters {epsilon} and {lambda} themselves change with time. A so-called fundamental metallicity relation is naturally produced by these conditions. The overall mass-metallicity relation Z(m{sub star}) directly provides the fraction f{sub star}(m{sub star}) of incoming baryons that are being transformed into stars. The observed Z(m{sub star}) relation of Sloan Digital Sky Survey (SDSS) galaxies implies a strong dependence of stellar mass on halo mass that reconciles the different faint-end slopes of the stellar and halo mass

  16. Modified Covariance Matrix Adaptation – Evolution Strategy algorithm for constrained optimization under uncertainty, application to rocket design

    Directory of Open Access Journals (Sweden)

    Chocat Rudy

    2015-01-01

    Full Text Available The design of complex systems often induces a constrained optimization problem under uncertainty. An adaptation of CMA-ES(λ, μ optimization algorithm is proposed in order to efficiently handle the constraints in the presence of noise. The update mechanisms of the parametrized distribution used to generate the candidate solutions are modified. The constraint handling method allows to reduce the semi-principal axes of the probable research ellipsoid in the directions violating the constraints. The proposed approach is compared to existing approaches on three analytic optimization problems to highlight the efficiency and the robustness of the algorithm. The proposed method is used to design a two stage solid propulsion launch vehicle.

  17. The Herschel* PEP-HERMES Luminosity Function- I. Probing the Evolution of PACS Selected Galaxies to z approx. equal to 4

    Science.gov (United States)

    Gruppioni, Carlotta; Pozzi, F.; Rodighiero, G.; Delvecchio, I.; Berta, S.; Pozzetti, L.; Zamorani, G.; Andreani, P.; Cimatti, A.; Ilbert, O.; hide

    2013-01-01

    We exploit the deep and extended far-IR data sets (at 70, 100 and 160 µm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 µm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z 4.We detect very strong luminosity evolution for the total IR LF (LIR ? (1 + z)(sup 3.55 +/- 0.10) up to z 2, and ? (1 + z)(sup 1.62 +/- 0.51) at 2 less than z less than approximately 4) combined with a density evolution (? (1 + z)(sup -0.57 +/- 0.22) up to z 1 and ? (1 + z)(sup -3.92 +/- 0.34) at 1 less than z less than approximately 4). In agreement with previous findings, the IR luminosity density (?IR) increases steeply to z 1, then flattens between z 1 and z 3 to decrease at z greater than approximately 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ?IR. Galaxies occupying the well-established SFR-stellar mass main sequence (MS) are found to dominate both the total IR LF and ?IR at all redshifts, with the contribution from off-MS sources (=0.6 dex above MS) being nearly constant (20 per cent of the total ?IR) and showing no significant signs of increase with increasing z over the whole 0.8 < z <2.2 range. Sources with mass in the range 10 = log(M/solar mass) = 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (greater than approximately 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event

  18. STATISTICAL PROPERTIES OF GRB AFTERGLOW PARAMETERS AS EVIDENCE OF COSMOLOGICAL EVOLUTION OF THEIR HOST GALAXIES

    Directory of Open Access Journals (Sweden)

    Gregory Beskin

    2014-08-01

    Full Text Available The results of a study of 43 peaked R-band light curves of optical counterparts of gamma-ray bursts with known redshifts are presented. The parameters of optical transients were calculated in the comoving frame, and then a search for pair correlations between them was conducted. A statistical analysis showed a strong correlation between the peak luminosity and the redshift both for pure afterglows and for events with residual gamma activity, which cannot be explained as an effect of observational selection.This suggests a cosmological evolution of the parameters of the local interstellar medium around the sources of the gamma-ray burst. In the models of forward and reverse shock waves, a relation between the density of the interstellar medium and the redshift was built for gamma-ray burst afterglows, leading to a power-law dependence of the star-formation rate at regions around GRBs on redshift with a slope of about 6.

  19. The SAURON project : XV. Modes of star formation in early-type galaxies and the evolution of the red sequence

    NARCIS (Netherlands)

    Shapiro, Kristen L.; Falcon-Barroso, Jesus; van de Ven, Glenn; de Zeeuw, P. Tim; Sarzi, Marc; Bacon, Roland; Bolatto, Alberto; Cappellari, Michele; Croton, Darren; Davies, Roger L.; Emsellem, Eric; Fakhouri, Onsi; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; van den Bosch, Remco C. E.; van der Wolk, Guido

    We combine SAURON integral field data of a representative sample of local early-type, red sequence galaxies with Spitzer/Infrared Array Camera imaging in order to investigate the presence of trace star formation in these systems. With the Spitzer data, we identify galaxies hosting low-level star

  20. The angular momentum of hot coronae around spiral galaxies and its impact on the evolution of star forming discs

    NARCIS (Netherlands)

    Pezzulli, G.; Fraternali, F.; Binney, J.

    Galaxy formation theory and recent observations indicate that spiral galaxies are surrounded by massive and hot coronae, which potentially constitute a huge source of mass and angular momentum for the star forming discs embedded within them. Accretion from these reservoirs is likely a key ingredient

  1. Luminosity evolution of early-type galaxies to z=0.83 : constraints on formation epoch and Omega

    NARCIS (Netherlands)

    van Dokkum, PG; Franx, M; Kelson, DD; Illingworth, GD

    1998-01-01

    We present deep Keck telescope spectroscopy of eight galaxies in the luminous X-ray cluster MS 1054-03 at z = 0.83, The data are combined with imaging observations from the Hubble Space Telescope (HST). The spectroscopic data are used to measure the internal kinematics of the galaxies, and the HST

  2. The SAURON project - XV. Modes of star formation in early-type galaxies and the evolution of the red sequence

    NARCIS (Netherlands)

    Shapiro, Kristen L.; Falcón-Barroso, Jesús; van de Ven, Glenn; de Zeeuw, P. Tim; Sarzi, Marc; Bacon, Roland; Bolatto, Alberto; Cappellari, Michele; Croton, Darren; Davies, Roger L.; Emsellem, Eric; Fakhouri, Onsi; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; van den Bosch, Remco C. E.; van der Wolk, Guido

    We combine SAURON integral field data of a representative sample of local early-type, red sequence galaxies with Spitzer/Infrared Array Camera imaging in order to investigate the presence of trace star formation in these systems. With the Spitzer data, we identify galaxies hosting low-level star

  3. Galaxy evolution. Evidence for mature bulges and an inside-out quenching phase 3 billion years after the Big Bang.

    Science.gov (United States)

    Tacchella, S; Carollo, C M; Renzini, A; Förster Schreiber, N M; Lang, P; Wuyts, S; Cresci, G; Dekel, A; Genzel, R; Lilly, S J; Mancini, C; Newman, S; Onodera, M; Shapley, A; Tacconi, L; Woo, J; Zamorani, G

    2015-04-17

    Most present-day galaxies with stellar masses ≥10(11) solar masses show no ongoing star formation and are dense spheroids. Ten billion years ago, similarly massive galaxies were typically forming stars at rates of hundreds solar masses per year. It is debated how star formation ceased, on which time scales, and how this "quenching" relates to the emergence of dense spheroids. We measured stellar mass and star-formation rate surface density distributions in star-forming galaxies at redshift 2.2 with ~1-kiloparsec resolution. We find that, in the most massive galaxies, star formation is quenched from the inside out, on time scales less than 1 billion years in the inner regions, up to a few billion years in the outer disks. These galaxies sustain high star-formation activity at large radii, while hosting fully grown and already quenched bulges in their cores. Copyright © 2015, American Association for the Advancement of Science.

  4. What Can Galaxies Tell Us About The Epoch of Reionization?

    Science.gov (United States)

    Mason, Charlotte; GLASS, BoRG

    2018-01-01

    The reionization of neutral hydrogen in the intergalactic medium (IGM) in the universe's first billion years (z>6) was likely driven by the first stars and galaxies, and its history encodes information about their properties. But the timeline of reionization is not well-measured and it is still unclear whether galaxies alone can produce the required ionizing photons. I will describe two key ways in which galaxies at our current observational frontiers can constrain reionization.One tool is the UV luminosity function (LF), which traces the evolution of star-forming galaxies and their ionizing photons. I will describe a Bayesian technique to account for gravitational lensing magnification bias in galaxy surveys to produce accurate LFs. I will then describe a simple, but powerful, model for LF evolution and its implications for reionization and z>10 galaxy surveys with JWST. Secondly, Lyman alpha (Lya) emission from galaxies is a potential probe of the IGM ionization state as Lya photons are strongly attenuated by neutral hydrogen, but requires disentangling physics on pc to Gpc scales. I will introduce a new forward-modeling Bayesian framework which combines cosmological IGM simulations with models of interstellar medium conditions to infer the IGM neutral fraction from observations of Lya emission. I will present our new measurement of the neutral fraction at z~7 and place it in the context of other constraints of the reionization history. I will describe ongoing efforts to build larger samples of Lya emitting galaxies for more accurate measurements with the HST survey GLASS, and will describe future prospects with JWST.

  5. Gas accretion onto galaxies

    CERN Document Server

    Davé, Romeel

    2017-01-01

    This edited volume presents the current state of gas accretion studies from both observational and theoretical perspectives, and charts our progress towards answering the fundamental yet elusive question of how galaxies get their gas. Understanding how galaxies form and evolve has been a central focus in astronomy for over a century. These studies have accelerated in the new millennium, driven by two key advances: the establishment of a firm concordance cosmological model that provides the backbone on which galaxies form and grow, and the recognition that galaxies grow not in isolation but within a “cosmic ecosystem” that includes the vast reservoir of gas filling intergalactic space. This latter aspect in which galaxies continually exchange matter with the intergalactic medium via inflows and outflows has been dubbed the “baryon cycle”. The topic of this book is directly related to the baryon cycle, in particular its least well constrained aspect, namely gas accretion. Accretion is a rare area of ast...

  6. Tubulin evolution in insects: gene duplication and subfunctionalization provide specialized isoforms in a functionally constrained gene family

    Directory of Open Access Journals (Sweden)

    Gadagkar Sudhindra R

    2010-04-01

    Full Text Available Abstract Background The completion of 19 insect genome sequencing projects spanning six insect orders provides the opportunity to investigate the evolution of important gene families, here tubulins. Tubulins are a family of eukaryotic structural genes that form microtubules, fundamental components of the cytoskeleton that mediate cell division, shape, motility, and intracellular trafficking. Previous in vivo studies in Drosophila find a stringent relationship between tubulin structure and function; small, biochemically similar changes in the major alpha 1 or testis-specific beta 2 tubulin protein render each unable to generate a motile spermtail axoneme. This has evolutionary implications, not a single non-synonymous substitution is found in beta 2 among 17 species of Drosophila and Hirtodrosophila flies spanning 60 Myr of evolution. This raises an important question, How do tubulins evolve while maintaining their function? To answer, we use molecular evolutionary analyses to characterize the evolution of insect tubulins. Results Sixty-six alpha tubulins and eighty-six beta tubulin gene copies were retrieved and subjected to molecular evolutionary analyses. Four ancient clades of alpha and beta tubulins are found in insects, a major isoform clade (alpha 1, beta 1 and three minor, tissue-specific clades (alpha 2-4, beta 2-4. Based on a Homarus americanus (lobster outgroup, these were generated through gene duplication events on major beta and alpha tubulin ancestors, followed by subfunctionalization in expression domain. Strong purifying selection acts on all tubulins, yet maximum pairwise amino acid distances between tubulin paralogs are large (0.464 substitutions/site beta tubulins, 0.707 alpha tubulins. Conversely orthologs, with the exception of reproductive tissue isoforms, show little sequence variation except in the last 15 carboxy terminus tail (CTT residues, which serve as sites for post-translational modifications (PTMs and interactions

  7. Confronting semi-analytic galaxy models with galaxy-matter correlations observed by CFHTLenS

    Science.gov (United States)

    Saghiha, Hananeh; Simon, Patrick; Schneider, Peter; Hilbert, Stefan

    2017-05-01

    Testing predictions of semi-analytic models of galaxy evolution against observations helps to understand the complex processes that shape galaxies. We compare predictions from the Garching and Durham models implemented on the Millennium Simulation (MS) with observations of galaxy-galaxy lensing (GGL) and galaxy-galaxy-galaxy lensing (G3L) for various galaxy samples with stellar masses in the range 0.5 ≤ M∗/ 1010M⊙ Durham models are strongly excluded by the observations at the 95% confidence level because they largely over-predict the amplitudes of the GGL and G3L signals, probably because they predict too many satellite galaxies in massive halos.

  8. Cretaceous to Miocene fault zone evolution in the Eastern Alps constrained by multi-system thermochronometry and structural data.

    Science.gov (United States)

    Wölfler, Andreas; Frisch, Wolfgang; Danišík, Martin; Fritz, Harald; Wölfler, Anke

    2015-04-01

    Fault zones that display both, ductile and brittle deformation stages offer perfect sites to study the evolution of the earth's crust over a wide range of temperatures and possibly over long time spans. This study combines structural- geo- and thermochronologcial data to evaluate the tectonic evolution of a fault zone to the southeast of the Tauern Window in the Eastern Alps. This fault zone comprises a mylonitic part, the so-called "Main Mylonitic Zone" (MMZ) that has been reworked by brittle faulting, the so-called "Ragga-Teuchl fault" (RTF). Structural data of the MMZ demonstrate ductile deformation with top-to-the NW transport in the Late Cretaceous under greenschist facies conditions. Subsequent SE-directed extension occurred under semi-brittle to brittle conditions during the Late Cretaceous and Paleocene. The Polinik Block to the north of the RTF revealed Late Cretaceous Ar/Ar ages, which reflect cooling subsequent to the thermal peak of Eo-alpine metamorphism. In contrast, the Kreuzeck Block to the south of the RTF shows early Permian Ar/Ar ages that reflect cooling related to both, late Variscan collapse in the late Carboniferous and post-Variscan extension in the Permian. Zircon and apatite fission track ages and thermal history modeling results suggest that the Polinik Block cooled rapidly to near surface temperatures in the middle Miocene. The Kreuzeck Block, in contrast, cooled and exhumed to near surface conditions already in the Oligocene and early Miocene. Thermal history modeling and apatite fission track ages of 23.3±0.8 and 11.5±1.0 suggest that brittle deformation along the RTF occurred in the middle- and late Miocene. Our results demonstrate that one single fault zone may comprise information about the evolution of the Eastern Alps from Late Cretaceous to Miocene time and that low-temperature thermochronology is a viable tool to resolve the timing of brittle faulting and accompanied fluid activity.

  9. Mosfire Spectroscopy Of Galaxies In Cosmic Noon

    Science.gov (United States)

    Nanayakkara, Themiya

    2017-07-01

    differences of the z ˜ 2 sample with that of local galaxies are found to be intriguing. Further study is required to fully constrain the stellar population parameters of actively star-forming galaxies at the epoch of maximum star-formation. Probing multiple rest-frame UV and optical features of galaxies simultaneously along with galaxy dynamical studies via integral field spectroscopy will be vital to understand stellar and ionized gas properties of these galaxies. Furthermore, low-z analogues of galaxies at z ˜ 2 will provide vital clues to constrain galaxy evolution models aided by the ability to probe galaxies in high resolution to low surface brightness limits.

  10. New Constraints on the Evolution of the Stellar-to-dark Matter Connection: A Combined Analysis of Galaxy-Galaxy Lensing, Clustering, and Stellar Mass Functions from z = 0.2 to z =1

    Science.gov (United States)

    Leauthaud, Alexie; Tinker, Jeremy; Bundy, Kevin; Behroozi, Peter S.; Massey, Richard; Rhodes, Jason; George, Matthew R.; Kneib, Jean-Paul; Benson, Andrew; Wechsler, Risa H.; Busha, Michael T.; Capak, Peter; Cortês, Marina; Ilbert, Olivier; Koekemoer, Anton M.; Le Fèvre, Oliver; Lilly, Simon; McCracken, Henry J.; Salvato, Mara; Schrabback, Tim; Scoville, Nick; Smith, Tristan; Taylor, James E.

    2012-01-01

    Using data from the COSMOS survey, we perform the first joint analysis of galaxy-galaxy weak lensing, galaxy spatial clustering, and galaxy number densities. Carefully accounting for sample variance and for scatter between stellar and halo mass, we model all three observables simultaneously using a novel and self-consistent theoretical framework. Our results provide strong constraints on the shape and redshift evolution of the stellar-to-halo mass relation (SHMR) from z = 0.2 to z = 1. At low stellar mass, we find that halo mass scales as Mh vpropM 0.46 * and that this scaling does not evolve significantly with redshift from z = 0.2 to z = 1. The slope of the SHMR rises sharply at M * > 5 × 1010 M ⊙ and as a consequence, the stellar mass of a central galaxy becomes a poor tracer of its parent halo mass. We show that the dark-to-stellar ratio, Mh /M *, varies from low to high masses, reaching a minimum of Mh /M * ~ 27 at M * = 4.5 × 1010 M ⊙ and Mh = 1.2 × 1012 M ⊙. This minimum is important for models of galaxy formation because it marks the mass at which the accumulated stellar growth of the central galaxy has been the most efficient. We describe the SHMR at this minimum in terms of the "pivot stellar mass," M piv *, the "pivot halo mass," M piv h , and the "pivot ratio," (Mh /M *)piv. Thanks to a homogeneous analysis of a single data set spanning a large redshift range, we report the first detection of mass downsizing trends for both M piv h and M piv *. The pivot stellar mass decreases from M piv * = 5.75 ± 0.13 × 1010 M ⊙ at z = 0.88 to M piv * = 3.55 ± 0.17 × 1010 M ⊙ at z = 0.37. Intriguingly, however, the corresponding evolution of M piv h leaves the pivot ratio constant with redshift at (Mh /M *)piv ~ 27. We use simple arguments to show how this result raises the possibility that star formation quenching may ultimately depend on Mh /M * and not simply on Mh , as is commonly assumed. We show that simple models with such a dependence

  11. The tree balance signature of mass extinction is erased by continued evolution in clades of constrained size with trait-dependent speciation.

    Science.gov (United States)

    Yang, Guan-Dong; Agapow, Paul-Michael; Yedid, Gabriel

    2017-01-01

    The kind and duration of phylogenetic topological "signatures" left in the wake of macroevolutionary events remain poorly understood. To this end, we examined a broad range of simulated phylogenies generated using trait-biased, heritable speciation probabilities and mass extinction that could be either random or selective on trait value, but also using background extinction and diversity-dependence to constrain clade sizes. In keeping with prior results, random mass extinction increased imbalance of clades that recovered to pre-extinction size, but was a relatively weak effect. Mass extinction that was selective on trait values tended to produce clades of similar or greater balance compared to random extinction or controls. Allowing evolution to continue past the point of clade-size recovery resulted in erosion and eventual erasure of this signal, with all treatments converging on similar values of imbalance, except for very intense extinction regimes targeted at taxa with high speciation rates. Return to a more balanced state with extended post-extinction evolution was also associated with loss of the previous phylogenetic root in most treatments. These results further demonstrate that while a mass extinction event can produce a recognizable phylogenetic signal, its effects become increasingly obscured the further an evolving clade gets from that event, with any sharp imbalance due to unrelated evolutionary factors.

  12. Investigating early-type galaxy evolution with a multiwavelength approach - I. X-ray properties of 12 galaxies observed with Swift and XMM-Newton

    Science.gov (United States)

    Trinchieri, G.; Rampazzo, R.; Mazzei, P.; Marino, A.; Wolter, A.

    2015-05-01

    We report here the results from the X-ray observations of 12 early-type galaxies (ETGs) observed with Swift and XMM-Newton, originally selected from a sample of galaxies with Spitzer and/or GALEX data. With the combined analysis of new X-ray and optical-UV observations and of previously available data from archives, we aim at investigating the relation between X-ray luminosity and evolutionary phases of ETGs. We will interpret the results with the additional aid of smoothed particle hydrodynamics chemo-photometric simulations. All galaxies have been detected in the X-ray band, with luminosities Lx > 1039 erg s-1. X-ray emitting gas has been detected in about half of the sample, with luminosities from ≥1039 to 1040 erg s-1. UVOT images show a variety of morphologies, from absence of peculiar features relative to optical wavelengths typical of red and dead early-types, to well defined almost circular rings clearly emerging in the U band, to more spectacular and complex features connected to recent or even ongoing star formation (SF). We find little evidence of any influence of the SF activity on their global X-ray properties, and in particular, on the luminosity-weighted age of the system, usually estimated in the nuclear region. However, with the present data we cannot exclude that such a relation exists on smaller scales, related to the specific sites where we see evidence of newly formed stars, such as outer rings and arcs and peculiar features observed in UV images.

  13. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: The redshift distribution and evolution of submillimeter galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, J. M.; Swinbank, A. M.; Smail, Ian; Alexander, D. M.; Danielson, A. L. R.; Thomson, A. P. [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Bertoldi, F.; Karim, A. [Argelander-Institute for Astronomy, Bonn University, Auf dem Hügel 71, D-53121 Bonn (Germany); De Breuck, C. [European Southern Observatory, Karl-Schwarzschild Straße, D-85748 Garching bei München (Germany); Chapman, S. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 (Canada); Coppin, K. E. K. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Da Cunha, E.; Hodge, J. A.; Schinnerer, E. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Dannerbauer, H. [Universität Wien, Institut für Astrophysik, Türkenschanzstraße 17, A-1180 Wien (Austria); Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Ivison, R. J. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Knudsen, K. K. [Department of Earth and Space Science, Onsala Space Observatory, Chalmers University of Technology, SE-43992 Onsala (Sweden); Poggianti, B. M., E-mail: j.m.simpson@dur.ac.uk [INAF-Astronomical Observatory of Padova, I-35122 Padova (Italy); and others

    2014-06-20

    We present the first photometric redshift distribution for a large sample of 870 μm submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z {sub phot} = 2.3 ± 0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z ∼ 1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z {sub phot} = 2.5 ± 0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z ≥ 3 is at most 35% ± 5% of the total population. We derive a median stellar mass of M {sub *} = (8 ± 1) × 10{sup 10} M {sub ☉}, although there are systematic uncertainties of up to 5 × for individual sources. Assuming that the star formation activity in SMGs has a timescale of ∼100 Myr, we show that their descendants at z ∼ 0 would have a space density and M{sub H} distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.

  14. The galaxy ancestor problem

    Science.gov (United States)

    Disney, M. J.; Lang, R. H.

    2012-11-01

    The Hubble Space Telescope (HST) findsgalaxies whose Tolman dimming exceeds 10 mag. Could evolution alone explain these as our ancestor galaxies or could they be representatives of quite a different dynasty whose descendants are no longer prominent today? We explore the latter hypothesis and argue that surface brightness selection effects naturally bring into focus quite different dynasties from different redshifts. Thus, the HST z = 7 galaxies could be examples of galaxies whose descendants are both too small and too choked with dust to be recognizable in our neighbourhood easily today. Conversely, the ancestors of the Milky Way and its obvious neighbours would have completely sunk below the sky at z > 1.2, unless they were more luminous in the past, although their diffused light could account for the missing re-ionization flux. This Succeeding Prominent Dynasties Hypothesis (SPDH) fits the existing observations both naturally and well even without evolution, including the bizarre distributions of galaxy surface brightness found in deep fields, the angular size ˜(1 + z)-1 law, 'downsizing' which turns out to be an 'illusion' in the sense that it does not imply evolution, 'infant mortality', that is, the discrepancy between stars born and stars seen, the existence of 'red nuggets', and finally the recently discovered and unexpected excess of quasar absorption line damped Lyα systems at high redshift. If galaxies were not significantly brighter in the past and the SPDH were true, then a large proportion of galaxies could remain sunk from sight, possibly at all redshifts, and these sunken galaxies could supply the missing re-ionization flux. We show that fishing these sunken galaxies out of the sky by their optical emissions alone is practically impossible, even when they are nearby. More ingenious methods are needed to detect them. It follows that disentangling galaxy evolution through studying ever higher redshift galaxies may be a forlorn hope because one could

  15. ATLASGAL-selected massive clumps in the inner Galaxy. V. Temperature structure and evolution

    Science.gov (United States)

    Giannetti, A.; Leurini, S.; Wyrowski, F.; Urquhart, J.; Csengeri, T.; Menten, K. M.; König, C.; Güsten, R.

    2017-07-01

    Context. Observational identification of a solid evolutionary sequence for high-mass star-forming regions is still missing. Spectroscopic observations give the opportunity to test possible schemes and connect the phases identified to physical processes. Aims: We aim to use the progressive heating of the gas caused by the feedback of high-mass young stellar objects to prove the statistical validity of the most common schemes used to observationally define an evolutionary sequence for high-mass clumps, and characterise the sensitivity of different tracers to this process. Methods: From the spectroscopic follow-ups carried out towards submillimeter continuum (dust) emission-selected massive clumps (the ATLASGAL TOP100 sample) with the IRAM 30 m, Mopra, and APEX telescopes between 84 GHz and 365 GHz, we selected several multiplets of CH3CN, CH3CCH, and CH3OH emission lines to derive and compare the physical properties of the gas in the clumps along the evolutionary sequence, fitting simultaneously the large number of lines that these molecules have in the observed band. Our findings are compared with results obtained from optically thin CO isotopologues, dust, and ammonia from previous studies on the same sample. Results: The chemical properties of each species have a major role on the measured physical properties. Low temperatures are traced by ammonia, methanol, and CO (in the early phases), the warm and dense envelope can be probed with CH3CN, CH3CCH, and, in evolved sources where CO is abundant in the gas phase, via its optically thin isotopologues. CH3OH and CH3CN are also abundant in the hot cores, and we suggest that their high-excitation transitions are good tools to study the kinematics in the hot gas associated with the inner envelope surrounding the young stellar objects that these clumps are hosting. All tracers show, to different degrees according to their properties, progressive warming with evolution. The relation between gas temperature and the

  16. A Bayesian approach to constrain the time evolution of tropospheric parameters in GNSS data processing : implications for meteorology

    Science.gov (United States)

    Nahmani, S.; Rebischung, P.; Bock, O.

    2016-12-01

    The atmospheric water vapor induces a delay in the propagation time of GNSS signals when they cross the troposphere. Zenithal Wet Delays (ZWD) are thus estimated during GNSS data processing and used to retrieve Integrated Water Vapor (IWV) with a usual precision of around 1-2 kg.m-2. These GNSS-derived IWV are now routinely assimilated into numerical weather prediction models and are also used to validate satellite measurements and evaluate climate models. However, their accuracy remains to be precisely evaluated especially during intense weather events. Developing and evaluating advanced tropospheric products for monitoring severe weather events and climate is one of the main objectives of the COST Action ES1206 supported by the EU.In this study, we focus on a particular limitation of GNSS-derived IWV: in GNSS data processing, the temporal evolution of ZWD is usually modelled as a random walk (ZWD(t+dt) = ZWD(t) + ɛ(t)), where the variance of the white noise ɛ(t) is usually chosen arbitrarily, regardless of the location of the station and the local weather conditions. This approach is clearly not optimal, for instance in case of severe weather events, where an inappropriate variance choice for ɛ(t) can induce biases over 5 kg.m-2 on GNSS-derived IWV. We therefore use a Bayesian approach to determine optimal random walk variances for both ZWD and tropospheric gradients in PPP processing of GNSS data. We first present the methodology and validate it with simulated data. Then, we apply our method on real GNSS data and compare the obtained ZWD with those from a usual PPP processing. Finally, we plan to use data from microwave radiometers to get an external characterization of the temporal evolution of ZWD and to verify that the random walk variances obtained with our method adequately describe the variability of atmospheric water vapor.

  17. An Atlas of Galaxy Spectral Energy Distributions from the Ultraviolet to the Mid-infrared

    Science.gov (United States)

    Brown, Michael J. I.; Moustakas, John; Smith, J.-D. T.; da Cunha, Elisabete; Jarrett, T. H.; Imanishi, Masatoshi; Armus, Lee; Brandl, Bernhard R.; Peek, J. E. G.

    2014-06-01

    We present an atlas of 129 spectral energy distributions for nearby galaxies, with wavelength coverage spanning from the ultraviolet to the mid-infrared. Our atlas spans a broad range of galaxy types, including ellipticals, spirals, merging galaxies, blue compact dwarfs, and luminous infrared galaxies. We have combined ground-based optical drift-scan spectrophotometry with infrared spectroscopy from Spitzer and Akari with gaps in spectral coverage being filled using Multi-wavelength Analysis of Galaxy Physical Properties spectral energy distribution models. The spectroscopy and models were normalized, constrained, and verified with matched-aperture photometry measured from Swift, Galaxy Evolution Explorer, Sloan Digital Sky Survey, Two Micron All Sky Survey, Spitzer, and Wide-field Infrared Space Explorer images. The availability of 26 photometric bands allowed us to identify and mitigate systematic errors present in the data. Comparison of our spectral energy distributions with other template libraries and the observed colors of galaxies indicates that we have smaller systematic errors than existing atlases, while spanning a broader range of galaxy types. Relative to the prior literature, our atlas will provide improved K-corrections, photometric redshifts, and star-formation rate calibrations.

  18. The relationships between galaxies/AGN and the circum-/intergalactic medium at z<1

    Science.gov (United States)

    Johnson, Sean; Chen, Hsiao-Wen; Mulchaey, John S.

    2016-01-01

    The growth and evolution of galaxies is governed by gas accretion from circum-/intergalactic gas reservoirs and satellites that is regulated by feedback from stars and active galactic nuclei. To constrain the relationship between these gas reservoirs and galaxy properties, I have carried out deep and highly complete surveys of several thousand galaxies in fields with high quality absorption spectra of background quasars from the Cosmic Origins Spectrograph. The survey results imply that (1) highly ionized, heavy-element enriched gas traced by OVI absorption primarily arise in low-mass, gas-rich galaxy groups rather than the warm-hot phase of the intergalactic medium and that (2) galaxies with nearby neighbors exhibit more extened OVI absorbing gas than isolated galaxies. Together, these observations suggest that galaxy and group interactions play a role in stripping bound, heavy element enriched halo gas to enrich the intergalactic medium. In addition, I carried out the first large survey of circumgalactic gas around active galactic nuclei (AGN) and quasars. The cool, heavy-element enriched gas content of AGN and quasar host halos is strongly correlated with AGN luminosity, and the gas exhibit extreme kinematics with velocity spread inconsistent with gas bound to the AGN host. These observations provide tantalizing hints at the widespread impact of AGN feedback on the extended gas reservoirs around galaxies.

  19. Post-Variscan evolution of the Anti-Atlas belt of Morocco constrained from low-temperature geochronology

    Science.gov (United States)

    Gouiza, M.; Charton, R.; Bertotti, G.; Andriessen, P.; Storms, J. E. A.

    2017-03-01

    The Anti-Atlas belt of Morocco extends ENE-WSW, over more than 600 km, from the Atlantic margin in the west to the interior of the African plate in the east. It exhibits Precambrian rocks outcropping as basement inliers and surrounded by marine Ediacaran-Cambrian sequences around the axis of the mountain range. The belt, which has for a long time been interpreted as of Variscan age, is now revealed to have experienced major vertical movements through Mesozoic and Cenozoic times. Thereby, the Anti-Atlas domain appears to be affected by two episodes of exhumation separated by an episode of subsidence. The initial episode occurred in the Late Triassic and led to the exhumation of 7.5-10.5 km of crustal rocks by the end of the Middle Jurassic (ca. 160-150 Ma). The following phase resulted in 1-3 km of basement subsidence and occurred during the Late Jurassic and most of the Early Cretaceous. The basement rocks were then slowly brought to the surface after experiencing 2-3.5 km of exhumation throughout the Late Cretaceous and the Cenozoic. The timing of these episodes of exhumation and subsidence coincides with major tectonic and thermal events in relation with the evolution of the Atlantic and Tethys Oceans, indicating that the effects of their rifting and drifting extended beyond their presumed margins.

  20. Revolutionizing Our Understanding of AGN Feedback and its Importance to Galaxy Evolution in the Era of the Next Generation Very Large Array

    Science.gov (United States)

    Nyland, Kristina; Harwood, Jeremy; Jagannathan, Preshanth; Mukherjee, Dipanjan; Lacy, Mark; Morabito, Leah; Maksym, W. Peter; Kimball, Amy; Alatalo, Katherine; Bicknell, Geoff; Patil, Pallavi; Emonts, Bjorn

    2018-01-01

    Energetic feedback by Active Galactic Nuclei (AGNs) likely plays an important evolutionary role in the regulation of star formation (SF) on galactic scales. However, the effects of this feedback under different host galaxy conditions and environments remain unknown due to the scarcity of observational examples of this process in action given the limitations of current telescopes. The Next Generation Very Large Array (ngVLA) will serve as a transformational new tool in our understanding of how radio jets affect their surroundings. Current plans for the ngVLA consist of an array of 214 18m antennas with baselines out to 500 km operating over a frequency range of 1-115 GHz. By combining deep, broadband continuum data with measurements of the atomic and/or molecular gas content and kinematics, the ngVLA will quantify the energetic impact of radio jets hosted by gas-rich galaxies as the jets interact with the star-forming gas reservoirs of their hosts. Here, we evaluate the progress in our understanding of AGN feedback and its connection to galaxy evolution that may be accomplished with the unique capabilities of the ngVLA. Our analysis includes simulations of ngVLA observations of redshifted analogs of nearby AGNs with diverse properties, along with examples of opportunities for multiwavelength synergies with current and future next-generation instruments that are currently under development.

  1. The Galex Large Galaxy Atlas (glga)

    Science.gov (United States)

    Seibert, Mark

    GALEX surveys contain the most comprehensive collection of UV imaged extended galaxies likely to exist for decades. Unfortunately, with the exception of the 1,000 galaxies contained in the Nearby Galaxy Atlas (NGA), this impressive resource is under-utilized because 1) the pipeline-generated source catalogs split extended objects into many pieces (""shredding"") and 2) co-adding of data using multiple survey types is not regularly performed. We propose to solve both of these problems by constructing the GALEX Large Galaxy Atlas (GLGA) using all observations of galaxies with diameters of at least 1 arcmin, make it available to the public via the NASA/IPAC Extragalactic Database (NED), and provide our software for the co-adding and mosaicing of GALEX data to the astronomical community. The GLGA will build upon and extend the NGA in three significant ways; it will 1) contain 21,000 galaxies, 2) co-add data from multiple survey types, and 3) preserve multi-epoch observations to facilitate time domain studies. Extending the NGA to 21,000 galaxies will be a major contribution to the legacy of GALEX. Although the GLGA will be a tremendous resource available to anyone, our team was inspired to its construction for several projects. We will use the GLGA to measure proper UV-optical-NIR colors for a large sample of extended galaxies for the first time. This is a critical step for locating examples of nearby ``green-valley"" or transition galaxies which may be the best objects for understanding blue-red sequence evolution. We are compiling a matching catalog of HI single dish fluxes and images with the goal of using it to study the detailed relationship between gas content and star formation rate, implications for star formation ``laws'' and the triggering and quenching of star formation. Finally, we are compiling IRAS HiRes data for objects with diameters >2 arcmin with the objective of constraining UV extinction derived from the UV spectral-slope/infrared-excess correlation."

  2. THE KMOS{sup 3D} SURVEY: DESIGN, FIRST RESULTS, AND THE EVOLUTION OF GALAXY KINEMATICS FROM 0.7 ≤ z ≤ 2.7

    Energy Technology Data Exchange (ETDEWEB)

    Wisnioski, E.; Förster Schreiber, N. M.; Wuyts, S.; Wuyts, E.; Bandara, K.; Genzel, R.; Bender, R.; Davies, R.; Lang, P.; Mendel, J. T.; Beifiori, A.; Chan, J.; Fabricius, M.; Fudamoto, Y.; Kulkarni, S.; Kurk, J.; Lutz, D. [Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching (Germany); Wilman, D.; Fossati, M. [Universitäts-Sternwarte, Ludwig-Maximilians-Universität, Scheinerstrasse 1, D-81679 München (Germany); Brammer, G., E-mail: emily@mpe.mpg.de [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); and others

    2015-02-01

    We present the KMOS{sup 3D} survey, a new integral field survey of over 600 galaxies at 0.7 < z < 2.7 using KMOS at the Very Large Telescope. The KMOS{sup 3D} survey utilizes synergies with multi-wavelength ground- and space-based surveys to trace the evolution of spatially resolved kinematics and star formation from a homogeneous sample over 5 Gyr of cosmic history. Targets, drawn from a mass-selected parent sample from the 3D-HST survey, cover the star formation-stellar mass (M {sub *}) and rest-frame (U – V) – M {sub *} planes uniformly. We describe the selection of targets, the observations, and the data reduction. In the first-year of data we detect Hα emission in 191 M {sub *} = 3 × 10{sup 9}-7 × 10{sup 11} M {sub ☉} galaxies at z = 0.7-1.1 and z = 1.9-2.7. In the current sample 83% of the resolved galaxies are rotation dominated, determined from a continuous velocity gradient and v {sub rot}/σ{sub 0} > 1, implying that the star-forming ''main sequence'' is primarily composed of rotating galaxies at both redshift regimes. When considering additional stricter criteria, the Hα kinematic maps indicate that at least ∼70% of the resolved galaxies are disk-like systems. Our high-quality KMOS data confirm the elevated velocity dispersions reported in previous integral field spectroscopy studies at z ≳ 0.7. For rotation-dominated disks, the average intrinsic velocity dispersion decreases by a factor of two from 50 km s{sup –1}at z ∼ 2.3 to 25 km s{sup –1}at z ∼ 0.9. Combined with existing results spanning z ∼ 0-3, we show that disk velocity dispersions follow an evolution that is consistent with the dependence of velocity dispersion on gas fractions predicted by marginally stable disk theory.

  3. An Interacting Galaxy System along a Filament in a Void

    NARCIS (Netherlands)

    Beygu, B.; Kreckel, K.; van de Weijgaert, R.; van der Hulst, J. M.; van Gorkom, J. H.

    Cosmological voids provide a unique environment for the study of galaxy formation and evolution. The galaxy population in their interiors has properties significantly different from average field galaxies. As part of our Void Galaxy Survey (VGS), we have found a system of three interacting galaxies

  4. WINGS: WFIRST Infrared Nearby Galaxy Survey

    Science.gov (United States)

    Williams, Benjamin

    WFIRST's combination of wide field and high resolution will revolutionize the study of nearby galaxies. We propose to produce and analyze simulated WFIRST data of nearby galaxies and their halos to maximize the scientific yield in the limited observing time available, ensuring the legacy value of WFIRST's eventual archive. We will model both halo structure and resolved stellar populations to optimize WFIRST's constraints on both dark matter and galaxy formation models in the local universe. WFIRST can map galaxy structure down to ~35 mag/square arcsecond using individual stars. The resulting maps of stellar halos and accreting dwarf companions will provide stringent tests of galaxy formation and dark matter models on galactic (and even sub-galactic) scales, which is where the most theoretical tension exists with the Lambda-CDM model. With a careful, coordinated plan, WFIRST can be expected to improve current sample sizes by 2 orders of magnitude, down to surface brightness limits comparable to those currently reached only in the Local Group, and that are >4 magnitudes fainter than achievable from the ground due to limitations in star-galaxy separation. WFIRST's maps of galaxy halos will simultaneously produce photometry for billions of stars in the main bodies of galaxies within 10 Mpc. These data will transform studies of star formation histories that track stellar mass growth as a function of time and position within a galaxy. They also will constrain critical stellar evolution models of the near-infrared bright, rapidly evolving stars that can contribute significantly to the integrated light of galaxies in the near-infrared. Thus, with WFIRST we can derive the detailed evolution of individual galaxies, reconstruct the complete history of star formation in the nearby universe, and put crucial constraints on the theoretical models used to interpret near-infrared extragalactic observations. We propose a three-component work plan that will ensure these gains by

  5. Through the Looking GLASS: A JWST Exploration of Galaxy Formation and Evolution from Cosmic Dawn to Present Day

    Science.gov (United States)

    Treu, Tommaso; Abramson, L.; Bradac, M.; Brammer, G.; Fontana, A.; Henry, A.; Hoag, A.; Huang, K.; Mason, C.; Morishita, T.; Pentericci, L.; Wang, X.

    2017-11-01

    We propose a carefully designed set of observations of the lensing cluster Abell 2744 to study intrinsically faint magnified galaxies from the epoch of reionization to redshift of 1, demonstrating and characterizing complementary spectroscopic modes with NIRSPEC and NIRISS. The observations are designed to address the questions: 1) when did reionization happen and what were the sources of reionizing photons? 2) How do baryons cycle in and out of galaxies? This dataset with deep spectroscopy on the cluster and deep multiband NIRCAM imaging in parallel will enable a wealth of investigations and will thus be of interest to a broad section of the astronomical community. The dataset will illustrate the power and challenges of: 1) combining rest frame UV and optical NIRSPEC spectroscopy for galaxies at the epoch of reionization, 2) obtaining spatially resolved emission line maps with NIRISS, 3) combining NIRISS and NIRSPEC spectroscopy. Building on our extensive experience with HST slitless spectroscopy and imaging in clusters of galaxies as part of the GLASS, WISP, SURFSUP, and ASTRODEEP projects, we will provide the following science-enabling products to the community: 1)quantitative comparison of spatially resolved (NIRISS) and spectrally resolved (NIRSPEC) spectroscopy, 2) Object based interactive exploration tools for multi-instrument datasets, 3) Interface for easy forced extractionof slitless spectra based on coordinates, 4) UV-optical spectroscopic templates of highredshift galaxies, 5) NIRCAM parallel catalogs and a list of 26 z>=9 dropouts for spectroscopic follow-up in Cycle-2.

  6. Star Formation Histories of Nearby Dwarf Galaxies

    OpenAIRE

    Grebel, Eva K.

    2000-01-01

    Properties of nearby dwarf galaxies are briefly discussed. Dwarf galaxies vary widely in their star formation histories, the ages of their subpopulations, and in their enrichment history. Furthermore, many dwarf galaxies show evidence for spatial variations in their star formation history; often in the form of very extended old populations and radial gradients in age and metallicity. Determining factors in dwarf galaxy evolution appear to be both galaxy mass and environment. We may be observi...

  7. Star Clusters in Intermediate-Age Galaxy Merger Remnants

    Science.gov (United States)

    Miller, Bryan W.; Trancho, G.; Schweizer, F.

    2011-01-01

    Studies of globular cluster systems play a critical role in our understanding of galaxy formation. Star clusters are useful tracers of major star-formation events in galaxies since they are compact, relatively easy to detect, and have properties well described by simple-stellar-population models. Imaging with the Hubble Space Telescope has revealed that young compact star clusters are formed copiously during galaxy mergers, strengthening theories in which giant elliptical galaxies are formed through mergers of spirals. However, the formation and evolution of globular cluster systems is still not well understood. We should be able to observe how cluster systems evolve from the very young systems with power-law luminosity functions to old systems with log-normal luminosity functions like those observed in old elliptical galaxies. Finding intermediate-age cluster systems would constrain theories of cluster formation and destruction (evaporation, shocking, dynamical friction) as well as show the significance of merger events in the histories of galaxies. We present results of combining HST optical photometry with ground-based K-band photometry from NIRI and Flamingos-I on Gemini to study the star cluster systems of five intermediate-age merger remnants. The galaxies were chosen based on blue colors and fine structure such as shells and ripples that are indicative of past interactions. We find evidence for star clusters with ages consistent with the estimated merger ages. The properties of the star clusters systems and implications for galaxy and star cluster formation will be discussed. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada

  8. On the dynamics of supermassive black holes in gas-rich, star-forming galaxies: the case for nuclear star cluster co-evolution

    Science.gov (United States)

    Biernacki, Pawel; Teyssier, Romain; Bleuler, Andreas

    2017-07-01

    We introduce a new model for the formation and evolution of supermassive black holes (SMBHs) in the ramses code using sink particles, improving over previous work the treatment of gas accretion and dynamical evolution. This new model is tested against a suite of high-resolution simulations of an isolated, gas-rich, cooling halo. We study the effect of various feedback models on the SMBH growth and its dynamics within the galaxy. In runs without any feedback, the SMBH is trapped within a massive bulge and is therefore able to grow quickly, but only if the seed mass is chosen larger than the minimum Jeans mass resolved by the simulation. We demonstrate that, in the absence of supernovae (SN) feedback, the maximum SMBH mass is reached when active galactic nucleus (AGN) heating balances gas cooling in the nuclear region. When our efficient SN feedback is included, it completely prevents bulge formation, so that massive gas clumps can perturb the SMBH orbit, and reduce the accretion rate significantly. To overcome this issue, we propose an observationally motivated model for the joint evolution of the SMBH and a parent nuclear star cluster (NSC), which allows the SMBH to remain in the nuclear region, grow fast and resist external perturbations. In this scenario, however, SN feedback controls the gas supply and the maximum SMBH mass now depends on the balance between AGN heating and gravity. We conclude that SMBH/NSC co-evolution is crucial for the growth of SMBH in high-z galaxies, the progenitors of massive ellipticals today.

  9. The evolution of novel host use is unlikely to be constrained by trade-offs or a lack of genetic variation.

    Science.gov (United States)

    Gompert, Zachariah; Jahner, Joshua P; Scholl, Cynthia F; Wilson, Joseph S; Lucas, Lauren K; Soria-Carrasco, Victor; Fordyce, James A; Nice, Chris C; Buerkle, C Alex; Forister, Matthew L

    2015-06-01

    The genetic and ecological factors that shape the evolution of animal diets remain poorly understood. For herbivorous insects, the expectation has been that trade-offs exist, such that adaptation to one host plant reduces performance on other potential hosts. We investigated the genetic architecture of alternative host use by rearing individual Lycaeides melissa butterflies from two wild populations in a crossed design on two hosts (one native and one introduced) and analysing the genetic basis of differences in performance using genomic approaches. Survival during the experiment was highest when butterfly larvae were reared on their natal host plant, consistent with local adaptation. However, cross-host correlations in performance among families (within populations) were not different from zero. We found that L. melissa populations possess genetic variation for larval performance and variation in performance had a polygenic basis. We documented very few genetic variants with trade-offs that would inherently constrain diet breadth by preventing the optimization of performance across hosts. Instead, most genetic variants that affected performance on one host had little to no effect on the other host. In total, these results suggest that genetic trade-offs are not the primary cause of dietary specialization in L. melissa butterflies. © 2015 John Wiley & Sons Ltd.

  10. Xray cavities in a sample of 83 SPT-selected clusters galaxies. Tracing the evolution of AGN feedback in clusters of galaxies out to z=1.2

    Energy Technology Data Exchange (ETDEWEB)

    Hlavacek-Larrondo, J.; McDonald, M.; Benson, B. A.; Forman, W. R.; Allen, S. W.; Bleem, L. E.; Ashby, M. L. N.; Bocquet, S.; Brodwin, M.; Dietrich, J. P.; Jones, C.; Liu, J.; Reichardt, C. L.; Saliwanchik, B. R.; Saro, A.; Schrabback, T.; Song, J.; Stalder, B.; Vikhlinin, A.; Zenteno, A.

    2015-05-18

    X-ray cavities are key tracers of mechanical (or radio mode) heating arising from the active galactic nuclei (AGNs) in brightest cluster galaxies (BCGs). We report on a survey for X-ray cavities in 83 massive, high-redshift ($0.4\\lt z\\lt 1.2$) clusters of galaxies selected by their Sunyaev-Zel’dovich signature in the South Pole Telescope data. Based on Chandra X-ray images, we find a total of six clusters having symmetric pairs of surface brightness depressions consistent with the picture of radio jets inflating X-ray cavities in the intracluster medium (ICM). The majority of these detections are of relatively low significance and require deeper follow-up data in order to be confirmed. Further, this search will miss small (<10 kpc) X-ray cavities that are unresolved by Chandra at high ($z\\gtrsim 0.5$) redshift. Despite these limitations, our results suggest that the power generated by AGN feedback in BCGs has remained unchanged for over half of the age of the universe ($\\gt 7$ Gyr at $z\\sim 0.8$). On average, the detected X-ray cavities have powers of $(0.8-5)\\times {{10}^{45}}\\ {\\rm erg}\\ {{{\\rm s}}^{-1}}$, enthalpies of $(3-6)\\times {{10}^{59}}\\ {\\rm erg}$, and radii of ~17 kpc. Integrating over 7 Gyr, we find that the supermassive black holes in BCGs may have accreted 10(8) to several ${{10}^{9}}\\,{{M}_{\\odot }}$ of material to power these outflows. This level of accretion indicates that significant supermassive black hole growth may occur not only at early times, in the quasar era, but at late times as well. We also find that X-ray cavities at high redshift may inject an excess heat of 0.1–1.0 keV per particle into the hot ICM above and beyond the energy needed to offset cooling. Although this result needs to be confirmed, we note that the magnitude of excess heating is similar to the energy needed to preheat clusters, break self-similarity, and explain the excess entropy in hot atmospheres.

  11. Probing Evolution And Reionization Spectroscopically {PEARS}

    Science.gov (United States)

    Malhotra, Sangeeta

    2005-07-01

    While imaging with HST has gone deep enough to probe the highest redshifts, e.g. the GOODS survey and the Ultra Deep Field, spectroscopic identifications have not kept up. We propose an ACS grism survey to get slitless spectra of all sources in a wide survey region {8 ACS fields} up to z =27.0 magnitude, and an ultradeep field in the HUDF reaching sources up to z =28 magnitude. The PEARS survey will: {1} Find and spectrocopically confirm all galaxies between z=4-7. {2} Probe the reionization epoch by robustly determining the luminosity function of galaxies and low luminosity AGNs at z = 4 - 6. With known redshifts, we can get a local measure of star formation and ionization rate in case reionization is inhomogeneous. {3} Study galaxy formation and evolution by finding galaxies in a contiguous redshift range between 4 < z < 7, and black hole evolution through a census of low-luminosity AGNs. {4} Get a robust census of galaxies with old stellar populations at 1 < z < 2.5, invaluable for checking consistency with heirarchical models of galaxy formation. Fitting these galaxies' spectra will yield age and metallicity estimates. {5} Study star-formation and galaxy assembly at its peak at 1< z < 2 by identifying emission lines in star-forming galaxies, old populations showing the 4000A break, and any combination of the two. {6} Constrain faint white dwarfs in the Galactic halo and thus measure their contribution to the dark matter halo. {7} Derive spectro-photometric redshifts by using the grism spectra along with broadband data. This will be the deepest unbiased spectroscopy yet, and will enhance the value of the multiwavelength data in UDF and the GOODS fields to the astronomical community. To this end we will deliver reduced spectra to the HST archives.

  12. The number density of quiescent compact galaxies at intermediate redshift

    Energy Technology Data Exchange (ETDEWEB)

    Damjanov, Ivana [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hwang, Ho Seong; Geller, Margaret J.; Chilingarian, Igor, E-mail: idamjanov@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)

    2014-09-20

    Massive compact systems at 0.2 < z < 0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ∼200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z ∼ 0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2 < z < 0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0 < z < 2.

  13. High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T. J. L.; Hill, V.; Tolstoy, E.; Irwin, M. J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Martins, F.; Bournaud, F.; Monier, R.; Reylé, C.

    2014-01-01

    From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf spheroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between --2.0 and

  14. High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T.J.L.; Hill, V.; Tolstoy, E.; Irwin, M.J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Bournaud, F.; Martins, F.; Monier, R.; Reyle, C.

    2014-01-01

    From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf speroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between -2.0 and -

  15. How Environment Affects Star Formation: Tracing Activity in High Redshift Galaxy Clusters

    Science.gov (United States)

    Alberts, Stacey; Pope, A.; Brodwin, M.; Atlee, D. W.; Lin, Y.; Chary, R.; Dey, A.; Eisenhardt, P. R.; Gettings, D.; Gonzalez, A. H.; Jannuzi, B.; Mancone, C.; Moustakas, J.; Snyder, G. F.; Stanford, S. A.; Stern, D.; Weiner, B. J.; Zeimann, G.

    2014-01-01

    The emerging picture of the evolution of cluster galaxies indicates that the epoch of z>1 is a crucial period of active star formation and mass assembly in clusters. In this dissertation, I leverage a uniformly-selected cluster sample from the IRAC Shallow Cluster Survey (ISCS) with Herschel imaging to analyse the star formation (SF) activity in cluster galaxies over the past ten billion years. This analysis is two-fold: 1) using 274 clusters across the 9 square degree Bootes field, I perform a stacking analysis of mass-limited samples of cluster and field galaxies using wide-field Herschel observations over a long redshift baseline, z=0.3-1.5. I find that the average SF activity in cluster galaxies is evolving faster than in the field, with field-like SF in the cluster cores and enhanced SF activity in the cluster outskirts at z>1.2. By further breaking down my analysis by galaxy mass and type, I determine which mechanisms are capable of driving this evolution. 2) I use unique, deep Herschel imaging of 11 spectroscopically-confirmed clusters from z=1.1-1.8 to study the properties of individual infrared bright cluster galaxies as a function of redshift and cluster-centric radius. Combined with ancillary data, I determine the star formation, dust, and AGN properties of the most active cluster galaxies and tie the evolution of these properties back to the environment by comparing to field populations. By combining these two approaches, I constrain cluster galaxy properties during a pivotal epoch of dust-obscured star formation activity and mass assembly in some of the most extreme structures in the Universe.

  16. Escaping Lyman Continuum in Strongly Lensed Galaxies at z=2.0-2.5

    Science.gov (United States)

    Fan, Xiaohui

    2013-10-01

    We propose to obtain deep WFC3 UVIS channel near ultraviolet {NUV} images of a sample of 6 bright lensed galaxies at z = 2.0 - 2.5 to detect the escaping Lyman continuum {LyC} radiation in order to study the physical properties of the LyC emitting region and the evolution of ionizing photon escape fraction with redshift. The LyC escape fraction is a key parameter in determining the contribution of star-forming galaxies to UV ionization background and to the cosmic reionization. It is, however, poorly constrained with conflicting results. In this proposal, we will use the observations of the brightest lensed galaxies {r<21.0} to provide accurate measurement of escape fraction in high-redshift galaxies, sensitive to the flux ratio between intergalactic medium corrected LyC and 1500A of as low as 0.5-3% in individual galaxies, and 0.2% when stacking all galaxies. In addition, lensing effect will allow us to probe a wide range of intrinsic luminosity {-20.5galaxies provided by existing deep HST imaging and ground-based near-IR spectroscopy to constrain physical models of LyC escape mechanism. Our sample will also fill the gap of the redshift range between 2.0 - 2.5 that has not been probed in previous works, allowing study of the evolution of escape fraction in the redshift range of z = 1 to 3.5.

  17. UGC 7639: A Dwarf Galaxy in the Canes Venatici I Cloud

    Directory of Open Access Journals (Sweden)

    L. M. Buson

    2015-01-01

    Full Text Available We want to get insight into the formation mechanism and the evolution of UGC 7639, a dwarf galaxy in the Canes Venatici I Cloud (CVnIC. We used archival multiwavelength data to constrain its global properties. Ultraviolet images show that UGC 7639 inner regions are composed mostly by young stellar populations. In addition, we used smoothed particle hydrodynamics simulations with chemophotometric implementation to account for its formation and evolution. UGC 7639 is an example of blue dwarf galaxy whose global properties are well matched by our multiwavelength approach, that is, a suitable approach to highlight the evolution also of these galaxies as a class. We found that the global properties of UGC 7639, namely, its total absolute B-band magnitude, its whole spectral energy distribution, and morphology, are well matched by an encounter with a system four times more massive than our target. Moreover, the current star formation rate of the simulated dwarf, ≈0.03 M⊙ yr−1, is in good agreement with our UV-based estimate. We derived a galaxy age of 8.6 Gyr. Following our simulation, the ongoing star formation will extinguish within 1.6 Gyr, thus leaving a red dwarf galaxy.

  18. Lithospheric rheological heterogeneity across an intraplate rift basin (Linfen Basin, North China) constrained from magnetotelluric data: Implications for seismicity and rift evolution

    Science.gov (United States)

    Yin, Yaotian; Jin, Sheng; Wei, Wenbo; Ye, Gaofeng; Jing, Jian'en; Zhang, Letian; Dong, Hao; Xie, Chengliang; Liang, Hongda

    2017-10-01

    We take the Linfen Basin, which is the most active segment of the Cenozoic intraplate Shanxi Rift, as an example, showing how to use magnetotelluric data to constrain lithospheric rheological heterogeneities of intraplate tectonic zones. Electrical resistivity models, combined with previous rheological numerical simulation, show a good correlation between resistivity and rheological strength, indicating the mechanisms of enhanced conductivity could also be reasons of reduced viscosity. The crust beneath the Linfen Basin shows overall stratified features in both electrical resistivity and rheology. The uppermost crustal conductive layer is dominated by friction sliding-type brittle fracturing. The high-resistivity mid-crust is inferred to be high-viscosity metamorphic basement being intersected by deep fault. The plastic lower crust show significantly high-conductivity feature. Seismicity appears to be controlled by crustal rheological heterogeneity. Micro-earthquakes mainly distribute at the brittle-ductile transition zones as indicated by high- to low-resistivity interfaces or the high pore pressure fault zones while the epicenters of two giant destructive historical earthquakes occur within the high-resistivity and therefore high-strength blocks near the inferred rheological interfaces. The lithosphere-scale lateral rheological heterogeneity along the profile can also be illustrated. The crust and upper mantle beneath the Ordos Block, Lüliang Mountains and Taihang Mountains are of high rheological strength as indicated by large-scale high-resistivity zones while a significant high-conductivity, lithosphere-scale weak zone exists beneath the eastern margin of the Linfen Basin. According to previous geodynamic modeling works, we suggest that this kind of lateral rheological heterogeneity may play an essential role for providing driving force for the formation and evolution of the Shanxi Rift, regional lithospheric deformation and earthquake activities under the

  19. Tectono-thermal evolution of the southwestern Alxa Tectonic Belt, NW China: Constrained by apatite U-Pb and fission track thermochronology

    Science.gov (United States)

    Song, Dongfang; Glorie, Stijn; Xiao, Wenjiao; Collins, Alan S.; Gillespie, Jack; Jepson, Gilby; Li, Yongchen

    2018-01-01

    The Central Asian Orogenic Belt (CAOB) is regarded to have undergone multiple phases of intracontinental deformation during the Meso-Cenozoic. Located in a key position along the southern CAOB, the Alxa Tectonic Belt (ATB) connects the northernmost Tibetan Plateau with the Mongolian Plateau. In this paper we apply apatite U-Pb and fission track thermochronological studies on varieties of samples from the southwestern ATB, in order to constrain its thermal evolution. Precambrian bedrock samples yield late Ordovician-early Silurian ( 430-450 Ma) and late Permian ( 257 Ma) apatite U-Pb ages; the late Paleozoic magmatic-sedimentary samples yield relatively consistent early Permian ages from 276 to 290 Ma. These data reveal that the ATB experienced multiple Paleozoic tectono-thermal events, as the samples passed through the apatite U-Pb closure temperature ( 350-550 °C). We interpret these tectonic events to record the long-lived subduction-accretion processes of the Paleo-Asian Ocean during the formation of the southern CAOB, with possible thermal influence of the Permian Tarim mantle plume. Apatite fission track (AFT) data and thermal history modelling reveal discrete low-temperature thermal events for the ATB, inducing cooling/reheating through the AFT partial annealing zone ( 120-60 °C). During the Permian, the samples underwent rapid cooling via exhumation or denudation from deep crustal levels to temperatures slab break-off. These results indicate that the ATB may have been stable after late Cretaceous in contrast to the Qilian Shan and Tianshan. Finally, our results indicate differential exhumation scenario occurred across the southwestern ATB during the Cretaceous.

  20. Spiral galaxy HI models, rotation curves and kinematic classifications

    Science.gov (United States)

    Wiegert, Theresa B. V.

    Although galaxy interactions cause dramatic changes, galaxies also continue to form stars and evolve when they are isolated. The dark matter (DM) halo may influence this evolution since it generates the rotational behaviour of galactic disks which could affect local conditions in the gas. Therefore we study neutral hydrogen kinematics of non-interacting, nearby spiral galaxies, characterising their rotation curves (RC) which probe the DM halo; delineating kinematic classes of galaxies; and investigating relations between these classes and galaxy properties such as disk size and star formation rate (SFR). To generate the RCs, we use GalAPAGOS (by J. Fiege). My role was to test and help drive the development of this software, which employs a powerful genetic algorithm, constraining 23 parameters while using the full 3D data cube as input. The RC is here simply described by a tanh-based function which adequately traces the global RC behaviour. Extensive testing on artificial galaxies show that the kinematic properties of galaxies with inclination >40 degrees, including edge-on galaxies, are found reliably. Using a hierarchical clustering algorithm on parametrised RCs from 79 galaxies culled from literature generates a preliminary scheme consisting of five classes. These are based on three parameters: maximum rotational velocity, turnover radius and outer slope of the RC. To assess the relationship between DM content and the kinematic classes, we generate mass models for 10 galaxies from the THINGS and WHISP surveys, and J. Irwin's sample. In most cases mass models using GalAPAGOS RCs were similar to those using traditional "tilted-ring'' method RCs. The kinematic classes are mainly distinguished by their rotational velocity. We confirm correlations between increasing velocity and B-magnitude, optical disk size, and find earlier type galaxies among the strong rotators. SFR also increases with maximum rotational velocity. Given our limited subsample, we cannot discern a

  1. Cosmological Constraints from the Redshift Dependence of the Volume Effect Using the Galaxy 2-point Correlation Function across the Line of Sight

    Science.gov (United States)

    Li, Xiao-Dong; Park, Changbom; Sabiu, Cristiano G.; Park, Hyunbae; Cheng, Cheng; Kim, Juhan; Hong, Sungwook E.

    2017-08-01

    We develop a methodology to use the redshift dependence of the galaxy 2-point correlation function (2pCF) across the line of sight, ξ ({r}\\perp ), as a probe of cosmological parameters. The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. This geometrical distortion can be observed as a redshift-dependent rescaling in the measured ξ ({r}\\perp ). We test this methodology using a sample of 1.75 billion mock galaxies at redshifts 0, 0.5, 1, 1.5, and 2, drawn from the Horizon Run 4 N-body simulation. The shape of ξ ({r}\\perp ) can exhibit a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. Other contributions, including the gravitational growth of structure, galaxy bias, and the redshift space distortions, do not produce large redshift evolution in the shape. We show that one can make use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This method could be applicable to future large-scale structure surveys, especially photometric surveys such as DES and LSST, to derive tight cosmological constraints. This work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities.

  2. Modelling the gas kinematics of an atypical Ly α emitting compact dwarf galaxy

    Science.gov (United States)

    Forero-Romero, Jaime E.; Gronke, Max; Remolina-Gutiérrez, Maria Camila; Garavito-Camargo, Nicolás; Dijkstra, Mark

    2018-02-01

    Star-forming compact dwarf galaxies (CDGs) resemble the expected pristine conditions of the first galaxies in the Universe and are the best systems to test models on primordial galaxy formation and evolution. Here, we report on one of such CDGs, Tololo 1214-277, which presents a broad, single peaked, highly symmetric Ly α emission line that had evaded theoretical interpretation so far. In this paper, we reproduce for the first time these line features with two different physically motivated kinematic models: an interstellar medium composed by outflowing clumps with random motions and an homogeneous gaseous sphere undergoing solid body rotation. The multiphase model requires a clump velocity dispersion of 54.3 ± 0.6 km s-1 with outflows of 54.3 ± 5.1 km s-1 , while the bulk rotation velocity is constrained to be 348^{+75}_{-48} km s-1. We argue that the results from the multiphase model provide a correct interpretation of the data. In that case, the clump velocity dispersion implies a dynamical mass of 2 × 109 M⊙, 10 times its baryonic mass. If future kinematic maps of Tololo 1214-277 confirm the velocities suggested by the multiphase model, it would provide additional support to expect such kinematic state in primordial galaxies, opening the opportunity to use the models and methods presented in this paper to constrain the physics of star formation and feedback in the early generation of Ly α -emitting galaxies.

  3. The dwarf galaxy population of nearby galaxy clusters

    NARCIS (Netherlands)

    Lisker, Thorsten; Wittmann, Carolin; Pak, Mina; Janz, Joachim; Bialas, Daniel; Peletier, Reynier; Grebel, Eva; Falcon Barroso, Jesus; Toloba, Elisa; Smakced Collaboration, Focus Collaboration

    The Fornax, Virgo, Ursa Major and Perseus galaxy clusters all have very different characteristics, in terms of their density, mass, and large-scale environment. We can regard these clusters as laboratories for studying environmental influence on galaxy evolution, using the sensitive low-mass

  4. Dwarf elliptical galaxies

    Science.gov (United States)

    Ferguson, Henry C.; Binggeli, Bruno

    1994-01-01

    Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than M(sub B) = -16, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how well currently availiable data can constrain (a) models for the formation of dE's, (b) the physical and evolutionary connections between different types of galaxies that overlap in the same portion of the mass-spectrum of galaxies, (c) the contribution of dE's to the galaxy luminosity functions in clusters and the field, (d) the star-forming histories of dE's and their possible contribution to faint galaxy counts, and (e) the clustering properties of dE's. In addressing these issues, we highlight the extent to which selection effects temper these constraints, and outline areas where new data would be particularly valuable.

  5. Massive Black Hole Binaries: Dynamical Evolution and Observational Signatures

    Directory of Open Access Journals (Sweden)

    M. Dotti

    2012-01-01

    Full Text Available The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here, we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries and of the candidates discussed in literature to date.

  6. GREEN GALAXIES IN THE COSMOS FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Zhizheng; Kong, Xu; Fan, Lulu, E-mail: panzz@mail.ustc.edu.cn, E-mail: xkong@ustc.edu.cn [Center of Astrophysics, University of Science and Technology of China, Hefei 230026 (China)

    2013-10-10

    We present research on the morphologies, spectra, and environments of ≈2350 'green valley' galaxies at 0.2 < z < 1.0 in the COSMOS field. The bimodality of dust-corrected NUV–r {sup +} color is used to define 'green valley'; it removes dusty star-forming galaxies from galaxies that are truly transitioning between the blue cloud and the red sequence. Morphological parameters of green galaxies are intermediate between those of blue and red galaxy populations, both on the Gini-asymmetry and the Gini-M{sub 20} planes. Approximately 60%-70% of green disk galaxies have intermediate or big bulges, and only 5%-10% are pure disk systems, based on morphological classification using the Zurich Estimator of Structural Types. The obtained average spectra of green galaxies are intermediate between blue and red ones in terms of [O II], Hα, and Hβ emission lines. Stellar population synthesis on the average spectra shows that green galaxies are on average older than blue galaxies but younger than red galaxies. Green galaxies and blue galaxies have similar projected galaxy density (Σ{sub 10}) distributions at z > 0.7. At z < 0.7, the fractions of M{sub *} < 10{sup 10.0} M{sub ☉} green galaxies located in a dense environment are found to be significantly larger than those of blue galaxies. The morphological and spectral properties of green galaxies are consistent with the transitioning population between the blue cloud and the red sequence. The possible mechanisms for quenching star formation activities in green galaxies are discussed. The importance of active galactic nucleus feedback cannot be well constrained in our study. Finally, our findings suggest that environmental conditions, most likely starvation and harassment, significantly affect the transformation of M{sub *} < 10{sup 10.0} M{sub ☉} blue galaxies into red galaxies, especially at z < 0.5.

  7. The Metallicity of Void Dwarf Galaxies

    NARCIS (Netherlands)

    Kreckel, K.; Croxall, K.; Groves, B.; van de Weygaert, R.; Pogge, R. W.

    The current ΛCDM cosmological model predicts that galaxy evolution proceeds more slowly in lower density environments, suggesting that voids are a prime location to search for relatively pristine galaxies that are representative of the building blocks of early massive galaxies. To test the

  8. Optical galaxy cluster detection across a wide redshift range

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Jiangang [Univ. of Michigan, Ann Arbor, MI (United States)

    2009-04-01

    The past decade is one of the most exciting period in the history of physics and astronomy. The discovery of cosmic acceleration dramatically changed our understanding about the evolution and constituents of the Universe. To accommodate the new acceleration phase into our well established Big Bang cosmological scenario under the frame work of General Relativity, there must exist a very special substance that has negative pressure and make up about 73% of the total energy density in our Universe. It is called Dark Energy. For the first time people realized that the vast majority of our Universe is made of things that are totally different from the things we are made of. Therefore, one of the major endeavors in physics and astronomy in the coming years is trying to understand, if we can, the nature of dark energy. Understanding dark energy cannot be achieved from pure logic. We need empirical evidence to finally determine about what is dark energy. The better we can constrain the energy density and evolution of the dark energy, the closer we will get to the answer. There are many ways to constrain the energy density and evolution of dark energy, each of which leads to degeneracy in certain directions in the parameter space. Therefore, a combination of complimentary methods will help to reduce the degeneracies and give tighter constraints. Dark energy became dominate over matter in the Universe only very recently (at about z ~ 1.5) and will affect both the cosmological geometry and large scale structure formation. Among the various experiments, some of them constrain the dark energy mainly via geometry (such as CMB, Supernovae) while some others provides constraints from both structures and geometry (such as BAO, Galaxy Clusters) Galaxy clusters can be used as a sensitive probe for cosmology. A large cluster catalog that extends to high redshift with well measured masses is indispensable for precisely constraining cosmological parameters. Detecting clusters in optical

  9. Inside-out growth or inside-out quenching? Clues from colour gradients of local galaxies

    Science.gov (United States)

    Lian, Jianhui; Yan, Renbin; Blanton, Michael; Kong, Xu

    2017-12-01

    We constrain the spatial gradient of star formation history (SFH) within galaxies using the colour gradients in NUV - u (where NUV stands for near-ultraviolet) and u - i for a local spatially resolved galaxy sample. By splitting each galaxy into an inner and an outer part, we find that most galaxies show negative gradients in these two colours. We first rule out dust extinction gradient and metallicity gradient as the dominant source for the colour gradient. Then using stellar population models, we explore variations in SFH to explain the colour gradients. As shown by our earlier work, a two-phase SFH consisting of an early secular evolution (growth) phase and a subsequent rapid evolution (quenching) phase is necessary to explain the observed colour distributions among galaxies. We explore two different inside-out growth models and two different inside-out quenching models by varying parameters of the SFH between inner and outer regions of galaxies. Two of the models can explain the observed range of colour gradients in NUV - u and u - i colours. We further distinguish them using an additional constraint provided by the u - i colour gradient distribution, under the assumption of constant galaxy formation rate and a common SFH followed by most galaxies. We find the best model is an inside-out growth model in which the inner region has a shorter e-folding time-scale in the growth phase than the outer region. More spatially resolved UV observations are needed to improve the significance of the result.

  10. The Co-Evolution of Star Formation and Powerful Radio Activity in Galaxies During Radio-Mode Feedback

    Science.gov (United States)

    O'Dea, Christopher

    2017-08-01

    Feedback from radio sources is thought to be a key ingredient in determining the shape of the galaxy luminosity function. Compact Steep Spectrum (CSS) radio sources are galactic scale (1-20 kpc) and so probe radio source feedback to the host galaxy. We propose to carry out WFC3 UV imaging of the line-free continuum between [CIII] 1909 and MgII 2798, as well as WFC3 line-free optical continuum imaging, in nine CSS radio sources. Following our pilot study that detected spatially extended UV radiation in 3/3 CSS sources, we propose observations which will increase our total sample size by a factor of 4. Imaging the UV continuum from hot massive stars is the best way to study recently triggered and ongoing star formation. We will map in detail the star formation regions in relation to the radio structures and multiwavelength properties of the sources. The high spatial resolution will allow us to separate morphologically and characterize the generic star formation which is due to gas infall, and that which is due to triggering by the radio source.

  11. The Compton-thick Growth of Supermassive Black Holes constrained

    Science.gov (United States)

    Buchner, Johannes; Georgakakis, Antonis; Nandra, Kirpal; Brightman, Murray; Menzel, Marie-Luise; Liu, Zhu; Hsu, Li-Ting; Salvato, Mara; Rangel, Cyprian; Aird, James

    2017-08-01

    A heavily obscured growth phase of supermassive black holes (SMBH) is thought to be important in the co-evolution with galaxies. X-rays provide a clean and efficient selection of unobscured and obscured AGN. Recent work with deeper observations and improved analysis methodology allowed us to extend constraints to Compton-thick number densities. We present the first luminosity function of Compton-thick AGN at z=0.5-4 and constrain the overall mass density locked into black holes over cosmic time, a fundamental constraint for cosmological simulations. Recent studies including ours find that the obscuration is redshift and luminosity-dependent in a complex way, which rules out entire sets of obscurer models. A new paradigm, the radiation-lifted torus model, is proposed, in which the obscurer is Eddington-rate dependent and accretion creates and displaces torus clouds. We place observational limits on the behaviour of this mechanism.

  12. The host galaxy and environment of a bright QSO at z=7.54

    Science.gov (United States)

    Banados, Eduardo

    2017-08-01

    After almost a decade of intense search, our team has finally discovered a bright QSO well within the epoch of reionization, at z=7.54. This is by far the most distant QSO known (previous record: 7.08), at a cosmic age of 690 Myr, i.e., only 5% of our universe's current age. This is the first QSO whose spectrum shows clear evidence of an intergalactic medium that is >10% neutral and that reionization is underway. We propose deep HST ACS and WFC/IR imaging of this unique source with two main goals. (i) Unveil the rest-frame UV stellar light from the host galaxy to directly probe supermassive black hole/galaxy co-evolution at the highest accessible redshift. (ii) Search for galaxies physically associated with the QSO and test whether this object resides in one of the densest and most biased environment at the peak of the reionization epoch. HST observations are indispensable to address these topics for two reasons: (a) only HST provides the spatial resolution to separate the central bright light source from the underlying host galaxy and (b) at this record-redshift, only space-based imaging can provide the depths necessary to constrain the environment. These HST observations will provide key insights into the formation and evolution of the first super massive black holes, galaxies, and large-scale structure of the universe.

  13. Extinction Mapping and Dust-to-Gas Ratios of Nearby Galaxies using LEGUS

    Science.gov (United States)

    Kahre, Lauren; Walterbos, Rene; Kim, Hwihyun; Thilker, David; Lee, Janice; LEGUS Team

    2018-01-01

    Dust is commonly used as a tracer for cold dense gas, either through IR and NIR emission maps or through extinction mapping, and dust abundance and gas metallicity are critical constraints for chemical and galaxy evolution models. Extinction mapping has been used to trace dust column densities in the Milky Way, the Magellanic Clouds, and M31. The maps for M31 use IR and NIR photometry of red giant branch stars, which is more difficult to obtain for more distant galaxies. Work by Kahre et al. (in prep) uses the extinctions derived for individual massive stars using the isochrone-matching method described by Kim et al. (2012) to generate extinction maps for these more distant galaxies.Isochrones of massive stars lie in the same location on a color-color diagram with little dependence on metallicity and luminosity class, so the extinction can be directly derived from the observed photometry. We generate extinction maps using photometry of massive stars from the Hubble Space Telescope for several of the nearly 50 galaxies observed by the Legacy Extragalactic Ultraviolet Survey (LEGUS). The derived extinction maps will allow us to correct ground-based and HST Halpha maps for extinction, and will be used to constrain changes in the dust-to-gas ratio across the galaxy sample and in different star formation, metallicity and morphological environments. Previous studies have found links between galaxy metallicity and the dust-to-gas mass ratio. We present a study of LEGUS galaxies spanning a range of distances, metallicities, and galaxy morphologies, expanding on our previous study of metal-poor dwarfs Holmberg I and II and giant spirals NGC 6503 and NGC 628. We see clear evidence for changes in the dust-to-gas mass ratio with changing metallicity. We also examine changes in the dust-to-gas mass ratio with galactocentric radius. Ultimately, we will provide constraints on the dust-to-gas mass ratio across a wide range of galaxy environments.

  14. THE MAJOR AND MINOR GALAXY MERGER RATES AT z < 1.5

    Energy Technology Data Exchange (ETDEWEB)

    Lotz, Jennifer M. [National Optical Astronomical Observatories, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Jonsson, Patrik [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Cox, T. J. [Carnegie Observatories, Pasadena, CA (United States); Croton, Darren [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn (Australia); Primack, Joel R. [Department of Physics, University of California, Santa Cruz, CA (United States); Somerville, Rachel S. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Stewart, Kyle, E-mail: lotz@stsci.edu [Jet Propulsion Laboratory, Pasadena, CA (United States)

    2011-12-01

    Calculating the galaxy merger rate requires both a census of galaxies identified as merger candidates and a cosmologically averaged 'observability' timescale (T{sub obs}(z)) for identifying galaxy mergers. While many have counted galaxy mergers using a variety of techniques, (T{sub obs}(z)) for these techniques have been poorly constrained. We address this problem by calibrating three merger rate estimators with a suite of hydrodynamic merger simulations and three galaxy formation models. We estimate (T{sub obs}(z)) for (1) close galaxy pairs with a range of projected separations, (2) the morphology indicator G - M{sub 20}, and (3) the morphology indicator asymmetry A. Then, we apply these timescales to the observed merger fractions at z < 1.5 from the recent literature. When our physically motivated timescales are adopted, the observed galaxy merger rates become largely consistent. The remaining differences between the galaxy merger rates are explained by the differences in the ranges of the mass ratio measured by different techniques and differing parent galaxy selection. The major merger rate per unit comoving volume for samples selected with constant number density evolves much more strongly with redshift ({proportional_to}(1 + z){sup +3.0{+-}1.1}) than samples selected with constant stellar mass or passively evolving luminosity ({proportional_to}(1 + z){sup +0.1{+-}0.4}). We calculate the minor merger rate (1:4 evolution with redshift.

  15. The Spitzer/Swift Gamma-Ray Burst Host Galaxy Legacy Survey

    Science.gov (United States)

    Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Milvang-Jensen, Bo; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna; Watson, Darach

    2016-08-01

    Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample - providing the definitive resource with which to examine all aspects of the GRB/galaxy connection for years to come and setting the stage for intensive JWST follow-up of the most interesting sources from our sample.

  16. A Century of Galaxy Spectroscopy

    Science.gov (United States)

    Rubin, Vera C.

    1995-10-01

    The first successful spectrum of a galaxy, M31, was obtained in 1898 and published in a two-page paper in the young Astrophysical Journal (Scheiner 1899). Thus the first century of galaxy spectroscopy and the first century of the Astrophysical Journal are almost coincident; I celebrate both in this paper. I describe the very early history of the determination of internal kinematics in spiral galaxies, often by quoting the astronomers' own published words. By mid-century, observations with improved optical and radio telescopes offered evidence that much of the matter in a galaxy is dark. As the century ends, research interests have enlarged to include study of spheroidal and disk galaxies with complex nuclear (and other) kinematics. These complicated velocity patterns are understood as the result of interactions, acquisitions, and mergers, and offer clear evidence of the important role of gravitational effects in galaxy evolution.

  17. Galaxies in the Early Universe

    DEFF Research Database (Denmark)

    Krogager, Jens-Kristian

    in Chapter 3 is found to be a young, star-forming galaxy with evidence for strong outflows of gas. This suggests that the more evolved and metal-rich DLAs overlap with the faint end of the luminosity selected galaxies in terms of mass, metallicity, star formation rate, and age. DLAs are generally observed......Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our...... analyses are biased towards the brightest galaxies at all times (as these are easier to observe and identify). A complementary method relies on the absorption imprint from neutral gas in galaxies, the so-called damped Ly absorbers (DLAs) seen towards distant bright objects. This thesis seeks to understand...

  18. Nature vs. nurture in the low-density environment: structure and evolution of early-type dwarf galaxies in poor groups

    Science.gov (United States)

    Annibali, F.; Grützbauch, R.; Rampazzo, R.; Bressan, A.; Zeilinger, W. W.

    2011-04-01

    We present the stellar population properties of 13 dwarf galaxies residing in poor groups (low-density environment, LDE) observed with VIMOS at VLT. Ages, metallicities, and [α/Fe] ratios were derived within an r < re/2 aperture from the Lick indices Hβ, Mgb, Fe5270, and Fe5335 through comparison with our simple stellar population (SSP) models that account for variable [α/Fe] ratios. For a fiducial subsample of 10 early-type dwarfs, we derived median values and scatters around the medians of 5.7 ± 4.4 Gyr, -0.26 ± 0.28, and -0.04 ± 0.33 for age, log Z/Z⊙, and [α/Fe] , respectively. For a selection of bright early-type galaxies (ETGs) from an earlier sample residing in a comparable environment, we derive median values of 9.8 ± 4.1 Gyr, 0.06 ± 0.16, and 0.18 ± 0.13 for the same stellar population parameters. It follows that dwarfs are on average younger, less metal rich, and less enhanced in the α-elements than giants, in agreement with the extrapolation to the low-mass regime of the scaling relations derived for giant ETGs. From the total (dwarf + giant) sample, we find that age ∝ σ0.39 ± 0.22, Z ∝ σ0.80 ± 0.16, and α/Fe ∝ σ0.42 ± 0.22. We also find correlations with morphology, in the sense that the metallicity and the [α/Fe] ratio increase with the Sersic index n or with the bulge-to-total light fraction B/T. The presence of a strong morphology-[α/Fe] relation appears to contradict the possible evolution along the Hubble sequence from low B/T (low n) to high B/T (high n) galaxies. We also investigate the role played by environment by comparing the properties of our LDE dwarfs with those of Coma red passive dwarfs from the literature. We find possible evidence that LDE dwarfs experienced more prolonged star formations than Coma dwarfs, however larger data samples are needed to draw firmer conclusions. Based on observations obtained at the European Southern Observatory, La Silla, Chile.

  19. The brightest galaxies in the first 700 Myr: Building Hubble's legacy of large area IR imaging for JWST and beyond

    Science.gov (United States)

    Trenti, Michele

    2017-08-01

    Hubble's WFC3 has been a game changer for the study of early galaxy formation in the first 700 Myr after the Big Bang. Reliable samples of sources to redshift z 11, which can be discovered only from space, are now constraining the evolution of the galaxy luminosity function into the epoch of reionization. Unexpectedly but excitingly, the recent spectroscopic confirmations of L>L* galaxies at z>8.5 demonstrate that objects brighter than our own Galaxy are already present 500 Myr after the Big Bang, creating a challenge to current theoretical/numerical models that struggle to explain how galaxies can grow so luminous so quickly. Yet, the existing HST observations do not cover sufficient area, nor sample a large enough diversity of environments to provide an unbiased sample of sources, especially at z 9-11 where only a handful of bright candidates are known. To double this currently insufficient sample size, to constrain effectively the bright-end of the galaxy luminosity function at z 9-10, and to provide targets for follow-up imaging and spectroscopy with JWST, we propose a large-area pure-parallel survey that will discover the Brightest of Reionizing Galaxies (BoRG[4JWST]). We will observe 580 arcmin^2 over 125 sightlines in five WFC3 bands (0.35 to 1.7 micron) using high-quality pure-parallel opportunities available in the cycle (3 orbits or longer). These public observations will identify more than 80 intrinsically bright galaxies at z 8-11, investigate the connection between halo mass, star formation and feedback in progenitors of groups and clusters, and build HST lasting legacy of large-area, near-IR imaging.

  20. Galaxy Zoo: evidence for rapid, recent quenching within a population of AGN host galaxies

    Science.gov (United States)

    Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Bamford, S. P.; Cardamone, C. N.; Kruk, S. J.; Masters, K. L.; Urry, C. M.; Willett, K. W.; Wong, O. I.

    2016-12-01

    We present a population study of the star formation history of 1244 Type 2 active galactic nuclei (AGN) host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualize the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.

  1. Are ring galaxies the ancestors of giant low surface brightness galaxies?

    NARCIS (Netherlands)

    Mapelli, M.; Moore, B.; Ripamonti, E.; Mayer, L.; Colpi, M.; Giordan, L.

    2008-01-01

    We simulate the collisional formation of a ring galaxy and we integrate its evolution up to 1.5 Gyr after the interaction. About 100-200 Myr after the collision, the simulated galaxy is very similar to observed ring galaxies (e.g. Cartwheel). After this stage, the ring keeps expanding and fades.

  2. Reactivation of pre-existing mechanical anisotropies during polyphase tectonic evolution: slip tendency analysis as a tool to constrain mechanical properties of rocks

    Science.gov (United States)

    Traforti, Anna; Bistacchi, Andrea; Massironi, Matteo; Zampieri, Dario; Di Toro, Giulio

    2017-04-01

    Intracontinental deformation within the upper crust is accommodated by nucleation of new faults (generally satisfying the Anderson's theory of faulting) or brittle reactivation of pre-existing anisotropies when certain conditions are met. How prone to reactivation an existing mechanical anisotropy or discontinuity is, depends on its mechanical strength compared to that of the intact rock and on its orientation with respect to the regional stress field. In this study, we consider how different rock types (i.e. anisotropic vs. isotropic) are deformed during a well-constrained brittle polyphase tectonic evolution to derive the mechanical strength of pre-existing anisotropies and discontinuities (i.e. metamorphic foliations and inherited faults/fractures). The analysis has been carried out in the Eastern Sierras Pampeanas of Central Argentina. These are a series of basement ranges of the Andean foreland, which show compelling evidence of a long-lasting brittle deformation history from the Early Carboniferous to Present time, with three main deformational events (Early Triassic to Early Jurassic NE-SW extension, Early Cretaceous NW-SE extension and Miocene to Present ENE-WNW compression). The study area includes both isotropic granitic bodies and anisotropic phyllosilicate-bearing rocks (gneisses and phyllites). In this environment, each deformation phase causes significant reactivation of the inherited structures and rheological anisotropies, or alternatively formation of neo-formed Andersonian faults, thus providing a multidirectional probing of mechanical properties of these rocks. A meso- and micro-structural analysis of brittle reactivation of metamorphic foliation or inherited faults/fractures revealed that different rock types present remarkable differences in the style of deformation (i.e., phyllite foliation is reactivated during the last compressional phase and cut by newly-formed Andersonian faults/fractures during the first two extensional regimes; instead

  3. Polymetamorphic evolution of the upper part of the Iezer Complex (Leaota Massif, South Carpathians) constrained by petrological data and monazite ages

    Science.gov (United States)

    Negulescu, Elena; Săbău, Gavril; Massonne, Hans-Joachim

    2015-04-01

    The Leaota Massif in Romania consists of a flat-lying sequence of five structurally concordant units displaying mutual and partly internal lithologic and metamorphic contrasts. The lower part of the lithologic sequence is the Iezer Complex, a medium-grade psammopelitic unit with a structurally concordant thin granite sill located at its upper part. The lower limit of the granite is marked discontinuously by hornfels, also present as enclaves, which experienced intense strain and a subsequent low-pressure thermal overprint. Both granite and hornfels were affected by a medium-temperature, medium- to high-pressure event (Săbău, 2000). This event was also identified in gneisses below the hornfels. These rocks contain the assemblage garnet-phengite-chloritoid-kyanite which had overprinted an older garnet-kyanite-staurolite-biotite-muscovite assemblage. Available U-Th zircon ages indicate 472.7 ± 7.3 Ma (Balintoni et al. 2009) for the granite. Monazite geochronology (Săbău & Negulescu, 2013) reveals for the associated hornfels (1) inherited ages of 528 ± 17.86 Ma overprinted by pervasive Ordovician contact metamorphism (462 ± 4.54 Ma), slightly postdating the age of magmatic zircon in the granite, (2) Silurian to Early Devonian recrystallization episodes, and (3) a Variscan medium- to high-pressure metamorphic overprint responsible for the garnet-phengite-kyanite assemblage. New petrological and geochronological data constraining the polymetamorphic evolution of the upper part of the Iezer Complex were acquired from kyanite-garnet mylonitic gneisses made up of large garnet porphyroclasts embedded in a strongly deformed matrix. Large garnets are rich in quartz, phengite, epidote, kyanite, rutile, and ilmenite inclusions. Biotite, chlorite, apatite, monazite, and Al-cerite inclusions are also present. Garnet porphyroclasts are wrapped by laminae of small garnet - white mica - biotite - quartz or zoisite - kyanite - plagioclase alternating with bands made up of fine

  4. Growing Galaxies Gently

    Science.gov (United States)

    2010-10-01

    New observations from ESO's Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang the mass of a typical galaxy increased dramatically and understanding why this happened is one of the hottest problems in modern astrophysics. The results appear in the 14 October issue of the journal Nature. The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems - including the Milky Way - that we see today. So somehow the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed. A European team of astronomers has used ESO's Very Large Telescope to test this very different idea - that young galaxies can also grow by sucking in cool streams of the hydrogen and helium gas that filled the early Universe and forming new stars from this primitive material. Just as a commercial company can expand either by merging with other companies, or by hiring more staff, young galaxies could perhaps also grow in two different ways - by merging with other galaxies or by accreting material. The team leader, Giovanni Cresci (Osservatorio Astrofisico di Arcetri) says: "The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe." The discovery will have a major impact on our understanding of the evolution of the Universe from the Big Bang to the present day. Theories of galaxy formation and evolution may have to be re-written. The group began by selecting three very distant galaxies to see if they could find evidence

  5. The Globular Cluster Systems of Nearby Edge-On Spiral Galaxies

    Science.gov (United States)

    Townsley, Leisa Kay

    1994-01-01

    Globular clusters (GC's) are well-ordered, compact groupings of stars, containing roughly 100,000 members confined to a spherical space several parsecs in diameter. They are probably a major component of every galaxy. The constituent stars are mostly metal-poor and old. The light from these objects is dominated by the emission from red giants and moderate-mass main sequence stars. About 200 GCs populate the halo of our Galaxy, showing a R1/4 falloff symmetric about the Galactic center. They may represent an earlier phase in the Milky Way's evolution, when it was still largely spherically symmetric and was only beginning to collapse to the disk seen today. These objects may be ancient even on universal time scales, constraining cosmological models of the age of the universe itself. They may comprise the closest and easiest way to study relics of the age when galaxies first formed. The Michigan State University Visual CCD Camera at the Wyoming Infrared Observatory was used to map the GC systems (GCS's) of several nearby spiral galaxies and to obtain four-filter visual photometry of the cluster's integrated light. This information will enhance our understanding of galaxy formation and the dynamics that govern galaxy evolution and allow us to explore the universality of the globular cluster luminosity function (GCLF) and its applicability to the question of the extragalactic distance scale. Three nearby, nearly edge-on spiral galaxies (NGC 4460, NGC 7640, and NGC 891) were examined. The observations confirmed the existence of GCSs in each galaxy and approached the peak of the GCLF, allowing determination of that peak using Gaussian fits. The colors were used to filter the initial point source list from each filter and to construct a GCS likelihood metric for each source, which enabled further filtering and the production of a ranked list of GC candidates for each galaxy. This metric's usefulness was confirmed using the Milky Way's GCS. The total GC population was

  6. X-Ray Binaries in Local Analogs to the First Galaxies

    Science.gov (United States)

    Brorby, Matthew G.

    2017-02-01

    The focus of this dissertation is to investigate the effect of metallicity on high-mass X-ray binary (HMXB) formation and evolution as a means to understand the evolution of the early Universe (z > 6). Understanding the population and X-ray output of HMXBs are vital to modelling the heating and ionization morphology of the intergalactic medium during the epoch of reionization. Current X-ray instruments are unable to directly detect very high redshift HMXBs, making it impossible to constrain population sizes in this way. Instead certain local galaxies may be used as analogs to infer the properties of galaxies in the early Universe. These local analogs should have properties consistent with those expected for the first galaxies, such as low-metallicity, compact morphology, and intense recent star formation. I present an X-ray population study of 25 blue compact dwarf galaxies (BCD), using multiwavelength data and Bayesian analysis techniques. We find a significant enhancement of the HMXB population in low-metallicity environments and suggest the same may be true in the early Universe. I continue the investigation of HMXB populations in a sample of 10 moderate metallicity (Z ≥ 0.3, Z solar masses), local star-forming galaxies known as Lyman Break Analogs (LBAs). I find evidence of a LX-SFR-metallicity plane in the combined sample of BCDs, LBAs, and regular star-forming galaxies. Then I study a third type of local analog to early Universe galaxies, the Green Pea galaxies. These are a subclass of luminous compact galaxies (LCGs) which show strong [OIII]lambda5007A emission indicative of extreme, recent star-formation. This pilot study was carried out to look, for the first time in X-rays, at this recently established class of galaxies and use them to test the LX-SFR-metallicity plane. Determining the spectral properties of bright HMXBs in low-metallicity environments also has important implications for models of X-ray heating leading up to the Epoch of Reionization. I

  7. Statistical study of some Lee galaxy groups

    Science.gov (United States)

    Mohamed, Sabry A.; Fouad, Ahmed M.

    2017-12-01

    Compact groups of galaxies are systems of small number of galaxies close to each other. They are a good laboratory to study galaxy properties, such as structure, morphology and evolution which are affected by the environment and galaxy interactions. We applied the tree clustering technique (the Euclidean separation distance coefficients) to test the physical reality of groups and used certain criteria (Sabry et al., 2009) depending on the physical attributes of the galaxies. The sample of the data is the quintets groups of Lee compact groups of galaxies (Lee et al., 2004). It is based on a modified version of Hickson's criteria (Hickson, 1982). The results reveal the membership of each galaxy and how it is related to its group. The tables of groups and their members are included. Our results indicates that 12 Groups are real groups with real members while 18 Groups have one galaxy that has attribute discordant and should be discarded from its group.

  8. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Star formation history of passive red galaxies

    Science.gov (United States)

    Siudek, M.; Małek, K.; Scodeggio, M.; Garilli, B.; Pollo, A.; Haines, C. P.; Fritz, A.; Bolzonella, M.; de la Torre, S.; Granett, B. R.; Guzzo, L.; Abbas, U.; Adami, C.; Bottini, D.; Cappi, A.; Cucciati, O.; De Lucia, G.; Davidzon, I.; Franzetti, P.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Marchetti, A.; Marulli, F.; Polletta, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Arnouts, S.; Bel, J.; Branchini, E.; Ilbert, O.; Gargiulo, A.; Moscardini, L.; Takeuchi, T. T.; Zamorani, G.

    2017-01-01

    Aims: We trace the evolution and the star formation history of passive red galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). The detailed spectral analysis of stellar populations of intermediate-redshift passive red galaxies allows the build up of their stellar content to be followed over the last 8 billion years. Methods: We extracted a sample of passive red galaxies in the redshift range 0.4 history of passive red galaxies. We compare the results with a grid of synthetic spectra to constrain the star formation epochs of these galaxies. We characterize the formation redshift-stellar mass relation for intermediate-redshift passive red galaxies. Results: We find that at z 1 stellar populations in low-mass passive red galaxies are younger than in high-mass passive red galaxies, similar to what is observed at the present epoch. Over the full analyzed redshift range 0.4 time passes, I.e., what has become known as the downsizing picture. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it/

  9. CI as a Tracer of Gas Mass in Star Forming Galaxies

    Science.gov (United States)

    Bourne, Nathan

    2018-01-01

    Research in galaxy evolution aims to understand the cosmic industry of converting gas into stars. While SFR and stellar mass evolution are well constrained by current data, our knowledge of gas in galaxies throughout cosmic time is comparatively lacking. Almost all high-redshift gas measurements to date rely on CO as a tracer, but this is subject to systematic uncertainties due to optically thick emission and poorly constrained dependences on gas density, distribution and metallicity. Recently, some attention has been given to dust continuum as an alternative gas tracer, which shows promise for large samples but still requires accurate calibration on a direct gas tracer at high redshift. The [CI] 492GHz emission line could overcome much of the systematic uncertainty, as it is optically thin and has similar excitation conditions to CO(1-0), but observational limitations have so far restricted CI measurements to very small samples. I will presen t some new data from ALMA, for the first time testing the CI/dust correlation in a representative sample of star-forming galaxies at z=1, and discuss how future observations could be designed to more widely exploit this independent gas tracer.

  10. Hubble Space Telescope Hx Imaging of Star-forming Galaxies at z approximately equal to 1-1.5: Evolution in the Size and Luminosity of Giant H II Regions

    Science.gov (United States)

    Livermore, R. C.; Jones, T.; Richard, J.; Bower, R. G.; Ellis, R. S.; Swinbank, A. M.; Rigby, J. R.; Smail, Ian; Arribas, S.; Rodriguez-Zaurin, J.; hide

    2013-01-01

    We present Hubble Space Telescope/Wide Field Camera 3 narrow-band imaging of the Ha emission in a sample of eight gravitationally lensed galaxies at z = 1-1.5. The magnification caused by the foreground clusters enables us to obtain a median source plane spatial resolution of 360 pc, as well as providing magnifications in flux ranging from approximately 10× to approximately 50×. This enables us to identify resolved star-forming HII regions at this epoch and therefore study their Ha luminosity distributions for comparisons with equivalent samples at z approximately 2 and in the local Universe. We find evolution in the both luminosity and surface brightness of HII regions with redshift. The distribution of clump properties can be quantified with an HII region luminosity function, which can be fit by a power law with an exponential break at some cut-off, and we find that the cut-off evolves with redshift. We therefore conclude that 'clumpy' galaxies are seen at high redshift because of the evolution of the cut-off mass; the galaxies themselves follow similar scaling relations to those at z = 0, but their HII regions are larger and brighter and thus appear as clumps which dominate the morphology of the galaxy. A simple theoretical argument based on gas collapsing on scales of the Jeans mass in a marginally unstable disc shows that the clumpy morphologies of high-z galaxies are driven by the competing effects of higher gas fractions causing perturbations on larger scales, partially compensated by higher epicyclic frequencies which stabilize the disc.

  11. The tree balance signature of mass extinction is erased by continued evolution in clades of constrained size with trait-dependent speciation

    OpenAIRE

    Guan-Dong Yang; Paul-Michael Agapow; Gabriel Yedid

    2017-01-01

    The kind and duration of phylogenetic topological "signatures" left in the wake of macroevolutionary events remain poorly understood. To this end, we examined a broad range of simulated phylogenies generated using trait-biased, heritable speciation probabilities and mass extinction that could be either random or selective on trait value, but also using background extinction and diversity-dependence to constrain clade sizes. In keeping with prior results, random mass extinction increased imbal...

  12. Star-Formation Histories of MUSCEL Galaxies

    Science.gov (United States)

    Young, Jason; Kuzio de Naray, Rachel; Xuesong Wang, Sharon

    2018-01-01

    The MUSCEL program (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies) uses combined ground-based/space-based data to determine the spatially resolved star-formation histories of low surface brightness (LSB) galaxies. LSB galaxies are paradoxical in that they are gas rich but have low star-formation rates. Here we present our observations and fitting technique, and the derived histories for select MUSCEL galaxies. It is our aim to use these histories in tandem with velocity fields and metallicity profiles to determine the physical mechanism(s) that give these faint galaxies low star-formation rates despite ample gas supplies.

  13. PEARS Emission Line Galaxies

    Science.gov (United States)

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Rhoads, James E.; Malhotra, Sangeeta; Grogin, Norman A.; Dahlen, Tomas; Meurer, Gerhardt R.; Walsh, Jeremy; Hathi, Nimish P.; hide

    2012-01-01

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitless grism spectroscopic data obtained vl'ith the Advanced Camera for Surveys on HST. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random surveY of galaxies, as well as the availability of a wide variety of ancillary observations to support the spectroscopic results. Using the PEARS data we are able to identify star forming galaxies within the redshift volume 0 = 10(exp 9) Solar M decreases by an order of magnitude at z<=0.5 relative to the number at 0.5 < z < 0.9 in support of the argument for galaxy downsizing.

  14. Seeing Baby Dwarf Galaxies

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] [figure removed for brevity, see original site] Visible/DSS Click on image for larger version Ultraviolet/GALEX Click on image for larger version Poster Version Click on image for larger version The unique ultraviolet vision of NASA's Galaxy Evolution Explorer reveals, for the first time, dwarf galaxies forming out of nothing more than pristine gas likely leftover from the early universe. Dwarf galaxies are relatively small collections of stars that often orbit around larger galaxies like our Milky Way. The forming dwarf galaxies shine in the far ultraviolet spectrum, rendered as blue in the call-out on the right hand side of this image. Near ultraviolet light, also obtained by the Galaxy Evolution Explorer, is displayed in green, and visible light from the blue part of the spectrum here is represented by red. The clumps (in circles) are distinctively blue, indicating they are primarily detected in far ultraviolet light. The faint blue overlay traces the outline of the Leo Ring, a huge cloud of hydrogen and helium that orbits around two massive galaxies in the constellation Leo (left panel). The cloud is thought likely to be a primordial object, an ancient remnant of material that has remained relatively unchanged since the very earliest days of the universe. Identified about 25 years ago by radio waves, the ring cannot be seen in visible light. Only a portion of the Leo Ring has been imaged in the ultraviolet, but this section contains the telltale ultraviolet signature of recent massive star formation within this ring of pristine gas. Astronomers have previously only seen dwarf galaxies form out of gas that has already been cycled through a galaxy and enriched with metals elements heavier than helium produced as stars evolve. The visible data come from the Digitized Sky Survey of the Space Telescope Science Institute in Baltimore, Md. The Leo Ring visible image (left

  15. Globular Clusters - Guides to Galaxies

    CERN Document Server

    Richtler, Tom; Joint ESO-FONDAP Workshop on Globular Clusters

    2009-01-01

    The principal question of whether and how globular clusters can contribute to a better understanding of galaxy formation and evolution is perhaps the main driving force behind the overall endeavour of studying globular cluster systems. Naturally, this splits up into many individual problems. The objective of the Joint ESO-FONDAP Workshop on Globular Clusters - Guides to Galaxies was to bring together researchers, both observational and theoretical, to present and discuss the most recent results. Topics covered in these proceedings are: internal dynamics of globular clusters and interaction with host galaxies (tidal tails, evolution of cluster masses), accretion of globular clusters, detailed descriptions of nearby cluster systems, ultracompact dwarfs, formations of massive clusters in mergers and elsewhere, the ACS Virgo survey, galaxy formation and globular clusters, dynamics and kinematics of globular cluster systems and dark matter-related problems. With its wide coverage of the topic, this book constitute...

  16. The Impact of Star Formation Histories on Stellar Mass Estimation: Implications from the Local Group Dwarf Galaxies

    Science.gov (United States)

    Zhang, Hong-Xin; Puzia, Thomas H.; Weisz, Daniel R.

    2017-11-01

    Building on the relatively accurate star formation histories (SFHs) and metallicity evolution of 40 Local Group (LG) dwarf galaxies derived from resolved color-magnitude diagram modeling, we carried out a comprehensive study of the influence of SFHs, metallicity evolution, and dust extinction on the UV-to-near-IR color-mass-to-light ratio (color-{log}{{{\\Upsilon }}}\\star (λ)) distributions and M ⋆ estimation of local universe galaxies. We find that (1) the LG galaxies follow color-{log}{{{\\Upsilon }}}\\star (λ) relations that fall in between the ones calibrated by previous studies; (2) optical color-{log}{{{\\Upsilon }}}\\star (λ) relations at higher [M/H] are generally broader and steeper; (3) the SFH “concentration” does not significantly affect the color-{log}{{{\\Upsilon }}}\\star (λ) relations; (4) light-weighted ages }λ and metallicities }λ together constrain {log}{{{\\Upsilon }}}\\star (λ) with uncertainties ranging from ≲0.1 dex for the near-IR up to 0.2 dex for the optical passbands; (5) metallicity evolution induces significant uncertainties to the optical but not near-IR {{{\\Upsilon }}}\\star (λ) at a given }λ and }λ ; (6) the V band is the ideal luminance passband for estimating {{{\\Upsilon }}}\\star (λ) from single colors, because the combinations of {{{\\Upsilon }}}\\star (V) and optical colors such as B - V and g - r exhibit the weakest systematic dependences on SFHs, metallicities, and dust extinction; and (7) without any prior assumption on SFHs, M ⋆ is constrained with biases ≲0.3 dex by the optical-to-near-IR SED fitting. Optical passbands alone constrain M ⋆ with biases ≲0.4 dex (or ≲0.6 dex) when dust extinction is fixed (or variable) in SED fitting. SED fitting with monometallic SFH models tends to underestimate M ⋆ of real galaxies. M ⋆ tends to be overestimated (or underestimated) at the youngest (or oldest) }{mass}.

  17. Tidal alignment of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš

    2015-08-01

    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used "nonlinear alignment model," finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the "GI" term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  18. Stellar mass and population diagnostics of cluster galaxies

    Science.gov (United States)

    Roediger, Joel C.

    2013-12-01

    We conduct a broad investigation about stellar mass and population diagnostics in order to formulate novel constraints related to the formation and evolution of galaxies from a nearby cluster environment. Our work is powered by the use of stellar population models which transform galaxy colours and/or absorption line strengths into estimates of its stellar properties. As input to such models, we assemble an extensive compilation of age and chemical abundance information for Galactic globular clusters. This compilation allows a confident expansion of these models into new regions of parameter space that promise to refine our knowledge of galactic chemical evolution. We then draw upon a state-of-the-art spectroscopic and photometric survey of the Virgo galaxy cluster in order to constrain spatial variations of the stellar ages, metallicities, and masses within its member galaxies, and their dynamical masses. We interpret these data in the context of the histories of star formation, chemical enrichment, and stellar mass assembly to formulate a broad picture of the build-up of this cluster's content over time. In it, the giant early-type galaxies formed through highly dissipational processes at early times that built up most of their stellar mass and drew significant amounts of dark matter within their optical radii. Conversely, dwarf early-types experienced environmental processes that quenched their star formation during either the early stages of cluster assembly or upon infall at later times. Somewhat perplexing is our finding that the internal dynamics of these galaxies are largely explained by their stellar masses. Lastly, Virgo spirals also suffer from their dense environment, through ram pressure stripping and/or tidal harrassment. In addition to quenching, these effects leave an imprint on their internal dynamical evolution too. Late-type spirals exhibit evidence of having ejected significant amounts of baryons from their inner regions, likely via energetic

  19. The SAURON Project - XIV. No escape from V-esc : a global and local parameter in early-type galaxy evolution

    NARCIS (Netherlands)

    Scott, Nicholas; Cappellari, Michele; Davies, Roger L.; Bacon, R.; de Zeeuw, P. T.; Emsellem, Eric; Falcon-Barroso, Jesus; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; Pipino, Antonio; Sarzi, Marc; van den Bosch, Remco C. E.; van de Ven, Glenn; van Scherpenzeel, Eveline; Krajnović, Davor

    2009-01-01

    We present the results of an investigation of the local escape velocity (V-esc) - line strength index relationship for 48 early-type galaxies from the SAURON sample, the first such study based on a large sample of galaxies with both detailed integral field observations and extensive dynamical

  20. The Survey of HI in Extremely Low-mass Dwarfs: A Multi-Wavelength Perspective on Low-Mass Galaxy Evolution

    NARCIS (Netherlands)

    Cannon, John M.; McNichols, Andrew; Teich, Yaron; Adams, Elizabeth A.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Salzer, John Joseph; Skillman, Evan D.; Dolphin, Andrew E.; Elson, Edward C.; Haurberg, Nathalie C.; Huang, Shan; Janowiecki, Steven; Jozsa, Gyula; Leisman, Luke; Ott, Juergen; Papastergis, Emmanouil; Rhode, Katherine L.; Saintonge, Amelie; Van Sistine, Angela; Warren, Steven R.

    2017-01-01

    The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies drawn from the Arecibo Legacy Fast ALFA (ALFALFA) catalog. HST/Spitzer joint program GO-12658 revealed the stellar populations of the first 12 SHIELD galaxies (Cannon et al. 2011),

  1. zCOSMOS-10k-bright spectroscopic sample. The bimodality in the galaxy stellar mass function : Exploring its evolution with redshift

    NARCIS (Netherlands)

    Pozzetti, L.; Bolzonella, M.; Zucca, E.; Zamorani, G.; Lilly, S.; Renzini, A.; Moresco, M.; Mignoli, M.; Cassata, P.; Tasca, L.; Lamareille, F.; Maier, C.; Meneux, B.; Halliday, C.; Oesch, P.; Vergani, D.; Caputi, K.; Kovac, K.; Cimatti, A.; Cucciati, O.; Iovino, A.; Peng, Y.; Carollo, M.; Contini, T.; P. Kneib, J.; Le F'evre, O.; Mainieri, V.; Scodeggio, M.; Bardelli, S.; Bongiorno, A.; Coppa, G.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Kampczyk, P.; Knobel, C.; F. Le Borgne, J.; Le Brun, V.; Pell`o, R.; Perez Montero, E.; Ricciardelli, E.; D. Silverman, J.; Tanaka, M.; Tresse, L.; Abbas, U.; Bottini, D.; Cappi, A.; Guzzo, L.; M. Koekemoer, A.; Leauthaud, A.; Maccagni, D.; Marinoni, C.; J. McCracken, H.; Memeo, P.; Porciani, C.; Scaramella, R.; Scarlata, C.; Scoville, N.

    2010-01-01

    We present the galaxy stellar mass function (GSMF) to redshift z similar or equal to 1, based on the analysis of about 8500 galaxies with I <22.5 (AB mag) over 1.4 deg(2), which are part of the zCOSMOS-bright 10k spectroscopic sample. We investigate the total GSMF, as well as the contributions of

  2. The evolution of the stellar mass functions of star-forming and quiescent galaxies to z = 4 from the COSMOS/ultraVISTA survey

    DEFF Research Database (Denmark)

    Muzzin, Adam; Marchesini, Danilo; Stefano, Mauro

    2013-01-01

    We present measurements of the stellar mass functions (SMFs) of star-forming and quiescent galaxies to z = 4 using a sample of 95,675 Ks -selected galaxies in the COSMOS/UltraVISTA field. The SMFs of the combined population are in good agreement with previous measurements and show that the stellar...

  3. CLASH-VLT: The stellar mass function and stellar mass density profile of the z=0.44 cluster of galaxies MACS J1206.2-0847

    CERN Document Server

    Annunziatella, M; Mercurio, A.; Nonino, M.; Rosati, P.; Balestra, I.; Presotto, V.; Girardi, M.; Gobat, R.; Grillo, C.; Medezinski, E.; Kelson, D.; Postman, M.; Scodeggio, M.; Brescia, M.; Sartoris, B.; Demarco, R.; Fritz, A.; Koekemoer, A.; Lemze, D.; Lombardi, M.; Bradley, L.; Coe, D.; Donahue, M.; Regös, E.; Umetsu, K.; Vanzella, E.; Infante, L.; Kuchner, U.; Maier, C.; Verdugo, M.; Ziegler, B.

    2014-01-01

    Context. The study of the galaxy stellar mass function (SMF) in relation to the galaxy environment and the stellar mass density profile, rho(r), is a powerful tool to constrain models of galaxy evolution. Aims. We determine the SMF of the z=0.44 cluster of galaxies MACS J1206.2-0847 separately for passive and star-forming (SF) galaxies, in different regions of the cluster, from the center out to approximately 2 virial radii. We also determine rho(r) to compare it to the number density and total mass density profiles. Methods. We use the dataset from the CLASH-VLT survey. Stellar masses are obtained by SED fitting on 5-band photometric data obtained at the Subaru telescope. We identify 1363 cluster members down to a stellar mass of 10^9.5 Msolar. Results. The whole cluster SMF is well fitted by a double Schechter function. The SMFs of cluster SF and passive galaxies are statistically different. The SMF of the SF cluster galaxies does not depend on the environment. The SMF of the passive population has a signif...

  4. Thick Disks of Lenticular Galaxies

    OpenAIRE

    Pohlen, M.; Balcells, M.; Luetticke, R.; Dettmar, R. -J.

    2004-01-01

    Thick disks are faint and extended stellar components found around several disk galaxies including our Milky Way. The Milky Way thick disk, the only one studied in detail, contains mostly old disk stars (~10 Gyr), so that thick disks are likely to trace the early stages of disk evolution. Previous detections of thick disk stellar light in external galaxies have been originally made for early-type, edge-on galaxies but detailed 2D thick/thin disk decompositions have been reported for only a sc...

  5. Automatic Approach to Morphological Classification of Galaxies With Analysis of Galaxy Populations in Clusters

    Science.gov (United States)

    Sultanova, Madina; Barkhouse, Wayne; Rude, Cody

    2018-01-01

    The classification of galaxies based on their morphology is a field in astrophysics that aims to understand galaxy formation and evolution based on their physical differences. Whether structural differences are due to internal factors or a result of local environment, the dominate mechanism that determines galaxy type needs to be robustly quantified in order to have a thorough grasp of the origin of the different types of galaxies. The main subject of my Ph.D. dissertation is to explore the use of computers to automatically classify and analyze large numbers of galaxies according to their morphology, and to analyze sub-samples of galaxies selected by type to understand galaxy formation in various environments. I have developed a computer code to classify galaxies by measuring five parameters from their images in FITS format. The code was trained and tested using visually classified SDSS galaxies from Galaxy Zoo and the EFIGI data set. I apply my morphology software to numerous galaxies from diverse data sets. Among the data analyzed are the 15 Abell galaxy clusters (0.03 software to examine the properties (e.g. luminosity functions, radial dependencies, star formation rates) of selected galaxies. Due to the large amount of data that will be available from wide-area surveys in the future, the use of computer software to classify and analyze the morphology of galaxies will be extremely important in terms of efficiency. This research aims to contribute to the solution of this problem.

  6. The Evolution of the Stellar Mass Functions of Star-forming and Quiescent Galaxies to z = 4 from the COSMOS/UltraVISTA Survey

    Science.gov (United States)

    Muzzin, Adam; Marchesini, Danilo; Stefanon, Mauro; Franx, Marijn; McCracken, Henry J.; Milvang-Jensen, Bo; Dunlop, James S.; Fynbo, J. P. U.; Brammer, Gabriel; Labbé, Ivo; van Dokkum, Pieter G.

    2013-11-01

    We present measurements of the stellar mass functions (SMFs) of star-forming and quiescent galaxies to z = 4 using a sample of 95,675 Ks -selected galaxies in the COSMOS/UltraVISTA field. The SMFs of the combined population are in good agreement with previous measurements and show that the stellar mass density of the universe was only 50%, 10%, and 1% of its current value at z ~ 0.75, 2.0, and 3.5, respectively. The quiescent population drives most of the overall growth, with the stellar mass density of these galaxies increasing as ρstarvprop(1 + z)-4.7 ± 0.4 since z = 3.5, whereas the mass density of star-forming galaxies increases as ρstarvprop(1 + z)-2.3 ± 0.2. At z > 2.5, star-forming galaxies dominate the total SMF at all stellar masses, although a non-zero population of quiescent galaxies persists to z = 4. Comparisons of the Ks -selected star-forming galaxy SMFs with UV-selected SMFs at 2.5 3.5. We estimate the average mass growth of individual galaxies by selecting galaxies at fixed cumulative number density. The average galaxy with log(M star/M ⊙) = 11.5 at z = 0.3 has grown in mass by only 0.2 dex (0.3 dex) since z = 2.0 (3.5), whereas those with log(M star/M ⊙) = 10.5 have grown by >1.0 dex since z = 2. At z budget in the SMFs. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium.

  7. Stellar populations of shell galaxies

    Science.gov (United States)

    Carlsten, S. G.; Hau, G. K. T.; Zenteno, A.

    2017-12-01

    We present a study of the inner (out to ∼1 Reff) stellar populations of nine shell galaxies. We derive stellar population parameters from long-slit spectra by both analysing the Lick indices of the galaxies and by fitting single stellar population model spectra to the full galaxy spectra. The results from the two methods agree reasonably well. A few of the shell galaxies appear to have lower central Mg2 index values than the general population of galaxies of the same central velocity dispersion, which is possibly due to a past interaction event. Our sample shows a relation between central metallicity and velocity dispersion that is consistent with previous samples of non-shell galaxies. Analysing the metallicity gradients in our sample, we find an average gradient of -0.16 ± 0.10 dex decade-1 in radius. We compare this with formation models to constrain the merging history of shell galaxies. We argue that our galaxies likely have undergone major mergers but it is unclear whether the shells formed from these events or from separate minor mergers. Additionally, we find evidence for young stellar populations ranging in age from 500 Myr to 4-5 Gyr in four of the galaxies, allowing us to speculate on the age of the shells. For NGC 5670, we use a simple dynamical model to find the time required to produce the observed distribution of shells to be roughly consistent with the age of the young subpopulation, suggesting that the shells and subpopulation possibly formed from the same event.

  8. Galaxies with "rows": A new catalog

    Science.gov (United States)

    Butenko, M. A.; Khoperskov, A. V.

    2017-07-01

    Galaxies with "rows" in Vorontsov-Velyaminov's terminology stand out among the variety of spiral galactic patterns. A characteristic feature of such objects is the sequence of straight-line segments that forms the spiral arm. In 2001 A. Chernin and co-authors published a catalog of such galaxies which includes 204 objects from the Palomar Atlas. In this paper, we supplement the catalog with 276 objects based on an analysis of all the galaxies from the New General Catalogue and Index Catalogue. The total number of NGC and IC galaxies with rows is 406, including the objects of Chernin et al. (2001). The use of more recent galaxy images allowed us to detect more "rows" on average, compared with the catalog of Chernin et al. When comparing the principal galaxy properties we found no significant differences between galaxies with rows and all S-typeNGC/IC galaxies.We discuss twomechanisms for the formation of polygonal structures based on numerical gas-dynamic and collisionless N-body calculations, which demonstrate that a spiral pattern with rows is a transient stage in the evolution of galaxies and a system with a powerful spiral structure can pass through this stage. The hypothesis of A. Chernin et al. (2001) that the occurrence frequency of interacting galaxies is twice higher among galaxies with rows is not confirmed for the combined set of 480 galaxies. The presence of a central stellar bar appears to be a favorable factor for the formation of a system of "rows".

  9. Dust in External Galaxies

    OpenAIRE

    Calzetti, Daniela

    2009-01-01

    Existing (Spitzer Space Telescope) and upcoming (Herschel Space Telescope) facilities are deepening our understanding of the role of dust in tracing the energy budget and chemical evolution of galaxies. The tools we are developing while exploring the local Universe will in turn become pivotal in the interpretation of the high redshift Universe when near--future facilities (the Atacama Large Millimeter Array [ALMA], the Sub--Millimeter Array [SMA], the Large Millimeter Telescope [LMT], the Jam...

  10. Constraining the Depth of Polar Ice Deposits and Evolution of Cold Traps on Mercury with Small Craters in Permanently Shadowed Regions

    Science.gov (United States)

    Deutsch, Ariel N.; Head, James W.; Neumann, Gregory A.; Chabot, Nancy L.

    2017-01-01

    Earth-based radar observations revealed highly reflective deposits at the poles of Mercury [e.g., 1], which collocate with permanently shadowed regions (PSRs) detected from both imagery and altimetry by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft [e.g., 2]. MESSENGER also measured higher hydrogen concentrations at the north polar region, consistent with models for these deposits to be composed primarily of water ice [3]. Enigmatic to the characterization of ice deposits on Mercury is the thickness of these radar-bright features. A current minimum bound of several meters exists from the radar measurements, which show no drop in the radar cross section between 13- and 70-cm wavelength observations [4, 5]. A maximum thickness of 300 m is based on the lack of any statistically significant difference between the height of craters that host radar-bright deposits and those that do not [6]. More recently, this upper limit on the depth of a typical ice deposit has been lowered to approximately 150 m, in a study that found a mean excess thickness of 50 +/- 35 m of radar-bright deposits for 6 craters [7]. Refining such a constraint permits the derivation of a volumetric estimate of the total polar ice on Mercury, thus providing insight into possible sources of water ice on the planet. Here, we take a different approach to constrain the thickness of water-ice deposits. Permanently shadowed surfaces have been resolved in images acquired with the broadband filter on MESSENGER's wide-angle camera (WAC) using low levels of light scattered by crater walls and other topography [8]. These surfaces are not featureless and often host small craters (less than a few km in diameter). Here we utilize the presence of these small simple craters to constrain the thickness of the radar-bright ice deposits on Mercury. Specifically, we compare estimated depths made from depth-to-diameter ratios and depths from individual Mercury Laser Altimeter (MLA

  11. Colours, luminosity functions and counts of galaxies

    Science.gov (United States)

    Saracco, P.; Chincarini, G.; Iovino, A.

    1996-12-01

    Standard models for deep galaxy counts are based on luminosity functions (LFs) that have a relatively flat faint end (alpha~-1.0). Galaxy counts in the B band exceed the prediction of such models from a factor of 2 to more than a factor of 5, forcing the introduction of strong luminosity and/or density evolution. Recently Marzke, Huchra & Geller, using the CfA redshift survey sample, found that the number of galaxies in the range -16<2.5 for dwarf galaxies, we reproduce well also the observed K-band deep galaxy counts. This assumption is supported by the strong correlation we found between B-K colour of galaxies and their infrared absolute magnitude: galaxies become bluer with decreasing luminosity.

  12. Growing up in a megalopolis: Environmental effects on galaxy evolution in a supercluster at z ˜ 0.65 in UKIDSS UDS★

    Science.gov (United States)

    Galametz, Audrey; Pentericci, Laura; Castellano, Marco; Mendel, Trevor; Hartley, Will G.; Fossati, Matteo; Finoguenov, Alexis; Almaini, Omar; Beifiori, Alessandra; Fontana, Adriano; Grazian, Andrea; Scodeggio, Marco; Kocevski, Dale D.

    2018-01-01

    We present a large-scale galaxy structure Cl J021734-0513 at z ˜ 0.65 discovered in the UKIDSS UDS field, made of ˜20 galaxy groups and clusters, spreading over 10 Mpc. We report on a VLT/VIMOS spectroscopic follow-up program that, combined with past spectroscopy, allowed us to confirm four galaxy clusters (M200 ˜ 1014 M⊙) and a dozen associated groups and star-forming galaxy overdensities. Two additional filamentary structures at z ˜ 0.62 and z ˜ 0.69 and foreground and background clusters at 0.6 mix of star-forming galaxy overdensities and forming groups. The presence of quiescent galaxies in the core of the latter shows that ?preprocessing? has already happened before the groups fall into their more massive neighbours. Our spectroscopy allows us to derive spectral index measurements e.g. emission/absorption line equivalent widths, strength of the 4000Å break, valuable to investigate the star formation history of structure members. Based on these line measurements, we select a population of ?post-starburst? galaxies. These galaxies are preferentially found within the virial radius of clusters, supporting a scenario in which their recent quenching could be prompted by gas stripping by the dense intracluster medium. We derive stellar age estimates using MCMC-based spectral fitting for quiescent galaxies and find a correlation between ages and colours/stellar masses which favours a top-down formation scenario of the red sequence. A catalogue of ˜650 redshifts in UDS will be released alongside the paper.

  13. A SUBSTANTIAL POPULATION OF MASSIVE QUIESCENT GALAXIES AT z ∼ 4 FROM ZFOURGE

    Energy Technology Data Exchange (ETDEWEB)

    Straatman, Caroline M. S.; Labbé, Ivo [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Spitler, Lee R. [Department of Physics and Astronomy, Faculty of Sciences, Macquarie University, Sydney, NSW 2109 (Australia); Allen, Rebecca; Glazebrook, Karl; Kacprzak, Glenn G. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Altieri, Bruno [European Space Astronomy Centre (ESAC)/ESA, Villanueva de la Cañada, 28691, Madrid (Spain); Brammer, Gabriel B. [European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago (Chile); Dickinson, Mark; Inami, Hanae [National Optical Astronomy Observatory, Tucson, AZ (United States); Van Dokkum, Pieter [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Kawinwanichakij, Lalit; Mehrtens, Nicola; Papovich, Casey [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Kelson, Daniel D.; McCarthy, Patrick J.; Monson, Andy; Murphy, David; Persson, S. Eric; Quadri, Ryan, E-mail: straatman@strw.leidenuniv.nl [Carnegie Observatories, Pasadena, CA 91101 (United States); and others

    2014-03-01

    We report the likely identification of a substantial population of massive M ∼ 10{sup 11} M {sub ☉} galaxies at z ∼ 4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey (ZFOURGE). The observed spectral energy distributions show pronounced breaks, sampled by a set of near-IR medium-bandwidth filters, resulting in tightly constrained photometric redshifts. Fitting stellar population models suggests large Balmer/4000 Å breaks, relatively old stellar populations, large stellar masses, and low SFRs, with a median specific SFR of 2.9 ± 1.8 × 10{sup –11} yr{sup –1}. Ultradeep Herschel/PACS 100 μm, 160 μm and Spitzer/MIPS 24 μm data reveal no dust-obscured SFR activity for 15/19(79%) galaxies. Two far-IR detected galaxies are obscured QSOs. Stacking the far-IR undetected galaxies yields no detection, consistent with the spectral energy distribution fit, indicating independently that the average specific SFR is at least 10 × smaller than that of typical star-forming galaxies at z ∼ 4. Assuming all far-IR undetected galaxies are indeed quiescent, the volume density is 1.8 ± 0.7 × 10{sup –5} Mpc{sup –3} to a limit of log{sub 10} M/M {sub ☉} ≥ 10.6, which is 10 × and 80 × lower than at z = 2 and z = 0.1. They comprise a remarkably high fraction (∼35%) of z ∼ 4 massive galaxies, suggesting that suppression of star formation was efficient even at very high redshift. Given the average stellar age of 0.8 Gyr and stellar mass of 0.8 × 10{sup 11} M {sub ☉}, the galaxies likely started forming stars before z = 5, with SFRs well in excess of 100 M {sub ☉} yr{sup –1}, far exceeding that of similarly abundant UV-bright galaxies at z ≥ 4. This suggests that most of the star formation in the progenitors of quiescent z ∼ 4 galaxies was obscured by dust.