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Sample records for growing massive black

  1. Massive Black Holes and Galaxies

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discuss measurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.

  2. The Formation and Evolution of the First Massive Black Holes

    OpenAIRE

    Haiman, Zoltan; Quataert, Eliot

    2004-01-01

    The first massive astrophysical black holes likely formed at high redshifts (z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations. These black holes grow by mergers and gas accretion, evolve into the population of bright quasars observed at lower redshifts, and eventually leave the supermassive black hole remnants that are ubiquitous at the centers of galaxies in the nearby universe. The astrophysical processes responsible for the formation of the earliest seed black holes...

  3. Massive Binary Black Holes in the Cosmic Landscape

    OpenAIRE

    Colpi, M.; Dotti, M.

    2009-01-01

    Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly. But, if the black holes reach coalescence, then they become the loudest sources of gravitational waves ever in the universe. Nature seems to provide a pathway for the formation of these ex...

  4. Reconstructing the massive black hole cosmic history through gravitational waves

    International Nuclear Information System (INIS)

    Sesana, Alberto; Gair, Jonathan; Berti, Emanuele; Volonteri, Marta

    2011-01-01

    The massive black holes we observe in galaxies today are the natural end-product of a complex evolutionary path, in which black holes seeded in proto-galaxies at high redshift grow through cosmic history via a sequence of mergers and accretion episodes. Electromagnetic observations probe a small subset of the population of massive black holes (namely, those that are active or those that are very close to us), but planned space-based gravitational wave observatories such as the Laser Interferometer Space Antenna (LISA) can measure the parameters of 'electromagnetically invisible' massive black holes out to high redshift. In this paper we introduce a Bayesian framework to analyze the information that can be gathered from a set of such measurements. Our goal is to connect a set of massive black hole binary merger observations to the underlying model of massive black hole formation. In other words, given a set of observed massive black hole coalescences, we assess what information can be extracted about the underlying massive black hole population model. For concreteness we consider ten specific models of massive black hole formation, chosen to probe four important (and largely unconstrained) aspects of the input physics used in structure formation simulations: seed formation, metallicity ''feedback'', accretion efficiency and accretion geometry. For the first time we allow for the possibility of 'model mixing', by drawing the observed population from some combination of the 'pure' models that have been simulated. A Bayesian analysis allows us to recover a posterior probability distribution for the ''mixing parameters'' that characterize the fractions of each model represented in the observed distribution. Our work shows that LISA has enormous potential to probe the underlying physics of structure formation.

  5. Massive Black Hole Binary Evolution

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    Merritt David

    2005-11-01

    Full Text Available Coalescence of binary supermassive black holes (SBHs would constitute the strongest sources of gravitational waves to be observed by LISA. While the formation of binary SBHs during galaxy mergers is almost inevitable, coalescence requires that the separation between binary components first drop by a few orders of magnitude, due presumably to interaction of the binary with stars and gas in a galactic nucleus. This article reviews the observational evidence for binary SBHs and discusses how they would evolve. No completely convincing case of a bound, binary SBH has yet been found, although a handful of systems (e.g. interacting galaxies; remnants of galaxy mergers are now believed to contain two SBHs at projected separations of <~ 1kpc. N-body studies of binary evolution in gas-free galaxies have reached large enough particle numbers to reproduce the slow, “diffusive” refilling of the binary’s loss cone that is believed to characterize binary evolution in real galactic nuclei. While some of the results of these simulations - e.g. the binary hardening rate and eccentricity evolution - are strongly N-dependent, others - e.g. the “damage” inflicted by the binary on the nucleus - are not. Luminous early-type galaxies often exhibit depleted cores with masses of ~ 1-2 times the mass of their nuclear SBHs, consistent with the predictions of the binary model. Studies of the interaction of massive binaries with gas are still in their infancy, although much progress is expected in the near future. Binary coalescence has a large influence on the spins of SBHs, even for mass ratios as extreme as 10:1, and evidence of spin-flips may have been observed.

  6. Massive vector fields and black holes

    International Nuclear Information System (INIS)

    Frolov, V.P.

    1977-04-01

    A massive vector field inside the event horizon created by the static sources located outside the black hole is investigated. It is shown that the back reaction of such a field on the metric near r = 0 cannot be neglected. The possibility of the space-time structure changing near r = 0 due to the external massive field is discussed

  7. Black holes in massive conformal gravity

    International Nuclear Information System (INIS)

    Myung, Yun Soo

    2014-01-01

    We analyze the classical stability of Schwarzschild black hole in massive conformal gravity which was recently proposed for another massive gravity model. This model in the Jordan frame is conformally equivalent to the Einstein–Weyl gravity in the Einstein frame. The coupled linearized Einstein equation is decomposed into the traceless and trace equation when one chooses 6m 2 φ=δR. Solving the traceless equation exhibits unstable modes featuring the Gregory–Laflamme s-mode instability of five-dimensional black string, while we find no unstable modes when solving the trace equation. It is shown that the instability of the black hole in massive conformal gravity arises from the massiveness where the geometry of extra dimension trades for mass.

  8. Are Nuclear Star Clusters the Precursors of Massive Black Holes?

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    Nadine Neumayer

    2012-01-01

    Full Text Available We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 106M⊙, if any. We also derive new upper limits for nuclear star cluster masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following. (1 The MBH-σ relation cannot flatten at low masses, but may steepen. (2 The MBH-Mbulge relation may well flatten in contrast. (3 The MBH-Sersic n relation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in the MBH-Sersic n relation seem to be dwarf elliptical galaxies. When plotting MBH versus MNC we find three different regimes: (a nuclear cluster dominated nuclei, (b a transition region, and (c black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratio MBH/MNC grows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.

  9. The Black Hole Radiation in Massive Gravity

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    Ivan Arraut

    2018-02-01

    Full Text Available We apply the Bogoliubov transformations in order to connect two different vacuums, one located at past infinity and another located at future infinity around a black hole inside the scenario of the nonlinear theory of massive gravity. The presence of the extra degrees of freedom changes the behavior of the logarithmic singularity and, as a consequence, the relation between the two Bogoliubov coefficients. This has an effect on the number of particles, or equivalently, on the black hole temperature perceived by observers defining the time arbitrarily.

  10. Black hole entropy in massive Type IIA

    Science.gov (United States)

    Benini, Francesco; Khachatryan, Hrachya; Milan, Paolo

    2018-02-01

    We study the entropy of static dyonic BPS black holes in AdS4 in 4d N=2 gauged supergravities with vector and hyper multiplets, and how the entropy can be reproduced with a microscopic counting of states in the AdS/CFT dual field theory. We focus on the particular example of BPS black holes in AdS{\\hspace{0pt}}4 × S6 in massive Type IIA, whose dual three-dimensional boundary description is known and simple. To count the states in field theory we employ a supersymmetric topologically twisted index, which can be computed exactly with localization techniques. We find a perfect match at leading order.

  11. Massive Black Hole Implicated in Stellar Destruction

    Science.gov (United States)

    2010-01-01

    New results from NASA's Chandra X-ray Observatory and the Magellan telescopes suggest that a dense stellar remnant has been ripped apart by a black hole a thousand times as massive as the Sun. If confirmed, this discovery would be a cosmic double play: it would be strong evidence for an intermediate mass black hole, which has been a hotly debated topic, and would mark the first time such a black hole has been caught tearing a star apart. This scenario is based on Chandra observations, which revealed an unusually luminous source of X-rays in a dense cluster of old stars, and optical observations that showed a peculiar mix of elements associated with the X-ray emission. Taken together, a case can be made that the X-ray emission is produced by debris from a disrupted white dwarf star that is heated as it falls towards a massive black hole. The optical emission comes from debris further out that is illuminated by these X-rays. The intensity of the X-ray emission places the source in the "ultraluminous X-ray source" or ULX category, meaning that it is more luminous than any known stellar X-ray source, but less luminous than the bright X-ray sources (active galactic nuclei) associated with supermassive black holes in the nuclei of galaxies. The nature of ULXs is a mystery, but one suggestion is that some ULXs are black holes with masses between about a hundred and several thousand times that of the Sun, a range intermediate between stellar-mass black holes and supermassive black holes located in the nuclei of galaxies. This ULX is in a globular cluster, a very old and crowded conglomeration of stars. Astronomers have suspected that globular clusters could contain intermediate-mass black holes, but conclusive evidence for this has been elusive. "Astronomers have made cases for stars being torn apart by supermassive black holes in the centers of galaxies before, but this is the first good evidence for such an event in a globular cluster," said Jimmy Irwin of the University

  12. Supersonic gas streams enhance the formation of massive black holes in the early universe.

    Science.gov (United States)

    Hirano, Shingo; Hosokawa, Takashi; Yoshida, Naoki; Kuiper, Rolf

    2017-09-29

    The origin of super-massive black holes in the early universe remains poorly understood. Gravitational collapse of a massive primordial gas cloud is a promising initial process, but theoretical studies have difficulty growing the black hole fast enough. We report numerical simulations of early black hole formation starting from realistic cosmological conditions. Supersonic gas motions left over from the Big Bang prevent early gas cloud formation until rapid gas condensation is triggered in a protogalactic halo. A protostar is formed in the dense, turbulent gas cloud, and it grows by sporadic mass accretion until it acquires 34,000 solar masses. The massive star ends its life with a catastrophic collapse to leave a black hole-a promising seed for the formation of a monstrous black hole. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  13. 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.

  14. Probing Quiescent Massive Black Holes: Insights from Tidal Disruption Events

    OpenAIRE

    Gezari, Suvi; Strubbe, Linda; Bloom, Joshua S.; Grindlay, J. E.; Soderberg, Alicia; Elvis, Martin; Coppi, Paolo; Lawrence, Andrew; Ivezic, Zeljko; Merritt, David; Komossa, Stefanie; Halpern, Jules; Eracleous, Michael

    2009-01-01

    Tidal disruption events provide a unique probe of quiescent black holes in the nuclei of distant galaxies. The next generation of synoptic surveys will yield a large sample of flares from the tidal disruption of stars by massive black holes that will give insights to four key science questions: 1) What is the assembly history of massive black holes in the universe? 2) Is there a population of intermediate mass black holes that are the primordial seeds of supermassive black holes? 3) How can w...

  15. A Practical Guide to the Massive Black Hole Cosmic History

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    A. Sesana

    2012-01-01

    Full Text Available I review our current understanding of massive black hole (MBH formation and evolution along the cosmic history. After a brief introductory overview of the relevance of MBHs in the hierarchical structure formation paradigm, I discuss the main viable channels for seed BH formation at high redshift and for their subsequent mass growth and spin evolution. The emerging hierarchical picture, where MBHs grow through merger triggered accretion episodes, acquiring their mass while shining as quasars, is overall robust, but too simplistic to explain the diversity observed in MBH phenomenology. I briefly discuss which future observations will help to shed light on the MBH cosmic history in the near future, paying particular attention to the upcoming gravitational wave window.

  16. Black hole conserved charges in Generalized Minimal Massive Gravity

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    M.R. Setare

    2015-05-01

    Full Text Available In this paper we construct mass, angular momentum and entropy of black hole solution of Generalized Minimal Massive Gravity (GMMG in asymptotically Anti-de Sitter (AdS spacetimes. The Generalized Minimal Massive Gravity theory is realized by adding the CS deformation term, the higher derivative deformation term, and an extra term to pure Einstein gravity with a negative cosmological constant. We apply our result for conserved charge Qμ(ξ¯ to the rotating BTZ black hole solution of GMMG, and find energy, angular momentum and entropy. Then we show that our results for these quantities are consistent with the first law of black hole thermodynamics.

  17. Black-hole-regulated star formation in massive galaxies.

    Science.gov (United States)

    Martín-Navarro, Ignacio; Brodie, Jean P; Romanowsky, Aaron J; Ruiz-Lara, Tomás; van de Ven, Glenn

    2018-01-18

    Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

  18. Black-hole-regulated star formation in massive galaxies

    Science.gov (United States)

    Martín-Navarro, Ignacio; Brodie, Jean P.; Romanowsky, Aaron J.; Ruiz-Lara, Tomás; van de Ven, Glenn

    2018-01-01

    Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

  19. MASSIVE BLACK HOLES IN STELLAR SYSTEMS: 'QUIESCENT' ACCRETION AND LUMINOSITY

    International Nuclear Information System (INIS)

    Volonteri, M.; Campbell, D.; Mateo, M.; Dotti, M.

    2011-01-01

    Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus. However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star clusters, to massive galaxies. The mere presence of stars in the vicinity of a black hole provides a source of fuel via mass loss of evolved stars. In this paper, we assess the expected luminosities of black holes embedded in stellar systems of different sizes and properties, spanning a large range of masses. We model the distribution of stars and derive the amount of gas available to a central black hole through a geometrical model. We estimate the luminosity of the black holes under simple, but physically grounded, assumptions on the accretion flow. Finally, we discuss the detectability of 'quiescent' black holes in the local universe.

  20. The Cosmogony of Super-Massive Black Holes

    International Nuclear Information System (INIS)

    Duschl, Wolfgang J; Strittmatter, Peter A

    2012-01-01

    We summarize our recent results on the evolution of super-massive black holes in the cores of galaxies. Our models are based on the viscous, Eddington-limited evolution of self-gravitating accretion disks. We find that, within this framework, one can explain the growth time scales and the luminosities of individual objects as well as the variation of these quantities for AGN with different black hole masses.

  1. Gravitational Rocket from the Merging Massive Black Hole Binaries

    Science.gov (United States)

    Choi, Dale

    2006-01-01

    Coalescing massive black hole binaries are expected to be among the most fascinating gravitational wave sources, observable by the NASA/ESA LISA detector. Not only will the merger events reveal the rich phenomenology of extremely strong and dynamical gravity deep inside the potential wells at the centers of galaxies (thus providing an excellent testing ground for general relativity), it will also make important contributions to the astrophysics of massive black hole evolutions. Typical black hole mergers involve asymmetric radiation of gravitational waves and lose linear momentum as well as energy and angular momentum. As a result, the merger remnant receives a kick from the GW emission: a gravitational rocket effect. High kick velocities (higher than the escape velocities of the host structure) would have a strong impact on our understanding of how massive black holes have evolved over time and, in particular, on the estimates of the merger rate for LISA. The main difficulties in calculations of the kick velocities has been in the last moments of the merger where the full theory of general relativity must be employed to accurately model the black hole dynamics. I describe a recent calculation of the kick velocities from numerical relativity simulations of the merging black hole binaries.

  2. Black string in dRGT massive gravity

    Science.gov (United States)

    Tannukij, Lunchakorn; Wongjun, Pitayuth; Ghosh, Suchant G.

    2017-12-01

    We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This "dRGT black string" can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of black string solution such as the monopole-black string ones since the graviton mass contributes to the global monopole term as well as the cosmological-constant term. To investigate the solution, we compute mass, temperature, and entropy of the dRGT black string. We found that the existence of the graviton mass drastically affects the thermodynamics of the black string. Furthermore, the Hawking-Page phase transition is found to be possible for the dRGT black string as well as the charged dRGT black string. The dRGT black string solution is thermodynamically stable for r>r_c with negative thermodynamical potential and positive heat capacity while it is unstable for r

  3. Black string in dRGT massive gravity

    International Nuclear Information System (INIS)

    Tannukij, Lunchakorn; Wongjun, Pitayuth; Ghosh, Suchant G.

    2017-01-01

    We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This ''dRGT black string'' can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of black string solution such as the monopole-black string ones since the graviton mass contributes to the global monopole term as well as the cosmological-constant term. To investigate the solution, we compute mass, temperature, and entropy of the dRGT black string. We found that the existence of the graviton mass drastically affects the thermodynamics of the black string. Furthermore, the Hawking-Page phase transition is found to be possible for the dRGT black string as well as the charged dRGT black string. The dRGT black string solution is thermodynamically stable for r > r c with negative thermodynamical potential and positive heat capacity while it is unstable for r < r c where the potential is positive. (orig.)

  4. Black string in dRGT massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Tannukij, Lunchakorn [Mahidol University, Department of Physics, Faculty of Science, Bangkok (Thailand); Hanyang University, Department of Physics, Seoul (Korea, Republic of); Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Wongjun, Pitayuth [Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Ministry of Education, Thailand Center of Excellence in Physics, Bangkok (Thailand); Ghosh, Suchant G. [Jamia Millia Islamia, Centre of Theoretical Physics, New Delhi (India); University of Kwazulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Durban (South Africa)

    2017-12-15

    We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This ''dRGT black string'' can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of black string solution such as the monopole-black string ones since the graviton mass contributes to the global monopole term as well as the cosmological-constant term. To investigate the solution, we compute mass, temperature, and entropy of the dRGT black string. We found that the existence of the graviton mass drastically affects the thermodynamics of the black string. Furthermore, the Hawking-Page phase transition is found to be possible for the dRGT black string as well as the charged dRGT black string. The dRGT black string solution is thermodynamically stable for r > r{sub c} with negative thermodynamical potential and positive heat capacity while it is unstable for r < r{sub c} where the potential is positive. (orig.)

  5. Hawking Radiation of Massive Bosons via Tunneling from Black Strings

    Science.gov (United States)

    Feng, Zhong-Wen

    2018-03-01

    In the present paper, the Hawking radiation of massive bosons from 4-dimensional and 5-dimensional black strings are studied in quantum tunneling formalism. First, we derive the Hamilton-Jacobi equation set via the Proca equation and WKB approximation. Then, the tunneling rates and Hawking temperatures of the black strings are obtained. Our calculations show that the tunneling rates and Hawking temperatures are related to the properties of black strings' spacetime. When compare our results with those of scalars and fermions cases, it finds that they are the same.

  6. Stars and singularities: Stellar phenomena near a massive black hole

    OpenAIRE

    Alexander, Tal

    2002-01-01

    This is a pedagogical review of recent results on the interactions of central massive black holes with stars very near them, focused on the black hole in the center of the Milky Way. Table of contents: [1] Introduction [2] Stellar dynamics near a black hole [2.1] Physical scales [2.2] A relaxed stellar system around a MBH [3] The stellar collider in the Galactic Center [3.1] The case for a dense stellar cusp in the Galactic Center [3.2] Tidal spin-up [3.3] Tidal scattering [4] The gravitation...

  7. GROWTH OF MASSIVE BLACK HOLES AT THEIR LATE STAGE

    International Nuclear Information System (INIS)

    Xu Yadi; Cao Xinwu

    2010-01-01

    It is believed that the growth of local massive black holes was dominated by accretion during quasar phases, while a fraction of the local black hole mass was accumulated through accreting gases at very low rates. We derive the black hole mass density as a function of redshift with the bolometric luminosity function of active galactic nuclei (AGNs) assuming that massive black holes grew via accreting the circumnuclear gases, in which the derived black hole mass density is required to match the measured local black hole mass density at z = 0. Advection-dominated accretion flows (ADAFs) are supposed to be present in low-luminosity AGNs/normal galaxies, which are very hot and radiate mostly in the hard X-ray band. Most of the X-ray background (XRB) is contributed by bright AGNs, and a variety of AGN population synthesis models were developed to model the observed XRB in the last two decades. Based on our derived black hole mass density, we calculate the contribution to the XRB from the ADAFs in faint AGNs/normal galaxies with a given Eddington ratio distribution, which is mostly in the hard X-ray energy band with an energy peak at ∼200 keV. The growth of massive black holes during the ADAF phase can therefore be constrained with the observed XRB. Combining an AGN population synthesis model with our results, we find that the fitting on the observed XRB, especially at the hard X-ray energy band with ∼>100 keV, is improved provided the contribution of the ADAFs in low-luminosity AGNs/normal galaxies is properly included. It is found that less than ∼15% of local massive black hole mass density was accreted during ADAF phases. We suggest that more accurate measurements of the XRB in the energy band with ∼>100 keV in the future may help constrain the growth of massive black holes at their late stage. We also calculate their contribution to the extragalactic γ-ray background (EGRB), and find that less than ∼1% of the observed EGRB is contributed by the ADAFs in

  8. The formation and evolution of massive black holes.

    Science.gov (United States)

    Volonteri, M

    2012-08-03

    The past 10 years have witnessed a change of perspective in the way astrophysicists think about massive black holes (MBHs), which are now considered to have a major role in the evolution of galaxies. This appreciation was driven by the realization that black holes of millions of solar masses and above reside in the center of most galaxies, including the Milky Way. MBHs also powered active galactic nuclei known to exist just a few hundred million years after the Big Bang. Here, I summarize the current ideas on the evolution of MBHs through cosmic history, from their formation about 13 billion years ago to their growth within their host galaxies.

  9. Probing Massive Black Hole Populations and Their Environments with LISA

    Science.gov (United States)

    Katz, Michael; Larson, Shane

    2018-01-01

    With the adoption of the LISA Mission Proposal by the European Space Agency in response to its call for L3 mission concepts, gravitational wave measurements from space are on the horizon. With data from the Illustris large-scale cosmological simulation, we provide analysis of LISA detection rates accompanied by characterization of the merging Massive Black Holes (MBH) and their host galaxies. MBHs of total mass $\\sim10^6-10^9 M_\\odot$ are the main focus of this study. Using a precise treatment of the dynamical friction evolutionary process prior to gravitational wave emission, we evolve MBH simulation particle mergers from $\\sim$kpc scales until coalescence to achieve a merger distribution. Using the statistical basis of the Illustris output, we Monte-carlo synthesize many realizations of the merging massive black hole population across space and time. We use those realizations to build mock LISA detection catalogs to understand the impact of LISA mission configurations on our ability to probe massive black hole merger populations and their environments throughout the visible Universe.

  10. The (Super Massive Black Hole)-(Host Bulge) Mass Relation

    Science.gov (United States)

    Graham, Alister

    2012-05-01

    Graham (2012, ApJ, v.746, article 113, "Breaking the law: the Mbh-Mspheroid relation") is presented. The popular, and previously thought to be log-linear, relation between super massive black hole mass, Mbh, and the dynamical mass of the host spheroid, Msph, is reexamined in the context of achieving consistency with established galaxy scaling relations. The Mbh-Msph relation for classical spheroids is found to be bent or curved, in agreement with expectations, and requiring an order of magnitude reduction to the mass ratio at Mbh = 106 MSun, such that Mbh/Msph = 0.025%. This new bent relation has important implications for black hole mass predictions in other galaxies, galaxy/black hole formation theories, evolutionary studies and more.

  11. Fueling-Controlled the Growth of Massive Black Holes

    Science.gov (United States)

    Escala, A.

    2009-05-01

    We study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using AMR numerical simulations, we analyze how gas is transported into the nuclear (central kpc) regions of galaxies. We study gas fueling onto the inner accretion disk (sub-pc scale) and star formation in a massive nuclear disk like those generally found in proto-spheroids (ULIRGs, SCUBA Galaxies). These sub-pc resolution simulations of gas fueling, which is mainly depleted by star formation, naturally satisfy the `M_BH-M_{virial}' relation, with a scatter considerably less than that observed. We find that a generalized version of the Kennicutt-Schmidt Law for starbursts is satisfied, in which the total gas depletion rate (dot M_gas=dot M_BH + M_SF scales as M_gas/t_orbital. See Escala (2007) for more details about this work.

  12. Galaxies Grow Their Bulges and Black Holes in Diverse Ways

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Eric F.; Harmsen, Benjamin; D’Souza, Richard [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109-1107 (United States); Monachesi, Antonela [Max Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1317, D-85741 Garching (Germany); Jong, Roelof S. de [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Bailin, Jeremy [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487-0324 (United States); Radburn-Smith, David J. [Department of Astronomy, University of Washington, 3910 15th Avenue NE, Seattle, WA 98195 (United States); Holwerda, Benne W., E-mail: ericbell@umich.edu [Department of Physics and Astronomy, University of Louisville, 102 Natural Science Building, Louisville, KY 40292 (United States)

    2017-03-01

    Galaxies with Milky Way–like stellar masses have a wide range of bulge and black hole masses; in turn, these correlate with other properties such as star formation history. While many processes may drive bulge formation, major and minor mergers are expected to play a crucial role. Stellar halos offer a novel and robust measurement of galactic merger history; cosmologically motivated models predict that mergers with larger satellites produce more massive, higher-metallicity stellar halos, reproducing the recently observed stellar halo metallicity–mass relation. We quantify the relationship between stellar halo mass and bulge or black hole prominence using a sample of 18 Milky Way-mass galaxies with newly available measurements of (or limits on) stellar halo properties. There is an order of magnitude range in bulge mass, and two orders of magnitude in black hole mass, at a given stellar halo mass (or, equivalently, merger history). Galaxies with low-mass bulges show a wide range of quiet merger histories, implying formation mechanisms that do not require intense merging activity. Galaxies with massive “classical” bulges and central black holes also show a wide range of merger histories. While three of these galaxies have massive stellar halos consistent with a merger origin, two do not—merging appears to have had little impact on making these two massive “classical” bulges. Such galaxies may be ideal laboratories to study massive bulge formation through pathways such as early gas-rich accretion, violent disk instabilities, or misaligned infall of gas throughout cosmic time.

  13. Periodic self-lensing from accreting massive black hole binaries

    Science.gov (United States)

    D'Orazio, Daniel J.; Di Stefano, Rosanne

    2018-03-01

    Nearly 150 massive black hole binary (MBHB) candidates at sub-pc orbital separations have been reported in recent literature. Nevertheless, the definitive detection of even a single such object remains elusive. If at least one of the black holes is accreting, the light emitted from its accretion disc will be lensed by the other black hole for binary orbital inclinations near to the line of sight. This binary self-lensing could provide a unique signature of compact MBHB systems. We show that, for MBHBs with masses in the range 106-1010 M⊙ and with orbital periods less than ˜10 yr, strong lensing events should occur in one to 10s of per cent of MBHB systems that are monitored for an entire orbit. Lensing events will last from days for the less massive, shorter period MBHBs to a year for the most massive ˜10 year orbital period MBHBs. At small inclinations of the binary orbit to the line of sight, lensing must occur and will be accompanied by periodicity due to the relativistic Doppler boost. Flares at the same phase as the otherwise average flux of the Doppler modulation would be a smoking gun signature of self-lensing and can be used to constrain binary parameters. For MBHBs with separation ≳100 Schwarzschild radii, we show that finite-sized source effects could serve as a probe of MBH accretion disc structure. Finally, we stress that our lensing probability estimate implies that ˜10 of the known MBHB candidates identified through quasar periodicity should exhibit strong lensing flares.

  14. Astrophysics of Super-Massive Black Hole Mergers

    Science.gov (United States)

    Schnittman, Jeremy D.

    2013-01-01

    We present here an overview of recent work in the subject of astrophysical manifestations of super-massive black hole (SMBH) mergers. This is a field that has been traditionally driven by theoretical work, but in recent years has also generated a great deal of interest and excitement in the observational astronomy community. In particular, the electromagnetic (EM) counterparts to SMBH mergers provide the means to detect and characterize these highly energetic events at cosmological distances, even in the absence of a space-based gravitational-wave observatory. In addition to providing a mechanism for observing SMBH mergers, EM counterparts also give important information about the environments in which these remarkable events take place, thus teaching us about the mechanisms through which galaxies form and evolve symbiotically with their central black holes.

  15. Star clusters containing massive, central black holes: evolution calculations

    International Nuclear Information System (INIS)

    Marchant, A.B.

    1980-01-01

    This dissertation presents a detailed, two-dimensional simulations of star cluster evolution. A Monte-Carlo method is adapted to simulate the development with time of isolated star clusters. Clusters which evolve on relaxation timescales with and without central black holes are treated. The method is flexible and rugged, rather than highly accurate. It treats the boundary conditions of stellar evaporation and tidal disruption by a central black hole in a precise, stochastic fashion. Dynamical cloning and renormalization and the use of a time-step adjustment algorithm enhance the feasibility of the method which simulates systems with wide ranges of intrinsic length and time scales. First, the method is applied to follow the development and core collapse of an initial Plummer-model cluster without a central black hole. Agreement of these results for early times with the results of previous authors serves as a verification of this method. Three calculations of cluster re-expansion, each beginning with the insertion of a black hole at the center of a highly collapsed cluster core is presented. Each case is characterized by a different value of initial black hole mass or black hole accretion efficiency for the consumption of debris from disrupted stars. It is found that for the special cases examined here substantial, but not catastrophic, growth of the central black hole may accompany core re-expansion. Also, the observability of the evolutionary phases associated with core collapse and re-expansion, constraints on x-ray sources which could be associated with growing black holes, and the observable signature of the cusp of stars surrounding a central black hole are discussed

  16. Tidal capture of stars by a massive black hole

    Science.gov (United States)

    Novikov, I. D.; Pethick, C. J.; Polnarev, A. G.

    1992-01-01

    The processes leading to tidal capture of stars by a massive black hole and the consequences of these processes in a dense stellar cluster are discussed in detail. When the amplitude of a tide and the subsequent oscillations are sufficiently large, the energy deposited in a star after periastron passage and formation of a bound orbit cannot be estimated directly using the linear theory of oscillations of a spherical star, but rather numerical estimates must be used. The evolution of a star after tidal capture is discussed. The maximum ratio R of the cross-section for tidal capture to that for tidal disruption is about 3 for real systems. For the case of a stellar system with an empty capture loss cone, even in the case when the impact parameter for tidal capture only slightly exceeds the impact parameter for direct tidal disruption, tidal capture would be much more important than tidal disruption.

  17. CMB bounds on disk-accreting massive primordial black holes

    Science.gov (United States)

    Poulin, Vivian; Serpico, Pasquale D.; Calore, Francesca; Clesse, Sébastien; Kohri, Kazunori

    2017-10-01

    Stellar-mass primordial black holes (PBH) have been recently reconsidered as a dark matter (DM) candidate after the aLIGO discovery of several binary black hole (BH) mergers with masses of tens of M⊙ . Matter accretion on such massive objects leads to the emission of high-energy photons, capable of altering the ionization and thermal history of the universe. This, in turn, affects the statistical properties of the cosmic microwave background (CMB) anisotropies. Previous analyses have assumed spherical accretion. We argue that this approximation likely breaks down and that an accretion disk should form in the dark ages. Using the most up-to-date tools to compute the energy deposition in the medium, we derive constraints on the fraction of DM in PBH. Provided that disks form early on, even under conservative assumptions for accretion, these constraints exclude a monochromatic distribution of PBH with masses above ˜2 M⊙ as the dominant form of DM. The bound on the median PBH mass gets more stringent if a broad, log-normal mass function is considered. A deepened understanding of nonlinear clustering properties and BH accretion disk physics would permit an improved treatment and possibly lead to more stringent constraints.

  18. The Fate of Massive Black Holes in Gas-Rich Galaxy Mergers

    Science.gov (United States)

    Escala, A.; Larson, R. B.; Coppi, P. S.; Mardones, D.

    2006-06-01

    Using SPH numerical simulations, we investigate the effects of gas on the inspiral and merger of a massive black hole binary. This study is motivated by the very massive nuclear gas disks observed in the central regions of merging galaxies. Here we present results that expand on the treatment in previous works (Escala et al. 2004, 2005), by studying the evolution of a binary with different black holes masses in a massive gas disk.

  19. Formation of massive black holes in galactic nuclei: runaway tidal encounters

    Science.gov (United States)

    Stone, Nicholas C.; Küpper, Andreas H. W.; Ostriker, Jeremiah P.

    2017-06-01

    Nuclear star clusters (NSCs) and supermassive black holes (SMBHs) both inhabit galactic nuclei, coexisting in a range of bulge masses, but excluding each other in the largest or smallest galaxies. We propose that the transformation of NSCs into SMBHs occurs via runaway tidal captures, once NSCs exceed a certain critical central density and velocity dispersion. The bottleneck in this process is growing the first e-fold in black hole mass. The growth of a stellar mass black hole past this bottleneck occurs as tidally captured stars are consumed in repeated episodes of mass transfer at pericentre. Tidal captures may deactivate as a growth channel once the black hole mass ≳102-3 M⊙, but tidal disruption events will continue and can grow the seed SMBH to larger sizes. The runaway slows (becomes subexponential) once the seed SMBH consumes the core of its host NSC. While most of the cosmic mass density in SMBHs is ultimately produced by episodic gaseous accretion in very massive galaxies, the smallest SMBHs have probably grown from strong tidal encounters with NSC stars. SMBH seeds that grow for a time t entirely through this channel will follow simple power-law relations with the velocity dispersion, σ, of their host galaxy. In the simplest regime, it is M_\\bullet ˜ σ ^{3/2}√{M_\\star t / G} ˜ 106 M_{⊙} (σ / 50 {km s}^{-1})^{3/2}(t/10^{10} yr)^{1/2}, but the exponents and pre-factor can differ slightly depending on the details of loss cone refilling. Current tidal disruption event rates predicted from this mechanism are consistent with observations.

  20. ENHANCED TIDAL DISRUPTION RATES FROM MASSIVE BLACK HOLE BINARIES

    International Nuclear Information System (INIS)

    Chen Xian; Liu, F. K.; Madau, Piero; Sesana, Alberto

    2009-01-01

    'Hard' massive black hole (MBH) binaries embedded in steep stellar cusps can shrink via three-body slingshot interactions. We show that this process will inevitably be accompanied by a burst of stellar tidal disruptions, at a rate that can be several orders of magnitude larger than that appropriate for a single MBH. Our numerical scattering experiments reveal that (1) a significant fraction of stars initially bound to the primary hole are scattered into its tidal disruption loss cone by gravitational interactions with the secondary hole, an enhancement effect that is more pronounced for very unequal mass binaries; (2) about 25% (40%) of all strongly interacting stars are tidally disrupted by an MBH binary of mass ratio q = 1/81 (q = 1/243) and eccentricity 0.1; and (3) two mechanisms dominate the fueling of the tidal disruption loss cone, a Kozai nonresonant interaction that causes the secular evolution of the stellar angular momentum in the field of the binary, and the effect of close encounters with the secondary hole that change the stellar orbital parameters in a chaotic way. For a hard MBH binary of 10 7 M sun and mass ratio 10 -2 , embedded in an isothermal stellar cusp of velocity dispersion σ * = 100 km s -1 , the tidal disruption rate can be as large as N-dot * ∼1 yr -1 . This is 4 orders of magnitude higher than estimated for a single MBH fed by two-body relaxation. When applied to the case of a putative intermediate-mass black hole inspiraling onto Sgr A*, our results predict tidal disruption rates N-dot * ∼0.05-0.1 yr -1 .

  1. SECULAR STELLAR DYNAMICS NEAR A MASSIVE BLACK HOLE

    International Nuclear Information System (INIS)

    Madigan, Ann-Marie; Hopman, Clovis; Levin, Yuri

    2011-01-01

    The angular momentum evolution of stars close to massive black holes (MBHs) is driven by secular torques. In contrast to two-body relaxation, where interactions between stars are incoherent, the resulting resonant relaxation (RR) process is characterized by coherence times of hundreds of orbital periods. In this paper, we show that all the statistical properties of RR can be reproduced in an autoregressive moving average (ARMA) model. We use the ARMA model, calibrated with extensive N-body simulations, to analyze the long-term evolution of stellar systems around MBHs with Monte Carlo simulations. We show that for a single-mass system in steady state, a depression is carved out near an MBH as a result of tidal disruptions. Using Galactic center parameters, the extent of the depression is about 0.1 pc, of similar order to but less than the size of the observed 'hole' in the distribution of bright late-type stars. We also find that the velocity vectors of stars around an MBH are locally not isotropic. In a second application, we evolve the highly eccentric orbits that result from the tidal disruption of binary stars, which are considered to be plausible precursors of the 'S-stars' in the Galactic center. We find that RR predicts more highly eccentric (e > 0.9) S-star orbits than have been observed to date.

  2. Star cluster disruption by a massive black hole binary

    Science.gov (United States)

    Bortolas, Elisa; Mapelli, Michela; Spera, Mario

    2018-02-01

    Massive black hole binaries (BHBs) are expected to form as the result of galaxy mergers; they shrink via dynamical friction and stellar scatterings, until gravitational waves (GWs) bring them to the final coalescence. It has been argued that BHBs may stall at a parsec scale and never enter the GW stage if stars are not continuously supplied to the BHB loss cone. Here, we perform several N-body experiments to study the effect of an 8 × 104 M⊙ stellar cluster (SC) infalling on a parsec-scale BHB. We explore different orbital elements for the SC, and we perform runs both with and without accounting for the influence of a rigid stellar cusp (modelled as a rigid Dehnen potential). We find that the semimajor axis of the BHB shrinks by ≳ 10 per cent if the SC is on a nearly radial orbit; the shrinking is more efficient when a Dehnen potential is included and the orbital plane of the SC coincides with that of the BHB. In contrast, if the SC orbit has non-zero angular momentum, only few stars enter the BHB loss cone and the resulting BHB shrinking is negligible. Our results indicate that SC disruption might significantly contribute to the shrinking of a parsec-scale BHB only if the SC approaches the BHB on a nearly radial orbit.

  3. Relativistic Stellar Dynamics Around a Massive Black Hole in Steady State

    OpenAIRE

    Alexander, Tal

    2015-01-01

    I briefly review advances in the understanding and modeling of relativistic stellar dynamics around massive black holes (MBHs) in galactic nuclei, following the inclusion of coherent relaxation and of secular processes in a new formal analytic description of the dynamics.

  4. RECOILING MASSIVE BLACK HOLES IN GAS-RICH GALAXY MERGERS

    International Nuclear Information System (INIS)

    Guedes, Javiera; Madau, Piero; Mayer, Lucio; Callegari, Simone

    2011-01-01

    The asymmetric emission of gravitational waves produced during the coalescence of a massive black hole (MBH) binary imparts a velocity 'kick' to the system that can displace the hole from the center of its host. Here, we study the trajectories and observability of MBHs recoiling in three (one major, two minor) gas-rich galaxy merger remnants that were previously simulated at high resolution, and in which the pairing of the MBHs had been shown to be successful. We run new simulations of MBHs recoiling in the major merger remnant with Mach numbers in the range 1≤M≤6 and use simulation data to construct a semi-analytical model for the orbital evolution of MBHs in gas-rich systems. We show the following. (1) In major merger remnants the energy deposited by the moving hole into the rotationally supported, turbulent medium makes a negligible contribution to the thermodynamics of the gas. This contribution becomes significant in minor merger remnants, potentially allowing for an electromagnetic signature of MBH recoil. (2) In major merger remnants, the combination of both deeper central potential well and drag from high-density gas confines even MBHs with kick velocities as high as 1200 km s -1 within 1 kpc from the host's center. (3) Kinematically offset nuclei may be observable for timescales of a few Myr in major merger remnants in the case of recoil velocities in the range 700-1000 km s -1 . (4) In minor merger remnants the effect of gas drag is weaker, and MBHs with recoil speeds in the range 300-600 km s -1 will wander through the host halo for longer timescales. When accounting for the probability distribution of kick velocities, however, we find that the likelihood of observing recoiling MBHs in gas-rich galaxy mergers is very low even in the best-case scenario.

  5. A note on the Cardy formula and black holes in 3D (massive) bigravity

    International Nuclear Information System (INIS)

    Bañados, Máximo; Pino, Miguel

    2013-01-01

    We study to what extent the Cardy formula is valid in the context of three-dimensional massive gravity (bigravity). Since this theory has local bulk local excitations (a massive graviton) and black holes are not locally AdS, this example provides a non-trivial test of the robustness of the Cardy formula. (paper)

  6. The formation and gravitational-wave detection of massive stellar black hole binaries

    International Nuclear Information System (INIS)

    Belczynski, Krzysztof; Walczak, Marek; Buonanno, Alessandra; Cantiello, Matteo; Fryer, Chris L.; Holz, Daniel E.; Mandel, Ilya; Miller, M. Coleman

    2014-01-01

    If binaries consisting of two ∼100 M ☉ black holes exist, they would serve as extraordinarily powerful gravitational-wave sources, detectable to redshifts of z ∼ 2 with the advanced LIGO/Virgo ground-based detectors. Large uncertainties about the evolution of massive stars preclude definitive rate predictions for mergers of these massive black holes. We show that rates as high as hundreds of detections per year, or as low as no detections whatsoever, are both possible. It was thought that the only way to produce these massive binaries was via dynamical interactions in dense stellar systems. This view has been challenged by the recent discovery of several ≳ 150 M ☉ stars in the R136 region of the Large Magellanic Cloud. Current models predict that when stars of this mass leave the main sequence, their expansion is insufficient to allow common envelope evolution to efficiently reduce the orbital separation. The resulting black hole-black hole binary remains too wide to be able to coalesce within a Hubble time. If this assessment is correct, isolated very massive binaries do not evolve to be gravitational-wave sources. However, other formation channels exist. For example, the high multiplicity of massive stars, and their common formation in relatively dense stellar associations, opens up dynamical channels for massive black hole mergers (e.g., via Kozai cycles or repeated binary-single interactions). We identify key physical factors that shape the population of very massive black hole-black hole binaries. Advanced gravitational-wave detectors will provide important constraints on the formation and evolution of very massive stars.

  7. Dirac quasinormal modes of new type black holes in new massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2014-07-15

    We study a new type of black holes in three-dimensional new massive gravity and we calculate analytically the quasinormal modes for fermionic perturbations for some special cases. Then we show that for these cases black holes of the new type are stable under fermionic field perturbations. (orig.)

  8. Charged scalar perturbations on charged black holes in de Rham-Gabadadze-Tolley massive gravity

    Science.gov (United States)

    Burikham, Piyabut; Ponglertsakul, Supakchai; Tannukij, Lunchakorn

    2017-12-01

    We explore the quasistationary profile of a massive charged scalar field in a class of charged black holes in de Rham-Gabadadze-Tolley (dRGT) massive gravity. We discuss how the linear term in the metric, which is a unique character of the dRGT massive gravity, affects the structure of the spacetime. Numerical calculations of the quasinormal modes are performed for a charged scalar field in the dRGT black hole background. For an asymptotically de Sitter (dS) black hole, an improved asymptotic iteration method is used to obtain the associated quasinormal frequencies. The unstable modes are found for the ℓ=0 case, and their corresponding real parts satisfy the superradiant condition. For ℓ=2 , the results show that all the de Sitter black holes considered here are stable against a small perturbation. For an asymptotically dRGT anti-de Sitter (AdS) black hole, unstable modes are found with the frequency satisfying the superradiant condition. Effects of massive-gravity parameters are discussed. Analytic calculation reveals the unique diffusive nature of quasinormal modes in the massive-gravity model with the linear term. Numerical results confirm the existence of the characteristic diffusive modes in both the dS and AdS cases.

  9. Thermodynamic properties of massive dilaton black holes II

    OpenAIRE

    Tamaki, Takashi

    2002-01-01

    We numerically reanalyze static and spherically symmetric black hole solutions in an Einstein-Maxwell-dilaton system with a dilaton potential $m_{d}^{2}\\phi^{2}$. We investigate thermodynamic properties for various dilaton coupling constants and find that thermodynamic properties change at a critical dilaton mass $m_{d,crit}$. For $m_{d}\\geq m_{d,crit}$, the black hole becomes an extreme solution for a nonzero horizon radius $r_{h,ex}$ as the Reissner-Nordstr\\"om black hole. However, if $m_{d...

  10. Lifshitz black branes and DC transport coefficients in massive Einstein-Maxwell-dilaton gravity

    Science.gov (United States)

    Kuang, Xiao-Mei; Papantonopoulos, Eleftherios; Wu, Jian-Pin; Zhou, Zhenhua

    2018-03-01

    We construct analytical Lifshitz massive black brane solutions in massive Einstein-Maxwell-dilaton gravity theory. We also study the thermodynamics of these black brane solutions and obtain the thermodynamical stability conditions. On the dual nonrelativistic boundary field theory with Lifshitz symmetry, we analytically compute the DC transport coefficients, including the electric conductivity, thermoelectric conductivity, and thermal conductivity. The novel property of our model is that the massive term supports the Lifshitz black brane solutions with z ≠1 in such a way that the DC transport coefficients in the dual field theory are finite. We also find that the Wiedemann-Franz law in this dual boundary field theory is violated, which indicates that it may involve strong interactions.

  11. Massive vector particles tunneling from Kerr and Kerr–Newman black holes

    Directory of Open Access Journals (Sweden)

    Xiang-Qian Li

    2015-12-01

    Full Text Available In this paper, we investigate the Hawking radiation of massive spin-1 particles from 4-dimensional Kerr and Kerr–Newman black holes. By applying the Hamilton–Jacobi ansatz and the WKB approximation to the field equations of the massive bosons in Kerr and Kerr–Newman space-time, the quantum tunneling method is successfully implemented. As a result, we obtain the tunneling rate of the emitted vector particles and recover the standard Hawking temperature of both the two black holes.

  12. High Energy Activity of the Super-Massive Black Hole at the Galactic Center

    OpenAIRE

    Goldwurm, Andrea

    2007-01-01

    The centre of our galaxy hosts the nearest super-massive black hole to the solar system, identified to the compact radio source Sgr A*. High energy experiments have tried in the past to detect the X/gamma-ray emission expected from the accretion of the surrounding material into this super-massive black hole. Only recently however, thanks to the new generation of telescopes, it has been possible to reveal high energy radiation associated with Sgr A* or its close environment. I will review and ...

  13. An unusually massive stellar black hole in the Galaxy.

    Science.gov (United States)

    Greiner, J; Cuby, J G; McCaughrean, M J

    2001-11-29

    The X-ray source known as GRS1915+105 belongs to a group dubbed 'microquasars'. These objects are binary systems which sporadically eject matter at speeds that appear superluminal, as is the case for some quasars. GRS1915+105 is also one of only two known binary sources thought to contain a maximally spinning black hole. Determining the basic parameters of GRS195+105, such as the masses of the components, will help us to understand jet formation in this system, as well as providing links to other objects which exhibit jets. Using X-ray data, indirect methods have previously been used to infer a variety of masses for the accreting compact object in the range 10-30 solar masses (M middle dot in circle). Here we report a direct measurement of the orbital period and mass function of GRS1915+105, which allow us to deduce a mass of 14 +/- 4 M middle dot in circle for the black hole. Black holes with masses >5-7 M middle dot in circle challenge the conventional picture of black-hole formation in binary systems. Based on the mass estimate, we interpret the distinct X-ray variability of GRS1915+105 as arising from instabilities in an accretion disk that is dominated by radiation pressure, and radiating near the Eddington limit (the point where radiation pressure supports matter against gravity). Also, the mass estimate constrains most models which relate observable X-ray properties to the spin of black holes in microquasars.

  14. Analytical study of a Kerr-Sen black hole and a charged massive scalar field

    Science.gov (United States)

    Bernard, Canisius

    2017-11-01

    It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass M ≫μ regime, where M is the mass of the black hole, and μ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ωI/(ωR-ωc) , where ωI and ωR are, respectively, the imaginary and real parts of the frequency of the modes, and ωc is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016), 10.1103/PhysRevD.94.044036] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979), 10.1016/0003-4916(79)90237-9] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.

  15. No hair for spherically symmetric neutral black holes: Nonminimally coupled massive scalar fields

    Science.gov (United States)

    Hod, Shahar

    2017-12-01

    It is proved that spherically symmetric asymptotically flat neutral black holes cannot support spatially regular static configurations made of massive scalar fields with nonminimal coupling to gravity. Interestingly, our compact no-hair theorem is valid for generic values of the dimensionless physical parameter ξ which quantifies the strength of coupling between the scalar field and the spacetime curvature.

  16. Massive Black Hole Mergers: Can We "See" what LISA will "Hear"?

    Science.gov (United States)

    Centrella, Joan

    2010-01-01

    The final merger of massive black holes produces strong gravitational radiation that can be detected by the space-borne LISA. If the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We will review current efforts to simulate these systems, and discuss possibilities for observing the electromagnetic signals they produce.

  17. Massively parallel red-black algorithms for x-y-z response matrix equations

    International Nuclear Information System (INIS)

    Hanebutte, U.R.; Laurin-Kovitz, K.; Lewis, E.E.

    1992-01-01

    Recently, both discrete ordinates and spherical harmonic (S n and P n ) methods have been cast in the form of response matrices. In x-y geometry, massively parallel algorithms have been developed to solve the resulting response matrix equations on the Connection Machine family of parallel computers, the CM-2, CM-200, and CM-5. These algorithms utilize two-cycle iteration on a red-black checkerboard. In this work we examine the use of massively parallel red-black algorithms to solve response matric equations in three dimensions. This longer term objective is to utilize massively parallel algorithms to solve S n and/or P n response matrix problems. In this exploratory examination, however, we consider the simple 6 x 6 response matrices that are derivable from fine-mesh diffusion approximations in three dimensions

  18. An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10.

    Science.gov (United States)

    Reines, Amy E; Sivakoff, Gregory R; Johnson, Kelsey E; Brogan, Crystal L

    2011-02-03

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  19. A class of black holes in dRGT massive gravity and their thermodynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Suchant G. [Jamia Millia Islamia, Centre of Theoretical Physics, New Delhi (India); University of Kwazulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Private Bag 54001, Durban (South Africa); Tannukij, Lunchakorn [Mahidol University, Department of Physics, Faculty of Science, Bangkok (Thailand); Wongjun, Pitayuth [Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Ministry of Education, Thailand Center of Excellence in Physics, Bangkok (Thailand)

    2016-03-15

    We present an exact spherical black hole solution in de Rham, Gabadadze, and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature and entropy of the dRGT black hole, and also perform thermodynamical stability analysis. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit m{sub g} → 0, reduced exactly to the results of general relativity. (orig.)

  20. A class of black holes in dRGT massive gravity and their thermodynamical properties

    International Nuclear Information System (INIS)

    Ghosh, Suchant G.; Tannukij, Lunchakorn; Wongjun, Pitayuth

    2016-01-01

    We present an exact spherical black hole solution in de Rham, Gabadadze, and Tolley (dRGT) massive gravity for a generic choice of the parameters in the theory, and also discuss the thermodynamical and phase structure of the black hole in both the grand canonical and the canonical ensembles (for the charged case). It turns out that the dRGT black hole solution includes other known solutions to the Einstein field equations, such as the monopole-de Sitter-Schwarzschild solution with the coefficients of the third and fourth terms in the potential and the graviton mass in massive gravity naturally generates the cosmological constant and the global monopole term. Furthermore, we compute the mass, temperature and entropy of the dRGT black hole, and also perform thermodynamical stability analysis. It turns out that the presence of the graviton mass completely changes the black hole thermodynamics, and it can provide the Hawking-Page phase transition which also occurs for the charged black holes. Interestingly, the entropy of a black hole is barely affected and still obeys the standard area law. In particular, our results, in the limit m g → 0, reduced exactly to the results of general relativity. (orig.)

  1. Dusty Feedback from Massive Black Holes in Two Elliptical Galaxies

    Science.gov (United States)

    Temi, P.; Brighenti, F.; Mathews, W. G.; Amblard, A.; Riguccini, L.

    2013-01-01

    Far-infrared dust emission from elliptical galaxies informs us about galaxy mergers, feedback energy outbursts from supermassive black holes and the age of galactic stars. We report on the role of AGN feedback observationally by looking for its signatures in elliptical galaxies at recent epochs in the nearby universe. We present Herschel observations of two elliptical galaxies with strong and spatially extended FIR emission from colder grains 5-10 kpc distant from the galaxy cores. Extended excess cold dust emission is interpreted as evidence of recent feedback-generated AGN energy outbursts in these galaxies, visible only in the FIR, from buoyant gaseous outflows from the galaxy cores.

  2. Massive vector particles tunneling from black holes influenced by the generalized uncertainty principle

    Directory of Open Access Journals (Sweden)

    Xiang-Qian Li

    2016-12-01

    Full Text Available This study considers the generalized uncertainty principle, which incorporates the central idea of large extra dimensions, to investigate the processes involved when massive spin-1 particles tunnel from Reissner–Nordstrom and Kerr black holes under the effects of quantum gravity. For the black hole, the quantum gravity correction decelerates the increase in temperature. Up to O(1Mf2, the corrected temperatures are affected by the mass and angular momentum of the emitted vector bosons. In addition, the temperature of the Kerr black hole becomes uneven due to rotation. When the mass of the black hole approaches the order of the higher dimensional Planck mass Mf, it stops radiating and yields a black hole remnant.

  3. Superradiant Instability and Backreaction of Massive Vector Fields around Kerr Black Holes.

    Science.gov (United States)

    East, William E; Pretorius, Frans

    2017-07-28

    We study the growth and saturation of the superradiant instability of a complex, massive vector (Proca) field as it extracts energy and angular momentum from a spinning black hole, using numerical solutions of the full Einstein-Proca equations. We concentrate on a rapidly spinning black hole (a=0.99) and the dominant m=1 azimuthal mode of the Proca field, with real and imaginary components of the field chosen to yield an axisymmetric stress-energy tensor and, hence, spacetime. We find that in excess of 9% of the black hole's mass can be transferred into the field. In all cases studied, the superradiant instability smoothly saturates when the black hole's horizon frequency decreases to match the frequency of the Proca cloud that spontaneously forms around the black hole.

  4. Floating and sinking: the imprint of massive scalars around rotating black holes.

    Science.gov (United States)

    Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo

    2011-12-09

    We study the coupling of massive scalar fields to matter in orbit around rotating black holes. It is generally expected that orbiting bodies will lose energy in gravitational waves, slowly inspiraling into the black hole. Instead, we show that the coupling of the field to matter leads to a surprising effect: because of superradiance, matter can hover into "floating orbits" for which the net gravitational energy loss at infinity is entirely provided by the black hole's rotational energy. Orbiting bodies remain floating until they extract sufficient angular momentum from the black hole, or until perturbations or nonlinear effects disrupt the orbit. For slowly rotating and nonrotating black holes floating orbits are unlikely to exist, but resonances at orbital frequencies corresponding to quasibound states of the scalar field can speed up the inspiral, so that the orbiting body sinks. These effects could be a smoking gun of deviations from general relativity.

  5. New perspective for black hole thermodynamics in Gauss-Bonnet-Born-Infeld massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Hendi, Seyed Hossein [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM),Maragha (Iran, Islamic Republic of); Li, Gu-Qiang; Mo, Jie-Xiong [Lingnan Normal University, Institute of Theoretical Physics, Zhanjiang, Guangdong (China); Panahiyan, Shahram [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Panah, Behzad Eslam [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

    2016-10-15

    Following an earlier study regarding Einstein-Gauss-Bonnet-massive black holes in the presence of a Born-Infeld nonlinear electromagnetic field (Hendi, arXiv:1510.00108, 2016), we study thermodynamical structure and critical behavior of these black holes through various methods in this paper. Geometrical thermodynamics is employed to give a picture regarding the phase transition of these black holes. Next, a new method is used to derive critical pressure and radius of the horizon of these black holes. In addition, Maxwell equal area law is employed to study the Van der Waals like behavior of these black holes. Moreover, the critical exponents are calculated and by using Ehrenfest equations, the type of phase transition is determined. (orig.)

  6. Charged BTZ black holes in the context of massive gravity's rainbow

    Science.gov (United States)

    Hendi, S. H.; Panahiyan, S.; Upadhyay, S.; Eslam Panah, B.

    2017-04-01

    Banados, Teitelboim, and Zanelli (BTZ) black holes are excellent laboratories for studying black hole thermodynamics, which is a bridge between classical general relativity and the quantum nature of gravitation. In addition, three-dimensional gravity could have equipped us for exploring some of the ideas behind the two-dimensional conformal field theory based on the AdS3/CFT2 . Considering the significant interest in these regards, we examine charged BTZ black holes. We consider the system contains massive gravity with energy dependent spacetime to enrich the results. In order to make high curvature (energy) BTZ black holes more realistic, we modify the theory by energy dependent constants. We investigate thermodynamic properties of the solutions by calculating heat capacity and free energy. We also analyze thermal stability and study the possibility of the Hawking-Page phase transition. At last, we study the geometrical thermodynamics of these black holes and compare the results of various approaches.

  7. The most massive black holes on the Fundamental Plane of black hole accretion

    Science.gov (United States)

    Mezcua, M.; Hlavacek-Larrondo, J.; Lucey, J. R.; Hogan, M. T.; Edge, A. C.; McNamara, B. R.

    2018-02-01

    We perform a detailed study of the location of brightest cluster galaxies (BCGs) on the Fundamental Plane of black hole (BH) accretion, which is an empirical correlation between a BH X-ray and radio luminosity and mass supported by theoretical models of accretion. The sample comprises 72 BCGs out to z ˜ 0.3 and with reliable nuclear X-ray and radio luminosities. These are found to correlate as L_X ∝ L_R^{0.75 ± 0.08}, favouring an advection-dominated accretion flow as the origin of the X-ray emission. BCGs are found to be on average offset from the Fundamental Plane such that their BH masses seem to be underestimated by the MBH-MK relation a factor ˜10. The offset is not explained by jet synchrotron cooling and is independent of emission process or amount of cluster gas cooling. Those core-dominated BCGs are found to be more significantly offset than those with weak core radio emission. For BCGs to on average follow the Fundamental Plane, a large fraction ( ˜ 40 per cent) should have BH masses >1010 M⊙ and thus host ultramassive BHs. The local BH-galaxy scaling relations would not hold for these extreme objects. The possible explanations for their formation, either via a two-phase process (the BH formed first, the galaxy grows later) or as descendants of high-z seed BHs, challenge the current paradigm of a synchronized galaxy-BH growth.

  8. An over-massive black hole in the compact lenticular galaxy NGC 1277.

    Science.gov (United States)

    van den Bosch, Remco C E; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L

    2012-11-29

    Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10(11) solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10(10) solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.

  9. Greybody factors of massive charged fermionic fields in a charged two-dimensional dilatonic black hole

    Energy Technology Data Exchange (ETDEWEB)

    Becar, Ramon [Universidad Catolica de Temuco, Departamento de Ciencias Matematicas y Fisicas, Temuco (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica, Facultad de Ciencias, La Serena (Chile)

    2015-02-01

    We study massive charged fermionic perturbations in the background of a charged two-dimensional dilatonic black hole, and we solve the Dirac equation analytically. Then we compute the reflection and transmission coefficients and the absorption cross section for massive charged fermionic fields, and we show that the absorption cross section vanishes at the low- and high-frequency limits. However, there is a range of frequencies where the absorption cross section is not null. Furthermore, we study the effect of the mass and electric charge of the fermionic field over the absorption cross section. (orig.)

  10. The Final Merger of Massive Black Holes: Recoils, Gravitational Waves, and Electromagnetic Signatures

    Science.gov (United States)

    Centrella, Joan M.

    2010-01-01

    The final merger of two massive black holes produces a powerful burst of gravitational radiation, emitting more energy than all the stars in the observable universe combined. The resulting gravitational waveforms will be easily detectable by the space-based LISA out to redshifts z greater than 10, revealing the masses and spins of the black holes to high precision. If the merging black holes have unequal masses, or asymmetric spins, the final black hole that forms can recoil with a velocity exceeding 1000 km/s. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new results that are revealing the dynamics and waveforms of binary black hole mergers, recoil velocities, and the possibility of accompanying electromagnetic outbursts.

  11. Massive Black Hole Mergers: Can we see what LISA will hear?

    Science.gov (United States)

    Centrella, Joan

    2009-01-01

    Coalescing massive black hole binaries are formed when galaxies merge. The final stages of this coalescence produce strong gravitational wave signals that can be detected by the space-borne LISA. When the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a first step towards this problem by mapping the flow of pressureless matter in the dynamic, 3-D general relativistic spacetime around the merging black holes. We report on the results of these initial simulations and discuss their likely importance for future hydrodynamical simulations.

  12. Early Growth and Efficient Accretion of Massive Black Holes at High Redshift

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2003-01-01

    Black-hole masses of the highest redshift quasars (4 ~ 4 quasars are very massive (>~ 10^9 solar masses). It is argued that the mass estimates of the high-z quasars are not subject to larger uncertainties than those for nearby quasars. Specifically, the large masses are not overestimates and the ......Black-hole masses of the highest redshift quasars (4 ~ 4 quasars are very massive (>~ 10^9 solar masses). It is argued that the mass estimates of the high-z quasars are not subject to larger uncertainties than those for nearby quasars. Specifically, the large masses are not overestimates...... and the lack of similarly large black-hole masses in the nearby Universe does not rule out their existence at high-z. However, AGN host galaxies do not typically appear fully formed or evolved at these early epochs. This supports scenarios in which black holes build up mass very fast in a radiatively...... inefficient (or obscured) phase relative to the stars in their galaxies. Additionally, upper envelopes of black-hole mass of approximately 10^{10} solar masses and bolometric luminosity of ~ 10^{48} erg/s are observed at all redshifts....

  13. The effects of massive graviton on the equilibrium between the black hole and radiation gas in an isolated box

    Directory of Open Access Journals (Sweden)

    Ya-Peng Hu

    2017-09-01

    Full Text Available It is well known that the black hole can have temperature and radiate the particles with black body spectrum, i.e. Hawking radiation. Therefore, if the black hole is surrounded by an isolated box, there is a thermal equilibrium between the black hole and radiation gas. A simple case considering the thermal equilibrium between the Schwarzschild black hole and radiation gas in an isolated box has been well investigated previously in detail, i.e. taking the conservation of energy and principle of maximal entropy for the isolated system into account. In this paper, following the above spirit, the effects of massive graviton on the thermal equilibrium will be investigated. For the gravity with massive graviton, we will use the de Rham–Gabadadze–Tolley (dRGT massive gravity which has been proven to be ghost free. Because the graviton mass depends on two parameters in the dRGT massive gravity, here we just investigate two simple cases related to the two parameters, respectively. Our results show that in the first case the massive graviton can suppress or increase the condensation of black hole in the radiation gas although the T–E diagram is similar as the Schwarzschild black hole case. For the second case, a new T–E diagram has been obtained. Moreover, an interesting and important prediction is that the condensation of black hole just increases from the zero radius of horizon in this case, which is very different from the Schwarzschild black hole case.

  14. Dynamics of massive black holes as a possible candidate for galactic dark matter.

    Science.gov (United States)

    Xu, Guohong; Ostriker, J. P.

    If the dark halo of the Galaxy is comprised of massive black holes (MBH), then those within approximately 1 kpc will spiral into the center, where they will interact with one another forming binaries which contract due to further dynamical friction and then possibly merge to form more massive objects by emission of gravitational radiation. Several authors have proposed the formation of a very massive galactic nucleus of 108Msun through mergers. This is excluded on observational grounds, since the observed limit for a Galactic central black hole is approximately 106.5Msun. The authors perform detailed N-body calculations using a modified Aarseth code to explore the situation in detail and find that for a "best estimate" model of the Galaxy a runaway does not occur. Instead three body interactions between hard binaries and single MBHs eject massive objects before accumulation of more than a few units, so that typically the center will contain zero, one or two MBHs. The authors study how the situation depends in detail on the mass per MBH, the rotation of the halo, the mass distribution within the Galaxy and other parameters.

  15. Complexity growth rates for AdS black holes in massive gravity and f(R) gravity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wen-Di; Wei, Shao-Wen; Li, Yan-Yan; Liu, Yu-Xiao [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China)

    2017-12-15

    The ''complexity = action'' duality states that the quantum complexity is equal to the action of the stationary AdS black hole within the Wheeler-DeWitt patch at late time approximation. We compute the action growth rates of the neutral and charged black holes in massive gravity and the neutral, charged and Kerr-Newman black holes in f(R) gravity to test this conjecture. Besides, we investigate the effects of the massive graviton terms, higher derivative terms and the topology of the black hole horizon on the complexity growth rate. (orig.)

  16. Formation of massive black holes through runaway collisions in dense young star clusters.

    Science.gov (United States)

    Zwart, Simon F Portegies; Baumgardt, Holger; Hut, Piet; Makino, Junichiro; McMillan, Stephen L W

    2004-04-15

    A luminous X-ray source is associated with MGG 11--a cluster of young stars approximately 200 pc from the centre of the starburst galaxy M 82 (refs 1, 2). The properties of this source are best explained by invoking a black hole with a mass of at least 350 solar masses (350 M(o)), which is intermediate between stellar-mass and supermassive black holes. A nearby but somewhat more massive cluster (MGG 9) shows no evidence of such an intermediate-mass black hole, raising the issue of just what physical characteristics of the clusters can account for this difference. Here we report numerical simulations of the evolution and motion of stars within the clusters, where stars are allowed to merge with each other. We find that for MGG 11 dynamical friction leads to the massive stars sinking rapidly to the centre of the cluster, where they participate in a runaway collision. This produces a star of 800-3,000 M(o) which ultimately collapses to a black hole of intermediate mass. No such runaway occurs in the cluster MGG 9, because the larger cluster radius leads to a mass segregation timescale a factor of five longer than for MGG 11.

  17. Evidence for a massive stellar black hole in x ray Nova Muscae

    Science.gov (United States)

    Chen, Wan; Gehrels, Neil; Cheng, F. H.

    1992-01-01

    We present evidence that the X-ray Nova Muscae system contains a massive, greater than 10 M solarmass, black hole. A recently measured photometric binary mass function gives the black hole mass for this system as a function of orbital inclination angle. From the spectral redshift and width of the positron annihilation gamma-ray line observed by GRANAT/SIGMA, we find the accretion disk inclination angle to be 22 deg plus or minus 18 deg. Assuming the accretion disk lies in the orbital plane of the system, the black hole mass is found to have a lower limit of 14 M solar mass although statistics are poor. This is supported by spectral modeling of combined optical/UV/x-ray/gamma-ray data and by a new Nova Muscae distance limit we derive of greater than 3 kpc. The large mass for this black hole and the high binary mass ratio it implies (greater than 20) raise a serious challenge to theoretical models of the formation and evolution of massive binaries. The gamma-ray line technique introduced here can give tight constraints on orbital parameters when high-sensitivity line measurements are made by such missions as GRO.

  18. Black Identity and the Grow-Shapiro Study on Trans-racial Adoption

    Science.gov (United States)

    Chimezie, Amuzie

    1976-01-01

    This paper evaluated the Grow-Shapiro study of transracial adoption of black children by white parents and assessed its relevance to the controversy over transracial adoption finding that the study failed to seriously address itself to the question of black identity and its correlates--the crux of the adoption controversy. Some suggestions made…

  19. Black holes in massive close binary systems: observation data and evolutionary state

    International Nuclear Information System (INIS)

    Tutukov, A.V.; Cherepashchuk, A.M.; Moskovskij Gosudarstvennyj Univ.

    1985-01-01

    The modern data on the masses of candidates for black holes in binary systems are summarized. The masses of components of binary systems with probable balck holes are compared with the characteristics of the binary sistems with neutron stars. It is pointed out that, concerning the masses of relativistic components, the separation into two groups takes place: Msub(x) approximately equal to 1.6 M (M is solar mass) (neutron stars) and Msub(x) approximately equal to (10-60) M (black holes candidates). The intermediate cases are presumably abssent. The masses of relativistic objects do not correlate with the masses of optical stars. It is shown that during the mass exchange between the optical star ad the neutron star in a close binary. It is difficult to produce a black hole with the mass exceeding (5-7) M. The suggestion is put forward that massive black holes with M > or approximately 10 M may be formed as a result of the collapse of the core of the stars of ordinary (20-100) M initial mass, due to either the increase of the mass of the core of the presupernova, or to the weakness of the magnetic field. A disagreement by a factor of 10-30 between the observed numbers of black holes pairing with OB stars and with the radiopulsars is pointed out, which may be connected with the ''pairing'' formation of black holes

  20. Black holes in massive close binaries - observational data and evolutionary status

    International Nuclear Information System (INIS)

    Tutukov, A.V.; Cherepashchuk, A.M.; Moskovskii Gosudarstvennyi Universitet, Moscow, USSR)

    1985-01-01

    The available information on the mass of four candidate black holes in X-ray binary systems is summarized; these systems are compared with neutron star binaries with regard to the mass of their components. In mass, the relativistic objects form two distinct groups, neutron stars with masses equal to about 1-2 solar masses and black hole candidates with masses equal to about 10-60 solar masses (there seem to be no intermediate cases), but there is no correlation with the mass of the optical star. Mass exchange between the optical component of a close binary and its neutron star companion would be unlikely to produce a black hole more massive than 5-7 solar masses. Instead, the black holes having masses greater than about 10 solar masses might result from core collapse in stars of initial mass equating 20-100 solar masses through either a rise in the presupernova core mass or weakness of the magnetic field. The (10-30)-fold disparity in the incidence of black holes coupled with OB stars and with radio pulsars could indicate that black holes tend to form in pairs. 36 references

  1. Charged massive particle at rest in the field of a Reissner-Nordstroem black hole

    International Nuclear Information System (INIS)

    Bini, D.; Geralico, A.; Ruffini, R.

    2007-01-01

    The interaction of a Reissner-Nordstroem black hole and a charged massive particle is studied in the framework of perturbation theory. The particle backreaction is taken into account, studying the effect of general static perturbations of the hole following the approach of Zerilli. The solutions of the combined Einstein-Maxwell equations for both perturbed gravitational and electromagnetic fields to first order of the perturbation are exactly reconstructed by summing all multipoles, and are given explicit closed form expressions. The existence of a singularity-free solution of the Einstein-Maxwell system requires that the charge-to-mass ratios of the black hole and of the particle satisfy an equilibrium condition which is in general dependent on the separation between the two bodies. If the black hole is undercritically charged (i.e. its charge-to-mass ratio is less than one), the particle must be overcritically charged, in the sense that the particle must have a charge-to-mass ratio greater than one. If the charge-to-mass ratios of the black hole and of the particle are both equal to one (so that they are both critically charged, or 'extreme'), the equilibrium can exist for any separation distance, and the solution we find coincides with the linearization in the present context of the well-known Majumdar-Papapetrou solution for two extreme Reissner-Nordstroem black holes. In addition to these singularity-free solutions, we also analyze the corresponding solution for the problem of a massive particle at rest near a Schwarzschild black hole, exhibiting a strut singularity on the axis between the two bodies. The relations between our perturbative solutions and the corresponding exact two-body solutions belonging to the Weyl class are also discussed

  2. Super massive black hole in galactic nuclei with tidal disruption of stars

    International Nuclear Information System (INIS)

    Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

    2014-01-01

    Tidal disruption of stars by super massive central black holes from dense star clusters is modeled by high-accuracy direct N-body simulation. The time evolution of the stellar tidal disruption rate, the effect of tidal disruption on the stellar density profile, and, for the first time, the detailed origin of tidally disrupted stars are carefully examined and compared with classic papers in the field. Up to 128k particles are used in simulation to model the star cluster around a super massive black hole, and we use the particle number and the tidal radius of the black hole as free parameters for a scaling analysis. The transition from full to empty loss-cone is analyzed in our data, and the tidal disruption rate scales with the particle number, N, in the expected way for both cases. For the first time in numerical simulations (under certain conditions) we can support the concept of a critical radius of Frank and Rees, which claims that most stars are tidally accreted on highly eccentric orbits originating from regions far outside the tidal radius. Due to the consumption of stars moving on radial orbits, a velocity anisotropy is found inside the cluster. Finally we estimate the real galactic center based on our simulation results and the scaling analysis.

  3. Massive black hole and gas dynamics in galaxy nuclei mergers - I. Numerical implementation

    Science.gov (United States)

    Lupi, Alessandro; Haardt, Francesco; Dotti, Massimo

    2015-01-01

    Numerical effects are known to plague adaptive mesh refinement (AMR) codes when treating massive particles, e.g. representing massive black holes (MBHs). In an evolving background, they can experience strong, spurious perturbations and then follow unphysical orbits. We study by means of numerical simulations the dynamical evolution of a pair MBHs in the rapidly and violently evolving gaseous and stellar background that follows a galaxy major merger. We confirm that spurious numerical effects alter the MBH orbits in AMR simulations, and show that numerical issues are ultimately due to a drop in the spatial resolution during the simulation, drastically reducing the accuracy in the gravitational force computation. We therefore propose a new refinement criterion suited for massive particles, able to solve in a fast and precise way for their orbits in highly dynamical backgrounds. The new refinement criterion we designed enforces the region around each massive particle to remain at the maximum resolution allowed, independently upon the local gas density. Such maximally resolved regions then follow the MBHs along their orbits, and effectively avoids all spurious effects caused by resolution changes. Our suite of high-resolution, AMR hydrodynamic simulations, including different prescriptions for the sub-grid gas physics, shows that the new refinement implementation has the advantage of not altering the physical evolution of the MBHs, accounting for all the non-trivial physical processes taking place in violent dynamical scenarios, such as the final stages of a galaxy major merger.

  4. A SYSTEMATIC SEARCH FOR MASSIVE BLACK HOLE BINARIES IN THE SLOAN DIGITAL SKY SURVEY SPECTROSCOPIC SAMPLE

    International Nuclear Information System (INIS)

    Tsalmantza, P.; Decarli, R.; Hogg, David W.; Dotti, M.

    2011-01-01

    We present the results of a systematic search for massive black hole binaries in the Sloan Digital Sky Survey (SDSS) spectroscopic database. We focus on bound binaries, under the assumption that one of the black holes is active. In this framework, the broad lines associated with the accreting black hole are expected to show systematic velocity shifts with respect to the narrow lines, which trace the rest frame of the galaxy. For a sample of 54,586 quasars and 3929 galaxies at redshifts 0.1 < z < 1.5, we brute-force model each spectrum as a mixture of two quasars at two different redshifts. The spectral model is a data-driven dimensionality reduction of the SDSS quasar spectra based on a matrix factorization. We identified 32 objects with peculiar spectra. Nine of them can be interpreted as black hole binaries. This doubles the number of known black hole binary candidates. We also report on the discovery of a new class of extreme double-peaked emitters with exceptionally broad and faint Balmer lines. For all the interesting sources, we present detailed analysis of the spectra and discuss possible interpretations.

  5. Holographic microstate counting for AdS4 black holes in massive IIA supergravity

    Science.gov (United States)

    Hosseini, Seyed Morteza; Hristov, Kiril; Passias, Achilleas

    2017-10-01

    We derive the Bekenstein-Hawking entropy for a class of BPS black holes in the massive type IIA supergravity background AdS4 × S 6 from a microscopic counting of supersymmetric ground states in a holographically dual field theory. The counting is performed by evaluating the topologically twisted index of three-dimensional N=2 Chern-Simons-matter gauge theories in the large N limit. The I-extremization principle is shown to match the attractor mechanism for the near-horizon geometries constructed in the four-dimensional dyonic N=2 gauged supergravity, that arises as a consistent truncation of massive type IIA supergravity on S 6. In particular, our results prove that the imaginary part of the three-dimensional partition functions plays a crucial rôle in holography.

  6. Reentrant phase transitions of higher-dimensional AdS black holes in dRGT massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Zou, De-Cheng; Yue, Ruihong [Yangzhou University, College of Physical Science and Technology, Yangzhou (China); Zhang, Ming [Xi' an Aeronautical University, Faculty of Science, Xi' an (China)

    2017-04-15

    We study the P-V criticality and phase transition in the extended phase space of anti-de Sitter (AdS) black holes in higher-dimensional de Rham, Gabadadze and Tolley (dRGT) massive gravity, treating the cosmological constant as pressure and the corresponding conjugate quantity is interpreted as thermodynamic volume. Besides the usual small/large black hole phase transitions, the interesting thermodynamic phenomena of reentrant phase transitions (RPTs) are observed for black holes in all d ≥ 6-dimensional spacetime when the coupling coefficients c{sub i}m{sup 2} of massive potential satisfy some certain conditions. (orig.)

  7. Isoperimetric surfaces and area-angular momentum inequality in a rotating black hole in new massive gravity

    Science.gov (United States)

    Aceña, Andrés; López, Ericson; Llerena, Mario

    2018-03-01

    We study the existence and stability of isoperimetric surfaces in a family of rotating black holes in new massive gravity. We show that the stability of such surfaces is determined by the sign of the hair parameter. We use the isoperimetric surfaces to find a geometric inequality between the area and the angular momentum of the black hole, conjecturing geometric inequalities for more general black holes.

  8. Impact of LISA's Low Frequency Sensitivity on Observations of Massive Black Hole Mergers

    Science.gov (United States)

    Baker, J.; Centrella, J.

    2005-01-01

    LISA will be able to detect gravitational waves from inspiralling massive black hole (MBH) binaries out to redshifts z > 10. If the binary masses and luminosity distances can be extracted from the Laser Interferometer Space Antenna (LISA) data stream, this information can be used to reveal the merger history of MBH binaries and their host galaxies in the evolving universe. Since this parameter extraction generally requires that LISA observe the inspiral for a significant fraction of its yearly orbit, carrying out this program requires adequate sensitivity at low frequencies, f 1.

  9. No tension between assembly models of super massive black hole binaries and pulsar observations.

    Science.gov (United States)

    Middleton, Hannah; Chen, Siyuan; Del Pozzo, Walter; Sesana, Alberto; Vecchio, Alberto

    2018-02-08

    Pulsar timing arrays are presently the only means to search for the gravitational wave stochastic background from super massive black hole binary populations, considered to be within the grasp of current or near-future observations. The stringent upper limit from the Parkes Pulsar Timing Array has been interpreted as excluding (>90% confidence) the current paradigm of binary assembly through galaxy mergers and hardening via stellar interaction, suggesting evolution is accelerated or stalled. Using Bayesian hierarchical modelling we consider implications of this upper limit for a range of astrophysical scenarios, without invoking stalling, nor more exotic physical processes. All scenarios are fully consistent with the upper limit, but (weak) bounds on population parameters can be inferred. Recent upward revisions of the black hole-galaxy bulge mass relation are disfavoured at 1.6σ against lighter models. Once sensitivity improves by an order of magnitude, a non-detection will disfavour the most optimistic scenarios at 3.9σ.

  10. Topological charged black holes in massive gravity's rainbow and their thermodynamical analysis through various approaches

    Directory of Open Access Journals (Sweden)

    S.H. Hendi

    2017-06-01

    Full Text Available Violation of Lorentz invariancy in the high energy quantum gravity motivates one to consider an energy dependent spacetime with massive deformation of standard general relativity. In this paper, we take into account an energy dependent metric in the context of a massive gravity model to obtain exact solutions. We investigate the geometry of black hole solutions and also calculate the conserved and thermodynamic quantities, which are fully reproduced by the analysis performed with the standard techniques. After examining the validity of the first law of thermodynamics, we conduct a study regarding the effects of different parameters on thermal stability of the solutions. In addition, we employ the relation between cosmological constant and thermodynamical pressure to study the possibility of phase transition. Interestingly, we will show that for the specific configuration considered in this paper, van der Waals like behavior is observed for different topology. In other words, for flat and hyperbolic horizons, similar to spherical horizon, a second order phase transition and van der Waals like behavior are observed. Furthermore, we use geometrical method to construct phase space and study phase transition and bound points for these black holes. Finally, we obtain critical values in extended phase space through the use of a new method.

  11. Topological charged black holes in massive gravity's rainbow and their thermodynamical analysis through various approaches

    Science.gov (United States)

    Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.

    2017-06-01

    Violation of Lorentz invariancy in the high energy quantum gravity motivates one to consider an energy dependent spacetime with massive deformation of standard general relativity. In this paper, we take into account an energy dependent metric in the context of a massive gravity model to obtain exact solutions. We investigate the geometry of black hole solutions and also calculate the conserved and thermodynamic quantities, which are fully reproduced by the analysis performed with the standard techniques. After examining the validity of the first law of thermodynamics, we conduct a study regarding the effects of different parameters on thermal stability of the solutions. In addition, we employ the relation between cosmological constant and thermodynamical pressure to study the possibility of phase transition. Interestingly, we will show that for the specific configuration considered in this paper, van der Waals like behavior is observed for different topology. In other words, for flat and hyperbolic horizons, similar to spherical horizon, a second order phase transition and van der Waals like behavior are observed. Furthermore, we use geometrical method to construct phase space and study phase transition and bound points for these black holes. Finally, we obtain critical values in extended phase space through the use of a new method.

  12. Super-Eddington accreting massive black holes as long-lived cosmological standards.

    Science.gov (United States)

    Wang, Jian-Min; Du, Pu; Valls-Gabaud, David; Hu, Chen; Netzer, Hagai

    2013-02-22

    Super-Eddington accreting massive black holes (SEAMBHs) reach saturated luminosities above a certain accretion rate due to photon trapping and advection in slim accretion disks. We show that these SEAMBHs could provide a new tool for estimating cosmological distances if they are properly identified by hard x-ray observations, in particular by the slope of their 2-10 keV continuum. To verify this idea we obtained black hole mass estimates and x-ray data for a sample of 60 narrow line Seyfert 1 galaxies that we consider to be the most promising SEAMBH candidates. We demonstrate that the distances derived by the new method for the objects in the sample get closer to the standard luminosity distances as the hard x-ray continuum gets steeper. The results allow us to analyze the requirements for using the method in future samples of active black holes and to demonstrate that the expected uncertainty, given large enough samples, can make them into a useful, new cosmological ruler.

  13. Dynamics of massive black holes as a possible candidate of Galactic dark matter

    Science.gov (United States)

    Xu, Guohong; Ostriker, Jeremiah P.

    1994-01-01

    If the dark halo of the Galaxy is comprised of massive black holes (MBHs), then those within approximately 1 kpc will spiral to the center, where they will interact with one another, forming binaries which contract, owing to further dynamical friction, and then possibly merge to become more massive objects by emission of gravitational radiation. If successive mergers would invariably lead, as has been proposed by various authors, to the formation of a very massive nucleus of 10(exp 8) solar mass, then the idea of MBHs as a dark matter candidate could be excluded on observational grounds, since the observed limit (or value) for a Galactic central black hole is approximately 10(exp 6.5) solar mass. But, if successive mergers are delayed or prevented by other processes, such as the gravitational slingshot or rocket effect of gravitational radiation, then a large mass accumulation will not occur. In order to resolve this issue, we perform detailed N-body simulations using a modfied Aarseth code to explore the dynamical behavior of the MBHs, and we find that for a 'best estimate' model of the Galaxy a runaway does not occur. The code treates the MBHs as subject to the primary gravitational forces of one another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to dynamical friction and gravitational radiation. Instead of a runaway, three-body interactions between hard binaries and single MBHs eject massive objects before accumulation of more than a few units, so that typically the center will contain zero, one, or two MBHs. We study how the situation depends in detail on the mass per MBH, the rotation of the halo, the mass distribution within the Galaxy, and other parameters. A runaway will most sensitively depend on the ratio of initial (spheroid/halo) central mass densities and secondarily on the typical values

  14. Thermodynamical structure of AdS black holes in massive gravity with stringy gauge-gravity corrections

    Science.gov (United States)

    Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.

    2016-12-01

    Motivated by gauge/gravity group in the low energy effective theory of the heterotic string theory and novel aspects of massive gravity in the context of lattice physics, the minimal coupling of Gauss-Bonnet-massive gravity with Born-Infeld electrodynamics is considered. At first, the metric function is calculated and then the geometrical properties of the solutions are investigated. It is found that there is an essential singularity at the origin and the intrinsic curvature is regular elsewhere. In addition, the effects of massive parameters are studied and black hole solutions with multi horizons are found in this gravity. Also, the conserved and thermodynamic quantities are calculated, and it is shown that the solutions satisfy the first law of thermodynamics. Furthermore, using heat capacity of these black holes, thermal stability and phase transitions are investigated. The variation of different parameters and related modifications on the (number of) phase transition are examined. Next, the critical behavior of the Gauss-Bonnet-Born-Infeld-massive black holes in the context of extended phase space is studied. It is shown how the variation of the different parameters affects the existence and absence of phase transition. Also, it is found that for specific values of different parameters, these black holes may enjoy the existence of a new type of phase transition which to our knowledge was not observed in black hole physics before.

  15. Can a primordial black hole or wormhole grow as fast as the universe?

    International Nuclear Information System (INIS)

    Carr, B J; Harada, Tomohiro; Maeda, Hideki

    2010-01-01

    This review addresses the issue of whether there are physically realistic self-similar solutions in which a primordial black hole is attached to an exact or asymptotically Friedmann model for an equation of state of the form p = (γ - 1)ρc 2 . In the positive-pressure case (1 < γ < 2), there is no solution in which the black hole is attached to an exact Friedmann background via a sonic point. However, there is a one-parameter family of black hole solutions which are everywhere supersonic and asymptotically quasi-Friedmann, in the sense that they contain a solid angle deficit at large distances. Such solutions exist providing the ratio of the black hole size to the cosmological horizon size is above some critical value and they include 'universal' black holes with an apparent horizon but no event horizon. In the stiff case (γ = 2), there is no self-similar solution in an exact background unless the matter turns into null dust before entering the event horizon; otherwise the only black hole solutions are probably asymptotically quasi-Friedmann universal ones. For a dark-energy-dominated universe (0 < γ < 2/3), there is a one-parameter family of black hole solutions which are properly asymptotically Friedmann (i.e. with no angle deficit) and the ratio of the black hole size to the cosmological horizon size is below some critical value. Above this value, one finds a self-similar cosmological wormhole solution which connects two asymptotic regions: one exactly Friedmann and the other asymptotically quasi-Friedmann. We also consider the possibility of self-similar black hole solutions in a universe dominated by a scalar field. This is like the stiff fluid case if the field is massless, but the situation is less clear if the scalar field is rolling down a potential and therefore massive, as in the quintessence scenario. Although no explicit asymptotically Friedmann black hole solutions of this kind are known, they may exist if the black hole is not too large. (brief

  16. Measuring Parameters of Massive Black Hole Binaries with Partially-Aligned Spins

    Science.gov (United States)

    Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

    2010-01-01

    It is important to understand how well the gravitational-wave observatory LISA can measure parameters of massive black hole binaries. It has been shown that including spin precession in the waveform breaks degeneracies and produces smaller expected parameter errors than a simpler, precession-free analysis. However, recent work has shown that gas in binaries can partially align the spins with the orbital angular momentum, thus reducing the precession effect. We show how this degrades the earlier results, producing more pessimistic errors in gaseous mergers. However, we then add higher harmonics to the signal model; these also break degeneracies, but they are not affected by the presence of gas. The harmonics often restore the errors in partially-aligned binaries to the same as, or better than/ those that are obtained for fully precessing binaries with no harmonics. Finally, we investigate what LISA measurements of spin alignment can tell us about the nature of gas around a binary,

  17. Response of the Black Sea methane budget to massive short-term submarine inputs of methane

    DEFF Research Database (Denmark)

    Schmale, O.; Haeckel, M.; McGinnis, D. F.

    2011-01-01

    A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr(-1). The model predicts that the input of methane is largest at water depths between 600 and 700 m (7......% of the total input), suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e. g. through eruptions of deep......-water mud volcanoes or submarine landslides at intermediate water depths) on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption...

  18. Signature of a Newborn Black Hole from the Collapse of a Supra-massive Millisecond Magnetar

    Science.gov (United States)

    Chen, Wei; Xie, Wei; Lei, Wei-Hua; Zou, Yuan-Chuan; Lü, Hou-Jun; Liang, En-Wei; Gao, He; Wang, Ding-Xiong

    2017-11-01

    An X-ray plateau followed by a steep decay (“internal plateau”) has been observed in both long and short gamma-ray burst (GRBs), implying that a millisecond magnetar operates in some GRBs. The sharp decay at the end of the plateau, marking the abrupt cessation of the magnetar’s central engine, has been considered the collapse of a supra-massive magnetar into a black hole (BH) when it spins down. If this “internal plateau” is indeed evidence of a magnetar central engine, the natural expectation in some candidates would be a signature from the newborn BH. In this work, we find that GRB 070110 is a particular case which shows a small X-ray bump following its “internal plateau.” We interpret the plateau as a spin-down supra-massive magnetar and the X-ray bump as fallback BH accretion. This indicates that a newborn BH is likely active in some GRBs. Therefore, GRB 070110-like events may provide further support to the magnetar central engine model and enable us to investigate the properties of the magnetar as well as the newborn BH.

  19. Massive disc formation in the tidal disruption of a neutron star by a nearly extremal black hole

    International Nuclear Information System (INIS)

    Lovelace, Geoffrey; Kidder, Lawrence E; Duez, Matthew D; Foucart, Francois; Pfeiffer, Harald P; Scheel, Mark A; Szilágyi, Béla

    2013-01-01

    Black hole–neutron star (BHNS) binaries are important sources of gravitational waves for second-generation interferometers, and BHNS mergers are also a proposed engine for short, hard gamma-ray bursts. The behavior of both the spacetime (and thus the emitted gravitational waves) and the neutron-star matter in a BHNS merger depend strongly and nonlinearly on the black hole's spin. While there is a significant possibility that astrophysical black holes could have spins that are nearly extremal (i.e. near the theoretical maximum), to date fully relativistic simulations of BHNS binaries have included black-hole spins only up to S/M 2 = 0.9, which corresponds to the black hole having approximately half as much rotational energy as possible, given the black hole's mass. In this paper, we present a new simulation of a BHNS binary with a mass ratio q = 3 and black-hole spin S/M 2 = 0.97, the highest simulated to date. We find that the black hole's large spin leads to the most massive accretion disc and the largest tidal tail outflow of any fully relativistic BHNS simulations to date, even exceeding the results implied by extrapolating results from simulations with lower black-hole spin. The disc appears to be remarkably stable. We also find that the high black-hole spin persists until shortly before the time of merger; afterward, both merger and accretion spin down the black hole. (paper)

  20. RELICS OF GALAXY MERGING: OBSERVATIONAL PREDICTIONS FOR A WANDERING MASSIVE BLACK HOLE AND ACCOMPANYING STAR CLUSTER IN THE HALO OF M31

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Toshihiro [Astronomy Data Center, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Saito, Yuriko [Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588 (Japan); Miki, Yohei; Mori, Masao, E-mail: ts.kawaguti@nao.ac.jp [Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)

    2014-07-01

    Galaxies and massive black holes (BHs) presumably grow via galactic merging events and subsequent BH coalescence. As a case study, we investigate the merging event between the Andromeda galaxy (M31) and a satellite galaxy. We compute the expected observational appearance of the massive BH that was at the center of the satellite galaxy prior to the merger and is currently wandering in the M31 halo. We demonstrate that a radiatively inefficient accretion flow with a bolometric luminosity of a few tens of solar luminosities develops when Hoyle-Lyttleton accretion onto the BH is assumed. We compute the associated broadband spectrum and show that the radio band (observable with EVLA, ALMA, and the Square Kilometre Array) is the best frequency range in which to detect the emission. We also evaluate the mass and the luminosity of the stars bound by the wandering BH and find that such a star cluster is sufficiently luminous that it could correspond to one of the star clusters found by the PAndAS survey. The discovery of a relic massive BH wandering in a galactic halo will provide a direct means of investigating in detail the coevolution of galaxies and BHs. It also means a new population of BHs (off-center massive BHs) and offers targets for clean BH imaging that avoid strong interstellar scattering in the centers of galaxies.

  1. Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-hoon; Wise, John H.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Princeton U., Astrophys. Sci. Dept.; Alvarez, Marcelo A.; /Canadian Inst. Theor. Astrophys.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2011-11-04

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  2. Massive black-hole binary inspirals: results from the LISA parameter estimation taskforce

    Energy Technology Data Exchange (ETDEWEB)

    Arun, K G [LAL, Univ. Paris-Sud, IN2P3/CNRS, Orsay (France); Babak, Stas; Porter, Edward K; Sintes, Alicia M [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Am Muehlenberg 1, D-14476 Golm bei Potsdam (Germany); Berti, Emanuele; Cutler, Curt [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Cornish, Neil [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Gair, Jonathan [Institute of Astronomy, University of Cambridge, Cambridge, CB30HA (United Kingdom); Hughes, Scott A; Lang, Ryan N [Department of Physics and Kavli Institute for Astrophysics and Space Research, MIT, Cambridge, MA 02139 (United States); Iyer, Bala R; Sinha, Siddhartha [Raman Research Institute, Bangalore, 560 080 (India); Mandel, Ilya [Department of Physics and Astronomy, Northwestern Univ., Evanston, IL (United States); Sathyaprakash, Bangalore S; Van Den Broeck, Chris [School of Physics and Astronomy, Cardiff University, 5, The Parade, Cardiff, CF24 3YB (United Kingdom); Trias, Miquel [Departament de Fisica, Universitat de les Illes Balears, Cra. Valldemossa Km. 7.5, E-07122 Palma de Mallorca (Spain); Volonteri, Marta [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2009-05-07

    The LISA Parameter Estimation Taskforce was formed in September 2007 to provide the LISA Project with vetted codes, source distribution models and results related to parameter estimation. The Taskforce's goal is to be able to quickly calculate the impact of any mission design changes on LISA's science capabilities, based on reasonable estimates of the distribution of astrophysical sources in the universe. This paper describes our Taskforce's work on massive black-hole binaries (MBHBs). Given present uncertainties in the formation history of MBHBs, we adopt four different population models, based on (i) whether the initial black-hole seeds are small or large and (ii) whether accretion is efficient or inefficient at spinning up the holes. We compare four largely independent codes for calculating LISA's parameter-estimation capabilities. All codes are based on the Fisher-matrix approximation, but in the past they used somewhat different signal models, source parametrizations and noise curves. We show that once these differences are removed, the four codes give results in extremely close agreement with each other. Using a code that includes both spin precession and higher harmonics in the gravitational-wave signal, we carry out Monte Carlo simulations and determine the number of events that can be detected and accurately localized in our four population models.

  3. Measuring Parameters of Massive Black Hole Binaries with Partially Aligned Spins

    Science.gov (United States)

    Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

    2011-01-01

    The future space-based gravitational wave detector LISA will be able to measure parameters of coalescing massive black hole binaries, often to extremely high accuracy. Previous work has demonstrated that the black hole spins can have a strong impact on the accuracy of parameter measurement. Relativistic spin-induced precession modulates the waveform in a manner which can break degeneracies between parameters, in principle significantly improving how well they are measured. Recent studies have indicated, however, that spin precession may be weak for an important subset of astrophysical binary black holes: those in which the spins are aligned due to interactions with gas. In this paper, we examine how well a binary's parameters can be measured when its spins are partially aligned and compare results using waveforms that include higher post-Newtonian harmonics to those that are truncated at leading quadrupole order. We find that the weakened precession can substantially degrade parameter estimation, particularly for the "extrinsic" parameters sky position and distance. Absent higher harmonics, LISA typically localizes the sky position of a nearly aligned binary about an order of magnitude less accurately than one for which the spin orientations are random. Our knowledge of a source's sky position will thus be worst for the gas-rich systems which are most likely to produce electromagnetic counterparts. Fortunately, higher harmonics of the waveform can make up for this degradation. By including harmonics beyond the quadrupole in our waveform model, we find that the accuracy with which most of the binary's parameters are measured can be substantially improved. In some cases, the improvement is such that they are measured almost as well as when the binary spins are randomly aligned.

  4. Reentrant Phase Transitions and Triple Points of Topological AdS Black Holes in Born-Infeld-Massive Gravity

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2017-01-01

    Full Text Available Motivated by recent developments of black hole thermodynamics in de Rham, Gabadadze, and Tolley (dRGT massive gravity, we study the critical behaviors of topological Anti-de Sitter (AdS black holes in the presence of Born-Infeld nonlinear electrodynamics. Here the cosmological constant appears as a dynamical pressure of the system and its corresponding conjugate quantity is interpreted as thermodynamic volume. This shows that, besides the Van der Waals-like SBH/LBH phase transitions, the so-called reentrant phase transition (RPT appears in four-dimensional space-time when the coupling coefficients cim2 of massive potential and Born-Infeld parameter b satisfy some certain conditions. In addition, we also find the triple critical points and the small/intermediate/large black hole phase transitions for d=5.

  5. Applicability of massively parallel sequencing on monitoring harmful algae at Varna Bay in the Black Sea.

    Science.gov (United States)

    Dzhembekova, Nina; Urusizaki, Shingo; Moncheva, Snejana; Ivanova, Petya; Nagai, Satoshi

    2017-09-01

    In this study the plankton diversity in 13 environmental samples from Varna Bay (in the western Black Sea) was analyzed using massively parallel sequencing (MPS). This preliminary study was undertaken to assess the potential of this technology for future implementation in monitoring programs in the Black Sea. Amplicon sequences of the 18S rRNA gene (V4-5 regions) were obtained using the Illumina MiSeq 250PE platform. A total of 1137 operational taxonomic units (OTUs) were obtained among which 242 OTUs with >0.990 BLAST top hit similarity (21.3% of all detected OTUs) closely related to sequences belonging to -protists. A large portion (175 OTUs=72.3%) was identified at the species levels, including species typical for the Bulgarian Black Sea plankton community, as well as many that haven't been reported earlier in the Bulgarian Black Sea coast (124 OTUs=51.2%). Dinoflagellates were represented by the highest species number (77 OTUs comprising 31.8% of protist species), with dominant genera Gyrodinium and Heterocapsa. The present survey revealed the presence of 12 species listed as harmful, some of which have been previously overlooked, such as Cochlodinium polykrikoides, Karenia bicuneiformis, and Karlodinium veneficum. Species identification was possible for 10.3-36.0% of the detected OTUs in the six major supergroups. The frequency in Rhizaria was significantly lower than that in other major groups (p<0.05-0.01), implying difficulties in the classification from morphology-based observations. The metagenetic data had an insufficient resolution of the 18S rRNA gene for species identification in many genera. These issues may hamper the implementation of MPS-based surveys for plankton monitoring, especially for detecting harmful algal blooms (HAB). The sequencing technology is steadily improving and it is expected that sequence length and quality issues will be resolved in the near future. The ongoing efforts to register taxonomic information and quality controls in

  6. Effects of different eLISA-like configurations on massive black hole parameter estimation

    Science.gov (United States)

    Porter, Edward K.

    2015-09-01

    As the theme for the future L3 Cosmic Vision mission, ESA has recently chosen the "Gravitational Wave Universe." Within this program, a mission concept called eLISA has been proposed. This observatory has a current initial configuration consisting of four laser links between the three satellites, which are separated by a distance of one million kilometers, constructing a single-channel Michelson interferometer. However, the final configuration for the observatory will not be fixed until the end of this decade. With this in mind, we investigate the effect of different eLISA-like configurations on massive black hole detections. This work compares the results of a Bayesian inference study of 120 massive black hole binaries out to a redshift of z ˜13 for a 106 km arm length eLISA with four and six links, as well as a 2 ×106 km arm length observatory with four links. We demonstrate that the original eLISA configuration should allow us to recover the luminosity distance of the source with an error of less than 10% out to a redshift of z ˜4 , and a sky error box of Δ Ω ≤102 deg2 out to z ˜0.1 . In contrast, both alternative configurations suggest that we should be able to conduct the same parameter recovery with errors of less than 10% in luminosity distance out to z ˜12 and Δ Ω ≤102 deg2 out to z ˜0.4 . Using the information from these studies, we also infer that if we were able to construct a 2 Gm, six-link detector, the above values would shift to z ˜20 for luminosity distance and z ˜0.9 for sky error. While the final configuration will also be dependent on both technological and financial considerations, our study suggests that increasing the size of a two-arm detector is a viable alternative to the inclusion of a third arm in a smaller detector. More importantly, this work further suggests no clear scientific loss between either choice.

  7. The radial acceleration relation in disc galaxies in the MassiveBlack-II simulation

    Science.gov (United States)

    Tenneti, Ananth; Mao, Yao-Yuan; Croft, Rupert A. C.; Di Matteo, Tiziana; Kosowsky, Arthur; Zago, Fernando; Zentner, Andrew R.

    2018-03-01

    A strong correlation has been measured between the observed centripetal accelerations in galaxies and the accelerations implied by the baryonic components of galaxies. This empirical radial acceleration relation must be accounted for in any viable model of galaxy formation. We measure and compare the radial accelerations contributed by baryons and by dark matter in disc galaxies in the MassiveBlack-II hydrodynamic galaxy formation simulation. The sample of 1594 galaxies spans three orders of magnitude in luminosity and four in surface brightness, comparable to the observed sample from the Spitzer Photometry and Accurate Rotation Curves (SPARC) data set used by McGaugh, Lelli & Schombert. We find that radial accelerations contributed by baryonic matter only and by total matter are highly correlated, with only small scatter around their mean or median relation, despite the wide ranges of galaxy luminosity and surface brightness. We further find that the radial acceleration relation in this simulation differs from that of the SPARC sample, and can be described by a simple power law in the acceleration range we are probing.

  8. Probing the assembly history and dynamical evolution of massive black hole binaries with pulsar timing arrays

    Science.gov (United States)

    Chen, Siyuan; Middleton, Hannah; Sesana, Alberto; Del Pozzo, Walter; Vecchio, Alberto

    2017-06-01

    We consider the inverse problem in pulsar timing array (PTA) analysis, investigating what astrophysical information about the underlying massive black hole binary (MBHB) population can be recovered from the detection of a stochastic gravitational wave background (GWB). We employ a physically motivated model that connects the GWB spectrum to a series of parameters describing the underlying redshift evolution of the MBHB mass function and to the typical eccentricity they acquire while interacting with the dense environment of post-merger galactic nuclei. This allows the folding in of information about the spectral shape of the GWB into the analysis. The priors on the model parameters are assumed to be uninformative and consistent with the current lack of secure observations of sub-parsec MBHBs. We explore the implications of current upper limits and of future detections with a variety of PTA configurations. We confirm our previous finding that current upper limits can only place an upper bound on the overall MBHB merger rate. Depending on the properties of the array, future detections can also constrain several MBHB population models at different degrees of fidelity. In particular, a simultaneous detection of a steepening of the spectrum at high frequency and a bending at low frequency will place strong constraints on both the MBHB mass function and on the typical eccentricity of inspiralling MBHBs, providing insights into MBHB astrophysics unlikely to be achievable by any other means.

  9. Towards a formalism for mapping the spacetimes of massive compact objects: Bumpy black holes and their orbits

    International Nuclear Information System (INIS)

    Collins, Nathan A.; Hughes, Scott A.

    2004-01-01

    Astronomical observations have established that extremely compact, massive objects are common in the Universe. It is generally accepted that these objects are, in all likelihood, black holes. As observational technology has improved, it has become possible to test this hypothesis in ever greater detail. In particular, it is or will be possible to measure the properties of orbits deep in the strong field of a black hole candidate (using x-ray timing or future gravitational-wave measurements) and to test whether they have the characteristics of black hole orbits in general relativity. Past work has shown that, in principle, such measurements can be used to map the spacetime of a massive compact object, testing in particular whether the object's multipolar structure satisfies the rather strict constraints imposed by the black hole hypothesis. Performing such a test in practice requires that we be able to compare against objects with the 'wrong' multipole structure. In this paper, we present tools for constructing the spacetimes of bumpy black holes: objects that are almost black holes, but that have some multipoles with the wrong value. In this first analysis, we focus on objects with no angular momentum. Generalization to bumpy Kerr black holes should be straightforward, albeit labor intensive. Our construction has two particularly desirable properties. First, the spacetimes which we present are good deep into the strong field of the object--we do not use a 'large r' expansion (except to make contact with weak field intuition). Second, our spacetimes reduce to the exact black hole spacetimes of general relativity in a natural way, by dialing the 'bumpiness' of the black hole to zero. We propose that bumpy black holes can be used as the foundation for a null experiment: if black hole candidates are indeed the black holes of general relativity, their bumpiness should be zero. By comparing the properties of orbits in a bumpy spacetime with those measured from an

  10. Properties of galaxies around AGNs with the most massive supermassive black holes revealed by clustering analysis

    Science.gov (United States)

    Shirasaki, Yuji; Komiya, Yutaka; Ohishi, Masatoshi; Mizumoto, Yoshihiko

    2016-04-01

    We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0, which was performed to investigate the properties of galaxies associated with the AGNs and reveal the nature of the fueling mechanism of supermassive black holes (SMBHs). We used 8059 AGNs/quasi-stellar objects (QSOs) for which virial masses of individual SMBHs were measured, and divided them into four mass groups.Cross-correlation analysis was performed to reconfirm our previous result that cross-correlation length increases with SMBH mass MBH; we obtained consistent results. A linear bias of AGN for each mass group was measured as 1.47 for MBH = 107.5-108.2 M⊙ and 3.08 for MBH = 109-1010 M⊙. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color Dopt-IR was estimated from a spectral energy distribution (SED) constructed from a catalog derived by merging the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) catalogs. The distributions of color and luminosity were derived by a subtraction method, which does not require redshift information of galaxies. The main results of this work are as follows. (1) A linear bias increases by a factor of two from the lower-mass group to the highest-mass group. (2) The environment around AGNs with the most massive SMBHs (MBH > 109 M⊙) is dominated by red sequence galaxies. (3) Marginal indication of decline in luminosity function at dimmer side of MIR > -19.5 is found for galaxies around AGNs with MBH = 108.2-109 M⊙ and nearest redshift group (z = 0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where a large fraction of galaxies have been transited to the red sequence. The accretion of hot halo gas as well as recycled gas from evolving stars can be one of the plausible mechanisms to fuel the SMBHs above ˜ 109 M⊙.

  11. Massive black holes and light-element nucleosynthesis in a baryonic universe

    Science.gov (United States)

    Gnedin, Nickolay Y.; Ostriker, Jeremiah P.; Rees, Martin J.

    1995-01-01

    We reexamine the model proposed by Gnedin & Ostriker (1992) in which Jeans mass black holes (M(sub BH) approximately = 10(exp 6) solar mass) form shortly after decoupling. There is no nonbaryonic dark matter in this model, but we examine the possibility that Omega(sub b) is considerably larger than given by normal nucleosynthesis. Here we allow for the fact that much of the high baryon-to-photon ratio material will collapse leaving the universe of remaining material with light-element abundances more in accord with the residual baryonic density (approximately = 10(exp -2)) than with Omega(sub 0) and the initial baryonic density (approximately = 10(exp -1)). We find that no reasonable model can be made with random-phase density fluctuations, if the power on scales smaller than 10(exp 6) solar mass is as large as expected. However, phase-correlated models of the type that might occur in connection with topological singularities can be made with Omega(sub b) h(exp 2) = 0.013 +/- 0.001, 0.15 approximately less than Omega(sub 0) approximately less than 0.4, which are either flat (Omega(sub lambda) = 1 - Omega(sub 0)) or open (Omega(sub lambda) = 0) and which satisfy all the observational constraints which we apply, including the large baryon-to-total mass ratio found in the X-ray clusters. The remnant baryon density is thus close to that obtained in the standard picture (Omega(sub b) h(exp 2) = 0.0125 +/- 0.0025; Walker et al. 1991). The spectral index implied for fluctuations in the baryonic isocurvature scenario, -1 less than m less than 0, is in the range expected by other arguments based on large-scale structure and microwave fluctuation constraints. The dark matter in this picture is in the form of massive black holes. Accretion onto them at early epochs releases high-energy photons which significantly heat and reionize the universe. But photodissociation does not materially change light-element abundances. A typical model gives bar-y approximately = 1 x 10(exp -5

  12. 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.

  13. Tidal Disruption of Inclined or Eccentric Binaries by Massive Black Holes

    Science.gov (United States)

    Brown, Harriet; Kobayashi, Shiho; Rossi, Elena M.; Sari, Re'em

    2018-04-01

    Binary stars that are on close orbits around massive black holes (MBH) such as Sgr A* in the centre of the Milky Way are liable to undergo tidal disruption and eject a hypervelocity star. We study the interaction between such a MBH and circular binaries for general binary orientations and penetration depths (i.e. binaries penetrate into the tidal radius around the BH). We show that for very deep penetrators, almost all binaries are disrupted when the binary rotation axis is roughly oriented toward the BH or it is in the opposite direction. The surviving chance becomes significant when the angle between the binary rotation axis and the BH direction is between 0.15π and 0.85π. The surviving chance is as high as ˜20% when the binary rotation axis is perpendicular to the BH direction. However, for shallow penetrators, the highest disruption chance is found in such a perpendicular case, especially in the prograde case. This is because the dynamics of shallow penetrators is more sensitive to the relative orientation of the binary and orbital angular momenta. We provide numerical fits to the disruption probability and energy gain at the the BH encounter as a function of the penetration depth. The latter can be simply rescaled in terms of binary masses, their initial separation and the binary-to-BH mass ratio to evaluate the ejection velocity of a binary members in various systems. We also investigate the disruption of coplanar, eccentric binaries by a MBH. It is shown that for highly eccentric binaries retrograde orbits have a significantly increased disruption probability and ejection velocities compared to the circular binaries.

  14. The influence of Massive Black Hole Binaries on the Morphology of Merger Remnants

    Science.gov (United States)

    Bortolas, E.; Gualandris, A.; Dotti, M.; Read, J. I.

    2018-03-01

    Massive black hole (MBH) binaries, formed as a result of galaxy mergers, are expected to harden by dynamical friction and three-body stellar scatterings, until emission of gravitational waves (GWs) leads to their final coalescence. According to recent simulations, MBH binaries can efficiently harden via stellar encounters only when the host geometry is triaxial, even if only modestly, as angular momentum diffusion allows an efficient repopulation of the binary loss cone. In this paper, we carry out a suite of N-body simulations of equal-mass galaxy collisions, varying the initial orbits and density profiles for the merging galaxies and running simulations both with and without central MBHs. We find that the presence of an MBH binary in the remnant makes the system nearly oblate, aligned with the galaxy merger plane, within a radius enclosing 100 MBH masses. We never find binary hosts to be prolate on any scale. The decaying MBHs slightly enhance the tangential anisotropy in the centre of the remnant due to angular momentum injection and the slingshot ejection of stars on nearly radial orbits. This latter effect results in about 1% of the remnant stars being expelled from the galactic nucleus. Finally, we do not find any strong connection between the remnant morphology and the binary hardening rate, which depends only on the inner density slope of the remnant galaxy. Our results suggest that MBH binaries are able to coalesce within a few Gyr, even if the binary is found to partially erase the merger-induced triaxiality from the remnant.

  15. STEADY-STATE RELATIVISTIC STELLAR DYNAMICS AROUND A MASSIVE BLACK HOLE

    International Nuclear Information System (INIS)

    Bar-Or, Ben; Alexander, Tal

    2016-01-01

    A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the “loss cone,” which take them into the MBH, or close enough to interact strongly with it. The resulting phenomena, e.g., tidal heating and disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, can produce observable signatures and thereby reveal the MBH, affect its mass and spin evolution, test strong gravity, and probe stars and gas near the MBH. These continuous stellar loss and resupply processes shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss cone of a non-spinning MBH in steady state, analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclosed stellar mass, in-plane precession due to general relativity, dissipation by GW, uncorrelated two-body relaxation, correlated resonant relaxation (RR), and adiabatic invariance due to secular precession, using a rigorously derived description of correlated post-Newtonian dynamics in the diffusion limit. We argue that general maximal entropy considerations strongly constrain the orbital diffusion in steady state, irrespective of the relaxation mechanism. We identify the exact phase-space separatrix between plunges and inspirals, and predict their steady-state rates. We derive the dependence of the rates on the mass of the MBH, show that the contribution of RR in steady state is small, and discuss special cases where unquenched RR in restricted volumes of phase-space may affect the steady state substantially

  16. Slowly decaying resonances of charged massive scalar fields in the Reissner–Nordström black-hole spacetime

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2016-10-01

    Full Text Available We determine the characteristic timescales associated with the linearized relaxation dynamics of the composed Reissner–Nordström-black-hole-charged-massive-scalar-field system. To that end, the quasinormal resonant frequencies {ωn(μ,q,M,Q}n=0n=∞ which characterize the dynamics of a charged scalar field of mass μ and charge coupling constant q in the charged Reissner–Nordström black-hole spacetime of mass M and electric charge Q are determined analytically in the eikonal regime 1≪Mμblack-hole electric charge Q/M, the imaginary part of the resonant oscillation frequency is a monotonically decreasing function of the dimensionless ratio μ/q. In particular, it is shown that the quasinormal resonance spectrum is characterized by the asymptotic behavior ℑω→0 in the limiting case Mμ→qQ. This intriguing finding implies that the composed Reissner–Nordström-black-hole-charged-massive-scalar-field system is characterized by extremely long relaxation times τrelax≡1/ℑω→∞ in the Mμ/qQ→1− limit.

  17. Effect of adding Black seeds, Nigella Sativa, in growing lambs diets on their performance

    International Nuclear Information System (INIS)

    Saleh, S.A.

    2006-01-01

    Eighteen growing male lambs, four months old, were randomly divided into two equal groups, nine in each. Animals of each group were fed on one of the two tested diets. The first group fed on the basal diet as a control, while the other one fed the basal diet supplemented daily with 5 grams/head of black seeds. Wheat straw and concentrate feed mixture (CFM) were used at the ratio of 30:70, respectively. Lambs were weighed at the beginning of the experimental period then at three weeks intervals till the end of the experiment, which lasted for 118 days. At the end of experimental period, four animals from each group were used to evaluate the digestibility and nutritive values of the two experimental diets. Rumen liquor samples were taken from three animals of each group. Blood samples were withdrawn from the jugular vein of each animal in the morning before feeding once each three weeks. The results showed that lambs fed diet supplemented with Black seed had significant higher digestibility values for CP, EE and NFE than those fed control diet. The percentage of apparent nitrogen utilization showed similar trend. In addition, the total VFAs was also affected by supplementation while the values of ph and ammonia-N were not affected by treatment diet. Average daily weight gain (ADG) and feed efficiency (Kg DMI/Kg gain) were better for treated group than control group. Significant differences were found also in total protein, albumin, globulin, urea, total cholesterol, triglycerides and T3 values. These Results indicated that Black seeds could be successfully used in formulating the concentrate feed mixture of growing lambs up to 5 grams/head without any negative effects on their performance and health

  18. Transition from adiabatic inspiral to geodesic plunge for a compact object around a massive Kerr black hole: Generic orbits

    International Nuclear Information System (INIS)

    Sundararajan, Pranesh A.

    2008-01-01

    The inspiral of a stellar mass compact object falling into a massive Kerr black hole can be broken into three different regimes: An adiabatic inspiral phase, where the inspiral time scale is much larger than the orbital period; a late-time radial infall, which can be approximated as a plunging geodesic; and a regime where the body transitions from the inspiral to plunge. In earlier work, Ori and Thorne have outlined a method to compute the trajectory during this transition for a compact object in a circular, equatorial orbit. We generalize this technique to include inclination and eccentricity

  19. The unusual lensing BCG in Abell 1201: A steep IMF gradient, or an ultra-massive central black hole?

    Science.gov (United States)

    Smith, Russell

    2016-10-01

    Abell 1201 is a cluster of galaxies at z=0.17, with a brightest cluster galaxy (BCG) which acts as a gravitational lens to a background surce at z=0.45. The lensing configuration is unusual, with a single bright arc formed at small radius ( 5kpc), where the stars are expected to contribute substantially to the total lensing mass. Using VLT/MUSE data, we have recently discovered a faint counter-image to the main arc, located just 0.6 from the lens centre. This image is not predicted at all in lensing models which incorporate the mass contributions from stars (following the observed light profile) and dark matter. Modelling shows that the formation of the counter-image requires additional mass at small radius. Possible solutions include (a) imposing a gradient of the stellar-mass-to-light ratio, reflecting a heavier initial mass function (IMF) in the galaxy centre, or (b) adding a central black hole with mass above ten billion solar masses, comparable to the largest dynamical measurements. The first scenario would be relevant to ongoing controversies concering possible non-standard IMFs in massive elliptical galaxies. The second explanation would be the first lensing-based detection of a central black hole, with implications for the still sparsely-populated upper end of the black hole scaling relations.The two alternative models yield different predictions for the morphology of the counter-image. Our proposed WFC3/UVIS observations will establish whether the image is (a) a radial arc, supporting the IMF gradient interpretation, or (b) a compact counter-image, confirming the ultra-massive black hole scenario. HST resolution is essential for this measurement.

  20. Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system.

    Science.gov (United States)

    Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M; Fragos, Tassos; Willems, Bart; Orosz, Jerome A; Liu, Jifeng; Kalogera, Vassiliki

    2010-11-04

    The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ∼16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.

  1. Topological charged black holes in massive gravity's rainbow and their thermodynamical analysis through various approaches

    Energy Technology Data Exchange (ETDEWEB)

    Hendi, S.H., E-mail: hendi@shirazu.ac.ir [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Eslam Panah, B. [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Panahiyan, S. [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, Tehran 19839 (Iran, Islamic Republic of)

    2017-06-10

    Violation of Lorentz invariancy in the high energy quantum gravity motivates one to consider an energy dependent spacetime with massive deformation of standard general relativity. In this paper, we take into account an energy dependent metric in the context of a massive gravity model to obtain exact solutions. We investigate the geometry of black hole solutions and also calculate the conserved and thermodynamic quantities, which are fully reproduced by the analysis performed with the standard techniques. After examining the validity of the first law of thermodynamics, we conduct a study regarding the effects of different parameters on thermal stability of the solutions. In addition, we employ the relation between cosmological constant and thermodynamical pressure to study the possibility of phase transition. Interestingly, we will show that for the specific configuration considered in this paper, van der Waals like behavior is observed for different topology. In other words, for flat and hyperbolic horizons, similar to spherical horizon, a second order phase transition and van der Waals like behavior are observed. Furthermore, we use geometrical method to construct phase space and study phase transition and bound points for these black holes. Finally, we obtain critical values in extended phase space through the use of a new method.

  2. Constraining The Abundance Of Massive Black Hole Binaries By Spectroscopic Monitoring Of Quasars With Offset Broad Emission Lines

    Science.gov (United States)

    Liu, Xin; Shen, Y.

    2012-05-01

    A fraction of quasars have long been known to show significant bulk velocity offsets (of a few hundred to thousands of km/s) in the broad permitted emission lines with respect to host galaxy systemic redshift. Various scenarios may explain these features such as massive black hole binaries or broad line region gas kinematics. As previously demonstrated by the dedicated work of Eracleous and colleagues, long-term spectroscopic monitoring provides a promising test to discriminate between alternative scenarios. Here, we present a sample of 300 shifted-line quasars homogeneously selected from the SDSS DR7. For 60 of them, we have conducted second-epoch optical spectra using MMT/BCS, ARC 3.5m/DIS, and/or FLWO 1.5m/FAST. These new observations, combined with the existing SDSS spectra, enable us to constrain the velocity drifts of these shifted broad lines with time baselines of a few years up to a decade. Previous work has been focusing on objects with extreme velocity offsets: > 1000 km/s. Our work extends to the parameter space of smaller velocity offsets, where larger velocity drifts would be expected in the binary scenario. Our results may be used to identify strong candidates for and to constrain the abundance of massive black hole binaries, which are expected in the hierarchical universe, but have so far been illusive.

  3. THE MOST MASSIVE ACTIVE BLACK HOLES AT z ∼ 1.5-3.5 HAVE HIGH SPINS AND RADIATIVE EFFICIENCIES

    International Nuclear Information System (INIS)

    Trakhtenbrot, Benny

    2014-01-01

    The radiative efficiencies (η) of 72 luminous unobscured active galactic nuclei at z ∼ 1.5-3.5, powered by some of the most massive black holes (BHs), are constrained. The analysis is based on accretion disk (AD) models, which link the continuum luminosity at rest-frame optical wavelengths and the BH mass (M BH ) to the accretion rate through the AD, M-dot AD . The data are gathered from several literature samples with detailed measurements of the Hβ emission line complex, observed at near-infrared bands. When coupled with standard estimates of bolometric luminosities (L bol ), the analysis suggests high radiative efficiencies, with most of the sources showing η > 0.2, that is, higher than the commonly assumed value of 0.1, and the expected value for non-spinning BHs (η = 0.057). Even under more conservative assumptions regarding L bol (i.e., L bol = 3 × L 5100 ), most of the extremely massive BHs in the sample (i.e., M BH ≳ 3 × 10 9 M ☉ ) show radiative efficiencies which correspond to very high BH spins (a * ), with typical values well above a * ≅ 0.7. These results stand in contrast to the predictions of a ''spin-down'' scenario, in which a series of randomly oriented accretion episodes leads to a * ∼ 0. Instead, the analysis presented here strongly supports a ''spin-up'' scenario, which is driven by either prolonged accretion or a series of anisotropically oriented accretion episodes. Considering the fact that these extreme BHs require long-duration or continuous accretion to account for their high masses, it is argued that the most probable scenario for the super-massive black holes under study is that of an almost continuous sequence of randomly yet not isotropically oriented accretion episodes

  4. BINARY DISRUPTION BY MASSIVE BLACK HOLES: HYPERVELOCITY STARS, S STARS, AND TIDAL DISRUPTION EVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Bromley, Benjamin C. [Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J.; Geller, Margaret J.; Brown, Warren R., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: wbrown@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2012-04-20

    We examine whether disrupted binary stars can fuel black hole growth. In this mechanism, tidal disruption produces a single hypervelocity star (HVS) ejected at high velocity and a former companion star bound to the black hole. After a cluster of bound stars forms, orbital diffusion allows the black hole to accrete stars by tidal disruption at a rate comparable to the capture rate. In the Milky Way, HVSs and the S star cluster imply similar rates of 10{sup -5} to 10{sup -3} yr{sup -1} for binary disruption. These rates are consistent with estimates for the tidal disruption rate in nearby galaxies and imply significant black hole growth from disrupted binaries on 10 Gyr timescales.

  5. Relativistic boost as the cause of periodicity in a massive black-hole binary candidate.

    Science.gov (United States)

    D'Orazio, Daniel J; Haiman, Zoltán; Schiminovich, David

    2015-09-17

    Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries, most recently in PG 1302-102, which has a short rest-frame optical period of four years (ref. 6). If the orbital period of the black-hole binary matches this value, then for the range of estimated black-hole masses, the components would be separated by 0.007-0.017 parsecs, implying relativistic orbital speeds. There has been much debate over whether black-hole orbits could be smaller than one parsec (ref. 7). Here we report that the amplitude and the sinusoid-like shape of the variability of the light curve of PG 1302-102 can be fitted by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a two to three times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival ultraviolet data. Follow-up ultraviolet and optical observations in the next few years can further test this prediction and confirm the existence of a binary black hole in the relativistic regime.

  6. The close environments of accreting massive black holes are shaped by radiative feedback.

    Science.gov (United States)

    Ricci, Claudio; Trakhtenbrot, Benny; Koss, Michael J; Ueda, Yoshihiro; Schawinski, Kevin; Oh, Kyuseok; Lamperti, Isabella; Mushotzky, Richard; Treister, Ezequiel; Ho, Luis C; Weigel, Anna; Bauer, Franz E; Paltani, Stephane; Fabian, Andrew C; Xie, Yanxia; Gehrels, Neil

    2017-09-27

    The majority of the accreting supermassive black holes in the Universe are obscured by large columns of gas and dust. The location and evolution of this obscuring material have been the subject of intense research in the past decades, and are still debated. A decrease in the covering factor of the circumnuclear material with increasing accretion rates has been found by studies across the electromagnetic spectrum. The origin of this trend may be driven by the increase in the inner radius of the obscuring material with incident luminosity, which arises from the sublimation of dust; by the gravitational potential of the black hole; by radiative feedback; or by the interplay between outflows and inflows. However, the lack of a large, unbiased and complete sample of accreting black holes, with reliable information on gas column density, luminosity and mass, has left the main physical mechanism that regulates obscuration unclear. Here we report a systematic multi-wavelength survey of hard-X-ray-selected black holes that reveals that radiative feedback on dusty gas is the main physical mechanism that regulates the distribution of the circumnuclear material. Our results imply that the bulk of the obscuring dust and gas is located within a few to tens of parsecs of the accreting supermassive black hole (within the sphere of influence of the black hole), and that it can be swept away even at low radiative output rates. The main physical driver of the differences between obscured and unobscured accreting black holes is therefore their mass-normalized accretion rate.

  7. Merging between a Central Massive Black Hole and a Compact Stellar System: A Clue to the Origin of M31'S Nucleus

    OpenAIRE

    Bekki, Kenji

    2000-01-01

    The central bulge of M31 is observed to have two distinct brightness peaks with the separation of $\\sim$ 2 pc. Tremaine (1995) recently proposed a new idea that the M31's nucleus is actually a single thick eccentric disk surrounding the central super-massive black hole. In order to explore the origin of the proposed eccentric disk, we numerically investigate the dynamical evolution of a merger between a central massive black hole with the mass of $\\sim$ $10^7$ $M_{\\odot}$ and a compact stella...

  8. Effects of turbulence and rotation on protostar formation as a precursor of massive black holes

    NARCIS (Netherlands)

    Van Borm, C.; Bovino, S.; Latif, M. A.; Schleicher, D. R. G.; Spaans, M.; Grassi, T.

    2014-01-01

    Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in ≳104 K haloes, forming a supermassive or quasi-star as an intermediate stage. Aims: We explore the formation of a protostar resulting from the collapse of primordial gas in

  9. Supermassive black hole feeding and star formation in massive accretion discs

    Czech Academy of Sciences Publication Activity Database

    Šubr, Ladislav

    2008-01-01

    Roč. 79, č. 4 (2008), s. 1071-1074 ISSN 0037-8720. [Central Kiloparsec - Active Galactic Nuclei and Their Hosts. Ierapetra, Crete, 04.06.2008-06.06.2008] R&D Projects: GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : black holes Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  10. Formation of massive black holes through runaway collisions in dense young star clusters

    NARCIS (Netherlands)

    Portegies Zwart, S.F.; Baumgardt, H.; Hut, P.; Makino, J.; McMillan, S.L.W.

    2004-01-01

    A luminous X-ray source is associated with MGG 11-a cluster of young stars ~200pc from the centre of the starburst galaxy M 82 (refs 1, 2). The properties of this source are best explained by invoking a black hole with a mass of at least 350 solar masses (350Msolar), which is intermediate between

  11. Massive-spin-1/2 wave around a Kerr-Newman black hole

    International Nuclear Information System (INIS)

    Lee, C.H.

    1977-01-01

    Using the separation of variables of the Dirac equations for the electron in the Kerr-Newman geometry, it is explicitly shown that the super-radiant scattering is not allowed for the electron wave on a Kerr-Newman black hole

  12. Relativistic jet activity from the tidal disruption of a star by a massive black hole.

    Science.gov (United States)

    Burrows, D N; Kennea, J A; Ghisellini, G; Mangano, V; Zhang, B; Page, K L; Eracleous, M; Romano, P; Sakamoto, T; Falcone, A D; Osborne, J P; Campana, S; Beardmore, A P; Breeveld, A A; Chester, M M; Corbet, R; Covino, S; Cummings, J R; D'Avanzo, P; D'Elia, V; Esposito, P; Evans, P A; Fugazza, D; Gelbord, J M; Hiroi, K; Holland, S T; Huang, K Y; Im, M; Israel, G; Jeon, Y; Jeon, Y-B; Jun, H D; Kawai, N; Kim, J H; Krimm, H A; Marshall, F E; P Mészáros; Negoro, H; Omodei, N; Park, W-K; Perkins, J S; Sugizaki, M; Sung, H-I; Tagliaferri, G; Troja, E; Ueda, Y; Urata, Y; Usui, R; Antonelli, L A; Barthelmy, S D; Cusumano, G; Giommi, P; Melandri, A; Perri, M; Racusin, J L; Sbarufatti, B; Siegel, M H; Gehrels, N

    2011-08-24

    Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

  13. Effects of turbulence and rotation on protostar formation as a precursor of massive black holes

    DEFF Research Database (Denmark)

    Van Borm, C.; Bovino, S.; Latif, M. A.

    2014-01-01

    Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in ≳104 K haloes, forming a supermassive or quasi-star as an intermediate stage. Aims. We explore the formation of a protostar resulting from the collapse of primordial gas...

  14. Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation

    Science.gov (United States)

    Banerjee, Sambaran

    2017-05-01

    Stellar-remnant black holes (BH) in dense stellar clusters have always drawn attention due to their potential in a number of phenomena, especially the dynamical formation of binary black holes (BBH), which potentially coalesce via gravitational-wave radiation. This study presents a preliminary set of evolutionary models of compact stellar clusters with initial masses ranging over 1.0 × 104-5.0 × 104 M⊙, and half-mass radius of 2 or 1 pc, which is typical for young massive and starburst clusters. They have metallicities between 0.05 Z⊙ and Z⊙. Including contemporary schemes for stellar wind and remnant formation, such model clusters are evolved, for the first time, using the state-of-the-art direct N-body evolution program nbody7, until their dissolution or at least for 10 Gyr. That way, a self-regulatory behaviour in the effects of dynamical interactions among the BHs is demonstrated. In contrast to earlier studies, the BBH coalescences obtained in these models show a prominence in triple-mediated coalescences while being bound to the clusters, compared to those occurring among the BBHs that are dynamically ejected from the clusters. A broader mass spectrum of the BHs and lower escape velocities of the clusters explored here might cause this difference, which is yet to be fully understood. Among the BBH coalescences obtained here, there are ones that resemble the detected GW151226, LVT151012 and GW150914 events and also ones that are even more massive. A preliminary estimate suggests few 10-100 s of BBH coalescences per year, originating due to dynamics in stellar clusters that can be detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) at its design sensitivity.

  15. Microlensing of sub-parsec massive binary black holes in lensed QSOs: Light curves and size-wavelength relation

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Chang-Shuo; Lu, Youjun; Mao, Shude [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Yu, Qingjuan [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Wambsganss, Joachim, E-mail: yancs@nao.cas.cn, E-mail: luyj@nao.cas.cn [Astronomisches Rechen-Institut am Zentrum für Astronomie der Universität Heidelberg, Mönchhofstrasse 12-14, D-69120 Heidelberg (Germany)

    2014-04-01

    Sub-parsec binary massive black holes (BBHs) have long been thought to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circumbinary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circumbinary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii of the emission region at different wavelengths from mock light curves and find that the obtained half-light radius versus wavelength relations of BBH QSO systems can be much flatter than those of single MBH QSO systems at a wavelength range determined by the BBH parameters, such as the total mass, mass ratio, separation, accretion rates, etc. The difference is primarily due to the existence of the gap. Such unique features on the light curves and half-light radius-wavelength relations of BBH QSO systems can be used to select and probe sub-parsec BBHs in a large number of lensed QSOs to be discovered by current and future surveys, including the Panoramic Survey Telescope and Rapid Response System, the Large Synoptic Survey telescope, and Euclid.

  16. Electron-positron pair production in a hot accretion plasma around a massive black hole

    International Nuclear Information System (INIS)

    Takahara, Fumio; Kusunose, Masaaki.

    1985-01-01

    We investigate the electron-positron pair production in a hot accretion plasma around a supermassive black hole in connection with active galactic nuclei. Assuming that an optically thin two-temperature plasma is produced in the vicinity of the central black hole, we examine the condition for the significant pair production by comparing relevant time scales. Since the pair production is dominated by collisions between hard photons, the conditions for significant pair production depend on the production rate of hard photons. We examine the case where the unsaturated Comptonization of soft photons produces hard photons as well as that of bremsstrahlung. We show that significant pair production occurs for a moderately high accretion rate with relatively slow accretion flow as compared to the free fall velocity in both cases. Possible consequences of pair production are briefly discussed. (author)

  17. A massive binary black-hole system in OJ 287 and a test of general relativity.

    Science.gov (United States)

    Valtonen, M J; Lehto, H J; Nilsson, K; Heidt, J; Takalo, L O; Sillanpää, A; Villforth, C; Kidger, M; Poyner, G; Pursimo, T; Zola, S; Wu, J-H; Zhou, X; Sadakane, K; Drozdz, M; Koziel, D; Marchev, D; Ogloza, W; Porowski, C; Siwak, M; Stachowski, G; Winiarski, M; Hentunen, V-P; Nissinen, M; Liakos, A; Dogru, S

    2008-04-17

    Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later.

  18. The connection between the formation of galaxies and that of their central supermassive black holes.

    Science.gov (United States)

    Haehnelt, Martin G

    2005-03-15

    Massive black holes appear to be an essential ingredient of massive galactic bulges but little is known yet to what extent massive black holes reside in dwarf galaxies and globular clusters. Massive black holes most likely grow by a mixture of merging and accretion of gas in their hierarchically merging host galaxies. While the hierarchical merging of dark matter structures extends to sub-galactic scales and very high redshift, it is uncertain if the same is true for the build-up of massive black holes. I discuss here some of the relevant problems and open questions.

  19. Stability of the Schwarzschild–de Sitter black hole in the dRGT massive gravity theory

    International Nuclear Information System (INIS)

    Kodama, Hideo; Arraut, Ivan

    2014-01-01

    The Schwarzschild–de Sitter solution in the Einstein theory with a positive cosmological constant Λ=m 2 /α becomes an exact solution to the de Rham–Gabadadze–Tolley (dRGT) nonlinear massive gravity theory with the mass parameter m when the theory parameters α and β satisfy the relation β=α 2 . We study the perturbative behavior of this black hole solution in the nonlinear dRGT theory with β=α 2 . We find that the linear perturbation equations become identical to those for the vacuum Einstein theory when they are expressed in terms of gauge-invariant variables. This implies that this black hole is stable in the dRGT theory as far as the spacetime structure is concerned, in contrast to the case of the bi-Schwarzschild solution in the bi-metric theory. However, we have also found a pathological feature that the general solution to the perturbation equations contain a single arbitrary function of spacetime coordinates. This implies a degeneracy of dynamics in the Stückelberg field sector at the linear perturbation level in this background. The physical significance of this degeneracy depends on how the Stückelberg fields couple observable fields

  20. Flows of X-ray gas reveal the disruption of a star by a massive black hole.

    Science.gov (United States)

    Miller, Jon M; Kaastra, Jelle S; Miller, M Coleman; Reynolds, Mark T; Brown, Gregory; Cenko, S Bradley; Drake, Jeremy J; Gezari, Suvi; Guillochon, James; Gultekin, Kayhan; Irwin, Jimmy; Levan, Andrew; Maitra, Dipankar; Maksym, W Peter; Mushotzky, Richard; O'Brien, Paul; Paerels, Frits; de Plaa, Jelle; Ramirez-Ruiz, Enrico; Strohmayer, Tod; Tanvir, Nial

    2015-10-22

    Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/ultraviolet flares in galactic centres. Prior studies based on modelling decaying flux trends have been able to estimate broad properties, such as the mass accretion rate. Here we report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 043234. Variability within the absorption-dominated spectra indicates that the gas is relatively close to the black hole. Narrow linewidths indicate that the gas does not stretch over a large range of radii, giving a low volume filling factor. Modest outflow speeds of a few hundred kilometres per second are observed; these are below the escape speed from the radius set by variability. The gas flow is consistent with a rotating wind from the inner, super-Eddington region of a nascent accretion disk, or with a filament of disrupted stellar gas near to the apocentre of an elliptical orbit. Flows of this sort are predicted by fundamental analytical theory and more recent numerical simulations.

  1. The Most Massive Galaxies and Black Holes Allowed by ΛCDM

    Science.gov (United States)

    Behroozi, Peter; Silk, Joseph

    2018-04-01

    Given a galaxy's stellar mass, its host halo mass has a lower limit from the cosmic baryon fraction and known baryonic physics. At z > 4, galaxy stellar mass functions place lower limits on halo number densities that approach expected ΛCDM halo mass functions. High-redshift galaxy stellar mass functions can thus place interesting limits on number densities of massive haloes, which are otherwise very difficult to measure. Although halo mass functions at z relation, confirming the expectation from Lauer bias. Finally, we present a public code to evaluate the probability of an apparently ΛCDM-inconsistent high-mass halo being detected given the combined effects of multiple surveys and observational errors.

  2. Universality in the relaxation dynamics of the composed black-hole-charged-massive-scalar-field system: The role of quantum Schwinger discharge

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2015-07-01

    Full Text Available The quasinormal resonance spectrum {ωn(μ,q,M,Q}n=0n=∞ of charged massive scalar fields in the charged Reissner–Nordström black-hole spacetime is studied analytically in the large-coupling regime qQ≫Mμ (here {μ,q} are respectively the mass and charge coupling constant of the field, and {M,Q} are respectively the mass and electric charge of the black hole. This physical system provides a striking illustration for the validity of the universal relaxation bound τ×T≥ħ/π in black-hole physics (here τ≡1/ℑω0 is the characteristic relaxation time of the composed black-hole-scalar-field system, and T is the Bekenstein–Hawking temperature of the black hole. In particular, it is shown that the relaxation dynamics of charged massive scalar fields in the charged Reissner–Nordström black-hole spacetime may saturate this quantum time-times-temperature inequality. Interestingly, we prove that potential violations of the bound by light scalar fields are excluded by the Schwinger-type pair-production mechanism (a vacuum polarization effect, a quantum phenomenon which restricts the physical parameters of the composed black-hole-charged-field system to the regime qQ≪M2μ2/ħ.

  3. THE MISSING GOLIATH'S SLINGSHOT: MASSIVE BLACK HOLE RECOIL AT M83

    International Nuclear Information System (INIS)

    Dottori, Horacio; Diaz, Ruben J.; Facundo Albacete-Colombo, Juan; Mast, Damian

    2010-01-01

    The Fanaroff-Riley II radio source J133658.3-295105, which is also an X-ray source, appears to be projected onto the disk of the barred-spiral galaxy M83 at about 60'' from the galaxy's optical nucleus. J133658.3-295105 and its radio lobes are aligned with the optical nucleus of M 83 and two other radio sources, neither of which are supernova remnants or H II regions. Due to this peculiar on-the-sky projection, J133658.3-295105 was previously studied by Gemini+GMOS optical spectroscopy, which marginally revealed the presence of Hα in emission receding at 130 km s -1 with respect to the optical nucleus. In this Letter, we reanalyze the Chandra spectroscopy carried out in 2000. We show that J133658.3-295105 presents an Fe Kα emission line at a redshift of z = 0.018. This redshift is compatible with a black hole at the distance of M 83. We discuss similarities to the recently reported micro-quasar in NGC 5408. This finding reinforces the kicked-off black hole scenario for J133658.3-295105.

  4. Feedback by Massive Black Holes in Gas-rich Dwarf Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Silk, Joseph [Institut d’Astrophysique, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Blvd Arago, F-75014 Paris (France); AIM-Paris-Saclay, CEA/DSM/IRFU, CNRS, Univ Paris 7, F-91191, Gif-sur-Yvette (France); Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2017-04-10

    Could there be intermediate-mass black holes in essentially all old dwarf galaxies? I argue that current observations of active galactic nuclei in dwarfs allow such a radical hypothesis that provides early feedback during the epoch of galaxy formation and potentially provides a unifying explanation for many, if not all, of the dwarf galaxy anomalies, such as the abundance, core-cusp, “too-big-to-fail,” ultra-faint, and baryon-fraction issues. I describe the supporting arguments, which are largely circumstantial, and discuss a number of tests. There is no strong motivation for modifying the nature of cold dark matter in order to explain any of the dwarf galaxy “problems.”.

  5. Super-massive binary black holes and emission lines in active galactic nuclei

    Science.gov (United States)

    Popović, Luka Č.

    2012-02-01

    It is now agreed that mergers play an essential role in the evolution of galaxies and therefore that mergers of supermassive black holes (SMBHs) must have been common. We see the consequences of past supermassive binary black holes (SMBs) in the light profiles of so-called 'core ellipticals' and a small number of SMBs have been detected. However, the evolution of SMBs is poorly understood. Theory predicts that SMBs should spend a substantial amount of time orbiting at velocities of a few thousand kilometers per second. If the SMBs are surrounded by gas observational effects might be expected from accretion onto one or both of the SMBHs. This could result in a binary Active Galactic Nucleus (AGN) system. Like a single AGN, such a system would emit a broad band electromagnetic spectrum and broad and narrow emission lines. The broad emission spectral lines emitted from AGNs are our main probe of the geometry and physics of the broad line region (BLR) close to the SMBH. There is a group of AGNs that emit very broad and complex line profiles, showing two displaced peaks, one blueshifted and one redshifted from the systemic velocity defined by the narrow lines, or a single such peak. It has been proposed that such line shapes could indicate an SMB system. We discuss here how the presence of an SMB will affect the BLRs of AGNs and what the observational consequences might be. We review previous claims of SMBs based on broad line profiles and find that they may have non-SMB explanations as a consequence of a complex BLR structure. Because of these effects it is very hard to put limits on the number of SMBs from broad line profiles. It is still possible, however, that unusual broad line profiles in combination with other observational effects (line ratios, quasi-periodical oscillations, spectropolarimetry, etc.) could be used for SMBs detection. Some narrow lines (e.g., [O III]) in some AGNs show a double-peaked profile. Such profiles can be caused by streams in the Narrow

  6. Post-Newtonian evolution of massive black hole triplets in galactic nuclei - II. Survey of the parameter space

    Science.gov (United States)

    Bonetti, Matteo; Haardt, Francesco; Sesana, Alberto; Barausse, Enrico

    2018-04-01

    Massive black hole binaries (MBHBs) are expected to form at the centre of merging galaxies during the hierarchical assembly of the cosmic structure, and are expected to be the loudest sources of gravitational waves (GWs) in the low frequency domain. However, because of the dearth of energy exchanges with background stars and gas, many of these MBHBs may stall at separations too large for GW emission to drive them to coalescence in less than a Hubble time. Triple MBH systems are then bound to form after a further galaxy merger, triggering a complex and rich dynamics that can eventually lead to MBH coalescence. Here we report on the results of a large set of numerical simulations, where MBH triplets are set in spherical stellar potentials and MBH dynamics is followed through 2.5 post-Newtonian order in the equations of motion. From our full suite of simulated systems we find that a fraction ≃ 20 - 30 % of the MBH binaries that would otherwise stall are led to coalesce within a Hubble time. The corresponding coalescence timescale peaks around 300 Myr, while the eccentricity close to the plunge, albeit small, is non-negligible (≲ 0.1). We construct and discuss marginalised probability distributions of the main parameters involved and, in a companion paper of the series, we will use the results presented here to forecast the contribution of MBH triplets to the GW signal in the nHz regime probed by Pulsar Timing Array experiments.

  7. Path-integral derivation of black-hole radiance inside the de-Rham-Gabadadze-Tolley formulation of massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Arraut, Ivan [Institute of Theoretical Physics, Chinese Academy of Science, State Key Laboratory of Theoretical Physics, Beijing (China)

    2017-08-15

    If we apply the path-integral formulation in order to analyze the particle creation process of black holes inside the non-linear formulation of massive gravity, it is possible to demonstrate that the effect of the extra degrees of freedom is to deform the periodicity of the poles of the propagator in the complex t-plane. This might create the effect of extra particle creation process at scales where the extra degrees of freedom become relevant. For stationary solutions, depending on the values taken by the free parameters of the theory, the periodicity structure of the propagator reveal two effects. The first one is a shift on the positions of the pole of the propagator with respect to the GR case, affecting then the instant at which the particles are detected. The second one is the existence of branch points, affecting then the perception of particles. The branch point can be finite (including the zero order case) or infinite, depending on the free parameters of the theory. (orig.)

  8. Path-integral derivation of black-hole radiance inside the de-Rham-Gabadadze-Tolley formulation of massive gravity

    Science.gov (United States)

    Arraut, Ivan

    2017-08-01

    If we apply the path-integral formulation in order to analyze the particle creation process of black holes inside the non-linear formulation of massive gravity, it is possible to demonstrate that the effect of the extra degrees of freedom is to deform the periodicity of the poles of the propagator in the complex t-plane. This might create the effect of extra particle creation process at scales where the extra degrees of freedom become relevant. For stationary solutions, depending on the values taken by the free parameters of the theory, the periodicity structure of the propagator reveal two effects. The first one is a shift on the positions of the pole of the propagator with respect to the GR case, affecting then the instant at which the particles are detected. The second one is the existence of branch points, affecting then the perception of particles. The branch point can be finite (including the zero order case) or infinite, depending on the free parameters of the theory.

  9. Interaction of Massive Black Hole Binaries with Their Stellar Environment. II. Loss Cone Depletion and Binary Orbital Decay

    Science.gov (United States)

    Sesana, Alberto; Haardt, Francesco; Madau, Piero

    2007-05-01

    We study the long-term evolution of massive black hole binaries (MBHBs) at the centers of galaxies using detailed scattering experiments to solve the full three-body problem. Ambient stars drawn from an isotropic Maxwellian distribution unbound to the binary are ejected by the gravitational slingshot. We construct a minimal, hybrid model for the depletion of the loss cone and the orbital decay of the binary and show that secondary slingshots-stars returning on small-impact parameter orbits to have a second superelastic scattering with the MBHB-may considerably help the shrinking of the pair in the case of large binary mass ratios. In the absence of loss cone refilling by two-body relaxation or other processes, the mass ejected before the stalling of a MBHB is half the binary reduced mass. About 50% of the ejected stars are expelled in a ``burst'' lasting ~104 yr M1/46, where M6 is the binary mass in units of 106 Msolar. The loss cone is completely emptied in a few bulge crossing timescales, ~107 yr M1/46. Even in the absence of two-body relaxation or gas dynamical processes, unequal mass and/or eccentric binaries with M6>~0.1 can shrink to the gravitational wave emission regime in less than a Hubble time and are therefore ``safe'' targets for the planned Laser Interferometer Space Antenna.

  10. Behavior of quasinormal modes and Van der Waals-like phase transition of charged AdS black holes in massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Zou, De-Cheng; Yue, Ruihong [Yangzhou University, Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou (China); Liu, Yunqi [Huazhong University of Science and Technology, School of Physics, Wuhan (China)

    2017-06-15

    In this work, we utilize the quasinormal modes (QNMs) of a massless scalar perturbation to probe the Van der Waals-like small and large black holes (SBH/LBH) phase transition of charged topological Anti-de Sitter (AdS) black holes in four-dimensional massive gravity. We find that the signature of this SBH/LBH phase transition is detected in the isobaric as well as in the isothermal process. This further supports the idea that the QNMs can be an efficient tool to investigate the thermodynamical phase transition. (orig.)

  11. Low-mass black holes as the remnants of primordial black hole formation

    OpenAIRE

    Greene, Jenny E.

    2012-01-01

    This article documents our ongoing search for the elusive "intermediate-mass" black holes. These would bridge the gap between the approximately ten solar mass "stellar-mass" black holes that are the end-product of the life of a massive star, and the "supermassive" black holes with masses of millions to billions of solar masses found at the centers of massive galaxies. The discovery of black holes with intermediate mass is the key to understanding whether supermassive black holes can grow from...

  12. Low gamma radiation dose effect on germination and initial growing of black beans (Phaseolus vulgaris L.) seeds

    International Nuclear Information System (INIS)

    Jesus, Edgar F.O. de; Silva, Anderson de O. Melo; Marsico, Eliane T.

    2005-01-01

    In this work we analyze the effect of low gamma irradiation doses and low concentrations of sodium alginate on the germination and growing of black beans seeds. The seeds were obtained from an organic farmer at Nova Friburgo, Rio de Janeiro State. The seeds were submitted to radiation doses between 0 and 150 Gy with a Cobalt 60 source in a Gammacell Excel 220 Nordion Irradiator with a dose rate of 70 Gy/min. After germination the seeds were left to grow three weeks on a hydroponics system. The system used was the water culture with nutritive solution that was supplemented with the nutritional needs for plant grows. We also tested the influence of the sodium alginate on the plant grows. A 4% solution of sodium alginate in distilled water was irradiated with 120 kGy gamma ray dose. Concentrations of sodium alginate irradiated and non-irradiated varying from 50 to 500 μg/g were used in the hydroponics' solution. After three weeks the mass and the height of the plant were measured. Statistic analyses of he result with the SAS program show that there was no significant difference between the height and mass of seeds submitted different doses, but irradiated solution of sodium alginate with concentration of 400 and 500 μg/g present a significant difference on plant grow. (author)

  13. On the Possibility that Ultra-Light Boson haloes host and form Super-massive Black Holes

    Science.gov (United States)

    Avilez, Ana A.; Bernal, Tula; Padilla, Luis E.; Matos, Tonatiuh

    2018-03-01

    Several observations suggest the existence of super-massive black holes (SMBH) at the centres of galaxies. However, the mechanism under which these objects form remains non completely understood. In this work, we review an alternative mechanism of formation of galactic SMBHs from the collapse of a fraction of a dark matter (DM) halo made of an ultra-light scalar field (SF) whose critical mass of collapse is ˜1013M⊙ . Once the BH is formed, a long-living quasi-resonant SF configuration survives and plays the role of a central fraction of the galactic DM halo. In this work we construct a model with an ultra-light SF configuration laying in a Schwarzschild space-time to describe the centre of the DM halo hosting a SMBH in equilibrium, in the limit where self-gravitating effects can be neglected. We compute the induced stellar velocity dispersion in order to investigate the influence of the BH onto the velocity field of visible matter at the central galactic regions. We fit the empirical correlation between stellar velocity dispersions and masses of SMBHs considering two instances: the idealized case of DM dominated (DMD) systems, where the gravitational influence of baryons is neglected, and cases of real luminous galaxies (LGAL). In the DMD case, we found it is possible to reproduce the observed stellar velocity dispersions at the effective radius of systems hosting SMBHs of at most 108M⊙. In the LGAL case, we found that the baryons are crucial to reproduce the observed velocity dispersion.

  14. Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

    Science.gov (United States)

    Wang, Ran; Momjian, Emmanuel; Carilli, Chris L.; Wu, Xue-Bing; Fan, Xiaohui; Walter, Fabian; Strauss, Michael A.; Wang, Feige; Jiang, Linhua

    2017-02-01

    We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μJy beam-1 and a total flux density of 88 ± 19 μJy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be TB = (1.6 ± 1.2) × 107 K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

  15. Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ran; Wu, Xue-Bing; Jiang, Linhua [Kavli Institute of Astronomy and Astrophysics at Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China); Momjian, Emmanuel; Carilli, Chris L. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States); Fan, Xiaohui [Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Walter, Fabian [Max-Planck-Institute for Astronomy, Königsstuhl 17, D-69117 Heidelberg (Germany); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Wang, Feige [Department of Astronomy, School of Physics, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China)

    2017-02-01

    We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μ Jy beam{sup −1} and a total flux density of 88 ± 19 μ Jy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T {sub B} = (1.6 ± 1.2) × 10{sup 7} K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

  16. Growth and Yield of Black Locust (Robinia pseudoacacia L. Stands in Nyírség Growing Region (North-East Hungary

    Directory of Open Access Journals (Sweden)

    Károly Rédei

    2014-06-01

    Full Text Available Background and Purpose: In Hungary the black locust (Robinia pseudoacacia L. can be considered as the most important fast-growing stand-forming exotic tree species. Due to its favourite growing technological characteristics as well as its wood utilization possibilities the present area occupied by black locust stands amounts to 460 thousand hectares. Of its growing districts Nyírség (North-East Hungary has a distinguished importance where the area of black locust stands is appr. 22 700 hectares. The Nyírség region can also be considered as one of the best black locust growing regions in the Carpathian basin. To determine their growth rate and yield as exact as possible a local numerical yield table has been constructed on the basis of surveys of the experimental plots established in pure, managed black locust stands. Material and Methods: The local black locust yield table was constructed from data gathered on 105 sampling plots with average area of 1 000 m2. The total area of the experimental plots was 9.295 ha. In the course of the stand surveys the key stand characteristics were measured, and then, on the basis of data collected, were calculated the average height, diameter (DBH, volume, basal area and stem number given separately for the main (remaining, secondary (removal and total stands per hectare. Results and Conclusion: Black locust yield table presented in this paper is the first local one in the history of the Hungarian black locust research. The programmable editing procedure allows extension and formal change of information content of the yield table according to different demands. This type of yield tables (standards somewhat reflects the local growing-technological (forest tending characteristics better way, on the other hand refer to the trend of quality and quantity changing of black locust stands growing in a given area.

  17. Testing the Relevance of Mergers and Enviroment for the Fastest Growing Black Holes in the Most Intensely Star Forming Galaxies

    Science.gov (United States)

    Trakhtenbrot, Benny

    2017-08-01

    We propose a pilot study to explore the role of major galaxy mergers in shaping the early history of the largest super-massive black holes (SMBHs). We will use HST's high sensitivity and resolution to map the stellar content of the host galaxies and close environments of six very luminous QSOs at z 4.8, for which we have obtained a rich collection of ground- and space-based data, including new ALMA data that probe the hosts' gas. Our previous analysis of these systems clearly shows fast SMBH and host galaxy growth, with some systems exhibiting extremely high star formation rates, SFR >2000 M_sol/yr, suggestive of merger-driven activity. Our new ALMA data show evidence for mergers among some of the lower-SFR objects, while presenting no clear evidence for mergers among some of the extreme SFR sources. The deep HST/WFC3-IR imaging data will allow us to look for two types of merger indicators: (1) disturbed star-forming sub-structures within the host galaxies of the QSOs, and (2) close, possibly interacting companions. Thus, the proposed HST observations will provide the only missing ingredient in our long-term effort to identify the dominant mechanism driving the early epoch of SMBH-host (co-)evolution. If successful, the combined HST and ALMA effort will be extended to a larger sample, based on our on-going ALMA cycle-4 observations of 12 additional systems.

  18. Can White children grow up to be Black? Children’s reasoning about the stability of emotion and race

    Science.gov (United States)

    Roberts, Steven O.; Gelman, Susan A.

    2016-01-01

    Recent research questions whether children conceptualize race as stable. We examined participants' beliefs about the relative stability of race and emotion, a temporary feature. Participants were White adults and children ages 5–6 and 9–10 (Study 1) and racial minority children ages 5–6 (Study 2). Participants were presented with target children who were happy or angry, and Black or White, and asked to indicate which of two adults (a race- but not emotion-match or an emotion- but not race-match) each child would grow up to be. White adults, White 9- to 10-year-olds, and racial minority 5- to 6-year-olds selected race-matches, whereas White 5- to 6-year-olds selected race- and emotion-matches equally. These data suggest that beliefs about racial stability vary by age and social group. PMID:27148779

  19. Stellar-mass black holes in young massive and open stellar clusters and their role in gravitational-wave generation - II

    Science.gov (United States)

    Banerjee, Sambaran

    2018-01-01

    The study of stellar-remnant black holes (BH) in dense stellar clusters is now in the spotlight, especially due to their intrinsic ability to form binary black holes (BBH) through dynamical encounters, which potentially coalesce via gravitational-wave (GW) radiation. In this work, which is a continuation from a recent study (Paper I), additional models of compact stellar clusters with initial masses ≲ 105 M⊙ and also those with small fractions of primordial binaries (≲ 10 per cent) are evolved for long term, applying the direct N-body approach, assuming state-of-the-art stellar-wind and remnant-formation prescriptions. That way, a substantially broader range of computed models than that in Paper I is achieved. As in Paper I, the general-relativistic BBH mergers continue to be mostly mediated by triples that are bound to the clusters rather than happen among the ejected BBHs. In fact, the number of such in situ BBH mergers, per cluster, tends to increase significantly with the introduction of a small population of primordial binaries. Despite the presence of massive primordial binaries, the merging BBHs, especially the in situ ones, are found to be exclusively dynamically assembled and hence would be spin-orbit misaligned. The BBHs typically traverse through both the LISA's and the LIGO's detection bands, being audible to both instruments. The 'dynamical heating' of the BHs keeps the electron-capture-supernova (ECS) neutron stars (NS) from effectively mass segregating and participating in exchange interactions; the dynamically active BHs would also exchange into any NS binary within ≲1 Gyr. Such young massive and open clusters have the potential to contribute to the dynamical BBH merger detection rate to a similar extent as their more massive globular-cluster counterparts.

  20. Enhanced activity of massive black holes by stellar capture assisted by a self-gravitating accretion disc

    Czech Academy of Sciences Publication Activity Database

    Karas, Vladimír; Šubr, L.

    2007-01-01

    Roč. 470, č. 1 (2007), s. 11-19 ISSN 0004-6361 R&D Projects: GA ČR GA205/07/0052; GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : black hole physics * accretion Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.259, year: 2007

  1. Enhancing the rate of tidal disruptions of stars by a self-gravitating disc around a massive central black hole

    Directory of Open Access Journals (Sweden)

    Šubr L.

    2012-12-01

    Full Text Available We further study the idea that a self-gravitating accretion disc around a supermassive black hole can increase the rate of gradual orbital decay of stellar trajectories (and hence tidal disruption events by setting some stars on eccentric trajectories. Cooperation between the gravitational field of the disc and the dissipative environment can provide a mechanism explaining the origin of stars that become bound tightly to the central black hole. We examine this process as a function of the black hole mass and conclude that it is most efficient for intermediate central masses of the order of ∼ 104Mʘ. Members of the cluster experience the stage of orbital decay via collisions with an accretion disc and by other dissipative processes, such as tidal effects, dynamical friction and the emission of gravitational waves. Our attention is concentrated on the region of gravitational dominance of the central body. Mutual interaction between stars and the surrounding environment establishes a non-spherical shape and anisotropy of the nuclear cluster. In some cases, the stellar sub-system acquires ring-type geometry. Stars of the nuclear cluster undergo a tidal disruption event as they plunge below the tidal radius of the supermassive black hole.

  2. Post-Newtonian evolution of massive black hole triplets in galactic nuclei - III. A robust lower limit to the nHz stochastic background of gravitational waves

    Science.gov (United States)

    Bonetti, Matteo; Sesana, Alberto; Barausse, Enrico; Haardt, Francesco

    2018-04-01

    Inspiraling massive black-hole binaries (MBHBs) forming in the aftermath of galaxy mergers are expected to be the loudest gravitational-wave (GW) sources relevant for pulsar-timing arrays (PTAs) at nHz frequencies. The incoherent overlap of signals from a cosmic population of MBHBs gives rise to a stochastic GW background (GWB) with characteristic strain around hc ˜ 10-15 at a reference frequency of 1 yr-1, although uncertainties around this value are large. Current PTAs are piercing into the GW amplitude range predicted by MBHB-population models, but no detection has been reported so far. To assess the future success prospects of PTA experiments, it is therefore important to estimate the minimum GWB level consistent with our current understanding of the formation and evolution of galaxies and massive black holes (MBHs). To this purpose, we couple a semianalytic model of galaxy evolution and an extensive study of the statistical outcome of triple MBH interactions. We show that even in the most pessimistic scenario where all MBHBs stall before entering the GW-dominated regime, triple interactions resulting from subsequent galaxy mergers inevitably drive a considerable fraction of the MBHB population to coalescence. At frequencies relevant for PTA, the resulting GWB is only a factor of 2-to-3 suppressed compared to a fiducial model where binaries are allowed to merge over Gyr timescales. Coupled with current estimates of the expected GWB amplitude range, our findings suggest that the minimum GWB from cosmic MBHBs is unlikely to be lower than hc ˜ 10-16 (at f = 1 yr-1), well within the expected sensitivity of projected PTAs based on future observations with FAST, MeerKAT and SKA.

  3. Jet Physics of Accreting Super-Massive Black Holes in the Era of the Fermi Gamma-ray Space Telescope

    Directory of Open Access Journals (Sweden)

    Filippo D'Ammando

    2017-11-01

    Full Text Available The Fermi Gamma-ray Space Telescope with its main instrument on-board, the Large Area Telescope (LAT, opened a new era in the study of high-energy emission from Active Galactic Nuclei (AGN. When combined with contemporaneous ground- and space-based observations, Fermi-LAT achieves its full capability to characterize the jet structure and the emission mechanisms at work in radio-loud AGN with different black hole mass and accretion rate, from flat spectrum radio quasars to narrow-line Seyfert 1 (NLSy1 galaxies. Here, I discuss important findings regarding the blazar population included in the third LAT catalog of AGN and the γ-ray emitting NLSy1. Moreover, the detection of blazars at redshift beyond three in γ rays allows us to constrain the growth and evolution of heavy black holes over cosmic time, suggesting that the radio-loud phase may be important for a fast black hole growth in the early Universe. Finally, results on extragalactic objects from the third catalog of hard LAT sources are presented.

  4. Jet Physics of Accreting Super-Massive Black Holes in the Era of the Fermi Gamma-ray Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    D' Ammando, Filippo, E-mail: dammando@ira.inaf.it [Dipartimento di Fisica e Astronomia, Universitá di Bologna, Bologna (Italy); Istituto di Radioastronomia (INAF), Bologna (Italy)

    2017-11-28

    The Fermi Gamma-ray Space Telescope with its main instrument on-board, the Large Area Telescope (LAT), opened a new era in the study of high-energy emission from Active Galactic Nuclei (AGN). When combined with contemporaneous ground- and space-based observations, Fermi-LAT achieves its full capability to characterize the jet structure and the emission mechanisms at work in radio-loud AGN with different black hole mass and accretion rate, from flat spectrum radio quasars to narrow-line Seyfert 1 (NLSy1) galaxies. Here, I discuss important findings regarding the blazar population included in the third LAT catalog of AGN and the γ-ray emitting NLSy1. Moreover, the detection of blazars at redshift beyond three in γ rays allows us to constrain the growth and evolution of heavy black holes over cosmic time, suggesting that the radio-loud phase may be important for a fast black hole growth in the early Universe. Finally, results on extragalactic objects from the third catalog of hard LAT sources are presented.

  5. THE X-RAY SPECTRUM OF THE COOLING-FLOW QUASAR H1821+643: A MASSIVE BLACK HOLE FEEDING OFF THE INTRACLUSTER MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Christopher S.; Lohfink, Anne M. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Babul, Arif [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8P 5C2 (Canada); Fabian, Andrew C.; Russell, Helen R.; Walker, Stephen A. [Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Hlavacek-Larrondo, Julie, E-mail: chris@astro.umd.edu [Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7 (Canada)

    2014-09-10

    We present a deep Suzaku observation of H1821+643, an extremely rare example of a powerful quasar hosted by the central massive galaxy of a rich cooling-core cluster of galaxies. Informed by previous Chandra studies of the cluster, we achieve a spectral separation of emission from the active galactic nucleus (AGN) and the intracluster medium (ICM). With a high degree of confidence, we identify the signatures of X-ray reflection/reprocessing by cold and slowly moving material in the AGN's immediate environment. The iron abundance of this matter is found to be significantly sub-solar (Z ≈ 0.4 Z {sub ☉}), an unusual finding for powerful AGN but in line with the idea that this quasar is feeding from the ICM via a Compton-induced cooling flow. We also find a subtle soft excess that can be described phenomenologically (with an additional blackbody component) or as ionized X-ray reflection from the inner regions of a high inclination (i ≈ 57°) accretion disk around a spinning (a > 0.4) black hole. We describe how the ionization state of the accretion disk can be used to constrain the Eddington fraction of the source. Applying these arguments to our spectrum implies an Eddington fraction of 0.25-0.5, with an associated black hole mass of 3--6×10{sup 9} M{sub ⊙}.

  6. Black holes

    International Nuclear Information System (INIS)

    Feast, M.W.

    1981-01-01

    This article deals with two questions, namely whether it is possible for black holes to exist, and if the answer is yes, whether we have found any yet. In deciding whether black holes can exist or not the central role in the shaping of our universe played by the forse of gravity is discussed, and in deciding whether we are likely to find black holes in the universe the author looks at the way stars evolve, as well as white dwarfs and neutron stars. He also discusses the problem how to detect a black hole, possible black holes, a southern black hole, massive black holes, as well as why black holes are studied

  7. Using LISA extreme-mass-ratio inspiral sources to test off-Kerr deviations in the geometry of massive black holes

    International Nuclear Information System (INIS)

    Barack, Leor; Cutler, Curt

    2007-01-01

    Inspirals of stellar-mass compact objects (COs) into ∼10 6 M · black holes are especially interesting sources of gravitational waves for the planned Laser Interferometer Space Antenna (LISA). The orbits of these extreme-mass-ratio inspirals (EMRIs) are highly relativistic, displaying extreme versions of both perihelion precession and Lense-Thirring precession of the orbital plane. We investigate the question of whether the emitted waveforms can be used to strongly constrain the geometry of the central massive object, and in essence check that it corresponds to a Kerr black hole (BH). For a Kerr BH, all multipole moments of the spacetime have a simple, unique relation to M and S, the BH mass, and spin; in particular, the spacetime's mass quadrupole moment Q is given by Q=-S 2 /M. Here we treat Q as an additional parameter, independent of S and M, and ask how well observation can constrain its difference from the Kerr value. This was already estimated by Ryan, but for the simplified case of circular, equatorial orbits, and Ryan also neglected the signal modulations arising from the motion of the LISA satellites. We consider generic orbits and include the modulations due to the satellite motions. For this analysis, we use a family of approximate (basically post-Newtonian) waveforms, which represent the full parameter space of EMRI sources, and which exhibit the main qualitative features of true, general relativistic waveforms. We extend this parameter space to include (in an approximate manner) an arbitrary value of Q, and then construct the Fisher information matrix for the extended parameter space. By inverting the Fisher matrix, we estimate how accurately Q could be extracted from LISA observations of EMRIs. For 1 yr of coherent data from the inspiral of a 10M · black hole into rotating black holes of masses 10 5.5 M · , 10 6 M · , or 10 6.5 M · , we find Δ(Q/M 3 )∼10 -4 , 10 -3 , or 10 -2 , respectively (assuming total signal-to-noise ratio of 100

  8. The Buffering Hypothesis: Growing Diversity and Declining Black-White Segregation in America’s Cities, Suburbs, and Small Towns?

    Directory of Open Access Journals (Sweden)

    Domenico Parisi

    2015-03-01

    Full Text Available The conventional wisdom is that racial diversity promotes positive race relations and reduces racial residential segregation between blacks and whites. We use data from the 1990–2010 decennial censuses and 2007–2011 ACS to test this so-called “buffering hypothesis.” We identify cities, suburbs, and small towns that are virtually all white, all black, all Asian, all Hispanic, and everything in between. The results show that the most racially diverse places—those with all four racial groups (white, black, Hispanic, and Asian present—had the lowest black-white levels of segregation in 2010. Black-white segregation also declined most rapidly in the most racially diverse places and in places that experienced the largest recent increases in diversity. Support for the buffering hypothesis, however, is counterbalanced by continuing high segregation across cities and communities and by rapid white depopulation in the most rapidly diversifying communities. We argue for a new, spatially inclusive perspective on racial residential segregation.

  9. A YOUNG MASSIVE STELLAR POPULATION AROUND THE INTERMEDIATE-MASS BLACK HOLE ESO 243-49 HLX-1

    International Nuclear Information System (INIS)

    Farrell, S. A.; Servillat, M.; Pforr, J.; Maraston, C.; Maccarone, T. J.; Knigge, C.; Godet, O.; Webb, N. A.; Barret, D.; Belmont, R.; Gosling, A. J.; Wiersema, K.

    2012-01-01

    We present Hubble Space Telescope and simultaneous Swift X-ray Telescope observations of the strongest candidate intermediate-mass black hole (IMBH) ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disk models, but is well described by a model comprised of an irradiated accretion disk plus a ∼10 6 M ☉ stellar population. The age of the population cannot be uniquely constrained, with both young and old stellar populations allowed. However, the old solution requires excessive disk reprocessing and an extremely small disk, so we favor the young solution (∼13 Myr). In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy suggest that a gas-rich minor merger may have taken place less than ∼200 Myr ago. Such a merger event would explain the presence of the IMBH and the young stellar population.

  10. Massive Gravity

    Directory of Open Access Journals (Sweden)

    Claudia de Rham

    2014-08-01

    Full Text Available We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP, cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alternative and related models of massive gravity such as new massive gravity, Lorentz-violating massive gravity and non-local massive gravity.

  11. Search for the signatures of a new-born black hole from the collapse of a supra-massive millisecond magnetar in short GRB light curves

    Science.gov (United States)

    Zhang, Q.; Lei, W. H.; Zhang, B. B.; Chen, W.; Xiong, S. L.; Song, L. M.

    2018-03-01

    `Internal plateau' followed by a sharp decay is commonly seen in short gamma-ray burst (GRB) light curves. The plateau component is usually interpreted as the dipole emission from a supra-massive magnetar, and the sharp decay may imply the collapse of the magnetar to a black hole (BH). Fall-back accretion on to the new-born BH could produce long-lasting activities via the Blandford-Znajek (BZ) process. The magnetic flux accumulated near the BH would be confined by the accretion discs for a period of time. As the accretion rate decreases, the magnetic flux is strong enough to obstruct gas infall, leading to a magnetically arrested disc. Within this scenario, we show that the BZ process could produce two types of typical X-ray light curves: type I exhibits a long-lasting plateau, followed by a power-law (PL) decay with slopes ranging from 5/3 to 40/9; type II shows roughly a single PL decay with a slope of 5/3. The former requires low magnetic field strength, while the latter corresponds to relatively high values. We search for such signatures of the new-born BH from a sample of short GRBs with an internal plateau, and find two candidates: GRB 101219A and GRB 160821B, corresponding to type II and type I light curves, respectively. It is shown that our model can explain the data very well.

  12. A full general relativistic neutrino radiation-hydrodynamics simulation of a collapsing very massive star and the formation of a black hole

    Science.gov (United States)

    Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya; Thielemann, Friedrich-Karl

    2018-04-01

    We study the final fate of a very massive star by performing full general relativistic (GR), three-dimensional (3D) simulation with three-flavor multi-energy neutrino transport. Utilizing a 70 solar mass zero metallicity progenitor, we self-consistently follow the radiation-hydrodynamics from the onset of gravitational core-collapse until the second collapse of the proto-neutron star (PNS), leading to black hole (BH) formation. Our results show that the BH formation occurs at a post-bounce time of Tpb ˜ 300 ms for the 70 M⊙ star. This is significantly earlier than those in the literature where lower mass progenitors were employed. At a few ˜10 ms before BH formation, we find that the stalled bounce shock is revived by intense neutrino heating from the very hot PNS, which is aided by violent convection behind the shock. In the context of 3D-GR core-collapse modeling with multi-energy neutrino transport, our numerical results present the first evidence to validate a fallback BH formation scenario of the 70M⊙ star.

  13. The gravitational wave background from massive black hole binaries in Illustris: spectral features and time to detection with pulsar timing arrays

    Science.gov (United States)

    Kelley, Luke Zoltan; Blecha, Laura; Hernquist, Lars; Sesana, Alberto; Taylor, Stephen R.

    2017-11-01

    Pulsar timing arrays (PTAs) around the world are using the incredible consistency of millisecond pulsars to measure low-frequency gravitational waves from (super)massive black hole (MBH) binaries. We use comprehensive MBH merger models based on cosmological hydrodynamic simulations to predict the spectrum of the stochastic gravitational wave background (GWB). We use real time-of-arrival specifications from the European, NANOGrav, Parkes, and International PTA (IPTA) to calculate realistic times to detection of the GWB across a wide range of model parameters. In addition to exploring the parameter space of environmental hardening processes (in particular: stellar scattering efficiencies), we have expanded our models to include eccentric binary evolution which can have a strong effect on the GWB spectrum. Our models show that strong stellar scattering and high characteristic eccentricities enhance the GWB strain amplitude near the PTA-sensitive `sweet-spot' (near the frequency f = 1 yr-1), slightly improving detection prospects in these cases. While the GWB amplitude is degenerate between cosmological and environmental parameters, the location of a spectral turnover at low frequencies (f ≲ 0.1 yr-1) is strongly indicative of environmental coupling. At high frequencies (f ≳ 1 yr-1), the GWB spectral index can be used to infer the number density of sources and possibly their eccentricity distribution. Even with merger models that use pessimistic environmental and eccentricity parameters, if the current rate of PTA expansion continues, we find that the IPTA is highly likely to make a detection within about 10 yr.

  14. Black holes and galaxy formation

    CERN Document Server

    Propst, Raphael J

    2010-01-01

    Galaxies are the basic unit of cosmology. The study of galaxy formation is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning. The physics of galaxy formation is complicated because it deals with the dynamics of stars, thermodynamics of gas and energy production of stars. A black hole is a massive object whose gravitational field is so intense that it prevents any form of matter or radiation to escape. It is hypothesized that the most massive galaxies in the universe- "elliptical galaxies"- grow simultaneously with the supermassive black holes at their centers, giving us much stronger evidence that black holes control galaxy formation. This book reviews new evidence in the field.

  15. On Black Hole Stability in Critical Gravities

    Science.gov (United States)

    Liu, Haishan; Lü, H.; Luo, Mingxing

    We consider extended cosmological gravities with Ricci tensor and scalar squared terms in diverse dimensions. These theories admit solutions of Einstein metrics, including the Schwarzschild-Tangherlini AdS black holes, whose mass and entropy vanish at the critical point. We perform linearized analysis around the black holes and show that in general the spectrum consists of the usual spin-2 massless and ghost massive modes. We demonstrate that there is no exponentially-growing tachyon mode in the black holes. At the critical point, the massless spin-2 modes have zero energy whilst the massive spin-2 modes are replaced by the log modes. There always exist certain linear combination of massless and log modes that has negative energy. Thus the stability of the black holes requires that the log modes to be truncated out by the boundary condition.

  16. Gravitational waves from a compact star in a circular, inspiral orbit, in the equatorial plane of a massive, spinning black hole, as observed by LISA

    International Nuclear Information System (INIS)

    Finn, Lee Samuel; Thorne, Kip S.

    2000-01-01

    Results are presented from high-precision computations of the orbital evolution and emitted gravitational waves for a stellar-mass object spiraling into a massive black hole in a slowly shrinking, circular, equatorial orbit. The focus of these computations is inspiral near the innermost stable circular orbit (isco) -- more particularly, on orbits for which the angular velocity Ω is 0.03∼ isco ≤1.0. The computations are based on the Teuksolsky-Sasaki-Nakamura formalism, and the results are tabulated in a set of functions that are of order unity and represent relativistic corrections to low-orbital-velocity formulas. These tables can form a foundation for future design studies for the LISA space-based gravitational-wave mission. A first survey of applications to LISA is presented: Signal to noise ratios S/N are computed and graphed as functions of the time-evolving gravitational-wave frequency for the lowest three harmonics of the orbital period, and for various representative values of the hole's mass M and spin a and the inspiraling object's mass μ, with the distance to Earth chosen to be r o =1 Gpc. These S/N's show a very strong dependence on the black-hole spin, as well as on M and μ. Graphs are presented showing the range of the {M,a,μ} parameter space, for which S/N>10 at r 0 =1 Gpc during the last year of inspiral. The hole's spin a has a factor of ∼10 influence on the range of M (at fixed μ) for which S/N>10, and the presence or absence of a white-dwarf--binary background has a factor of ∼3 influence. A comparison with predicted event rates shows strong promise for detecting these waves, but not beyond about 1 Gpc if the inspiraling object is a white dwarf or neutron star. This argues for a modest lowering of LISA's noise floor. A brief discussion is given of the prospects for extracting information from the observed waves

  17. Quantifying the growing season dynamics and phenology of a boreal black spruce wildfire chronosequence: Coupling field measurements with MODIS

    Science.gov (United States)

    Serbin, S. P.; Ahl, D. E.; Gower, S. T.

    2007-12-01

    The boreal forest is the second largest forested biome and the vast area and large carbon stores in the soil makes these forests important to the global carbon, water and energy cycles. Analysis of global coverage, coarse resolution satellite Vegetation Index (VI) data have provided considerable information on the seasonal cycles of vegetation in the mid-to high-latitudes, including the boreal forest, with evidence of an increase in the magnitude of vegetation greenness and a lengthening of the active growing season, which has been attributed to climate warming. However, boreal forests are prone to extensive wildfire disturbance that influence canopy dynamics (i.e. species composition, LAI, and phenology) and separating the direct affect of warming from the indirect affect of increased wildfire frequency on the patterns of boreal phenology and seasonal greeness requires further analysis coupled to ground measurements. In this research we address the need for detailed information on the growing season dynamics and phenological patterns of boreal vegetation. We evaluate whether MODIS reflectance data can resolve small inter-annual variations in canopy phenology and growing season dynamics of boreal forests. We quantified the seasonality and inter-annual differences of the overstory and understory vegetation by optically measuring the LAI and light harvesting potential (FPAR) during the 2004-2006 growing seasons. An automated continuously operating system is used to monitor growing season PAR transmittance. We focused on a boreal wildfire chronosequence of sites comprising a range of forest ages (1-154 years since fire) to quantify the differences in vegetation dynamics and phenology between the deciduous/mixed and coniferous forests. The spatial and temporal characteristics of LAI / FPAR within the chronosequence were examined by comparing both the in situ measurements and the relevant MODIS products. A statistical curve fitting procedure is used to derive the key

  18. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    International Nuclear Information System (INIS)

    Prodan, Snezana; Antonini, Fabio; Perets, Hagai B.

    2015-01-01

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center

  19. Seeding black holes in cosmological simulations

    Science.gov (United States)

    Taylor, P.; Kobayashi, C.

    2014-08-01

    We present a new model for the formation of black holes in cosmological simulations, motivated by the first star formation. Black holes form from high density peaks of primordial gas, and grow via both gas accretion and mergers. Massive black holes heat the surrounding material, suppressing star formation at the centres of galaxies, and driving galactic winds. We perform an investigation into the physical effects of the model parameters, and obtain a `best' set of these parameters by comparing the outcome of simulations to observations. With this best set, we successfully reproduce the cosmic star formation rate history, black hole mass-velocity dispersion relation, and the size-velocity dispersion relation of galaxies. The black hole seed mass is ˜103 M⊙, which is orders of magnitude smaller than that which has been used in previous cosmological simulations with active galactic nuclei, but suggests that the origin of the seed black holes is the death of Population III stars.

  20. Massive Gravity

    OpenAIRE

    de Rham, Claudia

    2014-01-01

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

  1. Thermodynamics inducing massive particles' tunneling and cosmic censorship

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Baocheng [Chinese Academy of Sciences, State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Wuhan (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Cai, Qing-yu [Chinese Academy of Sciences, State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Wuhan (China); Zhan, Ming-sheng [Chinese Academy of Sciences, State Key Laboratory of Magnetic Resonances and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Wuhan (China); Chinese Academy of Sciences, Center for Cold Atom Physics, Wuhan (China)

    2010-08-15

    By calculating the change of entropy, we prove that the first law of black hole thermodynamics leads to the tunneling probability of massive particles through the horizon, including the tunneling probability of massive charged particles from the Reissner-Nordstroem black hole and the Kerr-Newman black hole. Novelly, we find the trajectories of massive particles are close to that of massless particles near the horizon, although the trajectories of massive charged particles may be affected by electromagnetic forces. We show that Hawking radiation as massive particles tunneling does not lead to violation of the weak cosmic-censorship conjecture. (orig.)

  2. What is black hole?

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. What is black hole? Possible end phase of a star: A star is a massive, luminous ball of plasma having continuous nuclear burning. Star exhausts nuclear fuel →. White Dwarf, Neutron Star, Black Hole. Black hole's gravitational field is so powerful that even ...

  3. Coagulation management in massive bleeding.

    Science.gov (United States)

    Griffee, Matthew J; Deloughery, Thomas G; Thorborg, Per A

    2010-04-01

    To update readers on recent literature regarding treatment of coagulopathy for patients with life-threatening bleeding, highlighting emerging therapeutic options, controversial topics, and ongoing clinical trials. Massive transfusion protocols featuring immediate availability of blood products and multidisciplinary communication reduce mortality and conserve resources. There is a growing consensus that immediate administration of plasma and platelet units in a 1: 1: 1 ratio with red cell units reduces early mortality. Lyophilized and recombinant blood product components may have advantages over traditional blood products in certain clinical circumstances. Massive transfusion protocols standardize treatment of the coagulopathy of massive bleeding, leading to rapid restoration of hemostasis and decrease in early mortality.

  4. Growing Black Holes: Accretion in a Cosmological Context Proceedings of the MPA/ESO/MPE/USM Joint Astronomy Conference Held at Garching, Germany, 21-25 June 2004

    CERN Document Server

    Merloni, Andrea; Sunyaev, Rashid A

    2005-01-01

    Supermassive black holes are now believed to play an important role in the evolution of the Universe. Every respectable galaxy hosts in its center a black hole that appears to regulate the growth of the galaxy itself. In this book, leading experts in the field review the most recent theoretical and observational results on the following topics: * formation and growth of the first black holes in the Universe and their role in the formation and evolution of galaxies * the physics of black-hole accretion and the production of relativistic jets * binary black-hole mergers and gravitational radiation. Theoretical work is supplemented by the most recent exciting results from space and ground based observatories. This volume is useful research and reference tool for the entire astrophysical community.

  5. True and standardized total tract phosphorus digestibility in canola meals from Brassica napus black and Brassica juncea yellow fed to growing pigs.

    Science.gov (United States)

    Adhikari, P A; Heo, J M; Nyachoti, C M

    2015-01-01

    The aim was to determine the true total tract digestibility (TTTD) and standardized total tract digestibility (STTD) of P in canola meals from Brassica napus black (BNB) and Brassica juncea yellow (BJY) fed to growing pigs. Fifty-four barrows with an initial BW of 19.9 ± 0.22 kg (mean ± SEM) were allocated in 3 consecutive blocks to 1 of 9 dietary treatments in a randomized complete block design to give 6 replicate pigs per diet. Dietary treatments were cornstarch based with increasing concentrations of P, that is, 0.8, 1.6, 2.4, and 3.3 g/kg (as-fed basis) from either BNB or BJY as the sole source of P and a gelatin-based P-free diet. Limestone was added to maintain a Ca:total P ratio of 1.2:1 in all diets. All diets contained titanium dioxide (3 g/kg) as an indigestible marker. Daily feed allowance was calculated to supply 2.6 times the maintenance energy requirement based on the BW at the beginning of each period and offered in 2 equal portions at 0800 and 1600 h as a dry mash. Pigs were individually housed in metabolism crates and fed experimental diets for 16 d, including 9 d for adaptation to feed and 5 d for total but separate collection of feces and urine. The apparent total tract digestibility values of P increased from 19.0 to 30.0% for BNB and from 17.3 to 28.3% for BJY as the dietary P content increased from 0.8 to 3.3 g/kg DM. The TTTD of P was determined using the regression analysis as dietary P content increased from 0.8 to 3.3 g/kg whereas the STTD of P was calculated for the diet with the highest P content (i.e., 3.3 g/kg, as-fed basis) using the P-free diet to estimate endogenous P losses (EPL). The total and basal EPL estimates obtained with regression analysis and the P-free diet were 665 ± 0.03 and 209 ± 96 mg/kg DMI, respectively. The TTTD of P was 33.3 and 32.0% in BNB and BJY, respectively. Respective STTD values were 31.0 and 28.3%. The results indicated that the TTTD and STTD of P were comparable in the 2 canola meals from BNB and BJY

  6. Discovery of a 7 mHz X-Ray Quasi-Periodic Oscillation from the Most Massive Stellar-Mass Black Hole IC 10 X-1

    Science.gov (United States)

    Pasham, Dheeraj R.; Strohmayer, Tod E.; Mushotzky, Richard F.

    2013-01-01

    We report the discovery with XMM-Newton of an approx.. = 7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33 sigma confidence level and has a fractional amplitude (% rms) and a quality factor, Q is identical with nu/delta nu, of approx. = 11 and 4, respectively. The overall X-ray (0.3-10.0 keV) power spectrum in the frequency range 0.0001-0.1 Hz can be described by a power-law with an index of approx. = -2, and a QPO at 7 mHz. At frequencies approx. > 0.02 Hz there is no evidence for significant variability. The fractional amplitude (rms) of the QPO is roughly energy-independent in the energy range of 0.3-1.5 keV. Above 1.5 keV the low signal-to-noise ratio of the data does not allow us to detect the QPO. By directly comparing these properties with the wide range of QPOs currently known from accreting black hole and neutron stars, we suggest that the 7 mHz QPO of IC 10 X-1 may be linked to one of the following three categories of QPOs: (1) the "heartbeat" mHz QPOs of the black hole sources GRS 1915+105 and IGR J17091-3624, or (2) the 0.6-2.4 Hz "dipper QPOs" of high-inclination neutron star systems, or (3) the mHz QPOs of Cygnus X-3.

  7. Shoot water relations of mature black spruce families displaying a genotype x environment interaction in growth rate. I. Family and site effects over three growing seasons

    Science.gov (United States)

    Kurt H. Johnsen; John E Major

    1999-01-01

    Pressure-volume curves were determined for black spruce (Picea mariana (Mill.) BSP) trees from four full-sib families. During the first two years, trees were measured from a plantation on a dry site. In the third year, trees were sampled from the dry site and a wet site. Diurnal measurements of shoot water potential allowed in situ ...

  8. Low gamma radiation dose effect on germination and initial growing of black beans (Phaseolus vulgaris L.) seeds; Efeito de baixas doses de radiacao gama na germinacao de sementes de feijao (Phaseolus vulgaris L.)

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Edgar F.O. de; Silva, Anderson de O. Melo [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Lab. de Instrumentacao Nuclear]. E-mail: edgar@lin.ufrj.br; Marsico, Eliane T. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Faculdade de Veterinaria. Dept. de Tecnologia de Alimentos]. E-mail: elianee@vm.uff.br

    2005-07-01

    In this work we analyze the effect of low gamma irradiation doses and low concentrations of sodium alginate on the germination and growing of black beans seeds. The seeds were obtained from an organic farmer at Nova Friburgo, Rio de Janeiro State. The seeds were submitted to radiation doses between 0 and 150 Gy with a Cobalt 60 source in a Gammacell Excel 220 Nordion Irradiator with a dose rate of 70 Gy/min. After germination the seeds were left to grow three weeks on a hydroponics system. The system used was the water culture with nutritive solution that was supplemented with the nutritional needs for plant grows. We also tested the influence of the sodium alginate on the plant grows. A 4% solution of sodium alginate in distilled water was irradiated with 120 kGy gamma ray dose. Concentrations of sodium alginate irradiated and non-irradiated varying from 50 to 500 {mu}g/g were used in the hydroponics' solution. After three weeks the mass and the height of the plant were measured. Statistic analyses of he result with the SAS program show that there was no significant difference between the height and mass of seeds submitted different doses, but irradiated solution of sodium alginate with concentration of 400 and 500 {mu}g/g present a significant difference on plant grow. (author)

  9. Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers.

    Science.gov (United States)

    Mayer, L; Kazantzidis, S; Escala, A; Callegari, S

    2010-08-26

    Observations of distant quasars indicate that supermassive black holes of billions of solar masses already existed less than a billion years after the Big Bang. Models in which the 'seeds' of such black holes form by the collapse of primordial metal-free stars cannot explain the rapid appearance of these supermassive black holes because gas accretion is not sufficiently efficient. Alternatively, these black holes may form by direct collapse of gas within isolated protogalaxies, but current models require idealized conditions, such as metal-free gas, to prevent cooling and star formation from consuming the gas reservoir. Here we report simulations showing that mergers between massive protogalaxies naturally produce the conditions for direct collapse into a supermassive black hole with no need to suppress cooling and star formation. Merger-driven gas inflows give rise to an unstable, massive nuclear gas disk of a few billion solar masses, which funnels more than 10(8) solar masses of gas to a sub-parsec-scale gas cloud in only 100,000 years. The cloud undergoes gravitational collapse, which eventually leads to the formation of a massive black hole. The black hole can subsequently grow to a billion solar masses on timescales of about 10(8) years by accreting gas from the surrounding disk.

  10. The Destructive Birth of Massive Stars and Massive Star Clusters

    Science.gov (United States)

    Rosen, Anna; Krumholz, Mark; McKee, Christopher F.; Klein, Richard I.; Ramirez-Ruiz, Enrico

    2017-01-01

    Massive stars play an essential role in the Universe. They are rare, yet the energy and momentum they inject into the interstellar medium with their intense radiation fields dwarfs the contribution by their vastly more numerous low-mass cousins. Previous theoretical and observational studies have concluded that the feedback associated with massive stars' radiation fields is the dominant mechanism regulating massive star and massive star cluster (MSC) formation. Therefore detailed simulation of the formation of massive stars and MSCs, which host hundreds to thousands of massive stars, requires an accurate treatment of radiation. For this purpose, we have developed a new, highly accurate hybrid radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. We use our new tool to perform a suite of three-dimensional radiation-hydrodynamic simulations of the formation of massive stars and MSCs. For individual massive stellar systems, we simulate the collapse of massive pre-stellar cores with laminar and turbulent initial conditions and properly resolve regions where we expect instabilities to grow. We find that mass is channeled to the massive stellar system via gravitational and Rayleigh-Taylor (RT) instabilities. For laminar initial conditions, proper treatment of the direct radiation field produces later onset of RT instability, but does not suppress it entirely provided the edges of the radiation-dominated bubbles are adequately resolved. RT instabilities arise immediately for turbulent pre-stellar cores because the initial turbulence seeds the instabilities. To model MSC formation, we simulate the collapse of a dense, turbulent, magnetized Mcl = 106 M⊙ molecular cloud. We find that the influence of the magnetic pressure and radiative feedback slows down star formation. Furthermore, we find that star formation is suppressed along dense filaments where the magnetic field is

  11. Superradiance in the BTZ black hole with Robin boundary conditions

    Science.gov (United States)

    Dappiaggi, Claudio; Ferreira, Hugo R. C.; Herdeiro, Carlos A. R.

    2018-03-01

    We show the existence of superradiant modes of massive scalar fields propagating in BTZ black holes when certain Robin boundary conditions, which never include the commonly considered Dirichlet boundary conditions, are imposed at spatial infinity. These superradiant modes are defined as those solutions whose energy flux across the horizon is towards the exterior region. Differently from rotating, asymptotically flat black holes, we obtain that not all modes which grow up exponentially in time are superradiant; for some of these, the growth is sourced by a bulk instability of AdS3, triggered by the scalar field with Robin boundary conditions, rather than by energy extraction from the BTZ black hole. Thus, this setup provides an example wherein Bosonic modes with low frequency are pumping energy into, rather than extracting energy from, a rotating black hole.

  12. Sowing Black Hole Seeds: Forming Direct Collapse Black Holes With Realistic Lyman-Werner Radiation Fields in Cosmological Simulations

    Science.gov (United States)

    Holley-Bockelmann, Kelly; Dunn, Glenna; Bellovary, Jillian M.; Christensen, Charlotte

    2016-01-01

    Luminous quasars detected at redshifts z > 6 require that the first black holes form early and grow to ~109 solar masses within one Gyr. Our work uses cosmological simulations to study the formation and early growth of direct collapse black holes. In the pre-reionization epoch, molecular hydrogen (H2) causes gas to fragment and form Population III stars, but Lyman-Werner radiation can suppress H2 formation and allow gas to collapse directly into a massive black hole. The critical flux required to inhibit H2 formation, Jcrit, is hotly debated, largely due to the uncertainties in the source radiation spectrum, H2 self-shielding, and collisional dissociation rates. Here, we test the power of the direct collapse model in a non-uniform Lyman-Werner radiation field, using an updated version of the SPH+N-body tree code Gasoline with H2 non-equilibrium abundance tracking, H2 cooling, and a modern SPH implementation. We vary Jcrit from 30 to 104 J21 to study the effect on seed black holes, focusing on black hole formation as a function of environment, halo mass, metallicity, and proximity of the Lyman-Werner source. We discuss the constraints on massive black hole occupation fraction in the quasar epoch, and implications for reionization, high-redshift X-ray background radiation, and gravitational waves.

  13. Massive soliton stars

    Science.gov (United States)

    Chiu, Hong-Yee

    1990-01-01

    The structure of nontopological solutions of Einstein field equations as proposed by Friedberg, Lee, and Pang (1987) is examined. This analysis incorporates finite temperature effects and pair creation. Quarks are assumed to be the only species that exist in interior of soliton stars. The possibility of primordial creation of soliton stars in the incomplete decay of the degenerate vacuum in early universe is explored. Because of dominance of pair creation inside soliton stars, the luminosity of soliton stars is not determined by its radiative transfer characteristics, and the surface temperature of soliton stars can be the same as its interior temperature. It is possible that soliton stars are intense X-ray radiators at large distances. Soliton stars are nearly 100 percent efficient energy converters, converting the rest energy of baryons entering the interior into radiation. It is possible that a sizable number of baryons may also be trapped inside soliton stars during early epochs of the universe. In addition, if soliton stars exist they could assume the role played by massive black holes in galactic centers.

  14. Ileal amino acid digestibility in canola meals from yellow- and black-seeded Brassica napus and Brassica juncea fed to growing pigs.

    Science.gov (United States)

    Trindade Neto, M A; Opepaju, F O; Slominski, B A; Nyachoti, C M

    2012-10-01

    Twelve ileal cannulated pigs (30.9 ± 2.7 kg) were used to determine the apparent (AID) and standardized (SID) ileal digestibility of protein and AA in canola meals (CM) derived from black- (BNB) and yellow-seeded (BNY) Brassica napus canola and yellow-seeded Brassica juncea (BJY). The meals were produced using either the conventional pre-press solvent extraction process (regular meal) or a new, vacuum-assisted cold process of meal de-solventization (white flakes) to provide 6 different meals. Six cornstarch-based diets containing 35% canola meal as the sole source of protein in a 3 (variety) × 2 (processing) factorial arrangement were randomly allotted to pigs in a 6 × 7 incomplete Latin square design to have 6 replicates per diet. A 5% casein diet was fed to estimate endogenous AA losses. Canola variety and processing method interacted for the AID of DM (P = 0.048), N (P = 0.010), and all AA (P Canola variety affected or tended to affect the AID of most AA but had no effect on the AID of Lys, Met, Val, Cys, and Pro, whereas processing method had an effect on only Lys and Asp and tended to affect the AID of Thr, Gly and Ser. The effects of canola variety, processing method, and their interaction on the SID values for N and AA followed a similar pattern as for AID values. For the white flakes, SID of N in BJY (74.2%) was lower than in BNY and BNB, whose values averaged 78.5%; however, among the regular meals, BJY had a greater SID value for N than BNY and BNB (variety × processing, P = 0.015). For the white flakes, the SID of Ile (86.4%), Leu (87.6%), Lys (88.9%), Thr (87.6%) and Val (84.2%) in BNB were greater than BNY and BJY. Opposite results were observed for the regular processing, with SID of Lys (84.1%), Met (89.5%), Thr (84.1%), and Val (83.6%) being greater in BJY, followed by BNB and BNY(variety × processing, P canola variety and the processing method used. Overall, the SID values for Ile, Leu, Lys, Met, Thr, and Val averaged across CM types and

  15. New massive gravity

    NARCIS (Netherlands)

    Bergshoeff, Eric A.; Hohm, Olaf; Townsend, Paul K.

    2012-01-01

    We present a brief review of New Massive Gravity, which is a unitary theory of massive gravitons in three dimensions obtained by considering a particular combination of the Einstein-Hilbert and curvature squared terms.

  16. Black holes

    International Nuclear Information System (INIS)

    Carter, B.

    1980-01-01

    In years 1920 as a result of quantum mechanics principles governing the structure of ordinary matter, a sudden importance for a problem raised a long time ago by Laplace: what happens when a massive body becomes so dense that even light cannot escape from its gravitational field. It is difficult to conceive how could be avoided in the actual universe the accumulation of important masses of cold matter having been submitted to gravitational breaking down followed by the formation of what is called to day a black hole [fr

  17. Epidemiology of Massive Transfusion

    DEFF Research Database (Denmark)

    Halmin, Märit; Chiesa, Flaminia; Vasan, Senthil K

    2016-01-01

    OBJECTIVE: There is an increasing focus on massive transfusion, but there is a paucity of comprehensive descriptions of the massively transfused patients and their outcomes. The objective of this study is to describe the incidence rate of massive transfusion, patient characteristics, and the mort...

  18. ULTRAMASSIVE BLACK HOLE COALESCENCE

    International Nuclear Information System (INIS)

    Khan, Fazeel Mahmood; Holley-Bockelmann, Kelly; Berczik, Peter

    2015-01-01

    Although supermassive black holes (SMBHs) correlate well with their host galaxies, there is an emerging view that outliers exist. Henize 2-10, NGC 4889, and NGC 1277 are examples of SMBHs at least an order of magnitude more massive than their host galaxy suggests. The dynamical effects of such ultramassive central black holes is unclear. Here, we perform direct N-body simulations of mergers of galactic nuclei where one black hole is ultramassive to study the evolution of the remnant and the black hole dynamics in this extreme regime. We find that the merger remnant is axisymmetric near the center, while near the large SMBH influence radius, the galaxy is triaxial. The SMBH separation shrinks rapidly due to dynamical friction, and quickly forms a binary black hole; if we scale our model to the most massive estimate for the NGC 1277 black hole, for example, the timescale for the SMBH separation to shrink from nearly a kiloparsec to less than a parsec is roughly 10 Myr. By the time the SMBHs form a hard binary, gravitational wave emission dominates, and the black holes coalesce in a mere few Myr. Curiously, these extremely massive binaries appear to nearly bypass the three-body scattering evolutionary phase. Our study suggests that in this extreme case, SMBH coalescence is governed by dynamical friction followed nearly directly by gravitational wave emission, resulting in a rapid and efficient SMBH coalescence timescale. We discuss the implications for gravitational wave event rates and hypervelocity star production

  19. Core Formation by a Population of Massive Remnants

    NARCIS (Netherlands)

    Merritt, D.; Piatek, S.; Portegies Zwart, S.F.; Hemsendorf, M.

    2004-01-01

    Core radii of globular clusters in the Large and Small Magellanic Clouds show an increasing trend with age. We propose that this trend is a dynamical effect resulting from the accumulation of massive stars and stellar-mass black holes at the cluster centers. The black holes are remnants of stars

  20. Black holes with halos

    Science.gov (United States)

    Monten, Ruben; Toldo, Chiara

    2018-02-01

    We present new AdS4 black hole solutions in N =2 gauged supergravity coupled to vector and hypermultiplets. We focus on a particular consistent truncation of M-theory on the homogeneous Sasaki–Einstein seven-manifold M 111, characterized by the presence of one Betti vector multiplet. We numerically construct static and spherically symmetric black holes with electric and magnetic charges, corresponding to M2 and M5 branes wrapping non-contractible cycles of the internal manifold. The novel feature characterizing these nonzero temperature configurations is the presence of a massive vector field halo. Moreover, we verify the first law of black hole mechanics and we study the thermodynamics in the canonical ensemble. We analyze the behavior of the massive vector field condensate across the small-large black hole phase transition and we interpret the process in the dual field theory.

  1. Chandra Catches "Piranha" Black Holes

    Science.gov (United States)

    2007-07-01

    Supermassive black holes have been discovered to grow more rapidly in young galaxy clusters, according to new results from NASA's Chandra X-ray Observatory. These "fast-track" supermassive black holes can have a big influence on the galaxies and clusters that they live in. Using Chandra, scientists surveyed a sample of clusters and counted the fraction of galaxies with rapidly growing supermassive black holes, known as active galactic nuclei (or AGN). The data show, for the first time, that younger, more distant galaxy clusters contained far more AGN than older, nearby ones. Galaxy clusters are some of the largest structures in the Universe, consisting of many individual galaxies, a few of which contain AGN. Earlier in the history of the universe, these galaxies contained a lot more gas for star formation and black hole growth than galaxies in clusters do today. This fuel allows the young cluster black holes to grow much more rapidly than their counterparts in nearby clusters. Illustration of Active Galactic Nucleus Illustration of Active Galactic Nucleus "The black holes in these early clusters are like piranha in a very well-fed aquarium," said Jason Eastman of Ohio State University (OSU) and first author of this study. "It's not that they beat out each other for food, rather there was so much that all of the piranha were able to really thrive and grow quickly." The team used Chandra to determine the fraction of AGN in four different galaxy clusters at large distances, when the Universe was about 58% of its current age. Then they compared this value to the fraction found in more nearby clusters, those about 82% of the Universe's current age. The result was the more distant clusters contained about 20 times more AGN than the less distant sample. AGN outside clusters are also more common when the Universe is younger, but only by factors of two or three over the same age span. "It's been predicted that there would be fast-track black holes in clusters, but we never

  2. Cosmological perturbations in massive bigravity

    International Nuclear Information System (INIS)

    Lagos, Macarena; Ferreira, Pedro G.

    2014-01-01

    We present a comprehensive analysis of classical scalar, vector and tensor cosmological perturbations in ghost-free massive bigravity. In particular, we find the full evolution equations and analytical solutions in a wide range of regimes. We show that there are viable cosmological backgrounds but, as has been found in the literature, these models generally have exponential instabilities in linear perturbation theory. However, it is possible to find stable scalar cosmological perturbations for a very particular choice of parameters. For this stable subclass of models we find that vector and tensor perturbations have growing solutions. We argue that special initial conditions are needed for tensor modes in order to have a viable model

  3. Black Holes in Our Universe

    Indian Academy of Sciences (India)

    was discovered in the constellation Cygnus; a bright X-ray emit- ter associated with a twin-star system, and christened Cygnus X-. 1. It has a massive star and a black hole orbiting each other. With an optical telescope it is the companion star of the black hole which is visible, which produces stellar winds blowing away from.

  4. Growing a market economy

    Energy Technology Data Exchange (ETDEWEB)

    Basu, N.; Pryor, R.J.

    1997-09-01

    This report presents a microsimulation model of a transition economy. Transition is defined as the process of moving from a state-enterprise economy to a market economy. The emphasis is on growing a market economy starting from basic microprinciples. The model described in this report extends and modifies the capabilities of Aspen, a new agent-based model that is being developed at Sandia National Laboratories on a massively parallel Paragon computer. Aspen is significantly different from traditional models of the economy. Aspen`s emphasis on disequilibrium growth paths, its analysis based on evolution and emergent behavior rather than on a mechanistic view of society, and its use of learning algorithms to simulate the behavior of some agents rather than an assumption of perfect rationality make this model well-suited for analyzing economic variables of interest from transition economies. Preliminary results from several runs of the model are included.

  5. Statistical mechanics of black holes

    International Nuclear Information System (INIS)

    Harms, B.; Leblanc, Y.

    1992-01-01

    We analyze the statistical mechanics of a gas of neutral and charged black holes. The microcanonical ensemble is the only possible approach to this system, and the equilibrium configuration is the one for which most of the energy is carried by a single black hole. Schwarzschild black holes are found to obey the statistical bootstrap condition. In all cases, the microcanonical temperature is identical to the Hawking temperature of the most massive black hole in the gas. U(1) charges in general break the bootstrap property. The problems of black-hole decay and of quantum coherence are also addressed

  6. Massive public investment needed to grow green economy.

    Science.gov (United States)

    2009-01-01

    The President of the Communications Workers of America, Larry Cohen, urges large-scale investments in research and technology in response to economic turmoil and climate change. He envisions one million made-in-America hybrid cars running on U.S. roadways by 2015 and use of alternative energy doubling within three years.

  7. Feedback Limits to Maximum Seed Masses of Black Holes

    International Nuclear Information System (INIS)

    Pacucci, Fabio; Natarajan, Priyamvada; Ferrara, Andrea

    2017-01-01

    The most massive black holes observed in the universe weigh up to ∼10 10 M ⊙ , nearly independent of redshift. Reaching these final masses likely required copious accretion and several major mergers. Employing a dynamical approach that rests on the role played by a new, relevant physical scale—the transition radius—we provide a theoretical calculation of the maximum mass achievable by a black hole seed that forms in an isolated halo, one that scarcely merged. Incorporating effects at the transition radius and their impact on the evolution of accretion in isolated halos, we are able to obtain new limits for permitted growth. We find that large black hole seeds ( M • ≳ 10 4 M ⊙ ) hosted in small isolated halos ( M h ≲ 10 9 M ⊙ ) accreting with relatively small radiative efficiencies ( ϵ ≲ 0.1) grow optimally in these circumstances. Moreover, we show that the standard M • – σ relation observed at z ∼ 0 cannot be established in isolated halos at high- z , but requires the occurrence of mergers. Since the average limiting mass of black holes formed at z ≳ 10 is in the range 10 4–6 M ⊙ , we expect to observe them in local galaxies as intermediate-mass black holes, when hosted in the rare halos that experienced only minor or no merging events. Such ancient black holes, formed in isolation with subsequent scant growth, could survive, almost unchanged, until present.

  8. Growing Pains

    CERN Multimedia

    Katarina Anthony

    2013-01-01

    Heat expands and cold contracts: it’s a simple thermodynamic rule. But when temperatures swing from 300 K to near-absolute zero, this rule can mean a contraction of more than 80 metres across the LHC’s 27-km-long cryogenic system. Keeping this growth in check are compensators (a.k.a. bellows), which shrink and stretch in response to thermodynamic changes. Leak tests and X-rays now underway in the tunnel have revealed that these “joints” might be suffering from growing pains…   This 25-μm weld crack is thought to be the cause of the helium leaks. Prior to the LS1 warm-up, CERN’s cryogenic experts knew of two points in the machine’s cryogenic distribution system that were leaking helium. Fortunately, these leaks were sufficiently small, confined to known sub-sectors of the cryogenic line and – with help from the vacuum team (TE-VSC) – could easily be compensated for. But as the machine warmed up f...

  9. Massive fetomaternal hemorrhage

    DEFF Research Database (Denmark)

    Larsen, Rune; Berkowicz, Adela; Lousen, Thea

    2008-01-01

    the maternal circulation by anti-D in clinical cases of massive fetomaternal hemorrhage (FMH). CASE REPORT: A 33-year-old D- woman delivered a D+ female infant by emergency cesarean section for suspected fetal anemia. A massive FMH, initially estimated to be approximately 142 mL of RBCs, was found. In addition...

  10. Simplifying Massive Contour Maps

    DEFF Research Database (Denmark)

    Arge, Lars; Deleuran, Lasse Kosetski; Mølhave, Thomas

    2012-01-01

    We present a simple, efficient and practical algorithm for constructing and subsequently simplifying contour maps from massive high-resolution DEMs, under some practically realistic assumptions on the DEM and contours.......We present a simple, efficient and practical algorithm for constructing and subsequently simplifying contour maps from massive high-resolution DEMs, under some practically realistic assumptions on the DEM and contours....

  11. Deformation of the Galactic Centre stellar cusp due to the gravity of a growing gas disc

    Science.gov (United States)

    Kaur, Karamveer; Sridhar, S.

    2018-03-01

    The nuclear star cluster surrounding the massive black hole at the Galactic Centre consists of young and old stars, with most of the stellar mass in an extended, cuspy distribution of old stars. The compact cluster of young stars was probably born in situ in a massive accretion disc around the black hole. We investigate the effect of the growing gravity of the disc on the orbits of the old stars, using an integrable model of the deformation of a spherical star cluster with anisotropic velocity dispersions. A formula for the perturbed phase space distribution function is derived using linear theory, and new density and surface density profiles are computed. The cusp undergoes a spheroidal deformation with the flattening increasing strongly at smaller distances from the black hole; the intrinsic axis ratio ˜0.8 at ˜0.15 pc. Stellar orbits are deformed such that they spend more time near the disc plane and sample the dense inner parts of the disc; this could result in enhanced stripping of the envelopes of red giant stars. Linear theory accounts only for orbits whose apsides circulate. The non-linear theory of adiabatic capture into resonance is needed to understand orbits whose apsides librate. The mechanism is a generic dynamical process, and it may be common in galactic nuclei.

  12. GOODS Missing Black Hole Report: Hundreds Found!

    Science.gov (United States)

    2007-10-01

    Astronomers have unmasked hundreds of black holes hiding deep inside dusty galaxies billions of light-years away Normal Galaxies Normal Galaxies The massive, growing black holes, discovered by NASA's Spitzer and Chandra space telescopes, represent a large fraction of a long-sought missing population. Their discovery implies there are hundreds of millions of additional black holes growing in our young universe, more than doubling the total amount known at that distance. "Active, supermassive black holes are everywhere in the early universe," said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. "We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself." Dickinson is a co-author of two new papers appearing in the Nov. 10 issue of the Astrophysical Journal. Emanuele Daddi of the Commissariat a l'Energie Atomique in France led the research. The findings are also the first direct evidence that most, if not all, massive galaxies in the distant universe spend their youths building monstrous black holes at their cores. For decades, large populations of active black holes have been considered missing. These highly energetic structures, also called quasars, consist of a dusty, doughnut-shaped cloud that surrounds and feeds a growing supermassive black hole. They give off a lot of X-rays that can be detected as a general glow in space, but sometimes the quasars themselves can't be seen because dust and gas blocks their X-rays from our point of view. "We knew from other studies from about 30 years ago that there must be more quasars in the universe, but we didn't know where to find them until now," said Daddi. Daddi and his team initially set out to study 1,000 dusty, massive galaxies that are busy making stars, and were thought to lack quasars. The galaxies are about the same mass as our own spiral Milky Way galaxy, but irregular in shape. At 9 to 11 billion light-years away, they exist at a

  13. Uncovering Black Womanhood in Engineering

    Science.gov (United States)

    Gibson, Sheree L.; Espino, Michelle M.

    2016-01-01

    Despite the growing research that outlines the experiences of Blacks and women undergraduates in engineering, little is known about Black women in this field. The purpose of this qualitative study was to uncover how eight Black undergraduate women in engineering understood their race and gender identities in a culture that can be oppressive to…

  14. EXPLORING THE UNUSUALLY HIGH BLACK-HOLE-TO-BULGE MASS RATIOS IN NGC 4342 AND NGC 4291: THE ASYNCHRONOUS GROWTH OF BULGES AND BLACK HOLES

    International Nuclear Information System (INIS)

    Bogdán, Ákos; Forman, William R.; Kraft, Ralph P.; Li, Zhiyuan; Vikhlinin, Alexey; Nulsen, Paul E. J.; Jones, Christine; Zhuravleva, Irina; Churazov, Eugene; Mihos, J. Christopher; Harding, Paul; Guo, Qi; Schindler, Sabine

    2012-01-01

    We study two nearby early-type galaxies, NGC 4342 and NGC 4291, that host unusually massive black holes relative to their low stellar mass. The observed black-hole-to-bulge mass ratios of NGC 4342 and NGC 4291 are 6.9 +3.8 –2.3 % and 1.9% ± 0.6%, respectively, which significantly exceed the typical observed ratio of ∼0.2%. As a consequence of the exceedingly large black-hole-to-bulge mass ratios, NGC 4342 and NGC 4291 are ≈5.1σ and ≈3.4σ outliers from the M . -M bulge scaling relation, respectively. In this paper, we explore the origin of the unusually high black-hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC 4342 and NGC 4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC 4342 and NGC 4291 and a deep optical image of the environment of NGC 4342 indicate that tidal stripping, in which ∼> 90% of the stellar mass was lost, cannot explain the observed high black-hole-to-bulge mass ratios. Therefore, we conclude that these galaxies formed with low stellar masses, implying that the bulge and black hole did not grow in tandem. We also find that the black hole mass correlates well with the properties of the dark matter halo, suggesting that dark matter halos may play a major role in regulating the growth of the supermassive black holes.

  15. Quantum massive conformal gravity

    Energy Technology Data Exchange (ETDEWEB)

    Faria, F.F. [Universidade Estadual do Piaui, Centro de Ciencias da Natureza, Teresina, PI (Brazil)

    2016-04-15

    We first find the linear approximation of the second plus fourth order derivative massive conformal gravity action. Then we reduce the linearized action to separated second order derivative terms, which allows us to quantize the theory by using the standard first order canonical quantization method. It is shown that quantum massive conformal gravity is renormalizable but has ghost states. A possible decoupling of these ghost states at high energies is discussed. (orig.)

  16. Massive neutrinos in astrophysics

    International Nuclear Information System (INIS)

    Qadir, A.

    1982-08-01

    Massive neutrinos are among the big hopes of cosmologists. If they happen to have the right mass they can close the Universe, explain the motion of galaxies in clusters, provide galactic halos and even, possibly, explain galaxy formation. Tremaine and Gunn have argued that massive neutrinos cannot do all these things. I will explain, here, what some of us believe is wrong with their arguments. (author)

  17. An intermediate-mass black hole in the centre of the globular cluster 47 Tucanae.

    Science.gov (United States)

    Kızıltan, Bülent; Baumgardt, Holger; Loeb, Abraham

    2017-02-08

    Intermediate-mass black holes should help us to understand the evolutionary connection between stellar-mass and super-massive black holes. However, the existence of intermediate-mass black holes is still uncertain, and their formation process is therefore unknown. It has long been suspected that black holes with masses 100 to 10,000 times that of the Sun should form and reside in dense stellar systems. Therefore, dedicated observational campaigns have targeted globular clusters for many decades, searching for signatures of these elusive objects. All candidate signatures appear radio-dim and do not have the X-ray to radio flux ratios required for accreting black holes. Based on the lack of an electromagnetic counterpart, upper limits of 2,060 and 470 solar masses have been placed on the mass of a putative black hole in 47 Tucanae (NGC 104) from radio and X-ray observations, respectively. Here we show there is evidence for a central black hole in 47 Tucanae with a mass of solar masses when the dynamical state of the globular cluster is probed with pulsars. The existence of an intermediate-mass black hole in the centre of one of the densest clusters with no detectable electromagnetic counterpart suggests that the black hole is not accreting at a sufficient rate to make it electromagnetically bright and therefore, contrary to expectations, is gas-starved. This intermediate-mass black hole might be a member of an electromagnetically invisible population of black holes that grow into supermassive black holes in galaxies.

  18. Massive graviton geons

    Science.gov (United States)

    Aoki, Katsuki; Maeda, Kei-ichi; Misonoh, Yosuke; Okawa, Hirotada

    2018-02-01

    We find vacuum solutions such that massive gravitons are confined in a local spacetime region by their gravitational energy in asymptotically flat spacetimes in the context of the bigravity theory. We call such self-gravitating objects massive graviton geons. The basic equations can be reduced to the Schrödinger-Poisson equations with the tensor "wave function" in the Newtonian limit. We obtain a nonspherically symmetric solution with j =2 , ℓ=0 as well as a spherically symmetric solution with j =0 , ℓ=2 in this system where j is the total angular momentum quantum number and ℓ is the orbital angular momentum quantum number, respectively. The energy eigenvalue of the Schrödinger equation in the nonspherical solution is smaller than that in the spherical solution. We then study the perturbative stability of the spherical solution and find that there is an unstable mode in the quadrupole mode perturbations which may be interpreted as the transition mode to the nonspherical solution. The results suggest that the nonspherically symmetric solution is the ground state of the massive graviton geon. The massive graviton geons may decay in time due to emissions of gravitational waves but this timescale can be quite long when the massive gravitons are nonrelativistic and then the geons can be long-lived. We also argue possible prospects of the massive graviton geons: applications to the ultralight dark matter scenario, nonlinear (in)stability of the Minkowski spacetime, and a quantum transition of the spacetime.

  19. Black to Black

    DEFF Research Database (Denmark)

    Langkjær, Michael Alexander

    2012-01-01

    Pop musicians performing in black stage costume take advantage of cultural traditions relating to matters black. Stylistically, black is a paradoxical color: although a symbol of melancholy, pessimism, and renunciation, black also expresses minimalist modernity and signifies exclusivity (as is hi...... suggested that appreciation of the highly personal motives of both Siouxsie Sioux and Janelle Monáe in wearing black may be achieved via analogies with the minimalist sublime of American artists Frank Stella’s and Ad Reinhardt’s black canvasses.......Pop musicians performing in black stage costume take advantage of cultural traditions relating to matters black. Stylistically, black is a paradoxical color: although a symbol of melancholy, pessimism, and renunciation, black also expresses minimalist modernity and signifies exclusivity (as...... is hinted by Rudyard Kipling’s illustration of ‘The [Black] Cat That Walked by Himself’ in his classic children’s tale). It was well understood by uniformed Anarchists, Fascists and the SS that there is an assertive presence connected with the black-clad figure. The paradox of black’s abstract elegance...

  20. No hair theorem in quasi-dilaton massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, De-Jun, E-mail: wudejun10@mails.ucas.ac.cn [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Shuang-Yong, E-mail: sxz353@case.edu [Department of Physics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106 (United States)

    2016-06-10

    We investigate the static, spherically symmetric black hole solutions in the quasi-dilaton model and its generalizations, which are scalar extended dRGT massive gravity with a shift symmetry. We show that, unlike generic scalar extended massive gravity models, these theories do not admit static, spherically symmetric black hole solutions until the theory parameters in the dRGT potential are fine-tuned. When fine-tuned, the geometry of the static, spherically symmetric black hole is necessarily that of general relativity and the quasi-dilaton field is constant across the spacetime. The fine-tuning and the no hair theorem apply to black holes with flat, anti-de Sitter or de Sitter asymptotics.

  1. Cosmic decoherence: massive fields

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Junyu [Department of Physics, California Institute of Technology,Pasadena, California 91125 (United States); School of the Gifted Young, University of Science and Technology of China,Hefei, Anhui 230026 (China); Sou, Chon-Man; Wang, Yi [Department of Physics, The Hong Kong University of Science and Technology,Clear Water Bay, Kowloon, Hong Kong (China)

    2016-10-14

    We study the decoherence of massive fields during inflation based on the Zurek’s density matrix approach. With the cubic interaction between inflaton and massive fields, the reduced density matrix for the massive fields can be calculated in the Schrödinger picture which is related to the variance of the non-Gaussian exponent in the wave functional. The decoherence rate is computed in the one-loop form from functional integration. For heavy fields with m≳O(H), quantum fluctuations will easily stay in the quantum state and decoherence is unlikely. While for light fields with mass smaller than O(H), quantum fluctuations are easily decohered within 5∼10 e-folds after Hubble crossing. Thus heavy fields can play a key role in studying problems involving inflationary quantum information.

  2. Massive Multiplayer Online Games im mobilen Kontext

    OpenAIRE

    Fritsch, Tobias

    2010-01-01

    Within the last few years, the importance of (multiplayer) computer games has experienced immense growth. On par with that, the size of persistent virtual environments (VEs) has also increased. Today, more than 120 MMOGs (Massive Multiplayer Online Games) ranging from FPS (first person shooter) to classic RPG (role playing game) settings exist. This illustrates the significant influence of the growing number of simultaneously playing users. The way that games are played has also evolved. N...

  3. Bumpy black holes from spontaneous Lorentz violation

    International Nuclear Information System (INIS)

    Dubovsky, Sergei; Tinyakov, Peter; Zaldarriaga, Matias

    2007-01-01

    We consider black holes in Lorentz violating theories of massive gravity. We argue that in these theories black hole solutions are no longer universal and exhibit a large number of hairs. If they exist, these hairs probe the singularity inside the black hole providing a window into quantum gravity. The existence of these hairs can be tested by future gravitational wave observatories. We generically expect that the effects we discuss will be larger for the more massive black holes. In the simplest models the strength of the hairs is controlled by the same parameter that sets the mass of the graviton (tensor modes). Then the upper limit on this mass coming from the inferred gravitational radiation emitted by binary pulsars implies that hairs are likely to be suppressed for almost the entire mass range of the super-massive black holes in the centers of galaxies

  4. Black hole growth in the early Universe is self-regulated and largely hidden from view.

    Science.gov (United States)

    Treister, Ezequiel; Schawinski, Kevin; Volonteri, Marta; Natarajan, Priyamvada; Gawiser, Eric

    2011-06-15

    The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. Although some black holes with masses more than 10(9) times that of the Sun have been detected in luminous quasars less than one billion years after the Big Bang, these individual extreme objects have limited utility in constraining the channels of formation of the earliest black holes; this is because the initial conditions of black hole seed properties are quickly erased during the growth process. Here we report a measurement of the amount of black hole growth in galaxies at redshift z = 6-8 (0.95-0.7 billion years after the Big Bang), based on optimally stacked, archival X-ray observations. Our results imply that black holes grow in tandem with their host galaxies throughout cosmic history, starting from the earliest times. We find that most copiously accreting black holes at these epochs are buried in significant amounts of gas and dust that absorb most radiation except for the highest-energy X-rays. This suggests that black holes grew significantly more during these early bursts than was previously thought, but because of the obscuration of their ultraviolet emission they did not contribute to the re-ionization of the Universe.

  5. Testing the blazar sequence and black hole mass scaling with BL Lac objects

    NARCIS (Netherlands)

    Plotkin, Richard M.; Markoff, Sera; Anderson, Scott F.; Kelly, Brandon C.; Körding, Elmar; Trager, Scott C.; Romero, Gustavo E.; Sunyaev, Rashid A.; Belloni, Tomaso

    Jets from accreting black holes appear remarkably similar over eight orders of magnitude in black hole mass, with more massive black holes generally launching more powerful jets. For example, there is an observed correlation, termed the fundamental plane of black hole accretion, between black hole

  6. Testing the blazar sequence and black hole mass scaling with BL Lac objects

    NARCIS (Netherlands)

    Plotkin, R.M.; Markoff, S.; Anderson, S.F.; Kelly, B.C.; Körding, E.; Trager, S.C.

    2010-01-01

    Jets from accreting black holes appear remarkably similar over eight orders of magnitude in black hole mass, with more massive black holes generally launching more powerful jets. For example, there is an observed correlation, termed the fundamental plane of black hole accretion, between black hole

  7. Epidemiology of massive transfusion

    DEFF Research Database (Denmark)

    Halmin, M. A. H.; Chiesa, F. C.; Vasan, S. K. V.

    2015-01-01

    and to describe characteristics and mortality of massively transfused patients. Methods: We performed a retrospective cohort study based on the Scandinavian Donations and Transfusions (SCANDAT2) database, linking data on blood donation, blood components and transfused patients with inpatient- and population....... Post-transfusion mortality was expressed as crude 30-days mortality and long-term mortality was estimated using the Kaplan-Meier method and as standardized mortality ratios. Results: 53,836 patients were included. Of all blood components transfused during the study period, 7.7% constituted massive...

  8. Topologically massive supergravity

    Directory of Open Access Journals (Sweden)

    S. Deser

    1983-01-01

    Full Text Available The locally supersymmetric extension of three-dimensional topologically massive gravity is constructed. Its fermionic part is the sum of the (dynamically trivial Rarita-Schwinger action and a gauge-invariant topological term, of second derivative order, analogous to the gravitational one. It is ghost free and represents a single massive spin 3/2 excitation. The fermion-gravity coupling is minimal and the invariance is under the usual supergravity transformations. The system's energy, as well as that of the original topological gravity, is therefore positive.

  9. Partons and black holes

    International Nuclear Information System (INIS)

    Susskind, L.; Griffin, P.

    1994-01-01

    A light-front renormalization group analysis is applied to study matter which falls into massive black holes, and the related problem of matter with transplankian energies. One finds that the rate of matter spreading over the black hole's horizon unexpectedly saturates the causality bound. This is related to the transverse growth behavior of transplankian particles as their longitudinal momentum increases. This growth behavior suggests a natural mechanism to implement 't Hooft's scenario that the universe is an image of data stored on a 2 + 1 dimensional hologram-like projection

  10. How Massive Single Stars End Their Life

    Science.gov (United States)

    Heger, A.; Fryer, C. L.; Woosley, S. E.; Langer, N.; Hartmann, D. H.

    2003-01-01

    How massive stars die-what sort of explosion and remnant each produces-depends chiefly on the masses of their helium cores and hydrogen envelopes at death. For single stars, stellar winds are the only means of mass loss, and these are a function of the metallicity of the star. We discuss how metallicity, and a simplified prescription for its effect on mass loss, affects the evolution and final fate of massive stars. We map, as a function of mass and metallicity, where black holes and neutron stars are likely to form and where different types of supernovae are produced. Integrating over an initial mass function, we derive the relative populations as a function of metallicity. Provided that single stars rotate rapidly enough at death, we speculate on stellar populations that might produce gamma-ray bursts and jet-driven supernovae.

  11. Sinus Histiocytosis with Massive Lymphadenopathy | Sinclair-Smith ...

    African Journals Online (AJOL)

    Two cases of a recently described entity, 'sinus histiocytosis with massive lymphadenopathy,' occurring in Black males, are reported. Prominent cervical adenopathy was the main presenting feature in both. Histologically, these nodes were characterised by pronounced proliferation of sinus histiocytes which showed ...

  12. Massive Stars as Progenitors of Supernovae and GRBs

    NARCIS (Netherlands)

    Langer, N.; van Marle, A.J.; Poelarends, A.J.T.; Yoon, S.C.

    2007-01-01

    The evolutionary fate of massive stars in our Milky Way is thought to be reasonably well understood: stars above ˜ 8 M_o produce neutron stars and supernovae, while those above ˜ 20...30 M_o are presumed to form black holes. At metallicities below that of the SMC, however, our knowledge becomes

  13. Correlations Between Central Massive Objects And Their Host Galaxies: From Bulgeless Spirals to Ellipticals

    OpenAIRE

    Li, Yuexing; Haiman, Zoltán; Mac Low, Mordecai-Mark

    2006-01-01

    Recent observations by Ferrarese et al. (2006) and Wehner et al. (2006) reveal that a majority of galaxies contain a central massive object (CMO), either a supermassive black hole (SMBH) or a compact stellar nucleus, regardless of the galaxy mass or morphological type, and that there is a tight relation between the masses of CMOs and those of the host galaxies. Several recent studies show that feedback from black holes can successfully explain the $\\msigma$ correlation in massive elliptical g...

  14. Radiology in massive hemoptysis

    International Nuclear Information System (INIS)

    Marini, M.; Castro, J.M.; Gayol, A.; Aguilera, C.; Blanco, M.; Beraza, A.; Torres, J.

    1995-01-01

    We have reviewed our experience in diseases involving massive hemoptysis, systematizing the most common causes which include tuberculosis, bronchiectasis and cancer of the lung. Other less frequent causes, such as arteriovenous fistula, Aspergilloma, aneurysm, etc.; are also evaluated, and the most demonstrative images of each produced by the most precise imaging methods for their assessment are presented

  15. Massive Supergravity and Deconstruction

    CERN Document Server

    Gregoire, T; Shadmi, Y; Gregoire, Thomas; Schwartz, Matthew D; Shadmi, Yael

    2004-01-01

    We present a simple superfield Lagrangian for massive supergravity. It comprises the minimal supergravity Lagrangian with interactions as well as mass terms for the metric superfield and the chiral compensator. This is the natural generalization of the Fierz-Pauli Lagrangian for massive gravity which comprises mass terms for the metric and its trace. We show that the on-shell bosonic and fermionic fields are degenerate and have the appropriate spins: 2, 3/2, 3/2 and 1. We then study this interacting Lagrangian using goldstone superfields. We find that a chiral multiplet of goldstones gets a kinetic term through mixing, just as the scalar goldstone does in the non-supersymmetric case. This produces Planck scale (Mpl) interactions with matter and all the discontinuities and unitarity bounds associated with massive gravity. In particular, the scale of strong coupling is (Mpl m^4)^1/5, where m is the multiplet's mass. Next, we consider applications of massive supergravity to deconstruction. We estimate various qu...

  16. Massively parallel signature sequencing.

    Science.gov (United States)

    Zhou, Daixing; Rao, Mahendra S; Walker, Roger; Khrebtukova, Irina; Haudenschild, Christian D; Miura, Takumi; Decola, Shannon; Vermaas, Eric; Moon, Keith; Vasicek, Thomas J

    2006-01-01

    Massively parallel signature sequencing is an ultra-high throughput sequencing technology. It can simultaneously sequence millions of sequence tags, and, therefore, is ideal for whole genome analysis. When applied to expression profiling, it reveals almost every transcript in the sample and provides its accurate expression level. This chapter describes the technology and its application in establishing stem cell transcriptome databases.

  17. Massive antenatal fetomaternal hemorrhage

    DEFF Research Database (Denmark)

    Dziegiel, Morten Hanefeld; Koldkjaer, Ole; Berkowicz, Adela

    2005-01-01

    Massive fetomaternal hemorrhage (FMH) can lead to life-threatening anemia. Quantification based on flow cytometry with anti-hemoglobin F (HbF) is applicable in all cases but underestimation of large fetal bleeds has been reported. A large FMH from an ABO-compatible fetus allows an estimation...

  18. COLA with massive neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Bill S.; Winther, Hans A.; Koyama, Kazuya, E-mail: bill.wright@port.ac.uk, E-mail: hans.winther@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, Hampshire, PO1 3FX (United Kingdom)

    2017-10-01

    The effect of massive neutrinos on the growth of cold dark matter perturbations acts as a scale-dependent Newton's constant and leads to scale-dependent growth factors just as we often find in models of gravity beyond General Relativity. We show how to compute growth factors for ΛCDM and general modified gravity cosmologies combined with massive neutrinos in Lagrangian perturbation theory for use in COLA and extensions thereof. We implement this together with the grid-based massive neutrino method of Brandbyge and Hannestad in MG-PICOLA and compare COLA simulations to full N -body simulations of ΛCDM and f ( R ) gravity with massive neutrinos. Our implementation is computationally cheap if the underlying cosmology already has scale-dependent growth factors and it is shown to be able to produce results that match N -body to percent level accuracy for both the total and CDM matter power-spectra up to k ∼< 1 h /Mpc.

  19. Supertwistors and massive particles

    Energy Technology Data Exchange (ETDEWEB)

    Mezincescu, Luca, E-mail: mezincescu@server.physics.miami.edu [Department of Physics, University of Miami, Coral Gables, FL 33124 (United States); Routh, Alasdair J., E-mail: a.j.routh@damtp.cam.ac.uk [DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Townsend, Paul K., E-mail: p.k.townsend@damtp.cam.ac.uk [DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2014-07-15

    In the (super)twistor formulation of massless (super)particle mechanics, the mass-shell constraint is replaced by a “spin-shell” constraint from which the spin content can be read off. We extend this formalism to massive (super)particles (with N-extended space–time supersymmetry) in three and four space–time dimensions, explaining how the spin-shell constraints are related to spin, and we use it to prove equivalence of the massive N=1 and BPS-saturated N=2 superparticle actions. We also find the supertwistor form of the action for “spinning particles” with N-extended worldline supersymmetry, massless in four dimensions and massive in three dimensions, and we show how this simplifies special features of the N=2 case. -- Highlights: •Spin-shell constraints are related to Poincaré Casimirs. •Twistor form of 4D spinning particle for spin N/2. •Twistor proof of scalar/antisymmetric tensor equivalence for 4D spin 0. •Twistor form of 3D particle with arbitrary spin. •Proof of equivalence of N=1 and N=2 BPS massive 4D superparticles.

  20. Unveiling the First Black Holes With JWST:Multi-wavelength Spectral Predictions

    Science.gov (United States)

    Natarajan, Priyamvada; Pacucci, Fabio; Ferrara, Andrea; Agarwal, Bhaskar; Ricarte, Angelo; Zackrisson, Erik; Cappelluti, Nico

    2017-04-01

    Growing supermassive black holes (˜ {10}9 {M}⊙ ) that power luminous z> 6 quasars from light seeds—the remnants of the first stars—within a Gyr of the Big Bang poses a timing challenge. The formation of massive black hole seeds via direct collapse with initial masses ˜ {10}4{--}{10}5 {M}⊙ alleviates this problem. Viable direct-collapse black hole formation sites, the satellite halos of star-forming galaxies, merge and acquire stars to produce a new, transient class of high-redshift objects, obese black hole galaxies (OBGs). The accretion luminosity outshines that of the stars in OBGs. We predict the multi-wavelength energy output of OBGs and growing Pop III remnants at z = 9 for standard and slim disk accretion, as well as high and low metallicities of the associated stellar population. We derive robust selection criteria for OBGs—a pre-selection to eliminate blue sources, followed by color-color cuts ([{F}090W-{F}220W]> 0;-0.3sift out OBGs from other bright, high- and low-redshift contaminants in the infrared. OBGs with predicted {M}{AB}< 25 are unambiguously detectable by the Mid-Infrared Instrument (MIRI), on the upcoming James Webb Space Telescope (JWST). For parameters explored here, growing Pop III remnants with predicted {M}{AB}< 30 will likely be undetectable by JWST. We demonstrate that JWST has the power to discriminate between initial seeding mechanisms.

  1. Lifshitz black holes in IIA supergravity

    NARCIS (Netherlands)

    Barclay, Luke; Gregory, Ruth; Parameswaran, Susha; Tasinato, Gianmassimo; Zavala, Ivonne

    We compute string theoretic black hole solutions having Lifshitz asymptotics with a general dynamical exponent z > 1. We start by constructing solutions in a flux compactification of six dimensional supergravity, then uplift them to massive type HA supergravity. Alongside the Lifshitz black holes we

  2. Surgical solutions to the problem of massive weight loss

    OpenAIRE

    Spector, Jason A; Levine, Steven M; Karp, Nolan S

    2006-01-01

    In response to the global rise in obesity, bariatric surgery has become increasingly more popular and successful. As a result, the demand for body contouring following massive weight loss is rapidly growing. Although bariatric procedures may produce impressive weight loss, people who achieve massive weight loss are often unhappy with the hanging folds of skin and subcutaneous tissue that remain. This review examines the nature of the post-bariatric deformity in each body region and briefly re...

  3. Evolution of massive stars

    International Nuclear Information System (INIS)

    Loore, C. de

    1984-01-01

    The evolution of stars with masses larger than 15 sun masses is reviewed. These stars have large convective cores and lose a substantial fraction of their matter by stellar wind. The treatment of convection and the parameterisation of the stellar wind mass loss are analysed within the context of existing disagreements between theory and observation. The evolution of massive close binaries and the origin of Wolf-Rayet Stars and X-ray binaries is also sketched. (author)

  4. Minimal massive 3D gravity

    NARCIS (Netherlands)

    Bergshoeff, Eric; Hohm, Olaf; Merbis, Wout; Routh, Alasdair J.; Townsend, Paul K.

    2014-01-01

    We present an alternative to topologically massive gravity (TMG) with the same 'minimal' bulk properties; i.e. a single local degree of freedom that is realized as a massive graviton in linearization about an anti-de Sitter (AdS) vacuum. However, in contrast to TMG, the new 'minimal massive gravity'

  5. Superradiantly stable non-extremal Reissner-Nordstroem black holes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jia-Hui [School of Physics and Telecommunication Engineering, South China Normal University, Laboratory of Quantum Engineering and Quantum Materials, Guangzhou (China); Mai, Zhan-Feng [Beijing Normal University, Department of Physics, Center for Advanced Quantum Studies, Beijing (China)

    2016-06-15

    The superradiant stability is investigated for non-extremal Reissner-Nordstroem black holes. We use an algebraic method to demonstrate that all non-extremal Reissner-Nordstroem black holes are superradiantly stable against a charged massive scalar perturbation. This improves the results obtained before for non-extremal Reissner-Nordstroem black holes. (orig.)

  6. Superradiance by mini black holes with mirror

    OpenAIRE

    Lee, Jong-Phil

    2011-01-01

    The superradiant scattering of massive scalar particles by a rotating mini black hole is investigated. Imposing the mirror boundary condition, the system becomes the so called black-hole bomb where the rotation energy of the black hole is transferred to the scattered particle exponentially with time. Bulk emissions as well as brane emissions are considered altogether. It is found that the largest effects are expected for the brane emission of lower angular modes with lighter mass and larger a...

  7. Black hole mergers in the universe

    OpenAIRE

    Zwart, Simon Portegies; McMillan, Stephen

    1999-01-01

    Mergers of black-hole binaries are expected to release large amounts of energy in the form of gravitational radiation. However, binary evolution models predict merger rates too low to be of observational interest. In this paper we explore the possibility that black holes become members of close binaries via dynamical interactions with other stars in dense stellar systems. In star clusters, black holes become the most massive objects within a few tens of millions of years; dynamical relaxation...

  8. CONSTRAINTS ON BLACK HOLE GROWTH, QUASAR LIFETIMES, AND EDDINGTON RATIO DISTRIBUTIONS FROM THE SDSS BROAD-LINE QUASAR BLACK HOLE MASS FUNCTION

    International Nuclear Information System (INIS)

    Kelly, Brandon C.; Hernquist, Lars; Siemiginowska, Aneta; Vestergaard, Marianne; Fan Xiaohui; Hopkins, Philip

    2010-01-01

    We present an estimate of the black hole mass function of broad-line quasars (BLQSOs) that self-consistently corrects for incompleteness and the statistical uncertainty in the mass estimates, based on a sample of 9886 quasars at 1 1 it is highly incomplete at M BH ∼ 9 M sun and L/L Edd ∼ BL > 150 ± 15 Myr for black holes at z = 1 with a mass of M BH = 10 9 M sun , and we constrain the maximum mass of a black hole in a BLQSO to be ∼3 x 10 10 M sun . Our estimated distribution of BLQSO Eddington ratios peaks at L/L Edd ∼ 0.05 and has a dispersion of ∼0.4 dex, implying that most BLQSOs are not radiating at or near the Eddington limit; however, the location of the peak is subject to considerable uncertainty. The steep increase in number density of BLQSOs toward lower Eddington ratios is expected if the BLQSO accretion rate monotonically decays with time. Furthermore, our estimated lifetime and Eddington ratio distributions imply that the majority of the most massive black holes spend a significant amount of time growing in an earlier obscured phase, a conclusion which is independent of the unknown obscured fraction. These results are consistent with models for self-regulated black hole growth, at least for massive systems at z > 1, where the BLQSO phase occurs at the end of a fueling event when black hole feedback unbinds the accreting gas, halting the accretion flow.

  9. Quantum Mechanics of Black Holes

    Science.gov (United States)

    Witten, Edward

    2012-08-01

    The popular conception of black holes reflects the behavior of the massive black holes found by astronomers and described by classical general relativity. These objects swallow up whatever comes near and emit nothing. Physicists who have tried to understand the behavior of black holes from a quantum mechanical point of view, however, have arrived at quite a different picture. The difference is analogous to the difference between thermodynamics and statistical mechanics. The thermodynamic description is a good approximation for a macroscopic system, but statistical mechanics describes what one will see if one looks more closely.

  10. Quantum mechanics of black holes.

    Science.gov (United States)

    Witten, Edward

    2012-08-03

    The popular conception of black holes reflects the behavior of the massive black holes found by astronomers and described by classical general relativity. These objects swallow up whatever comes near and emit nothing. Physicists who have tried to understand the behavior of black holes from a quantum mechanical point of view, however, have arrived at quite a different picture. The difference is analogous to the difference between thermodynamics and statistical mechanics. The thermodynamic description is a good approximation for a macroscopic system, but statistical mechanics describes what one will see if one looks more closely.

  11. The combined effect of AGN and supernovae feedback in launching massive molecular outflows in high-redshift galaxies

    Science.gov (United States)

    Biernacki, Pawel; Teyssier, Romain

    2018-04-01

    We have recently improved our model of active galactic nucleus (AGN) by attaching the supermassive black hole (SMBH) to a massive nuclear star cluster (NSC). Here, we study the effects of this new model in massive, gas-rich galaxies with several simulations of different feedback recipes with the hydrodynamics code RAMSES. These simulations are compared to a reference simulation without any feedback, in which the cooling halo gas is quickly consumed in a burst of star formation. In the presence of strong supernovae (SN) feedback, we observe the formation of a galactic fountain that regulates star formation over a longer period, but without halting it. If only AGN feedback is considered, as soon as the SMBH reaches a critical mass, strong outflows of hot gas are launched and prevent the cooling halo gas from reaching the disc, thus efficiently halting star formation, leading to the so-called `quenching'. If both feedback mechanisms act in tandem, we observe a non-linear coupling, in the sense that the dense gas in the supernovae-powered galactic fountain is propelled by the hot outflow powered by the AGN at much larger radii than without AGN. We argue that these particular outflows are able to unbind dense gas from the galactic halo, thanks to the combined effect of SN and AGN feedback. We speculate that this mechanism occurs at the end of the fast growing phase of SMBH, and is at the origin of the dense molecular outflows observed in many massive high-redshift galaxies.

  12. Searching for the Kinematical Signature of a Black Hole in M87

    OpenAIRE

    Merritt, David; Oh, Siang Peng

    1996-01-01

    Many theories for the formation of massive black holes in galactic nuclei predict that the stellar motions should be anisotropic within the radius of influence of the black hole. We report tentative evidence for such an effect in M87.

  13. Impact analysis on a massively parallel computer

    International Nuclear Information System (INIS)

    Zacharia, T.; Aramayo, G.A.

    1994-01-01

    Advanced mathematical techniques and computer simulation play a major role in evaluating and enhancing the design of beverage cans, industrial, and transportation containers for improved performance. Numerical models are used to evaluate the impact requirements of containers used by the Department of Energy (DOE) for transporting radioactive materials. Many of these models are highly compute-intensive. An analysis may require several hours of computational time on current supercomputers despite the simplicity of the models being studied. As computer simulations and materials databases grow in complexity, massively parallel computers have become important tools. Massively parallel computational research at the Oak Ridge National Laboratory (ORNL) and its application to the impact analysis of shipping containers is briefly described in this paper

  14. On the detection of high-redshift black holes with ALMA through CO and H(2) emission

    NARCIS (Netherlands)

    Spaans, Marco; Meijerink, Rowin

    2008-01-01

    Many present-day galaxies are known to harbor supermassive, >= 10(6) M(circle dot), black holes. These central black holes must have grown through accretion from less massive seeds in the early universe. The molecules CO and H 2 can be used to trace this young population of accreting massive black

  15. Massively Parallel Genetics.

    Science.gov (United States)

    Shendure, Jay; Fields, Stanley

    2016-06-01

    Human genetics has historically depended on the identification of individuals whose natural genetic variation underlies an observable trait or disease risk. Here we argue that new technologies now augment this historical approach by allowing the use of massively parallel assays in model systems to measure the functional effects of genetic variation in many human genes. These studies will help establish the disease risk of both observed and potential genetic variants and to overcome the problem of "variants of uncertain significance." Copyright © 2016 by the Genetics Society of America.

  16. Introduction to massive neutrinos

    International Nuclear Information System (INIS)

    Kayser, B.

    1984-01-01

    We discuss the theoretical ideas which make it natural to expect that neutrinos do indeed have mass. Then we focus on the physical consequences of neutrino mass, including neutrino oscillation and other phenomena whose observation would be very interesting, and would serve to demonstrate that neutrinos are indeed massive. We comment on the legitimacy of comparing results from different types of experiments. Finally, we consider the question of whether neutrinos are their own antiparticles. We explain what this question means, discuss the nature of a neutrino which is its own antiparticles, and consider how one might determine experimentally whether neutrinos are their own antiparticles or not

  17. 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

  18. Electromagnetic field properties in the vicinity of a massive wormhole

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, I. D.; Shatskiy, A. A., E-mail: shatskiy@asc.rssi.ru [Russian Academy of Sciences, Astro Space Centre, Lebedev Physical Institute (Russian Federation)

    2011-12-15

    It is proved that not only massless but also traversable massive wormholes can have electromagnetic 'hair.' An analysis is also presented of the passage from a traversable wormhole to the limit of a Reissner-Nordstroem black hole, with the corresponding disappearance of 'hair.' A general method is developed for solving stationary axisymmetric Maxwell's equations in the field of a massive, spherically symmetric wormhole. As a particular example of application of the method, a solution is found to the axisymmetric magnetostatic problem for a current loop in the field of the Bronnikov-Ellis-Morris-Thorne wormhole.

  19. Growing media [Chapter 5

    Science.gov (United States)

    Douglass F. Jacobs; Thomas D. Landis; Tara Luna

    2009-01-01

    Selecting the proper growing medium is one of the most important considerations in nursery plant production. A growing medium can be defined as a substance through which roots grow and extract water and nutrients. In native plant nurseries, a growing medium can consist of native soil but is more commonly an "artificial soil" composed of materials such as peat...

  20. Phases of massive gravity

    CERN Document Server

    Dubovsky, S L

    2004-01-01

    We systematically study the most general Lorentz-violating graviton mass invariant under three-dimensional Eucledian group using the explicitly covariant language. We find that at general values of mass parameters the massive graviton has six propagating degrees of freedom, and some of them are ghosts or lead to rapid classical instabilities. However, there is a number of different regions in the mass parameter space where massive gravity can be described by a consistent low-energy effective theory with cutoff $\\sim\\sqrt{mM_{Pl}}$ free of rapid instabilities and vDVZ discontinuity. Each of these regions is characterized by certain fine-tuning relations between mass parameters, generalizing the Fierz--Pauli condition. In some cases the required fine-tunings are consequences of the existence of the subgroups of the diffeomorphism group that are left unbroken by the graviton mass. We found two new cases, when the resulting theories have a property of UV insensitivity, i.e. remain well behaved after inclusion of ...

  1. Massively Parallel QCD

    Energy Technology Data Exchange (ETDEWEB)

    Soltz, R; Vranas, P; Blumrich, M; Chen, D; Gara, A; Giampap, M; Heidelberger, P; Salapura, V; Sexton, J; Bhanot, G

    2007-04-11

    The theory of the strong nuclear force, Quantum Chromodynamics (QCD), can be numerically simulated from first principles on massively-parallel supercomputers using the method of Lattice Gauge Theory. We describe the special programming requirements of lattice QCD (LQCD) as well as the optimal supercomputer hardware architectures that it suggests. We demonstrate these methods on the BlueGene massively-parallel supercomputer and argue that LQCD and the BlueGene architecture are a natural match. This can be traced to the simple fact that LQCD is a regular lattice discretization of space into lattice sites while the BlueGene supercomputer is a discretization of space into compute nodes, and that both are constrained by requirements of locality. This simple relation is both technologically important and theoretically intriguing. The main result of this paper is the speedup of LQCD using up to 131,072 CPUs on the largest BlueGene/L supercomputer. The speedup is perfect with sustained performance of about 20% of peak. This corresponds to a maximum of 70.5 sustained TFlop/s. At these speeds LQCD and BlueGene are poised to produce the next generation of strong interaction physics theoretical results.

  2. Massive star evolution

    International Nuclear Information System (INIS)

    Varshavskij, V.I.; Tutukov, A.V.; AN SSSR, Moscow. Astronomicheskij Sovet)

    1975-01-01

    The structure and evolution of 16 (Sun mass), 32 (Sun mass), and 64 (Sun mass) stars with the initial chemical composition X=0.602, Y=0.354, and Z=0.044 (X 12 = 0.00619 and X 16 = 0.01847) are analyzed from the initial main sequence to a complete burnup of oxygen in the nucleus of a red supergiant. At the stage of helium buring in the nucleus the evolutionary track of the star is determined by the equilibrium condition in the zone of varying chemical composition, and at later stages by energy losses due to neutrino emission. In the absence of neutrino emission the external convective zone propagates into regions occupied by the former hydrogen and helium layer sources. This may lead to considerable anomalies in the chemical composition at the star surface and to the decrease of the carbon-oxygen nucleus mass. With regard to neutrino energy losses the structure of layer sources and of the star itself becomes more complicated, thereby increasing the evolution time. Estimation is made of the change in heli.um, carbon, and oxygen contents in the interstellar space over the Galaxy's lifetime as a result of the evolution of massive stars. Some consequences of rotation and meridional circulations are discussed. A study of the structure and evolution of hydrogen-helium massive stars before firing of carbon in the nucleus is made

  3. Two channels of supermassive black hole growth as seen on the galaxies mass-size plane

    Science.gov (United States)

    Krajnović, Davor; Cappellari, Michele; McDermid, Richard M.

    2018-02-01

    We investigate the variation of black hole masses (MBH) as a function of their host galaxy stellar mass (M*) and half-light radius (Re). We confirm that the scatter in MBH within this plane is essentially the same as that in the MBH-σ relation, as expected from the negligible scatter reported in the virial mass estimator σ _v^2=G× M_\\ast /(5× R_e). All variation in MBH happens along lines of constant σv on the (M*, Re) plane, or M* ∝ Re for M* ≲ 2 × 1011 M⊙. This trend is qualitatively the same as those previously reported for galaxy properties related to stellar populations, like age, metallicity, alpha enhancement, mass-to-light ratio and gas content. We find evidence for a change in the MBH variation above the critical mass of Mcrit ≈ 2 × 1011 M⊙. This behaviour can be explained assuming that MBH in galaxies less massive than Mcrit can be predicted by the MBH-σ relation, while MBH in more massive galaxies follows a modified relation, which is also dependent on M* once M* > Mcrit. This is consistent with the scenario where the majority of galaxies grow through star formation, while the most massive galaxies undergo a sequence of dissipation-less mergers. In both channels, black holes and galaxies grow synchronously, giving rise to the black hole-host galaxy scaling relations, but there is no underlying single relation that is universal across the full range of galaxy masses.

  4. Hawking–Page phase transition in new massive gravity

    Directory of Open Access Journals (Sweden)

    Shao-Jun Zhang

    2015-07-01

    Full Text Available We consider Hawking–Page phase transition between the BTZ black hole with M≥0 and the thermal soliton with M=−1 in new massive gravity. By comparing the on-shell free energies, we can see that there exists a critical temperature. The thermal soliton is more probable than the black hole below the critical temperature while the black hole is more probable than the thermal soliton above the critical temperature. By consistently constructing the off-shell free energies taking into account the conical singularity, we show that there exist infinite non-equilibrium states connecting the BTZ black hole and the thermal soliton, so that they provide a picture of continuous evolution of the phase transition.

  5. On Quantum Contributions to Black Hole Growth

    NARCIS (Netherlands)

    Spaans, M.

    2013-01-01

    The effects of Wheeler’s quantum foam on black hole growth are explored from an astrophysical per- spective. Quantum fluctuations in the form of mini (10−5 g) black holes can couple to macroscopic black holes and allow the latter to grow exponentially in mass on a time scale of 109 years.

  6. Black Alcoholism.

    Science.gov (United States)

    Watts, Thomas D.; Wright, Roosevelt

    1988-01-01

    Examines some aspects of the problem of alcoholism among Blacks, asserting that Black alcoholism can best be considered in an ecological, environmental, sociocultural, and public health context. Notes need for further research on alcoholism among Blacks and for action to reduce the problem of Black alcoholism. (NB)

  7. Black Culture

    Science.gov (United States)

    Brown, Angela Khristin

    2013-01-01

    The migration of blacks in North America through slavery became united. The population of blacks passed down a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape…

  8. Massive Galileon positivity bounds

    Science.gov (United States)

    de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong

    2017-09-01

    The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.

  9. Massively parallel multicanonical simulations

    Science.gov (United States)

    Gross, Jonathan; Zierenberg, Johannes; Weigel, Martin; Janke, Wolfhard

    2018-03-01

    Generalized-ensemble Monte Carlo simulations such as the multicanonical method and similar techniques are among the most efficient approaches for simulations of systems undergoing discontinuous phase transitions or with rugged free-energy landscapes. As Markov chain methods, they are inherently serial computationally. It was demonstrated recently, however, that a combination of independent simulations that communicate weight updates at variable intervals allows for the efficient utilization of parallel computational resources for multicanonical simulations. Implementing this approach for the many-thread architecture provided by current generations of graphics processing units (GPUs), we show how it can be efficiently employed with of the order of 104 parallel walkers and beyond, thus constituting a versatile tool for Monte Carlo simulations in the era of massively parallel computing. We provide the fully documented source code for the approach applied to the paradigmatic example of the two-dimensional Ising model as starting point and reference for practitioners in the field.

  10. Bold but Irrelevant: Grow and Shapiro on Transracial Adoption

    Science.gov (United States)

    Chimezie, Amuzie

    1977-01-01

    This critique of the Grow-Shapiro study entitled "Black Children--White Parents" A Study of Transracial Adoption" reviews and unfavorably critizes the study and suggests alternative ways of approaching the topic. (MS)

  11. Massive Cervico-Lingual Cystic Hygroma | Odhiambo | Annals of ...

    African Journals Online (AJOL)

    Cystic Hygroma (CH) is an aberrant proliferation of lymphatic vessels creating fluid-filled sacs that result from blockage in the abnormal lymphatic system. These benign lesions are characteristic in their capability to grow to an enormously huge size has potential pressure effects on the neighboring structures. The massive ...

  12. Black Holes Lead Galaxy Growth, New Research Shows

    Science.gov (United States)

    2009-01-01

    as they were in the first billion years after the Big Bang, and the evidence suggests that the constant ratio seen nearby may not hold in the early Universe. The black holes in these young galaxies are much more massive compared to the bulges than those seen in the nearby Universe," said Fabian Walter of the Max-Planck Institute for Astronomy (MPIfA) in Germany. "The implication is that the black holes started growing first." The next challenge is to figure out how the black hole and the bulge affect each others' growth. "We don't know what mechanism is at work here, and why, at some point in the process, the 'standard' ratio between the masses is established," Riechers said. New telescopes now under construction will be key tools for unraveling this mystery, Carilli explained. "The Expanded Very Large Array (EVLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) will give us dramatic improvements in sensitivity and the resolving power to image the gas in these galaxies on the small scales required to make detailed studies of their dynamics," he said. "To understand how the Universe got to be the way it is today, we must understand how the first stars and galaxies were formed when the Universe was young. With the new observatories we'll have in the next few years, we'll have the opportunity to learn important details from the era when the Universe was only a toddler compared to today's adult," Carilli said. Carilli, Riechers and Walter worked with Frank Bertoldi of Bonn University; Karl Menten of MPIfR; and Pierre Cox and Roberto Neri of the Insitute for Millimeter Radio Astronomy (IRAM) in France.

  13. The Final Stages of Massive Star Evolution and Their Supernovae

    Science.gov (United States)

    Heger, Alexander

    In this chapter I discuss the final stages in the evolution of massive stars - stars that are massive enough to burn nuclear fuel all the way to iron group elements in their core. The core eventually collapses to form a neutron star or a black hole when electron captures and photo-disintegration reduce the pressure support to an extent that it no longer can hold up against gravity. The late burning stages of massive stars are a rich subject by themselves, and in them many of the heavy elements in the universe are first generated. The late evolution of massive stars strongly depends on their mass, and hence can be significantly effected by mass loss due to stellar winds and episodic mass loss events - a critical ingredient that we do not know as well as we would like. If the star loses all the hydrogen envelope, a Type I supernova results, if it does not, a Type II supernova is observed. Whether the star makes neutron star or a black hole, or a neutron star at first and a black hole later, and how fast they spin largely affects the energetics and asymmetry of the observed supernova explosion. Beyond photon-based astronomy, other than the sun, a supernova (SN 1987) has been the only object in the sky we ever observed in neutrinos, and supernovae may also be the first thing we will ever see in gravitational wave detectors like LIGO. I conclude this chapter reviewing the deaths of the most massive stars and of Population III stars.

  14. A discrete ordinate response matrix method for massively parallel computers

    International Nuclear Information System (INIS)

    Hanebutte, U.R.; Lewis, E.E.

    1991-01-01

    A discrete ordinate response matrix method is formulated for the solution of neutron transport problems on massively parallel computers. The response matrix formulation eliminates iteration on the scattering source. The nodal matrices which result from the diamond-differenced equations are utilized in a factored form which minimizes memory requirements and significantly reduces the required number of algorithm utilizes massive parallelism by assigning each spatial node to a processor. The algorithm is accelerated effectively by a synthetic method in which the low-order diffusion equations are also solved by massively parallel red/black iterations. The method has been implemented on a 16k Connection Machine-2, and S 8 and S 16 solutions have been obtained for fixed-source benchmark problems in X--Y geometry

  15. Schwarzschild black holes can wear scalar wigs.

    Science.gov (United States)

    Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Núñez, Darío; Sarbach, Olivier

    2012-08-24

    We study the evolution of a massive scalar field surrounding a Schwarzschild black hole and find configurations that can survive for arbitrarily long times, provided the black hole or the scalar field mass is small enough. In particular, both ultralight scalar field dark matter around supermassive black holes and axionlike scalar fields around primordial black holes can survive for cosmological times. Moreover, these results are quite generic in the sense that fairly arbitrary initial data evolve, at late times, as a combination of those long-lived configurations.

  16. Horizon of quantum black holes in various dimensions

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2016-09-01

    Full Text Available We adapt the horizon wave-function formalism to describe massive static spherically symmetric sources in a general (1+D-dimensional space-time, for D>3 and including the D=1 case. We find that the probability PBH that such objects are (quantum black holes behaves similarly to the probability in the (3+1 framework for D>3. In fact, for D≥3, the probability increases towards unity as the mass grows above the relevant D-dimensional Planck scale mD. At fixed mass, however, PBH decreases with increasing D, so that a particle with mass m≃mD has just about 10% probability to be a black hole in D=5, and smaller for larger D. This result has a potentially strong impact on estimates of black hole production in colliders. In contrast, for D=1, we find the probability is comparably larger for smaller masses, but PBH3. For D=1 we instead find the uncertainty due to the horizon fluctuations has the same form as the usual Heisenberg contribution, and therefore no fundamental scale exists.

  17. Massive Gravity in Three Dimensions

    NARCIS (Netherlands)

    Bergshoeff, Eric A.; Hohm, Olaf; Townsend, Paul K.

    2009-01-01

    A particular higher-derivative extension of the Einstein-Hilbert action in three spacetime dimensions is shown to be equivalent at the linearized level to the (unitary) Pauli-Fierz action for a massive spin-2 field. A more general model, which also includes "topologically-massive" gravity as a

  18. Evolution and fate of very massive objects

    International Nuclear Information System (INIS)

    Bond, J.R.; Arnett, W.D.; Carr, B.J.

    1984-01-01

    The structure and evolution of Very Massive Objects (stars of mass approx.10 2 -10 5 M/sub sun/) are discussed in terms of simple semianalytic models. We estimate the helium enrichment due to mass loss, and present evidence for a dynamical instability arising in the hydrogen shell burning phase of a 500 M/sub sun/ Population I star. The fate of a VMO is decided in its oxygen core phase, Calculations of the effects of the pair instability, oxygen and silicon burning, and alpha-quenching on the global binding energy of initially isentropic polytropic cores allow us to predict the critical oxygen core mass above which complete collapse to a black hole occurs: M/sub O//sub c/roughly-equal10 2 M/sub sun/ corresponding to an initial star mass greater than 200 M/sub sun/. Cores smaller than this explode; we estimate the kinetic energy liberated

  19. Softly Massive Gravity

    CERN Document Server

    Gabadadze, Gregory T

    2004-01-01

    Large-distance modification of gravity may be the mechanism for solving the cosmological constant problem. A simple model of the large-distance modification -- four-dimensional (4D) gravity with the hard mass term-- is problematic from the theoretical standpoint. Here we discuss a different model, the brane-induced gravity, that effectively introduces a soft graviton mass. We study the issues of unitarity, analyticity and causality in this model in more than five dimensions. We show that a consistent prescription for the poles of the Green's function can be specified so that 4D unitarity is preserved. However, in certain instances 4D analyticity cannot be maintained when theory becomes higher dimensional. As a result, one has to sacrifice 4D causality at distances of the order of the present-day Hubble scale. This is a welcome feature for solving the cosmological constant problem, as was recently argued in the literature. We also show that, unlike the 4D massive gravity, the model has no strong-coupling probl...

  20. Never Before Seen: Two Supermassive Black Holes in Same Galaxy

    Science.gov (United States)

    2002-11-01

    For the first time, scientists have proof two supermassive black holes exist together in the same galaxy, thanks to data from NASA's Chandra X-ray Observatory. These black holes are orbiting each other and will merge several hundred million years from now, to create an even larger black hole resulting in a catastrophic event that will unleash intense radiation and gravitational waves. The Chandra image reveals that the nucleus of an extraordinarily bright galaxy, known as NGC 6240, contains not one, but two giant black holes, actively accreting material from their surroundings. This discovery shows that massive black holes can grow through mergers in the centers of galaxies, and that these enigmatic events will be detectable with future space-borne gravitational wave observatories. "The breakthrough came with Chandra's ability to clearly distinguish the two nuclei, and measure the details of the X-radiation from each nucleus," said Guenther Hasinger, of the Max Planck Institute for Extraterrestrial Physics in Germany, a coauthor of an upcoming Astrophysical Journal Letters paper describing the research. "These cosmic fingerprints revealed features characteristic of supermassive black holes -- an excess of high-energy photons from gas swirling around a black hole, and X-rays from fluorescing iron atoms in gas near black holes," he said. Previous X-ray observatories had shown that the central region produces X-rays, while radio, infrared and optical observations had detected two bright nuclei, but the nature of this region remained a mystery. Astronomers did not know the location of the X-ray source, or the nature of the two bright nuclei. "With Chandra, we hoped to determine which one, if either, of the nuclei was an active supermassive black hole," said Stefanie Komossa, also of the Max Planck Institute, lead author of the paper on NGC 6240. "Much to our surprise, we found that both were active black holes!" At a distance of about 400 million light years, NGC 6240

  1. The formation of bulges and black holes: lessons from a census of active galaxies in the SDSS.

    Science.gov (United States)

    Kauffmann, Guinevere; Heckman, Timothy M

    2005-03-15

    We examine the relationship between galaxies, supermassive black holes and AGN using a sample of 23,000 narrow-emission-line ('type 2') active galactic nuclei (AGN) drawn from a sample of 123,000 galaxies from the Sloan Digital Sky Survey. We have studied how AGN host properties compare with those of normal galaxies and how they depend on the luminosity of the active nucleus. We find that AGN reside in massive galaxies and have distributions of sizes and concentrations that are similar to those of the early-type galaxies in our sample. The host galaxies of low-luminosity AGN have stellar populations similar to normal early types. The hosts of high- luminosity AGN have much younger mean stellar ages, and a significant fraction have experienced recent starbursts. High-luminosity AGN are also found in lower-density environments. We then use the stellar velocity dispersions of the AGN hosts to estimate black hole masses and their [OIII]lambda5007 emission-line luminosities to estimate black hole accretion rates. We find that the volume averaged ratio of star formation to black hole accretion is approximately 1000 for the bulge-dominated galaxies in our sample. This is remarkably similar to the observed ratio of stellar mass to black hole mass in nearby bulges. Most of the present-day black hole growth is occurring in black holes with masses less than 3 x 10(7)M(3). Our estimated accretion rates imply that low-mass black holes are growing on a time-scale that is comparable with the age of the Universe. Around 50% this growth takes place in AGN that are radiating within a factor of five of the Eddington luminosity. Such systems are rare, making up only 0.2% of the low-mass black hole population at the present day. The remaining growth occurs in lower luminosity AGN. The growth time-scale increases by more than an order of magnitude for the most massive black holes in our sample. We conclude that the evolution of the AGN luminosity function documented in recent optical

  2. Anaesthetic management of a child with massive extracranial arteriovenous malformation

    Directory of Open Access Journals (Sweden)

    Faisal Shamim

    2012-01-01

    Full Text Available Vascular tumors affect the head and neck commonly but arteriovenous malformations are rare. Vascular malformations are often present at birth and grow with the patient, usually only becoming significant later in childhood. Embolization has been the mainstay of treatment in massive and complex arteriovenous malformations. We present a case of massive extracranial arteriovenous malformation in a 7-year-old boy causing significant workload on right heart and respiratory distress. The management of angioembolization under general anaesthesia and anaesthetic concerns are presented.

  3. Coordination of massively concurrent activities

    NARCIS (Netherlands)

    F. Arbab (Farhad)

    1995-01-01

    textabstractMassively parallel and distributed systems open new horizons for large applications and present new challenges for software technology. Many applications already take advantage of the increased raw computational power provided by such parallel systems to yield significantly shorter

  4. THE RELATION BETWEEN COMPACT, QUIESCENT HIGH-REDSHIFT GALAXIES AND MASSIVE NEARBY ELLIPTICAL GALAXIES: EVIDENCE FOR HIERARCHICAL, INSIDE-OUT GROWTH

    International Nuclear Information System (INIS)

    Bezanson, Rachel; Van Dokkum, Pieter G.; Tal, Tomer; Marchesini, Danilo; Coppi, Paolo; Kriek, Mariska; Franx, Marijn

    2009-01-01

    Recent studies have shown that massive quiescent galaxies at high redshift are much more compact than present-day galaxies of the same mass. Here we compare the radial stellar density profiles and the number density of a sample of massive galaxies at z ∼ 2.3 to nearby massive elliptical galaxies. We confirm that the average stellar densities of the z ∼ 2.3 galaxies within the effective radius, ρ( e ), are two orders of magnitude higher than those of local elliptical galaxies of the same stellar mass. However, we also find that the densities measured within a constant physical radius of 1 kpc, ρ( 1+2 /r 1 ) ∼ (M 1+2 /M 1 ) 2 . A simple model where compact galaxies with masses ∼10 11 M sun primarily grow through minor mergers produces descendants with the approximate sizes, stellar densities, and number density of elliptical galaxies with masses 2-3 x 10 11 M sun in the local universe. We note that this model also predicts evolution in the M BH - σ relation, such that the progenitors of elliptical galaxies have lower black hole masses at fixed velocity dispersion. The main observational uncertainty is the conversion from light to mass; measurements of kinematics are needed to calibrate the masses and stellar densities of the high-redshift galaxies.

  5. Massive gravity from bimetric gravity

    International Nuclear Information System (INIS)

    Baccetti, Valentina; Martín-Moruno, Prado; Visser, Matt

    2013-01-01

    We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. (paper)

  6. Black Holes Shed Light on Galaxy Formation

    Science.gov (United States)

    2000-01-01

    This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.

  7. Magnetic resonance imaging of massive bone allografts with histologic correlation

    International Nuclear Information System (INIS)

    Hoeffner, E.G.; Soulen, R.L.; Ryan, J.R.; Qureshi, F.

    1996-01-01

    The objective of this study was to better understand the MRI appearance of massive bone allografts. The MRI findings of three massive bone allografts imaged in vivo were correlated with the histologic findings following removal of the allografts. A fourth allograft, never implanted, was imaged and evaluated histologically. Allografts were placed for the treatment of primary or recurrent osteosarcoma. The in-vivo allografts have a heterogeneous appearance on MRI which we attribute to the revascularization process. Fibrovascular connective tissue grows into the graft in a patchy, focal fashion, down the medullary canal from the graft-host junction and adjacent to the periosteum. The marrow spaces are initially devoid of normal cellular elements and occupied by fat and gelatinous material. This normal postoperative appearance of massive bone allografts must not be interpreted as recurrent neoplasm or infection in the allograft. Recognition of these complications rests on features outside the marrow. (orig./MG)

  8. Giant black hole rips star apart

    Science.gov (United States)

    2004-02-01

    amount is consistent with predictions that the momentum and energy of the accretion process will cause most of the destroyed star's gas to be flung away from the black hole. The force that disrupted the star in RXJ1242-11 is an extreme example of the tidal force caused by differences in gravity acting on the front and back of an object. The tidal force from the Moon causes tides in the oceans on Earth, and tidal force from Jupiter pulled Comet Shoemaker-Levy apart before it plunged into the giant planet. The odds that stellar tidal disruption will happen in a typical galaxy are long, about one in ten thousand. If it happened at the centre of the Milky Way, the resulting X-ray source would be about 50 000 times more powerful than the strongest X-ray source in our galaxy. However, such an event would not pose a threat to Earth because of the intervening distance of 25 000 light years. Other dramatic flares have been seen from galaxies, but this is the first to have been studied with the high spectral resolution of XMM-Newton and the high spatial resolution of Chandra. Both instruments have made a critical advance. Chandra showed that the RXJ1242-11 event occurred in the centre of a galaxy, where the black hole lurks. The XMM-Newton spectrum revealed the fingerprints expected for the surroundings of a black hole, and allowed other possible astronomical explanations to be ruled out. Evidence already exists for super-massive black holes in many galaxies, but looking for tidal disruptions represents a completely independent way to search for black holes. Observations like these are urgently needed to determine how quickly black holes can grow by swallowing neighbouring stars. Notes to editors This discovery was announced today at a press conference at NASA Headquarters in Washington DC, USA. A paper describing these results, by Stefanie Komossa and others, will be published in The Astrophysical Journal. ESA’s XMM-Newton can detect more X-ray sources than any previous

  9. Quasinormal modes for massless topological black holes

    International Nuclear Information System (INIS)

    Aros, Rodrigo; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge

    2003-01-01

    An exact expression for the quasinormal modes of scalar perturbation on a massless topological black hole in four and higher dimensions is presented. The massive scalar field is nonminimally coupled to the curvature, and the horizon geometry is assumed to have a negative constant curvature

  10. Black Hole Complementarity and Violation of Causality

    OpenAIRE

    Rozenblit, Moshe

    2017-01-01

    Analysis of a massive shell collapsing on a solid sphere shows that black hole complementarity (BHC) violates causality in its effort to save information conservation. In particular, this note describes a hypothetical contraption based on BHC that would allow the transfer of information from the future to the present.

  11. The Role of Primordial Kicks on Black Hole Merger Rates

    OpenAIRE

    Micic, Miroslav; Abel, Tom; Sigurdsson, Steinn

    2006-01-01

    Primordial stars are likely to be very massive >30 Msun, form in isolation, and will likely leave black holes as remnants in the centers of their host dark matter halos. We expect primordial stars to form in halos in the mass range 10^6-10^10 Msun. Some of these early black holes, formed at redshifts z>10, could be the seed black hole for a significant fraction of the supermassive black holes found in galaxies in the local universe. If the black hole descendants of the primordial stars exist,...

  12. Fluorescent bands in massive corals record centuries of coastal rainfall

    Science.gov (United States)

    Isdale, Peter

    1984-08-01

    Massive coral colonies on the Great Barrier Reef grow outwards at 5-25 mm yr-1 (ref. 1). Skeletal density varies seasonally in all massive corals from the Great Barrier Reef and an exact temporal record of growth can be obtained by X-radiography of appropriately cut sections of the colony2,3. Environmental influences on coral growth have been described from such analyses4-6. This is the first report from the skeletons of massive corals of yellow green fluorescent bands which appear under long-wave UV light. Such fluorescence is confined to corals growing within 20 km of the shore and is not present in massive corals from mid- and outer shelf reefs of the central Great Barrier Reef region. The timing, width and intensity of the fluorescent bands correlate strongly with summer, monsoonal rainfall and coastal runoff. Large colonies, several centuries old, can provide long records of the strength and periodicity of terrestrial runoff to the tropical nearshore environment. Such records are potentially important to climatology, meteorology, agriculture, civil engineering and management of the Great Barrier Reef.

  13. Black Culture

    Directory of Open Access Journals (Sweden)

    Angela Khristin Brown

    2013-07-01

    Full Text Available The migration of blacks in North America through slavery became united.  The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life.

  14. Role of primordial black holes in the direct collapse scenario of ...

    Indian Academy of Sciences (India)

    In this paper, we explore the possibility of accreting primordial black holes as the source of heating for the collapsing gas in the context of the direct collapse black hole scenario for the formation of super-massive black holes (SMBHs) at high redshifts, z ∼ 6 – 7 . One of the essential requirements for the direct collapse model ...

  15. Rotating black holes can have short bristles

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2014-12-01

    Full Text Available The elegant ‘no short hair’ theorem states that, if a spherically-symmetric static black hole has hair, then this hair must extend beyond 3/2 the horizon radius. In the present paper we provide evidence for the failure of this theorem beyond the regime of spherically-symmetric static black holes. In particular, we show that rotating black holes can support extremely short-range stationary scalar configurations (linearized scalar ‘clouds’ in their exterior regions. To that end, we solve analytically the Klein–Gordon–Kerr–Newman wave equation for a linearized massive scalar field in the regime of large scalar masses.

  16. Black-hole Merger Simulations for LISA Science

    Science.gov (United States)

    Kelly, Bernard J.; Baker, John G.; vanMeter, James R.; Boggs, William D.; Centrella, Joan M.; McWilliams, Sean T.

    2009-01-01

    The strongest expected sources of gravitational waves in the LISA band are the mergers of massive black holes. LISA may observe these systems to high redshift, z>10, to uncover details of the origin of massive black holes, and of the relationship between black holes and their host structures, and structure formation itself. These signals arise from the final stage in the development of a massive black-hole binary emitting strong gravitational radiation that accelerates the system's inspiral toward merger. The strongest part of the signal, at the point of merger, carries much information about the system and provides a probe of extreme gravitational physics. Theoretical predictions for these merger signals rely on supercomputer simulations to solve Einstein's equations. We discuss recent numerical results and their impact on LISA science expectations.

  17. Black holes in the universe

    International Nuclear Information System (INIS)

    Camenzind, M.

    2005-01-01

    While physicists have been grappling with the theory of black holes (BH), as shown by the many contributions to the Einstein year, astronomers have been successfully searching for real black holes in the Universe. Black hole astrophysics began in the 1960s with the discovery of quasars and other active galactic nuclei (AGN) in distant galaxies. Already in the 1960s it became clear that the most natural explanation for the quasar activity is the release of gravitational energy through accretion of gas onto supermassive black holes. The remnants of this activity have now been found in the centers of about 50 nearby galaxies. BH astrophysics received a new twist in the 1970s with the discovery of the X-ray binary (XRB) Cygnus X-1. The X-ray emitting compact object was too massive to be explained by a neutron star. Today, about 20 excellent BH candidates are known in XRBs. On the extragalactic scale, more than 100.000 quasars have been found in large galaxy surveys. At the redshift of the most distant ones, the Universe was younger than one billion year. The most enigmatic black hole candidates identified in the last years are the compact objects behind the Gamma-Ray Bursters. The formation of all these types of black holes is accompanied by extensive emission of gravitational waves. The detection of these strong gravity events is one of the biggest challenges for physicists in the near future. (author)

  18. Condensate of massive graviton and dark matter

    OpenAIRE

    Aoki, Katsuki; Maeda, Kei-ichi

    2018-01-01

    We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first define the effective energy-momentum tensor of the coherent massive gravitons in a curved spacetime. We then study the background dynamics of the universe and the cosmic structure formation including the effects of the coherent massive gravitons. We find that the condensate of the massive graviton behaves as a dark matt...

  19. Chaotic cold accretion on to black holes in rotating atmospheres

    Science.gov (United States)

    Gaspari, M.; Brighenti, F.; Temi, P.

    2015-07-01

    The fueling of black holes is one key problem in the evolution of baryons in the universe. Chaotic cold accretion (CCA) profoundly differs from classic accretion models, as Bondi and thin disc theories. Using 3D high-resolution hydrodynamic simulations, we now probe the impact of rotation on the hot and cold accretion flow in a typical massive galaxy. In the hot mode, with or without turbulence, the pressure-dominated flow forms a geometrically thick rotational barrier, suppressing the black hole accretion rate to ~1/3 of the spherical case value. When radiative cooling is dominant, the gas loses pressure support and quickly circularizes in a cold thin disk; the accretion rate is decoupled from the cooling rate, although it is higher than that of the hot mode. In the more common state of a turbulent and heated atmosphere, CCA drives the dynamics if the gas velocity dispersion exceeds the rotational velocity, i.e., turbulent Taylor number Tat 1), the broadening of the distribution and the efficiency of collisions diminish, damping the accretion rate ∝ Tat-1, until the cold disk drives the dynamics. This is exacerbated by the increased difficulty to grow TI in a rotating halo. The simulated sub-Eddington accretion rates cover the range inferred from AGN cavity observations. CCA predicts inner flat X-ray temperature and r-1 density profiles, as recently discovered in M 87 and NGC 3115. The synthetic Hα images reproduce the main features of cold gas observations in massive ellipticals, as the line fluxes and the filaments versus disk morphology. Such dichotomy is key for the long-term AGN feedback cycle. As gas cools, filamentary CCA develops and boosts AGN heating; the cold mode is thus reduced and the rotating disk remains the sole cold structure. Its consumption leaves the atmosphere in hot mode with suppressed accretion and feedback, reloading the cycle.

  20. Black Hole Mergers in the Universe.

    Science.gov (United States)

    Portegies Zwart SF; McMillan

    2000-01-01

    Mergers of black hole binaries are expected to release large amounts of energy in the form of gravitational radiation. However, binary evolution models predict merger rates that are too low to be of observational interest. In this Letter, we explore the possibility that black holes become members of close binaries via dynamical interactions with other stars in dense stellar systems. In star clusters, black holes become the most massive objects within a few tens of millions of years; dynamical relaxation then causes them to sink to the cluster core, where they form binaries. These black hole binaries become more tightly bound by superelastic encounters with other cluster members and are ultimately ejected from the cluster. The majority of escaping black hole binaries have orbital periods short enough and eccentricities high enough that the emission of gravitational radiation causes them to coalesce within a few billion years. We predict a black hole merger rate of about 1.6x10-7 yr-1 Mpc-3, implying gravity-wave detection rates substantially greater than the corresponding rates from neutron star mergers. For the first-generation Laser Interferometer Gravitational-Wave Observatory (LIGO-I), we expect about one detection during the first 2 years of operation. For its successor LIGO-II, the rate rises to roughly one detection per day. The uncertainties in these numbers are large. Event rates may drop by about an order of magnitude if the most massive clusters eject their black hole binaries early in their evolution.

  1. Key Technologies in Massive MIMO

    Directory of Open Access Journals (Sweden)

    Hu Qiang

    2018-01-01

    Full Text Available The explosive growth of wireless data traffic in the future fifth generation mobile communication system (5G has led researchers to develop new disruptive technologies. As an extension of traditional MIMO technology, massive MIMO can greatly improve the throughput rate and energy efficiency, and can effectively improve the link reliability and data transmission rate, which is an important research direction of 5G wireless communication. Massive MIMO technology is nearly three years to get a new technology of rapid development and it through a lot of increasing the number of antenna communication, using very duplex communication mode, make the system spectrum efficiency to an unprecedented height.

  2. Black holes in the early Universe.

    Science.gov (United States)

    Volonteri, Marta; Bellovary, Jillian

    2012-12-01

    The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of MBHs. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of MBHs. What physical mechanisms led to the formation of the first MBHs? How massive were the initial MBH seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? The answers to most of these questions are works in progress, in the spirit of these reports on progress in physics.

  3. Black holes in the early Universe

    International Nuclear Information System (INIS)

    Volonteri, Marta; Bellovary, Jillian

    2012-01-01

    The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of MBHs. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of MBHs. What physical mechanisms led to the formation of the first MBHs? How massive were the initial MBH seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? The answers to most of these questions are works in progress, in the spirit of these reports on progress in physics. (review article)

  4. Black Cohosh

    Science.gov (United States)

    ... who have had hormone-sensitive conditions such as breast cancer or for pregnant women or nursing mothers. Black cohosh should not be confused with blue cohosh (Caulophyllum thalictroides) , which has different effects and may not be safe. Black cohosh has ...

  5. Researchers Resolve Intermediate Mass Black Hole Mystery

    Science.gov (United States)

    2004-04-01

    New research, funded by the Royal Netherlands Academy of Sciences, the Institute of Advanced Physical and Chemical Research, NASA and the University of Tokyo, solved the mystery of how a black hole, with the mass more than several hundreds times larger than that of our Sun, could be formed in the nearby starburst galaxy, M82. Recent observations of the Chandra X-ray observatory (Matsumoto et al., 2001 ApJ 547, L25) indicate the presence of an unusually bright source in the star cluster MGG11 in the starburst galaxy M82. The properties of the X-ray source are best explained by a black hole with a mass of about a thousand times the mass of the Sun, placing it intermediate between the relatively small (stellar mass) black holes in the Milky way Galaxy and the supermassive black holes found in the nuclei of galaxies. For comparison, stellar-mass black holes are only a few times more massive than the Sun, whereas the black hole in the center of the Milky-way Galaxy is more than a few million times more massive than the Sun. An international team of researchers, using the world's fastest computer, the GRAPE-6 system in Japan, were engaged in a series of simulations of star clusters that resembled MGG11. They used the GRAPE-6 to perform simulations with two independently developed computer programs (Starlab and NBODY4 developed by Sverre Aarseth in Cambridge), both of which give the same qualitative result. The simulations ware initiated by high resolution observations of the star cluster MGG11 by McCrady et al (2003, ApJ 596, 240) using the Hubble Space Telescope and Keck, and by Harashima et al (2001) using the giant Subaru telescope. M82 Chandra X-ray image of the central region of the starburst galaxy M82. The GRAPE's detailed, star-by-star simulations represent the state of the art in cluster modeling. For the first time using the GRAPE, researchers perform simulations of the evolution of young and dense star clusters with up to 600000 stars; they calculate the

  6. Relativistic three-body effects in black hole coalescence

    International Nuclear Information System (INIS)

    Campanelli, Manuela; Dettwyler, Miranda; Lousto, Carlos O.; Hannam, Mark

    2006-01-01

    Three-body interactions are expected to be common in globular clusters and in galactic cores hosting supermassive black holes. We consider an equal-mass binary black hole system in the presence of a third black hole. Using numerically generated binary black hole initial data sets, and first and second-order post-Newtonian (1PN and 2PN) techniques, we find that the presence of the third black hole has non-negligible relativistic effects on the location of the binary's innermost stable circular orbit (ISCO), and that these effects arise at 2PN order. For a stellar-mass black hole binary in orbit about a supermassive black hole, the massive black hole has stabilizing effects on the orbiting binary, leading to an increase in merger time and a decrease of the terminal orbital frequency, and an amplification of the gravitational radiation emitted from the binary system by up to 6%

  7. Model problems for gravitationally perturbed black holes

    International Nuclear Information System (INIS)

    Price, R.H.; Thorne, K.S.; Macdonald, D.A.; Crowley, R.J.; Redmount, I.H.

    1986-01-01

    The membrane formalism is applied to various types of gravitational perturbations of a black hole. Attention is given to the disturbance of the horizon of a black hole by compact masses lowered toward a nonrotating hole and the deformations experienced by a rotating hole. Nonaxisymmetric gravitational tidal fields in rigid motion about a rotating hole are considered, along with the behavior of massive particle moving along the equator of a rotating hole, and the spindown of a rotating hole in an external tidal field. The extraction of rotational energy from a black hole by orbiting bodies is examined, as are superradiant scattering of gravitational waves and the quasi-normal modes of a black hole. The perturbations imparted to a black hole by a compact body plunging into the membrane (a stretched horizon) at a velocity close to the local light speed and by a radially accelerated particle above the horizon of a nonrotating hole are also explored

  8. Abdominal Compartment Syndrome complicating massive ...

    African Journals Online (AJOL)

    shobha

    cycle. Unless the Intra-abdominal pressure is reduced quickly by urgent surgical or medical interventions, death is inevitable. We report a case of ACS resulting from an unrecognized slow but massive intra-abdominal bleeding caused by a ruptured ectopic pregnancy (REP) in an Arab woman. Due to the unusual nature of ...

  9. Massively parallel quantum computer simulator

    NARCIS (Netherlands)

    De Raedt, K.; Michielsen, K.; De Raedt, H.; Trieu, B.; Arnold, G.; Richter, M.; Lippert, Th.; Watanabe, H.; Ito, N.

    2007-01-01

    We describe portable software to simulate universal quantum computers on massive parallel Computers. We illustrate the use of the simulation software by running various quantum algorithms on different computer architectures, such as a IBM BlueGene/L, a IBM Regatta p690+, a Hitachi SR11000/J1, a Cray

  10. Massive subcutaneous emphysema with pneumoscrotopenis ...

    African Journals Online (AJOL)

    Chest injury commonly leads to subcutaneous emphysema of the chest, neck and face. It is usually non-life threatening. Massive subcutaneous emphysema may occur and very rarely may spread to involve the scrotal sac and subcutaneous tissue planes of the penis to cause pneumoscrotopenis. This case report presents ...

  11. A massively parallel discrete ordinates response matrix method for neutron transport

    International Nuclear Information System (INIS)

    Hanebutte, U.R.; Lewis, E.E.

    1992-01-01

    In this paper a discrete ordinates response matrix method is formulated with anisotropic scattering for the solution of neutron transport problems on massively parallel computers. The response matrix formulation eliminates iteration on the scattering source. The nodal matrices that result from the diamond-differenced equations are utilized in a factored form that minimizes memory requirements and significantly reduces the number of arithmetic operations required per node. The red-black solution algorithm utilizes massive parallelism by assigning each spatial node to one or more processors. The algorithm is accelerated by a synthetic method in which the low-order diffusion equations are also solved by massively parallel red-black iterations. The method is implemented on a 16K Connection Machine-2, and S 8 and S 16 solutions are obtained for fixed-source benchmark problems in x-y geometry

  12. WHEN COMPASSION GROWS WINGS

    African Journals Online (AJOL)

    Nicky

    antiretroviral roll-out in full swing, the. WHEN COMPASSION GROWS WINGS. The free time and expertise given by its deeply committed core of professional volunteers. (including pilots) is the lifeblood of the operation. Red Cross Air Mercy Service volunteer, German national Dr Florian Funk, at the AMS Durban base.

  13. Growing Plants and Minds

    Science.gov (United States)

    Presser, Ashley Lewis; Kamdar, Danae; Vidiksis, Regan; Goldstein, Marion; Dominguez, Ximena; Orr, Jillian

    2017-01-01

    Many preschool classrooms explore plant growth. However, because many plants take a long time to grow, it is often hard to facilitate engagement in some practices (i.e., since change is typically not observable from one day to another, children often forget their prior predictions or cannot recall what plants looked like days or weeks earlier).…

  14. On the instability regime of the rotating Kerr spacetime to massive scalar perturbations

    International Nuclear Information System (INIS)

    Hod, Shahar

    2012-01-01

    The instability of rotating Kerr black holes due to massive scalar perturbations is investigated. It is well known that a bosonic field impinging on a Kerr black hole can be amplified as it scatters off the hole. This superradiant scattering occurs for frequencies in the range ω< mΩ, where Ω is the angular frequency of the black hole and m is the azimuthal harmonic index of the mode. If the incident field has a non-zero rest mass, μ, then the mass term effectively works as a mirror, reflecting the scattered wave back towards the black hole. The wave may bounce back and forth between the black hole and some turning point amplifying itself each time. This may lead to a dynamical instability of the system, a phenomena known as a “black-hole bomb”. In this work we provide a bound on the instability regime of rotating Kerr spacetimes. In particular, we show that Kerr black holes are stable to massive perturbations in the regime μ⩾√(2)mΩ.

  15. Do Typical Galaxies in Adolescence Already Host Growing Black Holes?

    Science.gov (United States)

    Trump, Jonathan

    2012-10-01

    This archival grism proposal achieves a 100-fold gain in high-quality {5+sigma} information for discovering which properties of adolescent {0.7

  16. Thermodynamic and classical instability of AdS black holes in fourth-order gravity

    International Nuclear Information System (INIS)

    Myung, Yun Soo; Moon, Taeyoon

    2014-01-01

    We study thermodynamic and classical instability of AdS black holes in fourth-order gravity. These include the BTZ black hole in new massive gravity, Schwarzschild-AdS black hole, and higher-dimensional AdS black holes in fourth-order gravity. All thermodynamic quantities which are computed using the Abbot-Deser-Tekin method are used to study thermodynamic instability of AdS black holes. On the other hand, we investigate the s-mode Gregory-Laflamme instability of the massive graviton propagating around the AdS black holes. We establish the connection between the thermodynamic instability and the GL instability of AdS black holes in fourth-order gravity. This shows that the Gubser-Mitra conjecture holds for AdS black holes found from fourth-order gravity

  17. Massive neutral particles on heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Olivares, Marco [Pontificia Universidad de Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Villanueva, J.R. [Universidad de Valparaiso, Departamento de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile)

    2013-12-15

    The motion of massive particles in the background of a charged black hole in heterotic string theory, which is characterized by a parameter {alpha}, is studied in detail in this paper. Since it is possible to write this space-time in the Einstein frame, we perform a quantitative analysis of the time-like geodesics by means of the standard Lagrange procedure. Thus, we obtain and solve a set of differential equations and then we describe the orbits in terms of the elliptic p-Weierstrass function. Also, by making an elementary derivation developed by Cornbleet (Am. J. Phys. 61(7):650-651, 1993) we obtain the correction to the angle of advance of perihelion to first order in {alpha}, and thus, by comparing with Mercury's data we give an estimation for the value of this parameter, which yields an heterotic solar charge Q{sub s}un {approx_equal} 0.728 [Km]=0.493 M{sub s}un. Therefore, in addition to the study on null geodesics performed by Fernando (Phys. Rev. D 85:024033, 2012), this work completes the geodesic structure for this class of space-time. (orig.)

  18. Massively Parallel Dimension Independent Adaptive Metropolis

    KAUST Repository

    Chen, Yuxin

    2015-05-14

    This work considers black-box Bayesian inference over high-dimensional parameter spaces. The well-known and widely respected adaptive Metropolis (AM) algorithm is extended herein to asymptotically scale uniformly with respect to the underlying parameter dimension, by respecting the variance, for Gaussian targets. The result- ing algorithm, referred to as the dimension-independent adaptive Metropolis (DIAM) algorithm, also shows improved performance with respect to adaptive Metropolis on non-Gaussian targets. This algorithm is further improved, and the possibility of probing high-dimensional targets is enabled, via GPU-accelerated numerical libraries and periodically synchronized concurrent chains (justified a posteriori). Asymptoti- cally in dimension, this massively parallel dimension-independent adaptive Metropolis (MPDIAM) GPU implementation exhibits a factor of four improvement versus the CPU-based Intel MKL version alone, which is itself already a factor of three improve- ment versus the serial version. The scaling to multiple CPUs and GPUs exhibits a form of strong scaling in terms of the time necessary to reach a certain convergence criterion, through a combination of longer time per sample batch (weak scaling) and yet fewer necessary samples to convergence. This is illustrated by e ciently sampling from several Gaussian and non-Gaussian targets for dimension d 1000.

  19. MassiveNuS: cosmological massive neutrino simulations

    Science.gov (United States)

    Liu, Jia; Bird, Simeon; Zorrilla Matilla, José Manuel; Hill, J. Colin; Haiman, Zoltán; Madhavacheril, Mathew S.; Petri, Andrea; Spergel, David N.

    2018-03-01

    The non-zero mass of neutrinos suppresses the growth of cosmic structure on small scales. Since the level of suppression depends on the sum of the masses of the three active neutrino species, the evolution of large-scale structure is a promising tool to constrain the total mass of neutrinos and possibly shed light on the mass hierarchy. In this work, we investigate these effects via a large suite of N-body simulations that include massive neutrinos using an analytic linear-response approximation: the Cosmological Massive Neutrino Simulations (MassiveNuS). The simulations include the effects of radiation on the background expansion, as well as the clustering of neutrinos in response to the nonlinear dark matter evolution. We allow three cosmological parameters to vary: the neutrino mass sum Mν in the range of 0–0.6 eV, the total matter density Ωm, and the primordial power spectrum amplitude As. The rms density fluctuation in spheres of 8 comoving Mpc/h (σ8) is a derived parameter as a result. Our data products include N-body snapshots, halo catalogues, merger trees, ray-traced galaxy lensing convergence maps for four source redshift planes between zs=1–2.5, and ray-traced cosmic microwave background lensing convergence maps. We describe the simulation procedures and code validation in this paper. The data are publicly available at http://columbialensing.org.

  20. Low-mass black holes as the remnants of primordial black hole formation.

    Science.gov (United States)

    Greene, Jenny E

    2012-01-01

    Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.

  1. Are LIGO's Black Holes Made From Smaller Black Holes?

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    The recent successes of the Laser Interferometer Gravitational-Wave Observatory (LIGO) has raised hopes that several long-standing questions in black-hole physics will soon be answerable. Besides revealing how the black-hole binary pairs are built, could detections with LIGO also reveal how the black holes themselves form?Isolation or HierarchyThe first detection of gravitational waves, GW150914, was surprising for a number of reasons. One unexpected result was the mass of the two black holes that LIGO saw merging: they were a whopping 29 and 36 solar masses.On the left of this schematic, two first-generation (direct-collapse) black holes form a merging binary. The right illustrates a second-generation hierarchical merger: each black hole in the final merging binary was formed by the merger of two smaller black holes. [Adapted fromGerosa et al., a simultaneously published paper that also explores the problem of hierarchical mergers and reaches similar conclusions]How do black holes of this size form? One possibility is that they form in isolation from the collapse of a single massive star. In an alternative model, they are created through the hierarchical merger of smaller black holes, gradually building up to the size we observed.A team of scientists led by Maya Fishbach (University of Chicago) suggests that we may soon be able to tell whether or not black holes observed by LIGO formed hierarchically. Fishbach and collaborators argue that hierarchical formation leaves a distinctive signature on the spins of the final black holes and that as soon as we have enough merger detections from LIGO, we can use spin measurements to statistically determine if LIGO black holes were formed hierarchically.Spins from Major MergersWhen two black holes merge, both their original spins and the angular momentum of the pair contribute to the spin of the final black hole that results. Fishbach and collaborators calculate the expected distribution of these final spins assuming that

  2. Black Tea

    Science.gov (United States)

    ... leaves of the same plant, has some different properties. Black tea is used for improving mental alertness ... that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen ( ...

  3. Star formation around supermassive black holes.

    Science.gov (United States)

    Bonnell, I A; Rice, W K M

    2008-08-22

    The presence of young massive stars orbiting on eccentric rings within a few tenths of a parsec of the supermassive black hole in the galactic center is challenging for theories of star formation. The high tidal shear from the black hole should tear apart the molecular clouds that form stars elsewhere in the Galaxy, and transport of stars to the galactic center also appears unlikely during their lifetimes. We conducted numerical simulations of the infall of a giant molecular cloud that interacts with the black hole. The transfer of energy during closest approach allows part of the cloud to become bound to the black hole, forming an eccentric disk that quickly fragments to form stars. Compressional heating due to the black hole raises the temperature of the gas up to several hundred to several thousand kelvin, ensuring that the fragmentation produces relatively high stellar masses. These stars retain the eccentricity of the disk and, for a sufficiently massive initial cloud, produce an extremely top-heavy distribution of stellar masses. This potentially repetitive process may explain the presence of multiple eccentric rings of young stars in the presence of a supermassive black hole.

  4. A MASSIVE PROGENITOR OF THE LUMINOUS TYPE IIn SUPERNOVA 2010jl

    International Nuclear Information System (INIS)

    Smith, Nathan; Li Weidong; Miller, Adam A.; Silverman, Jeffrey M.; Filippenko, Alexei V.; Cuillandre, Jean-Charles; Cooper, Michael C.; Matheson, Thomas; Van Dyk, Schuyler D.

    2011-01-01

    The bright, nearby, recently discovered supernova (SN) 2010jl is a luminous Type IIn SN. Here, we report archival Hubble Space Telescope (HST) observations of its host galaxy UGC 5189A taken roughly 10 yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a luminous, blue point source at the position of the SN, with an absolute magnitude of -12.0 in the F300W filter. If it is not just a chance alignment, the source at the SN position could be (1) a massive young ( sun . This reinforces mounting evidence that many SNe IIn result from very massive stars, that massive stars can produce visible SNe without collapsing quietly to black holes, and that massive stars can sometimes retain their H envelopes until shortly before explosion. Standard stellar evolution models fail to account for these observed properties.

  5. Canonical structure of BHT massive gravity in warped AdS3 sector

    Directory of Open Access Journals (Sweden)

    Davood Mahdavian Yekta

    2016-08-01

    Full Text Available We investigate the asymptotic structure of the three dimensional Warped Anti-de Sitter (WAdS3 black holes in the Bergshoeff–Hohm–Townsend (BHT massive gravity using the canonical Hamiltonian formalism. We define the canonical asymptotic gauge generators, which produce the conserved charges and the asymptotic symmetry group for the WAdS3 black holes. The attained symmetry group is described by a semi-direct sum of a Virasoro and a Kač–Moody algebra. Using the Sugawara construction, we obtain a direct sum of two Virasoro algebras. We show that not only the asymptotic conserved charges satisfy the first law of black hole thermodynamics, but also they lead to the expected Smarr formula for the WAdS3 black holes. We also show that the black hole's entropy obeys the Cardy formula of the dual conformal field theory (CFT.

  6. Efficient optimal joint channel estimation and data detection for massive MIMO systems

    KAUST Repository

    Alshamary, Haider Ali Jasim

    2016-08-15

    In this paper, we propose an efficient optimal joint channel estimation and data detection algorithm for massive MIMO wireless systems. Our algorithm is optimal in terms of the generalized likelihood ratio test (GLRT). For massive MIMO systems, we show that the expected complexity of our algorithm grows polynomially in the channel coherence time. Simulation results demonstrate significant performance gains of our algorithm compared with suboptimal non-coherent detection algorithms. To the best of our knowledge, this is the first algorithm which efficiently achieves GLRT-optimal non-coherent detections for massive MIMO systems with general constellations.

  7. Growing up with Retinoblastoma

    Science.gov (United States)

    Maley, Tom

    2005-01-01

    An account is given of growing up as a child blinded as a result of a cancer of the eye known as retinoblastoma. The role of his mother is brought out, variously as a source of objective knowledge, of one's personal worth, and of the worth of other people in one's community. The strengths and weaknesses of his first school in his home area and…

  8. The Supermassive Black Hole—Galaxy Connection

    Science.gov (United States)

    King, Andrew

    2014-09-01

    The observed scaling relations imply that supermassive black holes (SMBH) and their host galaxies evolve together. Near-Eddington winds from the SMBH accretion discs explain many aspects of this connection. The wind Eddington factor should be in the range ˜1-30. A factor give black hole winds with velocities v˜0.1 c, observable in X-rays, just as seen in the most extreme ultrafast outflows (UFOs). Higher Eddington factors predict slower and less ionized winds, observable in the UV, as in BAL QSOs. In all cases the wind must shock against the host interstellar gas and it is plausible that these shocks should cool efficiently. There is detailed observational evidence for this in some UFOs. The wind sweeps up the interstellar gas into a thin shell and propels it outwards. For SMBH masses below a certain critical ( M- σ) value, all these outflows eventually stall and fall back, as the Eddington thrust of the wind is too weak to drive the gas to large radii. But once the SMBH mass reaches the critical M- σ value the global character of the outflow changes completely. The wind shock is no longer efficiently cooled, and the resulting thermal expansion drives the interstellar gas far from the black hole, which is unlikely to grow significantly further. Simple estimates of the maximum stellar bulge mass M b allowed by self-limited star formation show that the SMBH mass is typically about 10-3 M b at this point, in line with observation. The expansion-driven outflow reaches speeds v out≃1200 km s-1 and drives rates in cool (molecular) gas, giving a typical outflow mechanical energy L mech≃0.05 L Edd, where L Edd is the Eddington luminosity of the central SMBH. This is again in line with observation. These massive outflows may be what makes galaxies become red and dead, and can have several other potentially observable effects. In particular they have the right properties to enrich the intergalactic gas with metals. Our current picture of SMBH-galaxy coevolution is

  9. Cleaning Massive Sonar Point Clouds

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Larsen, Kasper Green; Mølhave, Thomas

    2010-01-01

    We consider the problem of automatically cleaning massive sonar data point clouds, that is, the problem of automatically removing noisy points that for example appear as a result of scans of (shoals of) fish, multiple reflections, scanner self-reflections, refraction in gas bubbles, and so on. We...... describe a new algorithm that avoids the problems of previous local-neighbourhood based algorithms. Our algorithm is theoretically I/O-efficient, that is, it is capable of efficiently processing massive sonar point clouds that do not fit in internal memory but must reside on disk. The algorithm is also...... relatively simple and thus practically efficient, partly due to the development of a new simple algorithm for computing the connected components of a graph embedded in the plane. A version of our cleaning algorithm has already been incorporated in a commercial product....

  10. Winds of Change: How Black Holes May Shape Galaxies

    Science.gov (United States)

    2010-03-01

    New observations from NASA's Chandra X-ray Observatory provide evidence for powerful winds blowing away from the vicinity of a supermassive black hole in a nearby galaxy. This discovery indicates that "average" supermassive black holes may play an important role in the evolution of the galaxies in which they reside. For years, astronomers have known that a supermassive black hole grows in parallel with its host galaxy. And, it has long been suspected that material blown away from a black hole - as opposed to the fraction of material that falls into it -- alters the evolution of its host galaxy. A key question is whether such "black hole blowback" typically delivers enough power to have a significant impact. Powerful relativistic jets shot away from the biggest supermassive black holes in large, central galaxies in clusters like Perseus are seen to shape their host galaxies, but these are rare. What about less powerful, less focused galaxy-scale winds that should be much more common? "We're more interested here in seeing what an "average"-sized supermassive black hole can do to its galaxy, not the few, really big ones in the biggest galaxies," said Dan Evans of the Massachusetts Institute of Technology who presented these results at the High Energy Astrophysics Division of the American Astronomical Society meeting in Kona, Hawaii. Evans and his colleagues used Chandra for five days to observe NGC 1068, one of the nearest and brightest galaxies containing a rapidly growing supermassive black hole. This black hole is only about twice as massive as the one in the center of our Galaxy, which is considered to be a rather ordinary size. The X-ray images and spectra obtained using Chandra's High Energy Transmission Grating Spectrometer (HETGS) showed that a strong wind is being driven away from the center of NGC 1068 at a rate of about a million miles per hour. This wind is likely generated as surrounding gas is accelerated and heated as it swirls toward the black hole. A

  11. Massive gravity on a brane

    Energy Technology Data Exchange (ETDEWEB)

    Chacko, Z.; Graesser, M.L.; Grojean, C.; Pilo, L.

    2003-12-11

    At present no theory of a massive graviton is known that is consistent with experiments at both long and short distances. The problem is that consistency with long distance experiments requires the graviton mass to be very small. Such a small graviton mass however implies an ultraviolet cutoff for the theory at length scales far larger than the millimeter scale at which gravity has already been measured. In this paper we attempt to construct a model which avoids this problem. We consider a brane world setup in warped AdS spacetime and we investigate the consequences of writing a mass term for the graviton on a the infrared brane where the local cutoff is of order a large (galactic) distance scale. The advantage of this setup is that the low cutoff for physics on the infrared brane does not significantly affect the predictivity of the theory for observers localized on the ultraviolet brane. For such observers the predictions of this theory agree with general relativity at distances smaller than the infrared scale but go over to those of a theory of massive gravity at longer distances. A careful analysis of the graviton two-point function, however, reveals the presence of a ghost in the low energy spectrum. A mode decomposition of the higher dimensional theory reveals that the ghost corresponds to the radion field. We also investigate the theory with a brane localized mass for the graviton on the ultraviolet brane, and show that the physics of this case is similar to that of a conventional four dimensional theory with a massive graviton, but with one important difference: when the infrared brane decouples and the would-be massive graviton gets heavier than the regular Kaluza-Klein modes, it becomes unstable and it has a finite width to decay off the brane into the continuum of Kaluza-Klein states.

  12. Understanding massively open online courses.

    Science.gov (United States)

    Billings, Diane M

    2014-02-01

    Massively open online courses (MOOCs) are an innovative delivery system for educational offerings. MOOCs have been hailed with optimism for making education accessible to many, but at the same time, they have been criticized for poor participant completion rates. Nurse educators are considering whether and how to use MOOCs; this column explains MOOCs and their advantages and disadvantages for nurse educators. Copyright 2014, SLACK Incorporated.

  13. Massive branes and creation of branes

    NARCIS (Netherlands)

    Bergshoeff, E; Dorn, H; Lust, D; Weigt, G

    1998-01-01

    We investigate the effective worldvolume theories of p-branes and D-branes in a massive background given by (the bosonic sector of) 10-dimensional massive IIA supergravity ("massive branes"). As an application we discuss the consequences of our results for the anomalous creation of branes.

  14. Super-Eddington Growth Of The First Black Holes

    Science.gov (United States)

    Pezzulli, Edwige; Valiante, R.; Schneider, R.

    2016-10-01

    The formation and growth of the first super massive black holes (SMBHs) at z 6 is a subject of intense debate. If black holes grow at their Eddington rates, they must start from high-mass seeds, (Mseed 10^4 -10^5 Msun), formed by direct collapse of gasHere I will consider an alternative scenario where remnant of population III stars, (M 100 Msun), can grow at super-Eddington rates via radiatively inefficient slim accretion disks. In Pezzulli et al., (MNRAS 2016), we use an improved version of the cosmological, data-constrained semi-analytic model GAMETE/QSODUST. We follow, for each progenitor present in the simulation, the evolution of nuclear BH, gas cooling, disk and bulge formation of their host galaxies together with the star formation, SNe/AGN feedback and chemical and dust enrichment. By adopting SDSS J1148+5251 at z=6.4 as a prototype of luminous z=6 quasars, we find that 80% of the SMBH mass of J1148 is provided by super-Eddington gas accretion, which can be sustained down to z 10 in dense, gas-rich environments, and the BH progenitors of the final SMBH evolve in symbiosis with their host galaxiesWe reproduce all the observed quantities of J1148, also predicting an AGN-driven mass outflow rate at z=6.4 broadly consistent with the radial profile inferred from CII observation by Cicone et al. 2015. Interestingly, find that 20% of J1148 progenitors at z=7.1 have BH luminosities and masses comparable to ULAS J1120, suggesting that the most distant quasar ever observed may be one of the progenitors of J1148.

  15. Formation of a black hole in the dark.

    Science.gov (United States)

    Mirabel, I Félix; Rodrigues, Irapuan

    2003-05-16

    We show that the black hole in the x-ray binary Cygnus X-1 was formed in situ and did not receive an energetic trigger from a nearby supernova. The progenitor of the black hole had an initial mass greater than 40 solar masses, and during the collapse to form the approximately 10-solar mass black hole of Cygnus X-1, the upper limit for the mass that could have been suddenly ejected is approximately 1 solar mass, much less than the mass ejected in a supernova. The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently.

  16. Black Holes from the Dark Ages:. Exploring the Reionization ERA and Early Structure Formation with Quasars and Gamma-Ray Bursts

    Science.gov (United States)

    Djorgovski, S. G.

    2006-02-01

    The cosmic reionization era, which includes formation of the first stars, galaxies, and AGN, is now one of the most active frontiers of cosmological research. We review briefly our current understanding of the early structure formation, and use the ideas about a joint formation of massive black holes (which power the early QSOs) and their host galaxies to employ high-redshift QSOs as probes of the early galaxy formation and primordial large-scale structure. There is a growing evidence for a strong biasing in the formation of the first luminous sources, which would lead to a clumpy reionization. Absorption spectroscopy of QSOs at z ≥ 6 indicates the end of the reionization era at z 6; yet measurements from the WMAP satellite suggest and early reionization at z 10 - 20. The first generation of massive stars, perhaps aided by the early mini-quasars, may have reionized the universe at such high redshifts, but their feedback may have disrupted the subsequent star and galaxy formation, leading to an extended and perhaps multimodal reionization history ending by z 6. Observations of γ-ray bursts from the death events of these putative Population III stars may provide essential insight into the primordial structure formation, reionization, early chemical enrichment, and formation of seed black holes which may grow to become central engines of luminous quasars.

  17. Measuring the spins of accreting black holes

    International Nuclear Information System (INIS)

    McClintock, Jeffrey E; Narayan, Ramesh; Gou, Lijun; Kulkarni, Akshay; Penna, Robert F; Steiner, James F; Davis, Shane W; Orosz, Jerome A; Remillard, Ronald A

    2011-01-01

    A typical galaxy is thought to contain tens of millions of stellar-mass black holes, the collapsed remnants of once massive stars, and a single nuclear supermassive black hole. Both classes of black holes accrete gas from their environments. The accreting gas forms a flattened orbiting structure known as an accretion disk. During the past several years, it has become possible to obtain measurements of the spins of the two classes of black holes by modeling the x-ray emission from their accretion disks. Two methods are employed, both of which depend upon identifying the inner radius of the accretion disk with the innermost stable circular orbit, whose radius depends only on the mass and spin of the black hole. In the Fe Kα method, which applies to both classes of black holes, one models the profile of the relativistically broadened iron line with a special focus on the gravitationally redshifted red wing of the line. In the continuum-fitting (CF) method, which has so far only been applied to stellar-mass black holes, one models the thermal x-ray continuum spectrum of the accretion disk. We discuss both methods, with a strong emphasis on the CF method and its application to stellar-mass black holes. Spin results for eight stellar-mass black holes are summarized. These data are used to argue that the high spins of at least some of these black holes are natal, and that the presence or absence of relativistic jets in accreting black holes is not entirely determined by the spin of the black hole.

  18. Collapse of primordial gas clouds and the formation of quasar black holes

    Science.gov (United States)

    Loeb, Abraham; Rasio, Frederic A.

    1994-01-01

    The formation of quasar black holes during the hydrodynamic collapse of protogalactic gas clouds is discussed. The dissipational collapse and long-term dynamical evolution of these systems is analyzed using three-dimensional numerical simulations. The calculations focus on the final collapse stages of the inner baryonic component and therefore ignore the presence of dark matter. Two types of initial conditions are considered: uniformly rotating spherical clouds, and iirotational ellipsoidal clouds. In both cases the clouds are initially cold, homogeneous, and not far from rotational support (T/(absolute value of W) approximately equals 0.1). Although the details of the dynamical evolution depend sensitively on the initial conditions, the qualitative features of the final configurations do not. Most of the gas is found to fragment into small dense clumps, that eventually make up a spheroidal component resembling a galactic bulge. About 5% of the initial mass remains in the form of a smooth disk of gas supported by rotation in the gravitational potential potential well of the outer spheroid. If a central seed black hole of mass approximately greater than 10(exp 6) solar mass forms, it can grow by steady accretion from the disk and reach a typical quasar black hole mass approximately 10(exp 8) solar mass in less than 5 x 10(exp 8) yr. In the absence of a sufficiently massive seed, dynamical instabilities in a strongly self-gravitating inner region of the disk will inhibit steady accretion of gas and may prevent the immediate formation of quasar.

  19. Vaidya spacetime in massive gravity's rainbow

    Science.gov (United States)

    Heydarzade, Yaghoub; Rudra, Prabir; Darabi, Farhad; Ali, Ahmed Farag; Faizal, Mir

    2017-11-01

    In this paper, we will analyze the energy dependent deformation of massive gravity using the formalism of massive gravity's rainbow. So, we will use the Vainshtein mechanism and the dRGT mechanism for the energy dependent massive gravity, and thus analyze a ghost free theory of massive gravity's rainbow. We study the energy dependence of a time-dependent geometry, by analyzing the radiating Vaidya solution in this theory of massive gravity's rainbow. The energy dependent deformation of this Vaidya metric will be performed using suitable rainbow functions.

  20. Vaidya spacetime in massive gravity's rainbow

    Directory of Open Access Journals (Sweden)

    Yaghoub Heydarzade

    2017-11-01

    Full Text Available In this paper, we will analyze the energy dependent deformation of massive gravity using the formalism of massive gravity's rainbow. So, we will use the Vainshtein mechanism and the dRGT mechanism for the energy dependent massive gravity, and thus analyze a ghost free theory of massive gravity's rainbow. We study the energy dependence of a time-dependent geometry, by analyzing the radiating Vaidya solution in this theory of massive gravity's rainbow. The energy dependent deformation of this Vaidya metric will be performed using suitable rainbow functions.

  1. Image segmentation by iterative parallel region growing and splitting

    Science.gov (United States)

    Tilton, James C.

    1989-01-01

    The spatially constrained clustering (SCC) iterative parallel region-growing technique is applied to image analysis. The SCC algorithm is implemented on the massively parallel processor at NASA Goddard. Most previous region-growing approaches have the drawback that the segmentation produced depends on the order in which portions of the image are processed. The ideal solution to this problem (merging only the single most similar pair of spatially adjacent regions in the image in each iteration) becomes impractical except for very small images, even on a massively parallel computer. The SCC algorithm overcomes these problems by performing, in parallel, the best merge within each of a set of local, possibly overlapping, subimages. A region-splitting stage is also incorporated into the algorithm, but experiments show that region splitting generally does not improve segmentation results. The SCC algorithm has been tested on various imagery data, and test results for a Landsat TM image are summarized.

  2. STABLE ISOTOPE GEOCHEMISTRY OF MASSIVE ICE

    Directory of Open Access Journals (Sweden)

    Yurij K. Vasil’chuk

    2016-01-01

    Full Text Available The paper summarises stable-isotope research on massive ice in the Russian and North American Arctic, and includes the latest understanding of massive-ice formation. A new classification of massive-ice complexes is proposed, encompassing the range and variabilityof massive ice. It distinguishes two new categories of massive-ice complexes: homogeneousmassive-ice complexes have a similar structure, properties and genesis throughout, whereasheterogeneous massive-ice complexes vary spatially (in their structure and properties andgenetically within a locality and consist of two or more homogeneous massive-ice bodies.Analysis of pollen and spores in massive ice from Subarctic regions and from ice and snow cover of Arctic ice caps assists with interpretation of the origin of massive ice. Radiocarbon ages of massive ice and host sediments are considered together with isotope values of heavy oxygen and deuterium from massive ice plotted at a uniform scale in order to assist interpretation and correlation of the ice.

  3. Two new confirmed massive relic galaxies: red nuggets in the present-day Universe

    Science.gov (United States)

    Ferré-Mateu, Anna; Trujillo, Ignacio; Martín-Navarro, Ignacio; Vazdekis, Alexandre; Mezcua, Mar; Balcells, Marc; Domínguez, Lilian

    2017-05-01

    We confirm two new local massive relic galaxies, I.e. untouched survivors of the early Universe massive population: Mrk 1216 and PGC 032873. Both show early and peaked formation events within very short time-scales (histories remain virtually unchanged out to several effective radii, even when considering the steeper initial-mass-function values inferred out to ˜3 effective radii. Their morphologies, kinematics and density profiles are like those found in the z > 2 massive population, setting them apart from the typical z ˜ 0 massive early-type galaxies. We find that there seems to exist a degree of relic that is related to how far into the path, to become one of these typical z ˜ 0 massive galaxies, the compact relic has moved. This path is partly dictated by the environment the galaxy lives in. For galaxies in rich environments, such as the previously reported relic galaxy NGC 1277, the most extreme properties (e.g. sizes, short formation time-scales, larger supermassive black holes) are expected, while lower density environments will have galaxies with delayed and/or extended star formations, slightly larger sizes and not that extreme black hole masses. The confirmation of three relic galaxies up to a distance of 106 Mpc, implies a lower limit in the number density of these red nuggets in the local Universe of 6 × 10-7 Mpc3, which is within the theoretical expectations.

  4. Spacetime structure of massive Majorana particles and massive gravitino

    CERN Document Server

    Ahluwalia, D V

    2003-01-01

    The profound difference between Dirac and Majorana particles is traced back to the possibility of having physically different constructs in the (1/2, 0) 0 (0,1/2) representation space. Contrary to Dirac particles, Majorana-particle propagators are shown to differ from the simple linear gamma mu p submu, structure. Furthermore, neither Majorana particles, nor their antiparticles can be associated with a well defined arrow of time. The inevitable consequence of this peculiarity is the particle-antiparticle metamorphosis giving rise to neutrinoless double beta decay, on the one side, and enabling spin-1/2 fields to act as gauge fields, gauginos, on the other side. The second part of the lecture notes is devoted to massive gravitino. We argue that a spin measurement in the rest frame for an unpolarized ensemble of massive gravitino, associated with the spinor-vector [(1/2, 0) 0 (0,1/2)] 0 (1/2,1/2) representation space, would yield the results 3/2 with probability one half, and 1/2 with probability one half. The ...

  5. Body image concerns amongst massive weight loss patients.

    Science.gov (United States)

    Gilmartin, Jo

    2013-05-01

    To explore body image matters amongst patients following massive weight loss. In contemporary health care, a growing number of morbidly obese patients are seeking surgical solutions such as bariatric surgery or in other cases engaging with radical lifestyle changes. Massive weight loss can leave patients with a huge excess of lax overstretched skin that in some cases can trigger major body image dissatisfaction or depression. There is a scarcity of research about the needs of this group of patients and this is important for nursing practice. A qualitative design using in-depth interviews was employed. Twenty white adults (18 women and two men) were recruited retrospectively amongst patients who had massive weight loss by undergoing bariatric surgery or radical lifestyle changes, aged 29-63 years. All of the participants gave signed informed consent. Face-to-face in-depth interviews were conducted and transcribed verbatim. The data were analysed using thematic analysis. One core theme focusing on body image ugliness and three associated subthemes were identified: the subthemes included feeling socially marginalised, feeling depressed and sexual and intimacy difficulties. Body image matters are hugely significant and appear to have a lasting effect on emotional well-being and function, contributing to psychological distress and social isolation. Greater sensitivity is required in enabling patients to work through emotional isolation and shame that has been a part of their childhood. Furthermore more, treatments need to be accessible to this growing patient population such as reconstructive surgery. Nurses who care for massive weight loss patients need to be mindful of their psychodynamic needs and be non-judgemental and accepting. Moreover, nurses need to be aware of treatment options and be able to assess body image matters and implement quality care for this particular patient group including body image acceptance programmes and support groups. © 2013 Blackwell

  6. All or nothing: On the small fluctuations of two-dimensional string theoretic black holes

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Gerald [Univ. of Maryland, College Park, MD (United States); Raiten, Eric [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    1992-10-01

    A comprehensive analysis of small fluctuations about two-dimensional string-theoretic and string-inspired black holes is presented. It is shown with specific examples that two-dimensional black holes behave in a radically different way from all known black holes in four dimensions. For both the SL(2,R)/U(1) black hole and the two-dimensional black hole coupled to a massive dilaton with constant field strength, it is shown that there are a {\\it continuous infinity} of solutions to the linearized equations of motion, which are such that it is impossible to ascertain the classical linear response. It is further shown that the two-dimensional black hole coupled to a massive, linear dilaton admits {\\it no small fluctuations at all}. We discuss possible implications of our results for the Callan-Giddings-Harvey-Strominger black hole.

  7. The evolution of massive stars

    International Nuclear Information System (INIS)

    Loore, C. de

    1980-01-01

    The evolution of stars with masses between 15 M 0 and 100 M 0 is considered. Stars in this mass range lose a considerable fraction of their matter during their evolution. The treatment of convection, semi-convection and the influence of mass loss by stellar winds at different evolutionary phases are analysed as well as the adopted opacities. Evolutionary sequences computed by various groups are examined and compared with observations, and the advanced evolution of a 15 M 0 and a 25 M 0 star from zero-age main sequence (ZAMS) through iron collapse is discussed. The effect of centrifugal forces on stellar wind mass loss and the influence of rotation on evolutionary models is examined. As a consequence of the outflow of matter deeper layers show up and when the mass loss rates are large enough layers with changed composition, due to interior nuclear reactions, appear on the surface. The evolution of massive close binaries as well during the phase of mass loss by stellar wind as during the mass exchange and mass loss phase due to Roche lobe overflow is treated in detail, and the value of the parameters governing mass and angular momentum losses are discussed. The problem of the Wolf-Rayet stars, their origin and the possibilities of their production either as single stars or as massive binaries is examined. Finally, the origin of X-ray binaries is discussed and the scenario for the formation of these objects (starting from massive ZAMS close binaries, through Wolf-Rayet binaries leading to OB-stars with a compact companion after a supernova explosion) is reviewed and completed, including stellar wind mass loss. (orig.)

  8. Massive stars, successes and challenges

    Science.gov (United States)

    Meynet, Georges; Maeder, André; Georgy, Cyril; Ekström, Sylvia; Eggenberger, Patrick; Barblan, Fabio; Song, Han Feng

    2017-11-01

    We give a brief overview of where we stand with respect to some old and new questions bearing on how massive stars evolve and end their lifetime. We focus on the following key points that are further discussed by other contributions during this conference: convection, mass losses, rotation, magnetic field and multiplicity. For purpose of clarity, each of these processes are discussed on its own but we have to keep in mind that they are all interacting between them offering a large variety of outputs, some of them still to be discovered.

  9. Growing Data User Communities

    Science.gov (United States)

    Wiggin, B.

    2017-12-01

    Preserving data is not only a technical challenge. Perhaps the best way to protect data is to use it. Grassroots efforts to make research-quality copies of federal data continue to energize communities of data users who often did not previously recognize themselves as open earth data users. Beyond "data rescue" events, the Data Refuge project researches how federal climate and environmental data are used downstream in a variety of local communities and municipal governments to address everyday issues: public health, municipal safety, and even the preservation of cultural heritage assets. Documenting the diverse uses made of open earth data beyond the earth sciences research community grows the community who, in making use of data, also helps to preserve it.

  10. Growing Old in Exile

    DEFF Research Database (Denmark)

    Liversage, Anika; Mirdal, Gretty Mizrahi

    2017-01-01

    Some studies on immigrants and ageing focus on the question of return; others focus on how immigrants, who grow old in their countries of destination, ‘age in place’, including whether they turn to their children or to public host country provisions for care and support. However, the issues...... of return and of ageing in place may both hold significance in individual immigrants’ lives. To investigate the changing expectations of old age throughout the life course, this paper draws on longitudinal interviews with immigrant women from Turkey who live in Denmark. We focus on the function of proximity...... to children. Using two women who were interviewed three times over three decades as case studies, the analysis shows that in the middle of life, the women share expectations of returning to Turkey, but these plans are perpetually postponed. As the women age, they must face their inability to leave...

  11. The growing fibroadenoma

    International Nuclear Information System (INIS)

    Sanders, Linda M; Sara, Rana

    2015-01-01

    Fibroadenomas (FAs) are the most common tumors of the breast clinically and pathologically in adolescent and young women but may be discovered at any age. With increasing use of core biopsy rather than excision for diagnosis, it is now commonplace to follow these lesions with imaging. To assess the incidence of epithelial abnormalities (atypia, in situ or invasive, ductal or lobular malignancies) in FAs diagnosed by core biopsy and to re-evaluate the management paradigm for any growing FA. A retrospective review of the senior author’s pathology results over 19 years identified 2062 nodular FAs (biopsied by ultrasound or stereotactic guidance). Eighty-three core biopsied FAs were identified which subsequently enlarged. Twelve of 2062 of core biopsied nodules demonstrated atypia, in situ, or invasive malignancy (ductal or lobular) within or adjacent to the FA (0.58%). Eighty-three FAs enlarged and underwent either surgical excision (n = 65), repeat core biopsy (n = 9), or imaging follow-up (n = 9). The incidence of atypia, in situ or invasive malignancy was 0/83 (0%). Two enlarging FAs were subsequently surgically diagnosed as benign phyllodes tumors (PT). Malignancy in or adjacent to a core biopsied FA is rare. The risk of cancer in a growing FA is even rarer; none were present in our series. FAs with abnormal epithelial abnormalities require excision. Otherwise, FAs without epithelial abnormality diagnosed by core biopsy need no specific follow-up considering the negligible incidence of conversion to malignancy. The breast interventionalist must know how to manage discordant pathology results

  12. Black-hole bomb and superradiant instabilities

    International Nuclear Information System (INIS)

    Cardoso, Vitor; Dias, Oscar J.C.; Lemos, Jose P.S.; Yoshida, Shijun

    2004-01-01

    A wave impinging on a Kerr black hole can be amplified as it scatters off the hole if certain conditions are satisfied, giving rise to superradiant scattering. By placing a mirror around the black hole one can make the system unstable. This is the black-hole bomb of Press and Teukolsky. We investigate in detail this process and compute the growing time scales and oscillation frequencies as a function of the mirror's location. It is found that in order for the system black hole plus mirror to become unstable there is a minimum distance at which the mirror must be located. We also give an explicit example showing that such a bomb can be built. In addition, our arguments enable us to justify why large Kerr-AdS black holes are stable and small Kerr-AdS black holes should be unstable

  13. Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies.

    Science.gov (United States)

    McConnell, Nicholas J; Ma, Chung-Pei; Gebhardt, Karl; Wright, Shelley A; Murphy, Jeremy D; Lauer, Tod R; Graham, James R; Richstone, Douglas O

    2011-12-08

    Observational work conducted over the past few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some were powered by black holes with masses greater than 10 billion solar masses, the remnants of these objects have not been found in the nearby Universe. The giant elliptical galaxy Messier 87 hosts the hitherto most massive known black hole, which has a mass of 6.3 billion solar masses. Here we report that NGC 3842, the brightest galaxy in a cluster at a distance from Earth of 98 megaparsecs, has a central black hole with a mass of 9.7 billion solar masses, and that a black hole of comparable or greater mass is present in NGC 4889, the brightest galaxy in the Coma cluster (at a distance of 103 megaparsecs). These two black holes are significantly more massive than predicted by linearly extrapolating the widely used correlations between black-hole mass and the stellar velocity dispersion or bulge luminosity of the host galaxy. Although these correlations remain useful for predicting black-hole masses in less massive elliptical galaxies, our measurements suggest that different evolutionary processes influence the growth of the largest galaxies and their black holes.

  14. Spacetime and orbits of bumpy black holes

    International Nuclear Information System (INIS)

    Vigeland, Sarah J.; Hughes, Scott A.

    2010-01-01

    Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced ''bumpy black holes'': objects that are almost, but not quite, general relativity's black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation is zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes--objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime's bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track the orbital phase of a small orbiting body. We find that in the weak field, orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is many times greater than would be predicted from a Newtonian analysis, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime's multipoles deviate from the black hole expectation.

  15. Quantum corrections to Schwarzschild black hole

    Energy Technology Data Exchange (ETDEWEB)

    Calmet, Xavier; El-Menoufi, Basem Kamal [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-04-15

    Using effective field theory techniques, we compute quantum corrections to spherically symmetric solutions of Einstein's gravity and focus in particular on the Schwarzschild black hole. Quantum modifications are covariantly encoded in a non-local effective action. We work to quadratic order in curvatures simultaneously taking local and non-local corrections into account. Looking for solutions perturbatively close to that of classical general relativity, we find that an eternal Schwarzschild black hole remains a solution and receives no quantum corrections up to this order in the curvature expansion. In contrast, the field of a massive star receives corrections which are fully determined by the effective field theory. (orig.)

  16. Black Willow

    Science.gov (United States)

    R. M. Krinard

    1980-01-01

    Black willow and other species of Salix together comprise a majority of the stocking. Cottonwood is the chief associate, particularly in the early stages, but green ash, sycamore, pecan, persimmon, waterlocust, American elm, baldcypress, red maple, sugarberry, box-elder, and in some areas, silver maple are invaders preceding the next successional stage.

  17. Counseling Blacks

    Science.gov (United States)

    Vontress, Clemmont E.

    1970-01-01

    Blacks have developed unique environmental perceptions, values, and attitudes, making it difficult for counselors to establish and maintain positive rapport. This article examines attitudinal ingredients posited by Carl Rogers for relevance to this problem, and suggests in-service training to help counselors and other professionals relate…

  18. Black Psyllium

    Science.gov (United States)

    ... by mouth for up to 6 weeks reduces blood sugar in people with type 2 diabetes. Cancer. Diarrhea. Irritable bowel syndrome (IBS). Other conditions. ... with the dose. Diabetes: Black psyllium can lower blood sugar levels ... with type 2 diabetes by slowing down absorption of carbohydrates. Monitor blood ...

  19. Black hole astrophysics

    International Nuclear Information System (INIS)

    Blandford, R.D.; Thorne, K.S.

    1979-01-01

    Following an introductory section, the subject is discussed under the headings: on the character of research in black hole astrophysics; isolated holes produced by collapse of normal stars; black holes in binary systems; black holes in globular clusters; black holes in quasars and active galactic nuclei; primordial black holes; concluding remarks on the present state of research in black hole astrophysics. (U.K.)

  20. Quantum black holes

    CERN Document Server

    Calmet, Xavier; Winstanley, Elizabeth

    2014-01-01

    Written by foremost experts, this short book gives a clear description of the physics of quantum black holes. The reader will learn about quantum black holes in four and higher dimensions, primordial black holes, the production of black holes in high energy particle collisions, Hawking radiation, black holes in models of low scale quantum gravity and quantum gravitational aspects of black holes.

  1. Teleporting entanglement during black hole evaporation

    International Nuclear Information System (INIS)

    Brustein, Ram; Medved, A.J.M.

    2016-01-01

    The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH’s life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.

  2. Teleporting entanglement during black hole evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Brustein, Ram [Department of Physics, Ben-Gurion University,Beer-Sheva 84105 (Israel); Medved, A.J.M. [Department of Physics & Electronics, Rhodes University,Grahamstown 6140 (South Africa); National Institute for Theoretical Physics (NITheP),Western Cape 7602 (South Africa)

    2016-10-06

    The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH’s life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.

  3. Surprise: Dwarf Galaxy Harbors Supermassive Black Hole

    Science.gov (United States)

    2011-01-01

    The surprising discovery of a supermassive black hole in a small nearby galaxy has given astronomers a tantalizing look at how black holes and galaxies may have grown in the early history of the Universe. Finding a black hole a million times more massive than the Sun in a star-forming dwarf galaxy is a strong indication that supermassive black holes formed before the buildup of galaxies, the astronomers said. The galaxy, called Henize 2-10, 30 million light-years from Earth, has been studied for years, and is forming stars very rapidly. Irregularly shaped and about 3,000 light-years across (compared to 100,000 for our own Milky Way), it resembles what scientists think were some of the first galaxies to form in the early Universe. "This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before," said Amy Reines, a Ph.D. candidate at the University of Virginia. Supermassive black holes lie at the cores of all "full-sized" galaxies. In the nearby Universe, there is a direct relationship -- a constant ratio -- between the masses of the black holes and that of the central "bulges" of the galaxies, leading them to conclude that the black holes and bulges affected each others' growth. Two years ago, an international team of astronomers found that black holes in young galaxies in the early Universe were more massive than this ratio would indicate. This, they said, was strong evidence that black holes developed before their surrounding galaxies. "Now, we have found a dwarf galaxy with no bulge at all, yet it has a supermassive black hole. This greatly strengthens the case for the black holes developing first, before the galaxy's bulge is formed," Reines said. Reines, along with Gregory Sivakoff and Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO), and Crystal Brogan of the NRAO, observed Henize 2-10 with the National Science Foundation's Very Large Array radio telescope and

  4. Microlensing Signature of Binary Black Holes

    Science.gov (United States)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  5. Melting ice, growing trade?

    Directory of Open Access Journals (Sweden)

    Sami Bensassi

    2016-05-01

    Full Text Available Abstract Large reductions in Arctic sea ice, most notably in summer, coupled with growing interest in Arctic shipping and resource exploitation have renewed interest in the economic potential of the Northern Sea Route (NSR. Two key constraints on the future viability of the NSR pertain to bathymetry and the future evolution of the sea ice cover. Climate model projections of future sea ice conditions throughout the rest of the century suggest that even under the most “aggressive” emission scenario, increases in international trade between Europe and Asia will be very low. The large inter-annual variability of weather and sea ice conditions in the route, the Russian toll imposed for transiting the NSR, together with high insurance costs and scarce loading/unloading opportunities, limit the use of the NSR. We show that even if these obstacles are removed, the duration of the opening of the NSR over the course of the century is not long enough to offer a consequent boost to international trade at the macroeconomic level.

  6. Massive Open Online Courses: what will be their legacy?

    Science.gov (United States)

    Daniel, John

    2016-04-01

    Massive Open Online Courses (MOOCs) dominated discussions of online learning and higher education in the news media and in universities between 2012 and 2015. However, fashions pass, needs change and technology evolves. This Commentary looks back, pauses on the present, and then looks forward. Whilst MOOCs are a significant milestone on the road that online teaching and learning is following, open, distance and online learning started long before MOOCs and will continue to grow in importance when MOOCs are just an interesting footnote in its development. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Thermal BEC Black Holes

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2015-10-01

    Full Text Available We review some features of Bose–Einstein condensate (BEC models of black holes obtained by means of the horizon wave function formalism. We consider the Klein–Gordon equation for a toy graviton field coupled to a static matter current in a spherically-symmetric setup. The classical field reproduces the Newtonian potential generated by the matter source, while the corresponding quantum state is given by a coherent superposition of scalar modes with a continuous occupation number. An attractive self-interaction is needed for bound states to form, the case in which one finds that (approximately one mode is allowed, and the system of N bosons can be self-confined in a volume of the size of the Schwarzschild radius. The horizon wave function formalism is then used to show that the radius of such a system corresponds to a proper horizon. The uncertainty in the size of the horizon is related to the typical energy of Hawking modes: it decreases with the increasing of the black hole mass (larger number of gravitons, resulting in agreement with the semiclassical calculations and which does not hold for a single very massive particle. The spectrum of these systems has two components: a discrete ground state of energy m (the bosons forming the black hole and a continuous spectrum with energy ω > m (representing the Hawking radiation and modeled with a Planckian distribution at the expected Hawking temperature. Assuming the main effect of the internal scatterings is the Hawking radiation, the N-particle state can be collectively described by a single-particle wave-function given by a superposition of a total ground state with energy M = Nm and Entropy 2015, 17 6894 a Planckian distribution for E > M at the same Hawking temperature. This can be used to compute the partition function and to find the usual area law for the entropy, with a logarithmic correction related to the Hawking component. The backreaction of modes with ω > m is also shown to reduce

  8. General relativistic electromagnetic and massive vector field effects with gamma-ray burst production

    Science.gov (United States)

    Tamburini, Fabrizio; De Laurentis, Mariafelicia; Amati, Lorenzo; Thidé, Bo

    2017-11-01

    We propose a new energy extraction mechanism from the rotational energy of a Kerr-Newman black hole by a gravitating massive photon field generated by electromagnetic and gravitational field coupling effects. Numerical studies show that this mechanism that depends on the black hole rotation parameter, a , shows a clear dependence on the black hole mass, M , and charge, Q , and can extract energies up to 1 054 erg for a black hole of the solar mass size. With this mechanism we can set a lower bound on the coupling ξ ˜10-38 between electromagnetic and gravitational fields that might be used to explain the hypothetical extremely high energy release, >1053 erg, suggested by the observations of some gamma-ray bursts in the controversial "energy crisis" problem if and when gamma-ray bursts seem not to show evidence for collimated emission.

  9. Interactions in Massive Colliding Wind Binaries

    Directory of Open Access Journals (Sweden)

    Michael F. Corcoran

    2012-03-01

    Full Text Available There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.

  10. On the singularities of massive superstring amplitudes

    International Nuclear Information System (INIS)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism. (orig.)

  11. On the singularities of massive superstring amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-06-04

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism.

  12. BIOTECHNOLOGY IN FRUIT GROWING

    Directory of Open Access Journals (Sweden)

    Z. Jurković

    2008-09-01

    Full Text Available Research studies in the area of biotechnologies in fruit growing started at the Agricultural Institute Osijek in 2006 with the establishment of the first experimental in vitro laboratory for micropropagation. The laboratory started an active research related to the Project "Biotechnological methods in fruit tree identification, selection and propagation" Project is part of program "Preservation and revitalization of grape and fruit autochthonous cultivars". The goal of this research is to determine genetic differences between autochthonous and introduced cultivars of cherry as well as cultivars and types of sour cherry, to find and optimize a method for fast recovery of clonal material. A great number of cherry cultivars and types within the population of cv. Oblacinska sour cherry exists in Croatia. A survey with the purpose of selecting autochthonous cultivars for further selection has been done in previous research. Differences have been found in a number of important agronomic traits within the populations of cv. Oblačinska sour cherry. Autochthonous cherry cultivars are suspected to be synonyms of known old cultivars which were introduced randomly and have been naturalized under a local name. Identification and description of cultivars and types of fruits is based on special visible properties which were measurable or notable. In this approach difficulties arise from the effect of non-genetic factors on expression of certain traits. Genetic-physiological problem of S allele autoincompatibility exists within cherry cultivars. Therefore it is necessary to put different cultivars in the plantation to pollinate each other. Apart form the fast and certain sort identification independent of environmental factors, biotechnological methods based on PCR enable faster virus detection compared with classical serologic methods and indexing and cover a wider range of plant pathogens including those undetectable by other methods. Thermotherapy and

  13. Ghost Remains After Black Hole Eruption

    Science.gov (United States)

    2009-05-01

    it has died," said co-author Scott Chapman, also of Cambridge University. "This means we don't have to catch the black holes in the act to witness the big impact they have." This is the first X-ray ghost ever seen after the demise of radio-bright jets. Astronomers have observed extensive X-ray emission with a similar origin, but only from galaxies with radio emission on large scales, signifying continued eruptions. In HDF 130, only a point source is detected in radio images, coinciding with the massive elliptical galaxy seen in its optical image. This radio source indicates the presence of a growing supermassive black hole. People Who Read This Also Read... Milky Way's Super-efficient Particle Accelerators Caught in The Act NASA Joins "Around the World in 80 Telescopes" Celebrate the International Year of Astronomy Galaxies Coming of Age in Cosmic Blobs "This result hints that the X-ray sky should be littered with such ghosts," said co-author Caitlin Casey, also of Cambridge, "especially if black hole eruptions are as common as we think they are in the early Universe." The power contained in the black hole eruption was likely to be considerable, equivalent to about a billion supernovas. The energy is dumped into the surroundings and transports and heats the gas. "Even after the ghost disappears, most of the energy from the black hole's eruption remains", said Fabian. "Because they're so powerful, these eruptions can have profound effects lasting for billions of years." The details of Chandra's data of HDF 130 helped secure its true nature. For example, in X-rays, HDF 130 has a cigar-like shape that extends for some 2.2 million light years. The linear shape of the X-ray source is consistent with the shape of radio jets and not with that of a galaxy cluster, which is expected to be circular. The energy distribution of the X-rays is also consistent with the interpretation of an X-ray ghost. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra

  14. Resíduos da agroindústria de chá preto como substrato para produção de mudas de hortaliças Agroindustry residues of the black tea as substrate for growing seedlings of vegetable crops

    Directory of Open Access Journals (Sweden)

    Juliana Domingues Lima

    2007-12-01

    %. In the growth assays, seeds were placed in trays containing: 1. vermiculite; 2. decomposed residue plus vermiculite; 3. decomposed residue and 4. crude residue washed plus vermiculite. The decomposed residue was obtained from crude residue decomposition process and the crude residue washed from crude residue washing in water. For the assays were adopted the randomized completely experimental design with four treatments and four repetitions of thirty seeds each. The results indicated that aqueous extract inhibited the seeds germination and seedlings growth of lettuce, tomato and cucumber. The crude residue washed plus vermiculite also reduced the seedlings emergency. On the other hand, the decomposed residue and decomposed residue plus vermiculite stimulated the seedlings emergency and growth. The decomposition process possibilited the use of black tea industry residue as substrate for seedlings growing of vegetable crops.

  15. Rio Blanco massive hydraulic fracture

    Energy Technology Data Exchange (ETDEWEB)

    1973-01-01

    The Piceance Basin in Colorado contains an estimated 600 trillion cu ft of natural gas in place. Both the Rulison and Rio Blanco events have been detonated to determine the feasibility of nuclear fracturing to stimulate natural gas production in this basin. A demonstration program to test the relative effectiveness of massive hydraulic fracturing (MHF) to achieve natural gas production stimulation from the same gas reservoir is presented. Details are included on MHF design parameters, including surface and subsurface equipment, pumping requirements, evaluation of fracturing results, and all associated test programs; site characteristics and preparation; proposal for gas utilization program; environmental surveillance and comparative analysis of environmental aspects of MHF and nuclear stimulation; gas delivery estimates; project administration; and costs and scheduling.

  16. Stable massive particles at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Fairbairn, M.; /Stockholm U.; Kraan, A.C.; /Pennsylvania U.; Milstead, D.A.; /Stockholm U.; Sjostrand, T.; /Lund U.; Skands, P.; /Fermilab; Sloan, T.; /Lancaster U.

    2006-11-01

    We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs, the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition are addressed.

  17. NASA Observatory Confirms Black Hole Limits

    Science.gov (United States)

    2005-02-01

    The very largest black holes reach a certain point and then grow no more, according to the best survey to date of black holes made with NASA's Chandra X-ray Observatory. Scientists have also discovered many previously hidden black holes that are well below their weight limit. These new results corroborate recent theoretical work about how black holes and galaxies grow. The biggest black holes, those with at least 100 million times the mass of the Sun, ate voraciously during the early Universe. Nearly all of them ran out of 'food' billions of years ago and went onto a forced starvation diet. Focus on Black Holes in the Chandra Deep Field North Focus on Black Holes in the Chandra Deep Field North On the other hand, black holes between about 10 and 100 million solar masses followed a more controlled eating plan. Because they took smaller portions of their meals of gas and dust, they continue growing today. "Our data show that some supermassive black holes seem to binge, while others prefer to graze", said Amy Barger of the University of Wisconsin in Madison and the University of Hawaii, lead author of the paper describing the results in the latest issue of The Astronomical Journal (Feb 2005). "We now understand better than ever before how supermassive black holes grow." One revelation is that there is a strong connection between the growth of black holes and the birth of stars. Previously, astronomers had done careful studies of the birthrate of stars in galaxies, but didn't know as much about the black holes at their centers. DSS Optical Image of Lockman Hole DSS Optical Image of Lockman Hole "These galaxies lose material into their central black holes at the same time that they make their stars," said Barger. "So whatever mechanism governs star formation in galaxies also governs black hole growth." Astronomers have made an accurate census of both the biggest, active black holes in the distance, and the relatively smaller, calmer ones closer by. Now, for the first

  18. Local energy decay of massive Dirac fields in the 5D Myers-Perry metric

    International Nuclear Information System (INIS)

    Daudé, Thierry; Kamran, Niky

    2012-01-01

    We consider massive Dirac fields evolving in the exterior region of a five-dimensional Myers-Perry black hole and study their propagation properties. Our main result states that the local energy of such fields decays in a weak sense at late times. We obtain this result in two steps: first, using the separability of the Dirac equation, we prove the absence of a pure point spectrum for the corresponding Dirac operator; second, using a new form of the equation adapted to the local rotations of the black hole, we show by a Mourre theory argument that the spectrum is absolutely continuous. This leads directly to our main result. (paper)

  19. Online gaming addiction? Motives predict addictive play behavior in massively multiplayer online role-playing games

    NARCIS (Netherlands)

    Kuss, D.J.; Louws, J.; Wiers, R.W.

    2012-01-01

    Recently, there have been growing concerns about excessive online gaming. Playing Massively Multiplayer Online Role-Playing Games (MMORPGs) appears to be particularly problematic, because these games require a high degree of commitment and time investment from the players to the detriment of

  20. What Makes a MOOC? Massive Open Online Courses (MOOCSs) Compared to Mainstream Online University Courses

    Science.gov (United States)

    Johnston, Timothy C.

    2014-01-01

    A Massive Open Online Course (MOOC) is a model for delivering learning content online to any person who wants to take a course, with no limit on attendance. The MOOC industry is growing rapidly, fueled by students interested in free higher-education learning, and the universities and venture capitalists willing to fund the courses. This paper…

  1. How realistic UV spectra and X-rays suppress the abundance of direct collapse black holes

    NARCIS (Netherlands)

    Latif, M. A.; Bovino, S.; Grassi, T.; Schleicher, D. R. G.; Spaans, M.

    Observations of high-redshift quasars at z > 6 indicate that they harbour supermassive black holes (SMBHs) of a billion solar masses. The direct collapse scenario has emerged as the most plausible way to assemble SMBHs. The nurseries for the direct collapse black holes are massive primordial haloes

  2. Measuring the accreting stellar and intermediate mass black hole populations in the Galaxy and Local Group

    NARCIS (Netherlands)

    Grindlay, J.; Barret, D.; Belloni, T.; Corbel, S.; Kaaret, P.; Allen, B.; Bazzano, A.; Berger, E.; Bignami, G.; Caraveo, P.; De Luca, A.; Fabbiano, P.; Finger, M.; Feroci, M.; Hong, J.; Jernigan, G.; van der Klis, M.; Kouveliotou, C.; Kutyrev, A.; Loeb, A.; Paizis, A.; Pareschi, G.; Skinner, G.; Di Stefano, R.; Ubertini, P.; Wilson-Hodge, C.A.

    2010-01-01

    The population of stellar black holes (SBHs) in the Galaxy and galaxies generally is poorly known in both number and distribution. SBHs are the fossil record of the massive stars in galaxy evolution and may have produced some (if not all) of the intermediate mass (≳100M⊙) black holes (IMBHs) and, in

  3. Strong-field tests of gravity using pulsars and black holes

    NARCIS (Netherlands)

    Kramer, M.; Backer, D.C.; Cordes, J.M.; Lazio, T.J.W.; Stappers, B.W.; Johnston, S.

    2004-01-01

    The sensitivity of the SKA enables a number of tests of theories of gravity. A Galactic Census of pulsars will discover most of the active pulsars in the Galaxy beamed toward us. In this census will almost certainly be pulsar black hole binaries as well as pulsars orbiting the super-massive black

  4. Reconceptualizing Successful Aging Among Black Women and the Relevance of the Strong Black Woman Archetype

    Science.gov (United States)

    Baker, Tamara A.; Buchanan, NiCole T.; Mingo, Chivon A.; Roker, Rosalyn; Brown, Candace S.

    2015-01-01

    Although there are multiple pathways to successful aging, little is known of what it means to age successfully among black women. There is a growing body of literature suggesting that black women experience a number of social challenges (sexism and racism) that may present as barriers to aging successfully. Applying aspects of the Strong Black Women ideal, into theoretical concepts of successful aging, may be particularly relevant in understanding which factors impair or promote the ability of black women to age successfully. The Strong Black Women archetype is a culturally salient ideal prescribing that black women render a guise of self-reliance, selflessness, and psychological, emotional, and physical strength. Although this ideal has received considerable attention in the behavioral sciences, it has been largely absent within the gerontology field. Nevertheless, understanding the dynamics of this cultural ideal may enhance our knowledge while developing an appreciation of the black woman’s ability to age successfully. Rather than summarize the social, physical, and mental health literature focusing on health outcomes of black women, this conceptual review examines the Strong Black Women archetype and its application to the lived experiences of black women and contributions to current theories of successful aging. Focusing on successful aging exclusively among black women enhances our understanding of this group by considering their identity as women of color while recognizing factors that dictate their ability to age successfully. PMID:25416685

  5. Instability of a colored black hole solution

    International Nuclear Information System (INIS)

    Straumann, N.; Zhou Zhihong

    1990-01-01

    We analyze the stability of a black hole solution of the Einstein-Yang-Mills equations that was recently found numerically by Bizon, and which provides a counter example for the 'no hair' conjecture for non-abelian black holes. In the framework of small time-dependent perturbations it is shown that there is at least one exponentially growing radial mode with the correct boundary conditions at the horizon and at infinity. (orig.)

  6. Massive boson-fermion degeneracy and the early structure of the universe

    International Nuclear Information System (INIS)

    Kounnas, C.

    2008-01-01

    The existence of a new kind of massive boson-fermion symmetry is shown explicitly in the framework of the heterotic, type II and type II orientifold superstring theories. The target space-time is two-dimensional. Higher dimensional models are defined via large marginal deformations of J anti J-type. The spectrum of the initial undeformed two dimensional vacuum consists of massless boson degrees of freedom, while all massive boson and fermion degrees of freedom exhibit a new Massive Spectrum Degeneracy Symmetry (MSDS). This precise property, distinguishes the MSDS theories from the well known supersymmetric SUSY-theories. Some proposals are stated in the framework of these theories concerning the structure of: (i) The Early Non-singular Phase of the Universe, (ii) The two dimensional boundary theory of AdS 3 Black-Holes, (iii) Plausible applications of the MSDS theories in particle physics, alternative to SUSY. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  7. Massive Star Burps, Then Explodes

    Science.gov (United States)

    2007-04-01

    Berkeley -- In a galaxy far, far away, a massive star suffered a nasty double whammy. On Oct. 20, 2004, Japanese amateur astronomer Koichi Itagaki saw the star let loose an outburst so bright that it was initially mistaken for a supernova. The star survived, but for only two years. On Oct. 11, 2006, professional and amateur astronomers witnessed the star actually blowing itself to smithereens as Supernova 2006jc. Swift UVOT Image Swift UVOT Image (Credit: NASA / Swift / S.Immler) "We have never observed a stellar outburst and then later seen the star explode," says University of California, Berkeley, astronomer Ryan Foley. His group studied the event with ground-based telescopes, including the 10-meter (32.8-foot) W. M. Keck telescopes in Hawaii. Narrow helium spectral lines showed that the supernova's blast wave ran into a slow-moving shell of material, presumably the progenitor's outer layers ejected just two years earlier. If the spectral lines had been caused by the supernova's fast-moving blast wave, the lines would have been much broader. artistic rendering This artistic rendering depicts two years in the life of a massive blue supergiant star, which burped and spewed a shell of gas, then, two years later, exploded. When the supernova slammed into the shell of gas, X-rays were produced. (Credit: NASA/Sonoma State Univ./A.Simonnet) Another group, led by Stefan Immler of NASA's Goddard Space Flight Center, Greenbelt, Md., monitored SN 2006jc with NASA's Swift satellite and Chandra X-ray Observatory. By observing how the supernova brightened in X-rays, a result of the blast wave slamming into the outburst ejecta, they could measure the amount of gas blown off in the 2004 outburst: about 0.01 solar mass, the equivalent of about 10 Jupiters. "The beautiful aspect of our SN 2006jc observations is that although they were obtained in different parts of the electromagnetic spectrum, in the optical and in X-rays, they lead to the same conclusions," says Immler. "This

  8. High-redshift supermassive black holes: accretion through cold flows

    Science.gov (United States)

    Feng, Yu; Di Matteo, Tiziana; Croft, Rupert; Khandai, Nishikanta

    2014-05-01

    We use zoom-in techniques to re-simulate three high-redshift (z ≥ 5.5) haloes which host 109 M⊙ black holes from the ˜Gpc volume, MassiveBlack cosmological hydrodynamic simulation. We examine a number of factors potentially affecting supermassive black hole growth at high redshift in cosmological simulations. We find insignificant differences in the black hole accretion history by (i) varying the region over which feedback energy is deposited directly, (ii) changing mass resolution by factors of up to 64, (iii) changing the black hole seed mass by a factor of 100. Switching from the density-entropy formulation to the pressure-entropy formulation of smoothed particle hydrodynamics slightly increases the accretion rate. In general numerical details/model parameters appear to have small effects on the main fuelling mechanism for black holes at these high redshifts. The insensitivity to simulation technique seems to be a hallmark of the cold flow feeding picture of these high-z supermassive black holes. We show that the gas that participates in critical accretion phases in these massive objects at z > 6-7 is in all cases colder, denser and forms more coherent streams than the average gas in the halo. This is also mostly the case when the black hole accretion is feedback regulated (z < 6), however, the distinction is less prominent. For our resimulated haloes, cold flows appear to be a viable mechanism for forming the most massive black holes in the early universe, occurring naturally in Λ cold dark matter models of structure formation, without requiring fine-tuning of numerical parameters.

  9. 10 billion years of massive Galaxies

    NARCIS (Netherlands)

    Taylor, Edward Nairne Cunningham

    2009-01-01

    The most massive galaxies in the local universe are not forming new stars -- but we don’t know why. As a step towards figuring out why big galaxies stop forming stars, we set out to measure when they stop forming stars. By looking at the colors of massive galaxies have changed over 10 billion

  10. Massive rectal bleeding from colonic diverticulosis | Olokoba ...

    African Journals Online (AJOL)

    Objectives: This is to describe a case of colonic diverticulosis causing massive rectal bleeding in an elderly Nigerian man. Case report: We highlight a case of a 79 year old man who presented with massive rectal bleeding due to colonic diverticulosis from our centre. Colonoscopy identified multiple diverticula in the ...

  11. Management of massive haemoptysis | Adegboye | Nigerian Journal ...

    African Journals Online (AJOL)

    Background: This study compares two management techniques in the treatment of massive haemotysis. Method: All patients with massive haemoptysis treated between January 1969 and December 1980 (group 1) were retrospectively reviewed and those prospectively treated between January 1981 and August 1999 ...

  12. An effective theory of massive gauge bosons

    International Nuclear Information System (INIS)

    Doria, R.M.; Helayel Neto, J.A.

    1986-01-01

    The coupling of a group-valued massive scalar field to a gauge field through a symmetric rank-2 field strenght is studied. By considering energies very small compared with the mass of the scalar and invoking the decoupling theorem, one is left with a low-energy effective theory describing a dynamics of massive vector fields. (Author) [pt

  13. On the singularities of massive superstring amplitudes

    NARCIS (Netherlands)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are

  14. Massive rectal bleeding from colonic diverticulosis

    African Journals Online (AJOL)

    ABEOLUGBENGAS

    Objectives: This is to describe a case of colonic diverticulosis causing massive rectal bleeding in an elderly Nigerian man. ... also oozing blood. He was worked up, and had surgery for hemicolectomy due to massive blood loss following failure of initial conservative management. .... bleeding patterns observed in fifty cases.

  15. An unstable truth: how massive stars get their mass

    Science.gov (United States)

    Rosen, Anna L.; Krumholz, Mark R.; McKee, Christopher F.; Klein, Richard I.

    2016-12-01

    The pressure exerted by massive stars' radiation fields is an important mechanism regulating their formation. Detailed simulation of massive star formation therefore requires an accurate treatment of radiation. However, all published simulations have either used a diffusion approximation of limited validity; have only been able to simulate a single star fixed in space, thereby suppressing potentially important instabilities; or did not provide adequate resolution at locations where instabilities may develop. To remedy this, we have developed a new, highly accurate radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. We use our new tool to perform 3D radiation-hydrodynamic simulations of the collapse of massive pre-stellar cores with laminar and turbulent initial conditions and properly resolve regions where we expect instabilities to grow. We find that mass is channelled to the stellar system via gravitational and Rayleigh-Taylor (RT) instabilities, in agreement with previous results using stars capable of moving, but in disagreement with methods where the star is held fixed or with simulations that do not adequately resolve the development of RT instabilities. For laminar initial conditions, proper treatment of the direct radiation field produces later onset of instability, but does not suppress it entirely provided the edges of radiation-dominated bubbles are adequately resolved. Instabilities arise immediately for turbulent pre-stellar cores because the initial turbulence seeds the instabilities. Our results suggest that RT features should be present around accreting massive stars throughout their formation.

  16. Black Hole Universe Model and Dark Energy

    Science.gov (United States)

    Zhang, Tianxi

    2011-01-01

    Considering black hole as spacetime and slightly modifying the big bang theory, the author has recently developed a new cosmological model called black hole universe, which is consistent with Mach principle and Einsteinian general relativity and self consistently explains various observations of the universe without difficulties. According to this model, the universe originated from a hot star-like black hole and gradually grew through a supermassive black hole to the present universe by accreting ambient material and merging with other black holes. The entire space is infinitely and hierarchically layered and evolves iteratively. The innermost three layers are the universe that we lives, the outside space called mother universe, and the inside star-like and supermassive black holes called child universes. The outermost layer has an infinite radius and zero limits for both the mass density and absolute temperature. All layers or universes are governed by the same physics, the Einstein general relativity with the Robertson-Walker metric of spacetime, and tend to expand outward physically. When one universe expands out, a new similar universe grows up from its inside black holes. The origin, structure, evolution, expansion, and cosmic microwave background radiation of black hole universe have been presented in the recent sequence of American Astronomical Society (AAS) meetings and published in peer-review journals. This study will show how this new model explains the acceleration of the universe and why dark energy is not required. We will also compare the black hole universe model with the big bang cosmology.

  17. Bringing Black Holes Together: How Supermassive Black Hole Binaries Form and Plunge Through the Final Parsec

    Science.gov (United States)

    Holley-Bockelmann, Kelly

    2016-04-01

    Astronomers now know that supermassive black holes reside in nearly every galaxy.Though these black holes are an observational certainty, nearly every aspect of their evolution -- from their birth, to their fuel source, to their basic dynamics -- is a matter of lively debate. In principle, gas-rich major galaxy mergers can generate the central stockpile of fuel needed for a low mass central black hole seed to grow quickly into a supermassive one. During a galaxy merger, the black holes in each galaxy meet and form a supermassive binary black hole; as the binary orbit shrinks through its final parsec, it becomes the loudest gravitational wave source in the Universe and a powerful agent to sculpt the galactic center. This talk will touch on some current and ongoing work on refining our theories of how supermassive black hole binaries form, evolve within, and alter their galaxy host.

  18. Electrical properties of seafloor massive sulfides

    Science.gov (United States)

    Spagnoli, Giovanni; Hannington, Mark; Bairlein, Katharina; Hördt, Andreas; Jegen, Marion; Petersen, Sven; Laurila, Tea

    2016-06-01

    Seafloor massive sulfide (SMS) deposits are increasingly seen as important marine metal resources for the future. A growing number of industrialized nations are involved in the surveying and sampling of such deposits by drilling. Drill ships are expensive and their availability can be limited; seabed drill rigs are a cost-effective alternative and more suitable for obtaining cores for resource evaluation. In order to achieve the objectives of resource evaluations, details are required of the geological, mineralogical, and physical properties of the polymetallic deposits and their host rocks. Electrical properties of the deposits and their ore minerals are distinct from their unmineralized host rocks. Therefore, the use of electrical methods to detect SMS while drilling and recovering drill cores could decrease the costs and accelerate offshore operations by limiting the amount of drilling in unmineralized material. This paper presents new data regarding the electrical properties of SMS cores that can be used in that assessment. Frequency-dependent complex electrical resistivity in the frequency range between 0.002 and 100 Hz was examined in order to potentially discriminate between different types of fresh rocks, alteration and mineralization. Forty mini-cores of SMS and unmineralized host rocks were tested in the laboratory, originating from different tectonic settings such as the intermediate-spreading ridges of the Galapagos and Axial Seamount, and the Pacmanus back-arc basin. The results indicate that there is a clear potential to distinguish between mineralized and non-mineralized samples, with some evidence that even different types of mineralization can be discriminated. This could be achieved using resistivity magnitude alone with appropriate rig-mounted electrical sensors. Exploiting the frequency-dependent behavior of resistivity might amplify the differences and further improve the rock characterization.

  19. Hydrodynamic and hydromagnetic stability of black holes with ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Subrahmanyan Chandrasekhar (Chandra) was just eight years old when the first astrophysical jet was discovered in M87. Since then, jets have been uncovered with a wide variety of sources including accretion disks orbiting stellar and massive black holes, neutron stars, isolated pulsars, -ray bursts, ...

  20. Hydrodynamic and hydromagnetic stability of black holes with ...

    Indian Academy of Sciences (India)

    Abstract. Subrahmanyan Chandrasekhar (Chandra) was just eight years old when the first astro- physical jet was discovered in M87. Since then, jets have been uncovered with a wide variety of sources including accretion disks orbiting stellar and massive black holes, neutron stars, iso- lated pulsars, γ-ray bursts, protostars ...

  1. Condensate of massive graviton and dark matter

    Science.gov (United States)

    Aoki, Katsuki; Maeda, Kei-ichi

    2018-02-01

    We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first define the effective energy-momentum tensor of the coherent massive gravitons in a curved spacetime. We then study the background dynamics of the Universe and the cosmic structure formation including the effects of the coherent massive gravitons. We find that the condensate of the massive graviton behaves as a dark matter component of the Universe. From the geometrical point of view the condensate is regarded as a spacetime anisotropy. Hence, in our scenario, dark matter is originated from the tiny deformation of the spacetime. We also discuss a production of the spacetime anisotropy and find that the extragalactic magnetic field of a primordial origin can yield a sufficient amount for dark matter.

  2. Quasi-local conserved charges of spin-3 topologically massive gravity

    Directory of Open Access Journals (Sweden)

    M.R. Setare

    2016-08-01

    Full Text Available In this paper we obtain conserved charges of spin-3 topologically massive gravity by using a quasi-local formalism. We find a general formula to calculate conserved charge of the spin-3 topologically massive gravity which corresponds to a Killing vector field ξ. We show that this general formula reduces to the previous one for the ordinary spin-3 gravity presented in [18] when we take into account only transformation under diffeomorphism, without considering generalized Lorentz gauge transformation (i.e. λξ=0, and by taking 1μ→0. Then we obtain a general formula for the entropy of black hole solutions of the spin-3 topologically massive gravity. Finally we apply our formalism to calculate energy, angular momentum and entropy of a special black hole solution and we find that obtained results are consistent with previous results in the limiting cases. Moreover our results for energy, angular momentum and entropy are consistent with the first law of black hole mechanics.

  3. New massive gravity and AdS(4) counterterms.

    Science.gov (United States)

    Jatkar, Dileep P; Sinha, Aninda

    2011-04-29

    We show that the recently proposed Dirac-Born-Infeld extension of new massive gravity emerges naturally as a counterterm in four-dimensional anti-de Sitter space (AdS(4)). The resulting on-shell Euclidean action is independent of the cutoff at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS(4) Schwarzschild black hole entropy in a cutoff-independent manner. The parameter values of the resulting counterterm action correspond to a c=0 theory in the context of the duality between AdS(3) gravity and two-dimensional conformal field theory. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory.

  4. Evolution of a massive binary in a star field

    International Nuclear Information System (INIS)

    Baranov, A.S.

    1984-01-01

    The orbital evolution of a massive binary system interacting with a background field of single stars whose phase density is homogeneous in configuration space is considered. The velocity distribution is assumed isotropic up to some limiting value, and a typical field star is regarded as having a velocity much higher than the orbital speed of the pair components. An expression is derived for the transfer of energy from the binary to the field stars. The time evolution of the orbit parameters a, e is established, and the evolution rate is estimated for Kardashev's (1983) model galactic nucleus containing a central black-hole binary. On the above assumptions the components should become twice as close together within only a few tens of millennia, although the picture may change fundamentally if the nucleus is rotating. 13 references

  5. Merger rates of black hole binaries: prospects for gravitational wave detectors

    OpenAIRE

    Zwart, Simon Portegies; McMillan, Stephen

    1999-01-01

    Mergers of black-hole binaries are expected to release large amounts of energy in the form of gravitational radiation. However, binary evolution models predict merger rates too low to be of observational interest. In this paper we explore the possibility that black holes become members of close binaries via dynamical interactions with other stars in dense stellar systems. In star clusters, black holes become the most massive objects within a few tens of millions of years; dynamical relaxation...

  6. On the Mass Distribution of Stellar-Mass Black Holes

    Directory of Open Access Journals (Sweden)

    Malkov O. Yu.

    2014-12-01

    Full Text Available The observational stellar-mass black hole mass distribution exhibits a maximum at about 8 M⊙. It can be explained via the details of the massive star evolution, supernova explosions, or consequent black hole evolution. We propose another explanation, connected with an underestimated influence of the relation between the initial stellar mass and the compact remnant mass. We show that an unimodal observational mass distribution of black holes can be produced by a power-law initial mass function and a monotonic “remnant mass versus initial mass” relation.

  7. Thermodynamics of higher dimensional black holes

    Energy Technology Data Exchange (ETDEWEB)

    Accetta, F.S.; Gleiser, M.

    1986-05-01

    We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs.

  8. Thermodynamics of higher dimensional black holes

    International Nuclear Information System (INIS)

    Accetta, F.S.; Gleiser, M.

    1986-05-01

    We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs

  9. Black hole formation in a contracting universe

    International Nuclear Information System (INIS)

    Quintin, Jerome; Brandenberger, Robert H.

    2016-01-01

    We study the evolution of cosmological perturbations in a contracting universe. We aim to determine under which conditions density perturbations grow to form large inhomogeneities and collapse into black holes. Our method consists in solving the cosmological perturbation equations in complete generality for a hydrodynamical fluid. We then describe the evolution of the fluctuations over the different length scales of interest and as a function of the equation of state for the fluid, and we explore two different types of initial conditions: quantum vacuum and thermal fluctuations. We also derive a general requirement for black hole collapse on sub-Hubble scales, and we use the Press-Schechter formalism to describe the black hole formation probability. For a fluid with a small sound speed (e.g., dust), we find that both quantum and thermal initial fluctuations grow in a contracting universe, and the largest inhomogeneities that first collapse into black holes are of Hubble size and the collapse occurs well before reaching the Planck scale. For a radiation-dominated fluid, we find that no black hole can form before reaching the Planck scale. In the context of matter bounce cosmology, it thus appears that only models in which a radiation-dominated era begins early in the cosmological evolution are robust against the formation of black holes. Yet, the formation of black holes might be an interesting feature for other models. We comment on a number of possible alternative early universe scenarios that could take advantage of this feature.

  10. The link between galaxy and black hole growth in the eagle simulation

    Science.gov (United States)

    McAlpine, Stuart; Bower, Richard G.; Harrison, Chris M.; Crain, Robert A.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

    2017-07-01

    We investigate the connection between the star formation rate (SFR) of galaxies and their central black hole accretion rate (BHAR) using the eagle cosmological hydrodynamical simulation. We find, in striking concurrence with recent observational studies, that the -BHAR relation for an active galactic nucleus (AGN)-selected sample produces a relatively flat trend, whilst the -SFR relation for an SFR-selected sample yields an approximately linear trend. These trends remain consistent with their instantaneous equivalents even when both SFR and BHAR are time averaged over a period of 100 Myr. There is no universal relationship between the two growth rates. Instead, SFR and BHAR evolve through distinct paths that depend strongly on the mass of the host dark matter halo. The galaxies hosted by haloes of mass M200 ≲ 1011.5 M⊙ grow steadily, yet black holes (BHs) in these systems hardly grow, yielding a lack of correlation between SFR and BHAR. As haloes grow through the mass range 1011.5 ≲ M200 ≲ 1012.5 M⊙ BHs undergo a rapid phase of non-linear growth. These systems yield a highly non-linear correlation between the SFR and BHAR, which are non-causally connected via the mass of the host halo. In massive haloes (M200 ≳ 1012.5 M⊙), both SFR and BHAR decline on average with a roughly constant scaling of SFR/BHAR ˜ 103. Given the complexity of the full SFR-BHAR plane built from multiple behaviours, and from the large dynamic range of BHARs, we find the primary driver of the different observed trends in the -BHAR and -SFR relationships are due to sampling considerably different regions of this plane.

  11. Massive pneumoperitoneum after scuba diving.

    Science.gov (United States)

    Oh, Seung-Tak; Kim, Wook; Jeon, Hae-Myung; Kim, Jeong-Soo; Kim, Kee-Whan; Yoo, Seung-Jin; Kim, Eung-Kuk

    2003-01-01

    Pneumoperitoneum usually indicates rupture of a hollow viscus and considered a surgical emergency. But air may also enter the peritoneum from the lung or the genital organs in female without visceral perforation. While scuba diving, the rapid ascent is usually controlled by placing in a decompression chamber and the excess gas volume is exhaled. Failure to allow this excess gas to escape will result in overdistension of air passage, which may rupture resulting in pulmonary interstitial emphysema or, if air enters the circulation, air embolus can occur. Pneumo-peritoneum is a rare complication of diving accidents. While the majority of cases are not related to an intraabdominal catastrophy, more than 20% have been the result of gastric rupture. We report a 42-yr-old male patient with massive pneumoperitoneum after scuba diving, who presented himself with dyspnea and abdominal distension. Knowledge of this rare condition and its benign course may allow the emergency physician and surgeon to order appropriate studies to help avoid unnecessary surgical treatment. It is important to determine promptly whether the air emanated from a ruptured viscus or was introduced from an extraperitoneal source. Free air in the abdomen does not always indicate a ruptured intra-abdominal viscus. PMID:12692430

  12. How can young massive clusters reach their present-day sizes?

    Science.gov (United States)

    Banerjee, Sambaran; Kroupa, Pavel

    2017-01-01

    Context. The classic question of how young massive star clusters attain the shapes and sizes, as we find them today, is still a difficult one. Both observational and computational studies of star-forming massive molecular gas clouds suggest that massive cluster formation is primarily triggered along the small-scale (≲0.3 pc) filamentary substructures within the clouds. Aims: The present study investigates the possible ways in which a filament-like, compact, massive star cluster (effective radius 0.1-0.3 pc) can expand more than 10 times, still remaining massive enough (≳ 104M⊙) to become the young massive star cluster that we observe today. Methods: To this end, model massive clusters (initially 104-105M⊙) are evolved using Sverre Aarseth's state-of-the-art N-body code NBODY7. Apart from the accurate calculation of two-body relaxation of the constituent stars, these evolutionary models take into account stellar-evolutionary mass loss and dynamical energy injection due to massive, tight primordial binaries and stellar-remnant black holes and neutron stars. These calculations also include a solar-neighbourhood-like external tidal field. All the computed clusters expand with time, and their sizes (effective radii) are compared with those observed for young massive clusters (≲ 100 Myr) in the Milky Way and other nearby galaxies. Results: In this study, it is found that beginning from the above compact sizes, a star cluster cannot expand on its own, I.e., due to two-body relaxation, stellar mass loss, and dynamical heating by primordial binaries and compact stars up to the observed sizes of young massive clusters; star clusters always remain much more compact than the observed ones. Conclusions: This calls for additional mechanisms that boost the expansion of a massive cluster after its assembly. Using further N-body calculations, it is shown that a substantial residual gas expulsion with ≈ 30% star formation efficiency can indeed swell the newborn embedded

  13. Spitzer Observations of Massive, Red Galaxies at High Redshift

    Science.gov (United States)

    Papovich, C.; Moustakas, L. A.; Dickinson, M.; Le Floc'h, E.; Rieke, G. H.; Daddi, E.; Alexander, D. M.; Bauer, F.; Brandt, W. N.; Dahlen, T.; Egami, E.; Eisenhardt, P.; Elbaz, D.; Ferguson, H. C.; Giavalisco, M.; Lucas, R. A.; Mobasher, B.; Pérez-González, P. G.; Stutz, A.; Rieke, M. J.; Yan, H.

    2006-03-01

    We study massive galaxies at z~1-3.5 using HST optical imaging, ground-based near-IR imaging, and Spitzer observations at 3-24 μm. From Ks-selected galaxies in the ~=130 arcmin2 GOODS-S field, we identify 153 distant red galaxies (DRGs) with (J-Ks)Vega>=2.3. This sample is approximately complete in stellar mass for passively evolving galaxies above 1011 Msolar and z~4-6 mag) starbursts (at zmed~1.7). Very few DRGs (=1011 Msolar have specific star formation rates (SFRs per unit mass) including the reradiated far-IR emission that range from 0.2 to 10 Gyr-1. Based on the X-ray luminosities and rest-frame near-IR colors, roughly one-quarter of the DRGs contain AGNs, implying that the growth of supermassive black holes coincides with the formation of massive galaxies. At 1.5=1011 Msolar have an integrated specific SFR comparable to the global value of all galaxies. In contrast, galaxies at z~0.3-0.75 with M>=1011 Msolar have an integrated specific SFR less than the global value and more than an order of magnitude lower than that for massive DRGs. At zcontract 1407; on observations taken with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555 and on observations collected at the Kitt Peak National Observatory (KPNO), National Optical Astronomical Observatory (NOAO), which is operated by AURA, Inc., under cooperative agreement with the National Science Foundation. Observations have also been carried out using the Very Large Telescope at the ESO Paranal Observatory under program ID LP168.A-0485.

  14. Black holes in binary stellar systems and galactic nuclei

    International Nuclear Information System (INIS)

    Cherepashchuk, A M

    2014-01-01

    In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M BH =(4−20)M ⊙ ) in X-ray binary systems and of several hundred supermassive black holes (M BH =(10 6 −10 10 )M ⊙ ) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a ∗ have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a ∗ =0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths λ≲1 mm (the international program, Event Horizon Telescope). (100

  15. Water potential in ponderosa pine stands of different growing-stock levels

    Science.gov (United States)

    J. M. Schmid; S. A. Mata; R. K. Watkins; M. R. Kaufmann

    1991-01-01

    Water potential was measured in five ponderosa pine (Pinus ponderosa Laws.) in each of four stands of different growing-stock levels at two locations in the Black Hills of South Dakota. Mean water potentials at dawn and midday varied significantly among growing-stock levels at one location, but differences were not consistent. Mean dawn and midday water potentials...

  16. Erratic Black Hole Regulates Itself

    Science.gov (United States)

    2009-03-01

    New results from NASA's Chandra X-ray Observatory have made a major advance in explaining how a special class of black holes may shut off the high-speed jets they produce. These results suggest that these black holes have a mechanism for regulating the rate at which they grow. Black holes come in many sizes: the supermassive ones, including those in quasars, which weigh in at millions to billions of times the mass of the Sun, and the much smaller stellar-mass black holes which have measured masses in the range of about 7 to 25 times the Sun's mass. Some stellar-mass black holes launch powerful jets of particles and radiation, like seen in quasars, and are called "micro-quasars". The new study looks at a famous micro-quasar in our own Galaxy, and regions close to its event horizon, or point of no return. This system, GRS 1915+105 (GRS 1915 for short), contains a black hole about 14 times the mass of the Sun that is feeding off material from a nearby companion star. As the material swirls toward the black hole, an accretion disk forms. This system shows remarkably unpredictable and complicated variability ranging from timescales of seconds to months, including 14 different patterns of variation. These variations are caused by a poorly understood connection between the disk and the radio jet seen in GRS 1915. Chandra, with its spectrograph, has observed GRS 1915 eleven times since its launch in 1999. These studies reveal that the jet in GRS 1915 may be periodically choked off when a hot wind, seen in X-rays, is driven off the accretion disk around the black hole. The wind is believed to shut down the jet by depriving it of matter that would have otherwise fueled it. Conversely, once the wind dies down, the jet can re-emerge. "We think the jet and wind around this black hole are in a sort of tug of war," said Joseph Neilsen, Harvard graduate student and lead author of the paper appearing in the journal Nature. "Sometimes one is winning and then, for reasons we don

  17. Nonsingular universe in massive gravity's rainbow

    Science.gov (United States)

    Hendi, S. H.; Momennia, M.; Eslam Panah, B.; Panahiyan, S.

    2017-06-01

    One of the fundamental open questions in cosmology is whether we can regard the universe evolution without singularity like a Big Bang or a Big Rip. This challenging subject stimulates one to regard a nonsingular universe in the far past with an arbitrarily large vacuum energy. Considering the high energy regime in the cosmic history, it is believed that Einstein gravity should be corrected to an effective energy dependent theory which could be acquired by gravity's rainbow. On the other hand, employing massive gravity provided us with solutions to some of the long standing fundamental problems of cosmology such as cosmological constant problem and self acceleration of the universe. Considering these aspects of gravity's rainbow and massive gravity, in this paper, we initiate studying FRW cosmology in the massive gravity's rainbow formalism. At first, we show that although massive gravity modifies the FRW cosmology, but it does not itself remove the big bang singularity. Then, we generalize the massive gravity to the case of energy dependent spacetime and find that massive gravity's rainbow can remove the early universe singularity. We bring together all the essential conditions for having a nonsingular universe and the effects of both gravity's rainbow and massive gravity generalizations on such criteria are determined.

  18. Making Blackness, Making Policy

    OpenAIRE

    Geller, Peter

    2012-01-01

    Too often the acknowledgment that race is a social construction ignores exactly how this construction occurs. By illuminating the way in which the category of blackness and black individuals are made, we can better see how race matters in America. Antidiscrimination policy, social science research, and the state's support of its citizens can all be improved by an accurate and concrete definition of blackness. Making Blackness, Making Policy argues that blackness and black people are literally...

  19. Complexity-action duality of the shock wave geometry in a massive gravity theory

    Science.gov (United States)

    Miao, Yan-Gang; Zhao, Long

    2018-01-01

    On the holographic complexity dual to the bulk action, we investigate the action growth for a shock wave geometry in a massive gravity theory within the Wheeler-DeWitt (WDW) patch at the late time limit. For a global shock wave, the graviton mass does not affect the action growth in the bulk, i.e., the complexity on the boundary, showing that the action growth (complexity) is the same for both the Einstein gravity and the massive gravity. Nevertheless, for a local shock wave that depends on transverse coordinates, the action growth (complexity) caused by the boundary disturbance (perturbation) is proportional to the butterfly velocity for the two gravity theories, but the butterfly velocity of the massive gravity theory is smaller than that of the Einstein gravity theory, indicating that the action growth (complexity) of the massive gravity is depressed by the graviton mass. In addition, we extend the black hole thermodynamics of the massive gravity and obtain the right Smarr formula.

  20. Venus - Volcano With Massive Landslides

    Science.gov (United States)

    1992-01-01

    This Magellan full-resolution mosaic which covers an area 143 by 146 kilometers (89 by 91 miles) is centered at 55 degrees north latitude, 266 degrees east longitude. The bright feature, slightly south of center is interpreted to be a volcano, 15-20 kilometers (9.3 to 12.4 miles) in diameter with a large apron of blocky debris to its right and some smaller aprons to its left. A preferred explanation is that several massive catastrophic landslides dropped down steep slopes and were carried by their momentum out into the smooth, dark lava plains. At the base of the east-facing or largest scallop on the volcano is what appears to be a large block of coherent rock, 8 to 10 kilometers (5 to 6 miles) in length. The similar margin of both the scallop and block and the shape in general is typical of terrestrial slumped blocks (masses of rock which slide and rotate down a slope instead of breaking apart and tumbling). The bright lobe to the south of the volcano may either be a lava flow or finer debris from other landslides. This volcanic feature, characterized by its scalloped flanks is part of a class of volcanoes called scalloped or collapsed domes of which there are more than 80 on Venus. Based on the chute-like shapes of the scallops and the existence of a spectrum of intermediate to well defined examples, it is hypothesized that all of the scallops are remnants of landslides even though the landslide debris is often not visible. Possible explanations for the missing debris are that it may have been covered by lava flows, the debris may have weathered or that the radar may not be recognizing it because the individual blocks are too small

  1. Black Holes in Gamma Ray Bursts and Galactic Nuclei

    Science.gov (United States)

    Ruffini, Remo; Argüelles, C. R.; Fraga, B. M. O.; Geralico, A.; Quevedo, H.; Rueda, J. A.; Siutsou, I.

    2013-09-01

    Current research marks a clear success in identifying the moment of formation of a Black Hole of 10M⊙, with the emission of a Gamma Ray Burst. This explains in terms of the 'Blackholic Energy' the source of the energy of these astrophysical systems. Their energetics up to 1054 erg, make them detectable all over our Universe. Concurrently a new problematic has been arising related to: (a) The evidence of Dark Matter in galactic halos; (b) The origin of the Super Massive Black Holes in active galactic nuclei and Quasars and (c) The purported existence of a Black Hole in the Center of our Galaxy. These three aspects of this new problematic have been traditionally approached independently. We propose an unified approach to all three of them based on a system of massive self-gravitating neutrinos in General Relativity. Perspectives of future research are presented.

  2. Using massive digital libraries a LITA guide

    CERN Document Server

    Weiss, Andrew

    2014-01-01

    Some have viewed the ascendance of the digital library as some kind of existential apocalypse, nothing less than the beginning of the end for the traditional library. But Weiss, recognizing the concept of the library as a ""big idea"" that has been implemented in many ways over thousands of years, is not so gloomy. In this thought-provoking and unabashedly optimistic book, he explores how massive digital libraries are already adapting to society's needs, and looks ahead to the massive digital libraries of tomorrow, coveringThe author's criteria for defining massive digital librariesA history o

  3. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Black holes; numerical relativity; nonlinear sigma. Abstract. Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. ... Theoretical and Computational Studies Group, Southampton College, Long Island University, Southampton, NY 11968, USA ...

  4. Lagrangian formulation of massive fermionic totally antisymmetric tensor field theory in AdSd space

    International Nuclear Information System (INIS)

    Buchbinder, I.L.; Krykhtin, V.A.; Ryskina, L.L.

    2009-01-01

    We apply the BRST approach, developed for higher spin field theories, to Lagrangian construction for totally antisymmetric massive fermionic fields in AdS d space. As well as generic higher spin massive theories, the obtained Lagrangian theory is a reducible gauge model containing, besides the basic field, a number of auxiliary (Stueckelberg) fields and the order of reducibility grows with the value of the rank of the antisymmetric field. However, unlike the generic higher spin theory, for the special case under consideration we show that one can get rid of all the auxiliary fields and the final Lagrangian for fermionic antisymmetric field is formulated only in terms of basic field.

  5. A Lifshitz black hole in four dimensional R2 gravity

    International Nuclear Information System (INIS)

    Cai Ronggen; Liu Yan; Sun Yawen

    2009-01-01

    We consider a higher derivative gravity theory in four dimensions with a negative cosmological constant and show that vacuum solutions of both Lifshitz type and Schroedinger type with arbitrary dynamical exponent z exist in this system. Then we find an analytic black hole solution which asymptotes to the vacuum Lifshitz solution with z = 3/2 at a specific value of the coupling constant. We analyze the thermodynamic behavior of this black hole and find that the black hole has zero entropy while non-zero temperature, which is very similar to the case of BTZ black holes in new massive gravity at a specific coupling. In addition, we find that the three dimensional Lifshitz black hole recently found by E. Ayon-Beato et al. has a negative entropy and mass when the Newton constant is taken to be positive.

  6. Scalar clouds around Kerr–Sen black holes

    International Nuclear Information System (INIS)

    Huang, Yang; Liu, Dao-Jun; Zhai, Xiang-Hua; Li, Xin-Zhou

    2017-01-01

    In this paper, the behaviour of a charged massive scalar test field in the background of a Kerr–Sen black hole is investigated. A type of stationary solutions, dubbed scalar clouds, are obtained numerically and expressed by the existence lines in the parameter space. We show that for fixed background and a given set of harmonic indices, the mass and charge of the scalar clouds are limited in a finite region in the parameter space of the scalar field. Particularly, the maximum values of the mass and charge of the clouds around extremal Kerr–Sen black holes are independent of the angular velocity of the black hole, whereas those in the extremal Kerr–Newman background depend on the angular velocity. In addition, it is demonstrated that, as the static limit of the Kerr–Sen black hole, the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole cannot support scalar cloud. (paper)

  7. Black Holes, the Brightest Objects in the Universe

    Energy Technology Data Exchange (ETDEWEB)

    McKinney, Jonathan (Stanford University)

    2009-04-28

    Black holes are everywhere in the Universe. They form when massive stars end their life in a simultaneous violent collapse and energetic explosion. Galaxies end up littered with small black holes, each roughly the mass of ten Suns. Nearly every galaxy center ends up with a single huge black hole, with the mass of a million to a billion Suns. During their lifetimes, black holes chew up their surroundings and spew out ultra-energetic beams of radiation and matter that are visible from across the Universe. In this lecture, I will discuss how black holes form, outline how we detect them, and show movies that illustrate how they work according to Einstein and state-of-the-art computer simulations. We will see that these blackest of all objects in the Universe actually shine the brightest.

  8. Black-hole bombs and photon-mass bounds.

    Science.gov (United States)

    Pani, Paolo; Cardoso, Vitor; Gualtieri, Leonardo; Berti, Emanuele; Ishibashi, Akihiro

    2012-09-28

    Generic extensions of the standard model predict the existence of ultralight bosonic degrees of freedom. Several ongoing experiments are aimed at detecting these particles or constraining their mass range. Here we show that massive vector fields around rotating black holes can give rise to a strong superradiant instability, which extracts angular momentum from the hole. The observation of supermassive spinning black holes imposes limits on this mechanism. We show that current supermassive black-hole spin estimates provide the tightest upper limits on the mass of the photon (m(v) is black holes could further lower this bound to m(v) black holes in the slow-rotation regime, that we developed up to second order in rotation, and that can be extended to other spacetime metrics and other theories.

  9. Growing container seedlings: Three considerations

    Science.gov (United States)

    Kas Dumroese; Thomas D. Landis

    2015-01-01

    The science of growing reforestation and conservation plants in containers has continually evolved, and three simple observations may greatly improve seedling quality. First, retaining stock in its original container for more than one growing season should be avoided. Second, strongly taprooted species now being grown as bareroot stock may be good candidates...

  10. 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.

  11. Measuring Successful Aging in Southern Black Older Adults

    Science.gov (United States)

    Troutman, Meredith; Nies, Mary A.; Bentley, Monica

    2011-01-01

    With the growing size of the population of aging Black individuals, it is important to understand successful aging in this group. This study, therefore, piloted the Successful Aging Inventory (SAI) with a convenience sample of Black older adults. Participants completed a demographic form, the SAI, Purpose in Life Test, Life Satisfaction…

  12. Understanding Afrocentrism: Why Blacks Dream of a World without Whites.

    Science.gov (United States)

    Early, Gerald

    1995-01-01

    Describes the perceived failure of integration and the growing number of black Americans who are looking at the world from an African perspective instead of from the European-centered perspective that dominates American culture. The article explains Afrocentrism's appeal in giving Blacks an ideological unity, not just on color but as an expression…

  13. "If You Only Knew": Lessons Learned from Successful Black Entrepreneurs.

    Science.gov (United States)

    Smith, Cheryl A.

    2001-01-01

    A qualitative study investigated success in entrepreneurship from the standpoint of Black women entrepreneurs, one of the fastest growing groups of new small business owners. It explored the business and learning experiences of successful Black women graduates of an entrepreneurship training program in New York State to identify learning…

  14. Molecular characterization of aphid resistance in black raspberry germplasm

    Science.gov (United States)

    Black raspberry is a minor but lucrative crop with most of the acreage in the U.S. found in Oregon. Rapid decline of plantings results from virus infection vectored by the North American large raspberry aphid and is the most limiting factor for growing black raspberry. Existing cultivars are suscept...

  15. Black Urine

    Directory of Open Access Journals (Sweden)

    Rahim Vakili

    2016-06-01

    Full Text Available A 2-year-old boy was born at term of healthy, non-consanguineous Iranian parents. His mother attended in the clinic with the history of sometimes discoloration of diapers after passing urine. She noticed that first at the age of one month with intensified in recent months. His Physical examination and growth parameters were normal. His mother denied taking any medication (sorbitol, nitrofurantoin, metronidazole, methocarbamol, sena and methyldopa (5. Qualitative urine examination showed dark black discoloration. By this history, alkaptonuria was the most clinical suspicious. A 24-hour-urine sample was collected and sent for quantitative measurements. The urine sample was highly positive for homogentisic acid and negative for porphyrin metabolites.

  16. Massive 2-form field and holographic ferromagnetic phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Rong-Gen; Yang, Run-Qiu [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190 (China); Wu, Ya-Bo; Zhang, Cheng-Yuan [Department of Physics, Liaoning Normal University,Dalian, 116029 (China)

    2015-11-05

    In this paper we investigate in some detail the holographic ferromagnetic phase transition in an AdS{sub 4} black brane background by introducing a massive 2-form field coupled to the Maxwell field strength in the bulk. In two probe limits, one is to neglect the back reaction of the 2-form field to the background geometry and to the Maxwell field, and the other to neglect the back reaction of both the Maxwell field and the 2-form field, we find that the spontaneous magnetization and the ferromagnetic phase transition always happen when the temperature gets low enough with similar critical behavior. We calculate the DC resistivity in a semi-analytical method in the second probe limit and find it behaves as the colossal magnetic resistance effect in some materials. In the case with the first probe limit, we obtain the off-shell free energy of the holographic model near the critical temperature and compare with the Ising-like model. We also study the back reaction effect and find that the phase transition is always second order. In addition, we find an analytical Reissner-Norström-like black brane solution in the Einstein-Maxwell-2-form field theory with a negative cosmological constant.

  17. Massive Open Online Courses: Droom of nachtmerrie?

    NARCIS (Netherlands)

    Rubens, Wilfred

    2014-01-01

    Rubens, W. (2014, 9 april). Massive Open Online Courses: Droom of nachtmerrie? Presentatie tijdens een studiemiddag van iPROFS over innovatieve Liferay-toepassingen voor het onderwijs, Utrecht, Nederland

  18. How I treat patients with massive hemorrhage

    DEFF Research Database (Denmark)

    Johansson, Pär I; Stensballe, Jakob; Oliveri, Roberto

    2014-01-01

    Massive hemorrhage is associated with coagulopathy and high mortality. The transfusion guidelines up to 2006 recommended that resuscitation of massive hemorrhage should occur in successive steps using crystalloids, colloids and red blood cells (RBC) in the early phase, and plasma and platelets...... in the late phase. With the introduction of the cell-based model of hemostasis in the mid 1990ties, our understanding of the hemostatic process and of coagulopathy has improved. This has contributed to a change in resuscitation strategy and transfusion therapy of massive hemorrhage along with an acceptance...... outcome, although final evidence on outcome from randomized controlled trials are lacking. We here present how we in Copenhagen and Houston, today, manage patients with massive hemorrhage....

  19. Thermographic inspection of massive structures

    International Nuclear Information System (INIS)

    Renshaw, Jeremy B.; Guimaraes, Maria; Scott, David B.

    2014-01-01

    Nondestructive Evaluation of concrete structures is a growing concern for the nuclear industry as well as for many other industries. As critical concrete components continue to age, the ability to assess the health and suitability for continued service has become a key consideration. In some cases, repair of these structures is difficult and expensive, while replacement is prohibitively expensive or, in some cases, not feasible. Therefore, the ability to inspect these key assets is a primary concern, especially in the nuclear industry. Due to the large size of containment buildings, cooling towers, and other large concrete assets, the ability to rapidly inspect for defects of concern is very desirable. Thermographic inspection appears to have the required ability to rapidly inspect large structures to ascertain the location and size of many of the defects of concern. This ability was demonstrated by performing a thermographic inspection of a large concrete dam in 2 days

  20. Asymptotically spacelike warped anti-de Sitter spacetimes in generalized minimal massive gravity

    Science.gov (United States)

    Setare, M. R.; Adami, H.

    2017-06-01

    In this paper we show that warped AdS3 black hole spacetime is a solution of the generalized minimal massive gravity (GMMG) and introduce suitable boundary conditions for asymptotically warped AdS3 spacetimes. Then we find the Killing vector fields such that transformations generated by them preserve the considered boundary conditions. We calculate the conserved charges which correspond to the obtained Killing vector fields and show that the algebra of the asymptotic conserved charges is given as the semi direct product of the Virasoro algebra with U(1) current algebra. We use a particular Sugawara construction to reconstruct the conformal algebra. Thus, we are allowed to use the Cardy formula to calculate the entropy of the warped black hole. We demonstrate that the gravitational entropy of the warped black hole exactly coincides with what we obtain via Cardy’s formula. As we expect, the warped Cardy formula also gives us exactly the same result as we obtain from the usual Cardy’s formula. We calculate mass and angular momentum of the warped black hole and then check that obtained mass, angular momentum and entropy to satisfy the first law of the black hole mechanics. According to the results of this paper we believe that the dual theory of the warped AdS3 black hole solution of GMMG is a warped CFT.

  1. Asymptotically spacelike warped anti-de Sitter spacetimes in generalized minimal massive gravity

    International Nuclear Information System (INIS)

    Setare, M R; Adami, H

    2017-01-01

    In this paper we show that warped AdS 3 black hole spacetime is a solution of the generalized minimal massive gravity (GMMG) and introduce suitable boundary conditions for asymptotically warped AdS 3 spacetimes. Then we find the Killing vector fields such that transformations generated by them preserve the considered boundary conditions. We calculate the conserved charges which correspond to the obtained Killing vector fields and show that the algebra of the asymptotic conserved charges is given as the semi direct product of the Virasoro algebra with U (1) current algebra. We use a particular Sugawara construction to reconstruct the conformal algebra. Thus, we are allowed to use the Cardy formula to calculate the entropy of the warped black hole. We demonstrate that the gravitational entropy of the warped black hole exactly coincides with what we obtain via Cardy’s formula. As we expect, the warped Cardy formula also gives us exactly the same result as we obtain from the usual Cardy’s formula. We calculate mass and angular momentum of the warped black hole and then check that obtained mass, angular momentum and entropy to satisfy the first law of the black hole mechanics. According to the results of this paper we believe that the dual theory of the warped AdS 3 black hole solution of GMMG is a warped CFT. (paper)

  2. Black Silicon Solar Cells with Black Ribbons

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

    2016-01-01

    We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies...... in the range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....

  3. Black Silicon Solar Cells with Black Ribbons

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

    2016-01-01

    We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... in the range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies...

  4. The Black Hole Formation Probability

    Science.gov (United States)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  5. THE BLACK HOLE FORMATION PROBABILITY

    International Nuclear Information System (INIS)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH (M ZAMS ). Although we find that it is difficult to derive a unique P BH (M ZAMS ) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH (M ZAMS ) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH (M ZAMS ) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment

  6. How Your Fetus Grows During Pregnancy

    Science.gov (United States)

    ... ACOG Pregnancy Book How Your Fetus Grows During Pregnancy Patient Education FAQs How Your Fetus Grows During Pregnancy Patient Education Pamphlets - Spanish How Your Fetus Grows During Pregnancy ...

  7. Black African Immigrant College Students' Perceptions of Belonging at a Predominately White Institution

    Science.gov (United States)

    Stebleton, Michael J.; Aleixo, Marina B.

    2016-01-01

    A growing number of college-age Blacks in the United States are Black African immigrants. Using a constructivist grounded theory approach, the researchers interviewed 12 undergraduate Black African immigrant college students attending a predominately White institution (PWI) about their experiences and perceptions of belonging. Findings suggest…

  8. Black holes. Chapter 6

    International Nuclear Information System (INIS)

    Penrose, R.

    1980-01-01

    Conditions for the formation of a black hole are considered, and the properties of black holes. The possibility of Cygnus X-1 as a black hole is discussed. Einstein's theory of general relativity in relation to the formation of black holes is discussed. (U.K.)

  9. Black Eye: First Aid

    Science.gov (United States)

    First aid Black eye Black eye: First aid By Mayo Clinic Staff A black eye is caused by bleeding under the skin around the eye. Most injuries that cause a ... 13, 2018 Original article: http://www.mayoclinic.org/first-aid/first-aid-black-eye/basics/ART-20056675 . Mayo ...

  10. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk

    2017-02-01

    Full Text Available We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino emission. Accretion of matter powers the relativistic jets, responsible for the gamma ray prompt emission. The significant number density of neutrons in the disk and outflowing material will cause subsequent formation of heavier nuclei. We study the process of nucleosynthesis and its possible observational consequences. We also apply our scenario to the recent observation of the gravitational wave signal, detected on 14 September 2015 by the two Advanced LIGO detectors, and related to an inspiral and merger of a binary black hole system. A gamma ray burst that could possibly be related with the GW150914 event was observed by the Fermi satellite. It had a duration of about 1 s and appeared about 0.4 s after the gravitational-wave signal. We propose that a collapsing massive star and a black hole in a close binary could lead to the event. The gamma ray burst was powered by a weak neutrino flux produced in the star remnant’s matter. Low spin and kick velocity of the merged black hole are reproduced in our simulations. Coincident gravitational-wave emission originates from the merger of the collapsed core and the companion black hole.

  11. Search for black holes

    International Nuclear Information System (INIS)

    Cherepashchuk, Anatolii M

    2003-01-01

    Methods and results of searching for stellar mass black holes in binary systems and for supermassive black holes in galactic nuclei of different types are described. As of now (June 2002), a total of 100 black hole candidates are known. All the necessary conditions Einstein's General Relativity imposes on the observational properties of black holes are satisfied for candidate objects available, thus further assuring the existence of black holes in the Universe. Prospects for obtaining sufficient criteria for reliably distinguishing candidate black holes from real black holes are discussed. (reviews of topical problems)

  12. REDSHIFT EVOLUTION IN BLACK HOLE-BULGE RELATIONS: TESTING C IV-BASED BLACK HOLE MASSES

    International Nuclear Information System (INIS)

    Greene, Jenny E.; Peng, Chien Y.; Ludwig, Randi R.

    2010-01-01

    We re-examine claims for redshift evolution in black hole-bulge scaling relations based on lensed quasars. In particular, we refine the black hole (BH) mass estimates using measurements of Balmer lines from near-infrared spectroscopy obtained with Triplespec at Apache Point Observatory. In support of previous work, we find a large scatter between Balmer and UV line widths, both Mg IIλλ2796, 2803 and C IVλλ1548, 1550. There is tentative evidence that C III]λ1909, despite being a blend of multiple transitions, may correlate well with Mg II, although a larger sample is needed for a real calibration. Most importantly, we find no systematic changes in the estimated BH masses for the lensed sample based on Balmer lines, providing additional support to the interpretation that black holes were overly massive compared to their host galaxies at high redshift.

  13. High Precision Integrator for Black Hole Dynamics

    Science.gov (United States)

    Löckmann, U.; Baumgardt, H.

    2006-08-01

    Over the last decades, due to increasing performance of computer systems, a large number of highly effective integrators for dynamical systems have been developed for different purposes. Among those are integrators for multi-particle systems such as star clusters (e.g., Aarseth 1999), and for highly accurate long-term integration of planetary systems, where relatively few particles move on nearly circular orbits. However, capabilities of currently available integrators are limited when it comes to multi-particle systems with a massive central particle. In this work, I am investigating integrators combining the advantages of available integrators, such as highly accurate long-term integration of Keplerian orbits and adaptive timesteps allowing for efficient integration of perturbations. This can be useful for fully collisional simulations of stellar systems comprising a massive black hole, e. g. the galactic centre.

  14. Black-hole masses of distant quasars

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2011-01-01

    A brief overview of the methods commonly used to determine or estimate the black hole mass in quiescent or active galaxies is presented and it is argued that the use of mass-scaling relations is both a reliable and the preferred method to apply to large samples of distant quasars. The method uses...... that the black hole masses are very large, of order 1 to 10 billion solar masses, even at the highest redshifts of 4 to 6. The black holes must build up their mass very fast in the early universe. Yet they do not grow much larger than that: a maximum mass of about 10 billion solar masses is also observed....... Preliminary mass functions of active black holes are presented for several quasar samples, including the Sloan Digital Sky Survey. Finally, common concerns related to the application of the mass scaling relations, especially for high redshift quasars, are briefly discussed....

  15. Integrating Building Functions into Massive External Walls

    Directory of Open Access Journals (Sweden)

    Ahmed Hisham Hafez

    2017-11-01

    Full Text Available Well into the twentieth century, brick and stone were the materials used. Bricklaying and stonemasonry were the construction technologies employed for the exterior walls of virtually all major structures. However, with the rise in quality of life, the massive walls alone became incapable of fulfilling all the developed needs. Adjacent systems and layers had then to be attached to the massive layer. Nowadays, the external wall is usually composed of a layered construction. Each external wall function is usually represented by a separate layer or system. The massive layer of the wall is usually responsible for the load-bearing function. Traditional massive external walls vary in terms of their external appearance, their composition and attached layers. However, their design and construction process is usually a repeated process. It is a linear process where each discipline is concerned with a separate layer or system. These disciplines usually take their tasks away and bring them back to be re-integrated in a layered manner. New massive technologies with additional function have recently become available. Such technologies can provide the external wall with other functions in addition to its load-bearing function. The purpose of this research is to map the changes required to the traditional design and construction process when massive technologies with additional function are applied in external walls. Moreover, the research aims at assessing the performance of massive solutions with additional function when compared to traditional solutions in two different contexts, the Netherlands and Egypt. Through the analysis of different additional function technologies in external walls, a guidance scheme for different stakeholders is generated. It shows the expected process changes as related to the product level and customization level. Moreover, the research concludes that the performance of additional insulating technologies, and specifically

  16. Forming spectroscopic massive protobinaries by disc fragmentation

    Science.gov (United States)

    Meyer, D. M.-A.; Kuiper, R.; Kley, W.; Johnston, K. G.; Vorobyov, E.

    2018-01-01

    The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary companions which will later strongly influence the star's future evolution in the Hertzsprung-Russel diagram. We present three-dimensional gravitation-radiation-hydrodynamic numerical simulations of 100 M⊙ pre-stellar cores. We find that accretion discs of young massive stars violently fragment without preventing the (highly variable) accretion of gaseous clumps on to the protostars. While acquiring the characteristics of a nascent low-mass companion, some disc fragments migrate on to the central massive protostar with dynamical properties showing that its final Keplerian orbit is close enough to constitute a close massive protobinary system, having a young high- and a low-mass components. We conclude on the viability of the disc fragmentation channel for the formation of such short-period binaries, and that both processes - close massive binary formation and accretion bursts - may happen at the same time. FU-Orionis-type bursts, such as observed in the young high-mass star S255IR-NIRS3, may not only indicate ongoing disc fragmentation, but also be considered as a tracer for the formation of close massive binaries - progenitors of the subsequent massive spectroscopic binaries - once the high-mass component of the system will enter the main-sequence phase of its evolution. Finally, we investigate the Atacama Large (sub-)Millimeter Array observability of the disc fragments.

  17. Massive relic galaxies prefer dense environments

    Science.gov (United States)

    Peralta de Arriba, Luis; Quilis, Vicent; Trujillo, Ignacio; Cebrián, María; Balcells, Marc

    2016-09-01

    We study the preferred environments of z ∼ 0 massive relic galaxies (M⋆ ≳ 1010 M⊙ galaxies with little or no growth from star formation or mergers since z ∼ 2). Significantly, we carry out our analysis on both a large cosmological simulation and an observed galaxy catalogue. Working on the Millennium I-WMAP7 simulation we show that the fraction of today massive objects which have grown less than 10 per cent in mass since z ∼ 2 is ∼0.04 per cent for the whole massive galaxy population with M⋆ ≳ 1010 M⊙. This fraction rises to ∼0.18 per cent in galaxy clusters, confirming that clusters help massive galaxies remain unaltered. Simulations also show that massive relic galaxies tend to be closer to cluster centres than other massive galaxies. Using the New York University Value-Added Galaxy Catalogue, and defining relics as M⋆ ≳ 1010 M⊙ early-type galaxies with colours compatible with single-stellar population ages older than 10 Gyr, and which occupy the bottom 5-percentile in the stellar mass-size distribution, we find 1.11 ± 0.05 per cent of relics among massive galaxies. This fraction rises to 2.4 ± 0.4 per cent in high-density environments. Our findings point in the same direction as the works by Poggianti et al. and Stringer et al. Our results may reflect the fact that the cores of the clusters are created very early on, hence the centres host the first cluster members. Near the centres, high-velocity dispersions and harassment help cluster core members avoid the growth of an accreted stellar envelope via mergers, while a hot intracluster medium prevents cold gas from reaching the galaxies, inhibiting star formation.

  18. Asymptotic analysis of multicell massive MIMO over Rician fading channels

    KAUST Repository

    Sanguinetti, Luca

    2017-06-20

    This work considers the downlink of a multicell massive MIMO system in which L base stations (BSs) of N antennas each communicate with K single-antenna user equipments randomly positioned in the coverage area. Within this setting, we are interested in evaluating the sum rate of the system when MRT and RZF are employed under the assumption that each intracell link forms a MIMO Rician uncorrelated fading channel. The analysis is conducted assuming that N and K grow large with a non-trivial ratio N/K under the assumption that the data transmission in each cell is affected by channel estimation errors, pilot contamination, and an arbitrary large scale attenuation. Numerical results are used to validate the asymptotic analysis in the finite system regime and to evaluate the network performance under different settings. The asymptotic results are also instrumental to get insights into the interplay among system parameters.

  19. Black hole based tests of general relativity

    International Nuclear Information System (INIS)

    Yagi, Kent; Stein, Leo C

    2016-01-01

    General relativity has passed all solar system experiments and neutron star based tests, such as binary pulsar observations, with flying colors. A more exotic arena for testing general relativity is in systems that contain one or more black holes. Black holes are the most compact objects in the Universe, providing probes of the strongest-possible gravitational fields. We are motivated to study strong-field gravity since many theories give large deviations from general relativity only at large field strengths, while recovering the weak-field behavior. In this article, we review how one can probe general relativity and various alternative theories of gravity by using electromagnetic waves from a black hole with an accretion disk, and gravitational waves from black hole binaries. We first review model-independent ways of testing gravity with electromagnetic/gravitational waves from a black hole system. We then focus on selected examples of theories that extend general relativity in rather simple ways. Some important characteristics of general relativity include (but are not limited to) (i) only tensor gravitational degrees of freedom, (ii) the graviton is massless, (iii) no quadratic or higher curvatures in the action, and (iv) the theory is four-dimensional. Altering a characteristic leads to a different extension of general relativity: (i) scalar–tensor theories, (ii) massive gravity theories, (iii) quadratic gravity, and (iv) theories with large extra dimensions. Within each theory, we describe black hole solutions, their properties, and current and projected constraints on each theory using black hole based tests of gravity. We close this review by listing some of the open problems in model-independent tests and within each specific theory. (paper)

  20. The Massive Star Population in M101

    Science.gov (United States)

    Grammer, Skyler; Humphreys, R. M.

    2013-06-01

    Evolved massive stars including luminous blue variables and hypergiants are the likely progenitor class of giant eruptions or supernova impostors (SN impostors). Motivated by the small number of progenitors positively associated with SN impostors, we present a survey of the massive star population in M101. Regions of massive star formation, ranging from 0.05 kpc2 to 50 kpc2, were identified using GALEX FUV and NUV imaging across the face of M101. The resolved stellar populations within each region were extracted from sixteen archival multicolor HST ACS WFC observations and color-magnitude-diagrams (CMD) were created. We have identified red supergiant (RSG) and blue supergiant (BSG) candidates using color and luminosity criteria. The RSG and BSG candidates identified represents the population of stars in M101 likely to be the SN impostor progenitor class. Furthermore we have determined the star formation histories (SFH) for the massive star populations within each region using two methods: CMD modeling, and spectral-energy-distribution fitting. We find that there has been a continuous buildup of massive stars over the last 100 Myr with a sharp increase in star formation rate within the last 20 Myr. Evidence for a decrease in mean stellar ages for regions with increasing radii has also been observed and is consistent with previously observed color gradients in optical and UV.

  1. Black yeast-like fungi in skin and nail

    DEFF Research Database (Denmark)

    Saunte, D M; Tarazooie, B; Arendrup, M C

    2011-01-01

    the probability of these species to be involved in disease. Slow-growing black yeast-like fungi in routine specimens were prospectively collected and identified. A questionnaire regarding patient information was sent to physicians regarding black yeast-like fungus positive patients. A total of 20 746...... dermatological specimens were examined by culture. Black yeast-like fungi accounted for 2.2% (n = 108) of the positive cultures. Only 31.0% of the samples, culture positive for black yeast-like fungi were direct microscopy positive when compared with overall 68.8% of the culture positive specimens. The most...

  2. CAUGHT IN THE ACT: THE ASSEMBLY OF MASSIVE CLUSTER GALAXIES AT z = 1.62

    International Nuclear Information System (INIS)

    Lotz, Jennifer M.; Ferguson, Henry C.; Grogin, Norman; Koekemoer, Anton M.; Papovich, Casey; Tran, Kim-Vy; Faber, S. M.; Guo Yicheng; Kocevski, Dale; Lee, Kyoung-Soo; McIntosh, Daniel; Momcheva, Ivelina; Rudnick, Gregory; Saintonge, Amelie; Van der Wel, Arjen; Willmer, Christopher

    2013-01-01

    We present the recent merger history of massive galaxies in a spectroscopically confirmed proto-cluster at z = 1.62. Using Hubble Space Telescope WFC3 near-infrared imaging from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we select cluster and z ∼ 1.6 field galaxies with M star ≥ 3 × 10 10 M ☉ , to determine the frequency of double nuclei or close companions within projected separations less than 20 kpc co-moving. We find that four out of five spectroscopically confirmed massive proto-cluster galaxies have double nuclei, and 57 +13 -14 % of all M star ≥ 3 × 10 10 M ☉ cluster candidates are observed in either close pair systems or have double nuclei. In contrast, only 11% ± 3% of the field galaxies are observed in close pair/double nuclei systems. After correcting for the contribution from random projections, the implied merger rate per massive galaxy in the proto-cluster is ∼3-10 times higher than the merger rate of massive field galaxies at z ∼ 1.6. Close pairs in the cluster have minor merger stellar mass ratios (M primary : M satellite ≥ 4), while the field pairs consist of both major and minor mergers. At least half of the cluster mergers are gas-poor, as indicated by their red colors and low 24 μm fluxes. Two of the double-nucleated cluster members have X-ray detected active galactic nuclei with L x > 10 43 erg s –1 , and are strong candidates for dual or offset super-massive black holes. We conclude that the massive z = 1.62 proto-cluster galaxies are undergoing accelerated assembly via minor mergers, and discuss the implications for galaxy evolution in proto-cluster environments

  3. The Stripe 82 Massive Galaxy Project. III. A Lack of Growth among Massive Galaxies

    Science.gov (United States)

    Bundy, Kevin; Leauthaud, Alexie; Saito, Shun; Maraston, Claudia; Wake, David A.; Thomas, Daniel

    2017-12-01

    The average stellar mass (M *) of high-mass galaxies ({log}{M}* /{M}⊙ > 11.5) is expected to grow by ˜30% since z˜ 1, largely through ongoing mergers that are also invoked to explain the observed increase in galaxy sizes. Direct evidence for the corresponding growth in stellar mass has been elusive, however, in part because the volumes sampled by previous redshift surveys have been too small to yield reliable statistics. In this work, we make use of the Stripe 82 Massive Galaxy Catalog (S82-MGC) to build a mass-limited sample of 41,770 galaxies ({log}{M}* /{M}⊙ > 11.2) with optical-to-near-IR photometry and a large fraction (>55%) of spectroscopic redshifts. Our sample spans 139 deg2, significantly larger than most previous efforts. After accounting for a number of potential systematic errors, including the effects of M * scatter, we measure galaxy stellar mass functions over 0.3history assumed for M * estimates, although our inability to characterize low-surface-brightness outskirts may be the most important limitation of our study. Even among these high-mass galaxies, we find evidence for differential evolution when splitting the sample by recent SF activity. While low-SF systems appear to become completely passive, we find a mostly subdominant population of galaxies with residual, but low rates of SF (˜1 M ⊙ yr-1) whose number density does not evolve. Interestingly, these galaxies become more prominent at higher M *, representing ˜10% of all galaxies at {10}12 {M}⊙ and perhaps dominating at even larger masses.

  4. Black and white homebuyer, homeowner, and household segregation in the United States, 1990-2010.

    Science.gov (United States)

    Fischer, Mary J

    2013-11-01

    As homeownership has been expanding in the United States over the past several decades, residential segregation between blacks and whites has been declining in most metropolitan areas. However, the degree to which the residential patterns of new homebuyers have mirrored these overall trends in segregation and how the massive increase in home buying has related to changes in segregation has remained largely unexplored. This paper examines the segregation of new black homebuyers from white households, new white homebuyers from black households, and black and white households from each other using Home Mortgage Disclosure Act (HMDA) data from 1992 to 2010 merged with data from the Census and ACS. I find that black homebuyers are less segregated from white households than black homeowners overall and black households in general, providing evidence in support of the spatial assimilation model that would predict better outcomes for homeowners. Also consistent with the spatial assimilation perspective, I found in the multivariate models that increased income parity between blacks and whites and growth in black lending are associated with average declines in black/white household segregation from 1990 to 2010. Although subprime lending was not associated with overall changes in segregation, metropolitan areas with higher percentages of loans to blacks from subprime lenders experienced increases in segregation of both black homeowners from white households as well as white owners from black households. Copyright © 2013. Published by Elsevier Inc.

  5. Growing Oppression, Growing Resistance : LGBT Activism and Europeanisation in Macedonia

    NARCIS (Netherlands)

    Miškovska Kajevska, A.; Bilić, B.

    2016-01-01

    This chapter provides one of the first socio-historical overviews of the LGBT groups in Macedonia and argues that an important impetus for the proliferation of LGBT activities has been the growing state-endorsed homophobia starting from 2008. The homophobic rhetoric of the ruling parties was clearly

  6. Dynamics of black holes in galactic centres.

    Science.gov (United States)

    Hemsendorf, M.

    The dynamics of a massive binary system in a galactic nucleus are presented. These are the first results from simulations applying a hybrid "self consistent field" (SCF) and direct Aarseth N-body integrator (NBODY6), which synthesises the advantages of the direct force calculation with the efficiency of the field method. The code is aimed for use on parallel architectures and is therefore applicable for collisional N-body integrations with extraordinarily large particle numbers (>105). It opens the perspective to simulate the dynamics of globular clusters with realistic collisional relaxation, as well as stellar systems surrounding a supermassive black hole in galactic nuclei.

  7. Brane world black rings

    International Nuclear Information System (INIS)

    Sahay, Anurag; Sengupta, Gautam

    2007-01-01

    Five dimensional neutral rotating black rings are described from a Randall-Sundrum brane world perspective in the bulk black string framework. To this end we consider a rotating black string extension of a five dimensional black ring into the bulk of a six dimensional Randall-Sundrum brane world with a single four brane. The bulk solution intercepts the four brane in a five dimensional black ring with the usual curvature singularity on the brane. The bulk geodesics restricted to the plane of rotation of the black ring are constructed and their projections on the four brane match with the usual black ring geodesics restricted to the same plane. The asymptotic nature of the bulk geodesics are elucidated with reference to a bulk singularity at the AdS horizon. We further discuss the description of a brane world black ring as a limit of a boosted bulk black 2 brane with periodic identification

  8. Massive type IIA supergravity and E10

    International Nuclear Information System (INIS)

    Henneaux, M.; Kleinschmidt, A.; Persson, D.; Jamsin, E.

    2009-01-01

    In this talk we investigate the symmetry under E 10 of Romans' massive type IIA supergravity. We show that the dynamics of a spinning particle in a non-linear sigma model on the coset space E 10 /K(E 10 ) reproduces the bosonic and fermionic dynamics of massive IIA supergravity, in the standard truncation. In particular, we identify Romans' mass with a generator of E 10 that is beyond the realm of the generators of E 10 considered in the eleven-dimensional analysis, but using the same, underformed sigma model. As a consequence, this work provides a dynamical unification of the massless and massive versions of type IIA supergravity inside E 10 . (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  9. HOW TO FIND YOUNG MASSIVE CLUSTER PROGENITORS

    Energy Technology Data Exchange (ETDEWEB)

    Bressert, E.; Longmore, S.; Testi, L. [European Southern Observatory, Karl Schwarzschild Str. 2, D-85748 Garching bei Muenchen (Germany); Ginsburg, A.; Bally, J.; Battersby, C. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States)

    2012-10-20

    We propose that bound, young massive stellar clusters form from dense clouds that have escape speeds greater than the sound speed in photo-ionized gas. In these clumps, radiative feedback in the form of gas ionization is bottled up, enabling star formation to proceed to sufficiently high efficiency so that the resulting star cluster remains bound even after gas removal. We estimate the observable properties of the massive proto-clusters (MPCs) for existing Galactic plane surveys and suggest how they may be sought in recent and upcoming extragalactic observations. These surveys will potentially provide a significant sample of MPC candidates that will allow us to better understand extreme star-formation and massive cluster formation in the Local Universe.

  10. Massive stars and X-ray pulsars

    International Nuclear Information System (INIS)

    Henrichs, H.

    1982-01-01

    This thesis is a collection of 7 separate articles entitled: long term changes in ultraviolet lines in γ CAS, UV observations of γ CAS: intermittent mass-loss enhancement, episodic mass loss in γ CAS and in other early-type stars, spin-up and spin-down of accreting neutron stars, an excentric close binary model for the X Persei system, has a 97 minute periodicity in 4U 1700-37/HD 153919 really been discovered, and, mass loss and stellar wind in massive X-ray binaries. (Articles 1, 2, 5, 6 and 7 have been previously published). The first three articles are concerned with the irregular mass loss in massive stars. The fourth critically reviews thoughts since 1972 on the origin of the changes in periodicity shown by X-ray pulsars. The last articles indicate the relation between massive stars and X-ray pulsars. (C.F.)

  11. Critical N = (1, 1) general massive supergravity

    Science.gov (United States)

    Deger, Nihat Sadik; Moutsopoulos, George; Rosseel, Jan

    2018-04-01

    In this paper we study the supermultiplet structure of N = (1, 1) General Massive Supergravity at non-critical and critical points of its parameter space. To do this, we first linearize the theory around its maximally supersymmetric AdS3 vacuum and obtain the full linearized Lagrangian including fermionic terms. At generic values, linearized modes can be organized as two massless and 2 massive multiplets where supersymmetry relates them in the standard way. At critical points logarithmic modes appear and we find that in three of such points some of the supersymmetry transformations are non-invertible in logarithmic multiplets. However, in the fourth critical point, there is a massive logarithmic multiplet with invertible supersymmetry transformations.

  12. Exploring the experiences of instructors teaching massive open online courses in tourism and hospitality: a mixed methods approach

    OpenAIRE

    Lin, Jingjing; Cantoni, Lorenzo

    2018-01-01

    Massive Open Online Courses (MOOCs) have existed as a disruptive educational phenomenon for nine years. Grounded in the roots of distance education, open education, Open Educational Resources, and OpenCourseWare, MOOCs have now survived various critics and have continued growing globally. Reports about MOOCs in both the press and scholarly publications began to grow significantly in 2013 (Sánchez-Vera, Leon Urrutia, & Davis, 2015; Zancanaro & Domingues, 2017) and, since then, more and mo...

  13. Growth of Appalachian hardwoods kept free to grow from 2 to 12 years after clearcutting

    Science.gov (United States)

    H. Clay Smith

    1983-01-01

    Free-to-grow sapling-size, yellow-poplars of seedling origin outgrew similar black cherry and red oak in both dbh and total height (especially on good sites). Yellow-poplar consistently grew faster in dbh throughout the study, particularly on the better oak sites. Black cherry had an edge over yellow-poplar in total height during the early years of the study, but...

  14. Cheap heat grows in fields

    International Nuclear Information System (INIS)

    Haluza, I.

    2006-01-01

    Slovak farmers resemble the peasants from the film T he Magnificent Seven . They keep complaining about their fate but consider any innovation as an interference. And that is why they still have not started growing fast-growing wood although the number of heating plants processing bio-mass from forests and fields is growing. Natural gas is expensive and coal creates pollution. Energy from biomass is becoming a good business and also creates new business opportunities - growing the raw material it needs. Such heating plants usually use waste from wood processing companies and Slovak Forests (Lesy SR) has also started deliveries of chip wood from old forests. There are plantations of fast growing wood suitable for heat production of over 500-thousand hectares throughout the EU. This is about 10% of Slovakian's area where the first plantations are also already being set up. The first promising plantation project was launched this spring. And this is not a project launched and backed by a big company but a starting up businessman, Miroslav Forgac from Kosice. He founded his company, Forgim, last winter. Without big money involved and thank to a new business idea he managed to persuade farmers to set up the first plantations. He supplied the seedlings and the business has started with 75 ha of plantations around Trnava, Sala, Komarno, Lucenec, Poprad and Kosice. He is gradually signing contracts with other landowners and next year the area of plantations is set to grow by 1500 ha. Plantations of fast growing trees such as willow, poplar and acacia regenerate by new trees growing out of the roots of the old and from cut trees so from one seedling and one investment there can be several harvests. Swedish willows from Forgim regenerate 20 to 25 years after the first planting. And only then new seedlings have to be purchased. Using special machines that even cut the wood to wood chips the plantations can be 'harvested' every three years. Unlike crops, the fields do not

  15. Crucible Grows Wide Silicon Ribbon

    Science.gov (United States)

    Seidensticker, R.

    1982-01-01

    Inexpensive manufacture of solar cells may require quality silicon ribbon crystals. One way to produce them is by growing wide dendritic webs, which can be very long and have high structural perfection. Dendrites grow from supercooled melt, so width of ribbon depends on how wide a region of supercooled molten silicon can be maintained in crucible. Elongated geometry of suscepter/crucible/lid assembly allows molten silicon to supercool over a wider region -- a necessary condition for the growth of wide dendritic crystal ribbon.

  16. Massive Open Online Courses (MOOCS): Emerging Trends in Assessment and Accreditation

    OpenAIRE

    Chauhan, Amit

    2014-01-01

    In 2014, Massive Open Online Courses (MOOCs) are expected to witness a phenomenal growth in student registration compared to the previous years (Lee, Stewart, & Claugar-Pop, 2014). As MOOCs continue to grow in number, there has been an increasing focus on assessment and evaluation. Because of the huge enrollments in a MOOC, it is impossible for the instructor to grade homework and evaluate each student. The enormous data generated by learners in a MOOC can be used for developing and refining ...

  17. Massive Open Online Courses (MOOCS): Emerging Trends in Assessment and Accreditation.

    OpenAIRE

    Chauhan, Amit

    2014-01-01

    In 2014, Massive Open Online Courses (MOOCs) are expected to witness a phenomenal growth in student registration compared to the previous years. As MOOCs continue to grow in number, there has been an increasing focus on assessment and evaluation. Because of the huge enrollments in a MOOC, it is impossible for the instructor to grade homework and evaluate each student. The enormous data generated by learners in a MOOC can be used for developing and refining automated assessment techniques. ...

  18. Retrograde pulmonary embolectomy in massive pulmonary embolism.

    Science.gov (United States)

    Zarrabi, Khalil; Yarmohammadi, Hooman; Ostovan, Mohammad Ali

    2005-12-01

    The purpose of this study was introduction and evaluation of efficacy and safety of retrograde thromboembolectomy in acute massive pulmonary emboli. The method is described in a 56-year-old woman with acute massive pulmonary thromboemboli. Postoperative course was uneventful. The described surgical technique is not a panacea and definitely not the whole answer, but is a big part of the solution and may be accompanied with less adverse effects. Additionally, there is a need of being reviewed further in large experimental studies and measurements before it could be used safely as a new technique.

  19. Massive pleural effusions in cryptococcal meningitis

    Science.gov (United States)

    Wong, C; Lim, K; Liam, C

    1999-01-01

    Cryptococcal infection uncommonly presents with pulmonary manifestations and even more rarely so as massive bilateral effusions. Pleural involvement is usually associated with underlying pulmonary parenchymal lesions and is unusual while on antifungal therapy. We report a patient with cryptococcal meningitis who, while on intravenous 5-flucytosine and amphotericin B, developed life-threatening bilateral massive pleural effusions with evidence of spontaneous resolution, consistent with prior hypothesis of antigenic stimulation as the cause of pleural involvement.


Keywords: cryptococcosis; pleural effusions PMID:10533638

  20. CSW rules for a massive scalar

    DEFF Research Database (Denmark)

    Boels, Rutger Herman; Schwinn, Christian

    2008-01-01

    We derive the analog of the Cachazo-Svrcek-Witten (CSW) diagrammatic Feynman rules for four-dimensional Yang-Mills gauge theory coupled to a massive colored scalar. The mass term is shown to give rise to a new tower of vertices in addition to the CSW vertices for massless scalars in non-supersymm......We derive the analog of the Cachazo-Svrcek-Witten (CSW) diagrammatic Feynman rules for four-dimensional Yang-Mills gauge theory coupled to a massive colored scalar. The mass term is shown to give rise to a new tower of vertices in addition to the CSW vertices for massless scalars in non...

  1. NON-AQUEOUS DISSOLUTION OF MASSIVE PLUTONIUM

    Science.gov (United States)

    Reavis, J.G.; Leary, J.A.; Walsh, K.A.

    1959-05-12

    A method is presented for obtaining non-aqueous solutions or plutonium from massive forms of the metal. In the present invention massive plutonium is added to a salt melt consisting of 10 to 40 weight per cent of sodium chloride and the balance zinc chloride. The plutonium reacts at about 800 deg C with the zinc chloride to form a salt bath of plutonium trichloride, sodium chloride, and metallic zinc. The zinc is separated from the salt melt by forcing the molten mixture through a Pyrex filter.

  2. Massive gravity and Fierz-Pauli theory

    Energy Technology Data Exchange (ETDEWEB)

    Blasi, Alberto [Universita di Genova, Dipartimento di Fisica, Genova (Italy); Maggiore, Nicola [I.N.F.N.-Sezione di Genova, Genoa (Italy)

    2017-09-15

    Linearized gravity is considered as an ordinary gauge field theory. This implies the need for gauge fixing in order to have well-defined propagators. Only after having achieved this, the most general mass term is added. The aim of this paper is to study of the degrees of freedom of the gauge fixed theory of linearized gravity with mass term. The main result is that, even outside the usual Fierz-Pauli constraint on the mass term, it is possible to choose a gauge fixing belonging to the Landau class, which leads to a massive theory of gravity with the five degrees of freedom of a spin-2 massive particle. (orig.)

  3. Massive intracerebral hemorrhage associated with Wegener granulomatosis.

    Science.gov (United States)

    Ceri, Mevlut; Ortabozkoyun, Levent; Unverdi, Selman; Kirac, Mustafa; Duranay, Murat

    2012-06-01

    Wegener granulomatosis (WG) is a necrotizing granulomatous vasculitis that predominantly affects airways and kidneys. But central nervous system involvement (7-11%) is an uncommon. Massive ICH may occur in the course of WG, and this serious condition is related with high risk of mortality. Therefore, the new treatment strategies may be considered in addition to classical practices in serious organ involvement and recurrent attack. Here, we present an adult patient with WG whose disease was complicated by a massive intracerebral hemorrhage (ICH), which subsequently led to death.

  4. Massive gravity and Fierz-Pauli theory

    International Nuclear Information System (INIS)

    Blasi, Alberto; Maggiore, Nicola

    2017-01-01

    Linearized gravity is considered as an ordinary gauge field theory. This implies the need for gauge fixing in order to have well-defined propagators. Only after having achieved this, the most general mass term is added. The aim of this paper is to study of the degrees of freedom of the gauge fixed theory of linearized gravity with mass term. The main result is that, even outside the usual Fierz-Pauli constraint on the mass term, it is possible to choose a gauge fixing belonging to the Landau class, which leads to a massive theory of gravity with the five degrees of freedom of a spin-2 massive particle. (orig.)

  5. A Massively Parallel Face Recognition System

    Directory of Open Access Journals (Sweden)

    Ari Paasio

    2006-12-01

    Full Text Available We present methods for processing the LBPs (local binary patterns with a massively parallel hardware, especially with CNN-UM (cellular nonlinear network-universal machine. In particular, we present a framework for implementing a massively parallel face recognition system, including a dedicated highly accurate algorithm suitable for various types of platforms (e.g., CNN-UM and digital FPGA. We study in detail a dedicated mixed-mode implementation of the algorithm and estimate its implementation cost in the view of its performance and accuracy restrictions.

  6. A Massively Parallel Face Recognition System

    Directory of Open Access Journals (Sweden)

    Lahdenoja Olli

    2007-01-01

    Full Text Available We present methods for processing the LBPs (local binary patterns with a massively parallel hardware, especially with CNN-UM (cellular nonlinear network-universal machine. In particular, we present a framework for implementing a massively parallel face recognition system, including a dedicated highly accurate algorithm suitable for various types of platforms (e.g., CNN-UM and digital FPGA. We study in detail a dedicated mixed-mode implementation of the algorithm and estimate its implementation cost in the view of its performance and accuracy restrictions.

  7. Semiclassical geons as solitonic black hole remnants

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Francisco S.N. [Centro de Astronomia e Astrofísica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisboa (Portugal); Olmo, Gonzalo J.; Rubiera-Garcia, D., E-mail: flobo@cii.fc.ul.pt, E-mail: gonzalo.olmo@csic.es, E-mail: drubiera@fisica.ufpb.br2 [Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia - CSIC. Universidad de Valencia, Burjassot-46100, Valencia (Spain)

    2013-07-01

    We find that the end state of black hole evaporation could be represented by non-singular and without event horizon stable solitonic remnants with masses of the order the Planck scale and up to ∼ 16 units of charge. Though these objects are locally indistinguishable from spherically symmetric, massive electric (or magnetic) charges, they turn out to be sourceless geons containing a wormhole generated by the electromagnetic field. Our results are obtained by interpreting semiclassical corrections to Einstein's theory in the first-order (Palatini) formalism, which yields second-order equations and avoids the instabilities of the usual (metric) formulation of quadratic gravity. We also discuss the potential relevance of these solutions for primordial black holes and the dark matter problem.

  8. Black Hole Hunters Set New Distance Record

    Science.gov (United States)

    2010-01-01

    Astronomers using ESO's Very Large Telescope have detected, in another galaxy, a stellar-mass black hole much farther away than any other previously known. With a mass above fifteen times that of the Sun, this is also the second most massive stellar-mass black hole ever found. It is entwined with a star that will soon become a black hole itself. The stellar-mass black holes [1] found in the Milky Way weigh up to ten times the mass of the Sun and are certainly not be taken lightly, but, outside our own galaxy, they may just be minor-league players, since astronomers have found another black hole with a mass over fifteen times the mass of the Sun. This is one of only three such objects found so far. The newly announced black hole lies in a spiral galaxy called NGC 300, six million light-years from Earth. "This is the most distant stellar-mass black hole ever weighed, and it's the first one we've seen outside our own galactic neighbourhood, the Local Group," says Paul Crowther, Professor of Astrophysics at the University of Sheffield and lead author of the paper reporting the study. The black hole's curious partner is a Wolf-Rayet star, which also has a mass of about twenty times as much as the Sun. Wolf-Rayet stars are near the end of their lives and expel most of their outer layers into their surroundings before exploding as supernovae, with their cores imploding to form black holes. In 2007, an X-ray instrument aboard NASA's Swift observatory scrutinised the surroundings of the brightest X-ray source in NGC 300 discovered earlier with the European Space Agency's XMM-Newton X-ray observatory. "We recorded periodic, extremely intense X-ray emission, a clue that a black hole might be lurking in the area," explains team member Stefania Carpano from ESA. Thanks to new observations performed with the FORS2 instrument mounted on ESO's Very Large Telescope, astronomers have confirmed their earlier hunch. The new data show that the black hole and the Wolf-Rayet star dance

  9. [The black widow spider--its appearance and control].

    Science.gov (United States)

    Landeka, Nediljko; Plenković, Jasminka

    2003-03-01

    Between 1995 and 2002, a massive appearance of black widow (Latrodectus mactans tredecimguttatus, Rossi 1790) was recorded along the Croatia coast. This paper gives a historical review of latrodectism and observations from Istria and Dalmatia, paying particular attention to the spider's habitat. There are several reasons for the black widow to appear in a new habitat such as the introduction of leguminous plants, watermelons and melons where crops were grown earlier. Black widow can also be found near buildings and gardens. Human contacts with the spider are usually without consequences for humans, thanks to education and a relatively good visibility of the spider. The authors describe their experience in fighting black widow and emphasise the importance of education in preventing lactrodectism.

  10. Bose-Einstein condensates in charged black-hole spacetimes

    Science.gov (United States)

    Castellanos, Elías; Degollado, Juan Carlos; Lämmerzahl, Claus; Macías, Alfredo; Perlick, Volker

    2018-01-01

    We analyze Bose-Einstein condensates on three types of spherically symmetric and static charged black-hole spacetimes: the Reissner-Nordström spacetime, Hoffmann's Born-Infeld black-hole spacetime, and the regular Ayón-Beato-García spacetime. The Bose-Einstein condensate is modeled in terms of a massive scalar field that satisfies a Klein-Gordon equation with a self-interaction term. The scalar field is assumed to be uncharged and not self-gravitating. If the mass parameter of the scalar field is chosen sufficiently small, there are quasi-bound states of the scalar field that may be interpreted as dark matter clouds. We estimate the size and the total energy of such clouds around charged supermassive black holes and we investigate if their observable features can be used for discriminating between the different types of charged black holes.

  11. Noncommutative geometry inspired black holes in Rastall gravity

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Meng-Sen [Shanxi Datong University, Institute of Theoretical Physics, Datong (China); Shanxi Datong University, Department of Physics, Datong (China); Zhao, Ren [Shanxi Datong University, Institute of Theoretical Physics, Datong (China)

    2017-09-15

    Under two different metric ansatzes, the noncommutative geometry inspired black holes (NCBH) in the framework of Rastall gravity are derived and analyzed. We consider the fluid-type matter with the Gaussian-distribution smeared mass density. Taking a Schwarzschild-like metric ansatz, it is shown that the noncommutative geometry inspired Schwarzschild black hole (NCSBH) in Rastall gravity, unlike its counterpart in general relativity (GR), is not a regular black hole. It has at most one event horizon. After showing a finite maximal temperature, the black hole will leave behind a point-like massive remnant at zero temperature. Considering a more general metric ansatz and a special equation of state of the matter, we also find a regular NCBH in Rastall gravity, which has a similar geometric structure and temperature to that of NCSBH in GR. (orig.)

  12. Reconceptualizing successful aging among black women and the relevance of the strong black woman archetype.

    Science.gov (United States)

    Baker, Tamara A; Buchanan, NiCole T; Mingo, Chivon A; Roker, Rosalyn; Brown, Candace S

    2015-02-01

    Although there are multiple pathways to successful aging, little is known of what it means to age successfully among black women. There is a growing body of literature suggesting that black women experience a number of social challenges (sexism and racism) that may present as barriers to aging successfully. Applying aspects of the Strong Black Women ideal, into theoretical concepts of successful aging, may be particularly relevant in understanding which factors impair or promote the ability of black women to age successfully. The Strong Black Women archetype is a culturally salient ideal prescribing that black women render a guise of self-reliance, selflessness, and psychological, emotional, and physical strength. Although this ideal has received considerable attention in the behavioral sciences, it has been largely absent within the gerontology field. Nevertheless, understanding the dynamics of this cultural ideal may enhance our knowledge while developing an appreciation of the black woman's ability to age successfully. Rather than summarize the social, physical, and mental health literature focusing on health outcomes of black women, this conceptual review examines the Strong Black Women archetype and its application to the lived experiences of black women and contributions to current theories of successful aging. Focusing on successful aging exclusively among black women enhances our understanding of this group by considering their identity as women of color while recognizing factors that dictate their ability to age successfully. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Exact Solutions in Modified Massive Gravity and Off-Diagonal Wormhole Deformations

    CERN Document Server

    Vacaru, Sergiu I

    2014-01-01

    There are explored off-diagonal deformations of "prime" metrics in Einstein gravity (for instance, for wormhole configurations) into "target" exact solutions in f(R,T)-modified and massive/ bi-metric gravity theories. The new classes of solutions may posses, or not, Killing symmetries and can be characterized by effective induced masses, anisotropic polarized interactions and cosmological constants. For nonholonomic deformations with (conformal) ellipsoid/ toroid and/or solitonic symmetries and, in particular, for small eccentricity rotoid configurations, we can generate wormholes like objects matching external black ellipsoid - de Sitter geometries. We conclude that there are nonholonomic transforms and/or non-trivial limits to exact solutions in general relativity when modified/ massive gravity effects are modeled by off-diagonal and/or nonholonomic parametric interactions.

  14. Exact solutions in modified massive gravity and off-diagonal wormhole deformations

    Energy Technology Data Exchange (ETDEWEB)

    Vacaru, Sergiu I. [Alexandru Ioan Cuza University, Rector' s Office, Iasi (Romania); CERN, Theory Division, Geneva 23 (Switzerland)

    2014-03-15

    We explore off-diagonal deformations of 'prime' metrics in Einstein gravity (for instance, for wormhole configurations) into 'target' exact solutions in f(R,T)-modified and massive/bi-metric gravity theories. The new classes of solutions may, or may not, possess Killing symmetries and can be characterized by effective induced masses, anisotropic polarized interactions, and cosmological constants. For nonholonomic deformations with (conformal) ellipsoid/ toroid and/or solitonic symmetries and, in particular, for small eccentricity rotoid configurations, we can generate wormhole-like objects matching an external black ellipsoid--de Sitter geometries. We conclude that there are nonholonomic transforms and/or non-trivial limits to exact solutions in general relativity when modified/massive gravity effects are modeled by off-diagonal and/or nonholonomic parametric interactions. (orig.)

  15. 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.

  16. Inferences from growing trees backwards

    Science.gov (United States)

    David W. Green; Kent A. McDonald

    1997-01-01

    The objective of this paper is to illustrate how longitudinal stress wave techniques can be useful in tracking the future quality of a growing tree. Monitoring the quality of selected trees in a plantation forest could provide early input to decisions on the effectiveness of management practices, or future utilization options, for trees in a plantation. There will...

  17. Growing an Emerging Research University

    Science.gov (United States)

    Birx, Donald L.; Anderson-Fletcher, Elizabeth; Whitney, Elizabeth

    2013-01-01

    The emerging research college or university is one of the most formidable resources a region has to reinvent and grow its economy. This paper is the first of two that outlines a process of building research universities that enhance regional technology development and facilitate flexible networks of collaboration and resource sharing. Although the…

  18. Thallium toxicity: A growing concern

    OpenAIRE

    Saha A

    2005-01-01

    This review article deals with the growing concern of the toxicity of thallium. This article describes the characteristics of thallium, its potential sources of exposure, kinetics, and toxicity on human being and diagnosis of thallium poisoning. This article also describes some episodes of thallium poisoning arising from both occupational and nonoccupational exposure.

  19. Organization of growing random networks

    Energy Technology Data Exchange (ETDEWEB)

    Krapivsky, P. L.; Redner, S.

    2001-06-01

    The organizational development of growing random networks is investigated. These growing networks are built by adding nodes successively, and linking each to an earlier node of degree k with an attachment probability A{sub k}. When A{sub k} grows more slowly than linearly with k, the number of nodes with k links, N{sub k}(t), decays faster than a power law in k, while for A{sub k} growing faster than linearly in k, a single node emerges which connects to nearly all other nodes. When A{sub k} is asymptotically linear, N{sub k}(t){similar_to}tk{sup {minus}{nu}}, with {nu} dependent on details of the attachment probability, but in the range 2{lt}{nu}{lt}{infinity}. The combined age and degree distribution of nodes shows that old nodes typically have a large degree. There is also a significant correlation in the degrees of neighboring nodes, so that nodes of similar degree are more likely to be connected. The size distributions of the in and out components of the network with respect to a given node{emdash}namely, its {open_quotes}descendants{close_quotes} and {open_quotes}ancestors{close_quotes}{emdash}are also determined. The in component exhibits a robust s{sup {minus}2} power-law tail, where s is the component size. The out component has a typical size of order lnt, and it provides basic insights into the genealogy of the network.

  20. Heat stress in growing pigs

    NARCIS (Netherlands)

    Huynh Thi Thanh Thuy,

    2005-01-01

    Compared to other species of farm animals, pigs are more sensitive to high environmental temperatures, because they cannot sweat and do not pant so well. Furthermore, fast-growing lean pigs generate more heat than their congeners living in the wild. This, in combination with confined housing, makes