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Sample records for agn luminosity function

  1. Clustering, Cosmology and a New Era of Black Hole Demographics: The Conditional Luminosity Function of AGNs

    Science.gov (United States)

    Ballantyne, David R.

    2016-04-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of AGN evolution stretching back to z˜5. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, we present a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific z. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function - all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method is demonstrated at z ≈0 and 0.9, and clear luminosity dependence in the AGN bias and mean halo mass is predicted at both z. The results support the idea that there are at least two different modes of AGN triggering: one, at high luminosity, that only occurs in high mass, highly biased haloes, and one that can occur over a wide range of halo masses and leads to luminosities that are correlated with halo mass. This latter mode dominates at z<0.9. The CLFs for Type 2 and Type 1 AGNs are also constrained at z ≈0, and we find evidence that unobscured quasars are more likely to be found in higher mass halos than obscured quasars. Thus, the AGN unification model seems to fail at quasar luminosities.

  2. On the faint end of the high redshift AGN luminosity function

    CERN Document Server

    Shankar, F; Shankar, Francesco; Mathur, Smita; Shankar, Francesco; Mathur, Smita

    2007-01-01

    Using the results of recent optical surveys we conclude that the {\\it non}-detection of quasars down to faint magnitudes implies a significant flattening of the high redshift (z~6) optical active galactic nuclei (AGN) luminosity function for M_{1450}>-26.7. We find that all the data are consistent with a faint-end slope for the optical AGN luminosity function of \\beta=-2.2 and \\beta=-2.8, at the 90% and 99% confidence level respectively, flatter than the bright-end slope of \\beta'~ -3.2. We also show that X-ray deep surveys have probed even fainter magnitudes than the optical ones yielding more significant constraints on the shallow faint-end slope of the optical luminosity function. The inclusion of Type II AGN candidates, detected in the Chandra deep fields, hints towards an higher normalization for the total AGN luminosity function, if these sources lie at 5AGN formation and evolution in the context of cold dark matter cosmology. The comparison wi...

  3. On the faint end of the high redshift AGN luminosity function

    OpenAIRE

    Shankar, Francesco; Mathur, Smita

    2007-01-01

    Using the results of recent optical surveys we conclude that the {\\it non}-detection of quasars down to faint magnitudes implies a significant flattening of the high redshift (z~6) optical active galactic nuclei (AGN) luminosity function for M_{1450}>-24.7. We find that all the data are consistent with a faint-end slope for the optical AGN luminosity function of \\beta=-2.2 and \\beta=-2.8, at the 90% and 99% confidence level respectively, flatter than the bright-end slope of \\beta'~ -3.2. We a...

  4. The [OIII] emission line luminosity function of optically selected type-2 AGN from zCOSMOS

    CERN Document Server

    Bongiorno, A; Zamorani, G; Lamareille, F; Lanzuisi, G; Miyaji, T; Bolzonella, M; Carollo, C M; Contini, T; Kneib, J P; Le Fèvre, O; Lilly, S J; Mainieri, V; Renzini, A; Scodeggio, M; Bardelli, S; Brusa, M; Caputi, K; Civano, F; Coppa, G; Cucciati, O; de la Torre, S; de Ravel, L; Franzetti, P; Garilli, B; Halliday, C; Hasinger, G; Koekemoer, A M; Iovino, A; Kampczyk, P; Knobel, C; Kovac, K; Le Borgne, J F; Le Brun, V; Maier, C; Merloni, A; Nair, P; Pello, R; Peng, Y; Montero, E Perez; Ricciardelli, E; Salvato, M; Silverman, J; Tanaka, M; Tasca, L; Tresse, L; Vergani, D; Zucca, E; Abbas, U; Bottini, D; Cappi, A; Cassata, P; Cimatti, A; Guzzo, L; Leauthaud, A; Maccagni, D; Marinoni, C; McCracken, H J; Memeo, P; Meneux, B; Oesch, P; Porciani, C; Pozzetti, L; Scaramella, R

    2009-01-01

    We present a catalog of 213 type-2 AGN selected from the zCOSMOS survey. The selected sample covers a wide redshift range (0.15luminosity range 10^{5.5} < Lsun< L[OIII] < 10^{9.1} Lsun. We explore the intrinsic properties of these AGN and the relation to their X-ray emission (derived from the XMM-COSMOS observations). We study their evolution by computing the [OIII]5007A line luminosity function (LF) and we constrain the fraction of obscured AGN as a function of luminosity and redshift. The sample was selected on the basis of the optical emission line ratios, after applying a cut to the signal-to-noise ratio (S/N) of the relevant lines. We used the standard diagnostic diagrams [OIII]/Hbeta versus [NII]/Halpha and ([OIII]/Hbeta versus [SII]/Halpha) to isolate AGN in the redshift range 0.15

  5. TOOLS FOR COMPUTING THE AGN FEEDBACK: RADIO-LOUDNESS DISTRIBUTION AND THE KINETIC LUMINOSITY FUNCTION

    International Nuclear Information System (INIS)

    We studied the active galactic nucleus (AGN) radio emission from a compilation of hard X-ray-selected samples, all observed in the 1.4 GHz band. A total of more than 1600 AGNs with 2-10 keV de-absorbed luminosities higher than 1042 erg s-1 cm-2 were used. For a sub-sample of about fifty z ∼X = log(L 1.4/LX ), where L 1.4/LX = νL ν(1.4 GHz)/LX (2-10 keV). The probability distribution function of RX was functionally fitted as dependent on the X-ray luminosity and redshift, P(RX |LX , z). It roughly spans over six decades (-7X X ratio increases with decreasing X-ray luminosities and (possibly) with increasing redshift. No statistically significant difference was found between the radio properties of the X-ray absorbed (N H>1022 cm-2) and un-absorbed AGNs. Measurement of the probability distribution function of RX allowed us to compute the kinetic luminosity function and the kinetic energy density which, at variance with that assumed in many galaxy evolution models, is observed to decrease by about a factor of 5 at redshift below 0.5. About half of the kinetic energy density results in being produced by the more radio quiet (RX kin in converting the accreted mass energy into kinetic power (LK=εkin m-dot c2) is, on average, εkin ≅ 5 x 10-3. The data suggest a possible increase of εkin at low redshifts.

  6. The Hard X-ray 20-40 keV AGN Luminosity Function

    CERN Document Server

    Beckmann, V; Shrader, C R; Gehrels, N; Produit, N

    2006-01-01

    We have compiled a complete extragalactic sample based on 25,000 deg^2 to a limiting flux of 3E-11 ergs/cm**2/sec (7,000 deg^2 to a flux limit of 1E-11 ergs/cm**2/sec) in the 20 - 40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66+-0.11. The integration of the cumulative flux per unit area leads to f = 2.6E-10 ergs/cm**2/sec/sr, which is about 1% of the known 20 - 40 keV X-ray background. We present the first luminosity function of AGNs in the 20-40 keV energy range, based on 38 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma_1 = 0.8 below, and gamma_2 = 2.1 above the turn-over luminosity of L* = 2.4E43 ergs/sec. The emissivity of all INTEGRAL AGNs per unit volume is W(> 1E41 ergs/sec) = 2.8E38 ergs/sec/Mpc**3. These results are consis...

  7. The 5-10 keV AGN luminosity function at 0.01 < z < 4.0

    Science.gov (United States)

    Fotopoulou, S.; Buchner, J.; Georgantopoulos, I.; Hasinger, G.; Salvato, M.; Georgakakis, A.; Cappelluti, N.; Ranalli, P.; Hsu, L. T.; Brusa, M.; Comastri, A.; Miyaji, T.; Nandra, K.; Aird, J.; Paltani, S.

    2016-03-01

    The active galactic nuclei (AGN) X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the AGN population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH ~ 1023 cm-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01 separately for each survey and for the combined sample. We show that, according to Bayesian model selection, the preferred model for our dataset is the LDDE. Our estimation of the AGN luminosity function does not require any assumption on the AGN absorption and is in good agreement with previous works in the 2-10 keV energy band based on X-ray hardness ratios to model the absorption in AGN up to redshift three. Our sample does not show evidence of a rapid decline of the AGN luminosity function up to redshift four.

  8. Effect of spectral index distribution on estimating the AGN radio luminosity function

    CERN Document Server

    Yuan, Zunli; Zhou, Ming; Mao, Jirong

    2016-01-01

    In this paper, we scrutinize the effect of spectral index distribution on estimating the AGN (active galactic nucleus) radio luminosity function (RLF) by a Monte Carlo method. We find that the traditional bivariate RLF estimators can cause bias in varying degree. The bias is especially pronounced for the flat-spectrum radio sources whose spectral index distribution is more scattered. We believe that the bias is caused because the $K$-corrections complicate the truncation boundary on the $L-z$ plane of the sample, but the traditional bivariate RLF estimators have difficulty in dealing with this boundary condition properly. We suggest that the spectral index distribution should be incorporated into the RLF analysis process to obtain a robust estimation. This drives the need for a trivariate function of the form $\\Phi(\\alpha,z,L)$ which we show provides an accurate basis for measuring the RLF.

  9. Galaxy And Mass Assembly (GAMA): The 325 MHz Radio Luminosity Function of AGN and Star Forming Galaxies

    CERN Document Server

    Prescott, Matthew; Jarvis, M J; McAlpine, K; Smith, D J B; Fine, S; Johnston, R; Hardcastle, M J; Baldry, I K; Brough, S; Brown, M J I; Bremer, M N; Driver, S P; Hopkins, A M; Kelvin, L S; Loveday, J; Norberg, P; Obreschkow, D; Sadler, E M

    2016-01-01

    Measurement of the evolution of both active galactic nuclei (AGN) and star-formation in galaxies underpins our understanding of galaxy evolution over cosmic time. Radio continuum observations can provide key information on these two processes, in particular via the mechanical feedback produced by radio jets in AGN, and via an unbiased dust-independent measurement of star-formation rates. In this paper we determine radio luminosity functions at 325 MHz for a sample of AGN and star-forming galaxies by matching a 138 deg sq. radio survey conducted with the Giant Metrewave Radio Telescope (GMRT), with optical imaging and redshifts from the Galaxy And Mass Assembly (GAMA) survey. We find that the radio luminosity function at 325 MHz for star-forming galaxies closely follows that measured at 1.4 GHz. By fitting the AGN radio luminosity function out to $z = 0.5$ as a double power law, and parametrizing the evolution as ${\\Phi} \\propto (1 + z)^{k}$ , we find evolution parameters of $k = 0.92 \\pm 0.95$ assuming pure d...

  10. The 5 - 10 keV AGN luminosity function at 0.01

    CERN Document Server

    Fotopoulou, S; Georgantopoulos, I; Hasinger, G; Salvato, M; Georgakakis, A; Cappelluti, N; Ranalli, P; Hsu, L T; Brusa, M; Comastri, A; Miyaji, T; Nandra, K; Aird, J; Paltani, S

    2016-01-01

    The active galactic nuclei X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the active galactic nuclei (AGN) population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH=10^23 cm^-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01

  11. The evolution of the X-ray luminosity functions of unabsorbed and absorbed AGNs out to z~5

    CERN Document Server

    Aird, James; Georgakakis, Antonis; Nandra, Kirpal; Barro, Guillermo; Perez-Gonzalez, Pablo G

    2015-01-01

    We present new measurements of the evolution of the X-ray luminosity functions (XLFs) of unabsorbed and absorbed Active Galactic Nuclei (AGNs) out to z~5. We construct samples containing 2957 sources detected at hard (2-7 keV) X-ray energies and 4351 sources detected at soft (0.5-2 keV) energies from a compilation of Chandra surveys supplemented by wide-area surveys from ASCA and ROSAT. We consider the hard and soft X-ray samples separately and find that the XLF based on either (initially neglecting absorption effects) is best described by a new flexible model parametrization where the break luminosity, normalization and faint-end slope all evolve with redshift. We then incorporate absorption effects, separately modeling the evolution of the XLFs of unabsorbed ($20<\\log N_H<22$) and absorbed ($22<\\log N_H<24$) AGNs, seeking a model that can reconcile both the hard- and soft-band samples. We find that the absorbed AGN XLF generally has a lower break luminosity, a higher normalization, and a steeper...

  12. Gamma-ray luminosity function of gamma-ray bright AGNs

    Institute of Scientific and Technical Information of China (English)

    Debbijoy Bhattacharya; P. Sreekumar; R. Mukherjee

    2009-01-01

    Detection of γ-ray emissions from a class of active galactic nuclei (viz blazars),has been one of the important findings from the Compton Gamma-Ray Observatory (CGRO). However, their-γ-ray luminosity function has not been well determined. Few at-tempts have been made in earlier works, where BL Lacs and Flat Spectrum Radio Quasars (FSRQs) have been considered as a single source class. In this paper, we investigated the evolution and γ-ray luminosity function of FSRQs and BL Lacs separately. Our investi-gation indicates no evolution for BL Lacs, however FSRQs show significant evolution. Pure luminosity evolution is assumed for FSRQs and exponential and power law evolu-tion models are examined. Due to the small number of sources, the low luminosity end index of the luminosity function for FSRQs is constrained with an upper limit. BL Lac lu-minosity function shows no signature of break. As a consistency check, the model source distributions derived from these luminosity functions show no significant departure from the observed source distributions.

  13. Faint high-redshift AGN in the Chandra Deep Field South: the evolution of the AGN luminosity function and black hole demography

    CERN Document Server

    Fiore, F; Grazian, A; Menci, N; Shankar, F; Santini, P; Piconcelli, E; Koekemoer, A M; Fontana, A; Boutsia, K; Castellano, M; Lamastra, A; Malacaria, C; Feruglio, C; Mathur, S; Miller, N; Pannella, M

    2011-01-01

    We present detection and analysis of faint X-ray sources in the Chandra deep field south (CDFS) using the 4 Msec Chandra observation and adopting a new detection algorithm, based on a targeted search at the position of known high-z galaxies. This optimized technique results in the identification of 54 z>3 AGNs, 29 of which are new detections. Applying stringent completeness criteria, we derive AGN luminosity functions in the redshift bins 3-4, 4-5 and >5.8 and for 42.753 (18+17-10%). Their optical counterparts are not strongly reddened and we thus conclude that the size of the X-ray absorber is likely smaller than the dust sublimation radius. We finally report the discovery of a highly star-forming galaxy at z=3.47. If confirmed, this would be one of the farthest objects in which stellar sources are detected in X-rays.

  14. The 2-10 keV unabsorbed luminosity function of AGN from the LSS, CDFS, and COSMOS surveys

    Science.gov (United States)

    Ranalli, P.; Koulouridis, E.; Georgantopoulos, I.; Fotopoulou, S.; Hsu, L.-T.; Salvato, M.; Comastri, A.; Pierre, M.; Cappelluti, N.; Carrera, F. J.; Chiappetti, L.; Clerc, N.; Gilli, R.; Iwasawa, K.; Pacaud, F.; Paltani, S.; Plionis, E.; Vignali, C.

    2016-05-01

    The XMM-Large scale structure (XMM-LSS), XMM-Cosmological evolution survey (XMM-COSMOS), and XMM-Chandra deep field south (XMM-CDFS) surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and point spread function. Therefore this is one of the best samples available to determine the 2-10 keV luminosity function of active galactic nuclei (AGN) and their evolution. The samples and the relevant corrections for incompleteness are described. A total of 2887 AGN is used to build the LF in the luminosity interval 1042-1046 erg s-1 and in the redshift interval 0.001-4. A new method to correct for absorption by considering the probability distribution for the column density conditioned on the hardness ratio is presented. The binned luminosity function and its evolution is determined with a variant of the Page-Carrera method, which is improved to include corrections for absorption and to account for the full probability distribution of photometric redshifts. Parametric models, namely a double power law with luminosity and density evolution (LADE) or luminosity-dependent density evolution (LDDE), are explored using Bayesian inference. We introduce the Watanabe-Akaike information criterion (WAIC) to compare the models and estimate their predictive power. Our data are best described by the LADE model, as hinted by the WAIC indicator. We also explore the recently proposed 15-parameter extended LDDE model and find that this extension is not supported by our data. The strength of our method is that it provides unabsorbed, non-parametric estimates, credible intervals for luminosity function parameters, and a model choice based on predictive power for future data. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.Tables with the samples of the posterior probability distributions

  15. VizieR Online Data Catalog: 2-10keV luminosity function of AGN (Ranalli+, 2016)

    Science.gov (United States)

    Ranalli, P.; Koulouridis, E.; Georgantopoulos, I.; Fotopoulou, S.; Hsu, L.-T.; Salvato, M.; Comastri, A.; Pierre, M.; Cappelluti, N.; Carrera, F. J.; Chiappetti, L.; Clerc, N.; Gilli, R.; Iwasawa, K.; Pacaud, F.; Paltani, S.; Plionis, E.; Vignali, C.

    2016-02-01

    The XMM-LSS, XMM-CDFS, and XMM-COSMOS are three surveys with complementary properties in terms of luminosity and redshift coverage. We used these three surveys to derive Bayesian estimates of the unabsorbed luminosity function (LF) of AGN in the 2-10keV band. The LF estimates are presented as a set of samples from the posterior probability distribution of the LF parameters. The LF is parameterised as a double power-law, with either the luminosity and density evolution (LADE) model, or the luminosity-dependent density evolution (LDDE) model. The double power-law is described by Eq.(10) in the paper. The LADE and LDDE models are described by Eqs.(11-14) and Eqs.(15-17), respectively. A Fortran 2008 implementation of these models can be found in file src2/lumf_funcs.f90 of the LFTools package, in the classes doublepowerlaw, ladevol, and lddevol (see the paper). (8 data files).

  16. Cosmological Evolution of the Hard X-ray AGN Luminosity Function and the Origin of the Hard X-ray Background

    OpenAIRE

    Ueda, Yoshihiro; Akiyama, Masayuki; Ohta, Kouji; Miyaji, Takamitsu

    2003-01-01

    We investigate the cosmological evolution of the hard X-ray luminosity function (HXLF) of Active Galactic Nuclei (AGN) in the 2-10 keV luminosity range of 10^{41.5} - 10^{46.5} erg s^-1 as a function of redshift up to 3. From a combination of surveys conducted at photon energies above 2 keV with HEAO1, ASCA, and Chandra, we construct a highly complete (>96%) sample consisting of 247 AGNs over the wide flux range of 10^{-10} - 3.8*10^{-15} erg cm^-2 s^-1 (2-10 keV). For our purpose, we develop...

  17. AGN Broad Line Regions Scale with Bolometric Luminosity

    CERN Document Server

    Trippe, Sascha

    2015-01-01

    The masses of supermassive black holes in active galactic nuclei (AGN) can be derived spectroscopically via virial mass estimators based on selected broad optical/ultraviolet emission lines. These estimates commonly use the line width as a proxy for the gas speed and the monochromatic continuum luminosity as a proxy for the radius of the broad line region. However, if the size of the broad line region scales with bolometric rather than monochromatic AGN luminosity, mass estimates based on different emission lines will show a systematic discrepancy which is a function of the color of the AGN continuum. This has actually been observed in mass estimates based on H-alpha / H-beta and C IV lines, indicating that AGN broad line regions indeed scale with bolometric luminosity. Given that this effect seems to have been overlooked as yet, currently used single-epoch mass estimates are likely to be biased.

  18. A possible bias on the estimate of Lbol/Ledd in AGN as a function of luminosity and redshift

    CERN Document Server

    Lamastra, A; Perola, G C; Lamastra, Alessandra; Matt, Giorgio

    2006-01-01

    The BH mass (and the related Eddington ratio) in broad line AGN is usually evaluated by combining estimates (often indirect) of the BLR radius and of the FWHM of the broad lines, under the assumption that the BLR clouds are in Keplerian motion around the BH. Such an evaluation depends on the geometry of the BLR. There are two major options for the BLR configuration: spherically symmetric or ``flattened''. In the latter case the inclination to the line of sight becomes a relevant parameter. This paper is devoted to evaluate the bias on the estimate of the Eddington ratio when a spherical geometry is assumed (more generally when inclination effects are ignored), while the actual configuration is ``flattened'', as some evidence suggests. This is done as a function of luminosity and redshift, on the basis of recent results which show the existence of a correlation between the fraction of obscured AGN and these two parameters up to at least z=2.5. The assumed BLR velocity field is akin to the ``generalized thick d...

  19. The Dark Matter Halos of Moderate Luminosity AGN

    Science.gov (United States)

    Leauthaud, Alexie; Benson, Andrew; Civano, Francesca M.; Coil, Alison L.; Bundy, Kevin; Massey, Richard; Schramm, Malte; Schulze, Andreas; Capak, Peter L.; Elvis, Martin; Kulier, Andrea; Rhodes, Jason

    2015-01-01

    Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter halos in which they reside is key to constraining how black-hole fueling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modeling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. Instead, in this work, we use host mass as a prior to derive halo masses for moderate luminosity AGN. Using 382 moderate luminosity X-ray AGN at zlive in group-scale dark matter halos---nearly half reside in halos with Mhalo ~ 10^12.5 Msun. By highlighting the relatively ``normal'' way in which moderate luminosity X-ray AGN hosts occupy halos, our results suggest that the environmental signature of distinct fueling modes for luminous QSOs compared to moderate luminosity X-ray AGN is less obvious than previously claimed.

  20. Bolometric Luminosity Correction of H2O Maser AGNs

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2014-09-01

    For the H2O maser host AGN sample, we derived their bolometric luminosity corrections, based on their X-ray data and [O III] emission line luminosities. Our results for maser AGNs is comparable to that of non-maser AGNs.

  1. A remarkably flat relationship between the average star formation rate and AGN luminosity for distant X-ray AGN

    CERN Document Server

    Stanley, F; Alexander, D M; Swinbank, A M; Aird, J A; Del Moro, A; Hickox, R C; Mullaney, J R

    2015-01-01

    In this study we investigate the relationship between the star formation rate, SFR, and AGN luminosity, L(AGN), for ~2000 X-ray detected AGN. The AGN span over three orders of magnitude in X-ray luminosity (10^(42) < L(2-8keV) < 10^(45.5) erg/s) and are in the redshift range z = 0.2 - 2.5. Using infrared (IR) photometry (8 - 500um), including deblended Spitzer and Herschel images and taking into account photometric upper limits, we decompose the IR spectral energy distributions into AGN and star formation components. Using the IR luminosities due to star formation, we investigate the average SFRs as a function of redshift and AGN luminosity. In agreement with previous studies, we find a strong evolution of the average SFR with redshift, tracking the observed evolution of the overall star forming galaxy population. However, we find that the relationship between the average SFR and AGN luminosity is flat at all redshifts and across all the AGN luminosities investigated. By comparing to empirical models, w...

  2. The 2-10 keV unabsorbed luminosity function of AGN from the XMM-Newton LSS, CDFS and COSMOS surveys

    CERN Document Server

    Ranalli, P; Georgantopoulos, I; Fotopoulou, S; Hsu, L -T; Salvato, M; Comastri, A; Pierre, M; Cappelluti, N; Carrera, F J; Chiappetti, L; Clerc, N; Gilli, R; Iwasawa, K; Pacaud, F; Paltani, S; Plionis, E; Vignali, C

    2015-01-01

    The XMM-LSS, XMM-COSMOS, and XMM-CDFS surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and PSF. Therefore this is one of the best samples available to determine the 2-10 keV luminosity function of AGN and its evolution. The samples and the relevant corrections for incompleteness are described. A total of 2887 AGN is used to build the LF in the luminosity interval 10^42-10^46 erg/s, and in the redshift interval 0.001-4. A new method to correct for absorption by considering the probability distribution for the column density conditioned on the hardness ratio is presented. The binned luminosity function and its evolution is determined with a variant of the Page-Carrera method, improved to include corrections for absorption and to account for the full probability distribution of photometric redshifts. Parametric models, namely a double power-law with LADE or LDDE evolution, are explored using Bayesian in...

  3. Cosmological simulations of black hole growth: AGN luminosities and downsizing

    CERN Document Server

    Michaela, Hirschmann; Alexandro, Saro; Stefano, Borgani; Andreas, Burkert

    2013-01-01

    In this study, we present a detailed, statistical analysis of black hole (BH) growth and the evolution of active galactic nuclei (AGN) using cosmological hydrodynamic simulations run down to z=0. The simulations self-consistently follow radiative cooling, star formation, metal enrichment, BH growth and associated feedback processes from both supernovae typeII/Ia and AGN. We consider two simulation runs, one with a large co-moving volume of (128 Mpc/h)^3 and one with a smaller volume of (48 Mpc/h)^3 but with a higher mass resolution. Consistently with previous results, our simulations are in reasonably good agreement with BH properties of the local Universe. Furthermore, they can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low- and the high-luminosity end up to z=2.5. The smaller but higher resolution run can match the observational data of the low bolometric luminosity end even up to z=4-5. We also perform a direct comparison with the observed soft and hard X-ra...

  4. Bright and Faint Ends of Lyα Luminosity Functions at z = 2 Determined by the Subaru Survey: Implications for AGNs, Magnification Bias, and ISM H I Evolution

    Science.gov (United States)

    Konno, Akira; Ouchi, Masami; Nakajima, Kimihiko; Duval, Florent; Kusakabe, Haruka; Ono, Yoshiaki; Shimasaku, Kazuhiro

    2016-05-01

    We present the Lyα luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3137 Lyα emitters (LAEs) at z = 2.2 in five independent blank fields. This sample of LAEs is the largest to date and covers a very wide Lyα luminosity range of {log}{L}{Lyα }=41.7{--}44.4 erg s‑1. We determine the Lyα LF at z = 2.2 with unprecedented accuracy and obtain the best-fit Schechter parameters of {L}{Lyα }*={5.29}-1.13+1.67× {10}42 erg s‑1, {φ }{Lyα }*={6.32}-2.31+3.08× {10}-4 Mpc‑3, and α =-{1.75}-0.09+0.10, showing a steep faint-end slope. We identify a significant hump at the LF bright end ({log}{L}{Lyα }\\gt 43.4 erg s‑1). Because all of the LAEs in the bright-end hump have a bright counterpart(s) in either the X-ray, UV, or radio data, this bright-end hump is not made by gravitational lensing magnification bias but by active galactic nuclei (AGNs). These AGNs allow us to derive the AGN UV LF at z ∼ 2 down to the faint magnitude limit of M UV ≃ ‑22.5 and to constrain the faint-end slope of the AGN UV LF, α AGN = ‑1.2 ± 0.1, which is flatter than those at z > 4. Based on the Lyα and UV LFs from our and previous studies, we find an increase of Lyα escape fraction {f}{esc}{Lyα } from z ∼ 0 to 6 by two orders of magnitude. This large {f}{esc}{Lyα } increase can be explained neither by the evolution of stellar population nor by outflow alone, but by the evolution of neutral hydrogen H i density in the interstellar medium that enhances dust attenuation for Lyα by resonance scattering. Our uniform expanding shell models suggest that the typical H i column density decreases from {N}{{H}{{I}}}∼ 7× {10}19 (z ∼ 0) to ∼1 × 1018 cm‑2 (z ∼ 6) to explain the large {f}{esc}{Lyα } increase.

  5. The Mass-Luminosity Relation in AGN

    OpenAIRE

    Wandel, Amri

    1998-01-01

    Probably the most fundamental characteristic of the quasar-AGN power house, the mass of the central black hole, is the least well known. I review the three main classes of mass estimation methods---broad emission-line kinematics, X-ray variability and accretion-disk modeling, and the masses they give in terms of the Eddington ratio, $L/L_{\\rm Edd}$. The broad emission lines are probably the best probe of the central mass. They provide mass estimates that suggest a narrow spread for the Edding...

  6. Disc outflows and high-luminosity true type 2 AGN

    Science.gov (United States)

    Elitzur, Moshe; Netzer, Hagai

    2016-06-01

    The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such `true type 2 AGN' are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad-line emission can disappear at luminosities as high as ˜4 × 1046 erg s-1 and any Eddington ratio, though more detections can be expected at Eddington ratios below ˜1 per cent. Our results are applicable to every disc outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. While other factors, such as changes in spectral energy distribution or covering factor, can affect the intensities of broad emission lines, within this scenario they can only produce true type 2 AGN of higher luminosity then those prescribed by mass conservation.

  7. Luminosity Function of GRBs

    CERN Document Server

    Sethi, S; Sethi, Shiv

    2001-01-01

    We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count--flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal distribution, (b) Schechter distribution, and (c) Scale-free distribution. We assume several models of the evolution of the GRB population for each luminosity function. Our analysis shows that: (a) log-normal is the only luminosity function that is compatible with both the observations. This result is independent of the GRB evolution model, (b) for log-normal function, the average photon luminosity $L_0$ and the width of the luminosity function $\\sigma$ that are compatible with both the observations fall in the range: $10^{55} sec^{-1} \\la L_0 \\la 10^{56} sec^{-1}$ and $2 \\la \\sigma \\la 3$, (c) the agreement of observations with other luminosity functions requires the GRB population to evolve more strongly than the evolution of the star-formation rate of the universe.

  8. Disk Outflows and High-Luminosity True Type 2 AGN

    CERN Document Server

    Elitzur, Moshe

    2016-01-01

    The absence of intrinsic broad line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such "true type 2 AGN" are inherent to the disk-wind scenario for the broad line region: Broad line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disk. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad line emission can disappear at luminosities as high as about 4x$10^{46}$ erg s$^{-1}$ and any Eddington ratio, though more detections can be expected at Eddington ratios below about 1%. Our results are applicable to every disk outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. ...

  9. The Properties of Low-Luminosity AGN: Variability, Accretion Rate, Black Hole Mass and Color

    Science.gov (United States)

    Oleas, Juan; Podjed, Stephanie; Sarajedini, Vicki

    2016-01-01

    We present the results from a study of ~5000 Broad-Line selected AGN from the Sloan Digital Sky Survey DR7. Galaxy and AGN templates have been fit to the SDSS spectra to isolate the AGN component. The sources have absolute magnitudes in the range -23 variability analysis reveals that the anti-correlation between luminosity and variability amplitude continues to the faintest AGN in our sample (Gallastegui-Aizpun & Sarajedini 2014), though the underlying cause of the relation is still poorly understood. To address this, we further explore the connection between AGN luminosity and variability through measurement of the Hβ line width to determine black hole mass and accretion rate. We find that AGN with the highest variability amplitudes at a given luminosity appear to have lower accretion rates compared to low amplitude variables. We also investigate correlations with AGN color and accretion rate among these low-luminosity AGN.

  10. properties and luminosity functions

    Directory of Open Access Journals (Sweden)

    Hektor Monteiro

    2007-01-01

    Full Text Available In this article, we present an investigation of a sample of 1072 stars extracted from the Villanova Catalog of Spectroscopically Identified White Dwarfs (2005 on-line version, studying their distribution in the Galaxy, their physical properties and their luminosity functions. The distances and physical properties of the white dwarfs are determined through interpolation of their (B-V or (b-y colors in model grids. The solar position relative to the Galactic plane, luminosity function, as well as separate functions for each white dwarf spectral type are derived and discussed. We show that the binary fraction does not vary significantly as a function of distance from the Galactic disk out to 100 pc. We propose that the formation rates of DA and non-DAs have changed over time and/or that DAs evolve into non-DA types. The luminosity functions for DAs and DBs have peaks possibly related to a star burst event.

  11. Do Moderate-Luminosity AGN Suppress Star Formation?

    CERN Document Server

    Schawinski, Kevin; Simmons, Brooke; Urry, C Megan; Treister, Ezequiel; Kaviraj, Sugata; Kushkuley, Bronika

    2009-01-01

    The growth of supermassive black holes and their host galaxies are thought to be linked, but the precise nature of this symbiotic relationship is still poorly understood. Both observations and simulations of galaxy formation suggest that the energy input from active galactic nuclei (AGN), as the central supermassive black hole accretes material and grows, heats the interstellar material and suppresses star formation. In this Letter, we show that most host galaxies of moderate-luminosity supermassive black holes in the local universe have intermediate optical colors that imply the host galaxies are transitioning from star formation to quiescence, the first time this has been shown to be true for all AGN independent of obscuration. The intermediate colors suggest that star formation in the host galaxies ceased roughly 100 Myr ago. This result indicates that either the AGN are very long-lived, accreting for more than 1 Gyr beyond the end of star formation, or there is a ~100 Myr time delay between the shutdown o...

  12. Galaxy mergers and active nuclei. I. The luminosity function

    International Nuclear Information System (INIS)

    Galaxy mergers may boost the tidal disruption rate of stars near a massive central black hole in the nucleus of a galaxy, producing active galactic nuclei (AGNs) with nonthermal luminosities up to 1047 ergs s-1. We derive a bolometric luminosity function for AGNs based on this process. Our main assumptions are: (1) galaxies contain massive central black holes, and (2) the density structure of galactic nuclei is similar to that of the Milky Way. The merging rate is estimated from the two-point correlation function of galaxies. Our bolometric luminosity function can be compared with observed radio, optical, and X-ray luminosity functions by assuming that the energy emitted at these wavebands is proportional to bolometric luminosity. This assumption is based on the similarity between observed luminosity functions at high luminosities. The observed and theoretical functions have the same characteristics: at high luminosities they behave as a power law with index of about -1.4. The function flattens below L/sup direct-product/roughly-equal1044 ergs s-1. As an example we show that the model is capable of reproducing in detail the observed (bivariate) radio luminosity function. The luminosity coordinate of the break in the (bivariate) radio luminosity function at L/sup direct-product/ yields an estimate of the central black-hole mass as a function of (stellar) galactic luminosity. The space-density coordinate of the break indicates that the mean mass ratio of the interacting galaxies is larger than 20

  13. On the variable nature of low luminosity AGN

    Science.gov (United States)

    Hernandez-Garcia, Lorena

    2015-09-01

    X-ray variability is very common in active galactic nuclei (AGN), but it is still unknown if these variations occur similarly in different families of AGN. The main purpose of this work is to disentangle the true structure of low ionization nuclear emission line regions (LINERs) compared to Seyfert 2s by the study of their X-ray variations. We assembled the X-ray spectral properties, as well as the X-ray variability pattern(s), which were obtained from simultaneous spectral fittings and letting different parameters to vary in the model, derived from our previous analyses (Hernández-García et al. 2013, 2014, 2015). We find that Seyfert 2s need more complex models to fit their spectra than LINERs. Among the spectral parameters, major differences are observed in the soft (0.5-2 keV) and hard (2-10 keV) X-ray luminosities, and the Eddington ratios, which are higher in Seyfert 2s. Differences are observed also in the hard column densities, temperatures, and black hole masses, although less significant. Short-term X-ray variations cannot be claimed, while long-term variability is very common in both families. An exception is found for Compton-thick sources, which do not vary, most probably because the AGN is not accesible in the 0.5--10 keV energy band. The changes are mostly related with variations in the nuclear continuum, but other patterns of variability show that variations in the absorbers (more common in Seyfert 2s) and at soft energies can be present in a few cases. Variations at UV frequencies are observed only in LINER nuclei. The X-ray variations occur similarly in LINERs and Seyfert 2s, i.e., they are related to the nuclear continuum, although they might have different accretion mechanisms, being more efficient in Seyfert 2s. Absorption variations and changing-look sources are not usually observed in LINERs. However, UV nuclear variations are common among LINERs, indicating an unobstructed view of the inner disc where the UV emission might take place. We

  14. Optical Variability Properties of High Luminosity AGN Classes

    Indian Academy of Sciences (India)

    C. S. Stalin; Gopal-Krishna; Ram Sagar; Paul J. Wiita

    2004-03-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range ≃ 0.2 to ≃ 2.2. The sample, matched in the optical luminosity – redshift (-) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single qusar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of INOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOVamplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020; 5GHz

  15. Modeling the cosmological co-evolution of supermassive black holes and galaxies: I. BH scaling relations and the AGN luminosity function

    OpenAIRE

    Marulli, Federico; Bonoli, Silvia; Branchini, Enzo; Moscardini, Lauro; Springel, Volker

    2007-01-01

    We model the cosmological co-evolution of galaxies and their central supermassive black holes (BHs) within a semi-analytical framework developed on the outputs of the Millennium Simulation. This model, described in detail in Croton et al. (2006) and De Lucia & Blaizot (2007), introduces a `radio mode' feedback from Active Galactic Nuclei (AGN) at the centre of X-ray emitting atmospheres in galaxy groups and clusters. Thanks to this mechanism, the model can simultaneously explain: (i) the low ...

  16. Clustering, Cosmology and a New Era of Black Hole Demographics -- I. The Conditional Luminosity Function of Active Galactic Nuclei

    CERN Document Server

    Ballantyne, D R

    2016-01-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of active galactic nuclei (AGN) evolution stretching back to $z \\sim 5$. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, this paper presents a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific $z$. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function -- all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method ...

  17. Obscuration in AGNs: near-infrared luminosity relations and dust colors

    CERN Document Server

    Burtscher, L; Davies, R I; Janssen, A; Lutz, D; Rosario, D; Contursi, A; Genzel, R; Gracia-Carpio, J; Lin, M -Y; Schnorr-Mueller, A; Sternberg, A; Sturm, E; Tacconi, L

    2015-01-01

    We combine two approaches to isolate the AGN luminosity at near-infrared wavelengths and relate the near-IR pure AGN luminosity to other tracers of the AGN. Using integral-field spectroscopic data of an archival sample of 51 local AGNs, we estimate the fraction of non-stellar light by comparing the nuclear equivalent width of the stellar 2.3 micron CO absorption feature with the intrinsic value for each galaxy. We compare this fraction to that derived from a spectral decomposition of the integrated light in the central arc second and find them to be consistent with each other. Using our estimates of the near-IR AGN light, we find a strong correlation with presumably isotropic AGN tracers. We show that a significant offset exists between type 1 and type 2 sources in the sense that type 1 sources are 7 (10) times brighter in the near-IR at log L_MIR = 42.5 (log L_X = 42.5). These offsets only becomes clear when treating infrared type 1 sources as type 1 AGNs. All AGNs have very red near-to-mid-IR dust colors. T...

  18. Do Radio Jets Contribute to Driving Ionized Gas Outflows in Moderate Luminosity Type 2 AGN?

    Science.gov (United States)

    Fowler, Julia; Sajina, Anna; Lacy, Mark

    2016-01-01

    This poster examines the role of AGN-driven feedback in low to intermediate power radio galaxies. We begin with [OIII] measurements of ionized gas outflows in 29 moderate AGN-luminosity z~0.3-0.7 dust-obscured Type 2 AGN. We aim to examine the relative role of the AGN itself, of star-formation and of nascent radio jets in driving these outflows. The strength of the AGN and star formation are based on the [OIII] luminosities, and the far-IR luminosities respectively. For the radio jets, we present multi-frequency radio (X, S, and L-bands) JVLA imaging of our sample, which allows us both to constrain the overall radio power, but also look for signatures of young radio sources, including Giga-hertz Peaked Spectrum (GPS) sources, as well as small-scale jets. While radio jet-driven outflows are well known for powerful radio-loud galaxies, this study allows us to constrain the degree to which this mechanism is significant at more modest radio luminosities of L5GHz~10^22-25 W/Hz.

  19. The OH Megamaser Luminosity Function

    OpenAIRE

    Darling, Jeremy; Giovanelli, Riccardo

    2002-01-01

    We present the 1667 MHz OH megamaser luminosity function derived from a single flux-limited survey. The Arecibo Observatory OH megamaser (OHM) survey has doubled the number of known OH megamasers, and we list the complete catalog of OHMs detected by the survey here, including three redetections of known OHMs. OHMs are produced in major galaxy mergers which are (ultra)luminous in the far-infrared. The OH luminosity function follows a power law in integrated line luminosity, $\\Phi \\propto L_{OH...

  20. THE DETECTION OF EXTREME LOW-LUMINOSITY AGNS

    Directory of Open Access Journals (Sweden)

    D. M. Neri-Larios

    2011-01-01

    Full Text Available Exploramos el diagrama de diagn stico que utiliza la raz n de l neas de emisi n ([NII]h6584 A/H frente al ancho equivalente de [NII]h6584 A, propuesto por Coziol et al. (1998 a una muestra obtenida del SDSS DR5 para separar las galaxias dominadas por formaci n estelar y galaxias con n cleo activo (AGNs de baja luminosidad. Este diagrama de diagn stico no necesita las l neas clasicas de emisi n como [OIII]h5007 A, o H para clasificar el tipo de actividad. Se demuestra emp ricamente que esta combinaci n de l neas de emisi n se puede utilizar para buscar en los llamados AGN de baja luminosidad.

  1. AGN host galaxy mass function in COSMOS. Is AGN feedback responsible for the mass-quenching of galaxies?

    Science.gov (United States)

    Bongiorno, A.; Schulze, A.; Merloni, A.; Zamorani, G.; Ilbert, O.; La Franca, F.; Peng, Y.; Piconcelli, E.; Mainieri, V.; Silverman, J. D.; Brusa, M.; Fiore, F.; Salvato, M.; Scoville, N.

    2016-04-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate, that is, λSAR, the distribution function (SARDF), up to z ~ 2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best-fit model characterizes the SARDF as a double power-law with mass-dependent but redshift-independent break, whose low λSAR slope flattens with increasing redshift while the normalization increases. This implies that for a given stellar mass, higher λSAR objects have a peak in their space density at earlier epoch than the lower λSAR objects, following and mimicking the well-known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with an almost constant M∗⋆ and a low-mass slope α that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that up to log (M⋆/M⊙) ~ 11.5, the ratio of AGN host galaxies to star-forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate subclasses with a previously published phenomenological model prediction for the "transient" population, which are galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, that is, M⋆ > 1010.7 M⊙, feedback from luminous AGN (log Lbol ≳ 46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.

  2. The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses

    Science.gov (United States)

    Leauthaud, Alexie; J. Benson, Andrew; Civano, Francesca; L. Coil, Alison; Bundy, Kevin; Massey, Richard; Schramm, Malte; Schulze, Andreas; Capak, Peter; Elvis, Martin; Kulier, Andrea; Rhodes, Jason

    2015-01-01

    Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter haloes in which they reside is key to constraining how black hole fuelling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modelling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. In this work, we show that better constraints can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to the fiducial stellar-to-halo mass relation (SHMR) derived for all galaxies, irrespective of nuclear activity. Our technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone. Using 382 moderate luminosity X-ray AGN at z live in medium size groups - nearly half reside in relatively low mass haloes with M200b ˜ 1012.5 M⊙. The AGN occupation function is well described by the same form derived for all galaxies but with a lower normalization - the fraction of haloes with AGN in our sample is a few per cent. The number of AGN satellite galaxies scales as a power law with host halo mass with a power-law index α = 1. By highlighting the relatively `normal' way in which moderate luminosity X-ray AGN hosts occupy haloes, our results suggest that the environmental signature of distinct fuelling modes for luminous quasars compared to moderate luminosity X-ray AGN is less obvious than previously claimed.

  3. The jet of the Low Luminosity AGN of M81

    Directory of Open Access Journals (Sweden)

    Alberdi A.

    2013-12-01

    Full Text Available In this contribution, we summarize our main results of a big campaign of global VLBI observations of the AGN in M81 (M81* phase-referenced to the radio supernova SN 1993J. Thanks to the precise multi-epoch and multi-frequency astrometry, we have determined the normalized core-shift of the relativistic jet of M81* and estimated both the magnetic field and the particle density at the jet base. We have also found evidence of jet precession in M81* coming from the systematic time evolution of the jet orientation correlated with changes in the overall flux density.

  4. The clustering amplitude of X-ray-selected AGN at z ˜ 0.8: evidence for a negative dependence on accretion luminosity

    Science.gov (United States)

    Mountrichas, G.; Georgakakis, A.; Menzel, M.-L.; Fanidakis, N.; Merloni, A.; Liu, Z.; Salvato, M.; Nandra, K.

    2016-04-01

    The northern tile of the wide-area and shallow XMM-XXL X-ray survey field is used to estimate the average dark matter halo mass of relatively luminous X-ray-selected active galactic nucleus (AGN) [log {L}_X (2-10 keV)= 43.6^{+0.4}_{-0.4} erg s^{-1}] in the redshift interval z = 0.5-1.2. Spectroscopic follow-up observations of X-ray sources in the XMM-XXL field by the Sloan telescope are combined with the VIMOS Public Extragalactic Redshift Survey spectroscopic galaxy survey to determine the cross-correlation signal between X-ray-selected AGN (total of 318) and galaxies (about 20 000). We model the large scales (2-25 Mpc) of the correlation function to infer a mean dark matter halo mass of log M / (M_{{⊙}} h^{-1}) = 12.50 ^{+0.22} _{-0.30} for the X-ray-selected AGN sample. This measurement is about 0.5 dex lower compared to estimates in the literature of the mean dark matter halo masses of moderate-luminosity X-ray AGN [LX(2-10 keV) ≈ 1042-1043 erg s- 1] at similar redshifts. Our analysis also links the mean clustering properties of moderate-luminosity AGN with those of powerful ultraviolet/optically selected QSOs, which are typically found in haloes with masses few times 1012 M⊙. There is therefore evidence for a negative luminosity dependence of the AGN clustering. This is consistent with suggestions that AGN have a broad dark matter halo mass distribution with a high mass tail that becomes subdominant at high accretion luminosities. We further show that our results are in qualitative agreement with semi-analytic models of galaxy and AGN evolution, which attribute the wide range of dark matter halo masses among the AGN population to different triggering mechanisms and/or black hole fuelling modes.

  5. The Globular Cluster Luminosity Function

    OpenAIRE

    McLaughlin, Dean E.

    2003-01-01

    The main aspects of the globular cluster luminosity function needing to be explained by a general theory of cluster formation are reviewed, and the importance of simultaneously understanding globular cluster systematics (the fundamental plane) within such a theory is pointed out.

  6. The Dark Matter Halos of Moderate Luminosity X-ray AGN as Determined from Weak Gravitational Lensing and Host Stellar Masses

    CERN Document Server

    Leauthaud, A; Civano, F; Coil, A L; Bundy, K; Massey, R; Schramm, M; Schulze, A; Capak, P; Elvis, M; Kulier, A; Rhodes, J

    2014-01-01

    Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter halos in which they reside is key to constraining how black-hole fueling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modeling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. In this work, we show that better constraints can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to a fiducial stellar-to-halo mass relation (SHMR) derived for all galaxies. Our technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone. Using 382 moderate luminosity X-ray AGN at z<1 fro...

  7. Luminosity function of white dwarfs

    International Nuclear Information System (INIS)

    Trigonometric parallaxes, optical colors, and spectrophotometry are used to derive an empirical luminosity function for cool white dwarfs using the 1/V(max) method. To facilitate comparison with theoretical cooling curves, relations for cool white dwarfs are estimated for T(eff) versus M(V) and for M(V) versus M(bol). The results show that a downturn occurs in the distribution of cool degenerate stars near log luminosity equals about -4.4. The indicated local space density of observed degenerate dwarfs is 0.003 stars/pc exp 3, which corresponds to about 1 percent of the dynamical mass density in the solar neighborhood. 107 references

  8. The white dwarf luminosity function

    CERN Document Server

    García-Berro, Enrique

    2016-01-01

    White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for $\\sim 10$ Gyr. Their observed properties provide information about the history of the Galaxy, its dark matter content and a host of other interesting astrophysical problems. Examples of these include an independent determination of the past history of the local star formation rate, identification of the objects responsible for the reported microlensing events, constraints on the rate of change of the gravitational constant, and upper limits to the mass of weakly interacting massive particles. To carry on these tasks the essential observational tools are the luminosity and mass functions of white dwarfs, whereas the theoretical tools are the evolutionary sequences of white dwarf progenitors, and the corresponding white dwarf cooling sequences. In particular, the observed white dwarf luminosity function is the key manifestation of the white dwarf cooling theory, although other...

  9. Unification of Low Luminosity AGN and Hard State X-ray Binaries

    Science.gov (United States)

    Connolly, S.

    2015-09-01

    We present X-ray spectral variability of four low accretion rate and low luminosity AGN (LLAGN)- M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the 'softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely cause of spectral variability is found to be hardening of the photon index of the power law component with increasing luminosity. Such a correlation has been seen previously within samples of low accretion rate AGN but in only one case has it been seen within observations of a single AGN. Here we show that such behaviour may be very common in LLAGN. A similar anticorrelation is found in X-ray binary systems in the 'hard state', at low accretion rates similar to those of the LLAGN discussed here. Our observations thus imply that LLAGN are the active galaxy equivalent of hard state X-ray binaries.

  10. The Mid-Infrared Luminosity Evolution and Luminosity Function of Quasars with SDSS and WISE

    CERN Document Server

    Singal, J; Gerber, A

    2016-01-01

    We determine the 22$\\mu$m luminosity evolution and luminosity function for quasars from a data set of over 20,000 objects obtained by combining flux-limited Sloan Digital Sky Survey optical and Wide field Infrared Survey Explorer mid-infrared data. We apply methods developed in previous works to access the intrinsic population distributions non-parametrically, taking into account the truncations and correlations inherent in the data. We find that the population of quasars exhibits positive luminosity evolution with redshift in the mid-infrared, but with considerably less mid-infrared evolution than in the optical or radio bands. With the luminosity evolutions accounted for, we determine the density evolution and local mid-infrared luminosity function. The latter displays a sharp flattening at local luminosities below $\\sim 10^{31}$ erg sec$^{-1}$ Hz$^{-1}$, which has been reported previously at 15 $\\mu$m for AGN classified as both type-1 and type-2. We calculate the integrated total emission from quasars at 2...

  11. AGN BLR structure, luminosity and mass from combined reverberation mapping and optical interferometry observations

    Science.gov (United States)

    Rakshit, Suvendu; Petrov, Romain G.

    2014-07-01

    Unveiling the structure of the Broad-Line Region (BLR) of AGN is critical to understand the quasar phenomenon. Detail study of the geometry and kinematic of these objects can answer the basic questions about the central BH mass, accretion mechanism and rate, growth and evolution history. Observing the response of the BLR clouds to continuum variations, Reverberation Mapping (RM) provides size-luminosity and mass-luminosity relations for QSOs and Sy1 AGNs with the goal to use these objects as standard candles and mass tags. However, the RM size can receive different interpretations depending on the assumed geometry and the corresponding mass depends on an unknown geometrical factor as well on the possible confusion between local and global velocity dispersion. From RM alone, the scatter around the mean mass is as large as a factor 3. Though BLRs are expected to be much smaller than the current spatial resolution of large optical interferometers (OI), we show that differential interferometry with AMBER, GRAVITY and successors can measure the size and constrain the geometry and kinematics on a large sample of QSOs and Sy1 AGNs. AMBER and GRAVITY (K_ 10:5) could be easily extended up to K= 13 by an external coherencer or by advanced "ncoherent" data processing. Future VLTI instrument could reach K~ 15. This opens a large AGN BLR program intended to obtain a very accurate calibration of mass, luminosity and distance measurements from RM data which will allow using many QSOs as standard candles and mass tags to study the general evolution of mass accretion in the Universe. This program is analyzed with our BLR model allowing predicting and interpreting RM and OI measures together and illustrated with the results of our observations of 3C273 with the VLTI.

  12. The many lives of AGN: cooling flows, black holes and the luminosities and colours of galaxies

    CERN Document Server

    Croton, D J; White, S D M; De Lucia, G; Frenk, C S; Gao, L; Jenkins, A; Kauffmann, G; Navarro, J F; Yoshida, N; Croton, Darren J.; Springel, Volker; White, Simon D. M.

    2006-01-01

    We simulate the growth of galaxies and their central supermassive black holes by implementing a suite of semi-analytic models on the output of the Millennium Run, a very large simulation of the concordance LCDM cosmogony. Our procedures follow the detailed assembly history of each object and are able to track the evolution of all galaxies more massive than the Small Magellanic Cloud throughout a volume comparable to that of large modern redshift surveys. In this first paper we supplement previous treatments of the growth and activity of central black holes with a new model for `radio' feedback from those AGN that lie at the centre of a quasistatic X-ray emitting atmosphere in a galaxy group or cluster. We show that for energetically and observationally plausible parameters such a model can simultaneously explain: (i) the low observed mass drop-out rate in cooling flows; (ii) the exponential cut-off at the bright end of the galaxy luminosity function; and (iii) the fact that the most massive galaxies tend to b...

  13. Revisiting the relationship between 6 {\\mu}m and 2-10 keV continuum luminosities of AGN

    CERN Document Server

    Mateos, S; Alonso-Herrero, A; Rovilos, E; Hernán-Caballero, A; Barcons, X; Blain, A; Caccianiga, A; Della Ceca, R; Severgnini, P

    2015-01-01

    We have determined the relation between the AGN luminosities at rest-frame 6 {\\mu}m associated to the dusty torus emission and at 2-10 keV energies using a complete, X-ray flux limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have X-ray luminosities corrected for intrinsic absorption between 10^42 and 10^46 erg/s and redshifts from 0.05 to 2.8. The rest-frame 6 {\\mu}m luminosities were computed using data from the Wide-Field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fit relationship for the full sample is consistent with being linear, L_6 {\\mu}m $\\propto$ L_2-10 keV^0.99$\\pm$0.032, but has significant intrinsic scatter, ~0.35 dex in log L_6 {\\mu}m. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have re...

  14. Revisiting the relationship between 6 {\\mu}m and 2-10 keV continuum luminosities of AGN

    OpenAIRE

    Mateos, S; Carrera, F. J.; Alonso-Herrero, A.; Rovilos, E.; Hernán-Caballero, A.; Barcons, X.; Blain, A.; Caccianiga, A.; R. Della Ceca(INAF, Oss. di Brera); Severgnini, P.

    2015-01-01

    We have determined the relation between the AGN luminosities at rest-frame 6 {\\mu}m associated to the dusty torus emission and at 2-10 keV energies using a complete, X-ray flux limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 10^42 and 10^46 erg/s and redshifts from 0.05 to 2.8. The rest-frame 6 {\\mu}m luminosities were computed using data from the Wide-Field Infrared Survey Explorer and are based on a spectral...

  15. Unveiling the physics of low luminosity AGN through X-ray variability: LINER versus Seyfert 2

    CERN Document Server

    Hernandez-Garcia, Lorena; Gonzalez-Martin, Omaira; Marquez, Isabel; Perea, Jaime

    2016-01-01

    X-ray variability is very common in active galactic nuclei (AGN), but these variations may not occur similarly in different families of AGN. We aim to disentangle the structure of low ionization nuclear emission line regions (LINERs) compared to Seyfert 2s by the study of their spectral properties and X-ray variations. We assembled the X-ray spectral parameters and variability patterns, which were obtained from simultaneous spectral fittings. Major differences are observed in the X-ray luminosities, and the Eddington ratios, which are higher in Seyfert 2s. Short-term X-ray variations were not detected, while long-term changes are common in LINERs and Seyfert 2s. Compton-thick sources generally do not show variations, most probably because the AGN is not accesible in the 0.5--10 keV energy band. The changes are mostly related with variations in the nuclear continuum, but other patterns of variability show that variations in the absorbers and at soft energies can be present in a few cases. We conclude that the ...

  16. Molecular gas around low-luminosity AGN in late-type spirals

    CERN Document Server

    Boeker, Torsten; Lisenfeld, Ute

    2011-01-01

    We have studied the molecular gas in the vicinity of low-luminosity active galactic nuclei (AGNs) in three bulge-less spiral galaxies: NGC 1042, NGC 4178, and NGC 4395. The (1-0) and (2-1) transitions of gaseous carbon monoxide (CO) are clearly detected within the central kpc of all three galaxies. In the case of NGC 4395, this constitutes the first reported detection of CO. In general, the CO emission is faint, as may be expected from their less-than-spectacular star formation activity. Interestingly, however, both face-on galaxies in our sample (which allow an unimpeded view of their nucleus) show an elevated intensity ratio CO(2-1)/CO(1-0) when compared to similar late-type spirals without an AGN. We discuss that this is unlikely due to a very compact CO source. Instead, we speculate that even energetically weak AGN can impact the physical state of the surrounding gas. We do not detect any tracers of dense molecular gas such as HCN or HCO+, but the sensitivity of our observations allows us to establish upp...

  17. X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku

    CERN Document Server

    Fioretti, V; Mushotzky, R F; Koss, M; Malaguti, G

    2013-01-01

    The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10^-11 erg cm^-2 s^-1 and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 100) X-to-[OIII] luminosity ratios, confirming the [OIII] luminosity to be affected by residual extinction in presence of mild absorption, especially for "buried" AGN such as 3C 452. Three of our targets are powerful FRII radio galaxies, making them the most luminous and absorbed AGN of the BAT Seyfert survey despite the inversely proportional N_H - L_X relation.

  18. AGN BLR structure, luminosity and mass from combined Reverberation Mapping and Optical Interferometry observations

    CERN Document Server

    Rakshit, Suvendu

    2014-01-01

    Unveiling the structure of the Broad Line Region (BLR) of AGN is critical to understand the quasar phenomenon. Detail study of the geometry and kinematic of these objects can answer the basic questions about the central BH mass, accretion mechanism and rate, growth and evolution history. Observing the response of the BLR clouds to continuum variations, Reverberation Mapping (RM) provides size vs luminosity and mass vs luminosity relations for QSOs and Sy1 AGNs with the goal to use these objects as standard candles and mass tags. However, the RM size can receive different interpretations depending on the assumed geometry and the corresponding mass depends on an unknown geometrical factor as well on the possible confusion between local and global velocity dispersion. From RM alone, the scatter around the mean mass is as large as a factor 3. Though BLRs are expected to be much smaller than the current spatial resolution of large optical interferometers (OI), we show that differential interferometry with AMBER, G...

  19. Systematic Biases in Galaxy Luminosity Functions

    OpenAIRE

    Dalcanton, Julianne J.

    1997-01-01

    Both the detection of galaxies and the derivation of the luminosity function depend upon isophotal magnitudes, implicitly in the first case, and explicitly in the latter. However, unlike perfect point sources, the fraction of a galaxy's light contained within the limiting isophote is a function of redshift, due to the combined effects of the point spread function and cosmological dimming. This redshift variation in the measured isophotal luminosity can strongly affect the derived luminosity f...

  20. Clustering of moderate luminosity X-ray-selected type 1 and type 2 AGNs at z ∼ 3

    Energy Technology Data Exchange (ETDEWEB)

    Allevato, V.; Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland); Civano, F. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Cappelluti, N. [University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Shankar, F. [Department of Physics and Astronomy, University of Southampton, Highfield SO17 1BJ (United Kingdom); Miyaji, T. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada (Mexico); Hasinger, G. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Gilli, R.; Zamorani, G.; Comastri, A. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Lanzuisi, G. [National Observatory of Athens I. Metaxa and Vas. Pavlou St. GR-15236 Penteli (Greece); Salvato, M. [Max-Planck-Institute für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Elvis, M. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Silverman, J. [Institute for the Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwashi, Chiba 277-8583 (Japan)

    2014-11-20

    We investigate, for the first time at z ∼ 3, the clustering properties of 189 Type 1 and 157 Type 2 X-ray active galactic nuclei (AGNs) of moderate luminosity ((L {sub bol}) = 10{sup 45.3} erg s{sup –1}), with photometric or spectroscopic redshifts in the range 2.2 < z < 6.8. These samples are based on Chandra and XMM-Newton data in COSMOS. We find that Type 1 and Type 2 COSMOS AGNs at z ∼ 3 inhabit DMHs with typical mass of log M{sub h} = 12.84{sub −0.11}{sup +0.10} and 11.73{sub −0.45}{sup +0.39} h {sup –1} M {sub ☉}, respectively. This result requires a drop in the halo masses of Type 1 and 2 COSMOS AGNs at z ∼ 3 compared to z ≲ 2 XMM-COSMOS AGNs with similar luminosities. Additionally, we infer that unobscured COSMOS AGNs at z ∼ 3 reside in 10 times more massive halos compared to obscured COSMOS AGNs, at the 2.6σ level. This result extends to z ∼ 3 the results found in COSMOS at z ≲ 2, and rules out the picture in which obscuration is purely an orientation effect. A model which assumes that the AGNs activity is triggered by major mergers is quite successful in predicting both the low halo mass of COSMOS AGNs and the typical mass of luminous SDSS quasars at z ∼ 3, with the latter inhabiting more massive halos respect to moderate luminosity AGNs. Alternatively we can argue, at least for Type 1 COSMOS AGNs, that they are possibly representative of an early phase of fast (i.e., Eddington limited) BH growth induced by cosmic cold flows or disk instabilities. Given the moderate luminosity, these new fast growing BHs have masses of ∼10{sup 7-8} M {sub ☉} at z ∼ 3 which might evolve into ∼10{sup 8.5-9} M {sub ☉} mass BHs at z = 0. Following our clustering measurements, we argue that this fast BH growth at z ∼ 3 in AGNs with moderate luminosity occurs in DMHs with typical mass of ∼ 6× 10{sup 12} h {sup –1} M {sub ☉}.

  1. THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2

    International Nuclear Information System (INIS)

    We present a study of the redshift evolution of the projected correlation function of 593 X-ray selected active galactic nuclei (AGNs) with IAB 2 XMM- Cosmic Evolution Survey (COSMOS). We introduce a method to estimate the average bias of the AGN sample and the mass of AGN hosting halos, solving the sample variance using the halo model and taking into account the growth of the structure over time. We find evidence of a redshift evolution of the bias factor for the total population of XMM-COSMOS AGNs from b-bar ( z-bar =0.92)=2.30±0.11 to b-bar ( z-bar =1.94)=4.37±0.27 with an average mass of the hosting dark matter (DM) halos log M0(h-1 Msun) ∼ 13.12 ± 0.12 that remains constant at all z 0(h-1 Msun) ∼ 13.28 ± 0.07 and log M0(h-1 Msun) ∼ 13.00 ± 0.06 for BL/X-ray unobscured AGNs and NL/X-ray obscured AGNs, respectively. The theoretical models, which assume a quasar phase triggered by major mergers, cannot reproduce the high bias factors and DM halo masses found for X-ray selected BL AGNs with LBOL ∼ 2 x 1045 erg s-1. Our work extends up to z ∼ 2.2 the z ∼< 1 statement that, for moderate-luminosity X-ray selected BL AGNs, the contribution from major mergers is outnumbered by other processes, possibly secular ones such as tidal disruptions or disk instabilities.

  2. AGN host galaxy mass function in COSMOS: is AGN feedback responsible for the mass-quenching of galaxies?

    CERN Document Server

    Bongiorno, A; Merloni, A; Zamorani, G; Ilbert, O; La Franca, F; Peng, Y; Piconcelli, E; Mainieri, V; Silverman, J D; Brusa, M; Fiore, F; Salvato, M; Scoville, N

    2016-01-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate i.e., lambda_SAR, distribution function (SARDF) up to z~2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best fit model characterizes the SARDF as a double power-law with mass dependent but redshift independent break whose low lambda_SAR slope flattens with increasing redshift while the normalization increases. This implies that, for a given stellar mass, higher lambda_SAR objects have a peak in their space density at earlier epoch compared to the lower lambda_SAR ones, following and mimicking the well known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schech...

  3. The Luminosity Function of Cluster Radio Relics

    OpenAIRE

    Bruggen, M.; Ensslin, T. A.; Miniati, F.

    2003-01-01

    In this paper we compute the luminosity function of radio relics. In our calculation we include only those relics that are produced by the compression of former radio cocoons. This compression is provided by shocks that are generated in the process of structure formation. Starting from an analytical model for the luminosity evolution of ageing radio cocoons, the luminosity function of radio galaxies and the statistics of shocks as inferred from cosmological simulations, we are able to make th...

  4. THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI: THE EFFECT OF HOST-GALAXY STARLIGHT ON LUMINOSITY MEASUREMENTS. II. THE FULL SAMPLE OF REVERBERATION-MAPPED AGNs

    International Nuclear Information System (INIS)

    We present high-resolution Hubble Space Telescope images of all 35 active galactic nuclei (AGNs) with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to ground-based spectroscopic luminosity measurements at 5100 A. After correcting the luminosities of the AGNs for the contribution from starlight, we re-examine the Hβ R BLR-L relationship. Our best fit for the relationship gives a power-law slope of 0.52 with a range of 0.45-0.59 allowed by the uncertainties. This is consistent with our previous findings, and thus still consistent with the naive assumption that all AGNs are simply luminosity-scaled versions of each other. We discuss various consistency checks relating to the galaxy modeling and starlight contributions, as well as possible systematic errors in the current set of reverberation measurements from which we determine the form of the R BLR-L relationship.

  5. Rest-frame UV single-epoch black hole mass estimates of low-luminosity AGN at intermediate redshifts

    OpenAIRE

    Karouzos, Marios; Woo, Jong-Hak; Matsuoka, Kenta; Kochanek, Christopher S.; Onken, Christopher A.; Kollmeier, Juna A.; Park, Dawoo; Nagao, Tohru; Kim, Sang Chul

    2015-01-01

    The ability to accurately derive black hole (BH) masses at progressively higher redshifts and over a wide range of continuum luminosities has become indispensable in the era of large-area extragalactic spectroscopic surveys. In this paper we present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts and luminosities comparable to the local H$\\beta$ reverberation mapped active galactic nuclei (AGN). We focus on the MgII, C...

  6. Revisiting Stochastic Variability of AGNs with Structure Functions

    CERN Document Server

    Kozłowski, Szymon

    2016-01-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to expectations from the damped random walk (DRW) model, generally well-describing the variability of active galactic nuclei (AGN), has triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ~9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the "sub-ensemble" SFs in the redshift-absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power-law (SPL; in the "red noise regime" after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at gamma=0.55+/-0.08 (0.52+/-0.06) and is consistent with DRW. There is a hint of a weak correlation of gamma with the luminosity and a lack of co...

  7. Revisiting Stochastic Variability of AGNs with Structure Functions

    Science.gov (United States)

    Kozłowski, Szymon

    2016-08-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to the expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs), have triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ∼9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the “subensemble” SFs in the redshift–absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power law (SPL; in the “red noise regime” after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at γ =0.55+/- 0.08 (0.52 ± 0.06) and is consistent with the DRW model. There is a hint of a weak correlation of γ with the luminosity and a lack of correlation with the black hole mass. The typical decorrelation timescale in the optical is τ =0.97+/- 0.46 year. The SF amplitude at one year obtained from the SPL fitting is {{SF}}0=0.22+/- 0.06 mag and is overestimated because the SF is already at the turnover part, so the true value is {{SF}}0=0.20+/- 0.06 mag. The asymptotic variability is {{SF}}∞ =0.25+/- 0.06 mag. It is strongly anticorrelated with both the luminosity and the Eddington ratio and is correlated with the black hole mass. The reliability of these results is fortified with Monte Carlo simulations.

  8. Clustering, Cosmology and a New Era of Black Hole Demographics -- II. The Conditional Luminosity Functions of Type 2 and Type 1 Active Galactic Nuclei

    CERN Document Server

    Ballantyne, D R

    2016-01-01

    The orientation-based unification model of active galactic nuclei (AGNs) posits that the principle difference between obscured (Type 2) and unobscured (Type 1) AGNs is the line-of-sight into the central engine. If this model is correct than there should be no difference in many of the properties of AGN host galaxies (e.g., the mass of the surrounding dark matter haloes). However, recent clustering analyses of Type 1 and Type 2 AGNs have provided some evidence for a difference in the halo mass, in conflict with the orientation-based unified model. In this work, a method to compute the Conditional Luminosity Function (CLF) of Type 2 and Type 1 AGNs is presented. The CLF allows many fundamental halo properties to be computed as a function of AGN luminosity, which we apply to the question of the host halo masses of Type 1 and 2 AGNs. By making use of the total AGN CLF, the Type 1 X-ray luminosity function, and the luminosity-dependent Type 2 AGN fraction, the CLFs of Type 1 and 2 AGNs are calculated at $z\\approx ...

  9. The Luminosity Function of Cluster Radio Relics

    CERN Document Server

    Brüggen, M; Miniati, F

    2003-01-01

    In this paper we compute the luminosity function of radio relics. In our calculation we include only those relics that are produced by the compression of former radio cocoons. This compression is provided by shocks that are generated in the process of structure formation. Starting from an analytical model for the luminosity evolution of ageing radio cocoons, the luminosity function of radio galaxies and the statistics of shocks as inferred from cosmological simulations, we are able to make the first estimates of the brightness distribution of radio relics. The computed luminosity function is consistent with current observations and predicts that more than $10^3$ radio relics should be discovered with the upcoming generation of low-frequency radio telescopes. Moreover, we predict that radio relics are predominantly found in low-pressure regions outside the cores of clusters.

  10. Iron K Line Variability in the Low-Luminosity AGN NGC 4579

    Science.gov (United States)

    Terashima, Yuichi; Ho, Luis C.; Ptak, Andrew F.; Yaqoob, Tahir; Kunieda, Hideyo; Misaki, Kazutami; Serlemitsos, Peter J.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    We present results of new ASCA observations of the low-luminosity AGN (LLAGN) NGC 4579 obtained in 1998 December 18 and 28, and we report on detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical, L(sub X) approximately = 2 x 10(exp 4l) ergs/s, but they are approximately 35% larger than that measured in 1995 July by Terashima et al. (1998). An Fe K emission line is detected at 6.39 +/- 0.09 keV (source rest frame) which is lower than the line energy 6.73(sup +0.13, sub -0.12) keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.4 keV and 6.73 KeV, the intensity of the 6.7 keV line decreased, while the intensity of the 6.4 keV line increased, within an interval of 3.5 years. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line suggest that an optically thick standard accretion disk is present and subtends a large solid angle viewed from the nucleus at the Eddington ratio of L(sub Bol)/L(sub Eddington) approximately 2 x 10(exp -3) (Ho 1999). A broad disk-line profile is not clearly seen and the structure of the innermost part of accretion disk remains unclear.

  11. X-ray View of Four High-Luminosity Swift-BAT AGN: Unveiling Obscuration and Reflection with Suzaku

    Science.gov (United States)

    Fiorettil, V.; Angelini, L.; Mushotzky, R. F.; Koss, M.; Malaguti, G.

    2013-01-01

    Aims. A complete census of obscured Active Galactic Nuclei (AGN) is necessary to reveal the history of the super massive black hole (SMBH) growth and galaxy evolution in the Universe given the complex feedback processes and the fact that much of this growth occurs in an obscured phase. In this context, hard X-ray surveys and dedicated follow-up observations represent a unique tool for selecting highly absorbed AGN and for characterizing the obscuring matter surrounding the SMBH. Here we focus on the absorption and reflection occurring in highly luminous, quasar-like AGN, to study the relation between the geometry of the absorbing matter and the AGN nature (e.g. X-ray, optical, and radio properties), and to help to determine the column density dependency on the AGN luminosity. Methods. The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10(exp -11) erg per square centimeter and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 less than LogLBAT less than 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis, adding an original spectral analysis when non was available from the literature. Results. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption (N(sub H) approximately 4 × 10(exp 23) per square centimeter) and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (less than 0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density

  12. Infrared Classification and Luminosities For Dusty AGN and the Most Luminous Quasars

    OpenAIRE

    Weedman, Daniel; Sargsyan, Lusine; Lebouteiller, Vianney; Houck, James; Barry, Donald

    2012-01-01

    Mid-infrared spectroscopic measurements from the Infrared Spectrometer on Spitzer (IRS) are given for 125 hard X-ray AGN (14-195 keV) from the Swift Burst Alert Telescope sample and for 32 AGN with black hole masses from reverberation mapping. The 9.7 um silicate feature in emission or absorption defines an infrared AGN classification describing whether AGN are observed through dust clouds, indicating that 55% of the BAT AGN are observed through dust. The mid-infrared dust continuum luminosit...

  13. The clustering amplitude of X-ray selected AGN at z=0.8: Evidence for a negative dependence on accretion luminosity

    CERN Document Server

    Mountrichas, G; Menzel, M L; Fanidakis, N; Merloni, A; Liu, Z; Salvato, M; Nandra, K

    2016-01-01

    The northern tile of the wide-area and shallow XMM-XXL X-ray survey field is used to estimate the average dark matter halo mass of relatively luminous X-ray selected AGN [$\\rm log\\, L_X (\\rm 2-10\\,keV)= 43.6^{+0.4}_{-0.4}\\,erg/s$] in the redshift interval $z=0.5-1.2$. Spectroscopic follow-up observations of X-ray sources in the XMM-XXL field by the Sloan telescope are combined with the VIPERS spectroscopic galaxy survey to determine the cross-correlation signal between X-ray selected AGN (total of 318) and galaxies (about 20,\\,000). We model the large scales (2-25\\,Mpc) of the correlation function to infer a mean dark matter halo mass of $\\log M / (M_{\\odot} \\, h^{-1}) = 12.50 ^{+0.22} _{-0.30}$ for the X-ray selected AGN sample. This measurement is about 0.5\\,dex lower compared to estimates in the literature of the mean dark matter halo masses of moderate luminosity X-ray AGN [$L_X (\\rm 2-10\\,keV)\\approx 10^{42} - 10^{43}\\,erg/s$] at similar redshifts. Our analysis also links the mean clustering properties o...

  14. The dependence of the soft X ray spectral slope with radio property, luminosity, and redshift, for a large sample of AGN from the Einstein IPC data base

    Science.gov (United States)

    Brunner, H.; Worrall, D. M.; Wilkes, Belinda J.; Elvis, Martin

    1989-01-01

    The dependence of the soft X-ray spectral slope on radio, optical and X-ray properties, and on redshift are reported for a large sample of Active Galactic Nuclei (AGN). The sample includes 317 optically and radio-selected AGN from a preliminary version of the Einstein Imaging Proportional Counter (IPC) quasar and AGN data base. The main results are: the difference in X-ray slope between radio-loud and radio-quiet AGN were confirmed for an independent and much larger sample of sources; a difference in X-ray slope between flat and steep radio spectrum AGN is observed only in high luminosity sub-sample; in flat radio spectrum AGNs there is an indication for a dependence of the X-ray spectral index on X-ray luminosity redshift and alpha sub 0x.

  15. Detailed Shape and Evolutionary Behavior of the X-ray Luminosity Function of Active Galactic Nuclei

    CERN Document Server

    Miyaji, T; Salvato, M; Brusa, M; Cappelluti, N; Civano, F; Puccetti, S; Elvis, M; Brunner, H; Fotopoulou, S; Ueda, Y; Griffiths, R E; Koekemoer, A M; Akiyama, M; Comastri, A; Gilli, R; Lanzuisi, G; Merloni, A; Vignali, C

    2015-01-01

    We construct the rest-frame 2--10 keV intrinsic X-ray luminosity function of Active Galactic Nuclei (AGNs) from a combination of X-ray surveys from the all-sky Swift BAT survey to the Chandra Deep Field-South. We use ~3200 AGNs in our analysis, which covers six orders of magnitude in flux. The inclusion of the XMM and Chandra COSMOS data has allowed us to investigate the detailed behavior of the XLF and evolution. In deriving our XLF, we take into account realistic AGN spectrum templates, absorption corrections, and probability density distributions in photometric redshift. We present an analytical expression for the overall behavior of the XLF in terms of the luminosity-dependent density evolution, smoothed two power-law expressions in 11 redshift shells, three-segment power-law expression of the number density evolution in four luminosity classes, and binned XLF. We observe a sudden flattening of the low luminosity end slope of the XLF slope at z>~0.6. Detailed structures of the AGN downsizing have been als...

  16. X-ray Variability as a Probe of Advection-Dominated Accretion in Low-Luminosity AGN

    OpenAIRE

    Ptak, A.; Yaqoob, T.; Mushotzky, R.; Serlemitsos, P.; Griffiths, R.

    1998-01-01

    As a class, LINERs and Low-Luminosity AGN tend to show little or no significant short-term variability (i.e., with time-scales less than a day). This is a marked break for the trend of increased variability in Seyfert 1 galaxies with decreased luminosity. We propose that this difference is due to the lower accretion rate in LINERs and LLAGN which is probably causing the accretion flow to be advection-dominated. This results in a larger characteristic size for the X-ray producing region than i...

  17. Low-Luminosity AGN as analogues of Galactic Black Holes in the low/hard state: Evidence from X-ray timing of NGC 4258

    CERN Document Server

    Markowitz, A

    2005-01-01

    We present a broadband power spectral density function (PSD) measured from extensive RXTE monitoring data of the low-luminosity AGN NGC 4258, which has an accurate, maser-determined black hole mass of 3.9+/-0.1 * 10^7 solar masses. We constrain the PSD break timescale to be greater than 4.5 d at >90% confidence, which appears to rule out the possibility that NGC 4258 is an analogue of black hole X-ray binaries (BHXRBs) in the high/soft state. In this sense, the PSD of NGC 4258 is different to those of some more-luminous Seyferts, which appear similar to the PSDs of high/soft state X-ray binaries. This result supports previous analogies between LLAGN and X-ray binaries in the low/hard state based on spectral energy distributions, indicating that the AGN/BHXRB analogy is valid across a broad range of accretion rates.

  18. Radio luminosity function of brightest cluster galaxies

    CERN Document Server

    Yuan, Z S; Wen, Z L

    2016-01-01

    By cross-matching the currently largest optical catalog of galaxy clusters and the NVSS radio survey database, we obtain the largest complete sample of brightest cluster galaxies (BCGs) in the redshift range of 0.05luminosity functions of BCGs from the largest complete sample of BCGs, and find that the functions depend on the optical luminosity of BCGs and the dynamical state of galaxy clusters. However, the radio luminosity function does not show significant evolution with redshift.

  19. STELLAR VELOCITY DISPERSION MEASUREMENTS IN HIGH-LUMINOSITY QUASAR HOSTS AND IMPLICATIONS FOR THE AGN BLACK HOLE MASS SCALE

    International Nuclear Information System (INIS)

    We present new stellar velocity dispersion measurements for four luminous quasars with the Near-Infrared Integral Field Spectrometer instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8 m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole (BH) masses in luminous quasars are necessary to investigate the coevolution of BHs and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass BHs are not offset with respect to the MBH-σ* relation exhibited by lower-luminosity active galactic nuclei (AGNs) with lower-mass BHs, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor (f) that places the reverberation data on the quiescent MBH-σ* relation. With our updated measurements and new additions to the AGN sample, we obtain (f) = 4.31 ± 1.05, which is slightly lower than, but consistent with, most previous determinations

  20. STELLAR VELOCITY DISPERSION MEASUREMENTS IN HIGH-LUMINOSITY QUASAR HOSTS AND IMPLICATIONS FOR THE AGN BLACK HOLE MASS SCALE

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Martini, P.; Peterson, B. M.; Pogge, R. W.; Zu, Y. [Department of Astronomy, Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States); Watson, L. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Dasyra, K. M. [Observatoire de Paris, LERMA (CNRS:UMR8112), 61 Avenue de l' Observatoire, F-75014, Paris (France); Dietrich, M. [Department of Physics and Astronomy, Ohio University, Athens, OH 45601 (United States); Ferrarese, L. [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria BV V9E 2E7 (Canada)

    2013-08-20

    We present new stellar velocity dispersion measurements for four luminous quasars with the Near-Infrared Integral Field Spectrometer instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8 m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole (BH) masses in luminous quasars are necessary to investigate the coevolution of BHs and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass BHs are not offset with respect to the M{sub BH}-{sigma}{sub *} relation exhibited by lower-luminosity active galactic nuclei (AGNs) with lower-mass BHs, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor (f) that places the reverberation data on the quiescent M{sub BH}-{sigma}{sub *} relation. With our updated measurements and new additions to the AGN sample, we obtain (f) = 4.31 {+-} 1.05, which is slightly lower than, but consistent with, most previous determinations.

  1. Stellar Velocity Dispersion Measurements in High-Luminosity Quasar Hosts and Implications for the AGN Black Hole Mass Scale

    CERN Document Server

    Grier, C J; Watson, L C; Peterson, B M; Bentz, M C; Dasyra, K M; Dietrich, M; Ferrarese, L; Pogge, R W; Zu, Y

    2013-01-01

    We present new stellar velocity dispersion measurements for four luminous quasars with the NIFS instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8-m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole masses in luminous quasars are necessary to investigate the coevolution of black holes and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass black holes are not offset with respect to the MBH-sigma relation exhibited by lower-luminosity AGNs with lower-mass black holes, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor hfi that places the reverberation data on the quiescent M_BH-sigma relation. With our updated measurements and new additions to the AGN sample, we obtain = 4...

  2. The Star Formation and AGN luminosity relation: Predictions from a semi-analytical model

    OpenAIRE

    Gutcke, T. A.; Fanidakis, N.; Macciò, A.V; Lacey, C. G.

    2015-01-01

    In a universe where active galactic nucleus (AGN) feedback regulates star formation in massive galaxies, a strong correlation between these two quantities is expected. If the gas causing star formation is also responsible for feeding the central black hole, then a positive correlation is expected. If powerful AGNs are responsible for the star formation quenching, then a negative correlation is expected. Observations so far have mainly found a mild correlation or no correlation at all [i.e. a ...

  3. X-ray long-term variations in the low-luminosity AGN NGC835 and its circumnuclear emission

    CERN Document Server

    Gonzalez-Martin, O; Masegosa, J; Marquez, I; Rodriguez-Espinosa, J M; Acosta-Pulido, J A; Alonso-Herrero, A; Arredondo, D Esparza

    2015-01-01

    Obscured active galactic nuclei (AGNs) are thought to be very common in the Universe. Observations and surveys have shown that the number of sources increases for near galaxies and at the low-luminosity regime (the so-called LLAGNs). Furthermore, many AGNs show changes in their obscuration properties at X-rays that may suggest a configuration of clouds very close to the accretion disk. However, these variations could also be due to changes in the intrinsic continuum of the source. It is therefore important to study nearby AGN to better understand the locus and distribution of clouds in the neighbourhood of the nucleus. We aim to study the nuclear obscuration of LLAGN NGC835 and its extended emission using mid-infrared observations. We present mid-infrared 11.5 microns imaging of the LLAGN galaxy NGC835 obtained with the instrument CanariCam in the Gran Telescopio CANARIAS (GTC), archival Spitzer/IRS spectroscopy, and archival Chandra data observed in 2000, 2008, and 2013. The GTC/CanariCam 11.5 microns image ...

  4. Rest-frame UV single-epoch black hole mass estimates of low-luminosity AGN at intermediate redshifts

    CERN Document Server

    Karouzos, Marios; Matsuoka, Kenta; Kochanek, Christopher S; Onken, Christopher A; Kollmeier, Juna A; Park, Dawoo; Nagao, Tohru; Kim, Sang Chul

    2015-01-01

    The ability to accurately derive black hole (BH) masses at progressively higher redshifts and over a wide range of continuum luminosities has become indispensable in the era of large-area extragalactic spectroscopic surveys. In this paper we present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts and luminosities comparable to the local H$\\beta$ reverberation mapped active galactic nuclei (AGN). We focus on the MgII, CIV, and CIII] broad emission lines and compare them to both H$\\alpha$ and H$\\beta$. We use newly acquired near-infrared spectra from the FMOS instrument on the Subaru telescope for 89 broad-lined AGN at redshifts between 0.3 and 3.5, complemented by data from the AGES survey. We employ two different prescriptions for measuring the emission line widths and compare the results. We confirm that MgII shows a tight correlation with H$\\alpha$ and H$\\beta$, with a scatter of ~0.25 dex. The CIV and CIII] estimators, while showing...

  5. Radio-Variability in Radio-Quiet Quasars and Low-Luminosity AGN

    OpenAIRE

    Falcke, Heino; Lehar, Joseph; Barvainis, Richard; Nagar, Neil M.; Wilson, Andrew S.

    2000-01-01

    We report on two surveys of radio-weak AGN to look for radio variability. We find significant variability with an RMS of 10-20% on a timescale of months in radio-quiet and radio-intermediate quasars. This exceeds the variability of radio cores in radio-loud quasars (excluding blazars), which vary only on a few percent level. The variability in radio-quiet quasars confirms that the radio emission in these sources is indeed related to the AGN. The most extremely variable source is the radio-int...

  6. The XMM-Newton Serendipitous Survey. VI. The X-ray Luminosity Function

    CERN Document Server

    Ebrero, J; Page, M J; Silverman, J D; Barcons, X; Ceballos, M T; Corral, A; Della Ceca, R; Watson, M G

    2008-01-01

    We present the X-ray luminosity function of AGN in three energy bands (Soft: 0.5-2 keV, Hard: 2-10 keV and Ultrahard: 4.5-7.5 keV). We have used the XMS survey along with other highly complete flux-limited deeper and shallower surveys for a total of 1009, 435 and 119 sources in the Soft, Hard and Ultrahard bands, respectively. We have modeled the intrinsic absorption of the Hard and Ultrahard sources (NH function) and computed the intrinsic X-ray luminosity function in all bands using a Maximum Likelihood fit technique to an analytical model. We find that the X-ray luminosity function (XLF) is best described by a Luminosity-Dependent Density Evolution (LDDE) model. Our results show a good overall agreement with previous results in the Hard band, although with slightly weaker evolution. Our model in the Soft band present slight discrepancies with other works in this band, the shape of our present day XLF being significantly flatter. We find faster evolution in the AGN detected in the Ultrahard band than those ...

  7. Galaxy Luminosity Functions in WINGS clusters

    CERN Document Server

    Moretti, A; Poggianti, B M; Fasano, G; Varela, J; D'Onofrio, M; Vulcani, B; Cava, A; Fritz, J; Couch, W J; Moles, M; Kjærgaard, P

    2015-01-01

    Using V band photometry of the WINGS survey, we derive galaxy luminosity functions (LF) in nearby clusters. This sample is complete down to Mv=-15.15, and it is homogeneous, thus allowing the study of an unbiased sample of clusters with different characteristics. We constructed the photometric LF for 72 out of the original 76 WINGS clusters, excluding only those without a velocity dispersion estimate. For each cluster we obtained the LF for galaxies in a region of radius=0.5 x r200, and fitted them with single and double Schechter's functions. We also derive the composite LF for the entire sample, and those pertaining to different morphological classes. Finally we derive the spectroscopic cumulative LF for 2009 galaxies that are cluster members. The double Schechter fit parameters are neither correlated with the cluster velocity dispersion, nor with the X-ray luminosity. Our median values of the Schechter's fit slope are, on average, in agreement with measurements of nearby clusters, but are less steep that t...

  8. The Mid-IR and X-ray Selected QSO Luminosity Function

    CERN Document Server

    Assef, R J; Ashby, M L N; Brodwin, M; Brown, M J I; Cool, R; Forman, W; Gonzalez, A H; Hickox, R C; Jannuzi, B T; Jones, C; Le Floc'h, E; Moustakas, J; Murray, S S; Stern, D

    2010-01-01

    We present the J-band luminosity function of 1838 mid-infrared and X-ray selected AGNs in the redshift range 03 we observe a decrease in the space density of quasars of all brightnesses. We model the luminosity function by a double power-law and find that its evolution cannot be described by either pure luminosity or pure density evolution, but must be a combination of both. Our best-fit model has bright and faint power-law indices consistent with the low redshift measurements based on the 2QZ and 2SLAQ surveys and it generally agrees with the number of bright quasars predicted by other LFs at all redshifts. If we construct the QSO luminosity function using only the IRAC-selected AGNs, we find that the biases inherent to this selection method significantly modify the behavior of phi*(z) only for z<1 and have no significant impact upon the characteristic magnitude M*_J(z).

  9. NLC Luminosity as a Function of Beam Parameters

    CERN Document Server

    Nosochkov, Yu M; Raubenheimer, T O; Seryi, Andrei

    2002-01-01

    Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.

  10. Unveiling the Physics of Low-luminosity AGNs through X-Ray Variability: LINER versus Seyfert 2

    Science.gov (United States)

    Hernández-García, L.; Masegosa, J.; González-Martín, O.; Márquez, I.; Perea, J.

    2016-06-01

    X-ray variability is very common in active galactic nuclei (AGNs), but these variations may not occur similarly in different families of AGNs. We aim to disentangle the structure of low-ionization nuclear emission-line regions (LINERs) compared to Seyfert 2s by the study of their spectral properties and X-ray variations. We assembled the X-ray spectral parameters and variability patterns, which were obtained from simultaneous spectral fittings. Major differences are observed in the X-ray luminosities and the Eddington ratios, which are higher in Seyfert 2s. Short-term X-ray variations were not detected, while long-term changes are common in LINERs and Seyfert 2s. Compton-thick sources generally do not show variations, most probably because the AGN is not accesible in the 0.5–10 keV energy band. The changes are mostly related to variations in the nuclear continuum, but other patterns of variability show that variations in the absorbers and at soft energies can be present in a few cases. We conclude that the X-ray variations may occur similarly in LINERs and Seyfert 2s, i.e., they are related to the nuclear continuum, although they might have different accretion mechanisms. Variations at UV frequencies are detected in LINER nuclei but not in Seyfert 2s. This is suggestive of at least some LINERs having an unobstructed view of the inner disk where the UV emission might take place, with UV variations being common in them. This result might be compatible with the disappeareance of the torus and/or the broad-line region in at least some LINERs.

  11. Sleeping Giants? - X-ray search for low-luminosity AGN candidates in nearby optically bright galaxies

    CERN Document Server

    Kalcheva, Ivayla E

    2014-01-01

    In this Master's project, the X-ray nuclear properties of a sample of bright nearby galaxies are explored. This is done by matching their comprehensive optical spectroscopic classification to the latest available XMM-Newton catalogue - 3XMM-DR4. The good coverage (approx. 38 per cent) ensures that a statistically representative sample is investigated. All nuclear and morphological subsets found within the original sample of 486 galaxies are encompassed, but early-type galaxies and galaxies with optical features characteristic for active galactic nuclei (AGN) are favoured. The results from the investigation of the properties of our cross-matched sample are overall consistent with the presence of a large fraction of X-ray - detected low-luminosity AGN (LLAGN). The X-ray - detected galaxies within our HII and transition-LINER subsets are of particular interest, as they could harbour LLAGN missed by optical spectroscopic selection. The properties of these nuclei are explored by X-ray spectral fitting of available...

  12. The Suzaku view of highly-ionised outflows in AGN: II -- Location, energetics and scalings with Bolometric Luminosity

    CERN Document Server

    Gofford, J; McLaughlin, D E; Braito, V; Turner, T J; Tombesi, F; Cappi, M

    2015-01-01

    Ongoing studies with XMM-Newton have shown that powerful accretion disc winds, as revealed through highly-ionised Fe\\,K-shell absorption at E>=6.7 keV, are present in a significant fraction of Active Galactic Nuclei (AGN) in the local Universe (Tombesi et al. 2010). In Gofford et al. (2013) we analysed a sample of 51 Suzaku-observed AGN and independently detected Fe K absorption in ~40% of the sample, and we measured the properties of the absorbing gas. In this work we build upon these results to consider the properties of the associated wind. On average, the fast winds (v_out>0.01c) are located ~10^{15-18} cm (typically ~10^{2-4} r_s) from their black hole, their mass outflow rates are of the order ~0.01-1 Msun/yr or ~(0.01-1) M_edd and kinetic power is constrained to ~10^{43-45} erg/s, equivalent to ~(0.1-10%) L_edd. We find a fundamental correlation between the source bolometric luminosity and the wind velocity, with v_out \\propto L_bol^{\\alpha} and \\alpha=0.4^{+0.3}_{-0.2}$ (90% confidence), which indica...

  13. Extending Virial Black Hole Mass Estimates to Low-Luminosity or Obscured AGN: the cases of NGC 4395 and MCG -01-24-012

    CERN Document Server

    La Franca, F; Ricci, F; Sani, E; Brusa, M; Maiolino, R; Fiore, F; Marconi, A; Vignali, C

    2015-01-01

    In the last decade, using single epoch (SE) virial based spectroscopic optical observations, it has been possible to measure the black hole (BH) mass on large type 1 Active Galactic Nuclei (AGN) samples. However this kind of measurements can not be applied on those obscured type 2 and/or low luminosity AGN where the nuclear component does not dominate in the optical. We have derived new SE relationships, based on the FWHM and luminosity of the broad line region component of the Pabeta emission line and/or the hard X-ray luminosity in the 14-195 keV band, which have the prospect of better working with low luminosity or obscured AGN. The SE relationships have been calibrated in the 10^5-10^9 M_sol mass range, using a sample of AGN whose BH masses have been previously measured using reverberation mapping techniques. Our tightest relationship between the reverberation-based BH mass and the SE virial product has an intrinsic spread of 0.20 dex. Thanks to these SE relations, in agreement with previous estimates, we...

  14. The Luminosity and Stellar Mass Functions of Red W1-W2 Galaxies

    CERN Document Server

    O'Connor, Jessica A; Satyapal, Shobita; Secrest, Nathan J

    2016-01-01

    We present a study of nearby galaxies as a function of their [3.4]-[4.6] colour. Galaxies that are red in their [3.4]-[4.6] colour contain heated dust and the reddest systems ([3.4]-[4.6] > 0.5) are classified as AGN by some selection criteria. The sample discussed here includes nearby galaxies selected from the Sloan Digital Sky Survey (SDSS) that are also in the Wide-field Infrared Survey Explorer (WISE) catalogue. We calculate the number density of galaxies, in the form of the luminosity and mass functions, using the V/Vmax method and a Stepwise Maximum Likelihood method that has been modified to account for the additional colour selection. The reddest galaxies which have [3.4]-[4.6] > 0.8 and are sometimes classified as AGN by their colour, make up 0.2% of nearby galaxies. However, the reddest galaxies are a rising fraction of the low mass galaxy population. Identifying the lowest mass (M 0.8) galaxies as AGN is surprising given that none are optical AGN or composites, in contrast with their more massive...

  15. Radio spectra and radio-loudness of low-luminosity AGNs

    International Nuclear Information System (INIS)

    We investigated the empirical relation between black hole mass (mBH), Eddington ratio (Lbol/LEdd), and radio loudness (RRL a ratio of radio to optical luminosity) of nearby low-luminosity active galactic nuclei (LLAGNs). A best-fit plane was found in the three-dimensional space using a sample of 48 nearby LLAGNs: RRL mBH0.52±0.l4(Lbol/LEdd)-0.39±0.08. This suggests that spectral energy distributions of LLAGNs are controlled by both the black hole mass and accretion rate

  16. THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: THE QUASAR LUMINOSITY FUNCTION FROM DATA RELEASE NINE

    International Nuclear Information System (INIS)

    We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22,301 i ∼2, with confirmed spectroscopic redshifts between 2.2 i (z = 2.2) ≈ –24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log Φ* – M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of ∼2.6 while Φ* declines by a factor of ∼8. At z ∼< 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of ''AGN downsizing'' is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities

  17. SurveySim: a new MCMC code to explore the evolution of the IR luminosity function

    Science.gov (United States)

    Bonato, Matteo; Kurinsky, Noah; Sajina, Anna; Kirkpatrick, Allison; Pope, Alexandra; Silva, Andrea; Yan, Lin

    2016-01-01

    The Herschel and Spitzer space telescopes have been crucial in furthering our understanding of the formation and evolution of galaxies. However key questions, such as the role of SF and AGN in powering the IR output of galaxies remain unanswered. The large numbers of high redshift galaxies detected by recent IR surveys make individual spectroscopic follow-up impractical. However statistical trends in SED and luminosity function evolution in an entire population can be realized. We present a new open source Markov-Chain Monte Carlo code, SurveySim. It is built to constrain the spectral energy distribution and luminosity function evolution required to produce a given multi-wavelength survey. Its very general design allow us to use a wide range of different dusty galaxy populations (including SFGs, AGNs and Composites), luminosity function forms and SED templates. The code employs a multidimensional color-color diagnostic to determine goodness of fit. It simulates observational errors and takes into account incompleteness. Here, dusty high-z galaxies at different parts of the IR SED have been considered to analyze the relative selection biases.

  18. Luminosity function of clusters of galaxies

    CERN Document Server

    Paolillo, M; Longo, G; Puddu, E; Gal, R R; Scaramella, R; Djorgovski, S G; De Carvalho, R

    2001-01-01

    The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to control fields. Due to the wide field coverage of the digitised POSS-II plates, we can measure field counts around each cluster in a fully homogeneous way. Furthermore, the availability of virtually unlimited sky coverage allows us to directly compute the LF errors without having to rely on the estimated variance of the background. The wide field coverage also allows us to derive the LF of the whole cluster, including galaxies located in the cluster outskirts. The global composite LF has a slope alpha ~ -1.1+/-0.2 with minor variations from blue to red filters, and M* ~ -21.7,-22.2,-22.4 mag (H_0=50 km/s/Mpc) in g, r and i filters, respectively. These results are in quite good agreement with several previous determinations and in particular with the LF determined for the inner region of a largely overlapping set of clu...

  19. Radio spectra and radio-loudness of low-luminosity AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Akihiro [Faculty of Science, Yamaguchi University, 1667-1 Yoshida, Yamaguchi, Yamaguchi 753-8512 (Japan); Kameno, Seiji [Faculty of Science, Kagoshima University, 1-21-30 Korimoto, Kagoshima, Kagoshima 890-0065 (Japan); Inoue, Makoto [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2006-12-15

    We investigated the empirical relation between black hole mass (m{sub BH}), Eddington ratio (L{sub bol}/L{sub Edd}), and radio loudness (R{sub RL} a ratio of radio to optical luminosity) of nearby low-luminosity active galactic nuclei (LLAGNs). A best-fit plane was found in the three-dimensional space using a sample of 48 nearby LLAGNs: R{sub RL} m{sub BH}{sup 0.52{+-}}{sup 0.l4}(L{sub bol}/L{sub Edd}){sup -0.39{+-}}{sup 0.08}. This suggests that spectral energy distributions of LLAGNs are controlled by both the black hole mass and accretion rate.

  20. Variability-selected low luminosity AGNs in the SA57 and in the CDFS

    CERN Document Server

    Vagnetti, F; Trevese, D

    2009-01-01

    Low Luminosity Active Galactic Nuclei (LLAGNs) are contaminated by the light of their host galaxies, thus they cannot be detected by the usual colour techniques. For this reason their evolution in cosmic time is poorly known. Variability is a property shared by virtually all active galactic nuclei, and it was adopted as a criterion to select them using multi epoch surveys. Here we report on two variability surveys in different sky areas, the Selected Area 57 and the Chandra Deep Field South.

  1. THE MID-IR- AND X-RAY-SELECTED QSO LUMINOSITY FUNCTION

    International Nuclear Information System (INIS)

    We present the J-band luminosity function (LF) of 1838 mid-infrared and X-ray-selected active galactic nuclei (AGNs) in the redshift range 0 3, we observe a decrease in the space density of quasars of all brightnesses. We model the LF by a double power law and find that its evolution cannot be described by either pure luminosity or pure density evolution, but must be a combination of both. We used the bright-end slope determined by Croom et al. (2QZ) as a prior to fit the data in order to minimize the effects of our small survey area. The bright-end power-law index of our best-fit model remains consistent with the prior, while the best-fit faint-end index is consistent with the low-redshift measurements based on the 2QZ and 2SLAQ surveys. Our best-fit model generally agrees with the number of bright quasars predicted by other LFs at all redshifts. If we construct the QSO luminosity function using only the IRAC-selected AGNs, we find that the biases inherent to this selection method significantly modify the behavior of the characteristic density φ*(z) only for z *,J(z).

  2. The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster

    CERN Document Server

    Miller, Neal A; Mobasher, Bahram; Bridges, Terry J; Hudson, Michael J; Marzke, Ronald O; Smith, Russell J

    2009-01-01

    We investigate the radio luminosity function (RLF) and radio source population for two fields within the Coma cluster of galaxies. Our VLA data reach down to log(L) = 20.23 W/Hz for Coma, and we associate 249 sources with optical counterparts from the SDSS. Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between AGN and star-forming galaxies (SFG). The radio-detected SFG are the dominant population only for ~21 ~ 22.48 W/Hz) and low (log(L) <~ 21 W/Hz) ends. Through a stacking analysis of these optically-bright ellipticals we find that they continue to harbor radio sources down to log(L) = 19.48. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (Mr ~ -14) dw arf ellipticals hosting strong radio AGN.

  3. DECOMPOSING STAR FORMATION AND ACTIVE GALACTIC NUCLEUS WITH SPITZER MID-INFRARED SPECTRA: LUMINOSITY FUNCTIONS AND CO-EVOLUTION

    International Nuclear Information System (INIS)

    We present Spitzer 7-38 μm spectra for a 24 μm flux-limited sample of galaxies at z ∼ 0.7 in the COSMOS field. The detailed high-quality spectra allow us to cleanly separate star formation (SF) and active galactic nucleus (AGN) in individual galaxies. We first decompose mid-infrared luminosity functions (LFs). We find that the SF 8 μm and 15 μm LFs are well described by Schechter functions. AGNs dominate the space density at high luminosities, which leads to the shallow bright-end slope of the overall mid-infrared LFs. The total infrared (8-1000 μm) LF from 70 μm selected galaxies shows a shallower bright-end slope than the bolometrically corrected SF 15 μm LF, owing to the intrinsic dispersion in the mid-to-far-infrared spectral energy distributions. We then study the contemporary growth of galaxies and their supermassive black holes (BHs). Seven of the thirty-one luminous infrared galaxies with Spitzer spectra host luminous AGNs, implying an AGN duty cycle of 23% ± 9%. The time-averaged ratio of BH accretion rate and SF rate matches the local MBH - Mbulge relation and the MBH - Mhost relation at z ∼ 1. These results favor co-evolution scenarios in which BH growth and intense SF happen in the same event but the former spans a shorter lifetime than the latter. Finally, we compare our mid-infrared spectroscopic selection with other AGN identification methods and discuss candidate Compton-thick AGNs in the sample. While only half of the mid-infrared spectroscopically selected AGNs are detected in X-ray, ∼90% of them can be identified with their near-infrared spectral indices.

  4. The HerMES SPIRE submillimeter local luminosity function

    OpenAIRE

    Vaccari, M.; Marchetti, L.; Franceschini, A.; Altieri, B.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Babbedge, T.; Blain, A.; Bock, J.; Boselli, A.; Buat, V.; Burgarella, D.; Castro-Rodriguez, N.

    2010-01-01

    Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel m...

  5. Bivariate luminosity function of E and SO galaxies

    International Nuclear Information System (INIS)

    A function which describes the joint distribution of luminosity and radius of galaxies - the bivariate luminosity function (BLF) is defined. A simple analytical formula for the shape of BLF is proposed and fitted to the data for E and SO galaxies from the sample of a previous author. (author)

  6. The Spitzer mid-infrared AGN survey. II-the demographics and cosmic evolution of the AGN population

    OpenAIRE

    Lacy, Mark; Ridgway, Susan E.; Sajina, Anna; Petric, Andreea O.; Gates, Elinor L.; Urrutia, Tanya; Storrie-Lombardi, Lisa J.

    2015-01-01

    We present luminosity functions derived from a spectroscopic survey of AGN selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of the obscured and unobscured AGN in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with...

  7. The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements. II. The Full Sample of Reverberation-Mapped AGNs

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Netzer, Hagai; Pogge, Richard W.; Vestergaard, Marianne

    2009-01-01

    We present high-resolution Hubble Space Telescope images of all 35 active galactic nuclei (AGNs) with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to...

  8. THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: THE QUASAR LUMINOSITY FUNCTION FROM DATA RELEASE NINE

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Nicholas P.; White, Martin; Bailey, Stephen [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); McGreer, Ian D. [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Palanque-Delabrouille, Nathalie; Yeche, Christophe [CEA, Centre de Saclay, IRFU, F-91191 Gif-sur-Yvette (France); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Shen, Yue; Swanson, Molly E. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Aubourg, Eric [APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite (France); Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); DeGraf, Colin; Di Matteo, Tiziana, E-mail: npross@lbl.gov [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); and others

    2013-08-10

    We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22,301 i {approx}< 21.8 quasars are selected over an area of 2236 deg{sup 2}, with confirmed spectroscopic redshifts between 2.2 < z < 3.5, filling in a key part of the luminosity-redshift plane for optical quasar studies. The completeness of the survey is derived through simulated quasar photometry, and this completeness estimate is checked using a sample of quasars selected by their photometric variability within the BOSS footprint. We investigate the level of systematics associated with our quasar sample using the simulations, in the process generating color-redshift relations and a new quasar K-correction. We probe the faint end of the QLF to M{sub i} (z = 2.2) Almost-Equal-To -24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log {Phi}* - M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of {approx}2.6 while {Phi}* declines by a factor of {approx}8. At z {approx}< 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of ''AGN downsizing'' is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities.

  9. Impact of the short-term luminosity evolution on luminosity function of star-forming galaxies

    CERN Document Server

    Parnovsky, S L

    2015-01-01

    An evolution of luminosity of galaxies in emission lines or wavelength ranges in which they are sensitive to the star formation process is caused by burning out of the most massive O-class stars during a few million years after a starburst. We study the impact of this effect on the luminosity function (LF) of a sample of star-forming galaxies. We introduce several types of LFs: an initial LF after a starburst, current, time-averaged and sample ones. We find the relations between them in general and specify them in the case of the luminosity evolution law proposed for the luminous compact galaxies. We obtain the sample LF for the cases the initial one is described by the pure Schechter function or the log-normal distribution and analyze the properties of these LFs. As a result we get two new types of LFs to fit the LF of a sample of star-forming galaxies.

  10. The UVX quasar optical luminosity function and its evolution

    CERN Document Server

    Goldschmidt, P; Goldschmidt, Pippa; Miller, Lance

    1997-01-01

    The recently-finished Edinburgh UVX quasar survey at B < 18 is used together with other complete samples to estimate the shape and evolution of the optical luminosity function in the redshift range 0.3 < z < 2.2. There is a significantly higher space density of quasars at high luminosity and low redshift than previously found in the PG sample of Schmidt \\& Green (1983), with the result that the shape of the luminosity function at low redshifts (z < 1) is seen to be consistent with a single power-law. At higher redshifts the slope of the power-law at high luminosities appears to steepen significantly. There does not appear to be any consistent break feature which could be used as a tracer of luminosity evolution in the population.

  11. THE RADIO LUMINOSITY FUNCTION AND GALAXY EVOLUTION IN THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 μJy per 4.''4 beam, we identify 249 radio sources with optical counterparts brighter than r = 22. For cluster galaxies, these correspond to L 1.4 = 1.7 x 1020 W Hz-1(for a 5σ source) and Mr = -13. Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are the dominant population only at radio luminosities between about 1021 and 1022 W Hz-1, an interesting result given star formation dominates field radio luminosity functions for all luminosities lower than about 1023 W Hz-1. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr ≤ -20.5) make the largest contribution to the radio luminosity function at both the high (∼>3x1022 W Hz-1) and low (∼21 W Hz-1) ends. Through a stacking analysis of these optically bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3 x 1019 W Hz-1. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (Mr ∼ -14) dwarf ellipticals hosting strong radio AGNs.

  12. A bimodal model for the galaxy luminosity function

    Science.gov (United States)

    Schaeffer, R.; Silk, J.

    1988-01-01

    The galaxy luminosity function in the Virgo cluster has been recently found to show a clear separation between bright galaxies and dwarf galaxies. Here, consideration is given to the effect on the luminosity function of galaxy binding energy which allows gas to be retained and star formation to proceed over about 1 Gyr in massive galaxies, but implies wind-driven mass loss and inefficient star formation in dwarf galaxies.

  13. The galaxy cluster mid-infrared luminosity function at 1.3 < z < 3.2

    Energy Technology Data Exchange (ETDEWEB)

    Wylezalek, Dominika; Vernet, Joël; De Breuck, Carlos [European Southern Observatory, Karl-Schwarzschildstr.2, D-85748 Garching bei München (Germany); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Brodwin, Mark [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Galametz, Audrey [INAF-Osservatorio di Roma, Via Frascati 33, I-00040, Monteporzio (Italy); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Jarvis, Matt [Astrophysics, Department of Physics, Keble Road, Oxford OX1 3RH (United Kingdom); Hatch, Nina [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom); Seymour, Nick [CASS, P.O. Box 76, Epping, NSW, 1710 (Australia); Stanford, Spencer A. [Physics Department, University of California, Davis, CA 95616 (United States)

    2014-05-01

    We present 4.5 μm luminosity functions for galaxies identified in 178 candidate galaxy clusters at 1.3 < z < 3.2. The clusters were identified as Spitzer/Infrared Array Camera (IRAC) color-selected overdensities in the Clusters Around Radio-Loud AGN project, which imaged 420 powerful radio-loud active galactic nuclei (RLAGNs) at z > 1.3. The luminosity functions are derived for different redshift and richness bins, and the IRAC imaging reaches depths of m* + 2, allowing us to measure the faint end slopes of the luminosity functions. We find that α = –1 describes the luminosity function very well in all redshift bins and does not evolve significantly. This provides evidence that the rate at which the low mass galaxy population grows through star formation gets quenched and is replenished by in-falling field galaxies does not have a major net effect on the shape of the luminosity function. Our measurements for m* are consistent with passive evolution models and high formation redshifts (z{sub f} ∼ 3). We find a slight trend toward fainter m* for the richest clusters, implying that the most massive clusters in our sample could contain older stellar populations, yet another example of cosmic downsizing. Modeling shows that a contribution of a star-forming population of up to 40% cannot be ruled out. This value, found from our targeted survey, is significantly lower than the values found for slightly lower redshift, z ∼ 1, clusters found in wide-field surveys. The results are consistent with cosmic downsizing, as the clusters studied here were all found in the vicinity of RLAGNs—which have proven to be preferentially located in massive dark matter halos in the richest environments at high redshift—and they may therefore be older and more evolved systems than the general protocluster population.

  14. The galaxy cluster mid-infrared luminosity function at 1.3 < z < 3.2

    International Nuclear Information System (INIS)

    We present 4.5 μm luminosity functions for galaxies identified in 178 candidate galaxy clusters at 1.3 < z < 3.2. The clusters were identified as Spitzer/Infrared Array Camera (IRAC) color-selected overdensities in the Clusters Around Radio-Loud AGN project, which imaged 420 powerful radio-loud active galactic nuclei (RLAGNs) at z > 1.3. The luminosity functions are derived for different redshift and richness bins, and the IRAC imaging reaches depths of m* + 2, allowing us to measure the faint end slopes of the luminosity functions. We find that α = –1 describes the luminosity function very well in all redshift bins and does not evolve significantly. This provides evidence that the rate at which the low mass galaxy population grows through star formation gets quenched and is replenished by in-falling field galaxies does not have a major net effect on the shape of the luminosity function. Our measurements for m* are consistent with passive evolution models and high formation redshifts (zf ∼ 3). We find a slight trend toward fainter m* for the richest clusters, implying that the most massive clusters in our sample could contain older stellar populations, yet another example of cosmic downsizing. Modeling shows that a contribution of a star-forming population of up to 40% cannot be ruled out. This value, found from our targeted survey, is significantly lower than the values found for slightly lower redshift, z ∼ 1, clusters found in wide-field surveys. The results are consistent with cosmic downsizing, as the clusters studied here were all found in the vicinity of RLAGNs—which have proven to be preferentially located in massive dark matter halos in the richest environments at high redshift—and they may therefore be older and more evolved systems than the general protocluster population.

  15. The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Ajello, M.; Shaw, M.S.; Romani, R.W.; Dermer, C.D.; Costamante, L.; King, O.G.; Max-Moerbeck, W.; Readhead, A.; Reimer, A.; Richards, J.L.; Stevenson, M.

    2012-04-16

    Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent only {approx}0.1% of the parent population.

  16. Evolution of the cluster X-ray luminosity function

    DEFF Research Database (Denmark)

    Mullis, C.R.; Vikhlinin, A.; Henry, J.P.; Forman, W.; Gioia, I.M.; Hornstrup, Allan; Jones, C.; McNamara, B.R.; Quintana, H.

    2004-01-01

    than a few times 10(44) h(50)(-2) ergs s(-1) (0.5 - 2.0 keV). However, for 0.6 luminosities above 10(44) h(50)(-2) ergs s(-1), the observed volume densities are significantly lower than those of the present-day population. We quantify this cluster deficit using integrated number counts...... and a maximum likelihood analysis of the observed luminosity-redshift distribution fit with a model luminosity function. The negative evolution signal is more than 3 sigma regardless of the adopted local luminosity function or cosmological framework. Our results and those from several other surveys...... independently confirm the presence of evolution. Whereas the bulk of the cluster population does not evolve, the most luminous and presumably most massive structures evolve appreciably between z = 0.8 and the present. Interpreted in the context of hierarchical structure formation, we are probing sufficiently...

  17. The 1Luminosity Function of Type I Quasars

    CERN Document Server

    Brown, M J I; Dey, A; Jannuzi, B T; Cool, R; Le Floc'h, E; Kochanek, C S; Armus, L; Bian, C; Higdon, J; Higdon, S; Papovich, C; Rieke, G; Rieke, M; Smith, J D; Soifer, B T; Weedman, D; Brown, Michael J. I.; Brand, Kate; Dey, Arjun; Jannuzi, Buell T.; Cool, Richard; Floc'h, Emeric Le; Kochanek, Christopher S.; Armus, Lee; Bian, Chao; Higdon, Jim; Higdon, Sarah; Papovich, Casey; Rieke, George; Rieke, Marcia; Weedman, Dan

    2006-01-01

    We determine the rest-frame 8 micron luminosity function of type I quasars over the redshift range 1AGN and Galaxy Evolution Survey (AGES) has measured redshifts for 270 of the R<21.7 sources and we estimate that the contamination of the remaining 22 sources by stars and galaxies is low. We are able to select quasars missed by ultra-violet excess quasar surveys, including reddened type I quasars and 2.2luminosity function is comparable to that of quasars selected from optical surveys. The 8 micron luminosity function of type I quasars is well approximated by a power-law with i...

  18. The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster

    Science.gov (United States)

    Miller, Neal A.; Hornschemeier, Ann E.; Mabasher, Bahram; Brudgesm Terrry J.; Hudson, Michael J.; Marzke, Ronald O.; Smith, Russell J.

    2008-01-01

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 (mu)Jy per 4.4" beam, we identify 249 radio sources with optical counterparts brighter than r = 22 (equivalent to M(sub r) = -13 for cluster member galaxies). Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are restricted to radio luminosities between about 10(exp 21) and 10(exp 22) W/Hz, an interesting result given that star formation dominates field radio luminosity functions below about 10(exp 23) W/Hz. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr less than or equals -20.5) make the largest contribution to the radio luminosity function at both the high (> approx. 3x10(exp 22) W/Hz) and low (< approx. 10(exp 21) W/Hz) ends. Through a stacking analysis of these optically-bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3x10(exp 19) W/Hz. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (M(sub r) approx. equals -14) dwarf ellipticals hosting strong radio AGN.

  19. The luminosity function of Swift long gamma-ray bursts

    CERN Document Server

    Cao, Xiao-Feng; Cheng, K S; Zheng, Xiao-Ping

    2011-01-01

    The formation rate of long gamma-ray bursts (GRBs) could follow the cosmic star formation rate (SFR) incorporating with cosmic metallicity evolution. Therefore, the luminosity function (LF) of GRBs can in principle be explored by modeling the redshift-luminosity distributions of {\\it Swift} observed GRBs. For an assumed LF form as $\\Phi_z(L)\\propto e^{-L_p/L}\\left({L/L_p}\\right)^{-\

  20. The intrinsic quasar luminosity function: Accounting for accretion disk anisotropy

    International Nuclear Information System (INIS)

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic—in part due to its disk-like structure—but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic luminosity function by as much as a factor of ∼2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

  1. The galaxy luminosity function and the Local Hole

    Science.gov (United States)

    Whitbourn, J. R.; Shanks, T.

    2016-06-01

    In a previous study Whitbourn & Shanks have reported evidence for a local void underdense by ≈15 per cent extending to 150-300 h-1 Mpc around our position in the Southern Galactic Cap (SGC). Assuming a local luminosity function they modelled K- and r-limited number counts and redshift distributions in the 6dFGS/2MASS and SDSS redshift surveys and derived normalized n(z) ratios relative to the standard homogeneous cosmological model. Here we test further these results using maximum likelihood techniques that solve for the galaxy density distributions and the galaxy luminosity function simultaneously. We confirm the results from the previous analysis in terms of the number density distributions, indicating that our detection of the `Local Hole' in the SGC is robust to the assumption of either our previous, or newly estimated, luminosity functions. However, there are discrepancies with previously published K- and r-band luminosity functions. In particular the r-band luminosity function has a steeper faint end slope than the r0.1 results of Blanton et al. but is consistent with the r0.1 results of Montero-Dorta & Prada and Loveday et al.

  2. The galaxy luminosity function and the Local Hole

    CERN Document Server

    Whitbourn, J R

    2016-01-01

    Whitbourn & Shanks (2014) have reported evidence for a local void underdense by ~15% extending to 150-300h-1Mpc around our position in the Southern Galactic Cap (SGC). Assuming a local luminosity function they modelled K- and r-limited number counts and redshift distributions in the 6dFGS/2MASS and SDSS redshift surveys and derived normalised n(z) ratios relative to the standard homogeneous cosmological model. Here we test further these results using maximum likelihood techniques that solve for the galaxy density distributions and the galaxy luminosity function simultaneously. We confirm the results from the previous analysis in terms of the number density distributions, indicating that our detection of the 'Local Hole' in the SGC is robust to the assumption of either our previous, or newly estimated, luminosity functions. However, there are discrepancies with previously published K and r band luminosity functions. In particular the r-band luminosity function has a steeper faint end slope than the r0.1 re...

  3. The Ultraviolet Luminosity Function of the Earliest Galaxies

    CERN Document Server

    O'Shea, Brian W; Xu, Hao; Norman, Michael L

    2015-01-01

    In this paper, we present the first results from the Renaissance Simulations, a suite of extremely high-resolution and physics-rich AMR calculations of high redshift galaxy formation performed on the Blue Waters supercomputer. These simulations contain hundreds of well-resolved galaxies at $z \\sim 25-8$, and make several novel, testable predictions. Most critically, we show that the ultraviolet luminosity function of our simulated galaxies is consistent with observations of high-z galaxy populations at the bright end of the luminosity function (M$_{1600} \\leq -17$), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations. This flattening of the luminosity function is due to two factors: (i) the strong dependence of the stellar fraction on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower stellar fractions and thus lower luminosities at a given halo virial mass; and (ii)...

  4. Evidence for steep luminosity functions in clusters of galaxies

    CERN Document Server

    De Propris, R; Harris, W E; McClure, R D; De Propris, R; Pritchet, C J; Harris, W E; McClure, R D

    1995-01-01

    Luminosity Functions have been obtained for very faint dwarf galaxies in the cores of four rich clusters of galaxies (Abell 2052, 2107, 2199 and 2666). It is found that the luminosity function of dwarf galaxies rises very steeply in these clusters, with a power-law slope of \\alpha -2.2 (down to absolute limiting magnitudes M_I = -13 and M_B = -11 for H_0 = 75 km/s/Mpc). A steepening of the luminosity function at faint magnitudes may in fact be a common feature of both cluster and field populations. Such a result may explain the observed excess counts of faint, intermediate redshift galaxies in the Universe, without resorting to more exotic phenomena. An alternate explanation is that star formation in dwarf galaxies is less affected by gas loss in the richest clusters, because of the dense, hot intracluster medium found in such environments.

  5. Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-thick Populations

    Science.gov (United States)

    Ueda, Yoshihiro; Akiyama, Masayuki; Hasinger, Günther; Miyaji, Takamitsu; Watson, Michael G.

    2014-05-01

    We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ~ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ≈0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

  6. Toward the standard population synthesis model of the X-ray background: Evolution of X-ray luminosity and absorption functions of active galactic nuclei including Compton-thick populations

    International Nuclear Information System (INIS)

    We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ∼ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ≈0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

  7. The HerMES SPIRE submillimeter local luminosity function

    CERN Document Server

    Vaccari, M; Franceschini, A; Altieri, B; Amblard, A; Arumugam, V; Auld, R; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Dye, S; Eales, S; Elbaz, D; Farrah, D; Fox, M; Gear, W; Glenn, J; Solares, E A Gonzalez; Griffin, M; Halpern, M; Hatziminaoglou, E; Huang, J; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rawlings, J I; Raymond, G; Rigopoulou, D; Rizzo, D; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Valiante, E; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

    2010-01-01

    Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel measurement of the submillimeter 0luminosity function and infrared bolometric (8-1000 $\\mu$m) local luminosity density based on SPIRE data from the HerMES Herschel Key Program over 14.7 deg^2. Flux measurements in the three SPIRE channels at 250, 350 and 500 \\mum are combined with Spitzer photometry and archival data. We fit the observed optical-to-submillimeter spectral energy distribution of SPIRE sources and use the 1/V_{max} estimator to provide the first constraints on the monochromatic 250, 350 and ...

  8. Luminosity Function of Faint Globular Clusters in M87

    CERN Document Server

    Waters, C Z; Lauer, T R; Baltz, E A; Silk, J; Waters, Christopher Z.; Zepf, Stephen E.; Lauer, Tod R.; Baltz, Edward A.; Silk, Joseph

    2006-01-01

    We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit \\textit{Hubble Space Telescope (HST)} WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky Way. We also find with high statistical significance that the M87 luminosity function is broader than that of the Milky Way. We discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems. Our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence. In addition, the rat...

  9. Models of the quasar population. I. A new luminosity function

    International Nuclear Information System (INIS)

    A new functional form for the quasar luminosity function is tested using recent observational results for both bright and faint quasar count and redshift distributions. The form is of a fairly general type based on three free parameters and allows for quasars to undergo a combination of luminosity evolution and luminosity-dependent density evolution; an advantage to this approach is that it does not constrain quasars to follow a single type of evolution. Models of pure luminosity evolution or luminosity-dependent density evolution can be constructed, but the apparent magnitude distribution of observed quasars is best fitted by a combination model. The combination model also gives the correct redshift distribution for quasars with redshifts less than three and predicts that quasars brighter than B = 22 provide a 2-10 keV X-ray flux that is equal to 32 percent of the observed X-ray background. However, the model is flawed in that it predicts more high-redshift quasars than are observed. 45 references

  10. The Spitzer mid-infrared AGN survey. II-the demographics and cosmic evolution of the AGN population

    CERN Document Server

    Lacy, Mark; Sajina, Anna; Petric, Andreea O; Gates, Elinor L; Urrutia, Tanya; Storrie-Lombardi, Lisa J

    2015-01-01

    We present luminosity functions derived from a spectroscopic survey of AGN selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of the obscured and unobscured AGN in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts ($z>1.6$), we find significantly more AGN at a given bolometric luminosity than found by either optical quasar surveys or hard X-ray surveys. The fraction of obscured AGN decreases rapidly with increasing AGN luminosity, but, at least at high redshifts, appears to remain at $\\approx 50$\\% even at bolometric luminosities $\\sim 10^{14}L_{\\odot}$. The data support a picture in which the obscured and unobscured populations evolve differently, with some evidence that high luminosity obscured quasar...

  11. The faint end of the galaxy luminosity function

    Science.gov (United States)

    Treyer, Marie A.; Silk, Joseph

    1994-01-01

    The evolution of the B- and K-band luminosity functions of galaxies is inferred in a relatively model-independent way from deep spectroscopic and photometric surveys. We confirm earlier evidence by Eales for an increase in the amplitude of the B-band galaxy luminosity function at modest redshift (z less than or approx. 0.2). We find in addition that the slope of the faint end of the luminosity function must systematically steepen and progress toward more luminous galaxies with increasing lookback time, assuming that the galaxy redshift distribution may be smoothly extrapolated 2 mag fainter than observed, as suggested by recent gravitational lensing studies. This evolution is shown to be color-dependent, and we predict the near-infrared color distribution of faint galaxies. The luminosity function of blue (B - K less than or approx. 4) galaxies in the range 0.2 less than or approx. z less than or approx. 1 can be represented by a Schechter function with characteristic light density phi(sup *) L(sup *) comparable to that of present-day late-type galaxies, but with a steeper faint end slope alpha approx. 1.4.

  12. The luminosity function and formation rate history of GRBs

    International Nuclear Information System (INIS)

    The isotropic luminosity function (LF) and formation rate history (FRH) of long GRBs is by the first time constrained by using jointly both the observed GRB peak-flux and redshift distributions. Our results support an evolving LF and a FRH that keeps increasing after z = 2. We discuss some interesting implications related to these results

  13. Erratum - The many lives of AGN: cooling flows, black holes and the luminosities and colours of galaxies

    CERN Document Server

    Croton, D J; White, S D M; De Lucia, G; Frenk, C S; Gao, L; Jenkins, A; Kauffmann, G; Navarro, J F; Yoshida, N; Croton, Darren J.; Springel, Volker; White, Simon D. M.

    2006-01-01

    In Figure 6 we inadvertently labeled the proxy circular velocity as the virial velocity of the dark matter halo instead of what is actually plotted, the maximum circular velocity of the dark matter halo. The maximum halo circular velocity is a much better estimate of the disk V_c than is V_vir. This confusion influenced the discussion of the Tully-Fisher relation in our paper. In fact, Figure 6 demonstrates that it is possible to simultaneously reproduce both the local Tully-Fisher relation and luminosity function using semi-analytic techniques applied to the standard LCDM cosmology, thus contradicting previous studies of this issue and our own discussion in Section 3.6.

  14. Luminosity function of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

    CERN Document Server

    Berton, Marco; Foschini, Luigi; Peterson, Bradley M; Mathur, Smita; Terreran, Giacomo; Ciroi, Stefano; Congiu, Enrico; Cracco, Valentina; Frezzato, Michele; La Mura, Giovanni; Rafanelli, Piero

    2016-01-01

    Narrow-line Seyfert 1 galaxies are an interesting subclass of active galactic nuclei (AGN), which tipically does not exhibit any strong radio emission. Seven percent of them, though, are radio-loud and often show a flat radio-spectrum (F-NLS1s). This, along to the detection of $\\gamma$-ray emission coming from them, is usually interpreted as a sign of a relativistic beamed jet harbored in these objects. An important aspect of these AGN that must be understood is the nature of their parent population, in other words how do they appear when observed under different angles. In this paper we investigated whether compact steep-spectrum sources with an high excitation spectrum (CSS/HERGs) are good parent candidates. To do this, we analyzed the only two statistically complete samples of CSS/HERGs and F-NLS1s available in the literature. We derived the black hole mass and Eddington ratio distributions, and we built for the first time the radio luminosity function of F-NLS1s. Finally, we applied a relativistic beaming...

  15. A new cosmological distance measure using AGN X-ray variability

    OpenAIRE

    La Franca, Fabio; Bianchi, Stefano; Ponti, Gabriele; Branchini, Enzo; Matt, Giorgio

    2014-01-01

    We report the discovery of a luminosity distance estimator using Active Galactic Nuclei (AGN). We combine the correlation between the X-ray variability amplitude and the Black Hole (BH) mass with the single epoch spectra BH mass estimates which depend on the AGN luminosity and the line width emitted by the broad line region. We demonstrate that significant correlations do exist which allows one to predict the AGN (optical or X-ray) luminosity as a function of the AGN X-ray variability and eit...

  16. The Luminosity Function of PNe with different morphology

    OpenAIRE

    Magrini, L.; R. L. M. Corradi; Leisy, P.; Scatarzi, A.; L. Morbidelli; Perinotto, M.

    2003-01-01

    We have analyzed the behaviour of various parameters of PNe in the Magellanic Clouds (MCs) and the Galaxy as a function of their morphology. The luminosity function of different morphological types has been built, finding that elliptical and round PNe dominate the bright cutoff both in the MCs and in the Galaxy. The dependence of the [OIII] absolute magnitude on chemical abundances has been investigated.

  17. The OPTX Project II: Hard X-ray Luminosity Functions of Active Galactic Nuclei for z<5

    OpenAIRE

    Yencho, B.; Barger, A. J.; Trouille, L.; Winter, L. M.

    2009-01-01

    We use the largest, most uniform, and most spectroscopically complete to faint X-ray flux limits Chandra sample to date to construct hard 2-8 keV rest-frame X-ray luminosity functions (HXLFs) of spectroscopically identified active galactic nuclei (AGNs) to z~5. In addition, we use a new 2-8 keV local sample selected by the very hard (14-195 keV) SWIFT 9-month Burst Alert Telescope (BAT) survey to construct the local 2-8 keV HXLF. We do maximum likelihood fits of the combined distant plus loca...

  18. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Jiang Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ross, Nicholas P.; White, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schneider, Donald P.; Brandt, W. Niel [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); DeGraf, Colin [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Ge Jian [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Streblyanska, Alina, E-mail: imcgreer@as.arizona.edu [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  19. Low-Luminosity Seyfert Nuclei

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    1996-01-01

    We describe a new sample of Seyfert nuclei discovered during the course of an optical spectroscopic survey of nearby galaxies. The majority of the objects, many recognized for the first time, have luminosities much lower than those of classical Seyferts and populate the faint end of the AGN luminosity function. A significant fraction of the nuclei emit broad H-alpha emission qualitatively similar to the broad lines seen in classical Seyfert 1 nuclei and QSOs.

  20. The VLA Survey of Chandra Deep Field South. V. Evolution and Luminosity Functions of Sub-millijansky Radio Sources and the Issue of Radio Emission in Radio-quiet Active Galactic Nuclei

    Science.gov (United States)

    Padovani, P.; Miller, N.; Kellermann, K. I.; Mainieri, V.; Rosati, P.; Tozzi, P.

    2011-10-01

    We present the evolutionary properties and luminosity functions of the radio sources belonging to the Chandra Deep Field South Very Large Array survey, which reaches a flux density limit at 1.4 GHz of 43 μJy at the field center and redshift ~5 and which includes the first radio-selected complete sample of radio-quiet active galactic nuclei (AGNs). We use a new, comprehensive classification scheme based on radio, far- and near-IR, optical, and X-ray data to disentangle star-forming galaxies (SFGs) from AGNs and radio-quiet from radio-loud AGNs. We confirm our previous result that SFGs become dominant only below 0.1 mJy. The sub-millijansky radio sky turns out to be a complex mix of SFGs and radio-quiet AGNs evolving at a similar, strong rate; non-evolving low-luminosity radio galaxies; and declining radio powerful (P >~ 3 × 1024 W Hz-1) AGNs. Our results suggest that radio emission from radio-quiet AGNs is closely related to star formation. The detection of compact, high brightness temperature cores in several nearby radio-quiet AGNs can be explained by the coexistence of two components, one non-evolving and AGN related and one evolving and star formation related. Radio-quiet AGNs are an important class of sub-millijansky sources, accounting for ~30% of the sample and ~60% of all AGNs, and outnumbering radio-loud AGNs at bypassing the problems of obscuration that plague the optical and soft X-ray bands.

  1. Cosmological Tests with the FSRQ Gamma-ray Luminosity Function

    CERN Document Server

    Zeng, Houdun; Zhang, Li

    2016-01-01

    The extensive catalog of $\\gamma$-ray selected flat-spectrum radio quasars (FSRQs) produced by \\emph{Fermi} during a four-year survey has generated considerable interest in determining their $\\gamma$-ray luminosity function (GLF) and its evolution with cosmic time. In this paper, we introduce the novel idea of using this extensive database to test the differential volume expansion rate predicted by two specific models, the concordance $\\Lambda$CDM and $R_{\\rm h}=ct$ cosmologies. For this purpose, we use two well-studied formulations of the GLF, one based on pure luminosity evolution (PLE) and the other on a luminosity-dependent density evolution (LDDE). Using a Kolmogorov-Smirnov test on one-parameter cumulative distributions (in luminosity, redshift, photon index and source count), we confirm the results of earlier works showing that these data somewhat favour LDDE over PLE; we show that this is the case for both $\\Lambda$CDM and $R_{\\rm h}=ct$. Regardless of which GLF one chooses, however, we also show that...

  2. X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku

    OpenAIRE

    Fioretti, V.; L. Angelini; Mushotzky, R. F.; Koss, M; Malaguti, G.

    2013-01-01

    The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10^-11 erg cm^-2 s^-1 and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 < Log L(BAT) < 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. ...

  3. The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

    International Nuclear Information System (INIS)

    Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of ∼2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a ∼5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN-LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN-LogS of AGN selected above 10 keV is now established to a ∼10% precision. We derive the luminosity function of Compton-thick AGN and measure a space density of 7.9-2.9+4.1 x 10-5 Mpc-3 for objects with a de-absorbed luminosity larger than 2 x 1042 erg s-1. As the BAT AGN are all mostly local, they allow us to investigate the spatial distribution of AGN in the nearby Universe regardless of absorption. We find concentrations of AGN that coincide spatially with the largest congregations of matter in the local ((le) 85 Mpc) Universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

  4. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    International Nuclear Information System (INIS)

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M1450 2, then extend to lower luminosities (M1450 2 of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 1450*∼-27). The bright-end slope is steep (β ∼1450 < –26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate ∼30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  5. Evolution of the cluster X-ray luminosity function

    DEFF Research Database (Denmark)

    Mullis, C.R.; Vikhlinin, A.; Henry, J.P.;

    2004-01-01

    We report measurements of the cluster X-ray luminosity function out to z = 0.8 based on the final sample of 201 galaxy systems from the 160 Square Degree ROSAT Cluster Survey. There is little evidence for any measurable change in cluster abundance out to z similar to 0.6 at luminosities of less...... than a few times 10(44) h(50)(-2) ergs s(-1) (0.5 - 2.0 keV). However, for 0.6 z ... independently confirm the presence of evolution. Whereas the bulk of the cluster population does not evolve, the most luminous and presumably most massive structures evolve appreciably between z = 0.8 and the present. Interpreted in the context of hierarchical structure formation, we are probing sufficiently...

  6. AGN evolution from a galaxy evolution viewpoint

    CERN Document Server

    Caplar, Neven; Trakhtenbrot, Benny

    2014-01-01

    We explore the connections between the evolving galaxy and AGN populations. We present a simple phenomenological model that links the evolving galaxy mass function and the evolving quasar luminosity function, motivated by similarities between the two, which makes specific and testable predictions for the distribution of host galaxy masses for AGN of different luminosities. We show that the phi$^{*}$ normalisations of the galaxy mass function and the AGN luminosity function closely track each other over a wide range of redshifts, implying a constant "duty cycle" of AGN activity. The strong redshift evolution in the AGN break luminosity $L^*$ is produced by either an evolution in the distribution of Eddington rations, or in the $m_{bh}/m_{*}$ mass ratio, or both. An evolving $m_{bh}/m_{*}$ ratio, such that it is ten times higher at $z \\sim 2$ (i.e. roughly following $(1+z)^{2}$), reproduces the observed distribution of SDSS quasars in the ($m_{bh},L$) plane and accounts for the apparent "sub-Eddington boundary"...

  7. Applying the luminosity function statistics in the fireshell model

    Science.gov (United States)

    Rangel Lemos, L. J.; Bianco, C. L.; Ruffini, R.

    2015-12-01

    The luminosity function (LF) statistics applied to the data of BATSE, GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We applied the tool of the LF statistics to three GRB classes predicted by the Fireshell model. We produced, by LF statistics, predicted distributions of: peak ux N(Fph pk), redshift N(z) and peak luminosity N(Lpk) for the three GRB classes predicted by Fireshell model; we also used three GRB rates. We looked for differences among the distributions, and in fact we found. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with 217 GRBs with known redshifts. Our goal is transform the GRBs in a standard candle, where a alternative is find a correlation between the isotropic luminosity and the Band peak spectral energy (Liso - Epk).

  8. The NuSTAR Extragalactic Survey: First Direct Measurements of the Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At z > 0.1

    DEFF Research Database (Denmark)

    Aird, J.; Alexander, D. M.; Ballantyne, D. R.;

    2015-01-01

    We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1

  9. Weighing neutrinos using high redshift galaxy luminosity functions

    International Nuclear Information System (INIS)

    We have proposed a novel way to constrain the neutrino mass using UV luminosity function (LF) of high-z Lyman break galaxies. Combining the constraints from the Wilkinson Microwave Anisotropy Probe 7 year (WMAP-7) data with the LF data at z ∼ 4, we have got a limit on the sum of the masses of 3 degenerate neutrinos at the 95 % CL. The additional constraint of using the prior on Hubble constant strengthens this limit to at 95 % CL. As different astronomical measurements may suffer from different set of biases, the method presented here provides a complementary probe of sum of neutrino masses

  10. Relativistic Cosmology Number Densities and the Luminosity Function

    CERN Document Server

    Iribarrem, Alvaro S; Ribeiro, Marcelo B; Stoeger, William R

    2012-01-01

    This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaitre-Robertson-Walker spacetime with non-vanishing cosmological constant and the galaxy luminosity function (LF) data. It extends the redshift range of previous results presented in Albani et al. (2007, arXiv:astro-ph/0611032) where the galaxy distribution was studied out to z=1. Observational inhomogeneities were detected at this range. This research also searches for LF evolution in the context of the framework advanced by Ribeiro and Stoeger (2003, arXiv:astro-ph/0304094), further developing the theory linking relativistic cosmology theory and LF data. Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy luminosity functions obtained from an I-band selected dataset of the FORS Deep Field galaxy survey in the redshift range 0.5

  11. Luminosity Function of the Cluster of Galaxies Abell 566

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We investigate the Luminosity Function (LF) of the cluster of galaxies Abell 566. The photometric data of 15 intermediate-bands are obtained from the Beijing- Arizona-Taiwan-Connecticut (BATC) photometric sky survey. For each of the 15 wavebands, the LF of cluster galaxies is well modelled by the Schechter function, with characteristic luminosities from -18.0 to -21.9 magnitude, from the a- to the p-band. Morphological dependence of the LF is investigated by separating the cluster members into 'red' and 'blue' subsamples. It is clear that late type galaxies have a steeper shape of LF than the early type galaxies. We also divided the sample galaxies by their local environment. It was found that galaxies in the sparser region have steeper shape of LF than galaxies in the denser region. Combining the results of morphological and environmental dependence of LFs, we show that Abell 566 is a well relaxed cluster with positive evidence of galaxy interaction and merger, and excess number of bright early type galaxies located in its denser region.

  12. Physics as a function of energy and luminosity

    International Nuclear Information System (INIS)

    In this paper, a new physics in the range of mass up to TeV region is discussed. Most of the discussion concern hadron-hadron (hh) colliders, and also electron-positron colliders are discussed. The cross-sections for new particle production in hh colliders have the general Drell-Yan form, in which the differential luminosity for the collision of partons is included. The formulas with the parton distribution scaled up from present energy using the Altarelli-Parisi equations may be approximately correct within a factor of 2 for the production of particles. Some typical parton-parton luminosity functions for proton-proton and proton-antiproton collisions are presented. From the consideration of luminosity, it can be said that the pp colliders are to be preferred. The case studies of some of the possible new physics discussed by Zakharov, mainly on Higgs bosons and supersymmetric particles, but also a few remarks about technicolor are presented. It seems possible to detect technicolor at a large hh collider. The physics reaches of different possible hh colliders are summarized in tables. In the tables, the observable production of Higgses up to 1 TeV in mass, the observable masses for gluinos (squarks) and the technicolor observability are shown. The cleanliness of electron-positron colliders compared to hadron-hadron colliders is pled, a guess is given as to the appropriate conversion factors between the energy in the electron-positron and hh collisions, the complementarity of electron-positron and hh colliders is urged, and it is argued that a rational mix of world accelerators would include both. (Kato, T.)

  13. The Mid-Infrared Color-Luminosity Relation and the Local 12 micron Luminosity Function

    OpenAIRE

    Fang, Fan; Shupe, David L.; Xu, Cong; Hacking, Perry B.

    1998-01-01

    We have established a model to systematically estimate the contribution of the mid-infrared emission features between 3 and 11.6 micron to the IRAS in-band fluxes, using the results of ISO PHT-S observation of 16 galaxies by Lu et al. (1997). The model is used to estimate more properly the k-corrections for calculating the restframe 12 and 25 micron fluxes and luminosities of IRAS galaxies. We have studied the 12-25 micron color-luminosity relation for a sample of galaxies selected at 25 micr...

  14. Luminosity function of the brightest galaxies in the IRAS survey

    International Nuclear Information System (INIS)

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume

  15. Differential Density Statistics of Galaxy Distribution and the Luminosity Function

    CERN Document Server

    Albani, V V L; Ribeiro, M B; Stöger, W R; Albani, Vinicius V. L.; Iribarrem, Alvaro S.; Ribeiro, Marcelo B.; Stoeger, William R.

    2006-01-01

    This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number densities statistics of the galaxy distribution as discussed in Ribeiro (2005), namely the differential density $\\gamma$ and the integral differential density $\\gamma^\\ast$. By applying the theory advanced by Ribeiro and Stoeger (2003), which connects the relativistic cosmology number counts with the astronomically derived LF, the differential number counts $dN/dz$ are extracted from the LF and used to calculate both $\\gamma$ and $\\gamma^\\ast$ with various cosmological distance definitions, namely the area distance, luminosity distance, galaxy area distance and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey and $\\gamma$ and $\\gamma^\\ast$ are calculated for two cosmological models: Einstein-de Sitter and an $\\Omega_{m_0}=0.3$, $\\Omega_{\\Lambda_0}=0.7$ standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in...

  16. On the universal X-ray luminosity function of binary X-ray sources in galaxies

    OpenAIRE

    Postnov, K. A.

    2002-01-01

    The empirically determined universal power-law shape of X-ray luminosity function of high mass X-ray binaries in galaxies is explained by fundamental mass-luminosity and mass-radius relations for massive stars.

  17. A survey of Low Luminosity Compact sources and its implication for evolution of radio-loud AGNs. II. Optical analysis

    CERN Document Server

    Kunert-Bajraszewska, M

    2010-01-01

    This is the second in a series of papers concerning a new sample of low luminosity compact (LLC) objects. Here we discuss the optical properties of the sample based on Sloan Digital Sky Survey (SDSS) images and spectra. We have generated different diagnostic diagrams and classified the sources as high and low excitation galaxies (HEG and LEG, respectively). We have studied the jet-host interactions, relation between radio and optical line emission and evolution of the radio source within a larger sample that included also the published samples of compact steep spectrum (CSS), gigahertz peaked spectrum (GPS) sources and FRII and FRI objects. The optical and radio properties of the LLC sample are in general consistent with brighter CSS and large-scale radio sources, although the LLC objects have lower values of [OIII] luminosity than the more powerful CSS sources (L_1.4GHz>10^25 W/Hz). However, when LLC are added to the other samples, HEG and LEG seem to follow independent, parallel evolutionary tracks. Regardi...

  18. The infrared luminosity function for low-mass stars

    International Nuclear Information System (INIS)

    The first infrared observational luminosity functions (LFs) for M dwarfs towards the South Galactic Pole (SGP) and the Hyades cluster are presented. We also give a definitive compilation of new and published VRIJHK data for 200 parallax stars, for deriving photometric parallaxes in such studies. Two-colour near-infrared/infrared diagrams of these data are used to demonstrate metallicity and gravity effects, and show that I-J is the purest temperature colour index. An MJ:I-J relation is given using high-quality trigonometric parallaxes from the new Yale catalogue. We describe the corrections to the LFs that are necessary to allow for magnitude errors (Malmquist effects), which have been incorrectly applied in recent determinations. (author)

  19. The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming Regions

    CERN Document Server

    Cook, David O; Lee, Janice C; Thilker, David; Calzetti, Daniela; Kennicutt, Robert C

    2016-01-01

    We present the first study of GALEX far ultra-violet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65,000 star-forming regions (i.e., FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (alpha) and several global galaxy properties. A final sample of 82 galaxies with reliable luminosity functions are used to define these relationships and represent the largest sample of galaxies with the largest range of galaxy properties used to study the connection between luminosity function properties and galaxy environment. We find that alpha correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities (Sigma_SFR) tend to have flatter luminosity function slopes. In addition, we find that neither stochastic sampling of the luminosity f...

  20. The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

    CERN Document Server

    Ajello, M; Greiner, J; Madejski, G M; Gehrels, N; Burlon, D

    2012-01-01

    Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15--55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of \\sim2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a ~5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN--LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN--LogS of AGN selected above 10 keV is now established to a ~10% precision. We derive the luminosity function of Compton-thick ...

  1. The Luminosity Function of Low-Redshift Abell Galaxy Clusters

    CERN Document Server

    Barkhouse, Wayne A; López-Cruz, Omar

    2007-01-01

    We present the results from a survey of 57 low-redshift Abell galaxy clusters to study the radial dependence of the luminosity function (LF). The dynamical radius of each cluster, r200, was estimated from the photometric measurement of cluster richness, Bgc. The shape of the LFs are found to correlate with radius such that the faint-end slope, alpha, is generally steeper on the cluster outskirts. The sum of two Schechter functions provides a more adequate fit to the composite LFs than a single Schechter function. LFs based on the selection of red and blue galaxies are bimodal in appearance. The red LFs are generally flat for -22 -18. The blue LFs contain a larger contribution from faint galaxies than the red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc > -21, with a weaker dependence on radius than the red LFs. The dispersion of M* was determined to be 0.31 mag, which is comparable to the median measurement uncertainty of 0.38 mag. This suggests that the bright-end of the LF is...

  2. Extra-galactic high-energy transients: event rate densities and luminosity functions

    CERN Document Server

    Sun, Hui; Li, Zhuo

    2015-01-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with an associated relativistic jet. In this paper, we apply a unified method to systematically study the redshift-dependent event rate densities and the global luminosity functions (ignoring redshift evolution) of these transients. We introduce some empirical formulae for the redshift-dependent event rate densities for different types of transients, and derive the local specific event rate density, which also represents its global luminosity function. Long GRBs have a large enough sample to reveal features in the global luminosity function, which is best characterized as a triple power law. All the other transients are consistent with having a single power law luminosity function. The total event rate density depends on the minimum luminosity, and...

  3. The galaxy luminosity function in groups and clusters: the faint-end upturn and the connection to the field luminosity function

    Science.gov (United States)

    Lan, Ting-Wen; Ménard, Brice; Mo, Houjun

    2016-07-01

    We characterize the luminosity functions of galaxies residing in z ˜ 0 groups and clusters over the broadest ranges of luminosity and mass reachable by the Sloan Digital Sky Survey. Our measurements cover four orders of magnitude in luminosity, down to about Mr = -12 mag or L = 107 L⊙, and three orders of magnitude in halo mass, from 1012 to 1015 M⊙. We find a characteristic scale, Mr ˜ -18 mag or L ˜ 109 L⊙, below which the slope of the luminosity function becomes systematically steeper. This trend is present for all halo masses and originates mostly from red satellites. This ubiquitous faint-end upturn suggests that it is formation, rather than halo-specific environmental effect, that plays a major role in regulating the stellar masses of faint satellites. We show that the satellite luminosity functions can be described in a simple manner by a double Schechter function with amplitudes scaling with halo mass over the entire range of observables. Combining these conditional luminosity functions with the dark matter halo mass function, we accurately recover the entire field luminosity function over 10 visual magnitudes and reveal that satellite galaxies dominate the field luminosity function at magnitudes fainter than -17. We find that the luminosity functions of blue and red satellite galaxies show distinct shapes and we present estimates of the stellar mass fraction as a function of halo mass and galaxy type. Finally, using a simple model, we demonstrate that the abundances and the faint-end slopes of blue and red satellite galaxies can be interpreted in terms of their formation history, with two distinct modes separated by some characteristic time.

  4. Three years of Swift/BAT Survey of AGN: Reconciling Theory and Observations?

    Energy Technology Data Exchange (ETDEWEB)

    Burlon, D.; /Garching, Max Planck Inst., MPE; Ajello, M.; /SLAC /KIPAC, Menlo Park; Greiner, J.; /Garching, Max Planck Inst., MPE; Comastri, A.; /Muenchen, Tech. U. Universe; Merloni, A.; /Garching, Max Planck Inst., MPE /Muenchen, Tech. U. Universe; Gehrels, N.; /NASA, Goddard

    2011-02-07

    It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still escapes detection. We derive and analyze the absorption distribution using a complete sample of AGN detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGN represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGN is 20{sub -6}{sup +9}%. We proved for the first time (also in the BAT band) that the anti-correlation of the fraction of absorbed AGN and luminosity it tightly connected to the different behavior of the luminosity functions (XLFs) of absorbed and unabsorbed AGN. This points towards a difference between the two subsamples of objects with absorbed AGN being, on average, intrinsically less luminous than unobscured ones. Moreover the XLFs show that the fraction of obscured AGN might also decrease at very low luminosity. This can be successfully interpreted in the framework of a disk cloud outflow scenario as the disappearance of the obscuring region below a critical luminosity. Our results are discussed in the framework of population synthesis models and the origin of the Cosmic X-ray Background.

  5. Isochrones and Luminosity Functions for Old White Dwarfs

    CERN Document Server

    Richer, H B; Limongi, M; Chieffi, A; Straniero, O; Fahlman, G G; Richer, Harvey B.; Hansen, Brad; Limongi, Marco; Chieffi, Alessandro; Straniero, Oscar; Fahlman, Gregory G.

    1999-01-01

    Using a new grid of models of cooling white dwarfs, we calculate isochrones and luminosity functions in the Johnson-Kron/Cousins and HST filter sets for systems containing old white dwarfs. These new models incorporate a non-grey atmosphere which is necessary to properly describe the effects of molecular opacity at the cool temperatures of old white dwarfs. The various functions calculated and extensively tabulated and plotted are meant to be as utilitarian as possible for observers so all results are listed in quantities that observers will obtain. The tables and plots developed should eventually prove critical in interpreting the results of HST's Advanced Camera observations of the oldest white dwarfs in nearby globular clusters, in understanding the results of searches for old white dwarfs in the Galactic halo, and in determining ages for star clusters of all ages using white dwarfs. As a practical application we demonstrate the use of these results by deriving the white dwarf cooling age of the old Galact...

  6. Evolution of Galaxy Luminosity Function Using Photometric Redshifts

    CERN Document Server

    Ramos, B H F; Benoist, C; da Costa, L N; Maia, M A G; Makler, M; Ogando, R L C; de Simoni, F; Mesquita, A A

    2011-01-01

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end we compare LFs obtained using photometric redshifts from the CFHT Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ~4800 galaxies. We find that for z<2, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of CFHTLS comprising ~386000 galaxies to compute the LF of the combined fields and estimate directly the error in the parameters based on field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ~0.7mag from z~1.8 to z~0.3, while the characteristic density phi* increases by a factor of ~4 in the same redshift bin. We use the galaxy classification provided by the templ...

  7. The Luminosity Function of Star Clusters in Spiral Galaxies

    CERN Document Server

    Larsen, S S

    2002-01-01

    Star clusters in 6 nearby spiral galaxies are examined using archive images from HST/WFPC2. The galaxies have previously been studied from the ground and some of them are known to possess rich populations of "young massive clusters" (YMCs). Comparison with the HST images indicates a success-rate of about 75% for the ground-based cluster detections, with typical contaminants being blends or loose groupings of several stars in crowded regions. The luminosity functions (LFs) of cluster candidates identified on the HST images are analyzed and compared with existing data for the Milky Way and the LMC. The LFs are well approximated by power-laws of the form dN(L)/dL ~ L^alpha, with slopes in the range -2.4

  8. The Role of Star Formation and an AGN in Dust Heating of z = 0.3-2.8 Galaxies. I. Evolution with Redshift and Luminosity

    Science.gov (United States)

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric; Yan, Lin; Armus, Lee; Díaz-Santos, Tanio; Stierwalt, Sabrina

    2015-11-01

    We characterize infrared spectral energy distributions of 343 (ultra)luminous infrared galaxies from z = 0.3-2.8. We diagnose the presence of an active galactic nucleus (AGN) by decomposing individual Spitzer mid-IR spectroscopy into emission from star formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGNs, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright S24, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2-1000 μm). We fit the far-IR emission using a two-temperature modified blackbody to measure cold and warm dust temperatures (Tc and Tw). We find that Tc does not depend on mid-IR classification, while Tw shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to LIR. AGNs, composites, and SFGs separate in S8/S3.6 and S250/S24, providing a useful diagnostic for estimating relative amounts of these sources. We estimate that >40% of IR-selected samples host an AGN, even at faint selection thresholds (S24 > 100 μJy). Our decomposition technique and color diagnostics are relevant given upcoming observations with the James Webb Space Telescope.

  9. The long-term X-ray variability properties of AGN in the Lockman Hole region

    OpenAIRE

    Papadakis, I. E.; Chatzopoulos, E.; Athanasiadis, D.; A. Markowitz(University of California, San Diego, United States); Georgantopoulos, I.

    2008-01-01

    We present the results from a detailed X-ray variability analysis of 66 AGN in the Lockman Hole, which have optical spectroscopic identifications. We compare, quantitatively, their variability properties with the properties of local AGN, and we study the "variability-luminosity" relation as a function of redshift, and the "variability-redshift" relation in two luminosity bins. We use archival data from the last 10 XMM observations of the Lockman Hole field to extract light curves in the rest ...

  10. Self-Consistent Models of the AGN and Black Hole Populations: Duty Cycles, Accretion Rates, and the Mean Radiative Efficiency

    OpenAIRE

    Shankar, Francesco; Weinberg, David H.; Miralda-Escude, Jordi

    2007-01-01

    We construct evolutionary models of the populations of AGN and supermassive black holes, in which the black hole mass function grows at the rate implied by the observed luminosity function, given assumptions about the radiative efficiency and the Eddington ratio. We draw on a variety of recent X-ray and optical measurements to estimate the bolometric AGN luminosity function and compare to X-ray background data and the independent estimate of Hopkins et al. (2007) to assess remaining systemati...

  11. The Herschel PEP/HerMES luminosity function - I. Probing the evolution of PACS selected Galaxies to z ≃ 4

    Science.gov (United States)

    Gruppioni, C.; Pozzi, F.; Rodighiero, G.; Delvecchio, I.; Berta, S.; Pozzetti, L.; Zamorani, G.; Andreani, P.; Cimatti, A.; Ilbert, O.; Le Floc'h, E.; Lutz, D.; Magnelli, B.; Marchetti, L.; Monaco, P.; Nordon, R.; Oliver, S.; Popesso, P.; Riguccini, L.; Roseboom, I.; Rosario, D. J.; Sargent, M.; Vaccari, M.; Altieri, B.; Aussel, H.; Bongiovanni, A.; Cepa, J.; Daddi, E.; Domínguez-Sánchez, H.; Elbaz, D.; Förster Schreiber, N.; Genzel, R.; Iribarrem, A.; Magliocchetti, M.; Maiolino, R.; Poglitsch, A.; Pérez García, A.; Sanchez-Portal, M.; Sturm, E.; Tacconi, L.; Valtchanov, I.; Amblard, A.; Arumugam, V.; Bethermin, M.; Bock, J.; Boselli, A.; Buat, V.; Burgarella, D.; Castro-Rodríguez, N.; Cava, A.; Chanial, P.; Clements, D. L.; Conley, A.; Cooray, A.; Dowell, C. D.; Dwek, E.; Eales, S.; Franceschini, A.; Glenn, J.; Griffin, M.; Hatziminaoglou, E.; Ibar, E.; Isaak, K.; Ivison, R. J.; Lagache, G.; Levenson, L.; Lu, N.; Madden, S.; Maffei, B.; Mainetti, G.; Nguyen, H. T.; O'Halloran, B.; Page, M. J.; Panuzzo, P.; Papageorgiou, A.; Pearson, C. P.; Pérez-Fournon, I.; Pohlen, M.; Rigopoulou, D.; Rowan-Robinson, M.; Schulz, B.; Scott, D.; Seymour, N.; Shupe, D. L.; Smith, A. J.; Stevens, J. A.; Symeonidis, M.; Trichas, M.; Tugwell, K. E.; Vigroux, L.; Wang, L.; Wright, G.; Xu, C. K.; Zemcov, M.; Bardelli, S.; Carollo, M.; Contini, T.; Le Févre, O.; Lilly, S.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Zucca, E.

    2013-06-01

    We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z ˜ 4. We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)3.55 ± 0.10 up to z ˜ 2, and ∝ (1 + z)1.62 ± 0.51 at 2 < z ≲ 4) combined with a density evolution (∝(1 + z)-0.57 ± 0.22 up to z ˜ 1 and ∝ (1 + z)-3.92 ± 0.34 at 1 < z ≲ 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ˜ 1, then flattens between z ˜ 1 and z ˜ 3 to decrease at z ≳ 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR-stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (˜20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z < 2.2 range. Sources with mass in the range 10 ≤ log(M/M⊙) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (≳2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand

  12. BLACK HOLE MASS AND EDDINGTON RATIO DISTRIBUTION FUNCTIONS OF X-RAY-SELECTED BROAD-LINE AGNs AT z ∼ 1.4 IN THE SUBARU XMM-NEWTON DEEP FIELD

    International Nuclear Information System (INIS)

    In order to investigate the growth of supermassive black holes (SMBHs), we construct the black hole mass function (BHMF) and Eddington ratio distribution function (ERDF) of X-ray-selected broad-line active galactic nuclei (AGNs) at z ∼ 1.4 in the Subaru XMM-Newton Deep Survey (SXDS) field. A significant part of the accretion growth of SMBHs is thought to take place in this redshift range. Black hole masses of X-ray-selected broad-line AGNs are estimated using the width of the broad Mg II line and 3000 Å monochromatic luminosity. We supplement the Mg II FWHM values with the Hα FWHM obtained from our NIR spectroscopic survey. Using the black hole masses of broad-line AGNs at redshifts between 1.18 and 1.68, the binned broad-line AGN BHMFs and ERDFs are calculated using the Vmax method. To properly account for selection effects that impact the binned estimates, we derive the corrected broad-line AGN BHMFs and ERDFs by applying the maximum likelihood method, assuming that the ERDF is constant regardless of the black hole mass. We do not correct for the non-negligible uncertainties in virial BH mass estimates. If we compare the corrected broad-line AGN BHMF with that in the local universe, then the corrected BHMF at z = 1.4 has a higher number density above 108 M☉ but a lower number density below that mass range. The evolution may be indicative of a downsizing trend of accretion activity among the SMBH population. The evolution of broad-line AGN ERDFs from z = 1.4 to 0 indicates that the fraction of broad-line AGNs with accretion rates close to the Eddington limit is higher at higher redshifts.

  13. The role of star-formation and AGN in dust heating of z = 0.3-2.8 galaxies - I. Evolution with redshift and luminosity

    CERN Document Server

    Kirkpatrick, Allison; Sajina, Anna; Roebuck, Eric; Yan, Lin; Armus, Lee; Diaz-Santos, Tanio; Stierwalt, Sabrina

    2015-01-01

    We characterize infrared spectral energy distributions of 343 (Ultra) Luminous Infrared Galaxies from $z=0.3-2.8$. We diagnose the presence of an AGN by decomposing individual Spitzer mid-IR spectroscopy into emission from star-formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGN, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright $S_{24}$, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2-1000 $\\mu$m). We fit the far-IR emission using a two temperature modified blackbody to measure cold and warm dust temperatures ($T_c$ and $T_w$). We find that $T_c$ does not depend on mid-IR classification, while $T_w$ shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to $L_{\\rm IR}$. AGN, composites...

  14. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Kryukova, E.; Megeath, S. T.; Allen, T. S. [Department of Physics and Astronomy, University of Toledo, Toledo, OH (United States); Gutermuth, R. A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Pipher, J. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Allen, L. E. [National Optical Astronomy Observatories, Tucson, AZ (United States); Myers, P. C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Muzerolle, J. [Space Telescope Science Institute, Baltimore, MD (United States)

    2012-08-15

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 {mu}m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 {mu}m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L{sub Sun} and show a tail extending toward luminosities above 100 L{sub Sun }. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L{sub Sun }. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity

  15. The faint end of the 250 micron luminosity function at z < 0.5

    CERN Document Server

    Wang, L; Bethermin, M; Bourne, N; Cooray, A; Cowley, W; Dunne, L; Dye, S; Eales, S; Farrah, D; Lacey, C; Loveday, J; Maddox, S; Oliver, S; Viero, M

    2016-01-01

    Aims. We aim to study the 250 micron luminosity function (LF) down to much fainter luminosities than achieved by previous efforts. Methods. We developed a modified stacking method to reconstruct the 250 micron LF using optically selected galaxies from the SDSS survey and Herschel maps of the GAMA equatorial fields and Stripe 82. Our stacking method not only recovers the mean 250 micron luminosities of galaxies that are too faint to be individually detected, but also their underlying distribution functions. Results. We find very good agreement with previous measurements in the overlapping luminosity range. More importantly, we are able to derive the LF down to much fainter luminosities (around 25 times fainter) than achieved by previous studies. We find strong positive luminosity evolution \\propto (1 + z)^4.89\\pm1.07 and moderate negative density evolution \\propto (1 + z)^-1.02\\pm0.54 over the redshift range z=[0.02, 0.5].

  16. The Luminosity Function of OB Associations in the Galaxy

    Science.gov (United States)

    McKee, Christopher F.; Williams, Jonathan P.

    1997-02-01

    OB associations ionize the interstellar medium, producing both localized H II regions and diffuse ionized gas. The supernovae resulting from these associations pressurize and stir the interstellar medium. Using Smith, Biermann, & Mezger's compilation of radio H II regions in the Galaxy, and Kennicutt, Edgar, & Hodge's optical study of H II regions in nearby galaxies, we show that the luminosity distribution of giant OB associations in the Galaxy can be fit by a truncated power law of the form \\Nscra(>S)=\\Nscrau[(Su/S)-1], where S is the ionizing photon luminosity, \\Nscra(>S) is the number of associations with a luminosity of at least S, and Su is the upper limit to the distribution. The coefficient \\Nscrau is the number of the most luminous associations, with a luminosity between 0.5Su and Su. For the Galaxy, \\Nscrau=6.1 the fact that the number of the most luminous associations is significantly larger than unity indicates that there is a physical limit to the maximum size of H II regions in the Galaxy. To extend the luminosity distribution to small H II regions, we assume that the birthrate of associations, \\Nscr\\dota(>\\Nscr*), is also a truncated power law, \\Nscr\\dota(>\\Nscr*)~[(\\Nscr*u/\\Nscr*)-1], where \\Nscr* is the number of stars in the association. For large associations, the ionizing luminosity is proportional to the number of stars, S~\\Nscr* for smaller associations, we use both an analytic and a Monte Carlo approach to find the resulting luminosity distribution \\Nscra(>S). H II regions are generally centrally concentrated, with only the dense central regions being bright enough to appear in radio catalogs. Anantharamaiah postulated that radio H II regions have extended envelopes in order to account for diffuse radio recombination line emission in the Galaxy. Some of these envelopes are visible as the ionized ``worms'' discussed by Heiles and coworkers. We estimate that on the average the envelopes of radio H II regions absorb about twice

  17. GAMA/WiggleZ: The 1.4GHz radio luminosity functions of high- and low-excitation radio galaxies and their redshift evolution to z=0.75

    CERN Document Server

    Pracy, Michael; Sadler, Elaine; Croom, Scott; Baldry, Ivan; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael; Couch, Warrick; Davis, Tamara; Drinkwater, Michael; Hopkins, Andrew; Jarvis, Matt; Jelliffe, Ben; Jurek, Russell; Loveday, Jon; Pimbblet, Kevin; Prescott, Matt; Wisniosk, Emily; Woods, David

    2016-01-01

    We present radio Active Galactic Nuclei (AGN) luminosity functions over the redshift range 0.005 < z < 0.75. The sample from which the luminosity functions are constructed is an optical spectroscopic survey of radio galaxies, identified from matched Faint Images of the Radio Sky at Twenty-cm survey (FIRST) sources and Sloan Digital Sky Survey (SDSS) images.The radio AGN are separated into Low Excitation Radio Galaxies (LERGs) and High Excitation Radio Galaxies (HERGs) using the optical spectra. We derive radio luminosity functions for LERGs and HERGs separately in the three redshift bins (0.005 < z < 0.3, 0.3 < z < 0.5 and 0.5 < z <0.75). The radio luminosity functions can be well described by a double power-law. Assuming this double power-law shape the LERG population displays little or no evolution over this redshift range evolving as ~$(1+z)^{0.06}$ assuming pure density evolution or ~ $(1+z)^{0.46}$ assuming pure luminosity evolution. In contrast, the HERG population evolves more r...

  18. The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming Regions

    Science.gov (United States)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; Thilker, David; Calzetti, Daniela; Kennicutt, Robert C.

    2016-08-01

    We present the first study of GALEX far ultra-violet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ˜65,000 star-forming regions (i.e., FUV sources), measure each galaxy's luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. A final sample of 82 galaxies with reliable luminosity functions are used to define these relationships and represent the largest sample of galaxies with the largest range of galaxy properties used to study the connection between luminosity function properties and galaxy environment. We find that α correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities (ΣSFR) tend to have flatter luminosity function slopes. In addition, we find that neither stochastic sampling of the luminosity function in galaxies with low-number statistics nor the effects of blending due to distance can fully account for these trends. We hypothesize that the flatter slopes in high ΣSFR galaxies is due to higher gas densities and higher star formation efficiencies which result in proportionally greater numbers of bright star-forming regions. Finally, we create a composite luminosity function composed of star-forming regions from many galaxies and find a break in the luminosity function at brighter luminosities. However, we find that this break is an artifact of varying detection limits for galaxies at different distances.

  19. GAMA/WiggleZ: the 1.4 GHz radio luminosity functions of high- and low-excitation radio galaxies and their redshift evolution to z = 0.75

    Science.gov (United States)

    Pracy, Michael B.; Ching, John H. Y.; Sadler, Elaine M.; Croom, Scott M.; Baldry, I. K.; Bland-Hawthorn, Joss; Brough, S.; Brown, M. J. I.; Couch, Warrick J.; Davis, Tamara M.; Drinkwater, Michael J.; Hopkins, A. M.; Jarvis, M. J.; Jelliffe, Ben; Jurek, Russell J.; Loveday, J.; Pimbblet, K. A.; Prescott, M.; Wisnioski, Emily; Woods, David

    2016-07-01

    We present radio active galactic nuclei (AGN) luminosity functions over the redshift range 0.005 law. Assuming this double power-law shape the LERG population displays little or no evolution over this redshift range evolving as {˜ } (1+z)^{0.06^{+0.17}_{-0.18}} assuming pure density evolution or {˜ } (1+z)^{0.46^{+0.22}_{-0.24}} assuming pure luminosity evolution. In contrast, the HERG population evolves more rapidly, best fitted by {˜ } (1+z)^{2.93^{+0.46}_{-0.47}} assuming a double power-law shape and pure density evolution. If a pure luminosity model is assumed, the best-fitting HERG evolution is parametrized by {˜ } (1+z)^{7.41^{+0.79}_{-1.33}}. The characteristic break in the radio luminosity function occurs at a significantly higher power (≳1 dex) for the HERG population in comparison to the LERGs. This is consistent with the two populations representing fundamentally different accretion modes.

  20. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    Science.gov (United States)

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-07-01

    We investigate the star-forming properties of 1620 X-ray selected active galactic nuclei (AGN) host galaxies as a function of their specific X-ray luminosity (i.e. X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star formation at high Eddington ratios, which may hint towards `AGN feedback' effects. Star formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{{⊙}} M_{{⊙}}^{-1}). After normalizing for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e. 8-10 per cent versus 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star formation.

  1. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    Science.gov (United States)

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-04-01

    We investigate the star-forming properties of 1620 X-ray selected AGN host galaxies as a function of their specific X-ray luminosity (i.e., X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star-formation at high Eddington ratios, which may hint toward "AGN feedback" effects. Star-formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{⊙} M_{⊙}^{-1}). After normalising for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e., 8-10 per cent vs. 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star-formation.

  2. Dependence of the bright end of galaxy luminosity function on cluster dynamical state

    CERN Document Server

    Wen, Z L

    2014-01-01

    Luminosity function of cluster galaxies provides a fundamental constraint on galaxy evolution in cluster environments. By using the bright member galaxies of a large sample of rich clusters identified from Sloan Digital Sky Survey, we obtain the bright end of composite luminosity functions of cluster galaxies, and study their dependence on cluster dynamical state. After a redshift-evolution correction of absolute magnitude, the luminosity function of member galaxies can be well fitted by a Schechter function when the brightest cluster galaxies (BCGs) are excluded. The absolute magnitudes of BCGs follow a Gaussian function with a characteristic width of about 0.36 mag. We find that the luminosity function of galaxies in more relaxed clusters has a fainter characteristic absolute magnitude (M_{\\ast}), and these clusters have fewer bright non-BCG member galaxies but a brighter BCG. Our results suggest the co-evolution of galaxy population with cluster dynamical state and somewhat support the hierarchical formati...

  3. The Environmental Dependence of the Galaxy Luminosity Function in the ECO Survey

    Science.gov (United States)

    Andrews, Hayley; Andreas A. Berlind, Victor Calderon, Kathleen D. Eckert, Sheila J. Kannappan, Amanda J. Moffett, David V. Stark

    2016-01-01

    We study the environmental dependence of the galaxy luminosity function in the ECO survey and compare it with models that associate galaxies with dark matter halos. Specifically, we quantify the environment of each galaxy in the ECO survey using an Nth nearest neighbor distance metric, and we measure how the galaxy luminosity distribution varies from low density to high density environments. As expected, we find that luminous galaxies preferentially populate high density regions, while low luminosity galaxies preferentially populate lower density environments. We investigate whether this trend can be explained simply by the correlation of galaxy luminosity and dark matter halo mass combined with the environmental dependence of the halo mass function. In other words, we test the hypothesis that the luminosity of a galaxy depends solely on the mass of its dark matter halo and does not exhibit a residual dependence on the halo's larger environment. To test this hypothesis, we first construct mock ECO catalogs by populating dark matter halos in an N-body simulation with galaxies using a model that preserves the overall clustering strength of the galaxy population. We then assign luminosities to the mock galaxies using physically motivated models that connect luminosity to halo mass and are constrained to match the global ECO luminosity function. Finally, we impose the radial and angular selection functions of the ECO survey and repeat our environmental analysis on the mock catalogs. Though our mock catalog luminosity functions display similar qualitative trends as those from the ECO data, the trends are not in agreement quantitatively. Our results thus suggest that the simple models used to build the mocks are incomplete and that galaxy luminosity is possibly correlated with the larger scale density field.

  4. A Close Examination of the Measurement and Parametrization of Luminosity Functions in an Expanding Universe

    CERN Document Server

    Lake, S E; Tsai, C -W; Lam, A

    2016-01-01

    The astronomy community has at its disposal a large back catalog of public spectroscopic galaxy redshift surveys that can be used for the measurement of luminosity functions. Utilizing the back catalog with new photometric surveys to maximum efficiency requires modeling the color selection bias imposed on selection of target galaxies by flux limits at multiple wavelengths. The likelihood derived herein can address, in principle, all possible color selection biases through the use of a generalization of the luminosity function, $\\Phi(L)$, over the space of all spectra: the spectro-luminosity functional, $\\Psi[L_\

  5. SWIFT BAT Survey of AGN

    Science.gov (United States)

    Tueller, J.; Mushotzky, R. F.; Barthelmy, S.; Cannizzo, J. K.; Gehrels, N.; Markwardt, C. B.; Skinner, G. K.; Winter, L. M.

    2008-01-01

    We present the results1 of the analysis of the first 9 months of data of the Swift BAT survey of AGN in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGN) of 130 objects detected at [b] > 15deg and with significance > 4.8-delta. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the logN - log S distribution, and find the slope to be 1.42+/-0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity logL*(ergs/s)= 43.85+/-0.26. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGN above 10(exp 41) erg/s of 2.4x10(exp -3) Mpc(sup -3), which is about 10% of the total luminous local galaxy density above M* = -19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log nH is essentially flat from nH = 10(exp 20)/sq cm to 10(exp 24)/sq cm, with 50% of the objects having column densities of less than 10(exp 22)/sq cm. BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log nH > 22.

  6. The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction

    CERN Document Server

    Martini, Paul; Brodwin, M; Stanford, S A; Gonzalez, Anthony H; Bautz, M; Hickox, R C; Stern, D; Eisenhardt, P R; Galametz, A; Norman, D; Jannuzi, B T; Dey, A; Murray, S; Jones, C; Brown, M J I

    2013-01-01

    The fraction of cluster galaxies that host luminous AGN is an important probe of AGN fueling processes, the cold ISM at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M >= 10^{14} Msun) at 1= 10^{44} erg/s. This fraction is measured relative to all cluster galaxies more luminous than M*_{3.6}(z)+1, where M*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6um bandpass. The cluster AGN fraction is 30 times greater than the 3sigma upper limit on the value for AGN of similar luminosity at z~0.25, as well as more than an order of magnitude greater than the AGN fraction at z~0.75. AGN with L_{X,H} >= 10^{43} erg/s exhibit similarly pronounced evolution with redshift. In contrast with the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field...

  7. The ensemble optical variability of type-1 AGN in the Sloan Digital Sky Survey Data Release 7

    Science.gov (United States)

    Gallastegui-Aizpun, Unai; Sarajedini, Vicki L.

    2014-11-01

    We use a sample of over 5000 active galactic nuclei (AGN) with extended morphologies at z function of rest-frame time lag and AGN luminosity with the aim of investigating these parameter relationships at lower luminosities than previously studied. We compare photometry from imaging data with spectrophotometry obtained weeks to years later in the Sloan g, r, and i bands. We employ quasar and galaxy eigenspectra fitting to separate the AGN and host galaxy components. A strong correlation between the variability amplitude and rest-frame time lag is observed, in agreement with quasar structure functions but extending to AGN several magnitudes fainter than previously studied. The structure function slopes for our fainter AGN sample are slightly shallower than those found in quasars studies. An anticorrelation with luminosity is clearly detected, with lower luminosity AGN displaying greater variability amplitudes. We demonstrate for the first time that this anticorrelation extends to AGN as faint as MAGNi ˜ -18.5, with a slight trend towards shallower slopes at luminosities fainter than MAGNi ˜ -20.2.

  8. The PEP Survey: Infrared Properties of Radio-Selected AGN

    CERN Document Server

    Magliocchetti, M; Rosario, D; Berta, S; Floc'h, E Le; Magnelli, B; Pozzi, F; Riguccini, L; Santini, P

    2014-01-01

    By exploiting the VLA-COSMOS and the Herschel-PEP surveys, we investigate the Far Infrared (FIR) properties of radio-selected AGN. To this purpose, from VLA-COSMOS we considered the 1537, F[1.4 GHz]>0.06 mJy sources with a reliable redshift estimate, and sub-divided them into star-forming galaxies and AGN solely on the basis of their radio luminosity. The AGN sample is complete with respect to radio selection at all z<~3.5. 832 radio sources have a counterpart in the PEP catalogue. 175 are AGN. Their redshift distribution closely resembles that of the total radio-selected AGN population, and exhibits two marked peaks at z~0.9 and z~2.5. We find that the probability for a radio-selected AGN to be detected at FIR wavelengths is both a function of radio power and redshift, whereby powerful sources are more likely to be FIR emitters at earlier epochs. This is due to two distinct effects: 1) at all radio luminosities, FIR activity monotonically increases with look-back time and 2) radio activity of AGN origin i...

  9. Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations

    CERN Document Server

    Ueda, Yoshihiro; Hasinger, Guenther; Miyaji, Takamitsu; Watson, Michael G

    2014-01-01

    We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5--2 keV) and/or hard ($>2$ keV) band. We utilize a maximum likelihood method to reproduce the count-rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broad band spectra of AGNs including reflection components from tori based on the luminosity and redshift dependent unified scheme. We find that the shape of the XLF at $z \\sim 1-3$ is significantly different from that in the local universe, for which the luminosity dependent density evolution model gives much better description...

  10. A Multi-wavelength Survey of AGN in Massive Clusters: AGN Detection and Cluster AGN Fraction

    OpenAIRE

    Klesman, Alison J.; Sarajedini, Vicki L.

    2012-01-01

    We aim to study the effect of environment on the presence and fuelling of Active Galactic Nuclei (AGN) in massive galaxy clusters. We explore the use of different AGN detection techniques with the goal of selecting AGN across a broad range of luminosities, AGN/host galaxy flux ratios, and obscuration levels. From a sample of 12 galaxy clusters at redshifts 0.5 < z < 0.9, we identify AGN candidates using optical variability from multi-epoch HST imaging, X-ray point sources in Chandra images, a...

  11. The European Large Area ISO Survey IV the preliminary 90 micron luminosity function

    CERN Document Server

    Serjeant, S; Oliver, S; Surace, C; Heraudeau, P; Linden-Voernle, M J D; Gruppioni, C; La Franca, F; Rigopoulou, D; Morel, T; Crockett, H; Sumner, T J; Rowan-Robinson, M; Graham, M

    2000-01-01

    We present the luminosity function of 90um selected galaxies from the European Large Area ISO Survey (ELAIS), extending to z=0.3. Their luminosities are in the range 10^9 = 100mJy database, we found optical, 15um or 1.4GHz identifications for 24 (65%). We have obtained 2dF and UK Schmidt FLAIR spectroscopy of 89% of IDs to rigid multivariate flux limits. We construct a luminosity function assuming (a) our spectroscopic subset is an unbiased sparse sample, and (b) there are no galaxies which would not be represented in our spectroscopic sample at {\\it any} redshift. We argue that we can be confident of both assumptions. We find the luminosity function is well-described by the local 100um luminosity function of Rowan-Robinson, Helou & Walker (1987). {\\it Assuming} this local normalisation, we derive luminosity evolution of (1+z)^{2.45\\pm0.85} (95% confidence). We argue that star formation dominates the bolometric luminosities of these galaxies and we derive comoving star formation rates in broad agreement w...

  12. The Faint Optical Stellar Luminosity Function in the Ursa Minor Dwarf Spheroidal Galaxy

    CERN Document Server

    Feltzing, S; Wyse, R F G; Feltzing, Sofia; Gilmore, Gerard; Wyse, Rosemary F.G.

    1999-01-01

    Analyses of their internal stellar kinematics imply that the dwarf spheroidal (dSph) companion galaxies to the Milky Way are among the most dark-matter dominated systems known. Should there be significant dark matter in the form of faint stars in these systems, the stellar luminosity function must be very different from that of a similar metallicity globular cluster, for which there is no evidence for dark matter. We present the faint stellar luminosity function in the Ursa Minor dSph, down to a luminosity corresponding to roughly 0.45 M_sun, derived from new deep HST/WFPC2 data. We find a remarkable similarity between this luminosity function, and inferred initial mass function, and that of the globular cluster M92, a cluster of similar age and metallicity to the Ursa Minor dSph.

  13. Limits on the neutrino magnetic dipole moment from the luminosity function of hot white dwarfs

    CERN Document Server

    Bertolami, Marcelo Miguel Miller

    2014-01-01

    Recent determinations of the white dwarf luminosity function (WDLF) from very large surveys have extended our knowledge of the WDLF to very high luminosities. This, together with the availability of new full evolutionary white dwarf models that are reliable at high luminosities, have opened the possibility of testing particle emission in the core of very hot white dwarfs, where neutrino processes are dominant. We use the available WDLFs from the Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey to constrain the value of the neutrino magnetic dipole moment ($\\mu_\

  14. Testing Fundamental Particle Physics with the Galactic White Dwarf Luminosity Function

    CERN Document Server

    Bertolami, Marcelo M Miller; Althaus, Leandro G; Isern, Jordi

    2014-01-01

    Recent determinations of the white dwarf luminosity function (WDLF) from very large surveys have extended our knowledge of the WDLF to very high luminosities. It has been shown that the shape of the luminosity function of white dwarfs (WDLF) is a powerful tool to test the possible properties and existence of fundamental weakly interacting subelectronvolt particles. This, together with the availability of new full evolutionary white dwarf models that are reliable at high luminosities, have opened the possibility of testing particle emission in the core of very hot white dwarfs. We use the available WDLFs from the Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey to constrain the values of the neutrino magnetic dipole moment ($\\mu_\

  15. Testing Fundamental Particle Physics with the Galactic White Dwarf Luminosity Function

    Science.gov (United States)

    Miller Bertolami, M. M.; Melendez, B. E.; Althaus, L. G.; Isern, J.

    2015-06-01

    Recent determinations of the white dwarf luminosity function (WDLF) from very large surveys have extended our knowledge of the WDLF to very high luminosities. It has been shown that the shape of the luminosity function of white dwarfs (WDLF) is a powerful tool to test the possible properties and existence of fundamental weakly interacting subelectronvolt particles. This, together with the availability of new full evolutionary white dwarf models that are reliable at high luminosities, have opened the possibility of testing particle emission in the core of very hot white dwarfs. We use the available WDLFs from the Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey to constrain the values of the neutrino magnetic dipole moment (μν) and the axion-electron coupling constant (gae) of DFSZ-axions.

  16. Cosmic Reionization On Computers: The Faint End of the Galaxy Luminosity Function

    Energy Technology Data Exchange (ETDEWEB)

    Gnedin, Nickolay Y. [Fermilab

    2016-07-01

    Using numerical cosmological simulations completed under the "Cosmic Reionization On Computers" (CROC) project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at $z\\geq 6$. A commonly used Schechter function approximation with the magnitude cut at $M_{\\rm CUT}\\sim-13$ provides a reasonable fit to the actual luminosity function of simulated galaxies. When the Schechter functional form is forced on the luminosity functions from the simulations, the magnitude cut $M_{\\rm CUT}$ is found to vary between $-12$ and $-14$ with a mild redshift dependence. An analytical model of reionization from Madau, Haardt & Rees (1997), as used by Robertson et al. (2015), provides a good description of the simulated results, but only if the redshift dependence of the effective escape fraction (induced by physical processes not captured by the Madau, Haardt & Rees model) is accounted for.

  17. Improved AGN light curve analysis with the z-transformed discrete correlation function

    CERN Document Server

    Alexander, Tal

    2013-01-01

    The cross-correlation function (CCF) is commonly employed in the study of AGN, where it is used to probe the structure of the broad line region by line reverberation, to study the continuum emission mechanism by correlating multi-waveband light curves and to seek correlations between the variability and other AGN properties. The z -transformed discrete correlation function (ZDCF) is a new method for estimating the CCF of sparse, unevenly sampled light curves. Unlike the commonly used interpolation method, it does not assume that the light curves are smooth and it does provide errors on its estimates. The ZDCF corrects several biases of the discrete correlation function method of Edelson & Krolik (1988) by using equal population binning and Fisher's z -transform. These lead to a more robust and powerful method of estimating the CCF of sparse light curves of as few as 12 points. Two examples of light curve analysis with the ZDCF are presented. 1) The ZDCF estimate of the auto-correlation function is used to...

  18. Quenching Star Formation: Can AGN Do the Trick?

    CERN Document Server

    Gabor, Jared M

    2009-01-01

    We post-process galaxy star formation histories in cosmological hydrodynamics simulations to test quenching mechanisms associated with AGN. By comparing simulation results to color-magnitude diagrams and luminosity functions of SDSS galaxies, we examine whether "quasar mode" or "radio mode" AGN feedback can yield a realistic red sequence. Both cases yield red sequences distinct from the blue cloud, decent matches to the luminosity function, and galaxies that are too blue by about 0.1 magnitudes in g-r. Our merger-based prescription for quasar mode feedback, however, yields a red sequence build-up inconsistent with observations: the luminosity function lacks a characteristic knee, and the brightest galaxies include a small number of young stars.

  19. Models of high redshift luminosity functions and galactic outflows: The dependence on halo mass function

    CERN Document Server

    Samui, Saumyadip; Srianand, Raghunathan

    2009-01-01

    The form of the halo mass function is a basic ingredient in any semi-analytical galaxy formation model. We study the existing forms of the mass functions in the literature and compare their predictions for semi-analytical galaxy formation models. Two methods are used in the literature to compute the net formation rate of halos, one by simply taking the derivative of the halo mass function and the other using the prescription due to Sasaki (1994). For the Press-Schechter (PS) mass function, we compare various model predictions, using these two methods. However, as the Sasaki formalism cannot be easily generalized for other mass functions, we use the derivative while comparing model predictions of different mass functions. We show that the reionization history and UV luminosity function of Lyman break galaxies (LBGs) predicted by the PS mass function differs from those using any other existing mass function, like Sheth-Tormen (ST) mass function.In particular the reionization efficiency of molecular cooled halos...

  20. The Galaxy Cluster Mid-Infrared Luminosity Function at 1.3

    CERN Document Server

    Wylezalek, Dominika; De Breuck, Carlos; Stern, Daniel; Brodwin, Mark; Galametz, Audrey; Gonzalez, Anthony H; Jarvis, Matt; Hatch, Nina; Seymour, Nick; Stanford, Spencer A

    2014-01-01

    We present 4.5 {\\mu}m luminosity functions for galaxies identified in 178 candidate galaxy clusters at 1.3 1.3. The luminosity functions are derived for different redshift and richness bins, and the IRAC imaging reaches depths of m*+2, allowing us to measure the faint end slopes of the luminosity functions. We find that {\\alpha} = -1 describes the luminosity function very well in all redshifts bins and does not evolve significantly. This provides evidence that the rate at which the low mass galaxy population grows through star formation, gets quenched and is replenished by in-falling field galaxies does not have a major net effect on the shape of the luminosity function. Our measurements for m* are consistent with passive evolution models and high formation redshifts z_f ~ 3. We find a slight trend towards fainter m* for the richest clusters, implying that the most massive clusters in our sample could contain older stellar populations, yet another example of cosmic downsizing. Modelling shows that a contribu...

  1. The Planetary Nebulae Luminosity Function and distances to Virgo, Hydra I and Coma clusters

    CERN Document Server

    Arnaboldi, Magda; Gerhard, Ortwin; Okamura, S

    2012-01-01

    The luminosity function of planetary nebulae populations in galaxies within 10-15 Mpc distance has a cut-off at bright magnitudes and a functional form that is observed to be invariant in different galaxy morphological types. Thus it is used as a secondary distance indicator in both early and late-type galaxies. Recent deep surveys of planetary nebulae populations in brightest cluster galaxies (BCGs) seem to indicate that their luminosity functions deviate from those observed in the nearby galaxies. We discuss the evidence for such deviations in Virgo, and indicate which physical mechanisms may alter the evolution of a planetary nebula envelope and its central star in the halo of BCGs. We then discuss preliminary results for distances for the Virgo, Hydra I and Coma clusters based on the observed planetary nebulae luminosity functions.

  2. A search for X-ray reprocessing echoes in the power spectral density functions of AGN

    CERN Document Server

    Emmanoulopoulos, D; Epitropakis, A; Pecháček, T; Dovčiak, M; McHardy, I M

    2016-01-01

    We present the results of a detailed study of the X-ray power spectra density (PSD) functions of twelve X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection occurs in the inner part of the accretion disc of AGN, the X-ray reflection component should be a filtered echo of the X-ray continuum signal and should be equal to the convolution of the primary emission with the response function of the disc. Our primary objective is to search for these reflection features in the 5-7 keV (iron line) and 0.5-1 keV (soft) bands, where the X-ray reflection fraction is expected to be dominant. We fit to the observed periodograms two models: a simple bending power law model (BPL) and a BPL model convolved with the transfer function of the accretion disc assuming the lamp-post geometry and X-ray reflection from a homogeneous disc. We d...

  3. Luminosity Functions of Spitzer Identified Protostars in Nine Nearby Molecular Clouds

    CERN Document Server

    Kryukova, E; Gutermuth, R A; Pipher, J; Allen, T S; Allen, L E; Myers, P C; Muzerolle, J

    2012-01-01

    We identify protostars in Spitzer surveys of nine star-forming molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine photometry from 2MASS J, H, and Ks bands and Spitzer IRAC and MIPS 24 micron bands to create 1 - 24 micron spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities (Lbol), we derive a relationship between Lbol, L_MIR (integrated from 1 - 24 microns), and SED slope. Estimations of Lbol for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high mass star forming clouds peak near 1 Lsun and show a tail extending ...

  4. The Galaxy Luminosity Functions down to M~-10 in the Hydra I Cluster

    CERN Document Server

    Yamanoi, H; Hamabe, M; Yagi, M; Okamura, S; Iye, M; Shimasaku, K; Doi, M; Komiyama, Yu; Furusawa, H

    2007-01-01

    We study the galaxy population in the central region and a region about 0.6 Mpc away from the center of the Hydra I cluster in B- and Rc-bands down to M~-10 using the Subaru Suprime-Cam photometry. We find that the luminosity function of the entire population has a slightly steeper slope (alpha~-1.6) in the range of -20-14) increases in the cluster center as well as bright galaxies. The Hydra I cluster is dominated by red dwarfs and the luminosity function shows a significant upturn at M~-16 as is seen in several other nearby clusters, but not in the field. This upturn and the variation in the faint-end slope of the luminosity function may be caused by the cluster environment or the evolution history of individual clusters.

  5. Triggering optical AGN: the need for cold gas, and the indirect roles of galaxy environment and interactions

    CERN Document Server

    Sabater, J; Heckman, T M

    2014-01-01

    We present a study of the prevalence and luminosity of Active Galactic Nuclei (AGN; traced by optical spectra) as a function of both environment and galaxy interactions. For this study we used a sample of more than 250000 galaxies drawn from the Sloan Digital Sky Survey and, crucially, we controlled for the effect of both stellar mass and central star formation activity. Once these two factors are taken into account, the effect of the local density of galaxies and of one-on-one interactions is minimal in both the prevalence of AGN activity and AGN luminosity. This suggests that the level of nuclear activity depends primarily on the availability of cold gas in the nuclear regions of galaxies and that secular processes can drive the AGN activity in the majority of cases. Large scale environment and galaxy interactions only affect AGN activity in an indirect manner, by influencing the central gas supply.

  6. The HerMES sub-millimetre local and low-redshift luminosity functions

    CERN Document Server

    Marchetti, L; Franceschini, A; Arumugam, V; Aussel, H; Bethermin, M; Bock, J; Boselli, A; Buat, V; Burgarella, D; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Farrah, D; Feltre, A; Glenn, J; Griffin, M; Hatziminaoglou, E; Heinis, S; Ibar, E; Ivison, R J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rigopoulou, D; Roseboom, I G; Rowan-Robinson, M; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Symeonidis, M; Valtchanov, I; Viero, M; Wang, L; Wardlow, J; Xu, C K; Zemcov, M

    2015-01-01

    We used wide area surveys over 39 deg$^2$ by the HerMES collaboration, performed with the Herschel Observatory SPIRE multi-wavelength camera, to estimate the low-redshift, $0.02luminosity functions (LFs) of galaxies at 250, 350 and 500$\\,\\mu$m. SPIRE flux densities were also combined with Spitzer photometry and multi-wavelength archival data to perform a complete SED fitting analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric infrared (8-1000$\\,\\mu$m) luminosity functions and their low-$z$ evolution from a combination of statistical estimators. Integration of the latter prompted us to also compute the local luminosity density (LLD) and the comoving star formation rate density (SFRD) for our sources, and to compare them with theoretical predictions of galaxy formation models. The luminosity functions show significant and rapid luminosity evolution already at low redshifts, $0.02

  7. Dark-ages reionization & galaxy formation simulation IV: UV luminosity functions of high-redshift galaxies

    CERN Document Server

    Liu, Chuanwu; Angel, P W; Duffy, Alan R; Geil, Paul M; Poole, Gregory B; Mesinger, Andrei; Wyithe, J Stuart B

    2015-01-01

    In this paper we present calculations of the UV luminosity function predictions from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project, which combines N-body, semi-analytic and semi-numerical modeling designed to study galaxy formation during the Epoch of Reionization. Using galaxy formation physics including supernova feedback, the model naturally reproduces the UV LFs for high-redshift star-forming galaxies from $z{\\sim}5$ through to $z{\\sim}10$. We investigate the predicted luminosity-star formation rate (SFR) relation, finding that variable SFR histories of galaxies result in a scatter around the mean relation of $0.1$-$0.3$ dex depending on UV luminosity. We find close agreement between the model and observationally derived SFR functions. We use our predicted luminosities to investigate the luminosity function below current detection limits, and the ionizing photon budget for reionization. We predict that the slope of the UV LF remains steep below cu...

  8. The ESO Slice Project (ESP) galaxy redshift survey. II. The luminosity function and mean galaxy density.

    Science.gov (United States)

    Zucca, E.; Zamorani, G.; Vettolani, G.; Cappi, A.; Merighi, R.; Mignoli, M.; Stirpe, G. M.; MacGillivray, H.; Collins, C.; Balkowski, C.; Cayatte, V.; Maurogordato, S.; Proust, D.; Chincarini, G.; Guzzo, L.; Maccagni, D.; Scaramella, R.; Blanchard, A.; Ramella, M.

    1997-10-01

    The ESO Slice Project (ESP) is a galaxy redshift survey we have recently completed as an ESO Key-Project over about 23 square degrees, in a region near the South Galactic Pole. The survey is nearly complete to the limiting magnitude b_J_=19.4 and consists of 3342 galaxies with reliable redshift determination. The ESP survey is intermediate between shallow, wide angle samples and very deep, one-dimensional pencil beams: spanning a volume of ~5x10^4^h^-3^Mpc^3^ at the sensitivity peak (z~0.1), it provides an accurate determination of the "local" luminosity function and the mean galaxy density. We find that, although a Schechter function (with α=-1.22, M^*^_bJ_=-19.61+5logh and φ^*^=0.020h^3^/Mpc^3^) is an acceptable representation of the luminosity function over the entire range of magnitudes (M_bJ_=-17+5logh. Such a steepening at the faint end of the luminosity function, well fitted by a power law with slope β~-1.6, is almost completely due to galaxies with emission lines: in fact, dividing our galaxies into two samples, i.e. galaxies with and without emission lines, we find significant differences in their luminosity functions. In particular, galaxies with emission lines show a significantly steeper slope and a fainter M^*^. The amplitude and the α and M^*^ parameters of our luminosity function are in good agreement with those of the AUTOFIB redshift survey (Ellis et al. 1996). Vice-versa, our amplitude is significantly higher, by a factor ~1.6 at M~M^*^, than that found for both the Stromlo-APM (Loveday et al. 1992) and the Las Campanas (Lin et al. 1996) redshift surveys. Also the faint end slope of our luminosity function is significantly steeper than that found in these two surveys. The galaxy number density for M_bJ_blue luminosity densities in these three cases are ρ_LUM_=(2.0, 2.2, 2.3)x10^8^hLsun_/Mpc^3^, respectively. Large over- and under- densities are clearly seen in our data. In particular, we find evidence for a "local" under-density (n~0.5n

  9. Three years Swift-BAT Survey of AGN: reconciling theory and observations?

    CERN Document Server

    Burlon, D; Greiner, J; Comastri, A; Merloni, A; Gehrels, N; .,

    2010-01-01

    It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still escapes detection. We derive and analyze the absorption distribution using a complete sample of AGN detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGN represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGN is 20$^{+9}_{-6}$%. We proved for the first time (also in the BAT band) that the anti-correlation of the fraction of absorbed AGN and luminosity it tightly connected to the different behavior of the luminosity functions (XLFs) of absorbed and unabsorbed AGN. This points towards a difference between the two subsamples of objects with absorbed AGN being, on average, intri...

  10. Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Luminosity Functions and Density Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Muzzin, Adam; Yee, H.K.C.; /Toronto U., Astron. Dept.; Hall, Patrick B.; /York U., Canada; Ellingson, E.; /Colorado U., CASA; Lin, Huan; /Fermilab

    2006-12-01

    We present K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters. The extensive spectroscopic dataset available for these clusters allows us to determine the cluster K-band luminosity function and density profile without the need for statistical background subtraction. The luminosity density and number density profiles can be described by NFW models with concentration parameters of c{sub l} = 4.28 {+-} 0.70 and c{sub g} = 4.13 {+-} 0.57 respectively. Comparing these to the dynamical mass analysis of the same clusters shows that the galaxy luminosity and number density profiles are similar to the dark matter profile, and are not less concentrated like in local clusters. The luminosity functions show that the evolution of K. over the redshift range 0.2 < z < 0.5 is consistent with a scenario where the majority of stars in cluster galaxies form at high-redshift (z{sub f} > 1.5) and evolve passively thereafter. The best-fit for the faint-end slope of the luminosity function is {alpha} = -0.84 {+-} 0.08, which indicates that it does not evolve between z = 0 and z = 0.3. Using Principal Component Analysis of the spectra we classify cluster galaxies as either star-forming/recently-star-forming (EM+BAL) or non-star forming (ELL) and compute their respective luminosity functions. The faint-end slope of the ELL luminosity function is much shallower than for the EM+BAL galaxies at z = 0.3, and suggests the number of faint ELL galaxies in clusters decreases by a factor of {approx} 3 from z = 0 to z = 0.3. The redshift evolution of K* for both EM+BAL and ELL types is consistent with a passively evolving stellar population formed at high-redshift. Passive evolution in both classes, as well as the total cluster luminosity function, demonstrates that the bulk of the stellar population in all bright cluster galaxies is formed at high-redshift and subsequent transformations in morphology/color/spectral-type have little effect on the total stellar

  11. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    CERN Document Server

    Takeuchi, Tsutomu T

    2010-01-01

    We show an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient $|\\rho| <1/3 $), the Farlie-Gumbel-Morgenstern (FGM) copula provides an intuitive and natural way for constructing such a bivariate DF. When the linear correlation is stronger, the FGM copula cannot work anymore. In this case, we propose to use a Gaussian copula, which connects two given marginals and directly related to the linear correlation coefficient between two variables. Using the copulas, we constructed the BLFs and discuss its statistical properties. Especially, we focused on the FUV--FIR BLF, since these two luminosities are related to the star formation (SF) activity. Though both the FUV and FIR are related to the SF activity, the univariate LFs have a very ...

  12. The average 0.5-200 keV spectrum of local active galactic nuclei and a new determination of the 2-10 keV luminosity function at z \\approx 0

    CERN Document Server

    Ballantyne, D R

    2013-01-01

    The broadband X-ray spectra of AGNs contains information about the nuclear environment from Schwarzschild radii scales to distances of ~1 pc. In addition, the average shape of the X-ray spectrum is an important input into X-ray background synthesis models. Here, local (z \\approx 0) AGN luminosity functions (LFs) in five energy bands are used as a low-resolution, luminosity-dependent X-ray spectrometer in order to constrain the average AGN X-ray spectrum between 0.5 and 200 keV. The 15-55 keV LF measured by Swift-BAT is assumed to be the best determination of the local LF, and then a spectral model is varied to determine the best fit to the 0.5-2 keV, 2-10 keV, 3-20 keV and 14-195 keV LFs. The spectral model consists of a Gaussian distribution of power-laws with a mean photon-index and cutoff energy E_cut, as well as contributions from distant and disc reflection. The reflection strength is parameterised by varying the Fe abundance relative to solar, A_Fe, and requiring a specific Fe K equivalent width (EW). ...

  13. Galaxy UV-luminosity Function and Reionisation Constraints on Axion Dark Matter

    CERN Document Server

    Bozek, Brandon; Silk, Joseph; Wyse, Rosemary F G

    2014-01-01

    If the dark matter (DM) were composed of axions, then structure formation in the Universe would be suppressed below the axion Jeans scale. Using an analytic model for the halo mass function of a mixed dark matter model with axions and CDM, combined with the abundance-matching technique, we construct the UV luminosity function. Axions suppress high-$z$ galaxy formation and the UV-luminosity function is truncated at a faintest limiting magnitude. From the UV-luminosity function, we predict the reionisation history of the universe and find that axion dark matter causes reionisation to occur at lower redshift. We search for evidence of axions using the Hubble ultra-deep field UV-luminosity function in the redshift range $z=6$ to $10$, and the optical depth to reionisation, $\\tau$, as measured from CMB polarisation. All probes we consider consistently exclude $m_a\\lesssim 10^{-23}\\text{ eV}$ from contributing more than half of the DM, with our strongest constraint ruling this model out at more than $8\\sigma$ signi...

  14. Critical analysis of the luminosity functions per galaxy type measured from redshift surveys

    CERN Document Server

    De Lapparent, V

    2003-01-01

    [ABRIDGED] I perform a detailed comparison of the shape of the optical luminosity functions as a function of galaxy class and filter, which have been obtained from redshift surveys with an effective depth ranging from z~0.01 to z~0.6. This analysis is based on the M* and alpha Schechter parameters. I provide complete tables of all existing measurements, converted into the UBVRcIc Johnson-Cousins system wherever necessary. By using as reference the intrinsic luminosity functions per morphological type measured from local galaxy concentrations (Jerjen et al 1997), I establish that the variations in the luminosity functions from survey to survey and among the galaxy classes are related to the criteria for galaxy classification used in the surveys, as these determine the amount of mixing of the morphological types within a given class. When using a spectral classification with inaccurate spectrophotometric calibrations, the luminosity functions are biased by type contamination with a smooth variation from type to...

  15. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    CERN Document Server

    Bernhard, E; Daddi, E; Ciesla, L; Schreiber, C

    2016-01-01

    We investigate the star-forming properties of 1620 X-ray selected AGN host galaxies as a function of their specific X-ray luminosity (i.e., X-ray luminosity per unit host stellar mass) -- a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star-formation at high Eddington ratios, which may hint toward "AGN feedback" effects. Star-formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning $0.01 \\lesssim L_{\\rm X}/M_{\\ast} \\lesssim 100~L_{\\odot} ~M_{\\odot}^{-1}$). After normalising for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This sugges...

  16. The 60 Month All-Sky Burst Alert Telescope Survey of Active Galactic Nucleus and the Anisotropy of Nearby AGNs

    Science.gov (United States)

    Ajello, M.; Alexander, D. M.; Greiner, J.; Madejeski, G. M.; Gehrels, N.; Burlon, D.

    2014-01-01

    Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of approx. 2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent approx. 5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to approx. 10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9(+4.1/-2.9)× 10(exp -5)/cubic Mpc for objects with a de-absorbed luminosity larger than 2 × 10(exp 42) erg / s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (much < 85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions..

  17. Galaxy and Mass Assembly (GAMA): maximum likelihood determination of the luminosity function and its evolution

    CERN Document Server

    Loveday, J; Baldry, I K; Bland-Hawthorn, J; Brough, S; Brown, M J I; Driver, S P; Kelvin, L S; Phillipps, S

    2015-01-01

    We describe modifications to the joint stepwise maximum likelihood method of Cole (2011) in order to simultaneously fit the GAMA-II galaxy luminosity function (LF), corrected for radial density variations, and its evolution with redshift. The whole sample is reasonably well-fit with luminosity (Qe) and density (Pe) evolution parameters Qe, Pe = 1.0, 1.0 but with significant degeneracies characterized by Qe = 1.4 - 0.4Pe. Blue galaxies exhibit larger luminosity density evolution than red galaxies, as expected. We present the evolution-corrected r-band LF for the whole sample and for blue and red sub-samples, using both Petrosian and Sersic magnitudes. Petrosian magnitudes miss a substantial fraction of the flux of de Vaucouleurs profile galaxies: the Sersic LF is substantially higher than the Petrosian LF at the bright end.

  18. Results from the First INTEGRAL AGN Catalogue

    CERN Document Server

    Beckmann, V; Shrader, C R; Gehrels, N

    2005-01-01

    We present results based on the first INTEGRAL AGN catalogue. The catalogue includes 42 AGN, of which 10 are Seyfert 1, 17 are Seyfert 2, and 9 are intermediate Seyfert 1.5. The fraction of blazars is rather small with 5 detected objects, and only one galaxy cluster and no star-burst galaxies have been detected so far. The sample consists of bright (fx > 5e-12 erg/cm**2/s), low luminosity (L = 2e43 erg/s), local (z = 0.020) AGN. Although the sample is not flux limited, we find a ratio of obscured to unobscured AGN of 1.5 - 2.0, consistent with luminosity dependent unified models for AGN. Only four Compton-thick AGN are found in the sample. This implies that the missing Compton-thick AGN needed to explain the cosmic hard X-ray background would have to have lower fluxes than discovered by INTEGRAL so far.

  19. Sub-mm Emission Line Deep Fields: CO and [CII] Luminosity Functions out to z = 6

    CERN Document Server

    Popping, Gergö; Decarli, Roberto; Spaans, Marco; Somerville, Rachel S; Trager, Scott C

    2016-01-01

    Now that ALMA is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. Deep fields are ideal to study the luminosity function of sub-mm emission lines, ultimately tracing the atomic and molecular gas properties of galaxies. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J=1-0 up to CO J=6-5 and [CII] at redshifts z=0-6. We find that: 1) our model correctly reproduces the CO and [CII] emission of low- and high-redshift galaxies and reproduces the available constraints on the CO luminosity function at z1.5 and the CO luminosity of individual galaxies at intermediate redshifts. We argue that this is driven by a lack of cold gas in galaxies at intermediate redshifts as predicted by cosmological simulations of galaxy formation. This may lay at the root of other problems theoretical models face at the same redshifts.

  20. Predicting the redshift 2 Halpha luminosity function using [OIII] emission line galaxies

    CERN Document Server

    Mehta, Vihang; Colbert, James W; Dai, Sophia; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry; Bagley, Micaela; Beck, Melanie; Ross, Nathaniel R; Rutkowski, Michael; Wang, Yun

    2015-01-01

    Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure Baryonic Acoustic Oscillations (BAOs) in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the WFC3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of Halpha (Ha) emitters observable by these future surveys. WISP is an ongoing HST slitless spectroscopic survey, covering the 0.8-1.65micron wavelength range and allowing the detection of Ha emitters up to z~1.5 and [OIII] emitters to z~2.3. We derive the Ha-[OIII] bivariate line luminosity function for WISP galaxies at z~1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurement, and demonstrate how it can be used to derive the Ha luminosity function from exclusively fitting [OIII] data. Using the z~2 [OIII] line luminosity function, and assuming that the relation betwe...

  1. The Seven Sisters DANCe. I. Empirical isochrones, Luminosity and Mass Functions of the Pleiades cluster

    CERN Document Server

    Bouy, H; Sarro, L M; Barrado, D; Moraux, E; Bouvier, J; Cuillandre, J -C; Berihuete, A; Olivares, J; Beletsky, Y

    2015-01-01

    The DANCe survey provides photometric and astrometric (position and proper motion) measurements for approximately 2 millions unique sources in a region encompassing $\\approx$80deg$^{2}$ centered around the Pleiades cluster. We aim at deriving a complete census of the Pleiades, and measure the mass and luminosity function of the cluster. Using the probabilistic selection method described in Sarro+2014, we identify high probability members in the DANCe ($i\\ge$14mag) and Tycho-2 ($V\\lesssim$12mag) catalogues, and study the properties of the cluster over the corresponding luminosity range. We find a total of 2109 high probability members, of which 812 are new, making it the most extensive and complete census of the cluster to date. The luminosity and mass functions of the cluster are computed from the most massive members down to $\\approx$0.025M$_{\\odot}$. The size, sensitivity and quality of the sample result in the most precise luminosity and mass functions observed to date for a cluster. Our census supersedes ...

  2. AGNs and galaxy interactions

    CERN Document Server

    Alonso, M S; Tissera, P; Coldwell, G; Lambas, Diego G.; Tissera, Patricia; Coldwell, Georgina

    2007-01-01

    We perform a statistical analysis of AGN host characteristics and nuclear activity for AGNs in pairs and without companions. Our study concerns a sample of AGNs derived from the SDSS-DR4 data by Kauffmann et al (2003) and pair galaxies obtained from the same data set by Alonso et al. (2006). An eye-ball classification of images of 1607 close pairs ($r_p<25$ kpc $h^{-1}$, $\\Delta V<350$ km $s^{-1}$) according to the evidence of interaction through distorted morphologies and tidal features provides us with a more confident assessment of galaxy interactions from this sample. We notice that, at a given luminosity or stellar mass content, the fraction of AGNs is larger for pair galaxies exhibiting evidence for strong interaction and tidal features which also show sings of strong star formation activity. Nevertheless, this process accounts only for a $\\sim 10%$ increase of the fraction of AGNs. As in previous works, we find AGN hosts to be redder and with a larger concentration morphological index than non-AG...

  3. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    Science.gov (United States)

    Takeuchi, Tsutomu T.

    2010-08-01

    We provide an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient |ρ| correlation is stronger, the FGM copula cannot work anymore. In this case, we propose using a Gaussian copula, which connects two given marginals and is directly related to the linear correlation coefficient between two variables. Using the copulas, we construct the bivariate luminosity function (BLF) and discuss its statistical properties. We focus especially on the far-infrared-far-ulatraviolet (FUV-FIR) BLF, since these two wavelength regions are related to star-formation (SF) activity. Though both the FUV and FIR are related to SF activity, the univariate LFs have a very different functional form: the former is well described by the Schechter function whilst the latter has a much more extended power-law-like luminous end. We construct the FUV-FIR BLFs using the FGM and Gaussian copulas with different strengths of correlation, and examine their statistical properties. We then discuss some further possible applications of the BLF: the problem of a multiband flux-limited sample selection, the construction of the star-formation rate (SFR) function, and the construction of the stellar mass of galaxies (M*)-specific SFR (SFR/M*) relation. The copulas turn out to be a very useful tool to investigate all these issues, especially for including complicated selection effects.

  4. The Herschel* PEP-HERMES Luminosity Function- I. Probing the Evolution of PACS Selected Galaxies to z approx. equal to 4

    Science.gov (United States)

    Gruppioni, Carlotta; Pozzi, F.; Rodighiero, G.; Delvecchio, I.; Berta, S.; Pozzetti, L.; Zamorani, G.; Andreani, P.; Cimatti, A.; Ilbert, O.; LeFloc'h, E.; Lutz, D.; Magnelli, B.; Marchetti, L.; Monaco, P.; Nordon, R.; Oliver, S.; Popesso, P.; Riguccini, L.; Roseboom, I.; Rosario, D. J.; Sargent, M.; Vaccari, M.; Altieri, B.; Amblard, A.; Bock, J.; Dowell, C. D.; Dwek, E.; Levenson, L.; Lu, N.; Nguyen, H. T.; Schulz, B.; Shupe, D. L.; Xu, C. K.

    2013-01-01

    We exploit the deep and extended far-IR data sets (at 70, 100 and 160 µm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 µm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z 4.We detect very strong luminosity evolution for the total IR LF (LIR ? (1 + z)(sup 3.55 +/- 0.10) up to z 2, and ? (1 + z)(sup 1.62 +/- 0.51) at 2 less than z less than approximately 4) combined with a density evolution (? (1 + z)(sup -0.57 +/- 0.22) up to z 1 and ? (1 + z)(sup -3.92 +/- 0.34) at 1 less than z less than approximately 4). In agreement with previous findings, the IR luminosity density (?IR) increases steeply to z 1, then flattens between z 1 and z 3 to decrease at z greater than approximately 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ?IR. Galaxies occupying the well-established SFR-stellar mass main sequence (MS) are found to dominate both the total IR LF and ?IR at all redshifts, with the contribution from off-MS sources (=0.6 dex above MS) being nearly constant (20 per cent of the total ?IR) and showing no significant signs of increase with increasing z over the whole 0.8 < z <2.2 range. Sources with mass in the range 10 = log(M/solar mass) = 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (greater than approximately 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event

  5. GLOBULAR CLUSTER SYSTEMS IN BRIGHTEST CLUSTER GALAXIES: A NEAR-UNIVERSAL LUMINOSITY FUNCTION?

    Energy Technology Data Exchange (ETDEWEB)

    Harris, William E.; O' Halloran, Heather; Cockcroft, Robert, E-mail: harris@physics.mcmaster.ca, E-mail: ohallohm@mcmaster.ca, E-mail: cockcroft@physics.mcmaster.ca [Department of Physics and Astronomy, McMaster University, Hamilton, ON (Canada); and others

    2014-12-20

    We present the first results from our Hubble Space Telescope brightest cluster galaxy (BCG) survey of seven central supergiant cluster galaxies and their globular cluster (GC) systems. We measure a total of 48,000 GCs in all seven galaxies, representing the largest single GC database. We find that a log-normal shape accurately matches the observed the luminosity function (LF) of the GCs down to the globular cluster luminosity function turnover point, which is near our photometric limit. In addition, the LF has a virtually identical shape in all seven galaxies. Our data underscore the similarity in the formation mechanism of massive star clusters in diverse galactic environments. At the highest luminosities (L ≳ 10{sup 7} L {sub ☉}), we find small numbers of ''superluminous'' objects in five of the galaxies; their luminosity and color ranges are at least partly consistent with those of ultra-compact dwarfs. Last, we find preliminary evidence that in the outer halo (R ≳ 20 kpc), the LF turnover point shows a weak dependence on projected distance, scaling as L {sub 0} ∼ R {sup –0.2}, while the LF dispersion remains nearly constant.

  6. Predicting the Redshift 2 H-Alpha Luminosity Function Using [OIII] Emission Line Galaxies

    Science.gov (United States)

    Mehta, Vihang; Scarlata, Claudia; Colbert, James W.; Dai, Y. S.; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry I.; Bagley, Micaela; Beck, Melanie; Ross, Nathaniel R.; Rutkowski, Michael; Wang, Yun

    2015-01-01

    Upcoming space-based surveys such as Euclid and WFIRST-AFTA plan to measure Baryonic Acoustic Oscillations (BAOs) in order to study dark energy. These surveys will use IR slitless grism spectroscopy to measure redshifts of a large number of galaxies over a significant redshift range. In this paper, we use the WFC3 Infrared Spectroscopic Parallel Survey (WISP) to estimate the expected number of H-alpha emitters observable by these future surveys. WISP is an ongoing Hubble Space Telescope slitless spectroscopic survey, covering the 0.8 - 1.65 micrometers wavelength range and allowing the detection of H-alpha emitters up to z approximately equal to 1.5 and [OIII] emitters to z approximately equal to 2.3. We derive the H-alpha-[OIII] bivariate line luminosity function for WISP galaxies at z approximately equal to 1 using a maximum likelihood estimator that properly accounts for uncertainties in line luminosity measurement, and demonstrate how it can be used to derive the H-alpha luminosity function from exclusively fitting [OIII] data. Using the z approximately equal to 2 [OIII] line luminosity function, and assuming that the relation between H-alpha and [OIII] luminosity does not change significantly over the redshift range, we predict the H-alpha number counts at z approximately equal to 2 - the upper end of the redshift range of interest for the future surveys. For the redshift range 0.7 less than z less than 2, we expect approximately 3000 galaxies per sq deg for a flux limit of 3 x 10(exp -16) ergs per sec per sq cm (the proposed depth of Euclid galaxy redshift survey) and approximately 20,000 galaxies per sq deg for a flux limit of approximately 10(exp -16) ergs per sec per sq cm (the baseline depth of WFIRST galaxy redshift survey).

  7. Measuring the Dark Matter Halo Mass of X-ray AGN at z~1 using photometric redshifts

    OpenAIRE

    Mountrichas, G.; Georgakakis, A.; Finoguenov, A.; Erfanianfar, G.; Cooper, M. C.; Coil, A. L.; Laird, E. S.; Nandra, K.; Newman, J. A.

    2012-01-01

    Data from the AEGIS, COSMOS and ECDFS surveys are combined to infer the bias and dark matter halo mass of moderate luminosity [LX(2-10 keV) = 42.9 erg s-1] X-ray AGN at z~1 via their cross-correlation function with galaxies. In contrast to standard cross-correlation function estimators, we present a method that requires spectroscopy only for the AGN and uses photometric redshift probability distribution functions for galaxies to determine the projected real-space AGN/galaxy cross-correlation ...

  8. Black hole variability and the star formation-AGN connection: Do all star-forming galaxies host an AGN?

    OpenAIRE

    Hickox, R. C.; Mullaney, J. R.; Alexander, D. M.; Chen, C.-T.J.; Civano, F. M.; Goulding, A. D.; Hainline, K. N.

    2013-01-01

    We investigate the effect of active galactic nucleus (AGN) variability on the observed connection between star formation and black hole accretion in extragalactic surveys. Recent studies have reported relatively weak correlations between observed AGN luminosities and the properties of AGN hosts, which has been interpreted to imply that there is no direct connection between AGN activity and star formation. However, AGNs may be expected to vary significantly on a wide range of timescales (from ...

  9. Galaxy And Mass Assembly (GAMA): The galaxy luminosity function within the cosmic web

    CERN Document Server

    Eardley, E; McNaught-Roberts, T; Heymans, C; Norberg, P; Alpaslan, M; Baldry, I; Bland-Hawthorn, J; Brough, S; Cluver, M E; Driver, S P; Farrow, D J; Liske, J; Loveday, J; Robotham, A S G

    2014-01-01

    We investigate the dependence of the galaxy luminosity function on geometric environment within the Galaxy And Mass Assembly (GAMA) survey. The tidal tensor prescription, based on the Hessian of the pseudo-gravitational potential, is used to classify the cosmic web and define the geometric environments: for a given smoothing scale, we classify every position of the surveyed region, $0.04<{z}<0.26$, as either a void, a sheet, a filament or a knot. We consider how to choose appropriate thresholds in the eigenvalues of the Hessian in order to partition the galaxies approximately evenly between environments. We find a significant variation in the luminosity function of galaxies between different geometric environments; the normalisation, characterised by $\\phi^{*}$ in a Schechter function fit, increases by an order of magnitude from voids to knots. The turnover magnitude, characterised by $M^*$, brightens by approximately $0.5$ mag from voids to knots. However, we show that the observed modulation can be en...

  10. The Bright End of the Luminosity Function of Red Sequence Galaxies

    CERN Document Server

    Loh, Y S; Loh, Yeong-Shang; Strauss, Michael A.

    2006-01-01

    We study the bright end of the luminosity distribution of galaxies in fields with Luminous Red Galaxies (LRG) from the Sloan Digital Sky Survey (SDSS). Using 2099 square degree of SDSS imaging data, we search for luminous (> L*) early-type galaxies within 1.0 Mpc/h of a volume-limited sample of 12,608 spectroscopic LRG in the redshift range 0.12 < z < 0.38. Most of these objects lie in rich environments, with the LRG being the brightest object within 1.0 Mpc/h. The luminosity gap, M12, between the first and second-rank galaxies within 1.0 Mpc/h is large (~0.8 mag), substantially larger than can be explained with an exponentially decaying luminosity function of galaxies. The brightest member is less luminous (by 0.1 to 0.2 mag), and shows a larger gap in LRG selected groups than in cluster-like environments. The large luminosity gap shows little evolution with redshift to z = 0.4, ruling out the scenario that these LRG selected brightest cluster or group galaxies grow by recent cannibalism of cluster mem...

  11. The Evolution of the Luminosity Function in Deep Fields A Comparison with CDM Models

    CERN Document Server

    Poli, F; Giallongo, E; Fontana, A; Cristiani, S; D'Odorico, S

    2001-01-01

    The galaxy Luminosity Function (LF) has been estimated in the rest frame B luminosity at 0luminosity of the low luminosity objects. The implications of our resul...

  12. Spectral Energy Distributions of low-luminosity radio galaxies at z~1-3: a high-z view of the host/AGN connection

    CERN Document Server

    Baldi, Ranieri D; Capetti, Alessandro; Rodriguez-Zaurin, Javier; Deustua, Susana; Sparks, William B

    2012-01-01

    We study the Spectral Energy Distributions, SEDs, (from FUV to MIR bands) of the first sizeable sample of 34 low-luminosity radio galaxies at high redshifts, selected in the COSMOS field. To model the SEDs we use two different template-fitting techniques: i) the Hyperz code that only considers single stellar templates and ii) our own developed technique 2SPD that also includes the contribution from a young stellar population and dust emission. The resulting photometric redshifts range from z ~0.7 to 3 and are in substantial agreement with measurements from earlier work, but significantly more accurate. The SED of most objects is consistent with a dominant contribution from an old stellar population with an age ~1 - 3 10^{9} years. The inferred total stellar mass range is ~10^{10} - 10^{12} M(sun). Dust emission is needed to account for the 24micron emission in 15 objects. Estimates of the dust luminosity yield values in the range L_{dust} ~10^{43.5} -10^{45.5} erg s^{-1}. The global dust temperature, crudely ...

  13. Neural network method for galaxy classification: the luminosity function of E/S0 in clusters

    Science.gov (United States)

    Molinari, Emilio; Smareglia, Riccardo

    1998-02-01

    We present a method based on the non-linear behaviour of neural network for the identification of the early-type population in the cores of galaxy clusters. A Kohonen Self Organising Map applied on a three-colour photometric catalogue of objects enabled us to select in each passband the elliptical galaxies. We measured in this way the luminosity function of the E/S0 galaxies selected in this way. Such luminosity functions show peculiarities which disfavour the hypothesis of its universality often claimed for rich clusters and that can be related to the past dynamical history of the cluster as a whole. Based on observations made at the European Southern Observatory (ESO), La Silla, Chile

  14. THE CLUSTER AND FIELD GALAXY ACTIVE GALACTIC NUCLEUS FRACTION AT z = 1-1.5: EVIDENCE FOR A REVERSAL OF THE LOCAL ANTICORRELATION BETWEEN ENVIRONMENT AND AGN FRACTION

    International Nuclear Information System (INIS)

    The fraction of cluster galaxies that host luminous active galactic nuclei (AGNs) is an important probe of AGN fueling processes, the cold interstellar medium at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M ≥ 1014 M☉) at 1 A = 3.0+2.4-1.4% for AGNs with a rest-frame, hard X-ray luminosity greater than LX,H ≥ 1044 erg s–1. This fraction is measured relative to all cluster galaxies more luminous than M*3.6(z) + 1, where M*3.6(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6 μm bandpass. The cluster AGN fraction is 30 times greater than the 3σ upper limit on the value for AGNs of similar luminosity at z ∼ 0.25, as well as more than an order of magnitude greater than the AGN fraction at z ∼ 0.75. AGNs with LX,H ≥ 1043 erg s–1 exhibit similarly pronounced evolution with redshift. In contrast to the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1 < z < 1.5. This is evidence that the cluster AGN population has evolved more rapidly than the field population from z ∼ 1.5 to the present. This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field.

  15. Radial Density Statistics of the Galaxy Distribution and the Luminosity Function

    CERN Document Server

    Iribarrem, Alvaro S; Stoeger, William R

    2012-01-01

    This paper discusses a connection between the relativistic number counts of cosmological sources and the observed galaxy luminosity function (LF). Observational differential number densities are defined and obtained from published LF data using such connection. We observe a distortion in the observational quantities that increases with higher redshift values as compared to the theoretical predictions. The use of different cosmological distance measures plays a role in such a distortion

  16. The European Large Area ISO Survey - IV. The preliminary 90-mu m luminosity function

    DEFF Research Database (Denmark)

    Serjeant, S.; Efstathiou, A.; Oliver, S.;

    2001-01-01

    from the Efstathiou et al. S-90 100 mJy data base, we have found optical, 15-mum or 1.4-GHz identifications for 24 (65 per cent). We have obtained 2dF and UK Schmidt FLAIR spectroscopy of 89 per cent of identifications to rigid multivariate flux limits. We construct a luminosity function assuming that...... broad agreement with the Flores et al. and Rowan-Robinson et al. mid-infrared-based estimates....

  17. The luminosity function of galactic ultra-compact HII regions and the IMF for massive stars

    CERN Document Server

    Casassus, S; May, J; Nyman, L A A

    2000-01-01

    The population of newly formed massive stars, while still embedded in their parent molecular clouds, is studied on the galactic disk scale. We analyse the luminosity function of IRAS point-like sources, with far-infrared (FIR) colours of ultra-compact HII regions, that have been detected in the CS(2-1) line - a tracer of high density molecular gas. The FIR luminosities of 555 massive star forming regions (MSFRs), 413 of which lie within the solar circle, are inferred from their fluxes in the four IRAS bands and from their kinematic distances, derived using the CS(2-1) velocity profiles. The luminosity function (LF) for the UCHII region candidates shows a peak well above the completeness limit, and is different within and outside the solar circle (96% confidence level). While within the solar circle the LF has a maximum for 2E5 Lo, outside the solar circle the maximum is at 5E4 Lo. We model the LF using three free parameters: -alpha, the exponent for the initial mass function (IMF) expressed in log(M/Mo); -bet...

  18. Constraining the rate and luminosity function of Swift gamma-ray bursts

    CERN Document Server

    Howell, E J; Stratta, G; Gendre, B; Zhou, H

    2014-01-01

    We compute the intrinsic isotropic peak luminosity function (LF) and formation rate of long gamma-ray bursts (LGRBs) using a novel approach. We complement a standard log\\,$N$\\,--\\,log\\,$P$ brightness distribution and $V_{\\mathrm{max}}$ estimations with two observation-time relations: a redshift--observation-time relation (log\\,$z$\\,--\\,log\\,$T$) and a new luminosity--observation-time relation (log\\,$L$\\,--\\,log\\,$T$). We show that this approach reduces degeneracies that exist between the rate and LF of a brightness distribution. To account for the complex triggering algorithm employed by \\emph{Swift} we use recent results of \\citet{Lien_2014ApJ} to produce a suite of efficiency functions. Using these functions with the above methods, we show that a log\\,$L$\\,--\\,log\\,$T$ method can provide good constraints on the form of the LF, particularly the high end. Using a sample of 175 peak luminosities determined from redshifts with well defined selection criteria our results suggest that LGRBs occur at a local rate ...

  19. How are AGN Found?

    CERN Document Server

    Mushotzky, R

    2004-01-01

    We discuss the very different methods in each wavelength band for selecting and finding Active Galactic Nuclei (AGN). We briefly review the history of the different techniques for finding AGN and compare and contrast the advantages and difficulties of selection in different wavelength bands. We stress the strong selection effects in each wavelength band and the difficulty of defining complete samples. Of all the techniques presently used, we conclude that selection in the hard X-ray band via imaging and spectroscopy is the most complete and allows the best estimate of the number and evolution of active galaxies. However, all of the techniques have difficulties at low luminosities where emission due to stellar processes can have similar sizes and luminosities.

  20. A near infrared test for two recent luminosity functions for galaxies

    CERN Document Server

    Zaninetti, L

    2014-01-01

    Two recent luminosity function (LF) for galaxies are reviewed and the parameters which characterize the near infrared are fixed. A first LF is a modified Schechter LF with four parameters. The second LF is derived from the generalized gamma and has four parameters. The formulas which give the number of galaxies as function of the redshift are reviewed and a special attention is given to the position of the photometric maximum which is expressed as function of a critical parameter or the flux of radiation or the apparent magnitude. A simulation of the 2MASS Redshift Survey is given in the framework of the non Poissonian Voronoi Tessellation.

  1. Toward a Unified AGN Structure

    Science.gov (United States)

    Kazanas, Demosthenes; Fukumura, Keigo; Shrader, Chris; Behar, Ehud; Contopoulosa, Ioannis

    2012-01-01

    We present a unified model for the structure and appearance of accretion powered sources across their entire luminosity range from galactic X-ray binaries (XRB) to luminous quasars, with emphasis on AG N and their phenomenology. Central to this model is the notion of MHD winds launched by the accretion disks that power these objects. These winds provide the matter that manifests as blueshifted absorption features in the UV and X-ray spectra of a large fraction of these sources; furthermore, their density distribution in the poloidal plane determines their "appearance" (i.e. the column and velocity structure of these absorption features and the obscuration of the continuum source) as a function of the observer inclination angle (a feature to which INTEGRAL has made significant contributions). This work focuses on just the broadest characteristics of these objects; nonetheless, it provides scaling laws that allow one to reproduce within this model the properties of objects extending in luminosity from luminous quasars to XRBs. Our general conclusion is that the AGN phenomenology can be accounted for in terms of three parameters: The wind maSS flux in units of the Eddington value, m(dot), the observers' inclination angle Theta and the logarithmic slope between the 0/UV and X-ray fluxes alpha(sub ox); however because of a correlation between alpha(sub ox) and UV luminosity the number of significant parameters is two. The AGN correlations implied by this model appear to extend to and consistent with the XRB phenomenology, suggesting the presence of a truly unified underlying structure for accretion powered sources.

  2. THE GALACTIC SPIN OF AGN GALAXIES

    International Nuclear Information System (INIS)

    Using an extensive sample of galaxies selected from the Sloan Digital Sky Survey Data Release 5, we compare the angular momentum distribution of active galactic nuclei (AGNs) with non-AGN hosting late-type galaxies. To this end we characterize galactic spin through the dimensionless angular momentum parameter λ, which we estimate through simple dynamical considerations. Using a volume-limited sample, we find a considerable difference when comparing the empirical distributions of λ for AGNs and non-AGN galaxies, the AGNs showing typically low λ values and associated dispersions, while non-AGNs present higher λ values and a broader distribution. A more striking difference is found when looking at λ distributions in thin Mr cuts; while the spin of non-AGN galaxies presents an anticorrelation with Mr , with bright (massive) galaxies having low spins, AGN host galaxies present uniform values of λ at all magnitudes, a behavior probably imposed by the fact that most late-type AGN galaxies present a narrow range in color, with a typical constant λ value. We also find that the fraction of AGN hosting galaxies in our sample strongly depends on galactic spin, increasing dramatically for decreasing λ. For AGN host galaxies, we compute the mass of their supermassive black holes and find that this value tends to be higher for low spin galaxies, even at fixed luminosity, a result that could account, to a certain extent, for the spread on the luminosity-black-hole mass relation.

  3. The Seven Sisters DANCe. I. Empirical isochrones, luminosity, and mass functions of the Pleiades cluster

    Science.gov (United States)

    Bouy, H.; Bertin, E.; Sarro, L. M.; Barrado, D.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Berihuete, A.; Olivares, J.; Beletsky, Y.

    2015-05-01

    Context. The DANCe survey provides photometric and astrometric (position and proper motion) measurements for approximately 2 million unique sources in a region encompassing ~80 deg2 centered on the Pleiades cluster. Aims: We aim at deriving a complete census of the Pleiades and measure the mass and luminosity functions of the cluster. Methods: Using the probabilistic selection method previously described, we identified high probability members in the DANCe (i ≥ 14 mag) and Tycho-2 (V ≲ 12 mag) catalogues and studied the properties of the cluster over the corresponding luminosity range. Results: We find a total of 2109 high-probability members, of which 812 are new, making it the most extensive and complete census of the cluster to date. The luminosity and mass functions of the cluster are computed from the most massive members down to ~0.025 M⊙. The size, sensitivity, and quality of the sample result in the most precise luminosity and mass functions observed to date for a cluster. Conclusions: Our census supersedes previous studies of the Pleiades cluster populations, in terms of both sensitivity and accuracy. Based on service observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Table 1 and Appendices are available in electronic form at http://www.aanda.orgDANCe catalogs (Tables 6 and 7) and full Tables 2-5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A148

  4. A search for X-ray reprocessing echoes in the power spectral density functions of AGN

    Science.gov (United States)

    Emmanoulopoulos, D.; Papadakis, I. E.; Epitropakis, A.; Pecháček, T.; Dovčiak, M.; McHardy, I. M.

    2016-09-01

    We present the results of a detailed study of the X-ray power spectral density (PSD) functions of 12 X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection occurs in the inner part of the accretion disc of AGN, the X-ray reflection component should be a filtered echo of the X-ray continuum signal and should be equal to the convolution of the primary emission with the response function of the disc. Our primary objective is to search for these reflection features in the 5-7 keV (iron line) and 0.5-1 keV (soft) bands, where the X-ray reflection fraction is expected to be dominant. We fit to the observed periodograms two models: a simple bending power-law model (BPL) and a BPL model convolved with the transfer function of the accretion disc assuming the lamp-post geometry and X-ray reflection from a homogeneous disc. We do not find any significant features in the best-fitting BPL model residuals either in individual PSDs in the iron band, soft and full band (0.3-10 keV) or in the average PSD residuals of the brightest and more variable sources (with similar black hole mass estimates). The typical amplitude of the soft and full-band residuals is around 3-5 per cent. It is possible that the expected general relativistic effects are not detected because they are intrinsically lower than the uncertainty of the current PSDs, even in the strong relativistic case in which X-ray reflection occurs on a disc around a fast rotating black hole having an X-ray source very close above it. However, we could place strong constrains to the X-ray reflection geometry with the current data sets if we knew in advance the intrinsic shape of the X-ray PSDs, particularly its high-frequency slope.

  5. A search for X-ray reprocessing echoes in the power spectral density functions of AGN

    Science.gov (United States)

    Emmanoulopoulos, D.; Papadakis, I. E.; Epitropakis, A.; Pecháček, T.; Dovčiak, M.; McHardy, I. M.

    2016-06-01

    We present the results of a detailed study of the X-ray power spectra density (PSD) functions of twelve X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection occurs in the inner part of the accretion disc of AGN, the X-ray reflection component should be a filtered echo of the X-ray continuum signal and should be equal to the convolution of the primary emission with the response function of the disc. Our primary objective is to search for these reflection features in the 5 - 7 keV (iron line) and 0.5 - 1 keV (soft) bands, where the X-ray reflection fraction is expected to be dominant. We fit to the observed periodograms two models: a simple bending power law model (BPL) and a BPL model convolved with the transfer function of the accretion disc assuming the lamp-post geometry and X-ray reflection from a homogeneous disc. We do not find any significant features in the best-fitting BPL model residuals either in individual PSDs in the iron band, soft and full band (0.3 - 10 keV) or in the average PSD residuals of the brightest and more variable sources (with similar black hole mass estimates). The typical amplitude of the soft and full-band residuals is around 3 - 5 per cent. It is possible that the expected general relativistic effects are not detected because they are intrinsically lower than the uncertainty of the current PSDs, even in the strong relativistic case in which X-ray reflection occurs on a disc around a fast rotating black hole having an X-ray source very close above it. However, we could place strong constrains to the X-ray reflection geometry with the current data sets if we knew in advance the intrinsic shape of the X-ray PSDs, particularly its high frequency slope.

  6. Hard X-ray Variability of AGN

    CERN Document Server

    Beckmann, V; Courvoisier, T J -L; Gehrels, N; Soldi, S; Tüller, J; Wendt, G

    2007-01-01

    Aims: Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods: The first 9 months of the Swift/BAT all-sky survey are used to study the 14 - 195 keV variability of the 44 brightest AGN. The sources have been selected due to their detection significance of >10 sigma. We tested the variability using a maximum likelihood estimator and by analysing the structure function. Results: Probing different time scales, it appears that the absorbed AGN are more variable than the unabsorbed ones. The same applies for the comparison of Seyfert 2 and Seyfert 1 objects. As expected the blazars show stronger variability. 15% of the non-blazar AGN show variability of >20% compared to the average flux on time scales of 20 days, and 30% show at least 10% flux variation. All the non-blazar AGN which show strong variability are low-luminosity objects with L(14-195 keV) < 1E44 erg/sec. Conclusions: Concer...

  7. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    International Nuclear Information System (INIS)

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lépine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Å) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5σ) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ∼16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law

  8. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    Energy Technology Data Exchange (ETDEWEB)

    Ansdell, Megan; Baranec, Christoph [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822 (United States); Mann, Andrew W. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Lépine, Sebastien [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302 (United States); James, David [Cerro Tololo Inter-American Observatory, Casilla 603 La Serena (Chile); Buccino, Andrea; Mauas, Pablo; Petrucci, Romina [Instituto de Astronomía y Física del Espacio, C1428EHA Buenos Aires (Argentina); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Riddle, Reed [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-01-01

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lépine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Å) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5σ) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ∼16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.

  9. The Impact of Dust in Host Galaxies on Quasar Luminosity Functions

    CERN Document Server

    Shirakata, H; Enoki, M; Nagashima, M; Kobayashi, M A R; Ishiyama, T; Makiya, R

    2014-01-01

    We have investigated effects of dust attenuation on quasar luminosity functions using a semi-analytic galaxy formation model combined with a large cosmological N-body simulation. We estimate the dust attenuation of quasars self-consistently with that of galaxies by considering the dust in their host bulges.We find that the luminosity of the bright quasars is strongly dimmed by the dust attenuation, about 2 mag in the B-band, and that the faint end slope of the luminosity function is steepened. We also study for the first time the case in which gas fueling to a central black hole starts some time after the beginning of the starburst induced by a major merger. In this case, nuclei are less attenuated by the dust since the cold gas in the bulges is consumed by the starbursts and expelled by the stellar feedback. In order to make the dust attenuation of the quasars negligible, the accretion has to be delayed at least five times the dynamical timescale of their host bulges.

  10. Measuring the Dark Matter Halo Mass of X-ray AGN at z~1 using photometric redshifts

    CERN Document Server

    Mountrichas, G; Finoguenov, A; Erfanianfar, G; Cooper, M C; Coil, A L; Laird, E S; Nandra, K; Newman, J A

    2012-01-01

    Data from the AEGIS, COSMOS and ECDFS surveys are combined to infer the bias and dark matter halo mass of moderate luminosity [LX(2-10 keV) = 42.9 erg s-1] X-ray AGN at z~1 via their cross-correlation function with galaxies. In contrast to standard cross-correlation function estimators, we present a method that requires spectroscopy only for the AGN and uses photometric redshift probability distribution functions for galaxies to determine the projected real-space AGN/galaxy cross-correlation function. The estimated dark matter halo mass of X-ray AGN in the combined AEGIS, COSMOS and ECDFS fields is ~13h-1M_solar, in agreement with previous studies at similar redshift and luminosity ranges. Removing from the sample the 5 per cent of the AGN associated with X-ray selected groups results in a reduction by about 0.5 dex in the inferred AGN dark matter halo mass. The distribution of AGN in dark matter halo mass is therefore skewed and the bulk of the population lives in moderate mass haloes. This result favour col...

  11. Modeling the Redshift Evolution of the Normal Galaxy X-Ray Luminosity Function

    Science.gov (United States)

    Tremmel, M.; Fragos, T.; Lehmer, B. D.; Tzanavaris, P.; Belczynski, K.; Kalogera, V.; Basu-Zych, A. R.; Farr, W. M.; Hornschemeier, A.; Jenkins, L.; Ptak, A.; Zezas, A.

    2013-01-01

    Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high-redshift galaxies allow us to probe the formation and evolution of XRBs on very long timescales (approximately 10 Gyr). In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z = 0 to approximately 20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy. We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low common envelope efficiencies, a 50% twins mass ratio distribution, a steeper initial mass function exponent, and high stellar wind mass-loss rates best match observational results from Tzanavaris & Georgantopoulos, though they significantly underproduce bright early-type and very bright (L(sub x) greater than 10(exp 41)) late-type galaxies. These discrepancies are likely caused by uncertainties in hot gas emission and SFHs, active galactic nucleus contamination, and a lack of dynamically formed low-mass XRBs. In our highest likelihood models, we find that hot gas emission dominates the emission for most bright galaxies. We also find that the evolution of the normal galaxy X-ray luminosity density out to z = 4 is driven largely by XRBs in galaxies with X-ray luminosities between 10(exp 40) and 10(exp 41) erg s(exp -1).

  12. A low-redshift low luminosity QSO sample: Comparison with NUGA galaxies and PG QSOs and first interferometric images of three sample members

    CERN Document Server

    Moser, Lydia; Fischer, Sebastian; Busch, Gerold; Valencia-S., Monica; Eckart, Andreas; Krips, Melanie; Scharwaechter, Julia

    2013-01-01

    The low luminosity QSO (LLQSO) sample consists of type 1 active galactic nuclei (AGN) up to a redshift of z=0.06 in the Hamburg/ESO QSO survey. Its purpose is to study how the brightest AGN in the nearby universe evolve with respect to AGN activity and host properties as a function of redshift. We show that our sample lies well between the NUclei of GAlaxies (NUGA) sample and the Palomar Green (PG) QSO sample in terms of redshift, gas masses and luminosities and seems to connect them. The continuous growth in mass, luminosity and, linked to this, the AGN activity over the samples has either a statistical reason or is indicative of an evolutionary link between the different populations and might be related to cosmic downsizing. In addition, we present first results of our observations of three galaxies from our sample with the Submillimeter Array (SMA).

  13. The Optical Luminosity Function of Void Galaxies in the SDSS and ALFALFA Surveys

    Science.gov (United States)

    Moorman, Crystal M.; Vogeley, Michael S.; Hoyle, Fiona; Pan, Danny C.; Haynes, Martha P.; Giovanelli, Riccardo

    2015-09-01

    We measure the r-band galaxy luminosity function (LF) across environments over the redshift range 0 ALFALFA). We find that the global LF of the ALFALFA sample is not well fit by a Schechter function because of the presence of a wide dip in the LF around Mr = -18 and an upturn at fainter magnitudes (α ˜ -1.47). We compare the H i selected r-band LF to various LFs of optically selected populations to determine where the H i selected optical LF obtains its shape. We find that sample selection plays a large role in determining the shape of the LF.

  14. The rest-frame optical luminosity functions of galaxies at 2

    CERN Document Server

    Marchesini, D; Quadri, R; Rudnick, G; Franx, M; Lira, P; Wuyts, S; Gawiser, E; Christlein, D; Toft, S; Marchesini, Danilo; Dokkum, Pieter van; Quadri, Ryan; Rudnick, Gregory; Franx, Marijn; Lira, Paulina; Wuyts, Stijn; Gawiser, Eric; Christlein, Daniel; Toft, Sune

    2006-01-01

    [ABRIDGED] We present the rest-frame optical (B, V, and R-band) luminosity functions (LFs) of galaxies at 22 are consistent with those in the local LFs. The characteristic magnitudes are significantly brighter than the local values, while the measured values for Phi_star are a factor of ~5 smaller with respect to the local values. By integrating the LFs, we estimate the number and luminosity densities. We present for the first time the LF of Distant Red Galaxies (DRGs; defined here as z>2 sources with observed J-K>2.3). While DRGs and non-DRGs are characterized by similar LFs at the bright end, the faint-end slope of the non-DRG LF is much steeper than that of DRGs. Comparing the rest-frame V-band LF of non-DRGs to that inferred for Lyman break galaxies by Shapley et al. (2001), we find a significantly less steep faint-end slope. The contribution of DRGs to the global densities is 14%-25% in number and 22%-33% in luminosity. From the rest-frame U-V colors and stellar population synthesis models, we estimate t...

  15. Globular Cluster Systems in Brightest Cluster Galaxies: A Near-Universal Luminosity Function?

    CERN Document Server

    Harris, William E; Gnedin, Oleg Y; O'Halloran, Heather; Blakeslee, John P; Whitmore, Bradley C; Cote, Patrick; Geisler, Douglas; Peng, Eric W; Bailin, Jeremy; Rothberg, Barry; Cockcroft, Robert; DeGraaff, Regina Barber

    2014-01-01

    We present the first results from our HST Brightest Cluster Galaxy (BCG) survey of seven central supergiant cluster galaxies and their globular cluster (GC) systems. We measure a total of 48000 GCs in all seven galaxies, representing the largest single GC database. We find that a log-normal shape accurately matches the observed luminosity function (LF) of the GCs down to the GCLF turnover point, which is near our photometric limit. In addition, the LF has a virtually identical shape in all seven galaxies. Our data underscore the similarity in the formation mechanism of massive star clusters in diverse galactic environments. At the highest luminosities (log L > 10^7 L_Sun) we find small numbers of "superluminous" objects in five of the galaxies; their luminosity and color ranges are at least partly consistent with those of UCDs (Ultra-Compact Dwarfs). Lastly, we find preliminary evidence that in the outer halo (R > 20 kpc), the LF turnover point shows a weak dependence on projected distance, scaling as L_0 ~ R...

  16. AGN clustering in the local Universe: an unbiased picture from Swift-BAT

    CERN Document Server

    Cappelluti, N; Burlon, D; Krumpe, M; Miyaji, T; Bonoli, S; Greiner, J

    2010-01-01

    We present the clustering measurement of hard X-ray selected AGN in the local Universe. We used a sample of 199 sources spectroscopically confirmed detected by Swift-BAT in its 15-55 keV all-sky survey. We measured the real space projected auto-correlation function and detected a signal significant on projected scales lower than 200 Mpc/h. We measured a correlation length of r0=5.56+0.49-0.43 Mpc/h and a slope {\\gamma}=1.64-0.08 -0.07. We also measured the auto-correlation function of Type I and Type II AGN and found higher correlation length for Type I AGN. We have a marginal evidence of luminosity dependent clustering of AGN, as we detected a larger correlation length of luminous AGN than that of low luminosity sources. The corresponding typical host DM halo masses of Swift-BAT are log(MDMH) 12-14 h^-1 M/M_sun, depending on the subsample. For the whole sample we measured log(MDMH)\\sim 13.15 h-1 M/M_sun which is the typical mass of a galaxy group. We estimated that the local AGN population has a typical life...

  17. Hard X-ray Luminosity Function of Tidal Disruption Events: First Results from MAXI Extragalactic Survey

    CERN Document Server

    Kawamuro, Taiki; Shidatsu, Megumi; Hori, Takafumi; Kawai, Nobuyuki; Negoro, Hitoshi; Mihara, Tatehiro

    2016-01-01

    We derive the first hard X-ray luminosity function (XLF) of stellar tidal disruption events (TDEs) by supermassive black holes (SMBHs), which gives an occurrence rate of TDEs per unit volume as a function of peak luminosity and redshift, utilizing an unbiased sample observed by the Monitor of All-sky X-ray Image (MAXI). On the basis of the light curves characterized by a power-law decay with an index of $-5/3$, a systematic search using the MAXI data in the first 37 months detected four TDEs, all of which have been found in the literature. To formulate the TDE XLF, we consider the mass function of SMBHs, that of disrupted stars, the specific TDE rate as a function of SMBH mass, and the fraction of TDEs with relativistic jets. We perform an unbinned maximum likelihood fit to the MAXI TDE list and check the consistency with the observed TDE rate in the ROSAT all sky survey. The results suggest that the intrinsic fraction of the jet-accompanying events is $0.0007$--$34\\%$. We confirm that at $z \\lesssim 1.5$ the...

  18. BVI Photometry and the Red Giant Branch Luminosity Function of M15

    CERN Document Server

    Feuillet, Diane K; Chaboyer, Brian

    2014-01-01

    We present new $BVI$ photometry containing 40,000 stars of the Galactic globular cluster M15 (NGC 7078) covering a $25 \\times 25$ arcminute area centered on the cluster with a magnitude range from the tip of the Red Giant Branch to three magnitudes below the main sequence turn-off. Using $\\alpha$-enhanced Dartmouth Stellar Evolution Program models, we find an age of $13.0 \\ \\pm \\ 1.0$ Gyr and distance modulus of $(m-M)_V = 15.4 \\pm 0.1$ through isochrone fitting. Unlike previous works, we find good agreement between the observed completeness-corrected stellar luminosity function and models.

  19. First results from HerMES on the evolution of the submillimetre luminosity function

    CERN Document Server

    Eales, S; Roseboom, I G; Altieri, B; Amblard, A; Arumugam, V; Auld, R; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Brisbin, D; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Dye, S; Elbaz, D; Farrah, D; Fox, M; Franceschini, A; Gear, W; Glenn, J; Gonzalez~Solares, E A; Griffin, M; Harwit, M; Hatziminaoglou, E; Huang, J; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lonsdale, C J; Lu, N; Madden, S; Maffei, B; Mainetti, G; Marchetti, L; Morrison, G E; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Owen, F N; Page, M J; Pannella, M; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rawlings, J I; Rigopoulou, D; Rizzo, D; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Strazzullo, V; Symeonidis, M; Trichas, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, K; Zemcov, M

    2010-01-01

    We have carried out two extremely deep surveys with SPIRE, one of the two cameras on Herschel, at 250 microns, close to the peak of the far-infrared background. We have used the results to investigate the evolution of the rest-frame 250-micron luminosity function out to z=2. We find evidence for strong evolution out to a redshift of around 1 but evidence for at most weak evolution beyond this redshift. Our results suggest that a significant part of the stars and metals in the Universe today were formed at z<1.4 in spiral galaxies.

  20. First results from HerMES on the evolution of the submillimetre luminosity function

    OpenAIRE

    Eales, S.; Raymond, G; Roseboom, I. G.; Altieri, B.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Babbedge, T.; Blain, A.; Bock, J.; Boselli, A.; Brisbin, D.; Buat, V.; Burgarella, D.

    2010-01-01

    We have carried out two extremely deep surveys with SPIRE, one of the two cameras on Herschel, at 250 microns, close to the peak of the far-infrared background. We have used the results to investigate the evolution of the rest-frame 250-micron luminosity function out to z=2. We find evidence for strong evolution out to a redshift of around 1 but evidence for at most weak evolution beyond this redshift. Our results suggest that a significant part of the stars and metals in the Universe today w...

  1. The mass of the galactic halo derived from the luminosity function high-velocity stars

    International Nuclear Information System (INIS)

    The local luminosity function of high-velocity stars is derived on the basis of a complete sample of stars of large proper motion with trigonometric parallaxes. The fraction of these stars belonging to a roughly spherical galactic halo is deduced by using a kinematical criterion based on space velocities of metal-poor RR Lyrae variables. The local mass density of halo stars is about 1.7times10-4 solar masses per cubic parsec, corresponding to a fractional mass within the Sun's distance from the center of 6 percent, i.e., an order of magnitude lower than that of the massive halo proposed by Ostriker and Peebles

  2. The distance of the Fornax Cluster based on Globular Cluster Luminosity Functions

    OpenAIRE

    Kohle, Sven; Kissler-Patig, Markus; Hilker, Michael; Richtler, Tom; Infante, L.; Quintana, H.

    1996-01-01

    We present Globular Cluster Luminosity Functions for four ellipticals and one S0-Galaxy in the Fornax cluster of galaxies, derived from CCD photometry in V and I. The averaged turnover magnitudes are $V_{TO} = 23.80 \\pm 0.06$ and $I_{TO} =22.39 \\pm 0.05$, respectively. We derive a relative distance modulus $(m-M)_{Fornax} - (m-M)_{M87} = 0.08 \\pm 0.09$ mag using the turnover of M87 based on HST data.

  3. The dependence of the Lyman_a luminosity function on Redshift using SHARDS

    OpenAIRE

    Rodríguez-Espinosa, J. M.; González-Martín, O.; Aguerri, J. A. L.; Muñoz-Tuñón, C.; Pérez-González, P. G.; Cava, A

    2012-01-01

    We report in this work on a project aimed at determining Ly{\\alpha} luminosity functions from z=3 to z=6. The project is based on the use of very deep photometry from the SHARDS Survey, in a set of 24 medium band filters in the GOODS-N field. We present here some preliminary work carried out with four test images in four consecutive bands. We use the narrow band selection technique for searching emission line candidates. Eleven candidates have been detected so far, many of which are strong Ly...

  4. The K20 survey. V The evolution of the near-IR Luminosity Function

    CERN Document Server

    Pozzetti, L; Zamorani, G; Daddi, E; Menci, N; Fontana, A; Renzini, A; Mignoli, M; Poli, F; Saracco, P; Broadhurst, T J; Cristiani, S; D'Odorico, S; Giallongo, E; Gilmozzi, R

    2003-01-01

    We present the galaxy rest-frame near-IR Luminosity Function (LF) and its cosmic evolution to z=1.5 based on a spectroscopic survey of a magnitude limited sample of galaxies with Ks=1, whereas PLE models are more consistent with the data up to z=1.5. The GIF model (Kaufmann et al. 1999) shows a clear deficiency of red luminous galaxies at z=1 compared to our observations and predicts a decrease of luminous galaxies with redshift not observed in our sample.

  5. The luminosity function of galaxies in elliptical-dominated galaxy groups: clues on the nature of fossil groups

    OpenAIRE

    de Oliveira, Raimundo Lopes; de Oliveira, Claudia Mendes; Dupke, Renato; Sodré, Laerte; Cypriano, Eduardo

    2009-01-01

    We have started a study of luminosity functions of Fossil Group candidates in order to characterize the faint-end of their galaxy distribution. Here we report on results of nine of them from SDSS photometry.

  6. The NuSTAR Extragalactic Surveys: First Direct Measurements of the >10 keV X-Ray Luminosity Function for Active Galactic Nuclei at z>0.1

    CERN Document Server

    Aird, J; Ballantyne, D R; Civano, F; Del-Moro, A; Hickox, R C; Lansbury, G B; Mullaney, J R; Bauer, F E; Brandt, W N; Comastri, A; Fabian, A C; Gandhi, P; Harrison, F A; Luo, B; Stern, D; Treister, E; Zappacosta, L; Ajello, M; Assef, R; Boggs, S E; Brightman, M; Christensen, F E; Craig, W W; Elvis, M; Forster, K; Balokovic, M; Grefenstette, B W; Hailey, C J; Koss, M; LaMassa, S M; Madsen, K K; Puccetti, S; Saez, C; Urry, C M; Wik, D R; Zhang, W

    2015-01-01

    We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of Active Galactic Nuclei (AGNs) based on a sample of 94 sources at 0.1 < z <3, selected at 8-24 keV energies from sources in the NuSTAR extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of the XLF. Adopting a model with a lower intrinsic fraction of Compton-thick sources and a larger population of sources with column densities N_H ~ 10^{23-24} /cm2 or a model with stronger Compton reflection component (with a relative normalization of R ~ 2 at all luminosities) can bring extrapolations of the XLF from 2-10 keV into agreement with our N...

  7. The SDSS Quasar Survey: Quasar Luminosity Function from Data Release Three

    CERN Document Server

    Richards, G T; Barentine, J C; Brewington, H J; Brinkmann, J; Brunner, R J; Fukugita, M; Gray, J; Gunn, J E; Hall, P B; Harvanek, M; Ivezic, Z; Jester, S; Kent, S M; Kirkland, M E; Kleinman, S J; Knapp, G R; Krzesínski, J; Long, D C; Loveday, J; Lupton, R H; Meiksin, A; Nash, T; Neilsen, E H; Nitta, A; Pope, A; Schlegel, D J; Schneider, D P; Snedden, S A; Stoughton, C; Strauss, M A; Szalay, A S; Thakar, A R; Vanden Berk, Daniel E; Xiaohui F; Yanny, B; York, Do G; Anderson, Scott F.; Berk, Daniel E. Vanden; Brunner, Robert J.; Fan, Xiaohui; Gray, Jim; Gunn, James E.; Hall, Patrick B.; Ivezic, Zeljko; Jester, Sebastian; Kirkland, Margaret E.; Loveday, Jon; Meiksin, Avery; Pope, Adrian; Richards, Gordon T.; Schneider, Donald P.; Stoughton, Chris; Strauss, Michael A.; Szalay, Alexander S.; Thakar, Anirudda R.; Yanny, Brian; York, Donald G.

    2006-01-01

    We determine the number counts and z=0-5 luminosity function for a well-defined, homogeneous sample of quasars from the Sloan Digital Sky Survey (SDSS). We conservatively define the most uniform statistical sample possible, consisting of 15,343 quasars within an effective area of 1622 deg^2 that was derived from a parent sample of 46,420 spectroscopically confirmed broad-line quasars in the 5282 deg^2 of imaging data from SDSS Data Release Three. The sample extends from i=15 to i=19.1 at z3. The number counts and luminosity function agree well with the results of the 2dF QSO Survey, but the SDSS data probe to much higher redshifts than does the 2dF sample. The number density of luminous quasars peaks between redshifts 2 and 3, although uncertainties in the selection function in this range do not allow us to determine the peak redshift more precisely. Our best fit model has a flatter bright end slope at high redshift than at low redshift. For z5-sigma level, must be accounted for in models of the evolution of ...

  8. Far-IR/Submillimeter Spectroscopic Cosmological Surveys: Predictions of Infrared Line Luminosity Functions for z<4 Galaxies

    CERN Document Server

    Spinoglio, Luigi; Franceschini, Alberto; Gruppioni, Carlotta; Valiante, Elisabetta; Isaak, Kate

    2011-01-01

    Star formation and accretion onto supermassive black holes in the nuclei of galaxies are the two most energetic processes in the Universe, producing the bulk of the observed emission throughout its history. We simulated the luminosity functions of star-forming and active galaxies for spectral lines that are thought to be good spectroscopic tracers of either phenomenon, as a function of redshift. We focused on the infrared (IR) and sub-millimeter domains, where the effects of dust obscuration are minimal. Using three different and independent theoretical models for galaxy formation and evolution, constrained by multi-wavelength luminosity functions, we computed the number of star-forming and active galaxies per IR luminosity and redshift bin. We converted the continuum luminosity counts into spectral line counts using relationships that we calibrated on mid- and far-IR spectroscopic surveys of galaxies in the local universe. Our results demonstrate that future facilities optimized for survey-mode observations,...

  9. Feedback in AGN heating of galaxy clusters

    OpenAIRE

    Hoeft, M.; Brueggen, M

    2004-01-01

    One of the challenges that models of AGN heating of the intracluster medium (ICM) face, is the question how the mechanical luminosity of the AGN is tuned to the radiative losses of the ICM. Here we implement a simple 1D model of a feedback mechanism that links the luminosity of the AGN to the accretion rate. We demonstrate how this simple feedback mechanism leads to a quasi-steady state for a broad range of parameters. Moreover, within this feedback model, we investigate the effect of thermal...

  10. The IRAS bright galaxy sample. II - The sample and luminosity function

    Science.gov (United States)

    Soifer, B. T.; Sanders, D. B.; Neugebauer, G.; Madore, B. F.; Danielson, G. E.

    1987-01-01

    A statistically complete sample of 324 of the brightest infrared galaxies discovered at 60 microns in the IRAS all-sky survey is described. The results show that far-infrared emission is a significant luminosity component in the local universe, representing 25 percent of the luminosity emitted by stars in the same volume. Above 10 to the 11th solar luminosities, the infrared luminous galaxies are the dominant population of objects in the universe, being as numerous as the Seyfert galaxies and more numerous than quasars at higher luminosities. The infrared luminosity appears to be independent of the optical luminosity of galaxies. Most infrared bright galaxies appear to require much of the interstellar matter to be contributing to the observed infrared luminosity. Approximately 60-80 percent of the far-infrared luminosity of the local universe can be attributed, directly or indirectly, to recent or ongoing star formation.

  11. A Monte Carlo Approach to Evolution of the Far-Infrared Luminosity Function with BLAST

    CERN Document Server

    Marsden, Gaelen; Halpern, Mark; Patanchon, Guillaume; Scott, Douglas; Truch, Matthew D P; Valiante, Elisabetta; Viero, Marco P; Wiebe, Donald V

    2010-01-01

    We constrain the evolution of the rest-frame far-infrared (FIR) luminosity function out to z~3.5 by combining several pieces of complementary information provided by the deep Balloon-borne Large-Aperture Submillimeter Telescope surveys at 250, 350 and 500 micron, as well as other FIR and millimeter data. Unlike most other phenomenological models, we characterize the uncertainties in our fitted parameters using Monte Carlo Markov Chains. We specifically use the surface density of sources, Cosmic Infrared Background measurements and redshift distributions of bright sources for which identifications have been made. The precise evolution of the FIR luminosity function across this crucial range has eluded studies at longer wavelengths (e.g., using SCUBA and MAMBO) and at shorter wavelengths (e.g., with Spitzer), and now provides a key piece of information required for the study of massive galaxy evolution. Our adoption of Monte Carlo methods enables us not only to find the best-fit evolution model, but also to exp...

  12. The Faint End of the Quasar Luminosity Function at z~4

    CERN Document Server

    Glikman, Eilat; Djorgovski, S G; Stern, Daniel; Dey, Arjun; Jannuzi, Buell T; Mahabal, Ashish

    2009-01-01

    We have conducted a spectroscopic survey to find faint quasars (-26.0 < M_{1450} < -22.0) at redshifts z=3.8-5.2 in order to measure the faint end of the quasar luminosity function at these early times. Using available optical imaging data from portions of the NOAO Deep Wide-Field Survey and the Deep Lens Survey, we have color-selected quasar candidates in a total area of 3.76 deg^2. Thirty candidates have R <= 23 mags. We conducted spectroscopic followup for 28 of our candidates and found 23 QSOs, 21 of which are reported here for the first time, in the 3.74 < z <5.06 redshift range. We estimate our survey completeness through detailed Monte Carlo simulations and derive the first measurement of the density of quasars in this magnitude and redshift interval. We find that the binned luminosity function is somewhat affected by the K-correction used to compute the rest-frame absolute magnitude at 1450A. Considering only our R <= 23 sample, the best-fit single power-law (Phi \\propto L^beta) give...

  13. Distortion of the luminosity function of high-redshift galaxies by gravitational lensing

    CERN Document Server

    Fialkov, Anastasia

    2015-01-01

    The observed properties of high redshift galaxies depend on the underlying foreground distribution of large scale structure, which distorts their intrinsic properties via gravitational lensing. We focus on the regime where the dominant contribution originates from a single lens and examine the statistics of gravitational lensing by a population of virialized and non-virialized structures using sub-mm galaxies at z ~ 2.6 and Lyman-break galaxies at redshifts z ~ 6-15 as the background sources. We quantify the effect of lensing on the luminosity function of the high redshift sources, focusing on the intermediate and small magnifications (mu < 3) which affect the majority of the background galaxies. We show that depending on the intrinsic properties of the background galaxies, gravitational lensing can significantly affect the observed luminosity function even when no obvious strong lenses are present. Finally, we find that in the case of the Lyman-break galaxies it is important to account for the surface bri...

  14. High-energy neutrino fluxes from AGN populations inferred from X-ray surveys

    CERN Document Server

    Jacobsen, Idunn B; On, Alvina Y L; Saxton, Curtis J

    2015-01-01

    High-energy neutrinos and photons are complementary messengers, probing violent astrophysical processes and structural evolution of the Universe. X-ray and neutrino observations jointly constrain conditions in active galactic nuclei (AGN) jets: their baryonic and leptonic contents, and particle production efficiency. Testing two standard neutrino production models for local source Cen A \\citep{KT2008,BB2009}, we calculate the high-energy neutrino spectra of single AGN sources and derive the flux of high-energy neutrinos expected for the current epoch. Assuming that accretion determines both X-rays and particle creation, our parametric scaling relations predict neutrino yield in various AGN classes. We derive redshift-dependent number densities of each class, from {\\it Chandra} and {\\it Swift}/BAT X-ray luminosity functions \\citep{SGB2008,ACS2009}. We integrate the neutrino spectrum expected from the cumulative history of AGN (correcting for cosmological and source effects, e.g. jet orientation and beaming). B...

  15. Star formation in AGN hosts in GOODS-N

    CERN Document Server

    Shao, L; Nordon, R; Maiolino, R; Alexander, D M; Altieri, B; Andreani, P; Aussel, H; Bauer, F E; Berta, S; Bongiovanni, A; Brandt, W N; Brusa, M; Cava, A; Cepa, J; Cimatti, A; Daddi, E; Dominguez-Sanchez, H; Elbaz, D; Schreiber, N M Forster; Geis, N; Genzel, R; Grazian, A; Gruppioni, C; Magdis, G; Magnelli, B; Mainieri, V; Garcia, A M Perez; Poglitsch, A; Popesso, P; Pozzi, F; Riguccini, L; Rodighiero, G; Rovilos, E; Saintonge, A; Salvato, M; Portal, M Sanchez; Santini, P; Sturm, E; Tacconi, L J; Valtchanov, I; Wetzstein, M; Wieprecht, E

    2010-01-01

    Sensitive Herschel far-infrared observations can break degeneracies that were inherent to previous studies of star formation in high-z AGN hosts. Combining PACS 100 and 160um observations of the GOODS-N field with 2Msec Chandra data, we detect ~20% of X-ray AGN individually at >3sig. The host far-infrared luminosity of AGN with L2-10~10^43erg/s increases with redshift by an order of magnitude from z=0 to z~1. In contrast, there is little dependence of far-infrared luminosity on AGN luminosity, for L2-10~1. We do not find a dependence of far-infrared luminosity on X-ray obscuring column, for our sample which is dominated by L2-10<10^44erg/s AGN. In conjunction with properties of local and luminous high-z AGN, we interpret these results as reflecting the interplay between two paths of AGN/host coevolution. A correlation of AGN luminosity and host star formation is traced locally over a wide range of luminosities and also extends to luminous high z AGN. This correlation reflects an evolutionary connection, li...

  16. The luminosity function of cluster galaxies relations among M$_{1}$, M* and the morphological type

    CERN Document Server

    Trevese, D; Appodia, B

    1996-01-01

    A study of the luminosity function of 36 Abell clusters of galaxies has been carried out using photographic plates obtained with the Palomar 1.2 m Schmidt telescope. The relation between the magnitude M_1 of the brightest cluster member and the Schechter function parameter M* has been analyzed. A positive correlation between M* and M_1 is found. However clusters appear segregated in the M_1-M* plane according to their Rood & Sastry class in such a way that on average M_1 becomes brighter while M* becomes fainter going from late to early Rood & Sastry and also Bautz & Morgan classes. Also a partial correlation analysis involving the magnitude M_10 of the 10th brightest galaxy, shows a negative intrinsic correlation between M_1 and M*. These results agree with the cannibalism model for the formation of brightest cluster members, and provide new constraints for theories of cluster formation and evolution.

  17. THE GALAXY LUMINOSITY FUNCTIONS DOWN TO MR = –10 IN THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to MR = –10 at three fields located at the center, intermediate, and outskirt of the cluster. The LF (–19 R R ∼ –13 and is composed of two distinct components of different slopes; the bright component with –19 R R R R < –10) consists largely of point-spread-function-like compact galaxies. We found that both these compact galaxies and some extended galaxies are present in the center while only compact galaxies are seen in the outskirt. In the faint component, the fraction of blue galaxies is larger in the outskirt than in the center. We suggest that the dwarf galaxies in the Coma Cluster, which make up the two components in the LF, are heterogeneous with some different origins.

  18. The luminosity function of the brightest galaxies in the IRAS survey

    Science.gov (United States)

    Soifer, B. T.; Sanders, D. B.; Madore, B. F.; Neugebauer, G.; Persson, C. J.; Persson, S. E.; Rice, W. L.

    1987-01-01

    Results from a study of the far infrared properties of the brightest galaxies in the IRAS survey are described. There is a correlation between the infrared luminosity and the infrared to optical luminosity ratio and between the infrared luminosity and the far infrared color temperature in these galaxies. The infrared bright galaxies represent a significant component of extragalactic objects in the local universe, being comparable in space density to the Seyferts, optically identified starburst galaxies, and more numerous than quasars at the same bolometric luminosity. The far infrared luminosity in the local universe is approximately 25% of the starlight output in the same volume.

  19. Luminosity of ultrahigh energy cosmic rays and bounds on magnetic luminosity of radio-loud active galactic nuclei

    CERN Document Server

    Coimbra-Araújo, C H

    2015-01-01

    We investigate the production of magnetic flux from rotating black holes in active galactic nuclei (AGNs) and compare it with the upper limit of ultrahigh energy cosmic ray (UHECR) luminosities, calculated from observed integral flux of GeV-TeV gamma rays for nine UHECR AGN sources. We find that, for the expected range of black hole rotations (0.44luminosities from AGNs coincides with the calculated UHECR luminosity. We argue that such result possibly can contribute to constrain AGN magnetic and dynamic properties as phenomenological tools to explain the requisite conditions to proper accelerate the highest energy cosmic rays.

  20. Luminosity function of [OII] emission-line galaxies in the MassiveBlack-II simulation

    CERN Document Server

    Park, KwangHo; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M; Feng, Yu; Khandai, Nishikanta

    2015-01-01

    We examine the luminosity function (LF) of [OII] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at $0.06 \\le z \\le 3.0$ using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the GAMA survey. We show that the [OII] LF at z=1.0 from the MBII shows a good agreement with the LFs from several surveys below L([OII])=$10^{43.0}$ erg/s while the low redshifts ($z \\le 0.3$) show an excess in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII])=$10^{41.6}$ erg/s. Based on the validity in reproducing the properties of [OII] galaxies at low redshift ($z \\le 1$), we forecast the evolution of the [OII] LF at high redshift ($z \\le 3$), which can be tested by upcoming surveys such as the HETDEX and DESI. The slopes of the LFs at bright and faint ends range from -3...

  1. Galaxy luminosities, stellar masses, sizes, velocity dispersions as a function of morphological type

    CERN Document Server

    Bernardi, M; Hyde, J B; Mei, S; Marulli, F; Sheth, R K

    2009-01-01

    We provide fits to the distribution of galaxy luminosity, size, velocity dispersion and stellar mass as a function of concentration index C_r and morphological type in the SDSS. We also quantify how estimates of the fraction of `early' or `late' type galaxies depend on whether the samples were cut in color, concentration or light profile shape, and compare with similar estimates based on morphology. Our fits show that Es account for about 20% of the r-band luminosity density, rho_Lr, and 25% of the stellar mass density, rho_*; including S0s and Sas increases these numbers to 33% and 40%, and 50% and 60%, respectively. Summed over all galaxy types, we find rho_* ~ 3 * 10^8 M_Sun Mpc^{-3} at z ~ 0. This is in good agreement with expectations based on integrating the star formation history. However, compared to most previous work, we find an excess of objects at large masses, up to a factor of ~ 10 at M_* ~ 5*10^{11} M_Sun. The stellar mass density further increases at large masses if we assume different IMFs fo...

  2. A Multivariate Fit Luminosity Function and World Model for Long GRBs

    CERN Document Server

    Shahmoradi, Amir

    2012-01-01

    It is proposed that the luminosity function, the comoving-frame spectral correlations and distributions of cosmological Long-duration Gamma-Ray Bursts (LGRBs) may be very well described as multivariate log-normal distribution. This result is based on careful selection, analysis and modeling of the spectral parameters of LGRBs in the largest catalog of Gamma-Ray Bursts available to date: 2130 BATSE GRBs, while taking into account the detection threshold and possible selection effects on observational data. Constraints on the joint quadru-variate distribution of the isotropic peak luminosity, the total isotropic emission, the comoving-frame time-integrated spectral peak energy and the comoving-frame duration of LGRBs are derived. Extensive goodness-of-fit tests are performed. The presented analysis provides evidence for a relatively large fraction of LGRBs that have been missed by BATSE detector with total isotropic emissions extending down to 10^49 [erg] and observed spectral peak energies as low as 5 [KeV]. T...

  3. THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z ∼ 4

    International Nuclear Information System (INIS)

    The evolution of the quasar luminosity function (QLF) is one of the basic cosmological measures providing insight into structure formation and mass assembly in the universe. We have conducted a spectroscopic survey to find faint quasars (-26.0 1450 2. Thirty candidates have R ≤ 23 mag. We conducted spectroscopic follow-up for 28 of our candidates and found 23 QSOs, 21 of which are reported here for the first time, in the 3.74 β) gives a faint-end slope β = -1.6 ± 0.2. If we consider our larger, but highly incomplete sample going 1 mag fainter, we measure a steeper faint-end slope -2 < β < -2.5. In all cases, we consistently find faint-end slopes that are steeper than expected based on measurements at z ∼ 3. We combine our sample with bright quasars from the Sloan Digital Sky Survey to derive parameters for a double-power-law LF. Our best fit finds a bright-end slope, α = -2.4 ± 0.2, and faint-end slope, β = -2.3 ± 0.2, without a well-constrained break luminosity. This is effectively a single power law, with β = -2.7 ± 0.1. We use these results to place limits on the amount of ultraviolet radiation produced by quasars and find that quasars are able to ionize the intergalactic medium at these redshifts.

  4. The evolution of the [OII], H{\\beta} and [OIII] emission-line luminosity functions

    CERN Document Server

    Comparat, Johan; Perez-Gonzalez, Violeta; Norberg, Peder; Newman, Jeffrey; Tresse, Laurence; Richard, Johan; Yepes, Gustavo; Kneib, Jean-Paul; Raichoor, Anand; Prada, Francisco; Maraston, Claudia; Yèche, Christophe; Delubac, Timothée; Jullo, Eric

    2016-01-01

    Emission-line galaxies (ELGs) are one of the main tracers of the large-scale structure to be targeted by the next-generation dark energy surveys. To provide a better understanding of the properties and statistics of these galaxies, we have collected spectroscopic data from the VVDS and DEEP2 deep surveys and estimated the galaxy luminosity functions (LFs) of three distinct emission lines, [OII], H$\\beta$ and [OIII] at redshifts ($0.2 < z < 1.3$). Our measurements are based on the largest sample so far. We present the first measurement of the \\Hb LF at these redshifts. We have also compiled LFs from the literature that were based on independent data or covered different redshift ranges, and we fit the entire set over the whole redshift range with analytic Schechter and Saunders models, assuming a natural redshift dependence of the parameters. We find that the characteristic luminosity ($L_*$) and density ($\\phi_*$) of all LFs increase with redshift. Using the Schechter model, we find that $L^*$ of [OII] ...

  5. Differential Evolution of the UV Luminosity Function of Lyman Break Galaxies from z~5 to 3

    CERN Document Server

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

    2007-01-01

    (abridged) We report the UV luminosity function (LF) of Lyman break galaxies at z~5 derived from a deep and wide survey using the Subaru/Suprime-Cam. Target fields consist of two blank regions of the sky (the HDF-N and J0053+1234), and the total effective surveyed area is 1290 sqarcmin. Applications of carefully determined colour selection criteria in V-I and I-z' yield a detection of 853 candidates with z'AB=L*_z=3) LBGs from that at z~3, while there is a significant decline in the LF's faint end with increasing lookback time. This result means that the evolution of the number densities is differential with UV luminosity: the number density of UV luminous objects remains almost constant from z~5 to 3 while the number density of fainter objects gradually increases with cosmic time. This trend becomes apparent thanks to the small uncertainties in number densities both in the bright and faint parts of LFs at different epochs that are made possible by the deep and wide surveys. We discuss the origins of this dif...

  6. Effects of variability of X-ray binaries on the X-ray luminosity functions of Milky Way

    CERN Document Server

    Islam, Nazma

    2016-01-01

    The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of slope of both HMXB and LMXB XLFs are due to inclusion of variable luminosities of X-ray binaries in construction of these XLFs as well as finite sample effects. XLFs constructed for galactic HMXBs in the luminosity range 10^{36} - 10^{39} erg/sec is described by a power-law model with a mean power-law index of -0.48 and a spread due to variability of HMXBs as 0.19. XLFs constructed for galactic LMXBs in the luminosity r...

  7. Global survey of star clusters in the Milky Way. V. Integrated JHKS magnitudes and luminosity functions

    Science.gov (United States)

    Kharchenko, N. V.; Piskunov, A. E.; Schilbach, E.; Röser, S.; Scholz, R.-D.

    2016-01-01

    Aims: In this study we determine absolute integrated magnitudes in the J,H,KS passbands for Galactic star clusters from the Milky Way Star Clusters survey. In the wide solar neighbourhood, we derive the open cluster luminosity function (CLF) for different cluster ages. Methods: The integrated magnitudes are based on uniform cluster membership derived from the 2MAst catalogue (a merger of the PPMXL and 2MASS) and are computed by summing up the individual luminosities of the most reliable cluster members. We discuss two different techniques of constructing the CLF, a magnitude-limited and a distance-limited approach. Results: Absolute J,H,KS integrated magnitudes are obtained for 3061 open clusters, and 147 globular clusters. The integrated magnitudes and colours are accurate to about 0.8 and 0.2 mag, respectively. Based on the sample of open clusters we construct the general cluster luminosity function in the solar neighbourhood in the three passbands. In each passband the CLF shows a linear part covering a range of 6 to 7 mag at the bright end. The CLFs reach their maxima at an absolute magnitude of -2 mag, then drop by one order of magnitude. During cluster evolution, the CLF changes its slope within tight, but well-defined limits. The CLF of the youngest clusters has a steep slope of about 0.4 at bright magnitudes and a quasi-flat portion for faint clusters. For the oldest population, we find a flatter function with a slope of about 0.2. The CLFs at Galactocentric radii smaller than that of the solar circle differ from those in the direction of the Galactic anti-centre. The CLF in the inner area is flatter and the cluster surface density higher than the local one. In contrast, the CLF is somewhat steeper than the local one in the outer disk, and the surface density is lower. The corresponding catalogue of integrated magnitudes is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  8. On the Cosmological Evolution of the Luminosity Function and the Accretion Rate of Quasars

    International Nuclear Information System (INIS)

    We consider a class of models for the redshift evolution (between 0(less-or-similar sign)z(less-or-similar sign)4) of the observed optical and X-ray quasar luminosity functions (LFs), with the following assumptions: (1) the mass function of dark matter halos follows the Press-Schechter theory, (2) the black hole (BH) mass scales linearly with the halo mass, (3) quasars have a constant universal lifetime, and (4) a thin accretion disk provides the optical luminosity of quasars, while the X-ray/optical flux ratio is calibrated from a sample of observed quasars. The mass accretion rate, M, onto quasar BHs is a free parameter of the models, which we constrain using the observed LFs. The accretion rate M inferred from either the optical or X-ray data under these assumptions generally decreases as a function of cosmic time from z≅4 to z≅0. We find that a comparable accretion rate is inferred from the X-ray and optical LF only if the X-ray/optical flux ratio decreases with BH mass. Near z≅0, M drops to substantially sub-Eddington values at which advection-dominated accretion flows (ADAFs) exist. Such a decline of M, possibly followed by a transition to radiatively inefficient ADAFs, could explain both the absence of bright quasars in the local universe and the faintness of accreting BHs at the centers of nearby galaxies. We argue that a decline of the accretion rate of the quasar population is indeed expected in cosmological structure formation models. (c) 2000 The American Astronomical Society

  9. The WARPS Survey - VIII. Evolution of the galaxy cluster X-ray Luminosity Function

    Science.gov (United States)

    Koens, L. A.; Maughan, B. J.; Jones, L. R.; Ebeling, H.; Horner, D. J.; Perlman, E. S.; Phillipps, S.; Scharf, C. A.

    2013-11-01

    We present measurements of the galaxy cluster X-ray Luminosity Function (XLF) from the Wide Angle ROSAT Pointed Survey (WARPS) and quantify its evolution. WARPS is a serendipitous survey of the central region of ROSAT pointed observations and was carried out in two phases (WARPS-I and WARPS-II). The results here are based on a final sample of 124 clusters, complete above a flux limit of 6.5 × 10-14 erg cm-2 s-1, with members out to redshift z ˜ 1.05, and a sky coverage of 70.9 deg2. We find significant evidence for negative evolution of the XLF, which complements the majority of X-ray cluster surveys. To quantify the suggested evolution, we perform a maximum likelihood analysis and conclude that the evolution is driven by a decreasing number density of high-luminosity clusters with redshift, while the bulk of the cluster population remains nearly unchanged out to redshift z ≈ 1.1, as expected in a low-density universe. The results are found to be insensitive to a variety of sources of systematic uncertainty that affect the measurement of the XLF and determination of the survey selection function. We perform a Bayesian analysis of the XLF to fully account for uncertainties in the local XLF on the measured evolution, and find that the detected evolution remains significant at the 95 per cent level. We observe a significant excess of clusters in the WARPS at 0.1 WARPS data. We find that the excess cannot be explained by sample variance, or Eddington bias, and is unlikely to be due to problems with the survey selection function.

  10. The HerMES submillimetre local and low-redshift luminosity functions

    Science.gov (United States)

    Marchetti, L.; Vaccari, M.; Franceschini, A.; Arumugam, V.; Aussel, H.; Béthermin, M.; Bock, J.; Boselli, A.; Buat, V.; Burgarella, D.; Clements, D. L.; Conley, A.; Conversi, L.; Cooray, A.; Dowell, C. D.; Farrah, D.; Feltre, A.; Glenn, J.; Griffin, M.; Hatziminaoglou, E.; Heinis, S.; Ibar, E.; Ivison, R. J.; Nguyen, H. T.; O'Halloran, B.; Oliver, S. J.; Page, M. J.; Papageorgiou, A.; Pearson, C. P.; Pérez-Fournon, I.; Pohlen, M.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Schulz, B.; Scott, Douglas; Seymour, N.; Shupe, D. L.; Smith, A. J.; Symeonidis, M.; Valtchanov, I.; Viero, M.; Wang, L.; Wardlow, J.; Xu, C. K.; Zemcov, M.

    2016-02-01

    We used wide-area surveys over 39 deg2 by the HerMES (Herschel Multi-tiered Extragalactic Survey) collaboration, performed with the Herschel Observatory SPIRE multiwavelength camera, to estimate the low-redshift, 0.02 < z < 0.5, monochromatic luminosity functions (LFs) of galaxies at 250, 350 and 500 μm. Within this redshift interval, we detected 7087 sources in five independent sky areas, ˜40 per cent of which have spectroscopic redshifts, while for the remaining objects photometric redshifts were used. The SPIRE LFs in different fields did not show any field-to-field variations beyond the small differences to be expected from cosmic variance. SPIRE flux densities were also combined with Spitzer photometry and multiwavelength archival data to perform a complete spectral energy distribution fitting analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric infrared (IR; 8-1000 μm) LFs and their low-z evolution from a combination of statistical estimators. Integration of the latter prompted us to also compute the local luminosity density and the comoving star formation rate density (SFRD) for our sources, and to compare them with theoretical predictions of galaxy formation models. The LFs show significant and rapid luminosity evolution already at low redshifts, 0.02 < z < 0.2, with L_{IR}^{*} ∝ (1+z)^{6.0± 0.4} and Φ _{IR}^{*} ∝ (1+z)^{-2.1± 0.4}, L_{250}^{*} ∝ (1+z)^{5.3± 0.2} and Φ _{250}^{*} ∝ (1+z)^{-0.6± 0.4} estimated using the IR bolometric and the 250 μm LFs, respectively. Converting our IR LD estimate into an SFRD assuming a standard Salpeter initial mass function and including the unobscured contribution based on the UV dust-uncorrected emission from local galaxies, we estimate an SFRD scaling of SFRD0 + 0.08z, where SFRD0 ≃ (1.9 ± 0.03) × 10-2 [M⊙ Mpc-3] is our total SFRD estimate at z ˜ 0.02.

  11. The Global 21-cm Signal in the Context of the High-z Galaxy Luminosity Function

    CERN Document Server

    Mirocha, Jordan; Sun, G

    2016-01-01

    Motivated by recent progress in studies of the high-$z$ Universe, we build a new model for the global 21-cm signal that is explicitly calibrated to measurements of the galaxy luminosity function (LF) and further tuned to match the Thomson scattering optical depth of the cosmic microwave background, $\\tau_e$. Assuming that the $z \\lesssim 8$ galaxy population can be smoothly extrapolated to higher redshifts, the recent decline in best-fit values of $\\tau_e$ and the inefficient heating induced by X-ray binaries (HMXBs; the presumptive sources of the X-ray background at high-$z$) imply that the entirety of cosmic reionization and reheating occurs at redshifts $z \\lesssim 12$. In contrast to past global 21-cm models, whose $z \\sim 20$ ($\

  12. Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function

    CERN Document Server

    Dotti, Massimo; Montuori, Carmen

    2015-01-01

    Massive black hole binaries are naturally predicted in the context of the hierarchical model of structure formation. The binaries that manage to lose most of their angular momentum can coalesce to form a single remnant. In the last stages of this process, the holes undergo an extremely loud phase of gravitational wave emission, possibly detectable by current and future probes. The theoretical effort towards obtaining a coherent physical picture of the binary path down to coalescence is still underway. In this paper, for the first time, we take advantage of observational studies of active galactic nuclei evolution to constrain the efficiency of gas-driven binary decay. Under conservative assumptions we find that gas accretion toward the nuclear black holes can efficiently lead binaries of any mass forming at high redshift (> 2) to coalescence within the current time. The observed "downsizing" trend of the accreting black hole luminosity function further implies that the gas inflow is sufficient to drive light ...

  13. THE FAINT END OF THE CLUSTER-GALAXY LUMINOSITY FUNCTION AT HIGH REDSHIFT

    International Nuclear Information System (INIS)

    We measure the faint-end slope of the galaxy luminosity function (LF) for cluster galaxies at 1 3.6μm = –0.97 ± 0.14 and α4.5μm = –0.91 ± 0.28, consistent with a flat faint-end slope and is in agreement with measurements of the field LF in similar bands at these redshifts. A comparison to α in low-redshift clusters finds no statistically significant evidence of evolution. Combined with past studies which show that M* is passively evolving out to z ∼ 1.3, this means that the shape of the cluster LF is largely in place by z ∼ 1.3. This suggests that the processes that govern the buildup of the mass of low-mass cluster galaxies have no net effect on the faint-end slope of the cluster LF at z ∼< 1.3.

  14. The dependence of the Lyman_a luminosity function on Redshift using SHARDS

    CERN Document Server

    Rodriguez-Espinosa, J M; Lopez-Aguerri, J A; Muñoz-Tuñon, C; Perez-Gonzalez, P G; Cava, A

    2012-01-01

    We report in this work on a project aimed at determining Ly{\\alpha} luminosity functions from z=3 to z=6. The project is based on the use of very deep photometry from the SHARDS Survey, in a set of 24 medium band filters in the GOODS-N field. We present here some preliminary work carried out with four test images in four consecutive bands. We use the narrow band selection technique for searching emission line candidates. Eleven candidates have been detected so far, many of which are strong Ly{\\alpha} candidates. In particular, we have seen a firm candidate to an interacting pair of Ly{\\alpha} sources at z=5.4.

  15. Binary Aggregations in Hierarchical Galaxy Formation The Evolution of the Galaxy Luminosity Function

    CERN Document Server

    Menci, N; Fontana, A; Giallongo, E; Poli, F

    2002-01-01

    We develop a semi-analytic model of hierarchical galaxy formation with an improved treatment of the evolution of galaxies inside dark matter haloes. We take into account not only dynamical friction processes building up the central dominant galaxy, but also binary aggregations of satellite galaxies inside a common halo described using the kinetic Smoluchowski equation. The description of gas cooling, star formation and evolution, and Supernova feedback follows the standard prescriptions widely used in semi-analytic modelling. We find that binary aggregations are effective in depleting the number of small/intermediate mass galaxies over the redshift range 1-16. We compare our predicted luminosity functions with those obtained from deep multicolor surveys in the rest-frame B and UV bands for the redshift ranges 01 and even more at z ~ 3 by the effect of binary aggregations. The predictions from our dynamical model are discussed and compared with the effects of complementary processes which may conspire in affec...

  16. Effects of AGN feedback on LCDM galaxies

    CERN Document Server

    Lagos, Claudia del P; Padilla, Nelson D

    2008-01-01

    We study the effects of Active Galactic Nuclei (AGN) feedback on the formation and evolution of galaxies in a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other BHs, (ii) accretion during starbursts triggered by disc instabilities, and (iii) accretion of gas cooled from quasi-hydrostatic hot gas haloes. It is assumed that feedback from AGN operates in the later case. The model has been calibrated in order to reproduce observational correlations between BH mass and mass, velocity dispersion, and absolute magnitudes of the galaxy bulge. AGN feedback has a strong impact on reducing or even suppressing gas cooling, an effect that becomes important at lower redshifts. This phenomenon helps to reproduce the observed galaxy luminosity function (LF) in the optical and near IR bands at z=0, and the cosmic star formation ra...

  17. LOW LUMINOSITY AGN CANDIDATES IN SDSS

    OpenAIRE

    J. P. Torres-Papaqui; R. Coziol; J. M. Islas-Islas; Ortega-Minakata, R. A.; D. M. Neri-Larios

    2011-01-01

    En una muestra de 476931 galaxias con l neas de emisi n agostas del Sloan Digital Sky Survey Data Release 5, identificamos y estudiamos galaxias de las cuales algunas importantes l neas de emisi n usadas para determinar la naturaleza de su actividad ([OIII]h5007 A, H , o ambas) no est an presentes. Este fen meno afecta al 22% de las galaxias con l neas de emisi n y no esta relacionado con una baja raz n de se al a ruido. En el diagrama comparando el ancho equivalente EW([NII]h6584) con la raz...

  18. The Second INTEGRAL AGN Catalogue

    CERN Document Server

    Beckmann, V; Ricci, C; Alfonso-Garzón, J; Courvoisier, T J -L; Domingo, A; Gehrels, N; Lubinski, P; Mas-Hesse, J M; Zdziarski, A A

    2009-01-01

    The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows to test the unified scheme for AGN. We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN that have been reported to be detected by INTEGRAL above 20 keV. The data analysed here allow a significant spectral extraction on 148 objects and optical variability study of 57 AGN. The slopes of the hard X-ray spectra of Seyfert 1 and Seyfert 2 galaxies are found to be consistent within the uncertainties, whereas lower luminosities are measured for the more absorbed / type 2 AGN. The intermediate Seyfert 1.5 objects exhibit hard X-ray spectra consistent with those of Seyfert 1. When applying a Compton reflection model, the underlying continua appear still the same in Seyfert 1 and 2 with photon index 2, and the reflection strength is about R = 1, when assuming different inclination angles. A significant correlation is found between the hard X-ray and optical luminosity and the mass of the centr...

  19. Spatial dependence of 2MASS luminosity and mass functions in the old open cluster NGC 188

    CERN Document Server

    Bonatto, C; Santos, J F C

    2005-01-01

    Luminosity and mass functions in the old open cluster NGC 188 are analysed by means of J and H 2MASS photometry. Within the uncertainties, the observed projected radial density profile of NGC 188 departs from the two-parameter King model in two inner regions, which reflects the non-virialized dynamical state and possibly, some degree of non-sphericity in the spatial shape of this old open cluster. Fits with two and three-parameter King models to the radial distribution of stars resulted in a core radius of 1.3 pc and a tidal radius of 21 pc. The present 2MASS analysis resulted in significant slope variations with distance in the mass function $\\phi(m)\\propto m^{-(1+\\chi)}$, being flat in the central parts ($\\chi=0.6\\pm0.7$) and steep in the cluster outskirts ($\\chi=7.2\\pm0.6$). The overall mass function has a slope $\\chi=1.9\\pm0.7$, slightly steeper than a standard Salpeter mass function. Solar metallicity Padova isochrone fits to the near-infrared colour-magnitude diagram of NGC 188 resulted in an age of $7....

  20. Revisiting the axion bounds from the Galactic white dwarf luminosity function

    International Nuclear Information System (INIS)

    It has been shown that the shape of the luminosity function of white dwarfs (WDLF) is a powerful tool to check for the possible existence of DFSZ-axions, a proposed but not yet detected type of weakly interacting particles. With the aim of deriving new constraints on the axion mass, we compute in this paper new theoretical WDLFs on the basis of WD evolving models that incorporate the feedback of axions on the thermal structure of the white dwarf. We find that the impact of the axion emission into the neutrino emission can not be neglected at high luminosities M Bol∼< 8) and that the axion emission needs to be incorporated self-consistently into the evolution of the white dwarfs when dealing with axion masses larger than ma cos 2β∼> 5 meV (i.e. axion-electron coupling constant gae∼> 1.4× 10-13). We went beyond previous works by including 5 different derivations of the WDLF in our analysis. Then we have performed χ2-tests to have a quantitative measure of the agreement between the theoretical WDLFs — computed under the assumptions of different axion masses and normalization methods --- and the observed WDLFs of the Galactic disk. While all the WDLF studied in this work disfavour axion masses in the range suggested by asteroseismology ma cos 2β∼> 10 meV; gae∼> 2.8× 10-13) lower axion masses can not be discarded from our current knowledge of the WDLF of the Galactic Disk. A larger set of completely independent derivations of the WDLF of the galactic disk as well as a detailed study of the uncertainties of the theoretical WDLFs is needed before quantitative constraints on the axion-electron coupling constant can be made

  1. ACCESS: NIR Luminosity and Stellar Mass Function of Galaxies in the Shapley Supercluster Environment

    CERN Document Server

    Merluzzi, P; Haines, C P; Smith, R J; Busarello, G; Lucey, J R

    2009-01-01

    We present the NIR luminosity (LF) and stellar mass functions (SMF) of galaxies in the core of the Shapley supercluster at z=0.048, based on new K-band observations in conjunction with B- and R-band photometry and a subsample of ~650 galaxies spectroscopically confirmed supercluster members, allowing to investigate the galaxies down to M_K^*+6 and M=10^8.75 M_sun. For the 3 deg^2 field the K-band LF is described by a Schechter function with M_K^*=-24.96+-0.10 and \\alpha=-1.42+-0.03. We investigate the effect of environment by deriving the LF in three regions selected according to the local galaxy density, and observe a significant increase in the faint-end slope going from the high- (\\alpha=-1.33) to the low-density (\\alpha=-1.49) environments. The SMF is fitted well by a Schechter function with log_10(M^*)=11.16+-0.04 and \\alpha=-1.20+-0.02. The SMF of supercluster galaxies is also characterised by an excess of massive galaxies that are associated to the cluster BCGs. While the value of M* depends on environ...

  2. The near-infrared luminosity function of cluster galaxies beyond redshift one

    CERN Document Server

    Strazzullo, V; Eisenhardt, P E; Ettori, S; Lidman, C; Mainieri, V; Nonino, M; Rosati, P; Stanford, S A; Toft, S; Toft, and S.

    2006-01-01

    We determined the K band luminosity function (LF) of cluster galaxies at redshift z~1.2, using near-infrared images of three X-ray luminous clusters at z=1.11,1.24,1.27. The composite LF was derived down to M*+4, by means of statistical background subtraction, and is well described by a Schechter function with K*=20.5 AB mag and alpha=-1. From the K band composite LF we derived the stellar mass function of cluster galaxies. Using available X-ray mass profiles we determined the M/L ratios of these three clusters, which tend to be lower than those measured in the local universe. With these data, no significant difference can be seen between the shapes of the cluster galaxies LF and the LF of field galaxies at similar redshift. We also found no significant evolution out to z ~1.2 in the bright (2. The results obtained in this work support and extend previous findings that most of the stars in bright galaxies were formed at high redshift, and that K-bright (M>10^11 Msun) galaxies were already in place at z ~ 1.2,...

  3. The initial luminosity and mass functions of the Galactic open clusters

    CERN Document Server

    Piskunov, A E; Schilbach, E; Röser, S; Scholz, R -D; Zinnecker, H

    2008-01-01

    (... abridged) The observed luminosity function can be constructed in a range of absolute integrated magnitudes $I_{M_V}= [-10, -0.5]$ mag, i.e. about 5 magnitudes deeper than in the most nearby galaxies. It increases linearly from the brightest limit to a turnover at about $I_{M_V}\\approx-2.5$. The slope of this linear portion is $a=0.41\\pm0.01$, which agrees perfectly with the slope deduced for star cluster observations in nearby galaxies. (...) We find that the initial mass function of open clusters (CIMF) has a two-segment structure with the slopes $\\alpha=1.66\\pm0.14$ in the range $\\log M_c/M_\\odot=3.37...4.93$ and $\\alpha=0.82\\pm0.14$ in the range $\\log M_c/M_\\odot=1.7...3.37$. The average mass of open clusters at birth is $4.5\\cdot 10^3 M_\\odot$, which should be compared to the average observed mass of about $700 M_\\odot$. The average cluster formation rate derived from the comparison of initial and observed mass functions is $\\bar{\\upsilon}=0.4 \\mathrm{kpc}^{-2}\\mathrm{Myr}^{-1}$. Multiplying by the a...

  4. ACTIVE GALACTIC NUCLEI AS MAIN CONTRIBUTORS TO THE ULTRAVIOLET IONIZING EMISSIVITY AT HIGH REDSHIFTS: PREDICTIONS FROM A {Lambda}-CDM MODEL WITH LINKED AGN/GALAXY EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Giallongo, E.; Menci, N.; Fiore, F.; Castellano, M.; Fontana, A.; Grazian, A.; Pentericci, L. [INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy)

    2012-08-20

    We have evaluated the contribution of the active galactic nuclei (AGN) population to the ionization history of the universe based on a semi-analytic model of galaxy formation and evolution in the cold dark matter cosmological scenario. The model connects the growth of black holes and of the ensuing AGN activity to galaxy interactions. In the model we have included a self-consistent physical description of the escape of ionizing UV photons; this is based on the blast-wave model for the AGN feedback we developed in a previous paper to explain the distribution of hydrogen column densities in AGNs of various redshifts and luminosities, due to absorption by the host galaxy gas. The model predicts UV luminosity functions for AGNs that are in good agreement with those derived from the observations especially at low and intermediate redshifts (z {approx} 3). At higher redshifts (z > 5), the model tends to overestimate the data at faint luminosities. Critical biases in both the data and in the model are discussed to explain such apparent discrepancies. The predicted hydrogen photoionization rate as a function of redshift is found to be consistent with that derived from the observations. All of the above suggests that we should reconsider the role of the AGNs as the main driver of the ionization history of the universe.

  5. The First INTEGRAL AGN Catalog

    CERN Document Server

    Beckmann, V; Shrader, C R; Soldi, S

    2006-01-01

    We present the first INTEGRAL AGN catalog, based on observations performed from launch of the mission in October 2002 until January 2004. The catalog includes 42 AGN, of which 10 are Seyfert 1, 17 are Seyfert 2, and 9 are intermediate Seyfert 1.5. The fraction of blazars is rather small with 5 detected objects, and only one galaxy cluster and no star-burst galaxies have been detected so far. A complete subset consists of 32 AGN with a significance limit of 7 sigma in the INTEGRAL/ISGRI 20-40 keV data. Although the sample is not flux limited, the distribution of sources shows a ratio of obscured to unobscured AGN of 1.5 - 2.0, consistent with luminosity dependent unified models for AGN. Only four Compton-thick AGN are found in the sample. Based on the INTEGRAL data presented here, the Seyfert 2 spectra are slightly harder (Gamma = 1.95 +- 0.01) than Seyfert 1.5 (Gamma = 2.10 +- 0.02) and Seyfert 1 (Gamma = 2.11 +- 0.05).

  6. The XXL Survey. II. The bright cluster sample: catalogue and luminosity function

    Science.gov (United States)

    Pacaud, F.; Clerc, N.; Giles, P. A.; Adami, C.; Sadibekova, T.; Pierre, M.; Maughan, B. J.; Lieu, M.; Le Fèvre, J. P.; Alis, S.; Altieri, B.; Ardila, F.; Baldry, I.; Benoist, C.; Birkinshaw, M.; Chiappetti, L.; Démoclès, J.; Eckert, D.; Evrard, A. E.; Faccioli, L.; Gastaldello, F.; Guennou, L.; Horellou, C.; Iovino, A.; Koulouridis, E.; Le Brun, V.; Lidman, C.; Liske, J.; Maurogordato, S.; Menanteau, F.; Owers, M.; Poggianti, B.; Pomarède, D.; Pompei, E.; Ponman, T. J.; Rapetti, D.; Reiprich, T. H.; Smith, G. P.; Tuffs, R.; Valageas, P.; Valtchanov, I.; Willis, J. P.; Ziparo, F.

    2016-06-01

    Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of ~2 at a sensitivity of ~10-14 erg s-1 cm-2 in the [0.5-2] keV band. Aims: This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 × 10-14 erg s-1 cm-2 on the source flux within a 1' aperture. Methods: The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results: The bright cluster sample consists of systems with masses between M500 = 7 × 1013 and 3 × 1014 M⊙, mostly located between z = 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of σ8 and/or ΩM appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z ~ 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters. Based on

  7. Galaxy Luminosity Function of Dynamically Young Abell 119 Cluster: Probing the Cluster Assembly

    CERN Document Server

    Lee, Youngdae; Hilker, Michael; Sheen, Yun-Kyeong; Yi, Sukyoung K

    2016-01-01

    We present the galaxy luminosity function (LF) of the Abell 119 cluster down to $M_r\\sim-14$ mag based on deep images in the $u$-, $g$-, and $r$-bands taken by using MOSAIC II CCD mounted on the Blanco 4m telescope at the CTIO. The cluster membership was accurately determined based on the radial velocity information as well as on the color-magnitude relation for bright galaxies and the scaling relation for faint galaxies. The overall LF exhibits a bimodal behavior with a distinct dip at $r\\sim18.5$ mag ($M_r\\sim-17.8$ mag), which is more appropriately described by a two-component function. The shape of the LF strongly depends on the cluster-centric distance and on the local galaxy density. The LF of galaxies in the outer, low-density region exhibits a steeper slope and more prominent dip compared with that of counterparts in the inner, high-density region. We found evidence for a substructure in the projected galaxy distribution in which several overdense regions in the Abell 119 cluster appear to be closely ...

  8. The Properties of Poor Groups of Galaxies; 3, The Galaxy Luminosity Function

    CERN Document Server

    Zabludoff, A I; Zabludoff, Ann I.; Mulchaey, John S.

    2000-01-01

    We obtain R-band photometry for galaxies in six nearby poor groups for which we have spectroscopic data, including 328 new galaxy velocities. For the five groups with luminous X-ray halos, the composite group galaxy luminosity function (GLF) is fit adequately by a Schechter function with Mstar = -21.6 +/- 0.4 + 5log h and alpha = -1.3 +/- 0.1. We also find that (1) the ratio of dwarfs to giants is significantly larger for the five groups with luminous X-ray halos than for the one marginally X-ray detected group, (2) the composite GLF for the luminous X-ray groups is consistent in shape with that for rich clusters, (3) the composite group GLF rises more steeply at the faint end than that of the field, (4) the shape difference between the field and composite group GLF's results mostly from the population of non-emission line galaxies, whose dwarf-to-giant ratio is larger in the denser group environment than in the field, and (5) the non-emission line dwarfs are more concentrated about the group center than the ...

  9. Luminosity and mass functions of the three main sequences of the globular cluster NGC 2808

    CERN Document Server

    Milone, A P; Bedin, L R; Cassisi, S; Anderson, J; Marino, A F; Pietrinferni, A; Aparicio, A

    2011-01-01

    High-precision HST photometry has recently revealed that the globular cluster (GC) NGC 2808 hosts a triple main sequence (MS) corresponding to three stellar populations with different helium abundances. We carried out photometry on ACS/WFC HST images of NGC 2808 with the main purpose of measuring the luminosity function (LF) of stars in the three different MSs, and the binary fraction in the cluster. We used isochrones to transform the observed LFs into mass functions (MFs). We estimated that the fraction of binary systems in NGC 2808 is f_bin ~0.05, and find that the three MSs have very similar LFs. The slopes of the corresponding MFs are alpha=-1.2+/-0.3 for the red MS, alpha =-0.9+/-0.3 for the middle MS, and alpha = -0.9+/-0.4 for the blue one, the same, to within the errors. There is marginal evidence of a MF flattening for masses M<~0.6 M_SUN for the the reddest (primordial) MS. These results represent the first direct measurement of the present day MF and LF in distinct stellar populations of a GC, ...

  10. The Main Sequence Luminosity Function of Low-Mass Globular Clusters

    Science.gov (United States)

    Smith, Graeme

    2009-07-01

    Theoretical work indicates that the dynamical evolution of globular clusters of low mass and low central concentration is strongly determined by mass-loss processes, such as stellar evaporation and tidal stripping, that can eventually lead to cluster dissolution. In fact, mass loss and cluster disruption is now considered to be a viable explanation for the form of the faint end of the Milky Way globular cluster luminosity function. A clear observational demonstration of the prevalence of cluster mass-loss would have ramifications not only for the dynamical evolution of individual globular clusters and their internal stellar mass distributions, but also for the relationships between halo field and cluster stars and the properties of globular cluster systems in galaxies. Our previous WFPC2 imaging of the low-mass diffuse halo cluster Palomar 5 revealed a main sequence deficient in stars compared to other low-concentration globular clusters of much higher mass, consistent with there having been a considerable loss of stars from this system. But is Pal 5 typical of low-mass, low-concentration halo clusters? We propose to place the mass-loss scenario on a firm observational footing {or otherwise} by using WFC3 imaging to measure the main-sequence stellar mass functions of two of the lowest-mass lowest-concentration globular clusters in the Milky Way, AM-4 and Palomar 13, in order to search for analogous evidence of stellar depletion.

  11. The optical luminosity function of gamma-ray bursts deduced from ROTSE-III observations

    International Nuclear Information System (INIS)

    We present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of 58 GRBs from observations with the Robotic Optical Transient Search Experiment III (ROTSE-III). Our GRB sample is divided into two sub-samples: detected afterglows (18 GRBs) and those with upper limits (40 GRBs). We derive R-band fluxes for these two sub-samples 100 s after the onset of the burst. The optical LFs at 100 s are fitted by assuming that the co-moving GRB rate traces the star formation rate. While fitting the optical LFs using Monte Carlo simulations, we take into account the detection function of ROTSE-III. We find that the cumulative distribution of optical emission at 100 s is well described by an exponential rise and power-law decay, a broken power law,and Schechter LFs. A single power-law (SPL) LF, on the other hand, is ruled out with high confidence.

  12. The optical luminosity function of gamma-ray bursts deduced from ROTSE-III observations

    Energy Technology Data Exchange (ETDEWEB)

    Cui, X. H.; Wu, X. F.; Wei, J. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Yuan, F. [Research School of Astronomy and Astrophysics, The Australian National University, Weston Creek, ACT 2611 (Australia); Zheng, W. K. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Liang, E. W. [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Akerlof, C. W.; McKay, T. A. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Ashley, M. C. B. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Flewelling, H. A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Göǧüş, E. [Sabancı University, Orhanlı-Tuzla, 34956 İstanbul (Turkey); Güver, T. [Department of Astronomy and Space Sciences, Istanbul University Science Faculty, 34119 Istanbul (Turkey); Kızıloǧlu, Ü. [Middle East Technical University, 06531 Ankara (Turkey); Pandey, S. B. [ARIES, Manora Peak, Nainital 263129, Uttarakhand (India); Rykoff, E. S. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Rujopakarn, W. [Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330 (Thailand); Schaefer, B. E. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Wheeler, J. C. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Yost, S. A., E-mail: xhcui@bao.ac.cn, E-mail: xfwu@pmo.ac.cn, E-mail: jjwei@pmo.ac.cn, E-mail: fang.yuan@anu.edu.au, E-mail: zwk@astro.berkeley.edu, E-mail: lew@gxu.edu.cn [Department of Physics, College of St. Benedict, St. John' s University, Collegeville, MN 56321 (United States)

    2014-11-10

    We present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of 58 GRBs from observations with the Robotic Optical Transient Search Experiment III (ROTSE-III). Our GRB sample is divided into two sub-samples: detected afterglows (18 GRBs) and those with upper limits (40 GRBs). We derive R-band fluxes for these two sub-samples 100 s after the onset of the burst. The optical LFs at 100 s are fitted by assuming that the co-moving GRB rate traces the star formation rate. While fitting the optical LFs using Monte Carlo simulations, we take into account the detection function of ROTSE-III. We find that the cumulative distribution of optical emission at 100 s is well described by an exponential rise and power-law decay, a broken power law,and Schechter LFs. A single power-law (SPL) LF, on the other hand, is ruled out with high confidence.

  13. Occurence and Luminosity Functions of Giant Radio Halos from Magneto-Turbulent Model

    CERN Document Server

    Cassano, R; Setti, G; Cassano, Rossella; Brunetti, Gianfranco; Setti, Giancarlo

    2004-01-01

    We calculate the probability to form giant radio halos (~ 1 Mpc size) as a function of the mass of the host clusters by using a Statistical Magneto-Turbulent Model (Cassano & Brunetti, these proceedings). We show that the expectations of this model are in good agreement with the observations for viable values of the parameters. In particular, the abrupt increase of the probability to find radio halos in the more massive galaxy clusters (M > 2x10^{15} solar masses) can be well reproduced. We calculate the evolution with redshift of such a probability and find that giant radio halos can be powered by particle acceleration due to MHD turbulence up to z~0.5 in a LCDM cosmology. Finally, we calculate the expected Luminosity Functions of radio halos (RHLFs). At variance with previous studies, the shape of our RHLFs is characterized by the presence of a cut-off at low synchrotron powers which reflects the inefficiency of particle acceleration in the case of less massive galaxy clusters.

  14. Mid- and Far-infrared Luminosity Functions and Galaxy Evolution from Multiwavelength Spitzer Observations up to z~2.5

    CERN Document Server

    Rodighiero, G; Franceschini, A; Tresse, L; Le Fèvre, O; Le Brun, V; Mancini, C; Matute, I; Cimatti, A; Marchetti, L; Ilbert, O; Arnouts, S; Bolzonella, M; Zucca, E; Bardelli, S; Lonsdale, C J; Shupe, D; Surace, J; Rowan-Robinson, M; Garilli, B; Zamorani, G; Pozzetti, L; Bondi, M; De la Torre, S; Vergani, D; Santini, P; Grazian, A; Fontana, A

    2009-01-01

    [Abridged]We exploit a large homogeneous dataset to derive a self-consistent picture of IR emission based on the time-dependent 24, 15, 12 and 8micron monochromatic and bolometric IR luminosity functions (LF) over the 01. The mean redshift of the peak in the source number density shifts with luminosity: the brighest IR galaxies appear to be forming stars earlier in cosmic time (z>1.5), while the less luminous ones keep doing it at more recent epochs (z~1 for L (IR)1. We also seem to find a difference in the evolution rate of the source number densities as a function of luminosity, a downsizing evolutionary pattern similar to that reported from other samples of cosmic sources.

  15. The First Hard X-Ray Power Spectral Density Functions of AGN

    OpenAIRE

    Shimizu, T. Taro; Mushotzky, Richard F.

    2013-01-01

    We present results of our Power Spectral Density (PSD) analysis of 30 AGN using the 58 month light curves from Swift's Burst Alert Telescope (BAT) in the 14-150 keV band. PSDs were fit using a Monte Carlo based algorithm to take into account windowing effects and measurement error. All but one source were found to be fit very well using an unbroken power law with a slope of ~-1, consistent at low frequencies with previous studies in the 2-10 keV band, with no evidence of a break in the PSD. F...

  16. The Eddington Ratio of H2O Maser Host AGN

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2011-03-01

    The Eddington ratio was derived for the entire maser host AGN sample, based on the intrinsic X-ray luminosity, the X-ray bolometric correction X and the mass of central black hole. Further the [O III] bolometric correction [O III] was estimated for our sample. Possible relations were also investigated between the maser luminosity and the bolometric luminosity – the Eddington ratio.

  17. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    OpenAIRE

    Takeuchi, Tsutomu T.

    2010-01-01

    We show an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient $|\\rho|

  18. The environment of AGNs and the activity degree of their surrounding galaxies

    CERN Document Server

    Kollatschny, W; Zetzl, M

    2012-01-01

    Aims. We present results of a comprehensive spectral study on the large-scale environment of AGNs based on Sloan Spectroscopic Survey data. Methods. We analyzed the spectra of galaxies in the environment of AGN and other activity classes up to distances of 1 Mpc. Results. The mean H{\\alpha} and [OIII] {\\lambda}5007 line luminosities in the environmental galaxies within a projected radius of 1 Mpc are highest around Seyfert 1 galaxies, with decreasing luminosities for Seyfert 2 and HII galaxies, and lowest for absorption line galaxies. Furthermore, there is a trend toward H{\\alpha} and [OIII] luminosities in the environmental galaxies increasing as a function of proximity to the central emission line galaxies. There is another clear trend toward a neighborhood effect within a radius of 1000 kpc for the AGN and non-AGN types: Seyfert galaxies tend to have the highest probability of having another Seyfert galaxy in the neighborhood. HII galaxies tend to have the highest probability of having another HII galaxy i...

  19. The Luminosity Function of the Host Galaxies of QSOs and BL Lac Objects

    CERN Document Server

    Carangelo, N; Treves, A

    2001-01-01

    A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties requires images of excellent quality in order to disentangle the light of the galaxy from that of the bright nucleus. To this aim HST has provided a major improvement of data on QSOs (Disney et al. 1995; Bahcall et al. 1996, 1997; Boyce et al. 1998; McLure et al. 1999; Hamilton et al. 2000; Kukula et al. 2001) and BL Lacs (Scarpa et al. 2000, Urry et al. 2000). We present a comparative study of low redshift QSO and BL Lac host galaxy luminosity function (HGLF). To this aim we have considered samples of BL Lacs (Urry et al. 2000) and QSOs (Bahcall et al. 1997; Boyce et al. 1998; McLure et al. 1999) that have been well resolved by images obtained with WFPC2 on board of HST.

  20. The Optical Luminosity Function of Void Galaxies in the SDSS and ALFALFA Surveys

    CERN Document Server

    Moorman, Crystal M; Hoyle, Fiona; Pan, Danny C; Haynes, Martha P; Giovanelli, Riccardo

    2015-01-01

    We measure the r-band galaxy luminosity function (LF) across environments over the redshift range 0<$z$<0.107 using the SDSS. We divide our sample into galaxies residing in large scale voids (void galaxies) and those residing in denser regions (wall galaxies). The best fitting Schechter parameters for void galaxies are: log$\\Phi^*$= -3.40$\\pm$0.03 log(Mpc$^{-3}$), $M^*$= -19.88$\\pm$0.05, and $\\alpha$=-1.20$\\pm$0.02. For wall galaxies, the best fitting parameters are: log$\\Phi^*$=-2.86$\\pm$0.02 log(Mpc$^{-3}$), $M^*$=-20.80$\\pm$0.03, and $\\alpha$=-1.16$\\pm$0.01. We find a shift in the characteristic magnitude, $M^*$, towards fainter magnitudes for void galaxies and find no significant difference between the faint-end slopes of the void and wall galaxy LFs. We investigate how low surface brightness selections effects can affect the galaxy LF. To attempt to examine a sample of galaxies that is relatively free of surface brightness selection effects, we compute the optical galaxy LF of galaxies detected by ...

  1. The Galaxy Luminosity Function at z~1 in the HUDF: Probing the Dwarf Population

    CERN Document Server

    Ryan, R E; Cohen, S H; Malhotra, S; Rhoads, J; Windhorst, R A; Budavari, T; Pirzkal, N; Xu, C; Panagia, N; Moustakas, L; Alighieri, S di Serego; Yan, H

    2007-01-01

    We present a catalog of spectro-photometric redshifts for 1308 galaxies from the GRism ACS Program for Extragalactic Science (GRAPES) observations with the Hubble Space Telescope. These low-resolution spectra between 6000 A and 9500 A are supplemented with U, J, H, and Ks from various facilities, resulting in redshifts computed with ~40 spectral bins per galaxy. For 81 galaxies between 0.5luminosity function in this redshift range from 72 galaxies. Owing to the depth of the GRAPES survey, we are able to accurately constrain the faint-end slope by going to M_B~-18 mag at 0.8

  2. A turn-over in the galaxy luminosity function of the coma cluster core?

    CERN Document Server

    Adami, C; Durret, F; Nichol, R C; Mazure, A; Holden, B P; Romer, A K; Savine, C

    2000-01-01

    Our previous study of the faint end (R$\\leq$21.5) of the galaxy luminosity function (GLF) was based on spectroscopic data in a small region near the Coma cluster center. In this previous study Adami et al. (1998) suggested, with moderate statistical significance, that the number of galaxies actually belonging to the cluster was much smaller than expected. This led us to increase our spectroscopic sample. Here, we have improved the statistical significance of the results of the Coma GLF faint end study (R$\\leq$22.5) by using a sample of 85 redshifts. This includes both new spectroscopic data and a literature compilation. The relatively small number of faint galaxies belonging to Coma that was suggested by Adami et al. (1998) and Secker et al. (1998) has been confirmed with these new observations. We also confirm that the color-magnitude relation is not well suited for finding the galaxies inside the Coma cluster core, close to the center at magnitudes fainter than R$\\sim$19. We show that there is an enhancemen...

  3. Star formation in high redshift galaxies including Supernova feedback: effect on stellar mass and luminosity functions

    CERN Document Server

    Samui, Saumyadip

    2014-01-01

    We present a semi-analytical model of high redshift galaxy formation. In our model the star formation inside a galaxy is regulated by the feedback from supernova (SNe) driven outflows. We derive a closed analytical form for star formation rate in a single galaxy taking account of the SNe feedback in a self-consistent manner. We show that our model can explain the observed correlation between the stellar mass and the circular velocity of galaxies from dwarf galaxies to massive galaxies of $10^{12} M_\\odot$. For small mass dwarf galaxies additional feedback other than supernova feedback is needed to explain the spread in the observational data. Our models reproduce the observed 3-D fundamental correlation between the stellar mass, gas phase metallicity and star formation rate in galaxies establishing that the SNe feedback plays a major role in building this relation. Further, the observed UV luminosity functions of Lyman-Break galaxies (LBGs) are well explained by our feedback induced star formation model for a...

  4. High Frequency Cluster Radio Galaxies: Luminosity Functions and Implications for SZE Selected Cluster Samples

    CERN Document Server

    Gupta, N; Mohr, J J; Benson, B A; Bocquet, S; Carlstrom, J E; Capasso, R; Chiu, I; Crawford, T M; de Haan, T; Dietrich, J P; Gangkofner, C; Holzapfel, W L; McDonald, M; Rapetti, D; Reichardt, C L

    2016-01-01

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the Meta-Catalog of X-ray detected Clusters of galaxies (MCXC; $\\langle z \\rangle = 0.14$) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg$^2$ SPT-SZ survey maps at the locations of SUMSS sources, producing a multi-frequency catalog of radio galaxies. In the direction of massive galaxy clusters, the radio galaxy flux densities at 95 and 150 GHz are biased low by the cluster Sunyaev-Zel'dovich Effect (SZE) signal, which is negative at these frequencies. We employ a cluster SZE model to remove the expected flux bias and then study these corrected source catalogs. We find that the high frequency radio galaxies are centrally concentrated within the clusters and that their luminosity functions (LFs) exhibit amplitudes that are characteristically an order of magnitude lower than the cluster LF at 843 MHz. ...

  5. On the faint-end of the high-$z$ galaxy luminosity function

    CERN Document Server

    Yue, Bin; Xu, Yidong

    2016-01-01

    Recent measurement of the Luminosity Function (LF) of galaxies in the Epoch of Reionization (EoR, redshift $z>6$) indicates a very steep increase of the number density of low-mass galaxies populating the LF faint-end. As star formation in such systems can be easily quenched by radiative feedback effects, a turn-off is expected at some faint magnitude. Using a physically-motivated analytical model, we quantify reionization feedback effects on the LF. If reionization feedback is neglected, the power-law Schechter parameterization characterizing the faint-end of the LF remains valid up to $M_{\\rm UV}\\sim -9$. If (strong) feedback is included, the LF drops above $M_{\\rm UV} \\sim -15$, slightly below the detection limit of current surveys at $z\\sim5$. However, the LF may rise again at higher $M_{\\rm UV}$ as a result of the interplay between reionization topology and photo-evaporation physics. Moreover, we find that the stellar age -- magnitude relation might be used as a probe of feedback strength as well: in mode...

  6. Hidden Photon Compton and Bremsstrahlung in White Dwarf Anomalous Cooling and Luminosity Functions

    CERN Document Server

    Chang, Chia-Feng

    2016-01-01

    We computed the contribution of the Compton and Bremsstrahlung processes with a hidden light $U(1)_D$ neutral boson $\\gamma_D$ to the white dwarf G117-B15A anomalous cooling rate, as well as the white dwarf luminosity functions (WDLF). We demonstrated that for a light mass of hidden photon ($m_{\\gamma_D} \\ll$ a few keV), compatible results are obtained for the recent Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey observation, but the stringent limits would be imposed on the kinetic mixing $\\epsilon$. We performed $\\chi^2$-tests to acquire a quantitative assessment on the WDLF data in the context of our model, computed under the assumption of different kinetic mixing $\\epsilon$, the age of the oldest computed stars $T_D$, and a constant star formation rate $\\psi$. Then taken together, the WDLF analysis of 2$\\sigma$ confidence interval $\\epsilon = \\left( 0.37^{+0.35}_{-0.37}\\right) \\times 10^{-14}$ is barely consistent with the cooling rate analysis at 2$\\sigma$ regime $\\epsilon = \\left( 0.97^{+0.35}_{...

  7. The Radio Luminosity Function of the NEP Distant Cluster Radio Galaxies

    CERN Document Server

    Branchesi, M; Fanti, C; Fanti, R; Perley, R

    2005-01-01

    A complete sample of 18 X-ray selected clusters of galaxies belonging to the ROSAT North Ecliptic Pole (NEP) survey has been observed with the Very Large Array at 1.4 GHz. These are the most distant clusters in the X-ray survey with redshift in the range 0.3 =0.17 mJy/beam, except for three sources, belonging to the same cluster, which have a higher peak brightness limit of 0.26 mJy/beam. The NEP field source counts are in good agreement with the source counts of a comparison survey, the VLA-VIRMOS deep field survey, indicating that the NEP sample is statistically complete. Thirty-two out of the 79 sources are within 0.2 Abell radii, twenty-two of them are considered cluster members based on spectroscopic redshifts or their optical magnitude and morphological classification. The cluster radio galaxies are used to construct the Radio Luminosity Function (RLF) of distant X-ray selected clusters. A comparison with two nearby cluster RLFs shows that the NEP RLF lies above the local ones, has a steeper slope at lo...

  8. The Luminosity Function of Young Star Clusters In "The Antennae" Galaxies (NGC 4038/4039)

    CERN Document Server

    Whitmore, B C; Leitherer, C; Fall, S M; Schweizer, F; Miller, B W; Whitmore, Bradley C.; Zhang, Qing; Leitherer, Claus; Schweizer, Francois; Miller, Bryan W.

    1999-01-01

    The WFPC2 of the HST has been used to obtain high-resolution images of NGC 4038/4039 that go roughly 3 magnitudes deeper in V than previous observations made during Cycle 2 (-14 < M_V < -6). To first order the luminosity function (LF) is a power law, with exponent \\alpha = -2.12 +/- 0.04. However, after decoupling the cluster and stellar LFs, which overlap in the range -9 < M_V < -6, we find an apparent bend in the young cluster LF at approximately M_V = -10.4. The LF has a power law exponent -2.6 +/- 0.2 in the brightward and -1.7 +/- 0.2 in the faintward. The bend corresponds to a mass ~ 10^5 M_{ødot}, only slightly lower than the characteristic mass of globular clusters in the Milky Way (~2x10^5 M_{ødot}). The star clusters of the Antennae appear slightly resolved, with median effective radii of 4 +/- 1 pc, similar to or perhaps slightly larger than those of globular clusters in our Galaxy. However, the radial extents of some of the very young clusters (ages < 10 Myr) are much larger than ...

  9. Revisiting the axion bounds from the Galactic white dwarf luminosity function

    Energy Technology Data Exchange (ETDEWEB)

    Bertolami, M.M. Miller [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748, Garching (Germany); Melendez, B.E.; Althaus, L.G. [Instituto de Astrofísica de La Plata, UNLP-CONICET, Paseo del Bosque s/n, 1900 La Plata (Argentina); Isern, J., E-mail: marcelo@MPA-Garching.MPG.DE, E-mail: brenmele@gmail.com, E-mail: althaus@fcaglp.fcaglp.unlp.edu.ar, E-mail: isern@ieec.cat [Institut de Ciéncies de l' Espai (CSIC), Facultat de Ciéncies, Campus UAB, Torre C5-parell, 08193 Bellaterra (Spain)

    2014-10-01

    It has been shown that the shape of the luminosity function of white dwarfs (WDLF) is a powerful tool to check for the possible existence of DFSZ-axions, a proposed but not yet detected type of weakly interacting particles. With the aim of deriving new constraints on the axion mass, we compute in this paper new theoretical WDLFs on the basis of WD evolving models that incorporate the feedback of axions on the thermal structure of the white dwarf. We find that the impact of the axion emission into the neutrino emission can not be neglected at high luminosities M{sub  Bol}∼< 8) and that the axion emission needs to be incorporated self-consistently into the evolution of the white dwarfs when dealing with axion masses larger than m{sub a} cos {sup 2}β∼> 5 meV (i.e. axion-electron coupling constant g{sub ae}∼> 1.4× 10{sup -13}). We went beyond previous works by including 5 different derivations of the WDLF in our analysis. Then we have performed χ{sup 2}-tests to have a quantitative measure of the agreement between the theoretical WDLFs — computed under the assumptions of different axion masses and normalization methods --- and the observed WDLFs of the Galactic disk. While all the WDLF studied in this work disfavour axion masses in the range suggested by asteroseismology m{sub a} cos {sup 2}β∼> 10 meV; g{sub ae}∼> 2.8× 10{sup -13}) lower axion masses can not be discarded from our current knowledge of the WDLF of the Galactic Disk. A larger set of completely independent derivations of the WDLF of the galactic disk as well as a detailed study of the uncertainties of the theoretical WDLFs is needed before quantitative constraints on the axion-electron coupling constant can be made.

  10. The Close AGN Reference Survey (CARS)

    Science.gov (United States)

    Rothberg, Barry; Husemann, Bernd; Busch, Gerold; Dierkes, Jens; Eckart, Andreas; Krajnovic, Davor; Scharwaechter, Julia; Tremblay, Grant R.; Urrutia, Tanya

    2015-08-01

    We present the first science results from the Close AGN Reference Survey (CARS). This program is a snapshot survey of 39 local type 1 AGN (0.01 MUSE), an optical wavelength integral field unit (IFU) with a 1'x1' field of view on the VLT. The optical 3D spectroscopy complements existing sub-mm CO(1-0) data and near-IR imaging to establish a unique dataset combining molecular and stellar masses with star formation rates, gas, stellar kinematics and AGN properties. The primary goals of CARS are to:1) investigate if the star formation efficiency and gas depletion time scales are suppressed as a consequence of AGN feedback; 2) identify AGN-driven outflows and their relation to the molecular gas reservoir of the host galaxy; 3) investigate the the balance of AGN feeding and feedback through the ratio of the gas reservoir to the AGN luminosity; and 4) provide the community with a reference survey of local AGN with a high legacy value. Future work will incorporate near-infrared IFU observations to present a complete spatially resolved picture of the interplay among AGN, star-formation, stellar populations, and the ISM.

  11. Properties of galaxies at the faint end of the Hα luminosity function at z ~ 0.62

    Science.gov (United States)

    Gómez-Guijarro, Carlos; Gallego, Jesús; Villar, Víctor; Rodríguez-Muñoz, Lucía; Clément, Benjamin; Cuby, Jean-Gabriel

    2016-07-01

    Context. Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at 0.5 Research in the Southern Hemisphere (ESO), Chile, Prog-Id 181.A-0485(A).

  12. An alma survey of submillimeter galaxies in the extended Chandra deep field-south: The agn fraction and X-ray properties of submillimeter galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. X.; Brandt, W. N.; Luo, B. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Smail, I.; Alexander, D. M.; Danielson, A. L. R.; Karim, A.; Simpson, J. M.; Swinbank, A. M. [Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE (United Kingdom); Hodge, J. A.; Walter, F. [Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Lehmer, B. D. [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Wardlow, J. L. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Xue, Y. Q. [Key Laboratory for Research in Galaxies and Cosmology, Center for Astrophysics, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Chapman, S. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Coppin, K. E. K. [Centre for Astrophysics, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Dannerbauer, H. [Universität Wien, Institute für Astrophysik, Türkenschanzstraße 17, 1180 Wien (Austria); De Breuck, C. [European Southern Observatory, Karl-Schwarzschild Straße 2, D-85748 Garching (Germany); Menten, K. M. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Van der Werf, P., E-mail: xxw131@psu.edu, E-mail: niel@astro.psu.edu [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)

    2013-12-01

    The large gas and dust reservoirs of submillimeter galaxies (SMGs) could potentially provide ample fuel to trigger an active galactic nucleus (AGN), but previous studies of the AGN fraction in SMGs have been controversial largely due to the inhomogeneity and limited angular resolution of the available submillimeter surveys. Here we set improved constraints on the AGN fraction and X-ray properties of the SMGs with Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra observations in the Extended Chandra Deep Field-South (E-CDF-S). This study is the first among similar works to have unambiguously identified the X-ray counterparts of SMGs; this is accomplished using the fully submillimeter-identified, statistically reliable SMG catalog with 99 SMGs from the ALMA LABOCA E-CDF-S Submillimeter Survey. We found 10 X-ray sources associated with SMGs (median redshift z = 2.3), of which eight were identified as AGNs using several techniques that enable cross-checking. The other two X-ray detected SMGs have levels of X-ray emission that can be plausibly explained by their star formation activity. Six of the eight SMG-AGNs are moderately/highly absorbed, with N {sub H} > 10{sup 23} cm{sup –2}. An analysis of the AGN fraction, taking into account the spatial variation of X-ray sensitivity, yields an AGN fraction of 17{sub −6}{sup +16}% for AGNs with rest-frame 0.5-8 keV absorption-corrected luminosity ≥7.8 × 10{sup 42} erg s{sup –1}; we provide estimated AGN fractions as a function of X-ray flux and luminosity. ALMA's high angular resolution also enables direct X-ray stacking at the precise positions of SMGs for the first time, and we found four potential SMG-AGNs in our stacking sample.

  13. Properties of galaxies at the faint end of the Hα luminosity function at z ~ 0.62

    Science.gov (United States)

    Gómez-Guijarro, Carlos; Gallego, Jesús; Villar, Víctor; Rodríguez-Muñoz, Lucía; Clément, Benjamin; Cuby, Jean-Gabriel

    2016-07-01

    Context. Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at 0.5 forming galaxies reveals a robust faint-end slope of the luminosity function α = - 1.46-0.08+0.16 . The derived star formation rate density at z ~ 0.62 is ρSFR = 0.036-0.008+0.012 M⊙ yr-1 Mpc-3 . The sample is mainly composed of disks, but an important contribution of compact galaxies with Sérsic indexes n ~ 2 display the highest specific star formation rates. Conclusions: The luminosity function at z ~ 0.62 from our ultra-deep data points towards a steeper α when an individual extinction correction for each object is applied. Compact galaxies are low-mass, low-luminosity, and starburst-dominated objects with a light profile in an intermediate stage from early to late types. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Chile, Prog-Id 181.A-0485(A).

  14. The average 0.5-200 keV spectrum of local active galactic nuclei and a new determination of the 2-10 keV luminosity function at z ≈ 0

    Science.gov (United States)

    Ballantyne, D. R.

    2014-01-01

    The broad-band X-ray spectra of active galactic nuclei (AGNs) contains information about the nuclear environment from Schwarzschild radii scales (where the primary power law is generated in a corona) to distances of ˜1 pc (where the distant reflector may be located). In addition, the average shape of the X-ray spectrum is an important input into X-ray background synthesis models. Here, local (z ≈ 0) AGN luminosity functions (LFs) in five energy bands are used as a low-resolution, luminosity-dependent X-ray spectrometer in order to constrain the average AGN X-ray spectrum between 0.5 and 200 keV. The 15-55 keV LF measured by Swift-BAT is assumed to be the best determination of the local LF, and then a spectral model is varied to determine the best fit to the 0.5-2 keV, 2-10 keV, 3-20 keV and 14-195 keV LFs. The spectral model consists of a Gaussian distribution of power laws with a mean photon-index and cutoff energy Ecut, as well as contributions from distant and disc reflection. The reflection strength is parametrized by varying the Fe abundance relative to solar, AFe, and requiring a specific Fe Kα equivalent width (EW). In this way, the presence of the X-ray Baldwin effect can be tested. The spectral model that best fits the four LFs has = 1.85 ± 0.15, E_{cut}=270^{+170}_{-80} keV, A_{Fe}=0.3^{+0.3}_{-0.15}. The sub-solar AFe is unlikely to be a true measure of the gas-phase metallicity, but indicates the presence of strong reflection given the assumed Fe Kα EW. Indeed, parametrizing the reflection strength with the R parameter gives R=1.7^{+1.7}_{-0.85}. There is moderate evidence for no X-ray Baldwin effect. Accretion disc reflection is included in the best-fitting model, but it is relatively weak (broad iron Kα EW BAT and RXTE. We therefore present a new determination of the local 2-10 keV LF that is consistent with all other energy bands, as well as the de-evolved 2-10 keV LF estimated from the XMM-Newton Hard Bright Survey. This new LF should be used

  15. AGN variability at hard X-rays

    OpenAIRE

    Soldi, S.; Ponti, G.; Beckmann, V.; Lubinski, P.

    2010-01-01

    We present preliminary results on the variability properties of AGN above 20 keV in order to show the potential of the INTEGRAL IBIS/ISGRI and Swift/BAT instruments for hard X-ray timing analysis of AGN. The 15-50 keV light curves of 36 AGN observed by BAT during 5 years show significantly larger variations when the blazar population is considered (average normalized excess variance = 0.25) with respect to the Seyfert one (average normalized excess variance = 0.09). The hard X-ray luminosity ...

  16. Seeking the epoch of maximum luminosity for dusty quasars

    International Nuclear Information System (INIS)

    Infrared luminosities νLν(7.8 μm) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 luminosity does not show a maximum at any redshift z < 5, reaching a plateau for z ≳ 3 with maximum luminosity νLν(7.8 μm) ≳ 1047 erg s–1; luminosity functions show one quasar Gpc–3 having νLν(7.8 μm) > 1046.6 erg s–1 for all 2 luminosity has not yet been identified at any redshift below 5. The most ultraviolet luminous quasars, defined by rest frame νLν(0.25 μm), have the largest values of the ratio νLν(0.25 μm)/νLν(7.8 μm) with a maximum ratio at z = 2.9. From these results, we conclude that the quasars most luminous in the ultraviolet have the smallest dust content and appear luminous primarily because of lessened extinction. Observed ultraviolet/infrared luminosity ratios are used to define 'obscured' quasars as those having >5 mag of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ∼ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ∼ 2.1 with a possible excess of obscured quasars at fainter luminosities.

  17. Lessons learnt from INTEGRAL AGN

    CERN Document Server

    Beckmann, V; Soldi, S; Alfonso-Garzon, J; Courvoisier, T J -L; Domingo, A; Gehrels, N; Lubinski, P; Mas-Hesse, J M; Zdziarski, A A

    2010-01-01

    The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows to test the unified scheme for AGN. We present results based on the analysis of 199 AGN. A difference between the Seyfert types is detected in slightly flatter spectra with higher cut-off energies and lower luminosities for the more absorbed/type 2 AGN. When applying a Compton reflection model, the underlying continua (photon index 1.95) appear the same in Seyfert 1 and 2, and the reflection strength is R=1 in both cases, with differences in the inclination angle only. A difference is seen in the sense that Seyfert 1 are on average twice as luminous in hard X-rays than the Seyfert 2 galaxies. The unified model for Seyfert galaxies seems to hold, showing in hard X-rays that the central engine is the same in Seyfert 1 and 2 galaxies, seen under different inclination angle and absorption. Based on our knowledge of AGN from INTEGRAL data, we briefly outline open questions and investigations to answer them. In t...

  18. The galaxy UV luminosity function at z ~ 2 - 4; new results on faint-end slope and the evolution of luminosity density

    CERN Document Server

    Parsa, Shaghayegh; McLure, Ross J; Mortlock, Alice

    2015-01-01

    We present a new, robust measurement of the evolving rest-frame UV galaxy luminosity function (LF) over the key redshift range z = 2 - 4. Our results are based on the high dynamic range provided by combining the HUDF, CANDELS/GOODS-South, and UltraVISTA/COSMOS surveys. We utilise the unparalleled multi-frequency photometry available in this survey `wedding cake' to compile complete galaxy samples at z ~ 2,3,4 via photometric redshifts (calibrated against the latest spectroscopy) rather than colour-colour selection, and to determine accurate rest-frame UV absolute magnitudes from SED fitting. Our new determinations of the UV LF extend from M_{1500} ~ -22 down to M_{1500} = -14.5, -15.5 and -16 at z ~ 2, 3 and 4 respectively (thus reaching ~ 3 - 4 magnitudes fainter than previous blank-field studies at z ~ 2 - 3). At z ~ 2 - 3 we find a much shallower faint-end slope (alpha = -1.32 +- 0.03) than the steeper values (alpha ~ -1.7) reported by Reddy & Steidel (2009) or by Alavi et al. (2014), and show that thi...

  19. The Properties of Poor Groups of Galaxies. III. The Galaxy Luminosity Function

    Science.gov (United States)

    Zabludoff, Ann I.; Mulchaey, John S.

    2000-08-01

    The form of the galaxy luminosity function (GLF) in poor groups-regions of intermediate galaxy density that are common environments for galaxies-is not well understood. Multiobject spectroscopy and wide-field CCD imaging now allow us to measure the GLF of bound group members directly (i.e., without statistical background subtraction) and to compare the group GLF with the GLFs of the field and of rich clusters. We use R-band images in 1.5×1.5 degree2 mosaics to obtain photometry for galaxies in the fields of six nearby (2800composite group GLF for group members with -23+5logh=MR>-19+5logh) to giants (MRcomposite GLF for the luminous X-ray groups is consistent in shape with two measures of the composite R-band GLF for rich clusters (Trentham; Driver et al.) and flatter at the faint end than another (α~-1.5 Smith et al.); (3) the composite group GLF rises more steeply at the faint end than the R-band GLF of the Las Campanas Redshift Survey (LCRS; α=-0.7 from Lin et al.), a large volume survey dominated by galaxies in environments more rarefied than luminous X-ray groups; (4) the shape difference between the LCRS field and composite group GLFs results mostly from the population of non-emission line galaxies (EW [O II]line dwarfs are more concentrated about the group center than the non-emission line giants, except for the central, brightest (MRdark matter. This trend conflicts with the prediction of standard biased galaxy formation models.

  20. DEEP ULTRAVIOLET LUMINOSITY FUNCTIONS AT THE INFALL REGION OF THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest ultraviolet (UV) luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to MUV = –10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes (α ≈ –1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parameterization of the UV LFs resulting in a faint-end slope of α ≈ –1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than α = –1 (a turnover) for the LFs constructed separately for passive and star-forming galaxies. The UV LFs for star-forming galaxies show a turnover at MUV ≈ –14 owing to a deficit of dwarf star-forming galaxies in Coma with stellar masses below M* = 108 M☉. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star-forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star-forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star-forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.

  1. Deep UV Luminosity Functions at the Infall Region of the Coma Cluster

    Science.gov (United States)

    Hammer, D. M.; Hornschemeier, A. E.; Salim, S.; Smith, R.; Jenkins, L.; Mobasher, B.; Miller, N.; Ferguson, H.

    2011-01-01

    We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest UV luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to M(sub uv) = -10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes (alpha approximately equal to -1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parametrization of the UV LFs resulting in a faint-end slope of alpha approximately equal to -1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than alpha = -1 (a turnover) for the LFs constructed separately for passive and star forming galaxies. The UV LFs for star forming galaxies show a turnover at M(sub UV) approximately equal to -14 owing to a deficit of dwarf star forming galaxies in Coma with stellar masses below M(sub *) = 10(sup 8) solar mass. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.

  2. Hard X-ray luminosity function of tidal disruption events: First results from the MAXI extragalactic survey

    Science.gov (United States)

    Kawamuro, Taiki; Ueda, Yoshihiro; Shidatsu, Megumi; Hori, Takafumi; Kawai, Nobuyuki; Negoro, Hitoshi; Mihara, Tatehiro

    2016-08-01

    We derive the first hard X-ray luminosity function (XLF) of stellar tidal disruption events (TDEs) by supermassive black holes (SMBHs), which gives an occurrence rate of TDEs per unit volume as a function of peak luminosity and redshift, utilizing an unbiased sample observed by the Monitor of All-sky X-ray Image (MAXI). On the basis of the light curves characterized by a power-law decay with an index of -5/3, a systematic search using the MAXI data detected four TDEs in the first 37 months of observations, all of which have been found in the literature. To formulate the TDE XLF, we consider the mass function of SMBHs, that of disrupted stars, the specific TDE rate as a function of SMBH mass, and the fraction of TDEs with relativistic jets. We perform an unbinned maximum likelihood fit to the MAXI TDE list and check the consistency with the observed TDE rate in the ROSAT all-sky survey. The results suggest that the intrinsic fraction of the jet-accompanying events is 0.0007%-34%. We confirm that at z ≲ 1.5 the contamination of the hard X-ray luminosity functions of active galactic nuclei by TDEs is not significant and hence that their contribution to the growth of SMBHs is negligible at the redshifts.

  3. The Herschel PEP/HerMES Luminosity Function. I: Probing the Evolution of PACS selected Galaxies to z~4

    CERN Document Server

    Gruppioni, C; Rodighiero, G; Delvecchio, I; Berta, S; Pozzetti, L; Zamorani, G; Andreani, P; Cimatti, A; Ilbert, O; Floch, E Le; Lutz, D; Magnelli, B; Marchetti, L; Monaco, P; Nordon, R; Oliver, S; Popesso, P; Riguccini, L; Roseboom, I; Rosario, D J; Sargent, M; Vaccari, M; Altieri, B; Aussel, H; Bongiovanni, A; Cepa, J; Daddi, E; Dominguez-Sanchez, H; Elbaz, D; Forster-Schreiber, N; Genzel, R; Iribarrem, A; Magliocchetti, M; Maiolino, R; Poglitsch, A; Garcia, A Perez; Sanchez-Portal, M; Sturm, E; Tacconi, L; Valtchanov, I; Amblard, A; Arumugam, V; Bethermin, M; Bock, J; Boselli, A; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Cooray, A; Dowell, C D; Dwek, E; Eales, S; Franceschini, A; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Nguyen, H T; Halloran, B O; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rigopoulou, D; Rowan-Robinson, M; Schulz, B; Scott, D; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Vigroux, L; Wang, L; Wright, G; Xu, C K; Zemcov, M; Bardelli, S; Carollo, M; Contini, T; Fevre, O Le; Lilly, S; Mainieri, V; Renzini, A; Scodeggio, M; Zucca, E

    2013-01-01

    We exploit the deep and extended far infrared data sets (at 70, 100 and 160 um) of the Herschel GTO PACS Evolutionary Probe (PEP) Survey, in combination with the HERschel Multi tiered Extragalactic Survey (HerMES) data at 250, 350 and 500 um, to derive the evolution of the restframe 35 um, 60 um, 90 um, and total infrared (IR) luminosity functions (LFs) up to z~4. We detect very strong luminosity evolution for the total IR LF combined with a density evolution. In agreement with previous findings, the IR luminosity density increases steeply to z~1, then flattens between z~1 and z~3 to decrease at z greater than 3. Galaxies with different SEDs, masses and sSFRs evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to the IR luminosity density. Galaxies occupying the well established SFR/stellar mass main sequence (MS) are found to dominate both the total IR LF a...

  4. HerMES: Unveiling obscured star formation - the far infrared luminosity function of ultraviolet-selected galaxies at z~1.5

    CERN Document Server

    Heinis, S; Béthermin, M; Aussel, H; Bock, J; Boselli, A; Burgarella, D; Conley, A; Cooray, A; Farrah, D; Ibar, E; Ilbert, O; Ivison, R J; Magdis, G; Marsden, G; Oliver, S J; Page, M J; Rodighiero, G; Roehlly, Y; Schulz, B; Scott, Douglas; Smith, A J; Viero, M; Wang, L; Zemcov, M

    2012-01-01

    We study the far-infrared (IR) and sub-millimeter properties of a sample of ultraviolet (UV) selected galaxies at z\\sim1.5. Using stacking at 250, 350 and 500 um from Herschel Space Observatory SPIRE imaging of the COSMOS field obtained within the HerMES key program, we derive the mean IR luminosity as a function of both UV luminosity and slope of the UV continuum beta. The IR to UV luminosity ratio is roughly constant over most of the UV luminosity range we explore. We also find that the IR to UV luminosity ratio is correlated with beta. We observe a correlation that underestimates the correlation derived from low-redshift starburst galaxies, but is in good agreement with the correlation derived from local normal star-forming galaxies. Using these results we reconstruct the IR luminosity function of our UV-selected sample. This luminosity function recovers the IR luminosity functions measured from IR selected samples at the faintest luminosities (Lir ~ 10^{11} L_sun), but might underestimate them at the brig...

  5. Compton Thick AGN in the 70 Month Swift-BAT All-Sky Hard X-ray Survey: a Bayesian approach

    CERN Document Server

    Akylas, A; Ranalli, P; Gkiokas, E; Corral, A; Lanzuisi, G

    2016-01-01

    The 70-month Swift/BAT catalogue provides a sensitive view of the extragalactic X-ray sky at hard energies (>10 keV) containing about 800 Active Galactic Nuclei. We explore its content in heavily obscured, Compton-thick AGN by combining the BAT (14-195 keV) with the lower energy XRT (0.3-10 keV) data. We apply a Bayesian methodology using Markov chains to estimate the exact probability distribution of the column density for each source. We find 54 possible Compton-thick sources (with probability 3 to 100%) translating to a ~7% fraction of the AGN in our sample. We derive the first parametric luminosity function of Compton-thick AGN. The unabsorbed luminosity function can be represented by a double power-law with a break at $L_{\\star} 2 \\times 10^{42}$ $\\rm ergs~s^{-1}$ in the 20-40 keV band.

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

    Science.gov (United States)

    Finkelstein, Steven L.; Ryan, Russell E., Jr.; Papovich, Casey; Dickinson, Mark; Song, Mimi; Somerville, Rachel; Ferguson, Henry C.; Salmon, Brett; Giavalisco, Mauro; Koekomoer, Anton M.; Ashby, Matthew L. N.; Behroozi, Peter; Castellano, Marco; Dunlop, James S.; Faber, Sandy M.; Fazio, Giovanni G.; Fontana, Adriano; Grogin, Norman A.; Hathi, Nimish; Jaacks, Jason; Kocevski, Dale D.; Livermore, Rachael; McLure, Ross J.; Merlin, Emiliano; Rafelski, Marc Alexander

    2014-01-01

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

  7. AGN variability time scales and the discrete-event model

    OpenAIRE

    Favre, P; Courvoisier, T. J. -L.; Paltani, S.

    2005-01-01

    We analyse the ultraviolet variability time scales in a sample of 15 Type 1 Active Galactic Nuclei (AGN) observed by IUE. Using a structure function analysis, we demonstrate the existence in most objects of a maximum variability time scale of the order of 0.02-1.00 year. We do not find any significant dependence of these maximum variability time scales on the wavelength, but we observe a weak correlation with the average luminosity of the objects. We also observe in several objects the existe...

  8. The local luminosity function of star-forming galaxies derived from the Planck Early Release Compact Source Catalogue

    CERN Document Server

    Negrello, Mattia; Gonzalez-Nuevo, Joaquin; De Zotti, Gianfranco; Bonavera, Laura; Cosco, Giorgio; Guarese, Gianpaolo; Boaretto, Luca; Serjeant, Stephen; Toffolatti, Luigi; Lapi, Andrea; Bethermin, Matthieu; Castex, Guillaume; Clements, Dave L; Delabrouille, Jacques; Dole, Herve'; Franceschini, Alberto; Mandolesi, Reno; Marchetti, Lucia; Partridge, Bruce; Sajina, Anna

    2012-01-01

    The Planck Early Release Compact Source Catalog (ERCSC) has offered the first opportunity to accurately determine the luminosity function of dusty galaxies in the very local Universe (i.e. distances ~ L_star our results agree with previous estimates, derived from the SCUBA Local Universe Galaxy Survey (SLUGS), but are higher than the latter at L <~ L_star. We also find good agreement with estimates at 350 and 500 microns based on preliminary Herschel survey data.

  9. AGN feedback in elliptical galaxies: numerical simulations

    CERN Document Server

    Ciotti, L

    2011-01-01

    The importance of feedback (radiative and mechanical) from massive black holes at the centers of elliptical galaxies is not in doubt, given the well established relation among black hole mass and galaxy optical luminosity. Here, with the aid of high-resolution hydrodynamical simulations, we discuss how this feedback affects the hot ISM of isolated elliptical galaxies of different mass. The cooling and heating functions include photoionization plus Compton heating, the radiative transport equations are solved, and the mechanical feedback due to the nuclear wind is also described on a physical basis; star formation is considered. In the medium-high mass galaxies the resulting evolution is highly unsteady. At early times major accretion episodes caused by cooling flows in the recycled gas produced by stellar evolution trigger AGN flaring: relaxation instabilities occur so that duty cycles are small enough to account for the very small fraction of massive ellipticals observed to be in the QSO-phase, when the accr...

  10. Mid-Infrared Luminosity Function of Local Star-Forming Galaxies in the NEP-Wide Survey Field of AKARI

    CERN Document Server

    Kim, Seong Jin; Jeong, Woong-Seob; Goto, Tomotsugu; Matsuhara, Hideo; Im, Myungshin; Shim, Hyunjin; Kim, Min Gyu; Lee, Myung Gyoon

    2015-01-01

    We present mid-infrared (MIR) luminosity functions (LFs) of local star-forming (SF) galaxies in the AKARI NEP-Wide Survey field. In order to derive more accurate luminosity function, we used spectroscopic sample only. Based on the NEP-Wide point source catalogue containing a large number of infrared (IR) sources distributed over the wide (5.4 sq. deg.) field, we incorporated the spectroscopic redshift data for about 1790 selected targets obtained by optical follow-up surveys with MMT/Hectospec and WIYN/Hydra. The AKARI continuous 2 to 24 micron wavelength coverage as well as photometric data from optical u band to NIR H-band with the spectroscopic redshifts for our sample galaxies enable us to derive accurate spectral energy distributions (SEDs) in the mid-infrared. We carried out SED fit analysis and employed 1/Vmax method to derive the MIR (8, 12, and 15 micron rest-frame) luminosity functions. We fit our 8 micron LFs to the double power-law with the power index of alpha= 1.53 and beta= 2.85 at the break lu...

  11. The 0.1luminosity function

    CERN Document Server

    Comparat, Johan; Kneib, Jean-Paul; Ilbert, Olivier; Gonzalez-Perez, V; Tresse, Laurence; Zoubian, Julien; Arnouts, Stephane; Bacon, Roland; Brownstein, Joel R; Baugh, Carlton; Delubac, Timothee; Ealet, Anne; Escoffier, Stephanie; Ge, Jian; Jullo, Eric; Lacey, Cedric; Ross, Nicholas P; Schlegel, David; Schneider, Donald P; Steele, Oliver; Tasca, Lidia; Yeche, Christophe; Lesser, Michael; Jiang, Zhaoji; Jing, Yipeng; Fan, Zhou; Fan, Xiaohui; Ma, Jun; Nie, Jundan; Wang, Jiali; Wu, Zhenyu; Zhang, Tianmeng; Zhou, Xu; Zhou, Zhimin; Zou, Hu

    2014-01-01

    We present the [OII] luminosity function measured in the redshift range 0.1luminosity function. The measured luminosity function is in good agreement with previous independent estimates. The comparison with two state-of-the-art semi-analytical models is very good up to z= 1.1, which is encouraging for the production of mock catalogs of [OII] flux limited surveys. We observe the bright end evolution over 8.5 Gyr: we measure the decrease of log L* from 42.4 erg/s at redshift...

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

    CERN Document Server

    Finkelstein, Steven L; Papovich, Casey; Dickinson, Mark; Song, Mimi; Somerville, Rachel; Ferguson, Henry C; Salmon, Brett; Giavalisco, Mauro; Koekemoer, Anton M; Ashby, Matthew L N; Behroozi, Peter; Castellano, Marco; Dunlop, James S; Faber, Sandy M; Fazio, Giovanni G; Fontana, Adriano; Grogin, Norman A; Hathi, Nimish; Jaacks, Jason; Kocevski, Dale D; Livermore, Rachael; McLure, Ross J; Merlin, Emiliano; Mobasher, Bahram; Newman, Jeffrey A; Rafelski, Marc; Tilvi, Vithal; Willner, S P

    2014-01-01

    We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity function at z=4-8. We use deep Hubble Space Telescope imaging over the CANDELS/GOODS fields, the Hubble Ultra Deep Field and the Year 1 Hubble Frontier Field deep parallel observations. These surveys provides an effective volume of 0.6-1.2 x 10^6 Mpc^3 over this epoch, allowing us to perform a robust search for bright (M_UV 1000 galaxies at z~6-8. We measure the luminosity function using a Markov Chain Monte Carlo analysis to measure robust uncertainties. At the faint end our results agree with previous studies, yet we find a higher abundance of UV-bright galaxies at z>6, with M* ~ -21 at z>5, different than that inferred based on previous trends at lower redshift. At z=8, a single power-law provides an equally good fit to the UV luminosity function, while at z=6 and 7, an exponential cutoff at the bright-end is moderately preferred. We compare to semi-analytical models, and find that the lack of evolution in M* is cons...

  13. Evidence for evolution of the luminosity function of clusters of galaxies

    Science.gov (United States)

    Edge, Alastair C.; Stewart, G. C.; Fabian, A. C.; Arnaud, K. A.

    1991-01-01

    From an all sky, x-ray flux limited sample of clusters of galaxies evidence for a significant deficit in the number of high luminosity clusters is found in the redshift range z approximately 0.1 to 0.2 compared with numbers of nearby clusters. This indicates that the x-ray luminous clusters are undergoing strong evolution. The strength of the effect is consistent with hierarchical merging models. The implications of such strong evolution for clusters are discussed.

  14. The Radius-Luminosity Relationship for Active Galactic Nuclei

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.; Vestergaard, Marianne; Onken, Christopher A.

    2006-01-01

    We have obtained high resolution images of the central regions of 14 reverberation-mapped active galactic nuclei (AGN) using the Hubble Space Telescope Advanced Camera for Surveys High Resolution Camera to account for host-galaxy starlight contamination of measured AGN luminosities. We measure the...

  15. The SEDs, Host Galaxies and Environments of Variability Selected AGN in GOODS-S

    OpenAIRE

    Villforth, Carolin; Sarajedini, Vicki; Koekemoer, Anton

    2012-01-01

    Variability selection has been proposed as a powerful tool for identifying both low-luminosity AGN and those with unusual SEDs. However, a systematic study of sources selected in such a way has been lacking. In this paper, we present the multi-wavelength properties of the variability selected AGN in GOODS South. We demonstrate that variability selection indeed reliably identifies AGN, predominantly of low luminosity. We find contamination from stars as well as a very small sample of sources t...

  16. The space density of Compton-thick AGN at z~0.8 in the zCOSMOS-Bright Survey

    CERN Document Server

    Vignali, C; Gilli, R; Comastri, A; Iwasawa, K; Zamorani, G; Mainieri, V; Bongiorno, A

    2014-01-01

    The obscured accretion phase in BH growth is a key ingredient in many models linking the AGN activity with the evolution of their host galaxy. At present, a complete census of obscured AGN is still missing. The purpose of this work is to assess the reliability of the [NeV] emission line at 3426 A to pick up obscured AGN up to z~1 by assuming that [NeV] is a reliable proxy of the intrinsic AGN luminosity and using moderately deep X-ray data to characterize the amount of obscuration. A sample of 69 narrow-line (Type 2) AGN at z=0.65-1.20 were selected from the 20k-zCOSMOS Bright galaxy sample on the basis of the presence of the [NeV] emission. The X-ray properties of these galaxies were then derived using the Chandra-COSMOS coverage of the field; the X-ray-to-[NeV] flux ratio, coupled with X-ray spectral and stacking analyses, was then used to infer whether Compton-thin or Compton-thick absorption were present in these sources. Then the [NeV] luminosity function was computed to estimate the space density of Com...

  17. Mid- and far-infrared luminosity functions and galaxy evolution from multiwavelength Spitzer observations up to z ~ 2.5

    Science.gov (United States)

    Rodighiero, G.; Vaccari, M.; Franceschini, A.; Tresse, L.; Le Fevre, O.; Le Brun, V.; Mancini, C.; Matute, I.; Cimatti, A.; Marchetti, L.; Ilbert, O.; Arnouts, S.; Bolzonella, M.; Zucca, E.; Bardelli, S.; Lonsdale, C. J.; Shupe, D.; Surace, J.; Rowan-Robinson, M.; Garilli, B.; Zamorani, G.; Pozzetti, L.; Bondi, M.; de la Torre, S.; Vergani, D.; Santini, P.; Grazian, A.; Fontana, A.

    2010-06-01

    Context. Studies of the infrared (IR) emission of cosmic sources have proven essential to constraining the evolutionary history of cosmic star formation and the gravitational accretion of nuclear black holes, because many of these events occur inside heavily dust-extinguished environments. Aims: The Spitzer Space Telescope has provided a large amount of data to constrain the nature and cosmological evolution of infrared source populations. In the present paper we exploit a large homogeneous dataset to derive a self-consistent picture of IR emission based on the time-dependent λ_eff = 24, 15, 12, and 8 μm monochromatic and bolometric IR luminosity functions (LF) over the full 0 1.5. Based on the multiwavelength information available in these areas, we constrain the LFs at 8, 12, 15, and 24 μm. We also infer the total IR luminosities from our best-fit model of the observed SEDs of each source, and use this to derive the bolometric (8-1000 μm) LF and comoving volume emissivity to z ~ 2.5. Results: In the redshift interval 0 1. The mean redshift of the peak in the source number density shifts with luminosity: the brightest IR galaxies appear to form stars at earlier cosmic times (z > 1.5), while star formation in the less luminous galaxies continues until more recent epochs (z ~ 1 for LIR 1. We also appear to measure a difference in the evolutionary rate of the source number densities as a function of luminosity, which is consistent with the downsizing evolutionary patterns reported for other samples of cosmic sources.

  18. 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⊙.

  19. Narrow-line region gas kinematics of 24,264 optically-selected AGN: the radio connection

    CERN Document Server

    Mullaney, J R; Fine, S; Goulding, A D; Harrison, C M; Hickox, R C

    2013-01-01

    Using a sample of 24264 optically selected AGNs from the SDSS DR7 database, we characterise how the profile of the [OIII] emission line relates to bolometric luminosity (L_Bol), Eddington ratio, radio loudness, radio luminosity (L_Rad) and optical class (Sy 1/2) to determine what drives the kinematics of this kpc-scale line emitting gas. Spectral stacking is used to characterise how the average [OIII] profile changes as a function of these variables. After accounting for the correlation between L_Bol and L_Rad, we report that L_Rad has the strongest influence on the [OIII] profile, with moderate radio luminosity AGNs (log(L_Rad)=23-25 W/Hz) having the broadest [OIII] profiles. When binned according to Eddington ratio, only AGNs in our highest bin (i.e., R_Edd>0.3) show any signs of having broadened [OIII] profiles, although the small numbers of such extreme AGNs mean we cannot rule out that other processes (e.g., radio jets) are responsible for this broadening. We find no significant difference between the [O...

  20. Time Series Analysis of the UV Flickering in AGN

    Science.gov (United States)

    Robinson, Edward L.

    2003-01-01

    Goals of the Research: Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability.

  1. A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

    Science.gov (United States)

    Menzel, M.-L.; Merloni, A.; Georgakakis, A.; Salvato, M.; Aubourg, E.; Brandt, W. N.; Brusa, M.; Buchner, J.; Dwelly, T.; Nandra, K.; Pâris, I.; Petitjean, P.; Schwope, A.

    2016-03-01

    This paper presents a survey of X-ray-selected active galactic nuclei (AGNs) with optical spectroscopic follow-up in a ˜ 18 deg2 area of the equatorial XMM-XXL north field. A sample of 8445 point-like X-ray sources detected by XMM-Newton above a limiting flux of F_{0.5-10 keV} > 10^{-15} erg cm^{-2} s^{-1} was matched to optical (Sloan Digital Sky Survey, SDSS) and infrared (IR; WISE) counterparts. We followed up 3042 sources brighter than r = 22.5 mag with the SDSS Baryon Oscillation Spectroscopic Survey (BOSS) spectrograph. The spectra yielded a reliable redshift measurement for 2578 AGNs in the redshift range z = 0.02-5.0, with 0.5-2 keV luminosities ranging from 1039-1046 erg s- 1. This is currently the largest published spectroscopic sample of X-ray-selected AGNs in a contiguous area. The BOSS spectra of AGN candidates show a distribution of optical line widths which is clearly bimodal, allowing an efficient separation between broad- and narrow-emission line AGNs. The former dominate our sample (70 per cent) due to the relatively bright X-ray flux limit and the optical BOSS magnitude limit. We classify the narrow-emission line objects (22 per cent of the full sample) using standard optical emission line diagnostics: the majority have line ratios indicating the dominant source of ionization is the AGN. A small number (8 per cent of the full sample) exhibit the typical narrow line ratios of star-forming galaxies, or only have absorption lines in their spectra. We term the latter two classes `elusive' AGN, which would not be easy to identify correctly without their X-ray emission. We also compare X-ray (XMM-Newton), optical colour (SDSS) and and IR (WISE) AGN selections in this field. X-ray observations reveal, by far, the largest number of AGN. The overlap between the selections, which is a strong function of the imaging depth in a given band, is also remarkably small. We show using spectral stacking that a large fraction of the X-ray AGNs would not be

  2. A complete view of galaxy evolution: panchromatic luminosity functions and the generation of metals

    CERN Document Server

    Blain, Andrew W; Bertoldi, Frank; Bock, James; Bradford, Matt; Dowell, C Darren; Glenn, Jason; Goldsmith, Paul; Harwit, Martin; Helou, George; Smith, J D; Soifer, B T; Stacey, Gordon; Vieira, Joaquin; Yun, Min; Zmuidzinas, Jonas

    2009-01-01

    When and how did galaxies form and their metals accumulate? Over the last decade, this has moved from an archeological question to a live investigation: there is now a broad picture of the evolution of galaxies in dark matter halos: their masses, stars, metals and supermassive blackholes. Galaxies have been found and studied in which these formation processes are taking place most vigorously, all the way back in cosmic time to when the intergalactic medium (IGM) was still largely neutral. However, the details of how and why the interstellar medium (ISM) in distant galaxies cools, is processed, recycled and enriched in metals by stars, and fuels active galactic nuclei (AGNs) remain uncertain. In particular, the cooling of gas to fuel star formation, and the chemistry and physics of the most intensely active regions is hidden from view at optical wavelengths, but can be seen and diagnosed at mid- & far-infrared (IR) wavelengths. Rest-frame IR observations are important first to identify the most luminous, i...

  3. The X-ray luminosity function of M37 and the evolution of coronal activity in low-mass stars

    CERN Document Server

    Núñez, Alejandro

    2016-01-01

    We use a 440.5 ks Chandra observation of the $\\approx$500-Myr-old open cluster M37 to derive the X-ray luminosity functions of its $\\leq1.2$ $M_{\\odot}$ stars. Combining detections of 162 M37 members with upper limits for 160 non-detections, we find that its G, K, and M stars have a similar median (0.5$-$7 keV) X-ray luminosity L$_X =10^{29.0}$ erg/s, whereas the L$_X$-to-bolometric-luminosity ratio (L$_X$/L$_{bol}$) indicates that M stars are more active than G and K stars by $\\approx$1 order of magnitude at 500 Myr. To characterize the evolution of magnetic activity in low-mass stars over their first $\\approx$600 Myr, we consolidate X-ray and optical data from the literature for stars in six other open clusters: from youngest to oldest, the Orion Nebula Cluster (ONC), NGC 2547, NGC 2516, the Pleiades, NGC 6475, and the Hyades. For these, we homogenize the conversion of instrumental count rates to L$_X$ by applying the same one-temperature emission model as for M37, and obtain masses using the same empirical...

  4. Lyman Alpha Emitters at z=7 in the Subaru/XMM-Newton Deep Survey Field: Photometric Candidates and Luminosity Function

    CERN Document Server

    Ota, Kazuaki; Kashikawa, Nobunari; Shimasaku, Kazuhiro; Ouchi, Masami; Totani, Tomonori; Kobayashi, Masakazu A R; Nagashima, Masahiro; Harayama, Atsushi; Kodaka, Natsuki; Morokuma, Tomoki; Furusawa, Hisanori; Tajitsu, Akito; Hattori, Takashi

    2010-01-01

    We conducted a deep narrowband NB973 (FWHM = 200 A centered at 9755 A) survey of z=7 Lyman alpha emitters (LAEs) in the Subaru/XMM-Newton Deep Survey Field, using the fully depleted CCDs newly installed on the Subaru Telescope Suprime-Cam, which is twice more sensitive to z=7 Lyman alpha at ~ 1 micron than the previous CCDs. Reaching the depth 0.5 magnitude deeper than our previous survey in the Subaru Deep Field that led to the discovery of a z=6.96 LAE, we detected three probable z=7 LAE candidates. Even if all the candidates are real, the Lyman alpha luminosity function (LF) at z=7 shows a significant deficit from the LF at z=5.7 determined by previous surveys. The LAE number and Lyman alpha luminosity densities at z=7 is ~ 7.7-54% and ~5.5-39% of those at z=5.7 to the Lyman alpha line luminosity limit of L(Ly-alpha) >~ 9.2 x 10^{42} erg s^{-1}. This could be due to evolution of the LAE population at these epochs as a recent galaxy evolution model predicts that the LAE modestly evolves from z=5.7 to 7. How...

  5. Photometric properties and luminosity function of nearby massive early-type galaxies

    CERN Document Server

    He, Y Q; Hao, C N; Jing, Y P; Mao, S; Li, Cheng

    2013-01-01

    We perform photometric analyses for a bright early-type galaxy (ETG) sample with 2949 galaxies ($M_{\\rm r}<-22.5$ mag) in the redshift range of 0.05 to 0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that our Petrosian magnitudes, and isophotal magnitudes to 25 ${\\rm mag/arcsec^2}$ and 1% of the sky brightness are on average 0.16 mag, 0.2 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. We find the overestimations are more strongly influenced by galaxy sizes than by galaxy luminosities. Similarly, the typical half-light radii ($r_{50}$) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright-end of the $r-$band luminosity...

  6. Spectral Energy Distributions of Type 1 AGNs

    Science.gov (United States)

    Hao, Heng

    The spectral energy distributions (SEDs) of active galactic nuclei (AGNs) are essential to understand the physics of supermassive black holes (SMBHs) and their host galaxies. This thesis present a detailed study of AGN SED shapes in the optical-near infrared bands (0.3--3microm) for 413 X-ray selected Type 1 AGNs from the XMM-COSMOS Survey. We define a useful near-IR/optical index-index ('color-color') diagram to investigate the mixture of AGN continuum, host galaxy and reddening contributions. We found that ˜90% of the AGNs lie on mixing curves between the Elvis et al. (1994) mean AGN SED (E94) and a host galaxy, with only the modest reddening [E(B-V)=0.1--0.2] expected in type 1 AGNs. Lower luminosity and Eddington ratio objects have more host galaxy, as expected. The E94 template is remarkably good in describing the SED shape in the 0.3--3microrn decade of the spectrum over a range of 3.2 dex in LOPT, 2.7 dex in L/LEdd, and for redshifts up to 3. The AGN phenomenon is thus insensitive to absolute or relative accretion rate and to cosmic time. However, 10% of the AGNs are inconsistent with any AGN+host+reddening mix. These AGNs have weak or non-existent near-IR bumps, suggesting a lack of the hot dust characteristic of AGNs. The fraction of these hot-dust-poor AGNs evolves with redshift from 6% at low redshift (z times the gravitational stability radii. Either the host-dust is destroyed (dynamically or by radiation), or is offset from the central black hole due to recoiling. Alternatively, the universality of HDP quasars in samples with different selection methods and the continuous distribution of dust covering factor in type 1 AGNs, suggest that the range of SEDs could be related to the range of tilts in warped fueling disks, as in the model of Lawrence and Elvis (2010), with HDP quasars having relatively small warps. A small number of other outliers are found with the help of the mixing diagram, which could represent quasars on different evolutionary stage

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

    CERN Document Server

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

    2016-01-01

    We compare the predictions of Horizon-AGN, a hydro-dynamical cosmological simulation that uses an adaptive mesh refinement code, to observational data in the redshift range 0luminosity and stellar-mass functions, the star formation main sequence, rest-frame UV-optical-near infrared colours and the cosmic star-formation history. We show that Horizon-AGN, which is not tuned to reproduce the local Universe, produces good overall agreement with these quantities, from the present day to the epoch when the Universe was 5% of its current age. By comparison to Horizon-noAGN, a twin simulation without AGN feedback, we quantify how feedback from black holes is likely to help shape galaxy stellar-mass growth in the redshift range 0AGN successfully captures the evolutionary trends of ob...

  8. Why are there strong radio AGNs in the center of "non-cool core" clusters?

    CERN Document Server

    Sun, Ming

    2009-01-01

    Radio AGN feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in "noncool core" clusters, which brings up the question whether an X-ray cool core is always required for radio feedback. We present a systematic analysis of 152 groups and clusters to show that every BCG with a strong radio AGN has an X-ray cool core. Those strong radio AGNs in the center of the "noncool core" systems identified before are in fact associated with small X-ray cool cores with typical radii of < 5 kpc (we call them coronae). Small coronae are most likely of ISM origin and they carry enough fuel to power radio AGNs. Our results suggest that the traditional cool core/noncool core dichotomy is too simple. A better alternative is the cool core distribution function with the enclosed X-ray luminosity. Other implications of our results are also discussed, including a warning on the simple extrapolation of the de...

  9. Constraining the Warm Dark Matter Particle Mass through Ultra-Deep UV Luminosity Functions at z=2

    CERN Document Server

    Menci, N; Castellano, M; Grazian, A

    2016-01-01

    We compute the mass function of galactic dark matter halos for different values of the Warm Dark Matter (WDM) particle mass m_X and compare it with the abundance of ultra-faint galaxies derived from the deepest UV luminosity function available so far at redshift z~2. The magnitude limit M_UV=-13 reached by such observations allows us to probe the WDM mass functions down to scales close to or smaller than the half-mass mode mass scale ~10^9 M_sun. This allowed for an efficient discrimination among predictions for different m_X which turn out to be independent of the star formation efficiency adopted to associate the observed UV luminosities of galaxies to the corresponding dark matter masses. Adopting a conservative approach to take into account the existing theoretical uncertainties in the galaxy halo mass function, we derive a robust limit m_X>1.8 keV for the mass of thermal relic WDM particles when comparing with the measured abundance of the faintest galaxies, while m_X>1.5 keV is obtained when we compare ...

  10. Luminosity functions of YSO clusters in Sh-2 255, W3 Main and NGC 7538 star forming regions

    Science.gov (United States)

    Ojha, Devendra; Tamura, Motohide

    We have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the JHKs-band with the near-infrared camera SIRIUS on the UH 88-inch telescope and with SUBARU. The near-infrared surveys cover a total area of ~72 square arcmin of three regions with 10-sigma limiting magnitudes of ~19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the color-color and color-magnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538. A large number of previously unreported red sources (H-K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main sequence stars with intrinsic color excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources in or around more evolved optical HII regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters and their stellar populations are primarily composed of low mass pre-main sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age <=1 Myr).

  11. Starcounts Redivivus II: Deep Starcounts with Keck and HST and the Luminosity Function of the Galactic Halo

    OpenAIRE

    Reid, I N; Yan, Lin; S. Majewski; Thompson, I.; Smail, I. R.

    1996-01-01

    We have combined deep starcount data with Galaxy model predictions to investigate how effectively such measurements probe the faint end of the halo luminosity function. We have tested a number of star/galaxy classification techniques using images taken in 0.5 arcsecond seeing with LRIS on the Keck telescope, and we find that different combinations of these techniques can produce variations of 10 \\% in the inferred starcounts at R=22.5 and 30 \\% at R=24.5 magnitudes. The decreasing average ang...

  12. Variability Selected Low-Luminosity Active Galactic Nuclei in the 4 Ms Chandra Deep Field-South

    Science.gov (United States)

    Young, M.; Brandt, W. N.; Xue, Y. Q.; Paolillo, D. M.; Alexander, F. E.; Bauer, F. E.; Lehmer, B. D.; Luo, B.; Shemmer, O.; Schneider, D. P.; Vignail, C.

    2012-01-01

    The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X ray variability (approx. month years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts approx equals 00.8 - 1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole. The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Gamma(sub Stack) approx equals 1.93 +/- 0.13, and arc therefore likely LLAGN. The LLAGN tend to lie it factor of approx equal 6-89 below the extrapolated linear variability-luminosity relation measured for luminous AGN. This may he explained by their lower accretion rates. Variability-independent black-hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

  13. VARIABILITY-SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN THE 4 Ms CHANDRA DEEP FIELD-SOUTH

    International Nuclear Information System (INIS)

    The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGNs). However, cosmologically distant low-luminosity AGNs (LLAGNs) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (∼month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z ≈ 0.08-1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole (SMBH). The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Γstack ≈ 1.93 ± 0.13, and are therefore likely LLAGNs. The LLAGNs tend to lie a factor of ≈6-80 below the extrapolated linear variability-luminosity relation measured for luminous AGNs. This may be explained by their lower accretion rates. Variability-independent black hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

  14. The joint far-infrared-optical luminosity function for spiral galaxies and data for the Abell 400 and Cancer clusters

    International Nuclear Information System (INIS)

    Visual and IRAS data for an optically selected sample of 183 late-type galaxies are compiled in tables and graphs and analyzed in detail to determine the joint FIR-optical luminosity function Psi from the FIR/blue luminosity ratio, r = L(FIR)/L(B). It is found that Psi can be approximated by a function of a single variable psi(r-prime), where r-prime is defined as r times L(B)/L(asterisk) exp -delta, with L(asterisk) a constant and delta = about 0.08. A lognormal curve peaking at r-prime = 0.35 and with dispersion of 0.28 is shown to give a good fit to psi(r-prime). From a lack of galaxies with very low r-prime in the present sample it is inferred that there are few spiral galaxies with low interstellar-dust abundances. Also included are data on the distribution function of r-prime for the more distant clusters Abell 400 and Cancer. 29 refs

  15. The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: I. The Calibration Region

    CERN Document Server

    Covey, Kevin R; Bochanski, John J; West, Andrew A; Reid, I Neill; Golimowski, David A; Davenport, James R A; Henry, Todd; Uomoto, Alan

    2008-01-01

    We present measurements of the luminosity and mass functions of low-mass stars constructed from a catalog of matched Sloan Digital Sky Survey (SDSS) and 2 Micron All Sky Survey (2MASS) detections. This photometric catalog contains more than 25,000 matched SDSS and 2MASS point sources spanning ~30 square degrees on the sky. We have obtained follow-up spectroscopy, complete to J=16, of more than 500 low mass dwarf candidates within a 1 square degree sub-sample, and thousands of additional dwarf candidates in the remaining 29 square degrees. This spectroscopic sample verifies that the photometric sample is complete, uncontaminated, and unbiased at the 99% level globally, and at the 95% level in each color range. We use this sample to derive the luminosity and mass functions of low-mass stars over nearly a decade in mass (0.7 M_sun > M_* > 0.1 M_sun). We find that the logarithmically binned mass function is best fit with an M_c=0.29 log-normal distribution, with a 90% confidence interval of M_c=0.20--0.50. These ...

  16. Are the hosts of VLBI selected radio-AGN different to those of radio-loud AGN?

    CERN Document Server

    Rees, G A; Spitler, L R; Herrera-Ruiz, N; Middelberg, E

    2016-01-01

    Recent studies have found that radio-AGN selected by radio-loudness show little difference in terms of their host galaxy properties when compared to non-AGN galaxies of similar stellar mass and redshift. Using new 1.4~GHz VLBI observations of the COSMOS field we find that approximately 49$\\pm8$\\% of high-mass (M $>$ 10$^{10.5}$ M$_{\\odot}$), high luminosity (L$_{1.4}$ $>$ 10$^{24}$ W~Hz$^{-1}$) radio-AGN possess a VLBI detected counterpart. These objects show no discernible bias towards specific stellar masses, redshifts or host properties other than what is shown by the radio-AGN population in general. Radio-AGN that are detected in VLBI observations are not special, but form a representative sample of the radio-loud AGN population.

  17. Are the hosts of VLBI-selected radio-AGN different to those of radio-loud AGN?

    Science.gov (United States)

    Rees, G. A.; Norris, R. P.; Spitler, L. R.; Herrera-Ruiz, N.; Middelberg, E.

    2016-05-01

    Recent studies have found that radio-AGN selected by radio-loudness show little difference in terms of their host galaxy properties when compared to non-AGN galaxies of similar stellar mass and redshift. Using new 1.4 GHz very long baseline interferometry (VLBI) observations of the Cosmological Evolution Survey field, we find that approximately 49 ± 8 per cent of high-mass (M > 1010.5 M⊙), high-luminosity (L1.4 > 1024 W Hz-1) radio-AGN possess a VLBI-detected counterpart. These objects show no discernible bias towards specific stellar masses, redshifts or host properties other than what is shown by the radio-AGN population in general. Radio-AGN that are detected in VLBI observations are not special, but form a representative sample of the radio-loud AGN population.

  18. Decreased specific star formation rates in AGN host galaxies

    Science.gov (United States)

    Shimizu, T. Taro; Mushotzky, Richard F.; Meléndez, Marcio; Koss, Michael; Rosario, David J.

    2015-09-01

    We investigate the location of an ultra-hard X-ray selected sample of active galactic nuclei (AGN) from the Swift Burst Alert Telescope (BAT) catalogue with respect to the main sequence (MS) of star-forming galaxies using Herschel-based measurements of the star formation rate (SFR) and M*'s from Sloan Digital Sky Survey photometry where the AGN contribution has been carefully removed. We construct the MS with galaxies from the Herschel Reference Survey and Herschel Stripe 82 Survey using the exact same methods to measure the SFR and M* as the Swift/BAT AGN. We find that a large fraction of the Swift/BAT AGN lie below the MS indicating decreased specific SFR (sSFR) compared to non-AGN galaxies. The Swift/BAT AGN are then compared to a high-mass galaxy sample (CO Legacy Database for GALEX Arecibo SDSS Survey, COLD GASS), where we find a similarity between the AGN in COLD GASS and the Swift/BAT AGN. Both samples of AGN lie firmly between star-forming galaxies on the MS and quiescent galaxies far below the MS. However, we find no relationship between the X-ray luminosity and distance from the MS. While the morphological distribution of the BAT AGN is more similar to star-forming galaxies, the sSFR of each morphology is more similar to the COLD GASS AGN. The merger fraction in the BAT AGN is much higher than the COLD GASS AGN and star-forming galaxies and is related to distance from the MS. These results support a model in which bright AGN tend to be in high-mass star-forming galaxies in the process of quenching which eventually starves the supermassive black hole itself.

  19. AGN Winds and Blazar Phenomenology

    Science.gov (United States)

    Kazanas, Demos

    2012-01-01

    The launch of {\\em Fermi} produced a significant number of AGN detections to allow statistical treatment of their properties. One of the first such systematics was the "Blazar Divide" in FSRQs and BL Lacs according to their gamma-ray spectral index and luminosity. Further data accumulation indicated this separation to be less clear than thought before. An MHD wind model which can model successfully the Seyfert X-ray absorber properties provides the vestiges of an account of the observed blazar classification. We propose to employ this model to model in detail the broad band blazar spectra and their statistical properties in terms of the physical parameters of these MHD winds.

  20. The $z < 1.2$ optical luminosity function from a sample of $\\sim410 \\, 000$ galaxies in bootes

    CERN Document Server

    Beare, Richard A; Pimbblet, Kevin A; Bian, Fuyan; Lin, Yen-Ting

    2015-01-01

    Using a sample of ~410 000 galaxies to depth I_AB = 24 over 8.26 deg^2 in the Bootes field (~10 times larger than z~1 luminosity function studies in the prior literature), we have accurately measured the evolving B-band luminosity function of red galaxies at z<1.2 and blue galaxies at z<1.0. In addition to the large sample size, we utilise photometry that accounts for the varying angular sizes of galaxies, photometric redshifts verified with spectroscopy, and absolute magnitudes that should have very small random and systematic errors. Our results are consistent with the migration of galaxies from the blue cloud to the red sequence as they cease to form stars, and with downsizing in which more massive and luminous blue galaxies cease star formation earlier than fainter less massive ones. Comparing the observed fading of red galaxies with that to be expected from passive evolution alone, we find that the stellar mass contained within the red galaxy population has increased by a factor of ~3.6 from z~1.1 ...

  1. Radio imaging of the Subaru/XMM-Newton Deep Field - III. Evolution of the radio luminosity function beyond z=1

    CERN Document Server

    Simpson, Chris; Ivision, Rob; Akiyama, Masayuki; Almaini, Omar; Bradshaw, Emma; Chapman, Scott; Chuter, Rob; Croom, Scott; Dunlop, Jim; Foucaud, Sebastien; Hartley, Will

    2012-01-01

    We present spectroscopic and eleven-band photometric redshifts for galaxies in the 100-uJy Subaru/XMM-Newton Deep Field radio source sample. We find good agreement between our redshift distribution and that predicted by the SKA Simulated Skies project. We find no correlation between K-band magnitude and radio flux, but show that sources with 1.4-GHz flux densities below ~1mJy are fainter in the near-infrared than brighter radio sources at the same redshift, and we discuss the implications of this result for spectroscopically-incomplete samples where the K-z relation has been used to estimate redshifts. We use the infrared--radio correlation to separate our sample into radio-loud and radio-quiet objects and show that only radio-loud hosts have spectral energy distributions consistent with predominantly old stellar populations, although the fraction of objects displaying such properties is a decreasing function of radio luminosity. We calculate the 1.4-GHz radio luminosity function (RLF) in redshift bins to z=4...

  2. AGN outflows trigger starbursts in gas-rich galaxies

    CERN Document Server

    Zubovas, Kastytis; King, Andrew; Wilkinson, Mark

    2013-01-01

    Recent well resolved numerical simulations of AGN feedback have shown that its effects on the host galaxy may be not only negative but also positive. In the late gas poor phase, AGN feedback blows the gas away and terminates star formation. However, in the gas-rich phase(s), AGN outflows trigger star formation by over-compressing cold dense gas and thus provide positive feedback on their hosts. In this paper we study this AGN-triggered starburst effect. We show that star formation rate in the burst increases until the star formation feedback counteracts locally the AGN outflow compression. Globally, this predicts a strong nearly linear statistical correlation between the AGN and starburst bolometric luminosities in disc galaxies, L_* \\propto L_{AGN}^{5/6}. The correlation is statistical only because AGN activity may fluctuate on short time scales (as short as tens of years), and because AGN may turn off but its effects on the host may continue to last until the AGN-driven outflow leaves the host, which may be...

  3. On the local radio luminosity function of galaxies; 2, environmental dependences among late-type galaxies

    CERN Document Server

    Gavazzi, G

    1999-01-01

    Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS), we derive the distribution of the radio/optical and radio/NIR luminosity (RLF) of late-type (Sa-Irr) galaxies (mp<15.7) in 5 nearby clusters of galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim of discussing possible environmental dependences of the radio properties, we compare these results with those obtained for relatively isolated objects in the Coma supercluster. We find that the RLF of Cancer, A262 and Virgo are consistent with that of isolated galaxies. Conversely we confirm earlier claims that galaxies in A1367 and Coma have their radio emissivity enhanced by a factor of 5 with respect to isolated objects. We discuss this result in the framework of the dynamical pressure suffered by galaxies in motion through the intra-cluster gas (ram-pressure). We find that the radio excess is statistically larger for galaxies in fast transit motion. This is coherent with the idea that enhanced radio continuum activity is associate...

  4. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the RBLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of α= 0.533+0.035-0.033, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the RBLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  5. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Misty C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Denney, Kelly D.; Vestergaard, Marianne [Dark Cosmology Center, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Grier, Catherine J.; Peterson, Bradley M.; De Rosa, Gisella; Pogge, Richard W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li Weidong [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Gates, Elinor L. [University of California Observatories/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall - Ivy Lane, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak, E-mail: bentz@chara.gsu.edu [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

    2013-04-20

    We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  6. Far-infrared and accretion luminosities of the present-day active galactic nuclei

    CERN Document Server

    Matsuoka, Kenta

    2015-01-01

    We investigate the relation between star formation (SF) and black hole accretion luminosities, using a sample of 492 type-2 active galactic nuclei (AGNs) at z < 0.22, which are detected in the far-infrared (FIR) surveys with AKARI and Herschel. We adopt FIR luminosities at 90 and 100 um as SF luminosities, assuming the proposed linear proportionality of star formation rate with FIR luminosities. By estimating AGN luminosities from [OIII]5007 and [OI]6300 emission lines, we find a positive linear trend between FIR and AGN luminosities over a wide dynamical range. This result appears to be inconsistent with the recent reports that low-luminosity AGNs show essentially no correlation between FIR and X-ray luminosities, while the discrepancy is likely due to the Malmquist and sample selection biases. By analyzing the spectral energy distribution, we find that pure-AGN candidates, of which FIR radiation is thought to be AGN-dominated, show significantly low-SF activities. These AGNs hosted by low-SF galaxies are...

  7. Spectral decomposition of broad-line agns and host galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Vanden Berk, Daniel E.; Shen, Jiajian; /Penn State U., Astron. Astrophys.; Yip, Ching-Wa; /Pittsburgh U.; Schneider, Donald P.; /Penn State U., Astron. Astrophys.; Connolly,; /Pittsburgh U.; Burton, Ross E.; /Pittsburgh U. /Case Western Reserve U.; Jester, Sebastian; /Fermilab; Hall, Patrick B.; /York U., Canada; Szalay, Alex S.; /Johns Hopkins; Brinkmann, John; /Apache Point Observ.

    2005-09-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasingly bluer than early-type galaxies with increasing host luminosity. Most of the AGNs with detected hosts are emitting at between 1% and 10% of their estimated Eddington luminosities, but the sensitivity of the technique usually does not extend to the Eddington limit. There are mild correlations among the AGN and host galaxy eigencoefficients, possibly indicating a link between recent star formation and the onset of AGN activity. The catalog of spectral reconstruction parameters is available as an electronic table.

  8. AGN variability: from Seyfert nuclei to QSOs

    OpenAIRE

    Aretxaga, Itziar

    1996-01-01

    The continuum variability of optically selected Active Galactic Nuclei (AGN) is found to be consistent with that expected from a simple Poissonian process, in which the total luminosity of an object is produced by the multiple superposition of identical pulses. The energies, time-scales and rates of the pulses are found to be in the range of those expected from supernovae which generate fast evolving remnants in a nuclear starburst.However, radio-loud AGN don't follow the predictions of that ...

  9. THE LUMINOSITY AND MASS FUNCTIONS OF LOW-MASS STARS IN THE GALACTIC DISK. II. THE FIELD

    International Nuclear Information System (INIS)

    We report on new measurements of the luminosity function (LF) and mass function (MF) of field low-mass dwarfs derived from Sloan Digital Sky Survey Data Release 6 photometry. The analysis incorporates ∼15 million low-mass stars (0.1 Msunsun), spread over 8400 deg2. Stellar distances are estimated using new photometric parallax relations, constructed from ugriz photometry of nearby low-mass stars with trigonometric parallaxes. We use a technique that simultaneously measures Galactic structure and the stellar LF from 7 r sun o = 0.25 Msun. We stress that our results should not be extrapolated to other mass regimes. Our work generally agrees with prior low-mass stellar MFs and places strong constraints on future theoretical star formation studies.

  10. M dwarfs in the Local Milky Way: The Field Low-Mass Stellar Luminosity and Mass Functions

    Energy Technology Data Exchange (ETDEWEB)

    Bochanski, John J., Jr.; /Washington U., Seattle, Astron. Dept.

    2006-06-01

    Modern sky surveys, such as the Sloan Digital Sky Survey (SDSS) and the Two-Micron All Sky Survey, have revolutionized how Astronomy is done. With millions of photometric and spectroscopic observations, global observational properties can be studied with unprecedented statistical significance. Low-mass stars dominate the local Milky Way, with tens of millions observed by SDSS within a few kpc. Thus, they make ideal tracers of the Galactic potential, and the thin and thick disks. In this thesis dissertation, I present my efforts to characterize the local low-mass stellar population, using a collection of observations from the Sloan Digital Sky Survey (SDSS). First, low-mass stellar template spectra were constructed from the co-addition of thousands of SDSS spectroscopic observations. These template spectra were used to quantify the observable changes introduced by chromospheric activity and metallicity. Furthermore, the average ugriz colors were measured as a function of spectral type. Next, the local kinematic structure of the Milky Way was quantified, using a special set of SDSS spectroscopic observations. Combining proper motions and radial velocities (measured using the spectral templates), along with distances, the full UVW space motions of over 7000 low-mass stars along one line of sight were computed. These stars were also separated kinematically to investigate other observational differences between the thin and thick disks. Finally, this dissertation details a project designed to measure the luminosity and mass functions of low-mass stars. Using a new technique optimized for large surveys, the field luminosity function (LF) and local stellar density profile are measured simultaneously. The sample size used to estimate the LF is nearly three orders of magnitude larger than any previous study, offering a definitive measurement of this quantity. The observed LF is transformed into a mass function (MF) and compared to previous studies.

  11. Evolution of mid-infrared galaxy luminosity functions from the entire AKARI NEP-Deep field with new CFHT photometry

    CERN Document Server

    Goto, Tomotsugu; Ohyama, Youichi; Malkan, Matthew; Matsuhara, Hideo; Wada, Takehiko; Karouzos, Marios; Im, Myungshin; Nakagawa, Takao; Buat, Veronique; Burgarella, Denis; Sedgwick, Chris; Toba, Yoshiki; Jeong, Woong-Seob; Marchetti, Lucia; Małek, Katarzyna; Koptelova, Ekaterina; Chao, Dani; Wu, Yi-Han; Pearson, Chris; Takagi, Toshinobu; Lee, Hyung Mok; Serjeant, Stephen; Takeuchi, Tsutomu T; Kim, Seong Jin

    2015-01-01

    We present infrared galaxy luminosity functions (LFs) in the AKARI North Ecliptic Pole (NEP) deep field using recently-obtained, wider CFHT optical/near-IR images. AKARI has obtained deep images in the mid-infrared (IR), covering 0.6 deg$^2$ of the NEP deep field. However, our previous work was limited to the central area of 0.25 deg$^2$ due to the lack of optical coverage of the full AKARI NEP survey. To rectify the situation, we recently obtained CFHT optical and near-IR images over the entire AKARI NEP deep field. These new CFHT images are used to derive accurate photometric redshifts, allowing us to fully exploit the whole AKARI NEP deep field. AKARI's deep, continuous filter coverage in the mid-IR wavelengths (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24$\\mu$m) exists nowhere else, due to filter gaps of other space telescopes. It allows us to estimate restframe 8$\\mu$m and 12$\\mu$m luminosities without using a large extrapolation based on spectral energy distribution (SED) fitting, which was the largest uncer...

  12. A COMPLETE SAMPLE OF BRIGHT SWIFT LONG GAMMA-RAY BURSTS. I. SAMPLE PRESENTATION, LUMINOSITY FUNCTION AND EVOLUTION

    International Nuclear Information System (INIS)

    We present a carefully selected sub-sample of Swift long gamma-ray bursts (GRBs) that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches, which are bright in the 15-150 keV Swift/BAT band, i.e., with 1-s peak photon fluxes in excess to 2.6 photons s–1 cm–2. The sample is composed of 58 bursts, 52 of them with redshift for a completeness level of 90%, while another two have a redshift constraint, reaching a completeness level of 95%. For only three bursts we have no constraint on the redshift. The high level of redshift completeness allows us for the first time to constrain the GRB luminosity function and its evolution with cosmic times in an unbiased way. We find that strong evolution in luminosity (δl = 2.3 ± 0.6) or in density (δd = 1.7 ± 0.5) is required in order to account for the observations. The derived redshift distributions in the two scenarios are consistent with each other, in spite of their different intrinsic redshift distributions. This calls for other indicators to distinguish among different evolution models. Complete samples are at the base of any population studies. In future works we will use this unique sample of Swift bright GRBs to study the properties of the population of long GRBs.

  13. Galaxy And Mass Assembly (GAMA): The dependence of the galaxy luminosity function on environment, redshift and colour

    CERN Document Server

    McNaught-Roberts, Tamsyn; Baugh, Carlton; Lacey, Cedric; Loveday, J; Peacock, J; Baldry, I; Bland-Hawthorn, J; Brough, S; Driver, Simon P; Robotham, A S G; Vazquez-Mata, J A

    2014-01-01

    We use 80922 galaxies in the Galaxy And Mass Assembly (GAMA) survey to measure the galaxy luminosity function (LF) in different environments over the redshift range 0.04luminosities at which such galaxies dominate. Discrepancies between the model and the data seen in the faint end of the LF suggest too many faint red galaxies are predicted, which is likely to be due to the over-quenching of satellite galaxies. The excess of bright blue...

  14. A complete sample of bright Swift Long Gamma-Ray Bursts: Sample presentation, Luminosity Function and evolution

    CERN Document Server

    Salvaterra, R; Vergani, S D; Covino, S; D'Avanzo, P; Fugazza, D; Ghirlanda, G; Ghisellini, G; Melandri, A; Nava, L; Sbarufatti, B; Flores, H; Piranomonte, S; Tagliaferri, G

    2011-01-01

    We present a carefully selected sub-sample of Swift Long Gamma-ray Bursts (GRBs), that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches, that are bright in the 15-150 keV Swift/BAT band, i.e. with 1-s peak photon fluxes in excess to 2.6 ph s^-1 cm^-2. The sample is composed by 58 bursts, 53 of them with redshift for a completeness level of 91%, while another two have a redshift constraint, reaching a completeness level of 95%. For only three bursts we have no constraint on the redshift. The high level of redshift completeness allows us for the first time to constrain the GRB luminosity function and its evolution with cosmic times in a unbiased way. We find that strong evolution in luminosity (d_l=2.3\\pm 0.6) or in density (d_d=1.7\\pm 0.5) is required in order to account for the observations. The derived redshift distribution in the two scenarios are consistent with each other, in spite of their different intri...

  15. A COMPLETE SAMPLE OF BRIGHT SWIFT LONG GAMMA-RAY BURSTS. I. SAMPLE PRESENTATION, LUMINOSITY FUNCTION AND EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Salvaterra, R. [INAF, IASF Milano, via E. Bassini 15, I-20133 Milano (Italy); Campana, S.; Vergani, S. D.; Covino, S.; D' Avanzo, P.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Sbarufatti, B.; Tagliaferri, G. [INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Saint Lucia) (Italy); Nava, L. [SISSA, via Bonomea 265, I-34136 Trieste (Italy); Flores, H. [Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Univ. Paris-Diderot 5 place Jules Janssen, 92195 Meudon (France); Piranomonte, S., E-mail: ruben@lambrate.inaf.it [INAF, Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Rome (Italy)

    2012-04-10

    We present a carefully selected sub-sample of Swift long gamma-ray bursts (GRBs) that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches, which are bright in the 15-150 keV Swift/BAT band, i.e., with 1-s peak photon fluxes in excess to 2.6 photons s{sup -1} cm{sup -2}. The sample is composed of 58 bursts, 52 of them with redshift for a completeness level of 90%, while another two have a redshift constraint, reaching a completeness level of 95%. For only three bursts we have no constraint on the redshift. The high level of redshift completeness allows us for the first time to constrain the GRB luminosity function and its evolution with cosmic times in an unbiased way. We find that strong evolution in luminosity ({delta}{sub l} = 2.3 {+-} 0.6) or in density ({delta}{sub d} = 1.7 {+-} 0.5) is required in order to account for the observations. The derived redshift distributions in the two scenarios are consistent with each other, in spite of their different intrinsic redshift distributions. This calls for other indicators to distinguish among different evolution models. Complete samples are at the base of any population studies. In future works we will use this unique sample of Swift bright GRBs to study the properties of the population of long GRBs.

  16. The AGN content of deep radio surveys and radio emission in radio-quiet AGN. Why every astronomer should care about deep radio fields

    CERN Document Server

    Padovani, P; Miller, N; Kellermann, K I; Mainieri, V; Rosati, P; Tozzi, P; Vattakunnel, S

    2014-01-01

    We present our very recent results on the sub-mJy radio source populations at 1.4 GHz based on the Extended Chandra Deep Field South VLA survey, which reaches ~ 30 {\\mu}Jy, with details on their number counts, evolution, and luminosity functions. The sub-mJy radio sky turns out to be a complex mix of star-forming galaxies and radio-quiet AGN evolving at a similar, strong rate and declining radio-loud AGN. While the well-known flattening of the radio number counts below 1 mJy is mostly due to star-forming galaxies, these sources and AGN make up an approximately equal fraction of the sub-mJy sky. Our results shed also light on a fifty-year-old issue, namely radio emission from radio-quiet AGN, and suggest that it is closely related to star formation, at least at z ~ 1.5 - 2. The implications of our findings for future, deeper radio surveys, including those with the Square Kilometre Array, are also discussed. One of the main messages, especially to non-radio astronomers, is that radio surveys are reaching such f...

  17. Bolometric luminosities and Eddington ratios of X-ray selected Active Galactic Nuclei in the XMM-COSMOS survey

    OpenAIRE

    Lusso, E.; Comastri, A.; Simmons, B. D.; M. Mignoli(INAF); Zamorani, G.; Vignali, C.; Brusa, M.; Shankar, F.; Lutz, D.; Trump, J. R.; R. Maiolino; Gilli, R.; Bolzonella, M.; Puccetti, S.; Salvato, M.

    2012-01-01

    Bolometric luminosities and Eddington ratios of both X-ray selected broad-line (Type-1) and narrow-line (Type-2) AGN from the XMM-Newton survey in the COSMOS field are presented. The sample is composed by 929 AGN (382 Type-1 AGN and 547 Type-2 AGN) and it covers a wide range of redshifts, X-ray luminosities and absorbing column densities. About 65% of the sources are spectroscopically identified as either Type-1 or Type-2 AGN (83% and 52% respectively), while accurate photometric redshifts ar...

  18. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). VI: The UV luminosity function of the Virgo cluster and its surrounding regions

    CERN Document Server

    Boselli, A; Voyer, E; Ferrarese, L; Consolandi, G; Cortese, L; Cote, P; Cuillandre, J C; Gavazzi, G; Gwyn, S; Heinis, S; Ilbert, O; MacArthur, L; Roehlly, Y

    2015-01-01

    We use the GALEX data of the GUViCS survey to construct the NUV luminosity function of the Virgo cluster over ~ 300 deg.2, an area covering the cluster and its surrounding regions up to ~ 1.8 virial radii. The NUV luminosity function is also determined for galaxies of different morphological type and NUV-i colour, and for the different substructures within the cluster. These luminosity functions are robust vs. statistical corrections since based on a sample of 833 galaxies mainly identified as cluster members with spectroscopic redshift (808) or high-quality optical scaling relations (10). We fit these luminosity functions with a Schechter function, and compare the fitted parameters with those determined for other nearby clusters and for the field. The faint end slope of the Virgo NUV luminosity function (alpha = -1.19), here sampled down to ~ NUV = -11.5 mag, is significantly flatter than the one measured in other nearby clusters and similar to the field one. Similarly M* = -17.56 is one-to-two magnitudes fa...

  19. Common Envelope Mechanisms: Constraints from the X-ray Luminosity Function of High Mass X-ray Binaries

    CERN Document Server

    Zuo, Zhao-Yu

    2013-01-01

    We use the measured X-ray luminosity function (XLF) of high-mass X-ray binaries (HMXBs) to constrain the common envelope (CE) mechanisms, which usually serve as a key process governing the binary evolution. We show that the XLF can be reproduced quite closely under the canonical energy budget approach for CE evolution, while the angular momentum budget approach seems to predict HMXB population about 1 to 2 orders of magnitude greater than observed. In addition, the value of $\\alpha_{\\rm CE}$ can be constrained to be within about 0.5-1.0. We present the detailed components of the HMXB populations under the angular momentum budget approach and compare them with those in Zuo et al. and observations. We suggest the distinct observational properties, as well as period distributions of HMXBs may provide further clues to discriminate between these two types of CE mechanisms.

  20. A MUSE View of the HUDF: The Lyα Luminosity Function out to z ˜ 6.5

    Science.gov (United States)

    Bryony Drake, Alyssa

    2015-08-01

    I will present first results on the Lyα luminosity function in the Hubble Ultra Deep Field (HUDF), using a large, homogeneous, sample of LAEs selected through blind spectroscopy from MUSE. The unprecedented detection power of MUSE gives us the sensitivity to study the progenitors of L∗ galaxies when the Universe was just ˜ 2 Gyr old. These data therefore probe further down the Lyα LF than ever before, allowing us to reliably constrain the faint end slope, α, at high redshift, as well as assessing the evolution of the Lyα LF between z ˜ 3.0 and z ˜ 6.5. Finally I will show the first assessment from MUSE of the contribution of LAEs to the cosmic SFRD across this redshift range, and discuss the implications of our results on models of galaxy formation and evolution.

  1. A new extensive catalog of optically variable AGN in the GOODS Fields and a new statistical approach to variability selection

    OpenAIRE

    Villforth, Carolin; Koekemoer, Anton M.; Grogin, Norman A.

    2010-01-01

    Variability is a property shared by practically all AGN. This makes variability selection a possible technique for identifying AGN. Given that variability selection makes no prior assumption about spectral properties, it is a powerful technique for detecting both low-luminosity AGN in which the host galaxy emission is dominating and AGN with unusual spectral properties. In this paper, we will discuss and test different statistical methods for the detection of variability in sparsely sampled d...

  2. The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei

    CERN Document Server

    Bentz, Misty C; Grier, Catherine J; Barth, Aaron J; Peterson, Bradley M; Vestergaard, Marianne; Bennert, Vardha N; Canalizo, Gabriela; De Rosa, Gisella; Filippenko, Alexei V; Gates, Elinor L; Greene, Jenny E; Li, Weidong; Malkan, Matthew A; Pogge, Richard W; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak

    2013-01-01

    We present an updated and revised analysis of the relationship between the Hbeta broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of 9 new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hbeta time lag, which is assumed to yield the average Hbeta BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of alpha = 0.533 (+0.035/-0.033), consistent ...

  3. The Angular Clustering of WISE-Selected AGN: Different Haloes for Obscured and Unobscured AGN

    OpenAIRE

    Donoso, E.; Yan, Lin; Stern, D; Assef, R. J.

    2013-01-01

    We calculate the angular correlation function for a sample of 170,000 AGN extracted from the Wide-field Infrared Survey Explorer (WISE) catalog, selected to have red mid-IR colors (W1 - W2 > 0.8) and 4.6 micron flux densities brighter than 0.14 mJy). The sample is expected to be >90% reliable at identifying AGN, and to have a mean redshift of z=1.1. In total, the angular clustering of WISE-AGN is roughly similar to that of optical AGN. We cross-match these objects with the photometric SDSS ca...

  4. Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

    International Nuclear Information System (INIS)

    We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

  5. Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

    Energy Technology Data Exchange (ETDEWEB)

    Pace, Cameron; Salim, Samir, E-mail: cjpace@indiana.edu, E-mail: salims@indiana.edu [Indiana University, Department of Astronomy, Swain Hall West 319, Bloomington, IN 47405-7105 (United States)

    2014-04-10

    We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

  6. Combining Chandra Observations and Near-Infrared Imaging to Search for Dual AGNs Among Double-Peaked [O III] SDSS AGN

    Science.gov (United States)

    McGurk, Rosalie C.; Max, Claire E.; Holden, Bradford; Shields, Gregory A.; Medling, Anne

    2016-01-01

    When galaxies merge, gas accretes onto both central supermassive black holes. Thus, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. We studied a sample of double-peaked SDSS [O III] AGNs using Keck 2 Laser Guide Star Adaptive Optics assisted imaging to find that 30% of double-peaked SDSS AGNs have two spatial components within a 3" radius. However, the identity of the companion object is not revealed with imaging; X-ray observations can confirm these galaxy pairs as systems containing two AGNs. We performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs with a possible near-infrared companion 1-3" away. Using our observations and 8 archival observations of additional candidate dual AGNs, we compare the distribution of X-ray photons to our spatially double near-IR images, measure X-ray luminosities and hardness ratios, and estimate column densities. Additionally, we can compare our near-IR spatially double candidates with 7 double-peaked [O III] SDSS AGNs that are spatially single in our near-IR imaging and have archival Chandra ACIS-S observations. By assessing what fraction of double- peaked emission line SDSS AGNs are true dual AGNs, we can better determine whether double-peaked [O III] is an efficient dual AGN indicator and constrain the statistics of dual AGNs

  7. THE UDF05 FOLLOW-UP OF THE HUBBLE ULTRA DEEP FIELD. III. THE LUMINOSITY FUNCTION AT z ∼ 6

    International Nuclear Information System (INIS)

    In this paper, we present a derivation of the rest-frame 1400 A luminosity function (LF) at redshift six from a new application of the maximum likelihood method by exploring the five deepest Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) fields, i.e., the Hubble Ultra Deep Field, two UDF05 fields, and two Great Observatories Origins Deep Survey fields. We work on the latest improved data products, which makes our results more robust than those of previous studies. We use unbinned data and thereby make optimal use of the information contained in the data set. We focus on the analysis to a magnitude limit where the completeness is larger than 50% to avoid possibly large errors in the faint end slope that are difficult to quantify. We also take into account scattering in and out of the dropout sample due to photometric errors by defining for each object a probability that it belongs to the dropout sample. We find the best-fit Schechter parameters to the z ∼ 6 LF are α = 1.87 ± 0.14, M* = -20.25 ± 0.23, and φ* = 1.77+0.62-0.49 x 10-3 Mpc-3. Such a steep slope suggests that galaxies, especially the faint ones, are possibly the main sources of ionizing photons in the universe at redshift six. We also combine results from all studies at z ∼ 6 to reach an agreement in the 95% confidence level that -20.45 * < -20.05 and -1.90 < α < -1.55. The luminosity density has been found not to evolve significantly between z ∼ 6 and z ∼ 5, but considerable evolution is detected from z ∼ 6 to z ∼ 3.

  8. Population studies in groups and clusters of galaxies. IV. Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    International Nuclear Information System (INIS)

    Published observational data on the Leo, Dorado, NGC 1400, NGC 5044, Antlia, Fornax, and Virgo groups of galaxies are analyzed in terms of the luminosity functions and morphological types of their members. The data sets employed are characterized, and the results are presented in extensive tables and graphs and discussed in detail. While the fractions of early and late galaxies in the groups are similar, the ratio of dwarfs to giants (D/G) in the early galaxies varies monotonically with the richness of the cluster, leading to artificial flattening at the faint end of the total luminosity function in environments with low D/G. The luminosity function for dwarfs in all environments is found to have a slope of about -1.3. 54 refs

  9. Star-formation in the host galaxies of radio-AGN

    CERN Document Server

    Karouzos, Marios; Im, Myungshin; Malkan, Matthew

    2013-01-01

    There exist strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies. It is however still unclear what the exact role of nuclear activity, in the form of accretion onto these supermassive black holes, in this co-evolution is. We use a rich multi-wavelength dataset available for the North Ecliptic Pole field, most notably surveyed by the AKARI satellite infrared telescope to study the host galaxy properties of AGN. In particular we are interested in investigating star-formation in the host galaxies of radio-AGN and the putative radio feedback mechanism, potentially responsible for the eventual quenching of star-formation. Using both broadband SED modeling and optical spectroscopy, we simultaneously study the nu- clear and host galaxy components of our sources, as a function of their radio luminosity, bolo- metric luminosity, and radio-loudness. Here we present preliminary results concerning the AGN content of the radio sources in this field, while offering tentati...

  10. Light, Luminosity and the High Luminosity LHC

    CERN Multimedia

    2015-01-01

    Short interview to Lucio Rossi, project leader of the High Luminosity LHC, about the concept of light in physics, light and luminosity in particle accelerators and the High Luminosity LHC project. On the occasion of International Year of Light 2015.

  11. Luminosity functions in the CLASH-VLT cluster MACS J1206.2-0847: the importance of tidal interactions

    CERN Document Server

    Mercurio, A; Biviano, A; Nonino, M; Rosati, P; Balestra, I; Brescia, M; Girardi, M; Gobat, R; Grillo, C; Lombardi, M; Sartoris, B

    2015-01-01

    We present the optical luminosity functions (LFs) of galaxies for the CLASH-VLT cluster MACS J1206.2-0847 at z=0.439, based on HST and SUBARU data, including ~600 spectroscopically confirmed member galaxies. The LFs on the wide SUBARU FoV are well described by a single Schechter function down to M~M*+3, whereas this fit is poor for HST data, due to a faint-end upturn visible down M~M*+7, suggesting a bimodal behaviour. We also investigate the effect of local environment by deriving the LFs in four different regions, according to the distance from the centre, finding an increase in the faint-end slope going from the core to the outer rings. Our results confirm and extend our previous findings on the analysis of mass functions, which showed that the galaxies with stellar mass below 10^10.5, M_sun have been significantly affected by tidal interaction effects, thus contributing to the intra cluster light.

  12. Misclassified type 1 AGNs in the local universe

    CERN Document Server

    Woo, Jong-Hak; Park, Daeseong; Bae, Hyun-Jin; Kim, Jae-Hyuk; Lee, Seung-Eun; Kim, Sang Chul; Kwon, Hong-Jin

    2014-01-01

    We search for misclassified type 1 AGNs among type 2 AGNs identified with emission line flux ratios, and investigate the properties of the sample. Using 4\\,113 local type 2 AGNs at $0.02AGNs among type 2 AGN sample is $\\sim$3.5%, implying that a large number of missing type 1 AGN population may exist. The misclassified type 1 AGNs have relatively low luminosity with a mean broad \\Ha\\ luminosity, log L$_{H\\alpha} = 40.50\\pm0.35$ \\ergs, while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log M$_{\\rm BH} = 6.94\\pm0.51$ M$_{\\odot}$. The mean Eddington ratio of the sample is log L$_{\\rm bol}$/L$_{\\rm Edd}$ = $-2.00\\pm0.40$, indicating tha...

  13. Bloated Stars as AGN Broad Line Clouds The Emission Line Profiles

    CERN Document Server

    Alexander, T; Alexander, Tal; Netzer, Hagai

    1996-01-01

    The Bloated Stars Scenario proposes that AGN broad line emission originates in the winds or envelopes of bloated stars (BS). Alexander and Netzer (1994) established that ~ 5e4 BSs with dense, decelerating winds can reproduce the observed emission line spectrum and avoid rapid collisional destruction. Here, we use the observed properties of AGN line profiles to further constrain the model parameters. In the BS model, the origin of the broad profiles is the stellar velocity field in the vicinity of the central black hole. We use a detailed photoionization code and a model of the stellar distribution function to calculate the BS emission line profiles and compare them to a large sample of AGN CIV, CIII] and MgII profiles. We find that the BSs can reproduce the general shape and width of typical AGN profiles as well as the line ratios if (i) The ionizing luminosity to black hole mass ratio is low enough. (ii) The broad line region size is limited by some cutoff mechanism. (iii) The fraction of the BSs in the stel...

  14. Dissecting Galaxies: Spatial and Spectral Separation of Emission Excited by Star Formation and AGN Activity

    CERN Document Server

    Davies, Rebecca L; Kewley, Lisa J; Dopita, Michael A; Hampton, Elise J; Shastri, Prajval; Scharwachter, Julia; Sutherland, Ralph; Kharb, Preeti; Bhatt, Harish; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stephanie; Srivastava, Shweta

    2016-01-01

    The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and AGN activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra. In this paper, we describe how integral field data can be used to spectrally and spatially separate emission associated with star formation from emission associated with accretion onto an active galactic nucleus (AGN). We demonstrate our method using integral field data for two AGN host galaxies (NGC 5728 and NGC 7679) from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). The spectra of NGC 5728 and NGC 7679 form clear sequences of AGN fraction on standard emission line ratio diagnostic diagrams. We show that the emission line luminosities of the majority (> 85 per cent) of spectra along each AGN fraction sequence can be reproduced by linear superpositions of the emission line luminosities of one AGN dominated spectrum and one star formation dominated...

  15. The Luminosity Function of Lyman Alpha Emitting Galaxies and Cosmic Reionisation of Hydrogen

    CERN Document Server

    Dijkstra, M; Haiman, Z; Dijkstra, Mark; Wyithe, Stuart; Haiman, Zoltan

    2006-01-01

    Recent observations imply that the observed number counts of Lyman Alpha (Lya) emitters evolved significantly between z=5.7 and z=6.5. It has been suggested that this evolution was due to a rapid evolution in the ionisation state, and hence transmission of the IGM which caused Lya flux from z=6.5 galaxies to be more strongly suppressed. In this paper we show that the observed evolution can be attributed entirely to the evolution in the mass function of dark matter halos housing the Lya emitters. We place constraints on the evolution of transmission in the IGM between z=6.5 and z=5.7, finding a ratio of ~1.2, which may be accounted for by the evolution of the mean IGM density through cosmic expansion. Using a model for IGM transmission, we demonstrate that Lya emitting galaxies at z=6.5 must be embedded in HII bubbles greater than 35x_HI comoving Mpc in size, where x_HI is the neutral fraction of hydrogen outside the ionised bubbles. The model of Furlanetto et al (2006) may be used to translate this into a low...

  16. The XXL Survey. II. The bright cluster sample: catalogue and luminosity function

    CERN Document Server

    Pacaud, F; Giles, P A; Adami, C; Sadibekova, T; Pierre, M; Maughan, B J; Lieu, M; Fèvre, J -P Le; Alis, S; Altieri, B; Ardila, F; Baldry, I; Benoist, C; Birkinshaw, M; Chiappetti, L; Démoclès, J; Eckert, D; Evrard, A E; Faccioli, L; Gastaldello, F; Guennou, L; Horellou, C; Iovino, A; Koulouridis, E; Brun, V Le; Lidman, C; Liske, J; Maurogordato, S; Menanteau, F; Owers, M; Poggianti, B; Pomarède, D; Pompei, E; Ponman, T J; Rapetti, D; Reiprich, T H; Smith, G P; Tuffs, R; Valageas, P; Valtchanov, I; Willis, J P; Ziparo, F

    2015-01-01

    Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of $3\\times 10^{-14}\\,\\mathrm{erg \\,s^{-1}cm^{-2}}$ on the source flux within a 1$^{\\prime}$ aperture. Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On th...

  17. NGC 5548 in a Low-Luminosity State

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Denney, Kelly D.; Cackett, Edward M.;

    2007-01-01

    We describe results from a new ground-based monitoring campaign on NGC 5548, the best studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L(5100) = 4.7 x 10^42 ergs s^-1. We determine a rest-frame time lag between...... reverberation-mapped AGNs as a whole....

  18. Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission

    CERN Document Server

    Takeuchi, Tsutomu T; Yuan, Fang-Ting; Buat, Veronique; Burgarella, Denis

    2012-01-01

    Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of galaxies show a strong evolution from $z = 0$ to $z = 1$, but the FIR LF evolves much stronger than the FUV one. The FUV is dominantly radiated from newly formed short-lived OB stars, while the FIR is emitted by dust grains heated by the FUV radiation field. It is known that dust is always associated with star formation activity. Thus, both FUV and FIR are tightly related to the star formation in galaxies, but in a very complicated manner. In order to disentangle the relation between FUV and FIR emissions, we estimate the UV-IR bivariate LF (BLF) of galaxies with {\\sl GALEX} and {\\sl AKARI} All-Sky Survey datasets. Recently we invented a new mathematical method to construct the BLF with given marginals and prescribed correlation coefficient. This method makes use of a tool from mathematical statistics, so called "copula". The copula enables us to construct a bivariate distribution function from given marginal distributions with prescri...

  19. The space density of Compton-thick AGN at z ≈ 0.8 in the zCOSMOS-Bright Survey

    Science.gov (United States)

    Vignali, C.; Mignoli, M.; Gilli, R.; Comastri, A.; Iwasawa, K.; Zamorani, G.; Mainieri, V.; Bongiorno, A.

    2014-11-01

    Context. The obscured accretion phase in black hole growth is a crucial ingredient in many models linking the active galactic nuclei (AGN) activity with the evolution of their host galaxy. At present, a complete census of obscured AGN is still missing, although several attempts in this direction have been carried out recently, mostly in the hard X-rays and at mid-infrared wavelengths. Aims: The purpose of this work is to assess whether the [Ne v] emission line at 3426 Å can reliably pick up obscured AGN up to z ≈ 1 by assuming that it is a reliable proxy of the intrinsic AGN luminosity and using moderately deep X-ray data to characterize the amount of obscuration. Methods: A sample of 69 narrow-line (Type 2) AGN at z ≈ 0.65-1.20 were selected from the 20k-zCOSMOS Bright galaxy sample on the basis of the presence of the [Ne v]3426 Å emission. The X-ray properties of these galaxies were then derived using the Chandra-COSMOS coverage of the field; the X-ray-to-[Ne v] flux ratio, coupled with X-ray spectral and stacking analyses, was then used to infer whether Compton-thin or Compton-thick absorption is present in these sources. Then the [Ne v] luminosity function was computed to estimate the space density of Compton-thick AGN at z ≈ 0.8. Results: Twenty-three sources were detected by Chandra, and their properties are consistent with moderate obscuration (on average, ≈a few × 1022 cm-2). The X-ray properties of the remaining 46 X-ray undetected Type 2 AGN (among which we expect to find the most heavily obscured objects) were derived using X-ray stacking analysis. Current data, supported by Monte Carlo simulations, indicate that a fraction as high as ≈40% of the present sample is likely to be Compton thick. The space density of Compton-thick AGN with logL2-10 keV> 43.5 at z = 0.83 is ΦThick = (9.1 ± 2.1) × 10-6 Mpc-3, in good agreement with both X-ray background model expectations and the previously measured space density for objects in a similar

  20. Galaxy And Mass Assembly (GAMA): ugrizYJHK S\\'ersic luminosity functions and the cosmic spectral energy distribution by Hubble type

    CERN Document Server

    Kelvin, Lee S; Robotham, Aaron S G; Graham, Alister W; Phillipps, Steven; Agius, Nicola K; Alpaslan, Mehmet; Baldry, Ivan; Bamford, Steven P; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael J I; Colless, Matthew; Conselice, Christopher J; Hopkins, Andrew M; Liske, Jochen; Loveday, Jon; Norberg, Peder; Pimbblet, Kevin A; Popescu, Cristina C; Prescott, Matthew; Taylor, Edward N; Tuffs, Richard J

    2014-01-01

    We report the morphological classification of 3727 galaxies from the Galaxy and Mass Assembly survey with M_r < -17.4 mag and in the redshift range 0.025 < z < 0.06 (2.1 x 10^5 Mpc^3 ) into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr and little blue spheroid classes. Approximately 70% of galaxies in our sample are disk dominated systems, with the remaining ~30% spheroid dominated. We establish the robustness of our classifications, and use them to derive morphological-type luminosity functions and luminosity densities in the ugrizYJHK passbands, improving on prior studies that split by global colour or light profile shape alone. We find that the total galaxy luminosity function is best described by a double-Schechter function while the constituent morphological-type luminosity functions are well described by a single-Schechter function. These data are also used to derive the star-formation rate densities for each Hubble class, and the attenuated and unattenuated (corrected for dust) cosmic spectral...

  1. The Next Generation Virgo Cluster Survey (NGVS). XIII. The Luminosity and Mass Function of Galaxies in the Core of the Virgo Cluster and the Contribution from Disrupted Satellites

    CERN Document Server

    Ferrarese, Laura; Sanchez-Janssen, Ruben; Roediger, Joel; McConnachie, Alan W; Durrell, Patrick R; MacArthur, Lauren A; Blakeslee, John P; Duc, Pierre-Alain; Boissier, S; Boselli, Alessandro; Courteau, Stephane; Cuillandre, Jean-Charles; Emsellem, Eric; Gwyn, S D J; Guhathakurta, Puragra; Jordan, Andres; Lancon, Ariane; Liu, Chengze; Mei, Simona; Mihos, J Christopher; Puzia, Thomas H; Taylor, James E; Zhang, Hongxin

    2016-01-01

    We present measurements of the galaxy luminosity and stellar mass function in a 3.71 deg$^2$ (0.3 Mpc$^2$) area in the core of the Virgo cluster, based on $ugriz$ data from the Next Generation Virgo Cluster Survey (NGVS). The galaxy sample consists of 352 objects brighter than $M_g=-9.13$ mag, the 50% completeness limit of the survey. Using a Bayesian analysis, we find a best-fit faint end slope of $\\alpha=-1.33 \\pm 0.02$ for the g-band luminosity function; consistent results are found for the stellar mass function as well as the luminosity function in the other four NGVS bandpasses. We discuss the implications for the faint-end slope of adding 92 ultra compact dwarfs galaxies (UCDs) -- previously compiled by the NGVS in this region -- to the galaxy sample, assuming that UCDs are the stripped remnants of nucleated dwarf galaxies. Under this assumption, the slope of the luminosity function (down to the UCD faint magnitude limit, $M_g = -9.6$ mag) increases dramatically, up to $\\alpha = -1.60 \\pm 0.06$ when cor...

  2. PRIMUS: An observationally motivated model to connect the evolution of the AGN and galaxy populations out to z~1

    CERN Document Server

    Aird, James; Moustakas, John; Diamond-Stanic, Aleksandar M; Blanton, Michael R; Cool, Richard J; Eisenstein, Daniel J; Wong, Kenneth C; Zhu, Guangtun

    2013-01-01

    We present an observationally motivated model to connect the AGN and galaxy populations at 0.2AGN X-ray luminosity function (XLF). We start with measurements of the stellar mass function of galaxies (from the Prism Multi-object Survey) and populate galaxies with AGNs using models for the probability of a galaxy hosting an AGN as a function of specific accretion rate (the rate of supermassive black hole growth scaled relative to the host stellar mass). Our model is based on measurements indicating that the specific accretion rate distribution is a universal function across a wide range of host stellar mass with slope gamma_1=0.65 and an overall normalization that evolves strongly with redshift. We test several simple assumptions to extend this model to high specific accretion rates (beyond the measurements) and compare the predictions for the XLF with the observed data. We find good agreement with a model that allows for a break in the specific accretion rate distribution at a poin...

  3. Ultra-faint ultraviolet galaxies at z ∼ 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    International Nuclear Information System (INIS)

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ∼ 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ≥ 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100× fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range –19.5 < M 1500 < –13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be α = –1.74 ± 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M 1500 = –13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B – V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z ☉) compared to their brighter counterparts (Z ☉), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ∼ 2 is 4.31−0.60+0.68×1026 erg s–1 Hz–1 Mpc–3, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ∼ 2 (assuming a constant dust extinction correction of 4.2 over all luminosities and a Kroupa

  4. AGNs and galaxy interactions

    OpenAIRE

    Alonso, M. Sol; Lambas, Diego G.; Tissera, Patricia; Coldwell, Georgina

    2007-01-01

    We perform a statistical analysis of AGN host characteristics and nuclear activity for AGNs in pairs and without companions. Our study concerns a sample of AGNs derived from the SDSS-DR4 data by Kauffmann et al (2003) and pair galaxies obtained from the same data set by Alonso et al. (2006). An eye-ball classification of images of 1607 close pairs ($r_p

  5. The Spitzer mid-infrared AGN survey. I - optical and near-infrared spectroscopy of candidate obscured and normal AGN selected in the mid-infrared

    CERN Document Server

    Lacy, M; Gates, E L; Nielsen, D M; Petric, A O; Sajina, A; Urrutia, T; Drews, S Cox; Harrison, C; Seymour, N; Storrie-Lombardi, L J

    2013-01-01

    We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate Active Galactic Nuclei (AGN) selected in the mid-infrared. This survey selects both normal and obscured AGN closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L_bol~10^10L_sun, to highly luminous quasars (L_bol~10^14L_sun), and with redshifts from 0-4.3. Samples of candidate AGN were selected through mid-infrared color cuts at several different 24 micron flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGN and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type-1 AGN with blue continua, 294 (44%) are type-2 objects with extinctions A_V>~5 towards their AGN, 96 (14%) are AGN with lower extinctions (A_V~1) and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. 50% of the survey objects have L_bol >10^12L_sun, in the quasar ...

  6. Galaxies in filaments have more satellites: the influence of the cosmic web on the satellite luminosity function in the SDSS

    CERN Document Server

    Guo, Quan; Libeskind, Noam I

    2014-01-01

    We investigate if the satellite luminosity function (LFs) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS DR8) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample while potential satellites are searched for in the much deeper photometric sample. Filaments are constructed from the galaxy distribution by the "Bisous" process. Isolated primary galaxies are divided into two subsamples: those in filaments and those not in filaments. We examine the stacked mean LF of each sample and found that, in the mean, the satellite LFs of primary galaxies (extending to at least 4 magnitude fainter than the primary galaxies) in filaments is significantly higher than those of primary galaxies not in filaments. The filamentary environment can increases the abundance of the brightest satellites ($M_\\mathrm{sat.} < M_\\mathrm{prim.}+ 2.0$), by a factor of $\\sim 2$ compared with non-filament galaxies. This result is independent ...

  7. Supernova Remnants in the Local Group I: A model for the radio luminosity function and visibility times of supernova remnants

    CERN Document Server

    Sarbadhicary, Sumit K; Chomiuk, Laura; Caprioli, Damiano; Huizenga, Daniel

    2016-01-01

    Supernova remnants (SNRs) in Local Group galaxies offer unique insights into the origin of different types of supernovae. In order to take full advantage of these insights, one must understand the intrinsic and environmental diversity of SNRs in the context of their host galaxies. We introduce a semi-analytic model that reproduces the statistical properties of a radio continuum-selected SNR population, taking into account the detection limits of radio surveys, the range of SN kinetic energies, the measured ISM and stellar mass distribution in the host galaxy from multi-wavelength images and the current understanding of electron acceleration and field amplification in SNR shocks from first-principle kinetic simulations. Applying our model to the SNR population in M33, we reproduce the SNR radio luminosity function with a median SN rate of $\\sim 3.1 \\times 10^{-3}$ per year and an electron acceleration efficiency, $\\epsilon_{\\rm{e}} \\sim 4.2 \\times 10^{-3}$. We predict that the radio visibility times of $\\sim 7...

  8. The bright end of the galaxy luminosity function at z ~ 7: before the onset of mass quenching?

    CERN Document Server

    Bowler, R A A; McLure, R J; Rogers, A B; McCracken, H J; Milvang-Jensen, B; Furusawa, H; Fynbo, J P U; Taniguchi, Y; Afonso, J; Bremer, M N; Fevre, O Le

    2013-01-01

    We present the results of a new search for bright star-forming galaxies at z ~ 7 within the UltraVISTA DR2 and UKIDSS UDS DR10 data, which together provide 1.65 sq deg of near-infrared imaging with overlapping optical and Spitzer data. Using a full photo-z analysis to identify high-z galaxies and reject contaminants, we have selected a sample of 34 luminous (-22.7 < M_UV < -21.2) galaxies with the 6.5 < z < 7.5. Crucially, the deeper imaging provided by UltraVISTA DR2 confirms all of the robust objects previously uncovered by Bowler et al. (2012), validating our selection technique. Our sample includes the most massive galaxies known at z ~ 7, with M_* ~ 10^{10} M_sun, and the majority are resolved, consistent with larger sizes (r_{1/2} ~ 1 - 1.5 kpc) than displayed by less massive galaxies. From our final sample, we determine the form of the bright end of the rest-frame UV galaxy luminosity function (LF) at z ~ 7, providing strong evidence that the bright end of the z = 7 LF does not decline as s...

  9. RECONSTRUCTING THE NEAR-INFRARED BACKGROUND FLUCTUATIONS FROM KNOWN GALAXY POPULATIONS USING MULTIBAND MEASUREMENTS OF LUMINOSITY FUNCTIONS

    International Nuclear Information System (INIS)

    We model fluctuations in the cosmic infrared background (CIB) arising from known galaxy populations using 233 measured UV, optical, and near-IR luminosity functions (LFs) from a variety of surveys spanning a wide range of redshifts. We compare best-fit Schechter parameters across the literature and find clear indication of evolution with redshift. Providing fitting formulae for the multi-band evolution of the LFs out to z ∼ 5, we calculate the total emission redshifted into the near-IR bands in the observer frame and recover the observed optical and near-IR galaxy counts to good accuracy. Our empirical approach, in conjunction with a halo model describing the clustering of galaxies, allows us to compute the fluctuations of the unresolved CIB and compare the models to current measurements. We find that fluctuations from known galaxy populations are unable to account for the large-scale CIB clustering signal seen by Spitzer/IRAC and AKARI/IRC and continue to diverge out to larger angular scales. This holds true even if the LFs are extrapolated out to faint magnitudes with a steep faint-end slope all the way to z = 8. We also show that removing resolved sources to progressively fainter magnitude limits isolates CIB fluctuations to increasingly higher redshifts. Our empirical approach suggests that known galaxy populations are not responsible for the bulk of the fluctuation signal seen in the measurements and favors a very faint population of highly clustered sources.

  10. The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability

    CERN Document Server

    Kennedy, Grant M

    2013-01-01

    We present the first characterisation of the 12um warm dust ("exo-Zodi") luminosity function around Sun-like stars, focussing on the dustiest systems that can be identified by WISE. We detect six new warm dust candidates, five of which have unknown ages. We show that the dustiest old (>Gyr) systems BD+20 307 and HD 15407A are 1 in 10,000 occurrences. Bright warm dust is more common around young (<120Myr) systems, with a ~1% occurrence rate. We show that a two component in situ model where all stars have initially massive warm disks and in which warm debris is also generated at some random time along the stars' main-sequence lifetime, perhaps due to a collision, can explain the observations. However, if all stars only have initially massive warm disks these would not be visible at Gyr ages, and random collisions on the main-sequence are too infrequent to explain the high disk occurrence rate for young stars. That is, neither component can explain the observations on their own. Despite these conclusions, we ...

  11. The UDF05 Follow-up of the Hubble Ultra Deep Field. III. The Luminosity Function at z~6

    CERN Document Server

    Su, Jian; Oesch, Pascal; Trenti, Michele; Bergeron, Eddie; Bradley, Larry; Carollo, Marcella; Dahlen, Tomas; Ferguson, Henry C; Giavalisco, Mauro; Koekemoer, Anton; Lilly, Simon; Lucas, Ray A; Mobasher, Bahram; Panagia, Nino; Pavlovsky, Cheryl

    2011-01-01

    In this paper, we present a derivation of the rest-frame 1400A luminosity function (LF) at redshift six from a new application of the maximum likelihood method by exploring the five deepest HST/ACS fields, i.e., the HUDF, two UDF05 fields, and two GOODS fields. We work on the latest improved data products, which makes our results more robust than those of previous studies. We use un-binned data and thereby make optimal use of the information contained in the dataset. We focus on the analysis to a magnitude limit where the completeness is larger than 50% to avoid possibly large errors in the faint end slope that are difficult to quantify. We also take into account scattering in and out of the dropout sample due to photometric errors by defining for each object a probability that it belongs to the dropout sample. We find the best fit Schechter parameters to the z~6 LF are: alpha = 1.87 +/- 0.14, M* = -20.25 +/- 0.23, and phi*=1.77^{+0.62}_{-0.49} * 10^{-3} Mpc^{-3}. Such a steep slope suggests that galaxies, es...

  12. Recent Arrival of Faint Cluster Galaxies on the Red-sequence: Luminosity Functions from 119 square degrees of CFHTLS

    CERN Document Server

    Lu, Ting; Balogh, Michael L; Bognat, Adam

    2009-01-01

    The global star formation rate has decreased significantly since z ~ 1, for reasons that are not well understood. Red-sequence galaxies, dominating in galaxy clusters, represent the population that have had their star formation shut off, and may therefore be the key to this problem. In this work, we select 127 rich galaxy clusters at 0.17luminosity functions (LFs). We show that the faint end of the LF is very sensitive to how red-sequence galaxies are selected, and an optimal way to minimise the contamination from the blue cloud is to mirror galaxies on the redder side of the colour-magnitude relation (CMR). The LFs of our sample have a significant inflexion centred at Mr' ~- 18.5, suggesting a mixture of two populations. Combining our survey with low redshift samples constructed from the Sloan Digital Sky Survey, we show that there is no strong evolu...

  13. The evolution of the galaxy luminosity function in the rest frame blue band up to z=3.5

    CERN Document Server

    Poli, F; Fontana, A; Menci, N; Zamorani, G; Nonino, M; Saracco, P; Vanzella, E; Donnarumma, I; Salimbeni, S; Cimatti, A; Cristiani, S; Daddi, E; D'Odorico, S; Mignoli, M; Pozzetti, L; Renzini, A

    2003-01-01

    We present an estimate of the cosmological evolution of the field galaxy luminosity function (LF) in the rest frame 4400 Angstrom B -band up to redshift z=3.5. To this purpose, we use a composite sample of 1541 I--selected galaxies selected down to I_(AB)=27.2 and 138 galaxies selected down to K_(AB)=25 from ground-based and HST multicolor surveys, most notably the new deep JHK images in the Hubble Deep Field South (HDF-S) taken with the ISAAC instrument at the ESO-VLT telescope. About 21% of the sample has spectroscopic redshifts, and the remaining fraction well calibrated photometric redshifts. The resulting blue LF shows little density evolution at the faint end with respect to the local values, while at the bright end (M_B(AB)<-20) a brightening increasing with redshift is apparent with respect to the local LF. Hierarchical CDM models overpredict the number of faint galaxies by about a factor 3 at z=1. At the bright end the predicted LFs are in reasonable agreement only at low and intermediate redshift...

  14. CONSTRAINTS ON THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z ∼ 5 IN THE COSMOS FIELD

    International Nuclear Information System (INIS)

    We present the result of our low-luminosity quasar survey in the redshift range of 4.5 ∼–7 Mpc–3 mag–1 for –24.52 1450 –7 Mpc–3 mag–1 for –23.52 1450 1450 ∼ –23), being similar to the trend found for quasars with high luminosity (M1450 < –26). This result is consistent with the so-called downsizing evolution of quasars seen at lower redshifts.

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  16. The role of cluster mergers and travelling shocks in shaping the H$\\alpha$ luminosity function at $\\bf z\\sim0.2$: `sausage' and `toothbrush' clusters

    CERN Document Server

    Stroe, Andra; Röttgering, Huub J A; van Weeren, Reinout J

    2013-01-01

    The most extreme cluster mergers can lead to massive cluster-wide travelling shock waves. The CIZA J2242.8+5301 ('sausage') and 1RXS J0603.3+4213 (`toothbrush') clusters ($z\\sim0.2$) host enormous radio-emitting shocks with simple geometry. We investigate the role of mergers and shocks in shaping the H$\\alpha$ luminosity function, using custom-made narrow-band filters matching the cluster redshifts mounted on the INT. We surveyed $\\sim0.28$ deg$^2$ for each cluster and found $181$ line emitters in the `sausage' (volume of $3.371\\times10^3$ Mpc$^3$ for H$\\alpha$ at $z=0.1945$) and $141$ in the `toothbrush' ($4.546\\times10^3$ Mpc$^3$ for H$\\alpha$ at $z=0.225$), out of which $49$ (`sausage') and $30$ (`toothbrush') are expected to be H$\\alpha$. We build luminosity functions for the field-of-view down to an average limiting star formation rate of $0.14$ M$_{\\odot}$ yr$^{-1}$, find good agreement with field luminosity functions at $z=0.2$, but significant differences between the shapes of the luminosity functions...

  17. Ultra-faint Ultraviolet Galaxies at z~2 Behind the Lensing Cluster Abell 1689: the Luminosity Function, Dust Extinction and Star Formation Rate Density

    CERN Document Server

    Alavi, Anahita; Richard, Johan; Stark, Daniel P; Scarlata, Claudia; Teplitz, Harry I; Freeman, William R; Dominguez, Alberto; Rafelski, Marc; Robertson, Brant; Kewley, Lisa

    2013-01-01

    We have obtained deep HST ultraviolet (F275W/F336W) imaging of the lensing cluster Abell1689. The images are used to identify z~2 star-forming galaxies via their Lyman break. Because of the unprecedented depth of the images and the large magnification provided by the cluster, we detect galaxies 100x fainter than previous surveys at this redshift. After removing multiple images, we have 58 galaxies in our sample between -19.5 3. There is no turnover in the luminosity function down to MUV = -13. The observed trend of increasingly redder UV spectral slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of = 0.15. We assume the stars in these galaxies are metal poor (0.2 Z_{sun}) compared to their brighter counterparts (Z_{sun}), resulting in bluer assumed intrinsic UV slopes and larger derived dust extinction. The total UV luminosity density at z~2 is 4.3 x 10^26 erg/s/Hz/Mpc^3, 80% of which is emitted by galaxies in the luminosity...

  18. Radius-luminosity and mass-luminosity relationships for active galactic nuclei

    International Nuclear Information System (INIS)

    Broad-line region (BLR) sizes derived from spectral variability and BLR line widths are used to directly derive the mass (M) of the central objects of ten active galactic nuclei (AGNs) in a uniform manner. It is shown that the luminosity-weighted C IV 1549-emitting BLR radius (R) correlates with the bolometric luminosity L(Bol) and is consistent with R about sq rt L(Bol). The measurements also permit a verification of the Dibai mass-luminosity (M-L) relationship (previously derived indirectly). It is found that L(Bol) is proportional to M exp (1.1 + or - 0.3). It is found that the efficiency factor epsilon, defined as the ratio of L(Bol) to the Eddington luminosity increases from 0.03 in the low-luminosity Seyferts up to 0.06 in the most luminous objects in the sample. 19 refs

  19. The effect of AGN feedback on the X-ray morphologies of clusters: Simulations vs. observations

    Science.gov (United States)

    Chon, Gayoung; Puchwein, Ewald; Böhringer, Hans

    2016-07-01

    Clusters of galaxies probe the large-scale distribution of matter and are a useful tool to test the cosmological models by constraining cosmic structure growth and the expansion of the Universe. It is the scaling relations between mass observables and the true mass of a cluster through which we obtain the cosmological constraints by comparing to theoretical cluster mass functions. These scaling relations are, however, heavily influenced by cluster morphology. The presence of the slight tension in recent cosmological constraints on Ωm and σ8 based on the CMB and clusters has boosted the interests in looking for possible sources for the discrepancy. Therefore we study here the effect of active galactic nucleus (AGN) feedback as one of the major mechanisms modifying the cluster morphology influencing scaling relations. It is known that AGN feedback injects energies up to 1062 erg into the intracluster medium, controls the heating and cooling of a cluster, and re-distributes cold gas from the centre to outer radii. We have also learned that cluster simulations with AGN feedback can reproduce observed cluster properties, for example, the X-ray luminosity, temperature, and cooling rate at the centre better than without the AGN feedback. In this paper using cosmological hydrodynamical simulations we investigate how the AGN feedback changes the X-ray morphology of the simulated systems, and compare this to the observed Representative XMM-Newton Cluster Structure Survey (REXCESS) clusters. We apply two substructure measures, centre shifts (w) and power ratios (e.g. P3/P0), to characterise the cluster morphology, and find that our simulated clusters are more substructured than the observed clusters based on the values of w and P3/P0. We also show that the degree of this discrepancy is affected by the inclusion of AGN feedback. While the clusters simulated with the AGN feedback are in much better agreement with the REXCESS LX-T relation, they are also more substructured

  20. X-ray absorption, nuclear infrared emission and dust covering factors of AGN: testing Unification Schemes

    CERN Document Server

    Mateos, S; Alonso-Herrero, A; Hernán-Caballero, A; Barcons, X; Ramos, A Asensio; Watson, M G; Blain, A; Caccianiga, A; Ballo, L; Braito, V; Almeida, C Ramos

    2016-01-01

    We present the distributions of geometrical covering factors of active galactic nuclei (AGNs) dusty tori (f2) using an X-ray selected complete sample of 227 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The AGN have z from 0.05 to 1.7, 2-10 keV luminosities between 10^42 and 10^46 erg/s and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS and the Wide-field Infrared Survey Explorer in a previous work we determined the rest-frame 1-20 microns continuum emission from the torus which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGN are intrinsically different, with type 2 AGN having on average tori with higher f2 than type 1 AGN. Nevertheless, ~20 per cent of type 1 AGN have tori with large covering factors while ~23-28 per cent of type 2 AGN have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGN the effect is certainly small. f2 in...

  1. The massive end of the luminosity and stellar mass functions and clustering from CMASS to SDSS: Evidence for and against passive evolution

    CERN Document Server

    Bernardi, M; Sheth, R K; Huertas-Company, M; Maraston, C; Shankar, F; Vikram, V

    2015-01-01

    We describe the luminosity function, based on Sersic fits to the light profiles, of CMASS galaxies at z ~ 0.55. Compared to previous estimates, our Sersic-based reductions imply more luminous, massive galaxies, consistent with the effects of Sersic- rather than Petrosian or de Vaucouleur-based photometry on the Sloan Digital Sky Survey (SDSS) main galaxy sample at z ~ 0.1. This implies a significant revision of the high mass end of the correlation between stellar and halo mass. Inferences about the evolution of the luminosity and stellar mass functions depend strongly on the assumed, and uncertain, k+e corrections. In turn, these depend on the assumed age of the population. Applying k+e corrections taken from fitting the models of Maraston et al. (2009) to the colors of both SDSS and CMASS galaxies, the evolution of the luminosity and stellar mass functions appears impressively passive, provided that the fits are required to return old ages. However, when matched in comoving number- or luminosity-density, the...

  2. The 2dF-SDSS LRG and QSO Survey: the QSO luminosity function at 0.4

    CERN Document Server

    Croom, Scott M; Shanks, Tom; Boyle, Brian J; Strauss, Michael A; Myers, Adam D; Nichol, Robert C; Pimbblet, Kevin A; Ross, Nicholas P; Schneider, Donald P; Sharp, Robert G; Wake, David A

    2009-01-01

    We present the QSO luminosity function of the completed 2dF-SDSS LRG and QSO (2SLAQ) survey, based on QSOs photometrically selected from Sloan Digital Sky Survey imaging data and then observed spectroscopically using the 2dF instrument on the Anglo-Australian Telescope. We analyse 10637 QSOs in the redshift range 0.420.0, as found previously by Richards et al. (2005). The luminosity function is consistent with other previous, much smaller, samples produced to the depth of 2SLAQ. By combining the 2SLAQ and SDSS QSO samples we produce a QSO luminosity function with an unprecedented combination of precision and dynamic range. With this we are able to accurately constrain both the bright and faint ends of the QSO LF. While the overall trends seen in the evolution of the QSO LF appear similar to pure luminosity evolution, the data show very significant departures from such a model. Most notably we see clear evidence that the number density of faint QSOs peaks at lower redshift than bright QSOs : QSOs with Mg>-23 h...

  3. MUSE Deep-Fields: The Lya Luminosity Function in the Hubble Deep Field South at 2.91 < z < 6.64

    CERN Document Server

    Drake, Alyssa B; Blaizot, Jeremy; Wisotzki, Lutz; Herenz, Edmund Christian; Garel, Thibault; Richard, Johan; Bacon, Roland; Bina, David; Cantalupo, Sebastiano; Contini, Thierry; Brock, Mark den; Hashimoto, Takuya; Marino, Raffaella Anna; Pello, Roser; Schaye, Joop; Schmidt, Kasper B

    2016-01-01

    We present the first estimate of the Ly{\\alpha} luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field South. Using automatic source-detection software, we assemble a homogeneously-detected sample of 59 Ly{\\alpha} emitters covering a flux range of -18.0 < log10 (F) < -16.3 (erg s^-1 cm^-2), corresponding to luminosities of 41.4 < log10 (L) < 42.8 (erg s^-1). As recent studies have shown, Ly{\\alpha} fluxes can be underestimated by a factor of two or more via traditional methods, and so we undertake a careful assessment of each object's Ly{\\alpha} flux using a curve-of-growth analysis to account for extended emission. We describe our self-consistent method for determining the completeness of the sample, and present an estimate of the global Ly{\\alpha} luminosity function between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find the luminosity function is higher than many number densities reported in the literature by ...

  4. Radio Loud AGNs are Mergers

    CERN Document Server

    Chiaberge, Marco; Lotz, Jennifer; Norman, Colin

    2015-01-01

    We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei at z>1 using new samples. The objects have HST images taken with WFC3 in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z>1 and to a sample of non-active galaxies. We also consider lower redshift radio galaxies with HST observations and previous generation instruments (NICMOS and WFPC2). The full sample spans an unprecedented range in both redshift and AGN luminosity. We perform statistical tests to determine whether the different samples are differently associated with mergers. We find that all (92%) radio-loud galaxies at z>1 are associated with recent or ongoing merger events. Among the radio-loud population there is no evidence for any dependence of the merger fraction on either redshift or AGN power. For the matched radio-quiet samples, only 38% are merging systems. The merger fraction for the sample of non-active galaxies at z>1 is indistinguishable from radio-quiet objects. This...

  5. Optical spectral index - luminosity relation for the 17 mapped Palomar-Green quasars

    OpenAIRE

    Zhang, Xueguang

    2013-01-01

    In this paper, the optical spectra index - luminosity relationship is checked for the well-known 17 individual mapped QSOs, in order to give one more clearer conclusion on the so far conflicting dependence of the spectral index on the luminosity for AGN. Different from the global relationships based on the color difference (photometry parameters) for samples of AGN, the more reliable relationship is determined for the multi-epoch observed individual mapped QSOs with no contamination from the ...

  6. THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z ∼ 4: IMPLICATIONS FOR IONIZATION OF THE INTERGALACTIC MEDIUM AND COSMIC DOWNSIZING

    International Nuclear Information System (INIS)

    We present an updated determination of the z ∼ 4 QSO luminosity function (QLF), improving the quality of the determination of the faint end of the QLF presented by Glikman et al. (2010). We have observed an additional 43 candidates from our survey sample, yielding one additional QSO at z = 4.23 and increasing the completeness of our spectroscopic follow-up to 48% for candidates brighter than R = 24 over our survey area of 3.76 deg2. We study the effect of using K-corrections to compute the rest-frame absolute magnitude at 1450 A compared with measuring M1450 directly from the object spectra. We find a luminosity-dependent bias: template-based K-corrections overestimate the luminosity of low-luminosity QSOs, likely due to their reliance on templates derived from higher luminosity QSOs. Combining our sample with bright quasars from the Sloan Digital Sky Survey and using spectrum-based M1450 for all the quasars, we fit a double power law to the binned QLF. Our best fit has a bright-end slope, α = 3.3 ± 0.2, and faint-end slope, β = 1.6+0.8-0.6. Our new data revise the faint-end slope of the QLF down to flatter values similar to those measured at z ∼ 3. The break luminosity, though poorly constrained, is at M* = -24.1+0.7-1.9, approximately 1-1.5 mag fainter than at z ∼ 3. This QLF implies that QSOs account for about half the radiation needed to ionize the intergalactic medium at these redshifts.

  7. X-Ray Absorption, Nuclear Infrared Emission, and Dust Covering Factors of AGNs: Testing Unification Schemes

    Science.gov (United States)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X.; Asensio Ramos, A.; Watson, M. G.; Blain, A.; Caccianiga, A.; Ballo, L.; Braito, V.; Ramos Almeida, C.

    2016-03-01

    We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2-10 keV luminosities between 1042 and 1046 erg s-1, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1-20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f2 than type 1 AGNs. Nevertheless, ˜20% of type 1 AGNs have tori with large covering factors, while ˜23%-28% of type 2 AGNs have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f2 increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f2 determine the optical appearance of an AGN and control the shape of the rest-frame ˜1-20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.

  8. Satellites of Radio AGN in SDSS: Insights into AGN Triggering and Feedback

    CERN Document Server

    Pace, Cameron

    2014-01-01

    We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7,220 radio AGNs at z < 0.3 (identified by Best & Heckman 2012 from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17{\\sigma} significance) in the number of satellites within 100 kpc even though the cluster membership was controlled for (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via t...

  9. Spectral Decomposition of Broad-Line AGNs and Host Galaxies

    CERN Document Server

    Vanden Berk, Daniel E; Yip, C W; Schneider, D P; Connolly, A J; Burton, R E; Jester, S; Hall, P B; Szalay, A S; Brinkmann, J; Berk, Daniel E. Vanden; Shen, Jiajian; Yip, Ching-Wa; Schneider, Donald P.; Connolly, Andrew J.; Burton, Ross E.; Jester, Sebastian; Hall, Patrick B.; Szalay, Alex S.; Brinkmann, John

    2005-01-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasing...

  10. The Exosat spectral survey of AGN

    Science.gov (United States)

    Turner, T. J.; Pounds, K. A.

    1989-01-01

    Results are presented from Exosat observations of 48 hard X-ray selected Seyfert-type active galactic nuclei (AGN). These include all 30 of the emission line AGN in the Piccinotti (1981) sample. Combining Exosat LE and ME data has yielded X-ray spectra over the broad energy range 0.1-10 keV. Spectra in the about 2-10 keV range are found to be well described by a simple power law, with a narrow distribution of spectral indices across the sample about a mean energy index alpha = 0.70. Exosat has also revealed a substantial number of sources with complex soft X-ray spectra. Evidence that soft emission components occur in many Seyferts, together with detection of rapid variability in the soft component, provides a quantitative support for an accretion disk model for AGN. Approximately half of the present sample of AGN show low-energy absorption attributable to substantial cold matter within the host galaxy. A few cases show evidence for column variability and reduced low-energy opacity (by photo-ionization). These results and the observed rarity of intrinsic absorption in the higher luminosity sources suggest the absorbing matter lies close to the central continuum source.

  11. AGN variability at hard X-rays

    CERN Document Server

    Soldi, S; Beckmann, V; Lubinski, P

    2010-01-01

    We present preliminary results on the variability properties of AGN above 20 keV in order to show the potential of the INTEGRAL IBIS/ISGRI and Swift/BAT instruments for hard X-ray timing analysis of AGN. The 15-50 keV light curves of 36 AGN observed by BAT during 5 years show significantly larger variations when the blazar population is considered (average normalized excess variance = 0.25) with respect to the Seyfert one (average normalized excess variance = 0.09). The hard X-ray luminosity is found to be anti-correlated to the variability amplitude in Seyfert galaxies and correlated to the black hole mass, confirming previous findings obtained with different AGN hard X-ray samples. We also present results on the Seyfert 1 galaxy IC 4329A, as an example of spectral variability study with INTEGRAL/ISGRI data. The position of the high-energy cut-off of this source is found to have varied during the INTEGRAL observations, pointing to a change of temperature of the Comptonising medium. For several bright Seyfert...

  12. ALMA spectroscopic survey in the Hubble Ultra Deep Field: CO luminosity functions and the evolution of the cosmic density of molecular gas

    CERN Document Server

    Decarli, Roberto; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R J; Popping, Gergö; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto; Bauer, Franz; Bell, Eric F; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Fevre, Olivier Le; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

    2016-01-01

    In this paper we use ASPECS, the ALMA Spectroscopic Survey in the {\\em Hubble} Ultra Deep Field (UDF) in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of redshift up to $z\\sim 4.5$. This study is based on galaxies that have been solely selected through their CO emission and not through any other property. In all of the redshift bins the ASPECS measurements reach the predicted `knee' of the CO luminosity function (around $5\\times10^{9}$ K km/s pc$^2$). We find clear evidence of an evolution in the CO luminosity function with respect to $z\\sim 0$, with more CO luminous galaxies present at $z\\sim 2$. The observed galaxies at $z\\sim 2$ also appear more gas-rich than predicted by recent semi-analytical models. The comoving cosmic molecular gas density within galaxies as a function of redshift shows a factor 3-10 drop from $z \\sim 2$ to $z \\sim 0$ (with significant error bars), and possibly a decline at $z>3$. This tre...

  13. A molecular line scan in the Hubble deep field north: Constraints on the co luminosity function and the cosmic H{sub 2} density

    Energy Technology Data Exchange (ETDEWEB)

    Walter, F.; Decarli, R.; Da Cunha, E. [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Sargent, M. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette cedex (France); Carilli, C. [NRAO, Pete V. Domenici Array Science Center, P.O. Box O, Socorro, NM 87801 (United States); Dickinson, M.; Daddi, E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Riechers, D. [Cornell University, 220 Space Sciences Building, Ithaca, NY 14853 (United States); Ellis, R. [Astronomy Department, California Institute of Technology, MC105-24, Pasadena, CA 91125 (United States); Stark, D.; Weiner, B. [Steward Observatory, University of Arizona, 933 North Cherry Street, Tucson, AZ 85721 (United States); Aravena, M. [European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Bell, E. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Bertoldi, F. [Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany); Cox, P.; Downes, D.; Neri, R. [IRAM, 300 rue de la piscine, F-38406 Saint-Martin d' Hères (France); Lentati, L.; Maiolino, R. [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Menten, K. M., E-mail: walter@mpia.de [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); and others

    2014-02-20

    We present direct constraints on the CO luminosity function at high redshift and the resulting cosmic evolution of the molecular gas density, ρ{sub H{sub 2}}(z), based on a blind molecular line scan in the Hubble Deep Field North (HDF-N) using the IRAM Plateau de Bure Interferometer. Our line scan of the entire 3 mm window (79-115 GHz) covers a cosmic volume of ∼7000 Mpc{sup 3}, and redshift ranges z < 0.45, 1.01 < z < 1.89 and z > 2. We use the rich multiwavelength and spectroscopic database of the HDF-N to derive some of the best constraints on CO luminosities in high redshift galaxies to date. We combine the blind CO detections in our molecular line scan (presented in a companion paper) with stacked CO limits from galaxies with available spectroscopic redshifts (slit or mask spectroscopy from Keck and grism spectroscopy from the Hubble Space Telescope) to give first blind constraints on high-z CO luminosity functions and the cosmic evolution of the H{sub 2} mass density ρ{sub H{sub 2}}(z) out to redshifts z ∼ 3. A comparison to empirical predictions of ρ{sub H{sub 2}}(z) shows that the securely detected sources in our molecular line scan already provide significant contributions to the predicted ρ{sub H{sub 2}}(z) in the redshift bins (z) ∼ 1.5 and (z) ∼ 2.7. Accounting for galaxies with CO luminosities that are not probed by our observations results in cosmic molecular gas densities ρ{sub H{sub 2}}(z) that are higher than current predictions. We note, however, that the current uncertainties (in particular the luminosity limits, number of detections, as well as cosmic volume probed) are significant, a situation that is about to change with the emerging ALMA observatory.

  14. Understanding the observed evolution of the galaxy luminosity function from z = 6–10 in the context of hierarchical structure formation

    International Nuclear Information System (INIS)

    Recent observations of the Lyman-break galaxy (LBG) luminosity function (LF) from z ≈ 6–10 show a steep decline in abundance with increasing redshift. However, the LF is a convolution of the mass function of dark matter halos (HMF) — which also declines sharply over this redshift range — and the galaxy-formation physics that maps halo mass to galaxy luminosity. We consider the strong observed evolution in the LF from z ≈ 6–10 in this context and determine whether it can be explained solely by the behavior of the HMF. From z ≈ 6–8, we find a residual change in the physics of galaxy formation corresponding to a ∼ 0.5 dex increase in the average luminosity of a halo of fixed mass. On the other hand, our analysis of recent LF measurements at z ≈ 10 shows that the paucity of detected galaxies is consistent with almost no change in the average luminosity at fixed halo mass from z ≈ 8. The LF slope also constrains the variation about this mean such that the luminosity of galaxies hosted by halos of the same mass are all within about an order-of-magnitude of each other. We show that these results are well-described by a simple model of galaxy formation in which cold-flow accretion is balanced by star formation and momentum-driven outflows. If galaxy formation proceeds in halos with masses down to 108Msun, then such a model predicts that LBGs at z ≈ 10 should be able to maintain an ionized intergalactic medium as long as the ratio of the clumping factor to the ionizing escape fraction is C/fesc∼<10

  15. A molecular line scan in the Hubble deep field north: Constraints on the co luminosity function and the cosmic H2 density

    International Nuclear Information System (INIS)

    We present direct constraints on the CO luminosity function at high redshift and the resulting cosmic evolution of the molecular gas density, ρH2(z), based on a blind molecular line scan in the Hubble Deep Field North (HDF-N) using the IRAM Plateau de Bure Interferometer. Our line scan of the entire 3 mm window (79-115 GHz) covers a cosmic volume of ∼7000 Mpc3, and redshift ranges z < 0.45, 1.01 < z < 1.89 and z > 2. We use the rich multiwavelength and spectroscopic database of the HDF-N to derive some of the best constraints on CO luminosities in high redshift galaxies to date. We combine the blind CO detections in our molecular line scan (presented in a companion paper) with stacked CO limits from galaxies with available spectroscopic redshifts (slit or mask spectroscopy from Keck and grism spectroscopy from the Hubble Space Telescope) to give first blind constraints on high-z CO luminosity functions and the cosmic evolution of the H2 mass density ρH2(z) out to redshifts z ∼ 3. A comparison to empirical predictions of ρH2(z) shows that the securely detected sources in our molecular line scan already provide significant contributions to the predicted ρH2(z) in the redshift bins (z) ∼ 1.5 and (z) ∼ 2.7. Accounting for galaxies with CO luminosities that are not probed by our observations results in cosmic molecular gas densities ρH2(z) that are higher than current predictions. We note, however, that the current uncertainties (in particular the luminosity limits, number of detections, as well as cosmic volume probed) are significant, a situation that is about to change with the emerging ALMA observatory.

  16. Mass-loss rates and luminosity functions of dust-enshrouded AGB stars and red supergiants in the LMC

    CERN Document Server

    Van Loon, J T; De Koter, A; Trams, N R; Waters, L B F M; Zijlstra, A A; Whitelock, P A; Loup, C; Loon, Jacco Th. van; Trams, Norman R.; Zijlstra, Albert A.; Whitelock, Patricia A.; Loup, Cecile

    1999-01-01

    A radiative transfer code is used to model the spectral energy distributions of 57 mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC) for which ISO spectroscopic and photometric data are available. As a result we derive mass-loss rates and bolometric luminosities. A gap in the luminosity distribution around M_bol = -7.5 mag separates AGB stars from RSGs. The luminosity distributions of optically bright carbon stars, dust-enshrouded carbon stars and dust-enshrouded M-type stars have only little overlap, suggesting that the dust-enshrouded AGB stars are at the very tip of the AGB and will not evolve significantly in luminosity before mass loss ends their AGB evolution. Derived mass-loss rates span a range from Mdot about 10^-7 to 10^-3 M_sun/yr. More luminous and cooler stars are found to reach higher mass-loss rates. The highest mass-loss rates exceed the classical limit set by the momentum of the stellar radiation field, L/c, by a factor of a few due...

  17. The bulge-disc decomposition of AGN host galaxies

    Science.gov (United States)

    Bruce, V. A.; Dunlop, J. S.; Mortlock, A.; Kocevski, D. D.; McGrath, E. J.; Rosario, D. J.

    2016-05-01

    We present the results from a study of the morphologies of moderate luminosity X-ray-selected active galactic nuclei (AGN) host galaxies in comparison to a carefully mass-matched control sample at 0.5 hosts are by a potential nuclear contribution from the AGN itself. We find that the AGN hosts are indistinguishable from the general galaxy population except that beyond z ≃ 1.5 they have significantly higher bulge fractions. Even including nuclear sources in our modelling, the probability of this result arising by chance is ˜1 × 10-5, alleviating concerns that previous, purely single Sérsic, analyses of AGN hosts could have been spuriously biased towards higher bulge fractions. This data set also allows us to further probe the physical nature of these point-source components; we find no strong correlation between the point-source component and AGN activity. Our analysis of the bulge and disc fractions of these AGN hosts in comparison to a mass-matched control sample reveals a similar morphological evolutionary track for both the active and non-active populations, providing further evidence in favour of a model where AGN activity is triggered by secular processes.

  18. Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria

    CERN Document Server

    Donley, J L; Brusa, M; Capak, P; Cardamone, C N; Civano, F; Ilbert, O; Impey, C D; Kartaltepe, J S; Miyaji, T; Salvato, M; Sanders, D B; Trump, J R; Zamorani, G

    2012-01-01

    Spitzer IRAC selection is a powerful tool for identifying luminous AGN. For deep IRAC data, however, the AGN selection wedges currently in use are heavily contaminated by star-forming galaxies, especially at high redshift. Using the large samples of luminous AGN and high-redshift star-forming galaxies in COSMOS, we redefine the AGN selection criteria for use in deep IRAC surveys. The new IRAC criteria are designed to be both highly complete and reliable, and incorporate the best aspects of the current AGN selection wedges and of infrared power-law selection while excluding high redshift star-forming galaxies selected via the BzK, DRG, LBG, and SMG criteria. At QSO-luminosities of log L(2-10 keV) (ergs/s) > 44, the new IRAC criteria recover 75% of the hard X-ray and IRAC-detected XMM-COSMOS sample, yet only 38% of the IRAC AGN candidates have X-ray counterparts, a fraction that rises to 52% in regions with Chandra exposures of 50-160 ks. X-ray stacking of the individually X-ray non-detected AGN candidates lead...

  19. Signatures of AGN feedback

    Science.gov (United States)

    Wylezalek, D.; Zakamska, N.

    2016-06-01

    Feedback from active galactic nuclei (AGN) is widely considered to be the main driver in regulating the growth of massive galaxies. It operates by either heating or driving the gas that would otherwise be available for star formation out of the galaxy, preventing further increase in stellar mass. Observational proof for this scenario has, however, been hard to come by. We have assembled a large sample of 133 radio-quiet type-2 and red AGN at 0.1importantly, we find a negative correlation between W_{90} and sSFR in the AGN hosts with the highest star formation rates, i.e., with the highest gas content. This relationship implies that AGN with strong outflow signatures are hosted in galaxies that are more `quenched' considering their stellar mass than galaxies with weaker outflow signatures. This correlation is only seen in AGN host galaxies with SFR >100 M_{⊙} yr^{-1} where presumably the coupling of the AGN-driven wind to the gas is strongest. This observation is consistent with the AGN having a net suppression, or `negative' impact, through feedback on the galaxies' star formation history.

  20. The X-ray Zurich Environmental Study (X-ZENS). I. Chandra and XMM-Newton observations of AGNs in galaxies in nearby groups

    CERN Document Server

    Silverman, J D; Finoguenov, A; Carollo, C M; Cibinel, A; Lilly, S J; Schawinski, K

    2013-01-01

    We describe X-ray observations with Chandra and XMM-Newton of 18 galaxy groups (M_group ~ 1-6x10^13 Msolar, z~0.05) from the Zurich Environmental Study (ZENS). We aim to establish the frequency and properties, unaffected by host galaxy dilution and obscuration, of AGNs in central and satellite galaxy members, also as a function of halo-centric distance. X-ray point-source detections are reported for 22 of 177 observed galaxies, down to a limit of f_(0.5-8 keV) ~ 5x10^-15 erg cm^-2 s^-1, corresponding to a limiting luminosity of L_(0.5-8 keV)~3x10^40 erg s^-1. With the majority of the X-ray sources attributed to AGNs of low-to-moderate levels (L/L_Edd>~10^-4), we discuss the detection rate in the context of the occupation of AGNs to halos of this mass scale and redshift, and compare the structural/morphological properties between AGN-active and non-active galaxies of different rank and location within the group halos. We see a slight tendency for AGN hosts to have either relatively brighter/denser disks (or re...

  1. Extracting Information from AGN Variability

    CERN Document Server

    Kasliwal, Vishal P; Richards, Gordon T

    2016-01-01

    AGN exhibit rapid, high amplitude stochastic flux variability across the entire electromagnetic spectrum on timescales ranging from hours to years. The cause of this variability is poorly understood. We present a new method for using variability to (1) measure the time-scales on which flux perturbations evolve and (2) characterize the driving flux perturbations. We model the observed light curve of an AGN as a linear differential equation driven by stochastic impulses. Physically, the impulses could be local `hot-spots' in the accretion disk---the linear differential equation then governs how the hot spots evolve and dissipate. The impulse-response function of the accretion disk material is given by the Green's function of the linear differential equation. The timescales on which the hot-spots radiate energy is characterized by the powerspectrum of the driving stochastic impulses. We analyze the light curve of the \\Kepler AGN Zw 229-15 and find that the observed variability behavior can be modeled as a damped...

  2. VLT-FORS2 optical imaging and spectroscopy of 9 luminous type 2 AGN at 0.3

    CERN Document Server

    Humphrey, A; Almeida, C Ramos; Tadhunter, C N; Arribas, S; Bessiere, P S; Cabrera-Lavers, A

    2015-01-01

    We present optical imaging and long slit spectroscopic observations of 9 luminous type 2 AGNs within the redshift range 0.3luminosity Seyfert 2, and three are type 2 quasars (QSO2), with our sample extending to lower luminosity than previous works. Seven out of nine objects (78%) show morphological evidence for interactions or mergers in the form of disturbed morphologies and/or peculiar features such as tidal tails, amorphous halos, or compact emission line knots. The detection rate of morphological evidence for interaction is consistent with those found during previous studies of QSO2 at similar z, suggesting that the merger rate is independent of AGN power at the high end of the AGN luminosity function. We find the emission line flux spatial profiles are often dominated by the often spatially unresolved central source. In addition, all but one of our sample is associated with much fainter, extended line emission. We find these extended emiss...

  3. The luminosity function of star clusters in 20 star-forming galaxies based on Hubble legacy archive photometry

    International Nuclear Information System (INIS)

    Luminosity functions (LFs) have been determined for star cluster populations in 20 nearby (4-30 Mpc), star-forming galaxies based on Advanced Camera for Surveys source lists generated by the Hubble Legacy Archive (HLA). These cluster catalogs provide one of the largest sets of uniform, automatically generated cluster candidates available in the literature at present. Comparisons are made with other recently generated cluster catalogs demonstrating that the HLA-generated catalogs are of similar quality, but in general do not go as deep. A typical cluster LF can be approximated by a power law, dN/dL∝L α, with an average value for α of –2.37 and rms scatter = 0.18 when using the F814W ('I') band. A comparison of fitting results based on methods that use binned and unbinned data shows good agreement, although there may be a systematic tendency for the unbinned (maximum likelihood) method to give slightly more negative values of α for galaxies with steeper LFs. We find that galaxies with high rates of star formation (or equivalently, with the brightest or largest numbers of clusters) have a slight tendency to have shallower values of α. In particular, the Antennae galaxy (NGC 4038/39), a merging system with a relatively high star formation rate (SFR), has the second flattest LF in the sample. A tentative correlation may also be present between Hubble type and values of α, in the sense that later type galaxies (i.e., Sd and Sm) appear to have flatter LFs. Hence, while there do appear to be some weak correlations, the relative similarity in the values of α for a large number of star-forming galaxies suggests that, to first order, the LFs are fairly universal. We examine the bright end of the LFs and find evidence for a downturn, although it only pertains to about 1% of the clusters. Our uniform database results in a small scatter (≈0.4 to 0.5 mag) in the correlation between the magnitude of the brightest cluster (M brightest) and log of the number of

  4. The luminosity function of star clusters in 20 star-forming galaxies based on Hubble legacy archive photometry

    Energy Technology Data Exchange (ETDEWEB)

    Whitmore, Bradley C.; Bowers, Ariel S.; Lindsay, Kevin; Ansari, Asna; Evans, Jessica [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Chandar, Rupali [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Larsen, Soeren, E-mail: whitmore@stsci.edu [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P. O. Box 9010, 6500 GL Nijmegen (Netherlands)

    2014-04-01

    Luminosity functions (LFs) have been determined for star cluster populations in 20 nearby (4-30 Mpc), star-forming galaxies based on Advanced Camera for Surveys source lists generated by the Hubble Legacy Archive (HLA). These cluster catalogs provide one of the largest sets of uniform, automatically generated cluster candidates available in the literature at present. Comparisons are made with other recently generated cluster catalogs demonstrating that the HLA-generated catalogs are of similar quality, but in general do not go as deep. A typical cluster LF can be approximated by a power law, dN/dL∝L {sup α}, with an average value for α of –2.37 and rms scatter = 0.18 when using the F814W ('I') band. A comparison of fitting results based on methods that use binned and unbinned data shows good agreement, although there may be a systematic tendency for the unbinned (maximum likelihood) method to give slightly more negative values of α for galaxies with steeper LFs. We find that galaxies with high rates of star formation (or equivalently, with the brightest or largest numbers of clusters) have a slight tendency to have shallower values of α. In particular, the Antennae galaxy (NGC 4038/39), a merging system with a relatively high star formation rate (SFR), has the second flattest LF in the sample. A tentative correlation may also be present between Hubble type and values of α, in the sense that later type galaxies (i.e., Sd and Sm) appear to have flatter LFs. Hence, while there do appear to be some weak correlations, the relative similarity in the values of α for a large number of star-forming galaxies suggests that, to first order, the LFs are fairly universal. We examine the bright end of the LFs and find evidence for a downturn, although it only pertains to about 1% of the clusters. Our uniform database results in a small scatter (≈0.4 to 0.5 mag) in the correlation between the magnitude of the brightest cluster (M {sub brightest}) and log of

  5. The 2dF-SDSS LRG and QSO Survey: The z<2.1 Quasar Luminosity Function from 5645 Quasars to g=21.85

    CERN Document Server

    Richards, G T; Anderson, S F; Bland-Hawthorn, J; Boyle, B J; De Propris, R; Drinkwater, M J; Fan, X; Gunn, J E; Ivezic, Z; Jester, S; Loveday, J; Meiksin, A; Miller, L; Myers, A; Nichol, R C; Outram, P J; Pimbblet, K A; Roseboom, I G; Ross, N; Schneider, D P; Shanks, T; Sharp, R G; Stoughton, C; Strauss, M A; Szalay, A S; Vanden Berk, Daniel E; York, D G

    2005-01-01

    We have used the 2dF instrument on the AAT to obtain redshifts of a sample of z21 deep surveys. The 2SLAQ data exhibit no well defined ``break'' but do clearly flatten with increasing magnitude. The shape of the quasar luminosity function derived from 2SLAQ is in good agreement with that derived from type I quasars found in hard X-ray surveys. [Abridged

  6. Dichotomy in host environments and signs of recycled AGN

    CERN Document Server

    Coldwell, Georgina V; Soechting, Ilona K; Gurovich, Sebastian

    2009-01-01

    We analyse the relation between AGN host properties and large scale environment for a representative red and blue AGN host galaxy sample selected from the DR4 SDSS. A comparison is made with two carefully constructed control samples of non-active galaxies, covering the same redshift range and color baseline. The cross-correlation functions show that the density distribution of neighbours is almost identical for blue galaxies, either active, or non-active. Although active red galaxies inhabit environments less dense compared to non-active red galaxies, both reside in environments considerably denser than those of blue hosts. Moreover, the radial density profile of AGN, relative to galaxy group centres is less concentrated than galaxies. This is particularly evident when comparing red AGN and non-active galaxies. The properties of the neighbouring galaxies of blue and red AGN and non active galaxies reflect this effect. While the neighbourhood of the blue samples is indistinguishable, the red AGN environs show ...

  7. IMPACT OF H2-BASED STAR FORMATION MODEL ON THE z ≥ 6 LUMINOSITY FUNCTION AND THE IONIZING PHOTON BUDGET FOR REIONIZATION

    International Nuclear Information System (INIS)

    We present the results of a numerical study examining the effect of an H2-based star formation (SF) model on the rest-frame UV luminosity function and star formation rate function (SFRF) of z ≥ 6 galaxies, and the implications for reionization. Using cosmological hydrodynamical simulations outfitted with an H2-SF model, we find good agreement with our previous results (non-H2 SF model) and observations at Muv ≤ –18. However, at Muv > –18, we find that the LF deviates from both our previous work and current observational extrapolations, producing significantly fewer low-luminosity galaxies and exhibiting additional turnover at the faint end. We constrain the redshift evolution of this turnover point using a modified Schechter function that includes additional terms to quantify the turnover magnitude (Muvt) and subsequent slope (β). We find that Muvt evolves from Muvt=-17.33 (at z = 8) to –15.38 (z = 6), while β becomes shallower by Δβ = 0.22 during the same epoch. This occurs in an Muv range that will be observable by James Webb Space Telescope. By integrating the SFRF, we determine that even though the H2-SF model significantly reduces the number density of low-luminosity galaxies at Muv > –18, it does not suppress the total SFR density enough to affect the capability of SF to maintain reionization.

  8. On the properties of galaxies at the faint-end of the H$\\alpha$ luminosity function at $z\\sim0.62$

    CERN Document Server

    Gómez-Guijarro, Carlos; Villar, Víctor; Rodríguez-Muñoz, Lucía; Clément, Benjamin; Cuby, Jean-Gabriel

    2016-01-01

    Studies measuring the star formation rate density, luminosity function and properties of star-forming galaxies are numerous. However, it exists a gap at $0.5luminosity function and derived star formation rate density, characterising their morphologies and basic photometric and spectroscopic properties. We use a narrow-band technique in the near-infrared, with a filter centered at 1.06 $\\mu$m. The data come from ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9 h in the narrow-band filter. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. Our 28 H$\\alpha$-selected sample of faint star-forming galaxies reveals a robust faint-end slope of the luminosity function $\\alpha=-1.46_{-0.08}^{+0.16}$. The derived star formation...

  9. Decoding spectral energy distributions of dust-obscured starburst-AGN

    CERN Document Server

    Han, Yunkun

    2012-01-01

    We present BayeSED, a general purpose tool for doing Bayesian analysis of SEDs by using whatever pre-existing model SED libraries or their linear combinations. The artificial neural networks (ANNs), principal component analysis (PCA) and multimodal nested sampling (MultiNest) techniques are employed to allow a highly efficient sampling of posterior distribution and the calculation of Bayesian evidence. As a demonstration, we apply this tool to a sample of hyperluminous infrared galaxies (HLIRGs). The Bayesian evidences obtained for a pure Starburst, a pure AGN, and a linear combination of Starburst+AGN models show that the Starburst+AGN model have the highest evidence for all galaxies in this sample. The Bayesian evidences for the three models and the estimated contributions of starburst and AGN to infrared luminosity show that HLIRGs can be classified into two groups: one dominated by starburst and the other dominated by AGN. Other parameters and corresponding uncertainties about starburst and AGN are also e...

  10. Investigating the Disk-Corona Relation in a Blue AGN Sample

    OpenAIRE

    Liu, Jie-Ying; Liu, B.F.

    2009-01-01

    We compile a blue AGN sample from SDSS and investigate the ratio of hard X-ray to bolometric luminosity in dependence on Eddington ratio and black hole mass. Our sample comprises 240 radio-quiet Seyfert 1 galaxies and QSOs. We find that the fraction of hard X-ray luminosity (log$(L_{\\rm 2-10 kev}/L_{\\rm bol})$) decreases with the increase of Eddington ratio. We also find that the fraction of hard X-ray luminosity is independent on the black hole mass for the radio-quiet AGNs. The relation of ...

  11. The X-ray luminosity function of low mass X-ray binaries in early-type galaxies, their metal-rich, and metal-poor globular clusters

    CERN Document Server

    Peacock, Mark B

    2015-01-01

    We present the X-ray luminosity function (XLF) of low mass X-ray binaries (LMXBs) in the globular clusters (GCs) and fields of seven early-types galaxies. These galaxies are selected to have both deep Chandra observations, which allow their LMXB populations to be observed to X-ray luminosities of $10^{37}-10^{38}$ erg/s, and HST optical mosaics which enable the X-ray sources to be separated into field LMXBs, GC LMXBs, and contaminating background and foreground sources. We find that at all luminosities the number of field LMXBs per stellar mass is similar in these galaxies. This suggests that the field LMXB populations in these galaxies are not effected by the GC specific frequency, and that properties such as binary fraction and the stellar initial mass function are either similar across the sample, or change in a way that does not effect the number of LMXBs. We compare the XLF of the field LMXBs to that of the GC LMXBs and find that they are significantly different with a p-value of $3\\times10^{-6}$ (equiva...

  12. The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of the faint end: implications for reionization

    CERN Document Server

    Santos, Sérgio; Matthee, Jorryt

    2016-01-01

    We present new results from the widest narrow band survey search for Lyman-alpha (Lya) emitters at z=5.7, just after reionization. We survey a total of 7 deg$^2$ spread over the COSMOS, UDS and SA22 fields. We find over 11,000 line emitters, out of which 514 are robust Lya candidates at z=5.7 within a volume of 6.3x10$^6$ Mpc$^3$. Our Lya emitters span a wide range in Lya luminosities, from faint to bright (L$_{\\rm Ly\\alpha}\\sim10^{42.5-44}$ erg s$^{-1}$) and rest-frame equivalent widths (EW$_0$~25-1000 \\AA) in a single, homogeneous data-set. By combining all our fields we find that the faint end slope of the z=5.7 Lya luminosity function is very steep, with $\\alpha=-2.3^{+0.4}_{-0.3}$. We also present an updated z=6.6 Lya luminosity function, based on comparable volumes and obtained with the same methods, which we directly compare with that at z=5.7. We find a significant decline of the number density of faint Lya emitters from z=5.7 to z=6.6 (by $0.5\\pm0.1$ dex), but no evolution at the bright end/no evolut...

  13. A Molecular Line Scan in the Hubble Deep Field North: Constraints on the CO Luminosity Function and the Cosmic H2 Density

    CERN Document Server

    Walter, F; Sargent, M; Carilli, C; Dickinson, M; Riechers, D; Ellis, R; Stark, D; Weiner, B; Aravena, M; Bell, E; Bertoldi, F; Cox, P; Da Cunha, E; Daddi, E; Downes, D; Lentati, L; Maiolino, R; Menten, K M; Neri, R; Rix, H W; Weiss, A

    2013-01-01

    We present direct constraints on the CO luminosity function at high redshift and the resulting cosmic evolution of the molecular gas density, $\\rho_{\\rm H2}$(z), based on a blind molecular line scan in the Hubble Deep Field North (HDF-N) using the IRAM Plateau de Bure Interferometer. Our line scan of the entire 3mm window (79-115 GHz) covers a cosmic volume of ~7000 Mpc$^3$, and redshift ranges z2. We use the rich multiwavelength and spectroscopic database of the HDF-N to derive some of the best constraints on CO luminosities in high redshift galaxies to date. We combine the blind CO detections in our molecular line scan (presented in a companion paper) with stacked CO limits from galaxies with available spectroscopic redshifts (slit or mask spectroscopy from Keck and grism spectroscopy from HST) to give first blind constraints on high-z CO luminosity functions and the cosmic evolution of the H2 mass density $\\rho_{\\rm H2}$(z) out to redshifts z~3. A comparison to empirical predictions of $\\rho_{\\rm H2}$(z) s...

  14. Constraining the X-ray AGN halo occupation distribution: implications for eROSITA

    CERN Document Server

    Singh, Priyanka; Majumdar, Subhabrata; Nath, Biman B

    2016-01-01

    The X-ray emission from active galactic nucleus (AGN) is a major component of extragalactic X-ray sky. In this paper, we use the X-ray luminosity function (XLF) and halo occupation distribution (HOD) formalism to construct a halo model for the X-ray emission from AGNs. Verifying that the two inputs (XLF and HOD) are in agreement with each other, we compute the auto-correlation power spectrum in the soft X-ray band (0.5-2 kev) due to the AGNs potentially resolved by eROSITA mission and explore the redshift and mass dependence of the power spectrum. Studying the relative contribution of the Poisson and the clustering terms to the total power, we find that at multipoles $l\\lesssim 1000$ (i.e. large scales), the clustering term is larger than the Poisson term. We also forecast the potential of X-ray auto-correlation power spectrum and X-ray-lensing cross-correlation power spectrum using eROSITA and eROSITA-LSST surveys, respectively, to constrain the HOD parameters and their redshift evolution. In addition, we co...

  15. The Next Generation Virgo Cluster Survey (NGVS). XIII. The Luminosity and Mass Function of Galaxies in the Core of the Virgo Cluster and the Contribution from Disrupted Satellites

    Science.gov (United States)

    Ferrarese, Laura; Côté, Patrick; Sánchez-Janssen, Rúben; Roediger, Joel; McConnachie, Alan W.; Durrell, Patrick R.; MacArthur, Lauren A.; Blakeslee, John P.; Duc, Pierre-Alain; Boissier, S.; Boselli, Alessandro; Courteau, Stéphane; Cuillandre, Jean-Charles; Emsellem, Eric; Gwyn, S. D. J.; Guhathakurta, Puragra; Jordán, Andrés; Lançon, Ariane; Liu, Chengze; Mei, Simona; Mihos, J. Christopher; Navarro, Julio F.; Peng, Eric W.; Puzia, Thomas H.; Taylor, James E.; Toloba, Elisa; Zhang, Hongxin

    2016-06-01

    We present measurements of the galaxy luminosity and stellar mass function in a 3.71 deg2 (0.3 Mpc2) area in the core of the Virgo Cluster, based on {u}\\ast griz data from the Next Generation Virgo Cluster Survey (NGVS). The galaxy sample—which consists of 352 objects brighter than M g = ‑9.13 mag, the 50% completeness limit of the survey—reaches 2.2 mag deeper than the widely used Virgo Cluster Catalog and at least 1.2 mag deeper than any sample previously used to measure the luminosity function in Virgo. Using a Bayesian analysis, we find a best-fit faint-end slope of α = ‑1.33 ± 0.02 for the g-band luminosity function; consistent results are found for the stellar mass function and the luminosity function in the other four NGVS bandpasses. We discuss the implications for the faint-end slope of adding 92 ultracompact dwarfs (UCDs)—previously compiled by the NGVS in this region—to the galaxy sample, assuming that UCDs are the stripped remnants of nucleated dwarf galaxies. Under this assumption, the slope of the luminosity function (down to the UCD faint magnitude limit, M g = ‑9.6 mag) increases dramatically, up to α = ‑1.60 ± 0.06 when correcting for the expected number of disrupted non-nucleated galaxies. We also calculate the total number of UCDs and globular clusters that may have been deposited in the core of Virgo owing to the disruption of satellites, both nucleated and non-nucleated. We estimate that ∼150 objects with M g ≲ ‑9.6 mag and that are currently classified as globular clusters might, in fact, be the nuclei of disrupted galaxies. We further estimate that as many as 40% of the (mostly blue) globular clusters in the Virgo core might once have belonged to such satellites; these same disrupted satellites might have contributed ∼40% of the total luminosity in galaxies observed in the core region today. Finally, we use an updated Local Group galaxy catalog to provide a new measurement of the luminosity function of Local Group

  16. AGN outflow feedback: Constraints from variability

    CERN Document Server

    Detmers, R G

    2009-01-01

    We present an overview on how variability can be used to constrain the location of the ionized outflow in nearby Active Galactic Nuclei using high-resolution X-ray spectroscopy. Without these constraints on the location of the outflow, the kinetic luminosity and mass loss rate can not be determined. We focus on the Seyfert 1 galaxy NGC 5548, which is arguably the best studied AGN on a timescale of 10 years. Our results show that frequent observations combined with long term monitoring, such as with the \\textit{Rossi X-ray Timing Explorer (RXTE)} satellite, are crucial to investigate the effects of these outflows on their surroundings.

  17. EVERY BCG WITH A STRONG RADIO AGN HAS AN X-RAY COOL CORE: IS THE COOL CORE-NONCOOL CORE DICHOTOMY TOO SIMPLE?

    International Nuclear Information System (INIS)

    The radio active galactic nucleus (AGN) feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in 'noncool core' clusters, which brings up the question whether an X-ray cool core is always required for the radio feedback. In this work, we present a systematic analysis of brightest cluster galaxies (BCGs) and strong radio AGNs in 152 groups and clusters from the Chandra archive. All 69 BCGs with radio AGN more luminous than 2 x 1023 W Hz-1 at 1.4 GHz are found to have X-ray cool cores. BCG cool cores can be divided into two classes: the large cool core (LCC) class and the corona class. Small coronae, easily overlooked at z > 0.1, can trigger strong heating episodes in groups and clusters, long before LCCs are formed. Strong radio outbursts triggered by coronae may destroy embryonic LCCs and thus provide another mechanism to prevent the formation of LCCs. However, it is unclear whether coronae are decoupled from the radio feedback cycles as they have to be largely immune to strong radio outbursts. Our sample study also shows the absence of groups with a luminous cool core while hosting a strong radio AGN, which is not observed in clusters. This points to a greater impact of radio heating on low-mass systems than clusters. Few L 1.4GHz > 1024 W Hz-1 radio AGNs (∼16%) host an L 0.5-10keV > 1042 erg s-1 X-ray AGN, while above these thresholds, all X-ray AGNs in BCGs are also radio AGNs. As examples of the corona class, we also present detailed analyses of a BCG corona associated with a strong radio AGN (ESO 137-006 in A3627) and one of the faintest coronae known (NGC 4709 in the Centaurus cluster). Our results suggest that the traditional cool core/noncool core dichotomy is too simple. A better alternative is the cool core distribution function, with the enclosed X-ray luminosity or gas mass.

  18. Constraining the properties of AGN host galaxies with Spectral Energy Distribution modeling

    CERN Document Server

    Ciesla, L; Georgakakis, A; Bernhard, E; Mitchell, P D; Buat, V; Elbaz, D; Floc'h, E Le; Lacey, C G; Magdis, G E; Xilouris, M

    2015-01-01

    [abridged] We use the latest release of CIGALE, a galaxy SED fitting model relying on energy balance, to study the influence of an AGN in estimating both the SFR and stellar mass in galaxies, as well as the contribution of the AGN to the power output of the host. Using the galaxy formation SAM GALFORM, we create mock galaxy SEDs using realistic star formation histories (SFH) and add an AGN of Type 1, Type 2, or intermediate type whose contribution to the bolometric luminosity can be variable. We perform an SED fitting of these catalogues with CIGALE assuming three different SFHs: a single- and double-exponentially-decreasing, and a delayed SFH. Constraining thecontribution of an AGN to the LIR (fracAGN) is very challenging for fracAGN<20%, with uncertainties of ~5-30% for higher fractions depending on the AGN type, while FIR and sub-mm are essential. The AGN power has an impact on the estimation of $M_*$ in Type 1 and intermediate type AGNs but has no effect for galaxies hosting Type 2 AGNs. We find that i...

  19. On the Reliability of Cross Correlation Function Lag Determinations in Active Galactic Nuclei

    CERN Document Server

    Welsh, W F

    1999-01-01

    Many AGN exhibit a highly variable luminosity. Some AGN also show a pronounced time delay between variations seen in their optical continuum and in their emission lines. In effect, the emission lines are light echoes of the continuum. This light travel-time delay provides a characteristic radius of the region producing the emission lines. The cross correlation function (CCF) is the standard tool used to measure the time lag between the continuum and line variations. For the few well-sampled AGN, the lag ranges from 1-100 days, depending upon which line is used and the luminosity of the AGN. In the best sampled AGN, NGC 5548, the H_beta lag shows year-to-year changes, ranging from about 8.7 days to about 22.9 days over a span of 8 years. In this paper it is demonstrated that, in the context of AGN variability studies, the lag estimate using the CCF is biased too low and subject to a large variance. Thus the year-to-year changes of the measured lag in NGC 5548 do not necessarily imply changes in the AGN structu...

  20. On the Lx-L6micron ratio as a diagnostic for Compton-thick AGN

    CERN Document Server

    Georgantopoulos, I; Akylas, A; Comastri, A; Ranalli, P; Vignali, C; Balestra, I; Gilli, R; Cappelluti, N

    2011-01-01

    As the mid-IR luminosity represents a good isotropic proxy of the AGN power, a low X-ray to mid-IR luminosity ratio is often claimed to be a reliable indicator for selecting Compton-thick (CT) AGN. We assess the efficiency of this diagnostic by examining the 12mu IRAS AGN sample for which high signal-to-noise XMM observations have been recently become available. We find that the vast majority (10/11) of the AGN that have been classified as CT on the basis the X-ray spectroscopy by Brightman & Nandra present a low Lx/L6 luminosity ratio, i.e. lower than a few percent of the average AGN ratio which is typical of reflection-dominated CT sources. At low Lx/L6 ratios we also find a comparable number of AGN, most of which are heavily absorbed but not CT. This implies that although most Compton-thick AGN present low Lx/L6 ratios, at least in the local, Universe, the opposite is not necessarily true. Next, we extend our analysis to higher redshifts. We perform the same analysis in the CDFS where excellent quality...

  1. Environmental dependence of AGN activity. I.: the effects of host galaxy

    CERN Document Server

    Choi, Yun-Young; Park, Changbum

    2009-01-01

    Using a large sample of local galaxies (144,940) with -17.5 6. We find that the fraction of galaxies hosting an AGN (f_AGN) depends strongly on morphology together with color, and very weakly on luminosity or velocity dispersion of host galaxies. In particular, f_AGN of early-type galaxies is almost independent of luminosity nor velocity dispersion when color is fixed. The host galaxy color preferred by AGNs is u-r ~2.0 for early-type hosts and u-r=2.0-2.4 for late-type hosts. This trend suggests that AGNs are dominantly hosted by intermediate-mass late-type galaxies. We also investigate how the accretion power varies with galaxy properties. While the Eddington ratio ([OIII] line luminosity normalized by black hole mass) ranges over three orders of magnitude for both morphological types, late-type galaxies are the dominant hosts over all AGN power. Among late-type galaxies, bluer color galaxies host higher power AGNs. These results are consistent with a scenario that more massive and redder galaxies are harde...

  2. The Chandra COSMOS Legacy Survey: Clustering of X-ray selected AGN at 2.9Functions

    CERN Document Server

    Allevato, V; Finoguenov, A; Marchesi, S; Zamorani, G; Hasinger, G; Salvato, M; Miyaji, T; Gilli, R; Cappelluti, N; Brusa, M; Suh, H; Lanzuisi, G; Trakhtenbrot, B; Griffiths, R; Vignali, C; Schawinski, K; Karim, A

    2016-01-01

    We present the measurement of the projected and redshift space 2-point correlation function (2pcf) of the new catalog of Chandra COSMOS-Legacy AGN at 2.9$\\leq$z$\\leq$5.5 ($\\langle L_{bol} \\rangle \\sim$10$^{46}$ erg/s) using the generalized clustering estimator based on phot-z probability distribution functions (Pdfs) in addition to any available spec-z. We model the projected 2pcf estimated using $\\pi_{max}$ = 200 h$^{-1}$ Mpc with the 2-halo term and we derive a bias at z$\\sim$3.4 equal to b = 6.6$^{+0.60}_{-0.55}$, which corresponds to a typical mass of the hosting halos of log M$_h$ = 12.83$^{+0.12}_{-0.11}$ h$^{-1}$ M$_{\\odot}$. A similar bias is derived using the redshift-space 2pcf, modelled including the typical phot-z error $\\sigma_z$ = 0.052 of our sample at z$\\geq$2.9. Once we integrate the projected 2pcf up to $\\pi_{max}$ = 200 h$^{-1}$ Mpc, the bias of XMM and \\textit{Chandra} COSMOS at z=2.8 used in Allevato et al. (2014) is consistent with our results at higher redshift. The results suggest only...

  3. The Relationship between black hole accretion and host star formation in dusty AGNs

    CERN Document Server

    Dai, Y Sophia; Bergeron, Jacqueline; Omont, Alain; Kuraszkiewicz, Joanna; Teplitz, Harry I

    2015-01-01

    We study the relationship between the X-ray luminosity and star formation rate (SFR) in an unbiased sample of dusty active galactic nuclei (AGNs), detected in both the hard X-ray and far-infrared (IR) bands in the XMM-LSS field. The sample consists of 451 AGNs with spectroscopic redshifts of 0.04 < z <3.3, and spans an X-ray luminosity range of L(2-10keV)=10^41-45 erg/s. We find a positive correlation between the X-ray luminosity and SFR derived from AGN-removed IR luminosity. We find that binning the sample by SFR instead of LX results in a more positive correlation. This is consistent with the scenario in which the shorter variability time scale of AGN than star formation flattens the observed correlation between AGN and star formation. We do not find significant diversity in the observed correlation when considering subsets selected based on supermassive black hole mass or Eddington ratio, indicating that AGN accretion has at most a limited effect on the SFR-Lx relation. Comparing to results in the l...

  4. The evolution of the near-infrared galaxy luminosity function and colour bimodality up to z ~= 2 from the UKIDSS Ultra Deep Survey Early Data Release

    Science.gov (United States)

    Cirasuolo, M.; McLure, R. J.; Dunlop, J. S.; Almaini, O.; Foucaud, S.; Smail, Ian; Sekiguchi, K.; Simpson, C.; Eales, S.; Dye, S.; Watson, M. G.; Page, M. J.; Hirst, P.

    2007-09-01

    We present new results on the cosmological evolution of the near-infrared (near-IR) galaxy luminosity function (LF), derived from the analysis of a new sample of ~22000KAB Ultra Deep Survey (UDS). Our study has exploited the multiwavelength coverage of the UDS field provided by the new UKIDSS WFCAM K- and J-band imaging, the Subaru/XMM-Newton Deep Survey and the Spitzer Wide-Area Infrared Extragalactic survey. The unique combination of large area and depth provided by this new survey minimizes the complicating effect of cosmic variance and has allowed us, for the first time, to trace the evolution of the brightest sources out to z ~= 2 with good statistical accuracy. In agreement with previous studies, we find that the characteristic luminosity of the near-IR LF brightens by ~=1 mag between z = 0 and z ~= 2, while the total density decreases by a factor of ~=2. Using the rest-frame (U - B) colour to split the sample into red and blue galaxies, we confirm the classic luminosity-dependent colour bimodality at z ~ 1.5. Due to the large size of our sample, we are able to investigate the differing cosmological evolution of the red and blue galaxy populations. It is found that the space density of the brightest red galaxies (MK ~ 1.

  5. Supermassive Black Holes, AGN Feedback, and Hot X-ray Coronae in Early Type Galaxies

    Science.gov (United States)

    Forman, William R.; Anderson, Michael E.; Churazov, Eugene; Nulsen, Paul; Jones, Christine; Kraft, Ralph P.

    2016-06-01

    We present the analysis of a sample of more than 200 nearby, early type galaxies observed with the Chandra X-ray Observatory. We exclude resolved point sources, and model the emission from both unresolved X-ray binaries and CVs and ABs to derive the residual thermal emission from the hot atmosphere around each galaxy. We compute the X-ray luminosity of the central supermassive black hole (SMBH). Using galaxy velocity dispersion (or stellar mass) as a proxy for SMBH mass, we derive the Eddington ratios for these low luminosity AGN. We present the X-ray luminosity and gas temperature of the hot coronae as a function of stellar mass (a proxy for dark matter halo mass) and central velocity dispersion to look for anomalously X-ray bright gaseous coronae and to determine the stellar (or halo) mass, below which galactic winds may be important. For hot coronae with X-ray cavities, we derive the "mechanical" power of SMBHs and compare these to their radiative luminosities.

  6. Cosmic star formation history and AGN evolution near and far: from AKARI to SPICA

    CERN Document Server

    Goto, Tomotsugu; Matsuhara, Hideo

    2015-01-01

    Infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe these both at low and high redshifts. The AKARI performed an all sky survey in 6 IR bands (9, 18, 65, 90, 140, and 160$\\mu$m) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can measure the total infrared luminosity ($L_{TIR}$) of individual galaxies much more precisely, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe 8$\\mu$m, 12$\\mu$m, and total infrared (TIR) luminosity functions (LFs) at 0.15$

  7. Cosmic star formation history and AGN evolution near and far: AKARI reveals both

    CERN Document Server

    Goto, Tomotsugu

    2015-01-01

    Understanding infrared (IR) luminosity is fundamental to understanding the cosmic star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese infrared satellite, AKARI, provided unique data sets to probe this both at low and high redshifts. The AKARI performed all sky survey in 6 IR bands (9, 18, 65, 90, 140, and 160$\\mu$m) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total infrared luminosity ($L_{TIR}$) of individual galaxies, and thus, the total infrared luminosity density of the local Universe. In the AKARI NEP deep field, we construct restframe 8$\\mu$m, 12$\\mu$m, and total infrared (TIR) luminosity functions (LFs) at 0.15$

  8. The z = 9-10 galaxy population in the Hubble Frontier Fields and CLASH surveys: the z = 9 luminosity function and further evidence for a smooth decline in ultraviolet luminosity density at z≥ 8

    Science.gov (United States)

    McLeod, D. J.; McLure, R. J.; Dunlop, J. S.

    2016-07-01

    We present the results of a search for z = 9-10 galaxies within the first eight pointings of the Hubble Frontier Fields (HFF) survey and 20 cluster fields from the Cluster Lensing And Supernova survey with Hubble (CLASH) survey. Combined with our previous analysis of the Hubble Ultra Deep Field, we have now completed a search for z = 9-10 galaxies over ≃ 130 arcmin2, spread across 29 Hubble Space Telescope Wide Field Camera 3/IR pointings. We confine our primary search for high-redshift candidates in this imaging to the uniformly deep, relatively low magnification regions (i.e. σ160 > 30 AB mag for HFF and σ160 > 28.8 AB mag for CLASH in 0.5-arcsec apertures). We unveil a sample of 33 galaxy candidates at zphot ≥ 8.4, five of which have primary photometric redshift solutions in the range 9.6 number density at M1500 ≃ -19.7 is log (φ ) = -4.1^{+0.2}_{-0.3}, a factor of ≃ 2 lower than at z = 9. Finally, we use our new results to revisit the issue of the decline in UV luminosity density (ρUV) at z ≥ 8. We conclude that the data continue to support a smooth decline in ρUV over the redshift interval 6 < z < 10, in agreement with simple models of early galaxy evolution driven by the growth in the underlying dark matter halo mass function.

  9. STELLAR POPULATIONS IN THE CENTRAL 0.5 pc OF THE GALAXY. I. A NEW METHOD FOR CONSTRUCTING LUMINOSITY FUNCTIONS AND SURFACE-DENSITY PROFILES

    International Nuclear Information System (INIS)

    We present new high angular resolution near-infrared spectroscopic observations of the nuclear star cluster surrounding the Milky Way's central supermassive black hole. Using the integral-field spectrograph OSIRIS on Keck II behind the laser-guide-star adaptive optics system, this spectroscopic survey enables us to separate early-type (young, 4-6 Myr) and late-type (old, >1 Gyr) stars with a completeness of 50% down to K' = 15.5 mag, which corresponds to ∼10 M ☉ for the early-type stars. This work increases the radial extent of reported OSIRIS/Keck measurements by more than a factor of three from 4'' to 14'' (0.16 to 0.56 pc), along the projected disk of young stars. For our analysis, we implement a new method of completeness correction using a combination of star-planting simulations and Bayesian inference. We assign probabilities for the spectral type of every source detected in deep imaging down to K' = 15.5 mag using information from spectra, simulations, number counts, and the distribution of stars. The inferred radial surface-density profiles, Σ(R)∝R –Γ, for the young stars and late-type giants are consistent with earlier results (Γearly = 0.93 ± 0.09, Γlate = 0.16 ± 0.07). The late-type surface-density profile is approximately flat out to the edge of the survey. While the late-type stellar luminosity function is consistent with the Galactic bulge, the completeness-corrected luminosity function of the early-type stars has significantly more young stars at faint magnitudes compared with previous surveys with similar depth. This luminosity function indicates that the corresponding mass function of the young stars is likely less top-heavy than that inferred from previous surveys.

  10. Stellar Populations in the Central 0.5 pc of the Galaxy. I. A New Method for Constructing Luminosity Functions and Surface-density Profiles

    Science.gov (United States)

    Do, T.; Lu, J. R.; Ghez, A. M.; Morris, M. R.; Yelda, S.; Martinez, G. D.; Wright, S. A.; Matthews, K.

    2013-02-01

    We present new high angular resolution near-infrared spectroscopic observations of the nuclear star cluster surrounding the Milky Way's central supermassive black hole. Using the integral-field spectrograph OSIRIS on Keck II behind the laser-guide-star adaptive optics system, this spectroscopic survey enables us to separate early-type (young, 4-6 Myr) and late-type (old, >1 Gyr) stars with a completeness of 50% down to K' = 15.5 mag, which corresponds to ~10 M ⊙ for the early-type stars. This work increases the radial extent of reported OSIRIS/Keck measurements by more than a factor of three from 4'' to 14'' (0.16 to 0.56 pc), along the projected disk of young stars. For our analysis, we implement a new method of completeness correction using a combination of star-planting simulations and Bayesian inference. We assign probabilities for the spectral type of every source detected in deep imaging down to K' = 15.5 mag using information from spectra, simulations, number counts, and the distribution of stars. The inferred radial surface-density profiles, Σ(R)vpropR -Γ, for the young stars and late-type giants are consistent with earlier results (Γearly = 0.93 ± 0.09, Γlate = 0.16 ± 0.07). The late-type surface-density profile is approximately flat out to the edge of the survey. While the late-type stellar luminosity function is consistent with the Galactic bulge, the completeness-corrected luminosity function of the early-type stars has significantly more young stars at faint magnitudes compared with previous surveys with similar depth. This luminosity function indicates that the corresponding mass function of the young stars is likely less top-heavy than that inferred from previous surveys.

  11. The roles of star formation and AGN activity of IRS sources in the HerMES fields

    Science.gov (United States)

    Feltre, A.; Hatziminaoglou, E.; Hernán-Caballero, A.; Fritz, J.; Franceschini, A.; Bock, J.; Cooray, A.; Farrah, D.; Solares, E. A. González; Ibar, E.; Isaak, K. G.; Faro, B. Lo; Marchetti, L.; Oliver, S. J.; Page, M. J.; Rigopoulou, D.; Roseboom, I. G.; Symeonidis, M.; Vaccari, M.

    2013-09-01

    In this work, we explore the impact of the presence of an active galactic nucleus (AGN) on the mid- and far-infrared (IR) properties of galaxies as well as the effects of simultaneous AGN and starburst activity in the same galaxies. To do this, we apply a multicomponent, multiband spectral synthesis technique to a sample of 250 μm selected galaxies of the Herschel Multi-tiered Extragalactic Survey (HerMES), with Infrared Spectrograph (IRS) spectra available for all galaxies. Our results confirm that the inclusion of the IRS spectra plays a crucial role in the spectral analysis of galaxies with an AGN component improving the selection of the best-fitting hot dust (torus) model. We find a correlation between the obscured star formation rate, SFRIR, derived from the IR luminosity of the starburst component, and SFRPAH, derived from the luminosity of the PAH features, LPAH, with SFRFIR taking higher values than SFRPAH. The correlation is different for AGN- and starburst-dominated objects. The ratio of LPAH to that of the starburst component, LPAH/LSB, is almost constant for AGN-dominated objects but decreases with increasing LSB for starburst-dominated objects. SFRFIR increases with the accretion luminosity, Lacc, with the increase less prominent for the very brightest, unobscured AGN-dominated sources. We find no correlation between the masses of the hot (AGN-heated) and cold (starburst-heated) dust components. We interpret this as a non-constant fraction of gas driven by the gravitational effects to the AGN while the starburst is ongoing. We also find no evidence of the AGN affecting the temperature of the cold dust component, though this conclusion is mostly based on objects with a non-dominant AGN component. We conclude that our findings do not provide evidence that the presence of AGN affects the star formation process in the host galaxy, but rather that the two phenomena occur simultaneously over a wide range of luminosities.

  12. A Direct Linkage between AGN Outflows in the Narrow-line Regions and the X-Ray Emission from the Accretion Disks

    Science.gov (United States)

    Wang, J.; Xu, D. W.; Wei, J. Y.

    2016-03-01

    The origin of outflow in the narrow-line region (NLR) of the active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [O iii]λ5007 line profile and the hard-X-ray (in a bandpass of 2-10 keV) emission from the central super-massive black hole (SMBH) in type-I AGNs. A sample of 47 local X-ray selected type-I AGNs at z\\lt 0.2 is extracted from the 2XMMi/SDSS-DR7 catalog, which was originally cross-matched by Pineau et al. The X-ray luminosities in an energy band from 2 to 10 keV of these luminous AGNs range from 1042 to {10}44 {erg} {{{s}}}-1. A joint spectral analysis is performed on their optical and X-ray spectra, in which the [O iii] line profile is modeled by a sum of several Gaussian functions to quantify its deviation from a pure Gaussian function. The statistics allow us to identify a moderate correlation with a significance level of 2.78σ: luminous AGNs with stronger [O iii] blue asymmetry tend to have steeper hard-X-ray spectra. By identifying the role of L/{L}{Edd} on the correlation at a 2-3σ significance level in both direct and indirect ways, we argue that the photon index versus the asymmetry correlation provides evidence that the AGN’s outflow commonly observed in its NLR is related to the accretion process occurring around the central SMBH, which favors the wind/radiation model as the origin of the outflow in luminous AGNs.

  13. Host Galaxy Properties of the Swift BAT Ultra Hard X-Ray Selected AGN

    Science.gov (United States)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

    2011-01-01

    We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (zBAT) sample. The BAT AGN host galaxies have intermediate optical colors (u -- r and g -- r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log Stellar Mass >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] Lambda 5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

  14. A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)

    Science.gov (United States)

    Dawson, Steve; Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Wang, JunXian; Dey, Arjun; Spinrad, Hyron; Jannuzi, Buell T.

    2007-01-01

    We present a catalog of 59 z [approx. equal to] 4:5 Ly(alpha)-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Are (LALA) narrowband imaging survey.We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of approx.76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z [approx. equal to] 4:5 Ly(alpha)- emitting galaxies in the [approx. equal to] 0.7 deg(exp 2) covered by the LALA imaging. As with the Keck LRIS sample, we find that a nonnegligible fraction of the co rest-frame equivalent widths (W(sub lambda)(sup rest)) that exceed the maximum predicted for normal stellar populations: 17%-31%(93%confidence) of the detected galaxies show (W(sub lambda)(sup rest)) 12%-27% (90% confidence) show (W(sub lambda)(sup rest)) > 240 A. We construct a luminosity function of z [approx. equal to] 4.5 Ly(alpha) emission lines for comparison to Ly(alpha) luminosity function alpha) luminosity function evolution from z [approx. equal to] 3 to z [approx. equal to] 6. This result supports the conclusion that the intergalactic me largely reionized from the local universe out to z [approx. equal to] 6.5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z approx. 3 an z approx. 6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations.

  15. Collective Properties of X-ray Binary Populations of Galaxies III. The Low-mass X-ray Binary Luminosity Function

    OpenAIRE

    Bhadkamkar, Harshal; Ghosh, Pranab

    2013-01-01

    Continuing our exploration of the collective properties of low-mass X-ray binaries (LMXBs) in the stellar fields of normal galaxies, we compute in this paper the expected X-ray luminosity function (XLF) of LMXBs, starting from the results of the previous paper in the series (Paper II). We treat separately two classes of LMXB evolution, the first being close systems whose initial orbital periods are below the bifurcation period, wherein the companion is on the main sequence when Roche-lobe con...

  16. A Study of the Luminosity and Mass Functions of the Young IC 348 Cluster using FLAMINGOS Wide-Field Near-Infrared Images

    CERN Document Server

    Münch, A; Lada, C J; Elston, R J; Alves, J F; Horrobin, M; Huard, T L; Levine, J L; Raines, S N; Román-Zunigá, C

    2003-01-01

    We present wide-field near-infrared (JHK) images of the young, 2 Myr IC 348 cluster taken with FLAMINGOS. We use these new data to construct an infrared census of sources, which is sensitive enough to detect a 10 Mjup brown dwarf seen through an extinction of Av=7mag. We examine the cluster's structure and relationship to the molecular cloud and construct the cluster's K band luminosity function. Using our model luminosity function algorithm, we derive the cluster's initial mass function throughout the stellar and substellar regimes and find that the IC 348 IMF is very similar to that found for the Trapezium Cluster with both cluster IMFs having a mode between 0.2 - 0.08 Msun. In particular we find that, similar to our results for the Trapezium, brown dwarfs constitute only 1 in 4 of the sources in the IC 348 cluster. We show that a modest secondary peak forms in the substellar IC 348 KLF, corresponding to the same mass range responsible for a similar KLF peak found in the Trapezium. We interpret this KLF pea...

  17. Impact of H_2-based star formation model on the z>=6 luminosity function and the ionizing photon budget for reionization

    CERN Document Server

    Jaacks, Jason; Nagamine, Kentaro

    2013-01-01

    We present the results of a numerical study examining the effect of H_2-based star formation (SF) model on the rest-frame UV luminosity function (UVLF) and star formation rate function (SFRF) of z>=6 galaxies, and the implications for reionization. Using cosmological hydrodynamical simulations outfitted with a new H_2-SF model, we find good agreement with our previous results (non-H_2 SF model) and observations at Muv-18, we find that the LF deviates from both our previous work and current observational estimate, producing significantly fewer low luminosity galaxies and exhibiting additional turnover at the faint end. We constrain the redshift evolution of this turnover point using a modified Schechter function that includes additional terms to quantify the turnover magnitude (Muv^t) and subsequent slope ({\\beta}). We find that Muv^t evolves from Muv^t=-17.33 (at z=8) to -15.38 (z=6), while {\\beta} becomes shallower by {\\Delta}{\\beta}=0.22 during the same epoch. This occurs in an Muv range which will be obser...

  18. Long Timescale Variability of AGN with RXTE

    International Nuclear Information System (INIS)

    In this paper we review the very large contribution made by RXTE to our understanding of Active Galaxies (AGN). We discuss the relationship between AGN and Galactic Black Hole X-ray binary systems (GBHs) and show, by comparison of their powerspectral densities (PSDs) that some AGN are the equivalent of GBHs in their 'high' state, rather than in their 'low' state as has previously been assumed. We plot the timescale at which the PSD slope steepens from -1 to -2 against the black hole mass for a sample of AGN, and for Cyg X-1 in its high and low states. We find it is not possible to fit all AGN to the same linear scaling of break timescale with black hole mass. However broad line AGN are consistent with a linear scaling of break timescale with mass from Cyg X-1 in its low state and NLS1 galaxies scale better with Cyg X-1 in its high state, although there is an exception, NGC3227. We suggest that the relationship between black hole mass and break timescale is a function of another underlying parameter which may be accretion rate or black hole spin or, probably, both. We examine X-ray spectral variability and show how simple 'flux-flux' plots can distinguish between 'two-component' and 'spectral pivoting' models. We also examine the relationship between the X-ray emission and that in other wavebands. In the case of X-ray/optical variability we show how cooler discs in AGN with larger mass black holes lead to greater proximity of the X-ray and optical emission regions and hence to more highly correlated variability. The very large amplitude of optical variability then rules out reprocessing as the origin of the optical emission. We show how the radio emission in NGC 4051 is strongly correlated with the X-ray emission, implying some contribution to the X-ray emission from a jet for which there is some evidence in radio images. We point out, however, that we have only studied in detail the X-ray variability of a handful of AGN. There is a strong requirement to extend such

  19. The Lyα luminosity function at z = 5.7 - 6.6 and the steep drop of the faint end: implications for reionization

    Science.gov (United States)

    Santos, Sérgio; Sobral, David; Matthee, Jorryt

    2016-08-01

    We present new results from the widest narrow band survey search for Lyα emitters at z = 5.7, just after reionization. We survey a total of 7 deg2 spread over the COSMOS, UDS and SA22 fields. We find over 11,000 line emitters, out of which 514 are robust Lyα candidates at z = 5.7 within a volume of 6.3 × 106 Mpc3. Our Lyα emitters span a wide range in Lyα luminosities, from faint to bright (LLyα ˜ 1042.5 - 44 erg s-1) and rest-frame equivalent widths (EW0 ˜ 25 - 1000 Å) in a single, homogeneous data-set. By combining all our fields we find that the faint end slope of the z = 5.7 Lyα luminosity function is very steep, with α =-2.3^{+0.4}_{-0.3}. We also present an updated z = 6.6 Lyα luminosity function, based on comparable volumes and obtained with the same methods, which we directly compare with that at z = 5.7. We find a significant decline of the number density of faint Lyα emitters from z = 5.7 to z = 6.6 (by 0.5 ± 0.1 dex), but no evolution at the bright end/no evolution in L★. Faint Lyα emitters at z = 6.6 show much more extended haloes than those at z = 5.7, suggesting that neutral Hydrogen plays an important role, increasing the scattering and leading to observations missing faint Lyα emission within the epoch of reionization. All together, our results suggest that we are observing patchy reionization which happens first around the brightest Lyα emitters, allowing the number densities of those sources to remain unaffected by the increase of neutral Hydrogen fraction from z ˜ 5 to z ˜ 7.

  20. AGN counts at 15um. XMM observations of the ELAIS-S1-5 sample

    CERN Document Server

    La Franca, F; Sacchi, N; Feruglio, C; Fiore, F; Gruppioni, C; Lamastra, A; Matute, I; Melini, G; Pozzi, F

    2007-01-01

    Context: The counts of galaxies and AGN in the mid infra-red (MIR) bands are important instruments for studying their cosmological evolution. However, the classic spectral line ratios techniques can become misleading when trying to properly separate AGN from starbursts or even from apparently normal galaxies. Aims: We use X-ray band observations to discriminate AGN activity in previously classified MIR-selected starburst galaxies and to derive updated AGN1 and (Compton thin) AGN2 counts at 15 um. Methods: XMM observations of the ELAIS-S1 15um sample down to flux limits ~2x10^-15 erg cm^-2 s^-1 (2-10 keV band) were used. We classified as AGN all those MIR sources with a unabsorbed 2-10 keV X-ray luminosity higher that ~10^42 erg/s. Results: We find that at least about 13(+/-6) per cent of the previously classified starburst galaxies harbor an AGN. According to these figures, we provide an updated estimate of the counts of AGN1 and (Compton thin) AGN2 at 15 um. It turns out that at least 24% of the extragalacti...