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Sample records for rate luminosity function

  1. The rate and luminosity function of long gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Pescalli, A.; Ghirlanda, G.; Salvaterra, R.; Ghisellini, G.; Vergani, S. D.; Nappo, F.; Salafia, O. S.; Melandri, A.; Covino, S.; Götz, D.

    2016-03-01

    We derive, adopting a direct method, the luminosity function and the formation rate of long Gamma Ray Bursts through a complete, flux-limited, sample of Swift bursts which has a high level of completeness in redshift z (~82%). We parametrise the redshift evolution of the GRB luminosity as L = L0(1 + z)k and we derive k = 2.5, consistently with recent estimates. The de-evolved luminosity function φ(L0) of GRBs can be represented by a broken power law with slopes a = -1.32 ± 0.21 and b = -1.84 ± 0.24 below and above, respectively, a break luminosity L0,b = 1051.45±0.15 erg/s. Under the hypothesis of luminosity evolution we find that the GRB formation rate increases with redshift up to z ~ 2, where it peaks, and then decreases in agreement with the shape of the cosmic star formation rate. We test the direct method through numerical simulations and we show that if it is applied to incomplete (both in redshift and/or flux) GRB samples it can misleadingly result in an excess of the GRB formation rate at low redshifts.

  2. The Protostellar Luminosity Function

    NASA Astrophysics Data System (ADS)

    Offner, Stella S. R.; McKee, Christopher F.

    2011-07-01

    The protostellar luminosity function (PLF) is the present-day luminosity function of the protostars in a region of star formation. It is determined using the protostellar mass function in combination with a stellar evolutionary model that provides the luminosity as a function of instantaneous and final stellar mass. In 2010, McKee & Offner considered three main accretion models: the isothermal sphere (IS) model, the turbulent core (TC) model, and an approximation of the competitive accretion (CA) model. We also consider the effect of an accretion rate that tapers off linearly in time and an accelerating star formation rate. For each model, we characterize the luminosity distribution using the mean, median, maximum, ratio of the median to the mean, standard deviation of the logarithm of the luminosity, and the fraction of very low luminosity objects. We compare the models with bolometric luminosities observed in local star-forming regions and find that models with an approximately constant accretion time, such as the TC and CA models, appear to agree better with observation than those with a constant accretion rate, such as the IS model. We show that observations of the mean protostellar luminosity in these nearby regions of low-mass star formation suggest a mean star formation time of 0.3 ± 0.1 Myr. Such a timescale, together with some accretion that occurs non-radiatively and some that occurs in high-accretion, episodic bursts, resolves the classical "luminosity problem" in low-mass star formation, in which observed protostellar luminosities are significantly less than predicted. An accelerating star formation rate is one possible way of reconciling the observed star formation time and mean luminosity. Future observations will place tighter constraints on the observed luminosities, star formation time, and episodic accretion, enabling better discrimination between star formation models and clarifying the influence of variable accretion on the PLF.

  3. THE PROTOSTELLAR LUMINOSITY FUNCTION

    SciTech Connect

    Offner, Stella S. R.; McKee, Christopher F. E-mail: cmckee@astro.berkeley.edu

    2011-07-20

    The protostellar luminosity function (PLF) is the present-day luminosity function of the protostars in a region of star formation. It is determined using the protostellar mass function in combination with a stellar evolutionary model that provides the luminosity as a function of instantaneous and final stellar mass. In 2010, McKee and Offner considered three main accretion models: the isothermal sphere (IS) model, the turbulent core (TC) model, and an approximation of the competitive accretion (CA) model. We also consider the effect of an accretion rate that tapers off linearly in time and an accelerating star formation rate. For each model, we characterize the luminosity distribution using the mean, median, maximum, ratio of the median to the mean, standard deviation of the logarithm of the luminosity, and the fraction of very low luminosity objects. We compare the models with bolometric luminosities observed in local star-forming regions and find that models with an approximately constant accretion time, such as the TC and CA models, appear to agree better with observation than those with a constant accretion rate, such as the IS model. We show that observations of the mean protostellar luminosity in these nearby regions of low-mass star formation suggest a mean star formation time of 0.3 {+-} 0.1 Myr. Such a timescale, together with some accretion that occurs non-radiatively and some that occurs in high-accretion, episodic bursts, resolves the classical 'luminosity problem' in low-mass star formation, in which observed protostellar luminosities are significantly less than predicted. An accelerating star formation rate is one possible way of reconciling the observed star formation time and mean luminosity. Future observations will place tighter constraints on the observed luminosities, star formation time, and episodic accretion, enabling better discrimination between star formation models and clarifying the influence of variable accretion on the PLF.

  4. Extra-galactic high-energy transients: event rate density and luminosity function

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-08-01

    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 a relativistic jet. In this paper, we apply a unified method to systematically study the reshift-dependent event rate densities and luminosity functions of these extra-galactic high-energy transients. We consider star formation history as the tracer of the redshift distribution for long GRBs and SBOs. For short GRBs, we consider the compact star merger model to introduce several possible merger delay time distribution models. For TDEs, we consider the mass distribution of supermassive black holes as a function of redshift. We derive some empirical formulae for the redshift-dependent event rate density for different types of transients. Based on the observed events, we derive the local specific event rate density, ρ0,L ∝ dρ0/dL for each type of transient, which represents its luminosity function. All the transients are consistent with having a single power law luminosity function, except the high luminosity long GRBs (HL-lGRBs), whose luminosity function can be well described by a broken power law. The total event rate density for a particular transient depends on the luminosity threshold, and we obtain the following values in units of Gpc-3 yr-1: 2.82^{+0.41}_{-0.36} for HL-lGRBs above 4×1049 erg s-1 218^{+130}_{-86} for low luminosity long GRBs above 6×1046 erg s-1 3.18^{+0.88}_{-0.70}, 2.87^{+0.80}_{-0.64}, and 6.25^{+1.73}_{-1.38} above 5×1049 erg s-1 for short GRBs with three different merger delay models (Gaussian, log-normal, and power law); 2.0^{+2.6}_{-1.3}×104 above 9×1043 erg s-1 for SBOs, 3.0^{+1.0}_{-0.8}×105 for normal TDEs above 1042 erg s-1 and 6.2^{+8.2}_{-4.0} above 3×1047 erg s-1for TDE jets as discovered by Swift. Intriguingly, the global specific event rate densities

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

    NASA Astrophysics Data System (ADS)

    Howell, E. J.; Coward, D. M.; Stratta, G.; Gendre, B.; Zhou, H.

    2014-10-01

    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 Vmax 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 Swift, we use recent results of Lien et al. (2014) 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 (without beaming corrections) of [0.7 < ρ0 < 0.8] Gpc-3 yr-1. Within this range, assuming a broken power-law LF, we find best estimates for the low- and high-energy indices of -0.95 ± 0.09 and -2.59 ± 0.93, respectively, separated by a break luminosity 0.80 ± 0.43 × 1052 erg s-1.

  6. Extragalactic High-energy Transients: Event Rate Densities and Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-10-01

    Several types of extragalactic 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 (GLFs; 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 GLF. Long GRBs (LGRBs) have a large enough sample to reveal features in the GLF, which is best charaterized as a triple power law (PL). All the other transients are consistent with having a single-power-law (SPL) LF. The total event rate density depends on the minimum luminosity, and we obtain the following values in units of Gpc-3 yr-1: {0.8}-0.1+0.1 for high-luminosity LGRBs above 1050 erg s-1 {164}-65+98 for low-luminosity LGRBs above 5 × 1046 erg s-1 {1.3}-0.3+0.4, {1.2}-0.3+0.4, and {3.3}-0.8+1.0 above 1050 erg s-1 for short GRBs with three different merger delay models (Gaussian, lognormal, and PL); {1.9}-1.2+2.4× {10}4 above 1044 erg s-1 for SBOs, {4.8}-2.1+3.2× {10}2 for normal TDEs above 1044 erg s-1 and {0.03}-0.02+0.04 above 1048 erg s-1 for TDE jets as discovered by Swift. Intriguingly, the GLFs of different kinds of transients, which cover over 12 orders of magnitude, are consistent with an SPL with an index of -1.6.

  7. The H alpha Luminosity Function and Star Formation Rate at Z approximately 0.2

    NASA Astrophysics Data System (ADS)

    Tresse, Laurence; Maddox, Steve J.

    1998-03-01

    We have measured the Hα + [N II] fluxes of the I-selected Canada-France Redshift Survey (CFRS) galaxies lying at a redshift z below 0.3 and hence derived the Hα luminosity function. The magnitude limits of the CFRS mean that only the galaxies with MB >~ -21 mag were observed at these redshifts. We obtained a total Hα luminosity density of at least 1039.44+/-0.04 ergs s-1 Mpc-3 at a mean z = 0.2 for galaxies with rest-frame EW(Hα + [N II]) >~ 10 Å. This is twice the value found in the local universe by Gallego et al. Our Hα star formation rate, derived from Madau, is higher than the UV observations at the same z, implying a UV dust extinction of ~1 mag. We found a strong correlation between the Hα luminosity and the absolute magnitude in the B band: M(BAB) = 46.7 - 1.6 log L(Hα). This work will serve as a basis of future studies of Hα luminosity distributions measured from optically selected spectroscopic surveys of the distant universe, and it will provide a better understanding of the physical processes responsible for the observed galaxy evolution.

  8. The rate, luminosity function and time delay of non-Collapsar short GRBs

    NASA Astrophysics Data System (ADS)

    Wanderman, David; Piran, Tsvi

    2015-04-01

    We estimate the rate and the luminosity function of short (hard) Gamma-Ray Bursts (sGRBs) that are non-Collapsars, using the peak fluxes and redshifts of BATSE, Swift and Fermi GRBs. Following Bromberg et al., we select a sub-sample of Swift bursts which are most likely non-Collapsars. We find that these sGRBs are delayed relative to the global star formation rate (SFR) with a typical delay time of a 3-4 Gyr (depending on the SFR model). However, if two or three sGRB at high redshifts have been missed because of selection effects, a distribution of delay times of ∝ 1/t would be also compatible. The current event rate of these non-Collapsar sGRBs with Liso > 5 × 1049 erg s-1 is 4.1_{-1.9}^{+2.3} Gpc^{-3} yr^{-1}. The rate was significantly larger around z ˜ 1 and it declines since that time. The luminosity function we find is a broken power law with a break at 2.0_{-0.4}^{+1.4} × 10^{52} erg s^{-1} and power-law indices 0.95_{-0.1 2}^{+0.12} and 2.0_{-0.8}^{+1.0}. When considering the whole Swift sGRB sample we find that it is composed of two populations: one group (≈60-80 per cent of Swift sGRBs) with the above rate and time delay and a second group (≈20-40 per cent of Swift sGRBs) of potential `impostors' that follow the SFR with no delay. These two populations are in very good agreement with the division of sGRBs to non-Collapsars and Collapsars suggested recently by Bromberg et al. If non-Collapsar sGRBs arise from neutron star merger this rate suggest a detection rate of 3-100 yr-1 by a future gravitational wave detectors (e.g. Advanced Ligo/Virgo with detection horizon on 300 Mpc), and a co-detection with Fermi (Swift ) rate of 0.1-1 yr-1 (0.02-0.14 yr-1). We estimate that about 4 × 10^5 (f_b^{-1}/30) mergers took place in the Milky Way. If 0.025M⊙ were ejected in each event this would have been sufficient to produce all the heavy r-process material in the Galaxy.

  9. An empirical model for the galaxy luminosity and star formation rate function at high redshift

    NASA Astrophysics Data System (ADS)

    Mashian, Natalie; Oesch, Pascal A.; Loeb, Abraham

    2016-01-01

    Using the most recent measurements of the ultraviolet (UV) luminosity functions (LFs) and dust estimates of early galaxies, we derive updated dust-corrected star formation rate functions (SFRFs) at z ˜ 4-8, which we model to predict the evolution to higher redshifts, z > 8. We employ abundance matching techniques to calibrate a relation between galaxy star formation rate (SFR) and host halo mass Mh by mapping the shape of the observed SFRFs at z ˜ 4-8 to that of the halo mass function. The resulting scaling law remains roughly constant over this redshift range. We apply the average SFR-Mh relation to reproduce the observed SFR functions at 4 ≲ z ≲ 8 and also derive the expected UV LFs at higher redshifts. At z ˜ 9 and z ˜ 10 these model LFs are in excellent agreement with current observed estimates. Our predicted number densities and UV LFs at z > 10 indicate that James Webb Space Telescope will be able to detect galaxies out to z ˜ 15 with an extensive treasury sized program. We also derive the redshift evolution of the star formation rate density (SFRD) and associated reionization history by galaxies. Models which integrate down to the current HUDF12/XDF detection limit (MUV ˜ -17.7 mag) result in a SFRD that declines as (1 + z)-10.4 ± 0.3 at high redshift and fail to reproduce the observed cosmic microwave background electron scattering optical depth, τ ≃ 0.066, to within 1σ. On the other hand, we find that the inclusion of galaxies with SFRs well below the current detection limit (MUV < -5.7 mag) leads to a fully reionized universe by z ˜ 6.5 and an optical depth of τ ≃ 0.054, consistent with the recently derived Planck value at the 1σ level.

  10. THE COSMIC RATE, LUMINOSITY FUNCTION, AND INTRINSIC CORRELATIONS OF LONG GAMMA-RAY BURSTS

    SciTech Connect

    Butler, Nathaniel R.; Bloom, Joshua S.; Poznanski, Dovi

    2010-03-01

    We calculate durations and spectral parameters for 207 Swift bursts detected by the Burst Alert Telescope from 2007 April to 2009 August, including 67 events with measured redshifts. This is the first supplement to our catalog of 425 Swift gamma-ray bursts (GRBs; 147 with redshifts) starting from GRB 041220. This complete and extensive data set, analyzed with a unified methodology, allows us to conduct an accurate census of intrinsic GRB energetics, hardnesses, durations, and redshifts. The GRB world model we derive reproduces well the observables from both Swift and pre-Swift satellites. Comparing to the cosmic star formation rate, we estimate that only about 0.1% of massive stars explode as bright GRBs. There is strong evidence for evolution in the Swift population at intermediate and high-z, and we can rule out (at the 5sigma level) that this is due to evolution in the luminosity function of GRBs. Instead, the Swift sample suggests a modest propensity for low metallicity, evidenced by an increase in the rate density with redshift. Treating the multivariate data and selection effects rigorously, we find a real, intrinsic correlation between E{sub iso} and E{sub pk} (and possibly also T{sub r45,z}); however, the correlation is not a narrow log-log relation and its observed appearance is strongly detector-dependent. We also estimate the high-z rate (3%-9% of GRBs at z beyond 5) and discuss the extent of a large missing population of low-E{sub pk,obs} X-ray flashes as well as a potentially large missing population of short-duration GRBs that will be probed by EXIST.

  11. The white dwarf luminosity function

    NASA Astrophysics Data System (ADS)

    García-Berro, Enrique; Oswalt, Terry D.

    2016-06-01

    White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for ∼ 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 relevant ingredients are needed to compare theory and observations. In this review we summarize the recent attempts to empirically determine the white dwarf luminosity function for the different Galactic populations. We also discuss the biases that may affect its interpretation. Finally, we elaborate on the theoretical ingredients needed to model the white dwarf luminosity function, paying special attention to the remaining uncertainties, and we comment on some applications of the white dwarf cooling theory. Astrophysical problems for which white dwarf stars may provide useful leverage in the near future are also discussed.

  12. The Local [CII] Emission Line Luminosity Function

    NASA Astrophysics Data System (ADS)

    Hemmati, Shoubaneh

    2017-01-01

    I present, for the first time, the local [CII]158 $\\mu$m emission line luminosity function measured using a sample of more than 500 galaxies from the RBGS. [CII] luminosities are measured from the Herschel PACS observations of the LIRGs in the GOALS survey and estimated for the rest of the sample based on the far-IR luminosity and color. The sample covers 91.3% of the sky and is complete at $S_{60\\mu m} > 5.24 Jy$. We calculated the completeness as a function of [CII] line luminosity and distance, based on the far-IR color and flux densities. The [CII] luminosity function is constrained in the range $\\sim 10^{7-9} \\ L_{\\odot}$ from both the 1/Vmax and the STY maximum likelihood methods. The shape of our derived [CII] emission line luminosity function agrees well with the IR luminosity function. For the CO(1-0) and [CII] luminosity functions to agree, we propose a varying ratio of [CII]/CO(1-0) as a function of CO luminosity, with larger ratios for fainter CO luminosities. Limited [CII] high redshift observations as well as estimates based on the IR and UV luminosity functions, are suggestive of an evolution in the [CII] luminosity function similar to the evolution trend of the cosmic star formation rate density. ALMA with full capability will be able to confirm this prediction.

  13. STAR FORMATION IN THE BULLET CLUSTER. I. THE INFRARED LUMINOSITY FUNCTION AND STAR FORMATION RATE ,

    SciTech Connect

    Sun Mi Chung; Gonzalez, Anthony H.; Clowe, Douglas; Markevitch, Maxim; Zaritsky, Dennis

    2010-12-20

    The Bullet Cluster is a massive galaxy cluster at z = 0.297 undergoing a major supersonic (Mach 3) merger event. Using data from Spitzer MIPS and the Infrared Array Camera, optical imaging, and optical spectroscopy, we present the global star formation rate (SFR) of this unique cluster. Using a 90% spectroscopically complete sample of 37 star-forming MIPS confirmed cluster members out to R < 1.7 Mpc, and the Rieke et al. relation to convert from 24 {mu}m flux to SFR, we calculate an integrated obscured SFR of 267 M{sub sun} yr{sup -1} and a specific SFR of 28 M{sub sun} yr{sup -1} per 10{sup 14} M{sub sun}. The cluster mass normalized integrated SFR of the Bullet Cluster is among the highest in a sample of eight other clusters and cluster mergers from the literature. Five LIRGs and one ULIRG contribute 30% and 40% of the total SFR of the cluster, respectively. To investigate the origin of the elevated specific SFR, we compare the infrared luminosity function (IR LF) of the Bullet Cluster to those of Coma (evolved to z = 0.297) and CL1358+62. The Bullet Cluster IR LF exhibits an excess of sources compared to the IR LFs of the other massive clusters. A Schechter function fit of the Bullet Cluster IR LF yields L* = 44.68 {+-} 0.11 erg s{sup -1}, which is {approx}0.25 and 0.35 dex brighter than L* of evolved Coma and CL1358+62, respectively. The elevated IR LF of the Bullet Cluster relative to other clusters can be explained if we attribute the 'excess' star-forming IR galaxies to a population associated with the infalling group that has not yet been transformed into quiescent galaxies. In this case, the timescale required for quenching star formation in the cluster environment must be longer than the timescale since the group's accretion-a few hundred million years. We suggest that 'strangulation' is likely to be an important process in the evolution of star formation in clusters.

  14. Binary black hole merger rates inferred from luminosity function of ultra-luminous X-ray sources

    NASA Astrophysics Data System (ADS)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.; Isobe, Naoki

    2016-10-01

    The Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) has detected direct signals of gravitational waves (GWs) from GW150914. The event was a merger of binary black holes whose masses are 36^{+5}_{-4} M_{{⊙}} and 29^{+4}_{-4} M_{{⊙}}. Such binary systems are expected to be directly evolved from stellar binary systems or formed by dynamical interactions of black holes in dense stellar environments. Here we derive the binary black hole merger rate based on the nearby ultra-luminous X-ray source (ULX) luminosity function (LF) under the assumption that binary black holes evolve through X-ray emitting phases. We obtain the binary black hole merger rate as 5.8(tULX/0.1 Myr)- 1λ- 0.6exp ( - 0.30λ) Gpc- 3 yr- 1, where tULX is the typical duration of the ULX phase and λ is the Eddington ratio in luminosity. This is coincident with the event rate inferred from the detection of GW150914 as well as the predictions based on binary population synthesis models. Although we are currently unable to constrain the Eddington ratio of ULXs in luminosity due to the uncertainties of our models and measured binary black hole merger event rates, further X-ray and GW data will allow us to narrow down the range of the Eddington ratios of ULXs. We also find the cumulative merger rate for the mass range of 5 M⊙ ≤ MBH ≤ 100 M⊙ inferred from the ULX LF is consistent with that estimated by the aLIGO collaboration considering various astrophysical conditions such as the mass function of black holes.

  15. The faint quasar luminosity function

    NASA Technical Reports Server (NTRS)

    Kron, Richard G.; Bershady, Matthew A.; Munn, Jeffrey A.; Smetanka, John J.; Majewski, Steven; Koo, David C.

    1991-01-01

    Preliminary results of an expanded program to determine the faint-quasar luminosity function are described. Quasars have been selected in four fields totaling 1.2 sq deg from four-band photometry. Out of a total of 130 quasars with good spectroscopy, 37 have J greater than 21.5 and 46 have F greater than 21.0. The spectroscopic sample is representative of all of the color-selected candidates. An estimate of the luminosity function as a function of redshift is derived.

  16. Multiwavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan; Oegerle, William R. (Technical Monitor)

    2002-01-01

    I have developed a technique for measuring multi-variate luminosity functions of galaxies. Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and absorption and re-emission of dust within evolving galaxy populations. By using principle component analysis to reduce the dimensionality of the problem, I optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, I derive the multiwavelength luminosity function for the galaxies in the released SDSS catalog, and show that the results are consistent with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by the SIRTF and GALEX missions.

  17. Does the evolution of the radio luminosity function of star-forming galaxies match that of the star formation rate function?

    NASA Astrophysics Data System (ADS)

    Bonato, Matteo; Negrello, Mattia; Mancuso, Claudia; De Zotti, Gianfranco; Ciliegi, Paolo; Cai, Zhen-Yi; Lapi, Andrea; Massardi, Marcella; Bonaldi, Anna; Sajina, Anna; Smolc̆ić, Vernesa; Schinnerer, Eva

    2017-08-01

    The assessment of the relationship between radio continuum luminosity and star formation rate (SFR) is of crucial importance to make reliable predictions for the forthcoming ultra-deep radio surveys and to allow a full exploitation of their results to measure the cosmic star formation history. We have addressed this issue by matching recent accurate determinations of the SFR function up to high redshifts with literature estimates of the 1.4 GHz luminosity functions of star-forming galaxies (SFGs). This was done considering two options, proposed in the literature, for the relationship between the synchrotron emission (Lsynch), that dominates at 1.4 GHz, and the SFR: a linear relation with a decline of the Lsynch/SFR ratio at low luminosities or a mildly non-linear relation at all luminosities. In both cases, we get good agreement with the observed radio luminosity functions but, in the non-linear case, the deviation from linearity must be small. The luminosity function data are consistent with a moderate increase of the Lsynch/SFR ratio with increasing redshift, indicated by other data sets, although a constant ratio cannot be ruled out. A stronger indication of such increase is provided by recent deep 1.4-GHz counts, down to μJy levels. This is in contradiction with models predicting a decrease of that ratio due to inverse Compton cooling of relativistic electrons at high redshifts. Synchrotron losses appear to dominate up to z ≃ 5. We have also updated the Massardi et al. evolutionary model for radio loud AGNs.

  18. The luminosity function of quasars

    NASA Technical Reports Server (NTRS)

    Pei, Yichuan C.

    1995-01-01

    We propose a new evolutionary model for the optical luminosity function of quasars. Our analytical model is derived from fits to the empirical luminosity function estimated by Hartwick and Schade and Warren, Hewett, and Osmer on the basis of more than 1200 quasars over the range of redshifts 0 approximately less than z approximately less than 4.5. We find that the evolution of quasars over this entire redshift range can be well fitted by a Gaussian distribution, while the shape of the luminosity function can be well fitted by either a double power law or an exponential L(exp 1/4) law. The predicted number counts of quasars, as a function of either apparent magnitude or redshift, are fully consistent with the observed ones. Our model indicates that the evolution of quasars reaches its maximum at z approximately = 2.8 and declines at higher redshifts. An extrapolation of the evolution to z approximately greater than 4.5 implies that quasars may have started their cosmic fireworks at z(sub f) approximately = 5.2-5.5. Forthcoming surveys of quasars at these redshifts will be critical to constrain the epoch of quasar formation. All the results we derived are based on observed quasars and are therefore subject to the bias of obscuration by dust in damped Ly alpha systems. Future surveys of these absorption systems at z approximately greater than 3 will also be important if the formation epoch of quasars is to be known unambiguously.

  19. The luminosity function of quasars

    NASA Technical Reports Server (NTRS)

    Pei, Yichuan C.

    1995-01-01

    We propose a new evolutionary model for the optical luminosity function of quasars. Our analytical model is derived from fits to the empirical luminosity function estimated by Hartwick and Schade and Warren, Hewett, and Osmer on the basis of more than 1200 quasars over the range of redshifts 0 approximately less than z approximately less than 4.5. We find that the evolution of quasars over this entire redshift range can be well fitted by a Gaussian distribution, while the shape of the luminosity function can be well fitted by either a double power law or an exponential L(exp 1/4) law. The predicted number counts of quasars, as a function of either apparent magnitude or redshift, are fully consistent with the observed ones. Our model indicates that the evolution of quasars reaches its maximum at z approximately = 2.8 and declines at higher redshifts. An extrapolation of the evolution to z approximately greater than 4.5 implies that quasars may have started their cosmic fireworks at z(sub f) approximately = 5.2-5.5. Forthcoming surveys of quasars at these redshifts will be critical to constrain the epoch of quasar formation. All the results we derived are based on observed quasars and are therefore subject to the bias of obscuration by dust in damped Ly alpha systems. Future surveys of these absorption systems at z approximately greater than 3 will also be important if the formation epoch of quasars is to be known unambiguously.

  20. Luminosity Function Statistics Applied in GRB Samples

    NASA Astrophysics Data System (ADS)

    Lemos, Luis Juracy Rangel; Bianco, Carlo L.; Ruffini, Remo

    The luminosity function (LF) statistics applied in data of GRBs detected by 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 produced, by LF statistics, the GRB predicted distributions of: peak ux N(Fpk), redshift N(z) and peak luminosity N(Lpk). We also used different GRB rates. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with more then 250 GRBs with known redshifts. We estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy.

  1. Galaxy And Mass Assembly: evolution of the Hα luminosity function and star formation rate density up to z < 0.35

    NASA Astrophysics Data System (ADS)

    Gunawardhana, M. L. P.; Hopkins, A. M.; Bland-Hawthorn, J.; Brough, S.; Sharp, R.; Loveday, J.; Taylor, E.; Jones, D. H.; Lara-López, M. A.; Bauer, A. E.; Colless, M.; Owers, M.; Baldry, I. K.; López-Sánchez, A. R.; Foster, C.; Bamford, S.; Brown, M. J. I.; Driver, S. P.; Drinkwater, M. J.; Liske, J.; Meyer, M.; Norberg, P.; Robotham, A. S. G.; Ching, J. H. Y.; Cluver, M. E.; Croom, S.; Kelvin, L.; Prescott, M.; Steele, O.; Thomas, D.; Wang, L.

    2013-08-01

    Measurements of the low-z Hα luminosity function, Φ, have a large dispersion in the local number density of sources (˜0.5-1 Mpc-3 dex-1), and correspondingly in the star formation rate density (SFRD). The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, different methods of correcting for dust obscuration and active galactic nucleus contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 < SFRHα (M⊙ yr- 1) < 100 with which to robustly measure the evolution of the SFRD in the low-z Universe. The large number of high-SFR galaxies present in our sample allow an improved measurement of the bright end of the luminosity function, indicating that the decrease in Φ at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the far-infrared and radio. For GAMA and SDSS, we find the r-band apparent magnitude limit, combined with the subsequent requirement for Hα detection leads to an incompleteness due to missing bright Hα sources with faint r-band magnitudes.

  2. Ultra-faint ultraviolet galaxies at z ∼ 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    SciTech Connect

    Alavi, Anahita; Siana, Brian; Freeman, William R.; Dominguez, Alberto; Richard, Johan; Stark, Daniel P.; Robertson, Brant; Scarlata, Claudia; Teplitz, Harry I.; Rafelski, Marc; Kewley, Lisa

    2014-01-10

    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 {sub 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 {sub 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 {sub ☉}) compared to their brighter counterparts (Z {sub ☉}), 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{sub −0.60}{sup +0.68}×10{sup 26} erg s{sup –1} Hz{sup –1} Mpc{sup –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

  3. Construction of luminosity function for galaxy clusters

    NASA Astrophysics Data System (ADS)

    Godłowski, Włodzimierz; Popiela, Joanna; Bajan, Katarzyna; Biernacka, Monika; Flin, Piotr; Panko, Elena

    2015-02-01

    The luminosity function is an important quantity for analysis of large scale structure statistics, interpretation of galaxy counts (Lin & Kirshner 1996). We investigate the luminosity function of galaxy clusters. This is performed by counting the brightness of galaxies belonging to clusters in PF Catalogue. The obtained luminosity function is significantly different than that obtained both for optical and radiogalaxies (Machalski & Godowski 2000). The implications of this result for theories of galaxy formation are discussed as well.

  4. Evolution of the luminosity function of quasar accretion disks

    NASA Technical Reports Server (NTRS)

    Caditz, David M.; Petrosian, Vahe; Wandel, Amri

    1991-01-01

    Using an accretion-disk model, accretion disk luminosities are calculated for a grid of black hole masses and accretion rates. It is shown that, as the black-hole mass increases with time, the monochromatic luminosity at a given frequency first increases and then decreases rapidly as this frequency is crossed by the Wien cutoff. The upper limit on the monochromatic luminosity, which is characteristic for a given epoch, constrains the evolution of quasar luminosities and determines the evolultion of the quasar luminosity function.

  5. The Luminosity Function and Star Formation Rate Between Redshifts of 0.07 and 1.47 for Narrow-band Emitters in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malkan, M.; Kashikawa, N.; Shimasaku, K.; Doi, M.; Nagao, T.; Iye, M.; Kodama, T.; Morokuma, T.; Motohara, K.

    2006-06-01

    Subaru Deep Field line-emitting galaxies in four narrow-band filters at low and intermediate redshifts are presented. Broad-band colors, follow-up optical spectroscopy, and multiple narrow-band filters are used to distinguish Hα, [OII], and [OIII] emitters between redshifts of 0.07 and 1.47 to construct their averaged rest-frame optical-to-UV SED and luminosity functions. These luminosity functions are derived down to faint magnitudes, which allows for a more accurate determination of the faint end slope. With a large (N 200-900) sample for each redshift interval, a Schechter profile is fitted to each luminosity function. Prior to dust extinction corrections, the [OIII] and [OII] luminosity functions reported in this paper agree reasonably well with those of Hippelein et al (2003). The z=0.066-0.092 Hα LF agrees with those of Jones & Bland-Hawthorn (2001), but for z=0.24 and 0.40, their number density is higher by a factor of two or more. The z=0.08 Hα LF, which reaches two orders of magnitude fainter than Gallego et al. (1995), is steeper by 25%. This indicates that there are more low luminosity star-forming galaxies for z<0.1 than predicted. The faint end slope α and φ* show a strong evolution with redshift while L* show little evolution. The evolution in α indicates that low-luminosity galaxies have a stronger evolution compared to brighter ones. Integrated star formation rate densities are derived via Hα for 0.07rate density, as a function of redshift, is seen for 0.4rate density is more or less the same. The latter is consistent with previous UV and [OII] measurements. Below z<0.4, the SFR densities are consistent with several measurements, but other measurements disagree by a factor of two higher. This discrepancy can be explained by cosmic variance.

  6. A Flexible Method of Estimating Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Kelly, Brandon C.; Fan, Xiaohui; Vestergaard, Marianne

    2008-08-01

    We describe a Bayesian approach to estimating luminosity functions. We derive the likelihood function and posterior probability distribution for the luminosity function, given the observed data, and we compare the Bayesian approach with maximum likelihood by simulating sources from a Schechter function. For our simulations confidence intervals derived from bootstrapping the maximum likelihood estimate can be too narrow, while confidence intervals derived from the Bayesian approach are valid. We develop our statistical approach for a flexible model where the luminosity function is modeled as a mixture of Gaussian functions. Statistical inference is performed using Markov chain Monte Carlo (MCMC) methods, and we describe a Metropolis-Hastings algorithm to perform the MCMC. The MCMC simulates random draws from the probability distribution of the luminosity function parameters, given the data, and we use a simulated data set to show how these random draws may be used to estimate the probability distribution for the luminosity function. In addition, we show how the MCMC output may be used to estimate the probability distribution of any quantities derived from the luminosity function, such as the peak in the space density of quasars. The Bayesian method we develop has the advantage that it is able to place accurate constraints on the luminosity function even beyond the survey detection limits, and that it provides a natural way of estimating the probability distribution of any quantities derived from the luminosity function, including those that rely on information beyond the survey detection limits.

  7. Evolution of the luminosity function of extragalactic objects

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1985-01-01

    A nonparametric procedure for determination of the evolution of the luminosity function of extragalactic objects and use of this for prediction of expected redshift and luminosity distribution of objects is described. The relation between this statistical evolution of the population and their physical evolution, such as the variation with cosmological epoch of their luminosity and formation rate is presented. This procedure when applied to a sample of optically selected quasars with redshifts less than two shows that the luminosity function evolves more strongly for higher luminosities, indicating a larger quasar activity at earlier epochs and a more rapid evolution of the objects during their higher luminosity phases. It is also shown that absence of many quasars at redshifts greater than three implies slowing down of this evolution in the conventional cosmological models, perhaps indicating that this is near the epoch of the birth of the quasar (and galaxies).

  8. Ultra-faint Ultraviolet Galaxies at z ~ 2 behind the Lensing Cluster A1689: The Luminosity Function, Dust Extinction, and Star Formation Rate Density

    NASA Astrophysics Data System (ADS)

    Alavi, Anahita; Siana, Brian; Richard, Johan; Stark, Daniel P.; Scarlata, Claudia; Teplitz, Harry I.; Freeman, William R.; Dominguez, Alberto; Rafelski, Marc; Robertson, Brant; Kewley, Lisa

    2014-01-01

    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 langE(B - V)rang = 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^{+0.68}_{-0.60} \\times 10^{26} 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 initial

  9. Correlation function of the luminosity distances

    NASA Astrophysics Data System (ADS)

    Biern, Sang Gyu; Yoo, Jaiyul

    2017-09-01

    We present the correlation function of the luminosity distances in a flat ΛCDM universe. Decomposing the luminosity distance fluctuation into the velocity, the gravitational potential, and the lensing contributions in linear perturbation theory, we study their individual contributions to the correlation function. The lensing contribution is important at large redshift (z gtrsim 0.5) but only for small angular separation (θ lesssim 3°), while the velocity contribution dominates over the other contributions at low redshift or at larger separation. However, the gravitational potential contribution is always subdominant at all scale, if the correct gauge-invariant expression is used. The correlation function of the luminosity distances depends significantly on the matter content, especially for the lensing contribution, thus providing a novel tool of estimating cosmological parameters.

  10. Radio luminosity function of brightest cluster galaxies

    NASA Astrophysics Data System (ADS)

    Yuan, Z. S.; Han, J. L.; Wen, Z. L.

    2016-08-01

    By cross-matching the currently largest optical catalogue of galaxy clusters and the NVSS radio survey data base, we obtain a large complete sample of brightest cluster galaxies (BCGs) in the redshift range of 0.05 < z ≤ 0.45, which have radio emission and redshift information. We confirm that more powerful radio BCGs tend to be these optically very bright galaxies located in more relaxed clusters. We derived the radio luminosity functions of the largest sample of radio BCGs, and find that the functions depend on the optical luminosity of BCGs and the dynamic state of galaxy clusters. However, the radio luminosity function does not show significant evolution with redshift.

  11. Multi-wavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, J. P.; Miller, N. A.

    2002-01-01

    Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and absorption and re-emission of dust within evolving galaxy populations. By using principal component analysis to reduce the dimensionality of the problem, we optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, we derive the multi-wavelength luminosity function for the galaxies in the released SDSS catalog, and compare the results with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by 2MASS, and the SIRTF and GALEX missions.

  12. Multi-Wavelength Luminosity Functions of Galaxies

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan P.

    2002-01-01

    Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and ab- sorption and re-emission of dust within evolving galaxy populations. By using principal component analysis to reduce the dimensionality of the problem, I optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, I derive the multi-wavelength luminosity function for the galaxies in the released SDSS catalog, and compare the results with those obtained by traditional methods. This technique will be applicable to catalogs of galaxies from datasets obtained by 2MASS, and the SIRTF and GALEX missions.

  13. X-Ray Counterpart of Gravitational Waves Due to Binary Neutron Star Mergers: Light Curves, Luminosity Function, and Event Rate Density

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Zhang, Bing; Gao, He

    2017-01-01

    Zhang proposed a type of GRB-less X-ray transient associated with double neutron star (NS–NS) mergers under the conjecture of a rapidly spinning magnetar merger product with the line of sight off the short gamma-ray burst (GRB) jet. We investigate possible light curves of these transients by considering different observers’ viewing angles. We perform Monte Carlo simulations to calculate the peak luminosity function (LF) and event rate density of these X-ray transients. By considering that a fraction of massive neutron stars may be supra-massive and later collapse into black holes after spinning down, we investigate how the predicted LF depends on the equation of state (EoS) of the central object and the geometry of the system. In general, the LF can be fit by two log-normal distributions peaking around {10}46.4 and {10}49.6 {erg} {{{s}}}-1, corresponding to the trapped and free zones, respectively. For the majority of the EoS models, the current non-detection is consistent with having a free zone solid angle, at most a few times the solid angle of the short GRB jet. The event rate density of these X-ray transients is around a few tens of {{Gpc}}-3 {{yr}}-1 for luminosity above 1045 {erg} {{{s}}}-1. We predict that future X-ray telescopes (such as Einstein Probe) with sensitivity ∼ {10}-11 {erg} {{{s}}}-1 {{cm}}-2 would detect as many as several tens of such transients per year per steradian. Within 200 Mpc, the aLIGO average range for NS–NS mergers, the estimated event rate of these transients is about 1 transient per year all sky.

  14. Luminosity Functions Of Xxl Clusters Galaxies

    NASA Astrophysics Data System (ADS)

    Ricci, Marina; Maurogordato, Sophie; Benoist, Christophe; XXL Consortium

    2017-06-01

    The galaxy luminosity function (LF) is a powerful statistical tool to investigate galaxy evolution. In particular the study of cluster galaxies LFs gives information about environmental effects and how galaxies populate their parent dark matter halos. In this poster we present our work on the galaxy LF of X-ray detected galaxy clusters from the XXL survey. The sample consists of 173 galaxy groups/clusters spanning a wide range in both mass (M500 from 1013 to 1015 solar masses ) and redshit (0.03 < z < 1.22). The main goal is to investigate the effect of evolution and cluster masses on the luminosity distribution of cluster galaxies.

  15. The Luminosity Function of QSO Host Galaxies

    NASA Technical Reports Server (NTRS)

    Hamilton, Timothy S.; Casertano, Stefano; Turnshek, David A.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present some results from our HST archival image study of 71 QSO host galaxies. The objects are selected to have z less than or equal to 0.46 and total absolute magnitude M(sub v) less than or equal to -23 in our adopted cosmology (H(sub 0) = 50 kilometers per second Mpc(sup-1), q(sub 0) = 0.5, lambda = 0)). The aim of this initial study is to investigate the composition of the sample with respect to host morphology and radio loudness, as well as derive the QSO host galaxy luminosity function. We have analyzed available WFPC2 images in R or I band (U in one case), using a uniform set of procedures. The host galaxies span a narrow range of luminosities and are exceptionally bright, much more so than normal galaxies, usually L greater than L*(sub v). The QSOs are almost equally divided among three subclasses: radio-loud QSOs with elliptical hosts, radio-quiet QSOs with elliptical hosts, and radio-quiet QSOs with spiral hosts. Radio-loud QSOs with spiral hosts are extremely rare. Using a weighting procedure, we derive the combined luminosity function of QSO host galaxies. We find that the luminosity function of QSO hosts differs in shape from that of normal galaxies but that they coincide at the highest luminosities. The ratio of the number of quasar hosts to the number of normal galaxies at a luminosity L*(sub v) is R = (Lv/11.48L*(sub v))(sup 2.46), where L*(sub v) corresponds to M*(sub v)= -22.35, and a QSO is defined to be an object with total nuclear plus host light M(sub v) less than or equal to -23. This ratio can be interpreted as the probability that a galaxy with luminosity L(sub V) will host a QSO at redshift z approximately equal to 0.26.

  16. Luminosity functions for very low mass stars and brown dwarfs

    NASA Technical Reports Server (NTRS)

    Laughlin, Gregory; Bodenheimer, Peter

    1993-01-01

    A theoretical investigation of the luminosity function for low-mass objects to constrain the stellar initial mass function at the low-mass end is reported. The ways in which luminosity functions for low-mass stars are affected by star formation histories, brown dwarf and premain-sequence cooling rates and main-sequence mass luminosity relations, and the IMF are examined. Cooling rates and the mass-luminosity relation are determined through a new series of evolutionary calculations for very low mass stars and brown dwarfs in the range 0.05-0.50 solar mass. Model luminosity functions are constructed for specific comparison with the results of four recent observational surveys. The likelihood that the stellar mass function in the solar neighborhood is increasing at masses near the bottom of the main sequence and perhaps at lower masses is confirmed. In the most optimistic case, brown dwarfs contribute half of the local missing disk mass. The actual contribution is likely to be considerably less.

  17. EVOLUTION OF THE Halpha LUMINOSITY FUNCTION

    SciTech Connect

    Westra, Eduard; Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G.; Dell'Antonio, Ian

    2010-01-01

    The Smithsonian Hectospec Lensing Survey (SHELS) is a window on the star formation history over the last 4 Gyr. SHELS is a spectroscopically complete survey for R{sub tot} < 20.3 over 4 square{sup 0}. We use the 10k spectra to select a sample of pure star-forming galaxies based on their Halpha emission line. We use the spectroscopy to determine extinction corrections for individual galaxies and to remove active galaxies in order to reduce systematic uncertainties. We use the large volume of SHELS with the depth of a narrowband survey for Halpha galaxies at z approx 0.24 to make a combined determination of the Halpha luminosity function at z approx 0.24. The large area covered by SHELS yields a survey volume big enough to determine the bright end of the Halpha luminosity function from redshift 0.100 to 0.377 for an assumed fixed faint-end slope alpha = -1.20. The bright end evolves: the characteristic luminosity L* increases by 0.84 dex over this redshift range. Similarly, the star formation density increases by 0.11 dex. The fraction of galaxies with a close neighbor increases by a factor of 2-5 for L{sub Ha}lpha approx> L* in each of the redshift bins. We conclude that triggered star formation is an important influence for star-forming galaxies with Halpha emission.

  18. Avoiding Spurious Breaks in Binned Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Cara, M.; Lister, M. L.

    2008-10-01

    We show that using either the method of Page & Carrera or the well-known 1/Va method to construct the binned luminosity function (LF) of a flux limited sample of active galactic nuclei (AGNs) can produce an artificial flattening (or steepening in the case of negative evolution) of the binned LF for bins intersected by the flux cutoff of the sample. This effect is more pronounced for samples with steep and strongly evolving parent LFs but is still present even for non-evolving LFs. As a result of this distortion of the true LF, fitting a model LF to binned data may lead to errors in the estimation of the parameters and may even prompt the erroneous use of broken power-law functions. We compute the expected positions of apparent breaks in the binned LF. We show that these spurious breaks in the binned LFs can be avoided if the binning is done in the flux-redshift plane instead of the typically used luminosity-redshift plane. Binning in the flux-redshift plane can be used in conjunction with the binning in the luminosity-redshift plane to test for real breaks in the binned LFs and to identify the features that are the result of binning biases. We illustrate this effect for most typical forms of luminosity dependence and redshift evolution and show how the proposed method helps address this problem. We also apply this method to the MOJAVE AGN sample and show that it eliminates an apparent break in the binned LF.

  19. THE H{alpha} LUMINOSITY FUNCTION AND STAR FORMATION RATE VOLUME DENSITY AT z = 0.8 FROM THE NEWFIRM H{alpha} SURVEY

    SciTech Connect

    Ly Chun; Lee, Janice C.; Momcheva, Ivelina; Dale, Daniel A.; Staudaher, Shawn; Moore, Carolynn A.; Salim, Samir; Finn, Rose

    2011-01-10

    We present new measurements of the H{alpha} luminosity function (LF) and star formation rate (SFR) volume density for galaxies at z {approx} 0.8. Our analysis is based on 1.18 {mu}m narrowband data from the NEWFIRM H{alpha} (NewH{alpha}) Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth ({approx}1.9 x 10{sup -17} erg s{sup -1} cm{sup -2} in H{alpha} at 3{sigma}) and areal coverage (0.82 deg{sup 2}) of the 1.18 {mu}m observations complements other recent H{alpha} studies at similar redshifts, and enables us to minimize the impact of cosmic variance and place robust constraints on the shape of the LF. The present sample contains 818 NB118 excess objects, 394 of which are selected as H{alpha} emitters. Optical spectroscopy has been obtained for 62% of the NB118 excess objects. Empirical optical broadband color classification is used to sort the remainder of the sample. A comparison of the LFs constructed for the four individual fields covered by the observations reveals significant cosmic variance, emphasizing that multiple, widely separated observations are required for such analyses. The dust-corrected LF is well described by a Schechter function with L{sub *} = 10{sup 43.00{+-}0.52} erg s{sup -1}, {Phi}{sub *} = 10{sup -3.20{+-}0.54} Mpc{sup -3}, and {alpha} = -1.6 {+-} 0.19. We compare our H{alpha} LF and SFR density to those at z {approx}< 1, and find a rise in the SFR density {proportional_to}(1 + z){sup 3.4}, which we attribute to significant L{sub *} evolution. Our H{alpha} SFR density of 10{sup -1.00{+-}0.18} M{sub sun} yr{sup -1} Mpc{sup -3} is consistent with UV and [O II] measurements at z {approx} 1. We discuss how these results compare to other H{alpha} surveys at z {approx} 0.8, and find that the different methods used to determine survey completeness can lead to inconsistent results. This suggests that future surveys

  20. Luminosity Function of Faint Globular Clusters in M87

    SciTech Connect

    Waters, Christopher Z.; Zepf, Stephen E.; Lauer, Tod R.; Baltz, Edward A.; Silk, Joseph; /Oxford U.

    2006-07-14

    We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit 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 rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. We also find that the mass-size relation has very little slope, indicating that there is almost no increase in the size of a cluster with increasing mass.

  1. Untangling the White Dwarf Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Lam, M. C.

    2017-03-01

    The inversion of the white dwarf luminosity function provides an independent way to prove the past star formation history of the Milky Way independent of any cosmological models. In Rowell & Hambly (2011), the effective volume method uses the average properties of all the objects in a given bin, so a significant amount of information is lost in the early stage of the analysis. In this work, I explore the possibility of assigning objects individually in a probabilistic way using the generalised Schmidt density estimator (1/Vmax).

  2. NLC Luminosity as a Function of Beam Parameters

    SciTech Connect

    Nosochkov, Yuri

    2002-06-06

    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.

  3. Electromagnetic luminosity function of superconducting cosmic string loops

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Pijushpani

    1988-08-01

    The luminosity function (LF) of electromagnetically radiating closed loops of superconducting cosmic strings (SCS) is calculated in a cosmological context. The LF has a peak as a function of luminosity and a cutoff at the low-luminosity end, and increases with increasing redshift. Some questions concerning a hypothetical model of quasars in which SCS loops act as the ``central engines'' are discussed.

  4. NLC Luminosity as a Function of Beam Parameters

    NASA Astrophysics Data System (ADS)

    Nosochkov, Y.

    2002-06-01

    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.

  5. Galaxy luminosity functions in WINGS clusters

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Aims: 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 facilitating the study of an unbiased sample of clusters with different characteristics. Methods: 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 × 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. Results: The double Schechter fit parameters are correlated neither 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 those derived from large surveys, such as the SDSS. Early-type galaxies out number late-types at all magnitudes, but both early and late types contribute equally to the faint end of the LF. Finally, the spectroscopic LF is in excellent agreement with the one derived for A2199, A85 and Virgo, and with the photometric LF at the bright magnitudes (where both are available). Conclusions: There is a large spread in the LF of different clusters, however, this spread is not caused by correlation of the LF shape with cluster characteristics such as X-ray luminosity or velocity dispersions. The faint end is flatter than previously derived (αf = -1.7), which is at odds with that predicted from numerical simulations. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile. Progs. ID 67.A-0030, 68.A-0139, and 69.A-0119.Table 1 and full Fig. 1 (Fig. A.1) are available in

  6. Interpreting the H II Region Luminosity Function

    NASA Astrophysics Data System (ADS)

    Oey, M. S.; Clarke, C. J.

    1998-12-01

    We construct Monte Carlo simulations of the H II region luminosity function (H II LF), drawing ionizing stars from a constant stellar IMF, and the number of ionizing stars from a power-law distribution of constant slope. We find that observed variations in the form of the H II LF across the Hubble sequence can be explained by a trend in the maximum number of ionizing stars per nebula. In addition, variations in the form of the H II LF between arm and interarm populations of spiral galaxies can be explained by evolutionary effects. The H II LF can thus reveal features in the most recent (< 10 Myr) star formation history of the host galaxies.

  7. Protostellar Luminosity Functions in 11 Diverse Star Forming Environments

    NASA Astrophysics Data System (ADS)

    Kryukova, Erin; Megeath, S. T.; Gutermuth, R.; Pipher, J.; Allen, T. S.; Allen, L. E.; Myers, P. C.; Muzerolle, J.; Cygnus-X Legacy Team

    2012-01-01

    Protostars exist in a variety of environments, ranging from clouds with dispersed low-mass stars, such as Taurus, to clustered regions in clouds forming high-mass stars, like Orion. The effect these different environments have on protostar properties such as mass or luminosity is uncertain. One way to probe the effects of cloud environment on the observable property, protostar luminosity is to compare protostellar luminosity functions of clouds hosting varied populations of protostars. In this dissertation talk I will discuss the protostellar luminosity functions from 11 star forming clouds including Lupus, Chamaeleon, Ophiuchus, Perseus, Serpens, Orion, Cep OB3, Mon R2, Cygnus-X, and Maddalena's Cloud, which encompass a wide range of star forming environments. The luminosity functions are constructed from Spitzer surveys of these molecular clouds. I employ a new technique for estimating the bolometric luminosity from near and mid-IR fluxes alone and for subtracting contamination from galaxies, reddened pre-main sequence stars with disks, and edge-on disk systems. The clouds which are forming massive stars show a significant peak at low luminosity and a tail extending toward luminosities above 10 solar luminosities, while the luminosity functions of clouds which are not forming massive stars have no significant peak down to the sensitivity limit and do not exhibit the tail. I compare these luminosity functions to existing models of protostellar evolution. I also compare the luminosity functions of protostars in distributed and clustered environments, as determined using nearest-neighbor distances. In Orion and Cygnus-X, the clouds which contain the largest populations of protostars there is a clear difference in luminosity functions between protostars incrowded and distributed regions, with the luminosity function biased towards higher luminosities in more luminous regions. I will discuss the implications of these variations and the possibility that the IMF is

  8. The pulse luminosity function of Swift gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Amaral-Rogers, A.; Willingale, R.; O'Brien, P. T.

    2017-01-01

    The complete Swift Burst Alert Telescope and X-Ray Telescope light curves of 118 gamma-ray bursts (GRBs) with known redshifts were fitted using the physical model of GRB pulses by Willingale et al. to produce a total of 607 pulses. We compute the pulse luminosity function utilizing three GRB formation rate models: a progenitor that traces the cosmic star formation rate density (CSFRD) with either a single population of GRBs, coupled to various evolutionary parameters, or a bimodal population of high- and low-luminosity GRBs; and a direct fit to the GRB formation rate excluding any a priori assumptions. We find that a single population of GRB pulses with an evolving luminosity function is preferred over all other univariate evolving GRB models, or bimodal luminosity functions in reproducing the observed GRB pulse L-z distribution and that the magnitude of the evolution in brightness is consistent with studies that utilize only the brightest GRB pulses. We determine that the appearance of a GRB formation rate density evolution component is an artefact of poor parametrization of the CSFRD at high redshifts rather than indicating evolution in the formation rate of early epoch GRBs. We conclude that the single brightest region of a GRB light curve holds no special property; by incorporating pulse data from the totality of GRB emission we boost the GRB population statistics by a factor of 5, rule out some models utilized to explain deficiencies in GRB formation rate modelling, and constrain more tightly some of the observed parameters of GRB behaviour.

  9. Mass Accretion Rate of Very Low Luminosity Objects

    NASA Astrophysics Data System (ADS)

    Sung, Ren-Shiang; Lai, Shih-Ping; Hsieh, Tien-Hao

    2013-08-01

    We propose to measure the mass accretion rate of six Very Low Luminosity Objects (VeLLOs) using Near-infrared Integral Spectrometer (NIFS). The extremely low luminosity of VeLLOs, L_int ≤ 0.1 L_⊙, was previously thought not existing in the nature because the typical accretion rate gives much larger accretion luminosity even for the lowest mass star (``Luminosity Problem''). The commonly accepted solution is that the accretion rate is not constant but episodic. Thus, VeLLOs could be interpreted as protostars being in the quiescent phase of accretion activities. However, there is no observational data directly measuring the mass accretion rate of VeLLOs. The main goal of this proposal is to examine such theory and directly measure the mass accretion rate of VeLLOs for the first time. We propose to measure the blue continuum excess (veiling) of the stellar spectrum, which is the most reliable method for measuring the accretion rate. The measurements have to be made in infrared due to the very high extinction for highly embedded protostars. Our proposal provide a first opportunity to explain the long time ``Luminosity Problem'' through the observational aspects, and Gemini is the only instrument that can provide accurate and high sensitivity infrared spectroscopy measurements within reasonably short time scale.

  10. a New Luminosity Function for Galaxies as Given by the Mass-Luminosity Relationship

    NASA Astrophysics Data System (ADS)

    Zaninetti, Lorenzo

    2008-04-01

    The search for a luminosity function for galaxies both alternative or companion to a Schechter function is a key problem in the reduction of data from catalogs of galaxies. Two luminosity functions for galaxies can be built starting from two distributions of mass as given by the fragmentation. A first overall distribution function is the Kiang function, which represents a useful description of the area and volume distribution of the Poisson Voronoi diagrams. The second distribution, which covers the case of low-mass galaxies, is the truncated Pareto distribution: in this model we have a natural bound due to the minimum mass/luminosity observed and an upper bound (function of the considered environment) represented by the boundary with the observed mass/luminosity overall behavior. The mass distribution is then converted into a luminosity distribution through a standard mass-luminosity relationship. The mathematical rules to convert the probability density function are used and the two new functions are normalized to the total number of galaxies per unit volume. The test of the two new luminosity functions for galaxies that cover different ranges in magnitude was made on the Sloan Digital Sky Survey (SDSS) in five different bands; the results are comparable to those of the Schechter function. A new parameter, which indicates the stellar content, is derived. The joint distribution in redshift and flux, the mean redshift and the number density connected with the first luminosity function for galaxies are obtained by analogy with the Schechter function. A new formula, which allows us to express the mass as a function of the absolute magnitude, is derived.

  11. Luminosity enhancement in relativistic jets and altered luminosity functions for beamed objects

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Shafer, R. A.

    1983-01-01

    Due to relativistic effects, the observed emission from relativistic jets is quite different from the rest frame emission. Systematic differences between the observed and intrinsic intensities of sources in which jet phenomena are occurring are discussed. Assuming that jets have a power law luminosity function of a slope B, the observed luminosity distribution as a function of the velocity of the jet, the spectral index of the rest frame emission, and the range of angles of the jets relative to our line of sight are calculated. The results is well-approximated by two power laws, the higher luminosity end having the original power law index X and the lower luminosity end having a flattened exponent independent of B and only slightly greater than 1. A model consisting of beamed emission from a jet and unbeamed emission from a stationary central component is investigated. The luminosity functions for these two-component sources are calculated for two ranges of angles. For sources in which beaming is important, the luminosity function is much flatter. Because of this, the relative numbers of ""beamed'' and ""unbeamed'' sources detected on the sky depend strongly on the luminosity at which the comparison is made.

  12. Cosmological tests with the FSRQ gamma-ray luminosity function

    NASA Astrophysics Data System (ADS)

    Zeng, Houdun; Melia, Fulvio; Zhang, Li

    2016-11-01

    The extensive catalogue of gamma-ray selected flat-spectrum radio quasars (FSRQs) produced by 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 Λ cold dark matter (ΛCDM) and Rh = 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 ΛCDM and Rh = ct. Regardless of which GLF one chooses, however, we also show that model selection tools very strongly favour Rh = ct over ΛCDM. We suggest that such population studies, though featuring a strong evolution in redshift, may none the less be used as a valuable independent check of other model comparisons based solely on geometric considerations.

  13. THE EVOLUTION OF THE FAR-UV LUMINOSITY FUNCTION AND STAR FORMATION RATE DENSITY OF THE CHANDRA DEEP FIELD SOUTH FROM z = 0.2 TO 1.2 WITH SWIFT/UVOT

    SciTech Connect

    Hagen, Lea M. Z.; Gronwall, Caryl; Wolf, Christopher; Siegel, Michael H.; Hagen, Alex; Hoversten, Erik A.; Page, Mathew

    2015-08-01

    We use deep Swift UV/Optical Telescope (UVOT) near-ultraviolet (1600–4000 Å) imaging of the Chandra Deep Field South to measure the rest-frame far-UV (FUV; 1500 Å) luminosity function (LF) in four redshift bins between z = 0.2 and 1.2. Our sample includes 730 galaxies with u < 24.1 mag. We use two methods to construct and fit the LFs: the traditional V{sub max} method with bootstrap errors, and a maximum likelihood estimator. We observe luminosity evolution such that M* fades by ∼2 mag from z ∼ 1 to z ∼ 0.3, implying that star formation activity was substantially higher at z ∼ 1 than today. We integrate our LFs to determine the FUV luminosity densities and star formation rate densities (SFRDs) from z = 0.2 to 1.2. We find evolution consistent with an increase proportional to (1 + z){sup 1.9} out to z ∼ 1. Our luminosity densities and star formation rates are consistent with those found in the literature but are, on average, a factor of ∼2 higher than previous FUV measurements. In addition, we combine our UVOT data with the MUSYC survey to model the galaxies’ ultraviolet-to-infrared spectral energy distributions and estimate the rest-frame FUV attenuation. We find that accounting for the attenuation increases the SFRDs by ∼1 dex across all four redshift bins.

  14. The Luminosity Function and Star Formation Rate between Redshifts of 0.07 and 1.47 for Narrowband Emitters in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malkan, Matt A.; Kashikawa, Nobunari; Shimasaku, Kazuhiro; Doi, Mamoru; Nagao, Tohru; Iye, Masanori; Kodama, Tadayuki; Morokuma, Tomoki; Motohara, Kentaro

    2007-03-01

    SDF line-emitting galaxies in four narrowband filters at low and intermediate redshifts are presented. Broadband colors, follow-up optical spectroscopy, and multiple NB filters are used to distinguish Hα, [O II], and [O III] emitters at z=0.07-1.47 to construct their LFs. These LFs are derived down to faint magnitudes, allowing for an accurate determination of the faint-end slope. With a large (N~200-900) sample for each redshift interval, a Schechter profile is fitted to each LF. Prior to dust extinction corrections, the [O III] and [O II] LFs agree reasonably well with those of Hippelein et al. The z=0.08 Hα LF, which reaches 2 orders of magnitude fainter than Gallego et al., is steeper by 25%. This indicates that there are more low-luminosity star-forming galaxies for z<0.1. The faint-end slope α and φ* show a strong redshift evolution, while L* shows little evolution. The evolution in α indicates that low-luminosity galaxies have a stronger evolution compared to brighter ones. Integrated SFR densities are derived via Hα, [O III], and [O II] for 0.07function of redshift, is seen for 0.41, the SFR densities are similar. The latter is consistent with previous UV and [O II] measurements. Below z<0.4, the SFR densities are consistent with several Hα, [O II], and UV measurements, but others are a factor of 2 higher. For example, the z=0.066-0.092 LF agrees with Jones & Bland-Hawthorn, but at z=0.24 and 0.40, their number densities are twice as high. This discrepancy can be explained by cosmic variance. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  15. The Local [C ii] 158 μm Emission Line Luminosity Function

    NASA Astrophysics Data System (ADS)

    Hemmati, Shoubaneh; Yan, Lin; Diaz-Santos, Tanio; Armus, Lee; Capak, Peter; Faisst, Andreas; Masters, Daniel

    2017-01-01

    We present, for the first time, the local [C ii] 158 μm emission line luminosity function measured using a sample of more than 500 galaxies from the Revised Bright Galaxy Sample. [C ii] luminosities are measured from the Herschel PACS observations of the Luminous Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey and estimated for the rest of the sample based on the far-infrared (far-IR) luminosity and color. The sample covers 91.3% of the sky and is complete at S60 μm > 5.24 Jy. We calculate the completeness as a function of [C ii] line luminosity and distance, based on the far-IR color and flux densities. The [C ii] luminosity function is constrained in the range ∼107–9 L⊙ from both the 1/Vmax and a maximum likelihood methods. The shape of our derived [C ii] emission line luminosity function agrees well with the IR luminosity function. For the CO(1-0) and [C ii] luminosity functions to agree, we propose a varying ratio of [C ii]/CO(1-0) as a function of CO luminosity, with larger ratios for fainter CO luminosities. Limited [C ii] high-redshift observations as well as estimates based on the IR and UV luminosity functions are suggestive of an evolution in the [C ii] luminosity function similar to the evolution trend of the cosmic star formation rate density. Deep surveys using the Atacama Large Millimeter Array with full capability will be able to confirm this prediction.

  16. Applying the luminosity function statistics in the fireshell model

    NASA Astrophysics Data System (ADS)

    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).

  17. COMPARING SYMBIOTIC NEBULAE AND PLANETARY NEBULAE LUMINOSITY FUNCTIONS

    SciTech Connect

    Frankowski, Adam; Soker, Noam E-mail: soker@physics.technion.ac.i

    2009-10-01

    We compare the observed symbiotic nebulae (SyN) luminosity function (SyNLF) in the [O III] lambda5007 A line to the planetary nebulae (PN) luminosity function (PNLF) and find that the intrinsic SyNLF (ISyNLF) of galactic SyNs has-within its uncertainty of 0.5-0.8 mag-very similar cutoff luminosity and general shape to those of the PNLF. The [O III]/(Halpha+[N II]) line ratios of SyNs and PNs are shown to be also related. Possible implications of these results for the universality of the PNLF are briefly outlined.

  18. The connection between galaxy environment and the luminosity function slopes of star-forming regions

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We present the first study of GALEX far-ultraviolet (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 artefact of varying detection limits for galaxies at different distances.

  19. The Luminosity Dependence of the Galaxy Merger Rate

    NASA Astrophysics Data System (ADS)

    Patton, D. R.; Atfield, J. E.

    2008-09-01

    We measure the number of companions per galaxy (Nc) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey and the Croton and coworkers semianalytic catalog applied to the Millennium Run simulation. For close pairs with projected separations of 5-20 h-1 kpc, velocity differences less than 500 km s-1, and luminosity ratios between 1:2 and 2:1, we find good agreement between the observations and simulations, with Nc consistently close to 0.02 over the range -22 < Mr < - 18. For larger pair separations, Nc(Mr) instead becomes increasingly steep toward the faint end, implying that luminosity-dependent clustering plays an important role on small scales. Using the simulations to assess and correct for projection effects, we infer that the real-space Nc(Mr) for close pairs peaks at about M* and declines by at least a factor of 2 as Mr becomes fainter. Conversely, by measuring the number density of close companions, we estimate that at least 90% of all major mergers occur between galaxies which are fainter than L*. Finally, measurements of the luminosity density of close companions indicate that L* galaxies likely dominate in terms of the overall importance of major mergers in the evolution of galaxy populations at low redshift.

  20. The bright end of the luminosity function at z ~ 9

    NASA Astrophysics Data System (ADS)

    Laporte, N.; Pelló, R.; Hayes, M.; Schaerer, D.; Boone, F.; Richard, J.; Le Borgne, J. F.; Kneib, J. P.; Combes, F.

    2012-06-01

    Context. We present additional constraints on the galaxy luminosity function at z ~ 9 based on observations carried out with ESO/VLT FORS2, HAWK-I, and X-Shooter around the lensing cluster A2667, as part of our project designed to select z ~ 7-10 candidates accessible to spectroscopy. We find that only one selected J-dropout source in this field fulfills the color and magnitude criteria. This source was recently confirmed as a mid-z interloper based on X-Shooter spectroscopy. Aims: Owing to the considerable depth and area covered by our survey, we are able to set strong constraints on the bright end of the galaxy luminosity function and hence on the star formation history at very high redshift. Methods: We used our non-detection of reliable J-dropout sources over the ~36 arcmin2 field of view towards A2667 to carefully determine the lens-corrected effective volume and the corresponding upper limit to the density of sources. Results: Our strongest limit is obtained for Φ(M1500 = -21.4 ± 0.50) < 6.70 × 10-6 Mpc-3 mag-1 at z ~ 9. A maximum-likelihood fit of the luminosity function to all available data points including the present new result yields M⋆ > -19.7 with fixed α = -1.74 and Φ⋆ = 1.10 × 10-3 Mpc-3. The corresponding star-formation rate density should be ρSFR < 5.97 × 10-3 M⊙ yr-1 Mpc3 at z ~ 9. These results are in good agreement with the most recent estimates already published for this range of redshift and luminosity domain. Conclusions: This new result confirms previously measured decreases in the density of luminous galaxies at very high redshift, hence provides strong constraints on the design of future surveys aiming to explore the very high-redshift Universe. Based on observations collected at The European Southern Observatory, Paranal, Chile, as part of the ESO 082.A-0163 and 087.A-0118.

  1. Luminosity function and jet structure of Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    Pescalli, A.; Ghirlanda, G.; Salafia, O. S.; Ghisellini, G.; Nappo, F.; Salvaterra, R.

    2015-02-01

    The structure of gamma-ray burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1046-48 erg s-1) and high (i.e. with L ≥ 1050 erg s-1) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1048-50 erg s-1). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the jet is relatively strongly structured, i.e. E ∝ θ-k with k ≥ 4. The classical E ∝ θ-2 structured jet model is excluded by the current data.

  2. The most luminous z ∼ 9-10 galaxy candidates yet found: The luminosity function, cosmic star-formation rate, and the first mass density estimate at 500 Myr

    SciTech Connect

    Oesch, P. A.; Illingworth, G. D.; Magee, D.; Van Dokkum, P. G.; Momcheva, I.; Ashby, M. L. N.; Fazio, G. G.; Huang, J.-S.; Willner, S. P.; Gonzalez, V.; Trenti, M.; Brammer, G. B.; Skelton, R. E.; Spitler, L. R.

    2014-05-10

    We present the discovery of four surprisingly bright (H {sub 160} ∼ 26-27 mag AB) galaxy candidates at z ∼ 9-10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z ∼ 10 galaxy candidates that are known, just ∼500 Myr after the big bang. Two similarly bright sources are also detected in a reanalysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5σ-6.2σ in the very deep Spitzer/IRAC 4.5 μm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6 μm (6.9σ), revealing a flat UV spectral energy distribution with a slope β = –2.0 ± 0.2, consistent with demonstrated trends with luminosity at high redshift. Thorough testing and use of grism data excludes known low-redshift contamination at high significance, including single emission-line sources, but as-yet unknown low redshift sources could provide an alternative solution given the surprising luminosity of these candidates. Finding such bright galaxies at z ∼ 9-10 suggests that the luminosity function for luminous galaxies might evolve in a complex way at z > 8. The cosmic star formation rate density still shows, however, an order-of-magnitude increase from z ∼ 10 to z ∼ 8 since the dominant contribution comes from low-luminosity sources. Based on the IRAC detections, we derive galaxy stellar masses at z ∼ 10, finding that these luminous objects are typically 10{sup 9} M {sub ☉}. This allows for a first estimate of the cosmic stellar mass density at z ∼ 10 resulting in log{sub 10} ρ{sub ∗}=4.7{sub −0.8}{sup +0.5} M {sub ☉} Mpc{sup –3} for galaxies brighter than M {sub UV} ∼ –18. The remarkable brightness, and hence luminosity, of these z ∼ 9-10 candidates will enable deep spectroscopy to determine their redshift and nature, and highlights the opportunity for the James Webb Space Telescope to map the buildup of

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

    SciTech Connect

    DiPompeo, M. A.; Myers, A. D.; Brotherton, M. S.; Runnoe, J. C.; Green, R. F.

    2014-05-20

    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.

  4. 1. 4 gigahertz luminosity function and its evolution

    SciTech Connect

    Condon, J. J.

    1989-03-01

    The local luminosity function was determined at v = 1.4 GHz from radio observations of two low-redshift galaxy samples: (1) spiral and irregular galaxies with apparent blue magnitudes and declinations and (2) galaxies of all morphologies with blue angular diameters of 1.0 arcmin or greater in the declination range between -2.5 deg and +82 deg. Separate luminosity functions for the radio source populations powered by 'starbursts' and 'monsters' were obtained from the latter sample. The amount of evolution required for the local luminosity function to account for the faint sources is discussed. The cosmological evolution of extragalactic radio sources appears to be so strong at all observed luminosities that the local luminosity function and counts of all sources between S of roughly 10 micro-Jy and S of roughly 10 Jy at v = 1.4 GHz can be matched with a model in which most sources are confined to a hollow shell with z of roughly 0.8. 36 refs.

  5. The K-band luminosity functions of cluster galaxies

    NASA Astrophysics Data System (ADS)

    De Propris, Roberto

    2017-03-01

    We derive the galaxy luminosity function in the Ks band for galaxies in 24 clusters to provide a local reference for higher redshift studies and to analyse how and if the luminosity function varies according to environment and cluster properties. We use new, deep K-band imaging and match the photometry to available redshift information and to optical photometry from the SDSS or the UKST/POSS: More than 80 per cent of the galaxies to K ∼ 14.5 have measured redshifts. We derive composite luminosity functions, for the entire sample and for cluster subsamples. We consider the luminosity functions for red-sequence and blue cloud galaxies. The full composite luminosity function has K* = 12.79 ± 0.14 (MK = -24.81) and α = -1.41 ± 0.10. We find that K* is largely unaffected by the environment, but that the slope α increases towards lower mass clusters and clusters with Bautz-Morgan type < II. The red-sequence luminosity function seems to be approximately universal (within errors) in all environments: It has parameters K* = 13.16 ± 0.15 (MK = -24.44) and α = -1.00 ± 0.12 (for all galaxies). Blue galaxies do not show a good fit to a Schechter function, but the best values for its parameters are K* = 13.51 ± 0.41 (MK = -24.09) and α = -1.60 ± 0.29: We do not have enough statistics to consider environmental variations for these galaxies. We find some evidence that K* in clusters is brighter than in the field and α is steeper, but note that this comparison is based (for the field) on 2MASS photometry, while our data are considerably deeper.

  6. The luminosity function of galaxies in compact groups

    NASA Technical Reports Server (NTRS)

    Ribeiro, A. L. B.; De Carvalho, R. R.; Zepf, S. E.

    1994-01-01

    We use counts of faint galaxies in the regions of compact groups to extend the study of the luminosity function of galaxies in compact groups to absolute magnitudes as faint as M(sub B) = -14.5 + 5 log h. We find a slope of the faint end of the luminosity function of approximately alpha = -0.8, with a formal uncertainty of 0.15. This slope is not significantly different from that found for galaxies in other environments. Our results do not support previous suggestions of a dramatic underabundance of intrinsically faint galaxies in compact groups, which were based on extrapolations from fits at brighter magnitudes. The normal faint-end slope of the luminosity function in compact groups is in agreement with previous evidence that most galaxies in compact groups have not been dramatically affected by recent merging.

  7. Quasar UV luminosity function evolution up to z = 8

    NASA Astrophysics Data System (ADS)

    Manti, S.; Gallerani, S.; Ferrara, A.; Greig, B.; Feruglio, C.

    2017-04-01

    We study the redshift evolution of the quasar (QSO) UV luminosity function (LF) for 0.5 < z < 6.5, by collecting the most up to date observational data and, in particular, the recently discovered population of faint active galactic nuclei (AGNs). We fit the QSO LF using either a double power-law function or a Schechter function, finding that both forms provide good fits to the data. We derive empirical relations for the LF parameters as a function of redshift and, based on these results, predict the QSO UV LF at z = 8. From the inferred LF evolution, we compute the redshift evolution of the QSO/AGN comoving ionizing emissivity and hydrogen photoionization rate. If faint AGNs are included, the contribution of QSOs to reionization increases substantially. However, their level of contribution critically depends on the detailed shape of the QSO LF, which can be constrained by efficient searches of high-z QSOs. To this aim, we predict the expected (i) number of z > 6 QSOs detectable by ongoing and future near-infrared surveys (as EUCLID and Wide-Field Infrared Survey Telescope), and (ii) number counts for a single radio-recombination line observation with Square Kilometre Array-MID (FoV = 0.49 deg2) as a function of the Hnα flux density, at 0 < z < 8. These surveys (even at z < 6) will be fundamental to better constrain the role of QSOs as reionization sources.

  8. Modelling the luminosities and sizes of radio sources: radio luminosity function at z = 6

    NASA Astrophysics Data System (ADS)

    Saxena, A.; Röttgering, H. J. A.; Rigby, E. E.

    2017-08-01

    We present a model to predict the luminosity function for radio galaxies and their linear size distribution at any redshift. The model takes a black hole mass function and Eddington ratio distribution as input and tracks the evolution of radio sources, taking into account synchrotron, adiabatic and inverse Compton energy losses. We first test the model at z = 2 where plenty of radio data are available and show that the radio luminosity function (RLF) is consistent with observations. We are able to reproduce the break in luminosity function that separates locally the Fanaroff-Riley class I and Fanaroff-Riley class I radio sources. Our prediction for linear size distribution at z = 2 matches the observed distribution too. We then use our model to predict an RLF and linear size distribution at z = 6, as this is the epoch when radio galaxies can be used as probes of reionization. We demonstrate that higher inverse Compton losses lead to shorter source lifetimes and smaller sizes at high redshifts. The predicted sizes are consistent with the generally observed trend with redshift. We evolve the z = 2 RLF based on observed quasar space densities at high redshifts, and show that our RLF prediction at z = 6 is consistent. Finally, we predict the detection of 0.63, 0.092 and 0.0025 z ≥ 6 sources deg2 at flux density limits of 0.1, 0.5 and 3.5 mJy. We assess the trade-off between coverage area and depth and show that LOFAR surveys with flux density limits of 0.1 and 0.5 mJy are the most efficient at detecting a large number of z ≥ 6 radio sources.

  9. The faint end of the galaxy luminosity function

    NASA Technical Reports Server (NTRS)

    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.

  10. The Planetary Nebula Luminosity Function at the dawn of Gaia

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin

    2012-09-01

    The [O iii] λ5007 Planetary Nebula Luminosity Function (PNLF) is an excellent extragalactic standard candle. In theory, the PNLF method should not work at all, since the luminosities of the brightest planetary nebulae (PNe) should be highly sensitive to the age of their host stellar population. Yet the method appears robust, as it consistently produces ≲10 % distances to galaxies of all Hubble types, from the earliest ellipticals to the latest-type spirals and irregulars. It is therefore uniquely suited for cross-checking the results of other techniques and finding small offsets between the Population I and Population II distance ladders. We review the calibration of the method and show that the zero points provided by Cepheids and the Tip of the Red Giant Branch are in excellent agreement. We then compare the results of the PNLF with those from Surface Brightness Fluctuation measurements, and show that, although both techniques agree in a relative sense, the latter method yields distances that are ˜15 % larger than those from the PNLF. We trace this discrepancy back to the calibration galaxies and argue that, due to a small systematic error associated with internal reddening, the true distance scale likely falls between the extremes of the two methods. We also demonstrate how PNLF measurements in the early-type galaxies that have hosted Type Ia supernovae can help calibrate the SN Ia maximum magnitude-rate of decline relation. Finally, we discuss how the results from space missions such as Kepler and Gaia can help our understanding of the PNLF phenomenon and improve our knowledge of the physics of local planetary nebulae.

  11. Systematic properties of CO emission from galaxies. I - Luminosity function

    NASA Technical Reports Server (NTRS)

    Verter, Frances

    1987-01-01

    A sensitive survey of normal galaxies covering a wide range of luminosities and morphological types is combined with galaxy observations in the literature to provide a sample for statistical study. The global CO emission of these galaxies is extrapolated by modeling the galaxies with an exponential radial profile. The maximum-likelihood distribution functions of CO luminosity and CO/H I flux ratio are similar in behavior. Both have long tails of bright galaxies. However, the typical galaxy has a CO luminosity of about 10 to the 6th Jy km/s Mpc-squared or less and a CO/H I ratio of the order of 10 or less. Averages of the distributions of CO luminosity and CO/H I flux ratio are higher for galaxies of Hubble type Sb-Sbc than for groups of earlier or later types. Quantitative estimates of the possible error sources in the conversion of CO luminosity to molecular mass indicates that the peaking of CO emission at intermediate types is a fairly confident result.

  12. The Luminosity Functions of Low Redshift Field and Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Jorgensen, I.; Hill, G. J.; Bergmann, M. P.; Elston, R.; Vanden Berk, D.; Jurcevic, J. S.

    1999-12-01

    We present a comparison of the luminosity functions for low redshift field and cluster galaxies. The luminosity functions are established for field galaxies in UBVRI, and for galaxies in the Coma cluster in UBRI. The field galaxy sample is drawn from The Texas Deep Sky Survey (TDSS) of a 2.1 by 2.1 sq. deg. area around the North Galactic Pole. More than 40000 objects have been detected in our survey of this area. We have obtained spectra of approximately 700 galaxies, making the redshift information complete to a total R magnitude of 18.5 mag. We have surveyed the central square degree of the Coma cluster in UBRI. Approximately 16000 objects have been detected in our survey. We have obtained spectra for 220 galaxies in the area with no previous measurements. Together with published data these observations make the redshift information complete for galaxies brighter than a total R magnitude of 17.5. A total of 480 members of the cluster have measured redshifts, while 180 background and foreground galaxies in the field have measured redshifts. The accurate determination of the luminosity functions for low redshift galaxies is important for the interpretation of luminosity functions established for higher redshift galaxies, both in clusters and in the field. This research was supported in part by NASA through grant number HF-01073.01.94A to IJ from the Space Telescope Science Institute.

  13. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    NASA Astrophysics Data System (ADS)

    Loveday, J.; Norberg, P.; Baldry, I. K.; Driver, S. P.; Hopkins, A. M.; Peacock, J. A.; Bamford, S. P.; Liske, J.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

    2012-02-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fitted over a range of more than 10 magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue plus red sample, require double power-law Schechter functions to fit a dip in their LF faintwards of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disc galaxies. We measure the evolution of the galaxy LF over the redshift range 0.002 < z < 0.5 both by using a parametric fit and by measuring binned LFs in redshift slices. The characteristic luminosity L* is found to increase with redshift in all bands, with red galaxies showing stronger luminosity evolution than blue galaxies. The comoving number density of blue galaxies increases with redshift, while that of red galaxies decreases, consistent with prevailing movement from blue cloud to red sequence. As well as being more numerous at higher redshift, blue galaxies also dominate the overall luminosity density beyond redshifts z≃ 0.2. At lower redshifts, the luminosity density is dominated by red galaxies in the riz bands, and by blue galaxies in u and g.

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

    SciTech Connect

    McGreer, Ian D.; Fan Xiaohui; Jiang Linhua; Richards, Gordon T.; Strauss, Michael A.; Ross, Nicholas P.; White, Martin; Shen Yue; Schneider, Donald P.; Brandt, W. Niel; Myers, Adam D.; DeGraf, Colin; Glikman, Eilat; Ge Jian; Streblyanska, Alina

    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.

  15. Probing the Ultraviolet Luminosity Function of the Earliest Galaxies with the Renaissance Simulations

    NASA Astrophysics Data System (ADS)

    O'Shea, Brian W.; Wise, John H.; Xu, Hao; Norman, Michael L.

    2015-07-01

    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˜ 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≤slant -17), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations, and has a clearly defined lower limit in UV luminosity. This behavior of the luminosity function is due to two factors: (i) the strong dependence of the star formation rate (SFR) on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower SFRs and thus lower UV luminosities; and (ii) the fact that halos with virial masses below ≃ 2× {10}8 {M}⊙ do not universally contain stars, with the fraction of halos containing stars dropping to zero at ≃ 7× {10}6 {M}⊙ . Finally, we show that the brightest of our simulated galaxies may be visible to current and future ultra-deep space-based surveys, particularly if lensed regions are chosen for observation.

  16. On the luminosity function, lifetimes, and origin of blue stragglers in globular clusters

    NASA Technical Reports Server (NTRS)

    Bailyn, Charles D.; Pinsonneault, Marc H.

    1995-01-01

    We compute theoretical evolutionary tracks of blue stragglers created by mergers. Two formation scenarios are considered: mergers of primordial binaries, and stellar collisions. These two scenarios predict strikingly different luminosity functions, which are potentially distinguishable observationally. Tabulated theoretical luminosity functions and lifetimes are presented for blue stragglers formed under a variety of input conditions. We compare our results with observations of the blue straggler sequences in 47 Tucanae and M3. In the case of 47 Tuc, the luminosity function and the formation rate are compatible with the hypothesis that the blue stragglers formed through the collision of single stars. Mergers of primordial binaries are only marginally cosistent with the data, and a significant enhancement of the collision cross section by binary-single-star encounters appears to be ruled out. In the case of M3, we find that the innermost blue stragglers have a luminosity function significantly different from that of the outer stragglers, thus confirming earlier suggestions that there are two distinct populations of blue stragglers in this cluster. The inner stragglers are preferentially brighter and bluer, as would be expected if they were made by collisions, but there are so many of them that the collision rate would need to be enhanced by interactions involving wide binaries. The luminosity function of the outer stragglers is almost identical to the predictions of mergers from primordial binaries and is inconsistent with the collision hypothesis.

  17. Disk Luminosity Function Based on the Lowell Proper Motion Survey

    NASA Astrophysics Data System (ADS)

    Kim, Mee-Jeong; Lee, Sang-Gak

    1991-12-01

    Disk stellar luminosity function has been derived with stars in the Lowell Proper Motion Survey which contains about 9000 stars with mu => 0.27" of arc/yr, 8 < m_pg < 17 and with bright stars in the Smithsonian Astrophysical Observatory (SAO) Star Catalogue. Luminosity function has been obtained with stars within 20 pc by Luyten's mean absolute magnitudes method using Reduced Proper Motion Diagram to select disk stars. Magnitudes and colors, in the SAO Star Catalogue as well as in the Lowell Proper Motion Survey have been transformed to the UBV system from the published UBV data. It has been found that stars which have higher proper motion than the original limit of the proper motion survey are missed, when the relation between the absolute magnitude and reduced proper motion is applied to sample stars without considering the dispersion in magnitude. Correction factors for missing stars have been estimated according to their limits of proper motion which are dependent on the absolute magnitude. Resulting lumi- nosity function shows Wielen's dip at M_B ~ 10, and systematic enhancement of stars on the average of about delta log Phi(M_B) ~ 0.2 compared with Luyten's luminosity function.

  18. LUMINOUS SATELLITES. II. SPATIAL DISTRIBUTION, LUMINOSITY FUNCTION, AND COSMIC EVOLUTION

    SciTech Connect

    Nierenberg, A. M.; Treu, T.; Auger, M. W.; Marshall, P. J.; Fassnacht, C. D.; Busha, Michael T.

    2012-06-20

    We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log{sub 10}[M*{sub h}/M{sub Sun }] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R){proportional_to}R{sup {gamma}{sub p}}, we find {gamma}{sub p} = -1.1 {+-} 0.3. We find no dependency of {gamma}{sub p} on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

  19. The CLASS BL Lac sample: the radio luminosity function

    NASA Astrophysics Data System (ADS)

    Marchã, M. J. M.; Caccianiga, A.

    2013-04-01

    This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey). The sample is one of the largest well-defined samples in the low-power regime with a total of 130 sources of which 55 satisfy the `classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the radio luminosity function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the luminosity function which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study, we extend for the first time the BL Lac RLF down to very low radio powers ˜1022 W Hz-1, i.e. two orders of magnitude below the RLF currently available in the literature. In the process, we confirm the importance of adopting a broader, and more physically meaningful set of classification criteria to avoid the systematic missing of low-luminosity BL Lacs. Thanks to the good statistics we confirm the existence of weak but significant positive cosmological evolution for the BL Lac population, and we detect, for the first time the flattening of the RLF at L ˜ 1025 W Hz-1 in agreement with the predictions of the beaming model.

  20. MID-INFRARED GALAXY LUMINOSITY FUNCTIONS FROM THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Dai, X.; Assef, R. J.; Kochanek, C. S.; Brodwin, M.; Dey, A.; Jannuzi, B. T.; Brown, M. J. I.; Caldwell, N.; Jones, C.; Murray, S. S.; Cool, R. J.; Eisenstein, D.; Eisenhardt, P.; Stern, D.; Gonzalez, A. H.

    2009-05-20

    We present galaxy luminosity functions at 3.6, 4.5, 5.8, and 8.0 {mu}m measured by combining photometry from the IRAC Shallow Survey with redshifts from the AGN and Galaxy Evolution Survey (AGES) of the NOAO Deep Wide-Field Survey Booetes field. The well defined IRAC samples contain 3800-5800 galaxies for the 3.6-8.0 {mu}m bands with spectroscopic redshifts and z < 0.6. We obtained relatively complete luminosity functions in the local redshift bin of z < 0.2 for all four IRAC channels that are well fitted by Schechter functions. After analyzing the samples for the whole redshift range, we found significant evolution in the luminosity functions for all four IRAC channels that can be fitted as an evolution in M {sub *} with redshift, {delta}M {sub *} = Qz. While we measured Q = 1.2 {+-} 0.4 and 1.1 {+-} 0.4 in the 3.6 and 4.5 {mu}m bands consistent with the predictions from a passively evolving population, we obtained Q = 1.8 {+-} 1.1 in the 8.0 {mu}m band consistent with other evolving star formation rate estimates. We compared our luminosity functions with the predictions of semianalytical galaxy formation and found the best agreement at 3.6 and 4.5 {mu}m, rough agreement at 8.0 {mu}m, and a large mismatch at 5.8 {mu}m. These models also predicted a comparable Q-value to our luminosity functions at 8.0 {mu}m, but predicted smaller values at 3.6 and 4.5 {mu}m. We also measured the luminosity functions separately for early- and late-type galaxies. While the luminosity functions of late-type galaxies resemble those for the total population, the luminosity functions of early-type galaxies in the 3.6 and 4.5 {mu}m bands indicate deviations from the passive evolution model, especially from the measured flat luminosity density evolution. Combining our estimates with other measurements in the literature, we found 53 {+-} 18% of the present stellar mass of early-type galaxies was assembled at z = 0.7.

  1. Generalized Continuity Equation Solutions for the QSO Luminosity Function

    NASA Astrophysics Data System (ADS)

    Caditz, David M.

    2016-04-01

    We present a generalized continuity equation that describes the relationship between the statistical and physical evolution of populations of astronomical objects. This equation allows us to parameterize the luminosity function (LF) in terms of physically meaningful quantities, such as creation timescale, τs, object evolutionary timescale, τg, and lifetime, am. The shape and evolution of the LF are shown to be sensitive to these physical parameters, with large regions of the parameter space producing relatively simple evolutionary scenarios such as density evolution (DE) or luminosity evolution (LE). Regions of parameter space where τs ≲ 0.3tH and τg ≲ 0.5tH, where tH is the Hubble time, may be characterized by more complex evolution including the natural formation of a double power-law shape and mixed density and luminosity evolution (ME). This result has important consequences for the interpretation of the quasi-stellar object (QSO) LF, implying that the timescales for creation and physical evolution may fall near the above range. A fit to QSO survey data for redshifts 0.68 < z < 4 implies that τs ˜ 0.2tH and τg ˜ 0.05tH with QSOs having a maximum lifetime of am ˜ 0.25tH.

  2. Study of the luminosity function for field galaxies

    NASA Technical Reports Server (NTRS)

    Felten, J. E.

    1977-01-01

    Nine determinations of the luminosity function (LF) for field galaxies are adjusted, analyzed, and compared. Adjustments are made for differences in definitions as well as in assumptions regarding magnitude systems, the Hubble constant, and galactic absorption. Eight of the nine adjusted determinations are found to be in fairly good agreement, and the discrepancy in the ninth is attributed to incompleteness effects. A large-scale normalization of the LF is performed using the method and some integral counts of Gott and Turner (1976); the large-scale mean LF of (mostly field) galaxies is found to be about 2.3 times less than a previously derived 'local' LF. The large-scale luminosity density in space arising from sources within the B(0) isophotes of galaxies is evaluated, and a value of 86 million (H/50) suns per cu Mpc is obtained for a galactic absorption coefficient of 0.25 magnitude. It is noted that the true large-scale luminosity density is probably within a factor of 1.6 of the reported value.

  3. z ~ 1 Lyα Emitters. I. The Luminosity Function

    NASA Astrophysics Data System (ADS)

    Wold, Isak G. B.; Barger, Amy J.; Cowie, Lennox L.

    2014-03-01

    We construct a flux-limited sample of 135 candidate z ~ 1 Lyα emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. These LAEs have luminosities comparable to those at high redshifts and lie within a 7 Gyr gap present in existing LAE samples. We use archival and newly obtained optical spectra to verify the UV redshifts of these LAEs. We use the combination of the GALEX UV spectra, optical spectra, and X-ray imaging data to estimate the active galactic nucleus (AGN) fraction and its dependence on Lyα luminosity. We remove the AGNs and compute the luminosity function (LF) from 60 z ~ 1 LAE galaxies. We find that the best-fit LF implies a luminosity density increase by a factor of ~1.5 from z ~ 0.3 to z ~ 1 and ~20 from z ~ 1 to z ~ 2. We find a z ~ 1 volumetric Lyα escape fraction of 0.7% ± 0.4%. Based in part on data obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. Based in part on zCOSMOS observations carried out using the Very Large Telescope at the ESO Paranal Observatory under Program ID: LP175.A-0839.

  4. The luminosity function of the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, R. O.; Huchra, J. P.; Geller, M. J.

    1994-01-01

    We use the CfA Reshift Survey of galaxies with m(sub z) less than or equal to 15.5 to calculate the galaxy luminosity function over the range -13 less than or equal to M(sub z) less than or equal to -22. The sample includes 9063 galaxies distributed over 2.1 sr. For galaxies with velocities cz greater or equal to 2500 km per sec, where the effects of peculiar velocities are small, the luminosity function is well represented by a Schechter function with parameters phi(sub star) = 0.04 +/- 0.01 per cu Mpc, M(sub star) = -18.8 +/- 0.3, and alpha = -1.0 +/- 0.2. When we include all galaxies with cz greater or equal to 500 km per sec, the number of galaxies in the range -16 less than or equal to M(sub z) less than or equal to -13 exceeds the extrapolation of the Schechter function by a factor of 3.1 +/- 0.5. This faint-end excess is not caused by the local peculiar velocity field but may be partially explained by small scale errors in the Zwicky magnitudes. Even with a scale error as large as 0.2 mag per mag, which is unlikely, the excess is still a factor of 1.8 +/- 0.3. If real, this excess affects the interpretation of deep counts of field galaxies.

  5. A Statistical Method for Estimating Luminosity Functions Using Truncated Data

    NASA Astrophysics Data System (ADS)

    Schafer, Chad M.

    2007-06-01

    The observational limitations of astronomical surveys lead to significant statistical inference challenges. One such challenge is the estimation of luminosity functions given redshift (z) and absolute magnitude (M) measurements from an irregularly truncated sample of objects. This is a bivariate density estimation problem; we develop here a statistically rigorous method which (1) does not assume a strict parametric form for the bivariate density; (2) does not assume independence between redshift and absolute magnitude (and hence allows evolution of the luminosity function with redshift); (3) does not require dividing the data into arbitrary bins; and (4) naturally incorporates a varying selection function. We accomplish this by decomposing the bivariate density φ(z,M) vialogφ(z,M)=f(z)+g(M)+h(z,M,θ), where f and g are estimated nonparametrically and h takes an assumed parametric form. There is a simple way of estimating the integrated mean squared error of the estimator; smoothing parameters are selected to minimize this quantity. Results are presented from the analysis of a sample of quasars.

  6. Feedback from AGN: The Kinetic/Radio Luminosity Function

    NASA Astrophysics Data System (ADS)

    Melini, Gabriele; La Franca, Fabio; Fiore, Fabrizio

    2010-05-01

    We have measured the probability distribution function of the ratio RX = log L1.4/LX, where L1.4/LX = ν Lν(1.4 GHz)/LX(2-10 keV), between the 1.4 GHz and the unabsorbed 2-10 keV luminosities and its dependence on LX and z. We have used a complete sample of ~1800 hard X-ray selected AGN, observed in the 1.4 GHz band, cross-correlated in order to exclude FR II-type objects, and thus obtain a contemporaneous measure of the radio and X-ray emission. The distribution P(RX|LX,z) is shown in Figure 1. Convolution of the distribution P(RX|LX,z) with the 2-10 keV X-ray AGN luminosity function from La Franca et al. (2005) and the relations between radio power and kinetic energy from Best et al. (2006) and Willott et al. (1999) allows us to derive the AGN kinetic power and its evolution. As shown in Figure 1, our results are in good agreement with the predictions of the most recent models of galaxy formation and evolution (e.g., Croton et al. 2006), where AGN radio feedback is required to quench the star formation.

  7. UVUDF: UV Luminosity Functions at the Cosmic High Noon

    NASA Astrophysics Data System (ADS)

    Mehta, Vihang; Scarlata, Claudia; Rafelski, Marc; Gburek, Timothy; Teplitz, Harry I.; Alavi, Anahita; Boylan-Kolchin, Michael; Finkelstein, Steven; Gardner, Jonathan P.; Grogin, Norman; Koekemoer, Anton; Kurczynski, Peter; Siana, Brian; Codoreanu, Alex; de Mello, Duilia F.; Lee, Kyoung-Soo; Soto, Emmaris

    2017-03-01

    We present the rest-1500 Å UV luminosity functions (LF) for star-forming galaxies during the cosmic high noon—the peak of cosmic star formation rate at 1.5< z< 3. We use deep NUV imaging data obtained as part of the Hubble Ultra-Violet Ultra Deep Field (UVUDF) program, along with existing deep optical and NIR coverage on the HUDF. We select F225W, F275W, and F336W dropout samples using the Lyman break technique, along with samples in the corresponding redshift ranges selected using photometric redshifts, and measure the rest-frame UV LF at z∼ 1.7,2.2,3.0, respectively, using the modified maximum likelihood estimator. We perform simulations to quantify the survey and sample incompleteness for the UVUDF samples to correct the effective volume calculations for the LF. We select galaxies down to {M}{UV}=-15.9,-16.3,-16.8 and fit a faint-end slope of α =-{1.20}-0.13+0.10,-{1.32}-0.14+0.10,-{1.39}-0.12+0.08 at 1.4< z< 1.9, 1.8< z< 2.6, and 2.4< z< 3.6, respectively. We compare the star formation properties of z∼ 2 galaxies from these UV observations with results from Hα and UV+IR observations. We find a lack of high-SFR sources in the UV LF compared to the Hα and UV+IR, likely due to dusty SFGs not being properly accounted for by the generic {IRX}{--}β relation used to correct for dust. We compute a volume-averaged UV-to-Hα ratio by abundance matching the rest-frame UV LF and Hα LF. We find an increasing UV-to-Hα ratio toward low-mass galaxies ({M}\\star ≲ 5× {10}9 {M}ȯ ). We conclude that this could be due to a larger contribution from starbursting galaxies compared to the high-mass end.

  8. The X-Ray Background and the AGN Luminosity Function

    NASA Astrophysics Data System (ADS)

    Hasinger, G.

    The deepest X-ray surveys performed with ROSAT were able to resolve as much as 70-80% of the 1-2 keV X-ray background into resolved sources. Optical follow-up observations were able to identify the majority of faint X-ray sources as active galactic nuclei (AGN) out to redshifts of 4.5 as well as a sizeable fraction as groups of galaxies out to redshifts of 0.7. A new population of X-ray luminous, optically innocent narrow emission line galaxies (NELGs) at the faintest X-ray fluxes is still a matter of debate, most likely many of them are also connected to AGN. First deep surveys with the Japanese ASCA satellite give us a glimpse of the harder X-ray background where the bulk of the energy density resides. Future X-ray observatories (XMM and AXAF) will be able to resolve the harder X-ray background. For the first time we are now in a position to study the cosmological evolution of the X-ray luminosity function of AGN, groups of galaxies and galaxies and simultaneously constrain their total luminosity output over cosmic time.

  9. Maximum likelihood random galaxy catalogues and luminosity function estimation

    NASA Astrophysics Data System (ADS)

    Cole, Shaun

    2011-09-01

    We present a new algorithm to generate a random (unclustered) version of an magnitude limited observational galaxy redshift catalogue. It takes into account both galaxy evolution and the perturbing effects of large-scale structure. The key to the algorithm is a maximum likelihood (ML) method for jointly estimating both the luminosity function (LF) and the overdensity as a function of redshift. The random catalogue algorithm then works by cloning each galaxy in the original catalogue, with the number of clones determined by the ML solution. Each of these cloned galaxies is then assigned a random redshift uniformly distributed over the accessible survey volume, taking account of the survey magnitude limit(s) and, optionally, both luminosity and number density evolution. The resulting random catalogues, which can be employed in traditional estimates of galaxy clustering, make fuller use of the information available in the original catalogue and hence are superior to simply fitting a functional form to the observed redshift distribution. They are particularly well suited to studies of the dependence of galaxy clustering on galaxy properties as each galaxy in the random catalogue has the same list of attributes as measured for the galaxies in the genuine catalogue. The derivation of the joint overdensity and LF estimator reveals the limit in which the ML estimate reduces to the standard 1/Vmax LF estimate, namely when one makes the prior assumption that the are no fluctuations in the radial overdensity. The new ML estimator can be viewed as a generalization of the 1/Vmax estimate in which Vmax is replaced by a density corrected Vdc, max.

  10. Relativistic cosmology number densities and the luminosity function

    NASA Astrophysics Data System (ADS)

    Iribarrem, A. S.; Lopes, A. R.; Ribeiro, M. B.; Stoeger, W. R.

    2012-03-01

    Aims: This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaître-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, ApJ, 657, 760), 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, ApJ, 592, 1), further developing the theory linking relativistic cosmology theory and LF data. Methods: Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy LF obtained from an I-band selected dataset of the FORS deep field galaxy survey in the redshift range 0.5 ≤ z ≤ 5.0 for its blue bands and 0.75 ≤ z ≤ 3.0 for its red ones. Differential number counts, densities and other related observables are obtained, and then used with the calculated selection functions to study the empirical radial distribution of the galaxies in a fully relativistic framework. Results: The redshift range of the dataset used in this work, which is up to five times larger than the one used in previous studies, shows an increased relevance of the relativistic effects of expansion when compared to the evolution of the LF at the higher redshifts. The results also agree with the preliminary ones presented in Albani et al., suggesting a power-law behavior of relativistic densities at high redshifts when they are defined in terms of the luminosity distance.

  11. The Herschel Virgo Cluster Survey. I. Luminosity function

    NASA Astrophysics Data System (ADS)

    Davies, J. I.; Baes, M.; Bendo, G. J.; Bianchi, S.; Bomans, D. J.; Boselli, A.; Clemens, M.; Corbelli, E.; Cortese, L.; Dariush, A.; De Looze, I.; di Serego Alighieri, S.; Fadda, D.; Fritz, J.; Garcia-Appadoo, D. A.; Gavazzi, G.; Giovanardi, C.; Grossi, M.; Hughes, T. M.; Hunt, L. K.; Jones, A. P.; Madden, S.; Pierini, D.; Pohlen, M.; Sabatini, S.; Smith, M. W. L.; Verstappen, J.; Vlahakis, C.; Xilouris, E. M.; Zibetti, S.

    2010-07-01

    We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data obtained as part of the science demonstration phase (SDP). The data cover a central 4×4 sq deg region of the cluster. We use SPIRE and PACS photometry data to produce 100, 160, 250, 350 and 500 μm luminosity functions (LFs) for optically bright galaxies that are selected at 500 μm and detected in all bands. We compare these LFs with those previously derived using IRAS, BLAST and Herschel-ATLAS data. The Virgo cluster LFs do not have the large numbers of faint galaxies or examples of very luminous galaxies seen previously in surveys covering less dense environments. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  12. The Galaxy UV Luminosity Function before the Epoch of Reionization

    NASA Astrophysics Data System (ADS)

    Mason, Charlotte A.; Trenti, Michele; Treu, Tommaso

    2015-11-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a mass-dependent, but redshift-independent, efficiency. We introduce a new self-consistent treatment of the halo star formation history, which allows us to make predictions at z > 10 (lookback time ≲500 Myr), when growth is rapid. With a calibration at a single redshift to set the stellar-to-halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all available observations (0 ≲ z ≲ 10). The significant drop in luminosity density of currently detectable galaxies beyond z ˜ 8 is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth τ ={0.056}-0.010+0.007, fully consistent with the latest Planck measurement, implying that the universe is fully reionized at z={7.84}-0.98+0.65. In addition, our model naturally produces smoothly rising star formation histories for galaxies with L ≲ L* in agreement with observations and hydrodynamical simulations. Before the epoch of reionization at z > 10 we predict the LF to remain well-described by a Schechter function, but with an increasingly steep faint-end slope (α ˜ -3.5 at z ˜ 16). Finally, we construct forecasts for surveys with James Webb Space Telescope (JWST) and Wide-field Infrared Survey Telescope (WFIRST) and predict that galaxies out to z ˜ 14 will be observed. Galaxies at z > 15 will likely be accessible to JWST and WFIRST only through the assistance of strong lensing magnification.

  13. Tracing galaxy evolution by their present-day luminosity function

    NASA Astrophysics Data System (ADS)

    Tempel, Elmo

    2011-04-01

    Galaxies, which are complex objects containing up to several tens of billions stars, as well as gas and dust, are remarkable objects. The Universe contains a very diverse "zoo" of galaxies: there are galaxies with a discy shape and spiral structure, elliptical galaxies, and even galaxies, which show no sign of structure. This variety of galaxies leads to the basic question: how the galaxies form and evolve and which processes shape the structure of galaxies? Due to the complexity of galaxy formation and evolution, this question is still an unresolved puzzle and it is one of the biggest challenges in modern cosmology. The present thesis is based on large galaxy surveys and concentrates on the large-scale structure: how galaxy evolution is related to the surrounding large-scale environment of superclusters and voids. To study the evolution of galaxies, we use the luminosity function, which is in this respect one of the most fundamental of all cosmological observables. One of the principal results of the present study was the conclusion that the evolution of spiral galaxies is almost independent of the global environment, especially for blue and red spirals separately, showing that the formation of spiral galaxies has to be similar in all environments. Meanwhile, the luminosity function of elliptical galaxies depends strongly on the environment. This shows that the global environmental density is an important factor (via merging history) in the formation of elliptical galaxies. The results of the present study show clearly, that besides the local/group environment, the global (supercluster-void) environment plays also an important role in the formation and evolution of galaxies. Accounting for the role of global environment can help to solve several problems in the present picture of galaxy formation and evolution.

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

    SciTech Connect

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

    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.

  15. The GRB luminosity function: prediction of the internal shock model and comparison to observations

    NASA Astrophysics Data System (ADS)

    Zitouni, H.; Daigne, F.; Mochkovitch, R.

    2008-05-01

    We compute the expected GRB luminosity function in the internal shock model. We find that if the population of GRB central engines produces all kind of relativistic outflows, from very smooth to highly variable, the luminosity function has to branchs: at low luminosity, the distribution is dominated by low efficiency GRBs and is close to a power law of slope -0.5, whereas at high luminosity, the luminosity function follows the distribution of injected kinetic power. Using Monte Carlo simulations and several observational constrains (BATSE logN-logP diagram, peak energy distribution of bright BATSE bursts, fraction of XRFs in the HETE2 sample), we show that it is currently impossible to distinguish between a single power law or a broken power law luminosity function. However, when the second case is considered, the low-luminosity slope is found to be -0.6+/-0.2, which is compatible with the prediction of the internal shock model.

  16. DETERMINING THE LUMINOSITY FUNCTION OF SWIFT LONG GAMMA-RAY BURSTS WITH PSEUDO-REDSHIFTS

    SciTech Connect

    Tan Weiwei; Yu Yunwei; Cao Xiaofeng

    2013-07-20

    The determination of the luminosity function (LF) of gamma-ray bursts (GRBs) is an important role for the cosmological applications of the GRBs, which, however, is seriously hindered by some selection effects due to redshift measurements. In order to avoid these selection effects, we suggest calculating pseudo-redshifts for Swift GRBs according to the empirical L-E{sub p} relationship. Here, such a L-E{sub p} relationship is determined by reconciling the distributions of pseudo- and real redshifts of redshift-known GRBs. The values of E{sub p} taken from Butler's GRB catalog are estimated with Bayesian statistics rather than observed. Using the GRB sample with pseudo-redshifts of a relatively large number, we fit the redshift-resolved luminosity distributions of the GRBs with a broken-power-law LF. The fitting results suggest that the LF could evolve with redshift by a redshift-dependent break luminosity, e.g., L{sub b} = 1.2 Multiplication-Sign 10{sup 51}(1 + z){sup 2} erg s{sup -1}. The low- and high-luminosity indices are constrained to 0.8 and 2.0, respectively. It is found that the proportional coefficient between the GRB event rate and the star formation rate should correspondingly decrease with increasing redshifts.

  17. The luminosity function of nearby thick-disk sub-dwarfs

    NASA Astrophysics Data System (ADS)

    Arifyanto, M. I.

    2008-07-01

    We derived the luminosity function of thick disk using V/Vmax method for nearby sub-dwarf stars based on the sample stars of Carney et al. (1994). Hipparcos parallaxes and proper motions and Tycho2 proper motions were combined with radial velocities and metallicities from CLLA. We found that the luminosity function in the absolute magnitude range MV = 4 6 mag agree well with the luminosity function derived from the initial mass function (Reyle & Robin 2001).

  18. The cosmological evolution and luminosity function of X-ray selected active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Maccacaro, T.; Gioia, I. M.; Avni, Y.; Giommi, P.; Griffiths, R. E.; Liebert, J.; Stocke, J.; Danziger, J.

    1983-01-01

    The cosmological evolution and the X-ray luminosity function of X-ray selected active galactic nuclei (AGNs) are derived and discussed. The sample used consists of 31 AGNs extracted from a fully identified sample of X-ray sources from the Einstein Observatory Medium Sensitivity Survey and is therefore exclusively defined by its X-ray properties. The distribution in space is found to be strongly nonuniform. The amount of cosmological evolution required by the X-ray data is derived in the framework of pure luminosity evolution and is found to be smaller than the amount determined from optically selected samples. The X-ray luminosity function is derived. It can be satisfactorily represented by a single power law only over a limited range of absolute luminosities. Evidence that the luminosity function flattens at low luminosity or steepens at high luminosity, or both, is presented and discussed.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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 \

  1. SDSS DR4: Progress on the Hot Wire Dwarf Luminosity Function

    DTIC Science & Technology

    2009-01-01

    SDSS DR4: Progress on the hot white dwarf luminosity function This article has been downloaded from IOPscience. Please scroll down to see the full...TITLE AND SUBTITLE SDSS DR4: progress on the hot white dwarf luminosity function 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...Sloan Digital Sky Survey ( SDSS ) data release 4 (DR4) WD catalog data allowed us to obtain a luminosity function (LF)for the hottest WDs. The LF was

  2. The luminosity function for the CfA redshift survey slices

    NASA Technical Reports Server (NTRS)

    De Lapparent, Valerie; Geller, Margaret J.; Huchra, John P.

    1989-01-01

    The luminosity function for two complete slices of the extension of the CfA redshift survey is calculated. The nonparametric technique of Lynden-Bell (1971) and Turner (1979) is used to determine the shape for the luminosity function of the 12 deg slice of the redshift survey. The amplitude of the luminosity function is determined, taking large-scale inhomogeneities into account. The effects of the Malmquist bias on a magnitude-limited redshift survey are examined, showing that the random errors in the magnitudes for the 12 deg slice affect both the determination of the luminosity function and the spatial density constrast of large scale structures.

  3. The VIMOS VLT deep survey. The ultraviolet galaxy luminosity function and luminosity density at 3 ≤ z ≤ 4

    NASA Astrophysics Data System (ADS)

    Paltani, S.; Le Fèvre, O.; Ilbert, O.; Arnouts, S.; Bardelli, S.; Tresse, L.; Zamorani, G.; Zucca, E.; Bottini, D.; Garilli, B.; Le Brun, V.; Maccagni, D.; Picat, J.-P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Bondi, M.; Bongiorno, A.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Lamareille, F.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-03-01

    Aims:We study the luminosity function of the high-redshift galaxy population with redshifts 3≤ z ≤ 4 using a purely I-band magnitude-selected spectroscopic sample obtained in the framework of the VIMOS VLT Deep Survey (VVDS). Methods: We determine the luminosity function from the VVDS, taking care to add as few assumptions and as simple corrections as possible, and compare our results with those obtained from photometric studies, based on Lyman-break selections or photometric-redshift measurements. Results: We find that in the redshift range 3≤ z ≤ 4, the VVDS luminosity function is parameterized by φ^*=1.24+0.48-0.50×10-3 mag-1 Mpc-3 and M^*=-21.49+0.19-0.19, assuming a slope α=-1.4 consistent with most previous studies. While φ* is comparable to previously found values, M* is significantly brighter by about 0.5 mag at least. Using the conservative slope α=-1.4, we find a luminosity density at 1700 Å L1700(M<-18.5)=2.4×1019 W Mpc-3 and L1700Total=3.1×1019 W Mpc-3, comparable to that estimated in other studies. Conclusions: .The unexpectedly large number of very bright galaxies found in the VVDS indicates that the color-selection and photometric-redshift techniques that are generally used to build high-redshift galaxy samples may be affected by a significant fraction of color-measurement failures or by incomplete modelling of the mix of stellar emission, AGN contribution, dust absorption and intergalactic extinction assumed to identify high-redshift galaxies, making pure magnitude selection better able to trace the full population. Because of the difficulty to identify all low-luminosity galaxies in a spectroscopic survey, the luminosity density could still be significantly underestimated. We also find that the relative contribution of the most luminous galaxies compared to the fainter ones is at least twice as large in the VVDS compared to former estimates. Therefore, the VVDS paints a quite different picture of the role of the most actively star

  4. Modeling the luminosity function of galactic low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Kuranov, A. G.; Postnov, K. A.; Revnivtsev, M. G.

    2014-01-01

    The evolution of the family of binaries with a low-mass star and a compact neutron star companion (low-mass X-ray binaries (LMXBs) with neutron stars) ismodeled by the method of population synthesis. Continuous Roche-lobe filling by the optical star in LMXBs is assumed to be maintained by the removal of orbital angular momentum from the binary by a magnetic stellar wind from the optical star and the radiation of gravitational waves by the binary. The developed model of LMXB evolution has the following significant distinctions: (1) allowance for the effect of the rotational evolution of a magnetized compact remnant on themass transfer scenario in the binary, (2) amore accurate allowance for the response of the donor star to mass loss at the Roche-lobe filling stage. The results of theoretical calculations are shown to be in good agreement with the observed orbital period-X-ray luminosity diagrams for persistent Galactic LMXBs and their X-ray luminosity function. This suggests that the main elements of binary evolution, on the whole, are correctly reflected in the developed code. It is shown that most of the Galactic bulge LMXBs at luminosities L x > 1037 erg s-1 should have a post-main-sequence Roche-lobe-filling secondary component (low-mass giants). Almost all of the models considered predict a deficit of LMXBs at X-ray luminosities near ˜1036.5 erg s-1 due to the transition of the binary from the regime of angular momentum removal by a magnetic stellar wind to the regime of gravitational waves (analogous to the widely known period gap in cataclysmic variables, accreting white dwarfs). At low luminosities, the shape of the model luminosity function for LMXBs is affected significantly by their transient behavior-the accretion rate onto the compact companion is not always equal to the mass transfer rate due to instabilities in the accretion disk around the compact object. The best agreement with observed binaries is achieved in the models suggesting that heavy

  5. The Herschel ATLAS: Evolution of the 250 Micrometer Luminosity Function Out to z = 0.5

    NASA Technical Reports Server (NTRS)

    Dye, S.; Dunne, L.; Eales, S.; Smith, D. J. B.; Amblard, A.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A. W.; Bonfield, D. G.; Bremer, M.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D. L.; Cooray, A.; Croom, S.; Dariush, A.; de Zotti, G.; Driver, S.; Dunlop, J. S.; Frayer, D.; Leeuw, L.

    2010-01-01

    We have determined the luminosity function of 250 micrometer-selected galaxies detected in the approximately equal to 14 deg(sup 2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 micrometer luminosity density out to z = 0.2 where it is 3.6(sup +1.4) (sub -0.9) times higher than the local value.

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

    SciTech Connect

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

    2009-05-15

    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. For cluster galaxies, these correspond to L {sub 1.4} = 1.7 x 10{sup 20} W Hz{sup -1}(for a 5{sigma} source) and M{sub r} = -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 10{sup 21} and 10{sup 22} W Hz{sup -1}, an interesting result given star formation dominates field radio luminosity functions for all luminosities lower than about 10{sup 23} W Hz{sup -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 (M{sub r} {<=} -20.5) make the largest contribution to the radio luminosity function at both the high ({approx}>3x10{sup 22} W Hz{sup -1}) and low ({approx}<10{sup 21} W Hz{sup -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 10{sup 19} W Hz{sup -1}. 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} -14

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

    SciTech Connect

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

    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

  8. X-ray Luminosity Functions of Subgalactic Regions in the Whirlpool Galaxy (M51)

    NASA Astrophysics Data System (ADS)

    Markwardt, Larissa; Lehmer, Bret; Eufrasio, Rafael; Basu-Zych, Antara; Fragos, Tassos; Hornschemeier, Ann E.; Kalogera, Vassiliki; Ptak, Andrew; Tzanavaris, Panayiotis; Zezas, Andreas

    2017-01-01

    We present X-ray luminosity functions (XLFs) of X-ray binary (XRB) populations in subgalactic regions in M51, which were selected to have varying levels of low-mass XRBs (LMXBs) and high-mass XRBs (HMXBs). Previous studies have found that the total X-ray luminosity of a galaxy is correlated with its star formation rate (SFR) and stellar mass (M*) according to the equation Lx = αM* + βSFR, where α and β are scaling constants. This result is based on integrated galaxy-wide X-ray luminosities, SFRs, and stellar masses. Here, our goal is to determine this relationship using XLFs within multiple subregions, selected by specific star-formation rate (SFR/M*), of one galaxy (M51). This selection allows us to decompose contributions from LMXB and HMXB populations separately. From this decomposition, we find similar scaling relations to Lehmer et al. (2010), and also find XLF shapes and normalizations that are consistent with past studies of elliptical galaxies (LMXB XLF) and star-forming active galaxies (HMXB XLF). This suggests that our technique is effective and that the star formation history of M51 does not deviate significantly from the average galaxy in the local Universe.

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

    SciTech Connect

    Ansdell, Megan; Baranec, Christoph; Gaidos, Eric; Mann, Andrew W.; Lépine, Sebastien; James, David; Buccino, Andrea; Mauas, Pablo; Petrucci, Romina; Law, Nicholas M.; Riddle, Reed

    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.

  10. Variations in the accretion rate and luminosity in gravitationally unstable protostellar disks

    NASA Astrophysics Data System (ADS)

    Elbakyan, V. G.; Vorobyov, E. I.; Glebova, G. M.

    2016-10-01

    Self-consistent modeling of a protostar and protostellar disk is carried out for early stages of their evolution. The accretion rate at distances of sevral astronomical units from the protostar is appreciably variable, which is reflected in the protostar's luminosity. The amplitude of the variations in the accretion rate and luminosity grows together with the sampling period, as a consequence of the nature of gravitationally unstable protostellar disks. A comparison of model luminosity variations with those derived from observations of nearby sites of star formation shows that the model variations are appreciably lower than the observed values for sampling periods of less than 10 years, indicating the presence of additional sources of variability on small dynamical distances from the protostar.

  11. Calibrating the Decline Rate - Peak Luminosity Relation for Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Rust, Bert W.; Pruzhinskaya, Maria V.; Thijsse, Barend J.

    2015-08-01

    The correlation between peak luminosity and rate of decline in luminosity for Type I supernovae was first studied by B. W. Rust [Ph.D. thesis, Univ. of Illinois (1974) ORNL-4953] and Yu. P. Pskovskii [Sov. Astron., 21 (1977) 675] in the 1970s. Their work was little-noted until Phillips rediscovered the correlation in 1993 [ApJ, 413 (1993) L105] and attempted to derive a calibration relation using a difference quotient approximation Δm15(B) to the decline rate after peak luminosity Mmax(B). Numerical differentiation of data containing measuring errors is a notoriously unstable calculation, but Δm15(B) remains the parameter of choice for most calibration methods developed since 1993. To succeed, it should be computed from good functional fits to the lightcurves, but most workers never exhibit their fits. In the few instances where they have, the fits are not very good. Some of the 9 supernovae in the Phillips study required extinction corrections in their estimates of the Mmax(B), and so were not appropriate for establishing a calibration relation. Although the relative uncertainties in his Δm15(B) estimates were comparable to those in his Mmax(B) estimates, he nevertheless used simple linear regression of the latter on the former, rather than major-axis regression (total least squares) which would have been more appropriate.Here we determine some new calibration relations using a sample of nearby "pure" supernovae suggested by M. V. Pruzhinskaya [Astron. Lett., 37 (2011) 663]. Their parent galaxies are all in the NED collection, with good distance estimates obtained by several different methods. We fit each lightcurve with an optimal regression spline obtained by B. J. Thijsse's spline2 [Comp. in Sci. & Eng., 10 (2008) 49]. The fits, which explain more that 99% of the variance in each case, are better than anything heretofore obtained by stretching "template" lightcurves or fitting combinations of standard lightcurves. We use the fits to compute estimates of

  12. MODELING THE REDSHIFT EVOLUTION OF THE NORMAL GALAXY X-RAY LUMINOSITY FUNCTION

    SciTech Connect

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

    2013-03-20

    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 ({approx}10 Gyr). In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z = 0 to {approx}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 and Georgantopoulos, though they significantly underproduce bright early-type and very bright (L{sub x} > 10{sup 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{sup 40} and 10{sup 41} erg s{sup -1}.

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

    NASA Technical Reports Server (NTRS)

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

    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).

  14. Implications of the Observed Ultraluminous X-Ray Source Luminosity Function

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Tennant, Allyn; Soria, Roberto; Yukita, Mihoko

    2012-01-01

    We present the X-ray luminosity function (XLF) of ultraluminous X-ray (ULX) sources with 0.3-10.0 keV luminosities in excess of 10(sup 39) erg/s in a complete sample of nearby galaxies. The XLF shows a break or cut-off at high luminosities that deviates from its pure power law distribution at lower luminosities. The cut-off is at roughly the Eddington luminosity for a 90-140 solar mass accretor. We examine the effects on the observed XLF of sample biases, of small-number statistics (at the high luminosity end) and of measurement uncertainties. We consider the physical implications of the shape and normalization of the XLF. The XLF is also compared and contrasted to results of other recent surveys.

  15. The galaxy luminosity function and the redshift-distance controversy (A Review)

    PubMed Central

    Salpeter, E. E.; Hoffman, G. L.

    1986-01-01

    The mean relation between distance and redshift for galaxies is reviewed as an observational question. The luminosity function for galaxies is an important ingredient and is given explicitly. We discuss various observational selection effects that are important for comparison of the linear and quadratic distance-redshift laws. Several lines of evidence are reviewed, including the distribution of galaxy luminosities in various redshift ranges, the luminosities of brightest galaxies in groups and clusters at various redshifts, and the Tully-Fisher correlation between neutral hydrogen velocity widths and luminosity. All of these strongly favor the linear law over the quadratic. PMID:16593693

  16. The X-ray luminosity functions of Abell clusters from the Einstein Cluster Survey

    NASA Technical Reports Server (NTRS)

    Burg, R.; Giacconi, R.; Forman, W.; Jones, C.

    1994-01-01

    We have derived the present epoch X-ray luminosity function of northern Abell clusters using luminosities from the Einstein Cluster Survey. The sample is sufficiently large that we can determine the luminosity function for each richness class separately with sufficient precision to study and compare the different luminosity functions. We find that, within each richness class, the range of X-ray luminosity is quite large and spans nearly a factor of 25. Characterizing the luminosity function for each richness class with a Schechter function, we find that the characteristic X-ray luminosity, L(sub *), scales with richness class as (L(sub *) varies as N(sub*)(exp gamma), where N(sub *) is the corrected, mean number of galaxies in a richness class, and the best-fitting exponent is gamma = 1.3 +/- 0.4. Finally, our analysis suggests that there is a lower limit to the X-ray luminosity of clusters which is determined by the integrated emission of the cluster member galaxies, and this also scales with richness class. The present sample forms a baseline for testing cosmological evolution of Abell-like clusters when an appropriate high-redshift cluster sample becomes available.

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

    NASA Astrophysics Data System (ADS)

    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| < 1/3), the Farlie-Gumbel-Morgenstern (FGM) copula provides an intuitive and natural way to construct such a bivariate DF. When the linear 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.

  18. The X-ray luminosity function of active galactic nuclei in the redshift interval z=3-5

    NASA Astrophysics Data System (ADS)

    Georgakakis, A.; Aird, J.; Buchner, J.; Salvato, M.; Menzel, M.-L.; Brandt, W. N.; McGreer, I. D.; Dwelly, T.; Mountrichas, G.; Koki, C.; Georgantopoulos, I.; Hsu, L.-T.; Merloni, A.; Liu, Z.; Nandra, K.; Ross, N. P.

    2015-10-01

    We combine deep X-ray survey data from the Chandra observatory and the wide-area/shallow XMM-XXL field to estimate the active galactic nuclei (AGN) X-ray luminosity function in the redshift range z = 3-5. The sample consists of nearly 340 sources with either photometric (212) or spectroscopic (128) redshift in the above range. The combination of deep and shallow survey fields also provides a luminosity baseline of three orders of magnitude, LX(2-10 keV) ≈ 1043-1046 erg s- 1 at z > 3. We follow a Bayesian approach to determine the binned AGN space density and explore their evolution in a model-independent way. Our methodology properly accounts for Poisson errors in the determination of X-ray fluxes and uncertainties in photometric redshift estimates. We demonstrate that the latter is essential for unbiased measurement of space densities. We find that the AGN X-ray luminosity function evolves strongly between the redshift intervals z = 3-4 and z = 4-5. There is also suggestive evidence that the amplitude of this evolution is luminosity dependent. The space density of AGN with LX(2-10 keV) < 1045 erg s- 1 drops by a factor of 5 between the redshift intervals above, while the evolution of brighter AGN appears to be milder. Comparison of our X-ray luminosity function with that of ultraviolet (UV)/optical selected quasi-stellar objects at similar redshifts shows broad agreement at bright luminosities, LX(2-10 keV) > 1045 erg s- 1. At fainter luminosities X-ray surveys measure higher AGN space densities. The faint-end slope of UV/optical luminosity functions, however, is steeper than for X-ray selected AGN. This implies that the Type I AGN fraction increases with decreasing luminosity at z > 3, opposite to trends established at lower redshift. We also assess the significance of AGN in keeping the hydrogen ionized at high redshift. Our X-ray luminosity function yields ionizing photon rate densities that are insufficient to keep the Universe ionized at redshift z > 4. A

  19. Galaxy And Mass Assembly (GAMA): the 325 MHz radio luminosity function of AGN and star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Prescott, Matthew; Mauch, T.; 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.

    2016-03-01

    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 deg2 radio survey conducted with the Giant Metrewave Radio Telescope, with optical imaging and redshifts from the Galaxy And Mass Assembly 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 Φ ∝ (1 + z)k, we find evolution parameters of k = 0.92 ± 0.95 assuming pure density evolution and k = 2.13 ± 1.96 assuming pure luminosity evolution. We find that the Low Excitation Radio Galaxies are the dominant population in space density at lower luminosities. Comparing our 325 MHz observations with radio continuum imaging at 1.4 GHz, we determine separate radio luminosity functions for steep- and flat-spectrum AGN, and show that the beamed population of flat-spectrum sources in our sample can be shifted in number density and luminosity to coincide with the unbeamed population of steep-spectrum sources, as is expected in the orientation-based unification of AGN.

  20. Lyα luminosity functions at redshift z ≈ 4.5

    NASA Astrophysics Data System (ADS)

    Zheng, Zhen-Ya; Finkelstein, Steven L.; Finkelstein, Keely; Tilvi, Vithal; Rhoads, James E.; Malhotra, Sangeeta; Wang, Jun-Xian; Miller, Neal; Hibon, Pascale; Xia, Lifang

    2013-06-01

    We present a spectroscopically confirmed sample of Lyman α emitting galaxies (LAEs) at z ˜ 4.5 in the Extended Chandra Deep Field-South (ECDFS), which we combine with a sample of z ˜ 4.5 LAEs from previous narrow-band surveys from the Large Area Lyman Alpha (LALA) survey to build a unified Lyα luminosity function. We spectroscopically observed 64 candidate LAEs in the ECDFS, confirming 46 objects as z ˜ 4.5 LAEs based on single-line detections with no continuum emission bluewards of the line, resulting in a Lyα confirmation rate of ˜70 per cent. We did not detect significant flux from neither the C IV λ1549 Å emission line nor the He II λ1640 Å emission line in individual LAE spectra. These lines were also undetected in a co-added spectrum, with the co-added line ratio of He II to Lyα constraining the Population III star formation rate (SFR) to be <0.3 per cent of the total SFR and <1.25 per cent of the observed SFR (both at the 2σ level). We combine the optical spectra with deep X-ray and radio images to constrain the AGN fraction in the sample. Only LAE was detected in both the X-ray and radio, while the other objects remained undetected, even when stacked. The Lyα luminosity functions in our two deepest narrow-band filters in the ECDFS differ at greater than 2σ significance, and the product L*Φ* differs by a factor of >3. Similar luminosity function differences have been used to infer evolution in the neutral gas fraction in the intergalactic medium at z > 6, yet here the difference is likely due to cosmic variance, given that the two samples are from adjoining line-of-sight volumes. Combining our new sample of LAEs with those from previous LALA narrow-band surveys at z = 4.5, we obtain one of the best measured Lyα luminosity functions to date, with our sample of over 200 spectroscopically confirmed Lyα galaxies yielding log10(L*) = 42.83 ± 0.06 (erg s-1) and log10(Φ*) = -3.48 ± 0.09 (Mpc-3). We compare our new luminosity function to others

  1. The Truncated Lognormal Distribution as a Luminosity Function for SWIFT-BAT Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Zaninetti, Lorenzo

    2016-11-01

    The determination of the luminosity function (LF) in gamma ray bursts (GRBs) depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here we analyse three cosmologies: the standard cosmology, the plasma cosmology, and the pseudo-Euclidean universe. The LF of the GRBs is firstly modeled by the lognormal distribution and the four broken power law, and secondly by a truncated lognormal distribution. The truncated lognormal distribution fits acceptably the range in luminosity of GRBs as a function of the redshift.

  2. PROBING THE WARM DARK MATTER WITH THE HIGH-z QUASAR LUMINOSITY FUNCTION

    SciTech Connect

    Song, Hyunmi; Lee, Jounghun

    2009-09-20

    In a warm dark matter (WDM) cosmology, the first objects to form at z >= 20 are one-dimensional filaments with mean length on the order of the WDM free-streaming scale. Gao and Theuns recently claimed by using high-resolution hydrodynamic simulations that the eventual collapse of these WDM filaments along their longest axes may seed the supermassive black holes that power high-z quasars. In this picture, it is supposed that the high-z quasar luminosity function should reflect how abundant the WDM filaments are in the early universe. We derive analytically the mass function of early-universe filaments with the help of the Zel'dovich approximation. Then, we determine the rate of its decrease in the mass section corresponding to the free-streaming scale of a WDM particle of mass m {sub n}u. Adjusting the value of m{sub n}u, we fit the slope of the analytic model to that of the high-z quasar luminosity function measured from the Sloan Digital Sky Survey DR3. A new WDM constraint from this feasibility study is found to be consistent with the lightest super-symmetric partner.

  3. The luminosity functions of the 1969 Perseid and Orionid meteor showers

    NASA Technical Reports Server (NTRS)

    Krisciunas, K.

    1980-01-01

    Observations of the 1969 Perseid and Orionid meteor showers are presented and used to derive luminosity functions for the 288 Perseids and 56 Orionids detected. Visual counts were performed under very good to excellent seeing conditions at the times of peak activities, and the brightnesses of the meteors were estimated to the nearest magnitude by comparison with the magnitudes of known objects. Maximum likelihood estimates of the power law index of the luminosity function of 1.56 + or - 0.06 for the Perseids and of 1.85 + or - 0.1 for the Orionids are obtained which are lower than the values found by other investigators. Under the assumption that the luminosity of visual meteors is proportional to their mass, the luminosity function power law may also be used to characterize the mass function.

  4. Consistency between the luminosity function of resolved millisecond pulsars and the galactic center excess

    NASA Astrophysics Data System (ADS)

    Ploeg, Harrison; Gordon, Chris; Crocker, Roland; Macias, Oscar

    2017-08-01

    Fermi Large Area Telescope data reveal an excess of GeV gamma rays from the direction of the Galactic Center and bulge. Several explanations have been proposed for this excess including an unresolved population of millisecond pulsars (MSPs) and self-annihilating dark matter. It has been claimed that a key discriminant for or against the MSP explanation can be extracted from the properties of the luminosity function describing this source population. Specifically, is the luminosity function of the putative MSPs in the Galactic Center consistent with that characterizing the resolved MSPs in the Galactic disk? To investigate this we have used a Bayesian Markov Chain Monte Carlo to evaluate the posterior distribution of the parameters of the MSP luminosity function describing both resolved MSPs and the Galactic Center excess. At variance with some other claims, our analysis reveals that, within current uncertainties, both data sets can be well fit with the same luminosity function.

  5. The Effect of Variability on X-Ray Binary Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Binder, Breanna A.; Gross, Jacob; Williams, Benjamin F.; Eracleous, Michael; Gaetz, Terrance J.; Plucinsky, Paul P.; Skillman, Evan D.

    2017-08-01

    X-ray binaries are inherently variable X-ray sources, particularly at low luminosities (<1036 erg s-1). Despite this intrinsic variability, the resulting X-ray luminosity functions of X-ray binary populations in star-forming galaxies are remarkably stable across galaxies and across multiple epochs in time. We have obtained three epochs of Chandra ACIS-I observations (totaling ~184 ks) of the nearby spiral galaxy NGC 300 to study the logN-logS distributions of its X-ray point-source population down to 0.35-8 keV luminosities of ~1036 erg s-1. The individual epoch differential logN-logS distributions are best described as the sum of a component made up of background active galactic nuclei (AGN), a simple power law, and a broken power law.We find the shape of the logN-logS distributions sometimes varies between observations. The simple power law and AGN components produce a good fit for “persistent” sources (i.e., with fluxes that remain constant within a factor of ~2). The power-law index of ~1.2 and high fluxes suggest that the persistent sources intrinsic to NGC 300 are dominated by Roche-lobe-overflowing low-mass X-ray binaries. The variable X-ray sources are described by a broken power law, with a faint-end power-law index of ~1.7, a bright-end index of ~2.8-4.9, and a break luminosity of ~4 × 1036 erg s-1. This suggests that these variable sources are mostly outbursting, wind-fed high-mass X-ray binaries, although the logN-logS distribution of variable sources likely also contains low-mass X-ray binaries. We generate model logN-logS distributions for synthetic X-ray binaries and constrain the distribution of maximum X-ray fluxes attained during outburst. Our observations suggest that the majority of X-ray binaries outburst at sub-Eddington luminosities, where mass transfer likely occurs through direct wind accretion at ~1%-3% of the Eddington rate.

  6. VizieR Online Data Catalog: VIPERS: galaxy colours and luminosity function (Fritz+, 2014)

    NASA Astrophysics Data System (ADS)

    Fritz, A.; Scodeggio, M.; Ilbert, O.; Bolzonella, M.; Davidzon, I.; Coupon, J.; Garilli, B.; Guzzo, L.; Zamorani, G.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bottini, D.; Branchini, E.; Cappi, A.; Cucciati, O.; de Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Granett, B. R.; Iovino, A.; Krywult, J.; Le Brun, V.; Le Fevre, O.; Maccagni, D.; Malek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.

    2014-11-01

    Completeness numbers, redshifts, colour intercept evolution, dispersion, Schechter parameters and number densities of the luminosity function are presented for ~45000 galaxies between 0.4luminosity function are presented for the sub-samples of Red and Red-SED galaxies. Completeness numbers are given for both the parent photometric sample and the spectroscopic VIPERS sample. (3 data files).

  7. The level of agreement between theoretical and observed globular cluster luminosity functions.

    NASA Astrophysics Data System (ADS)

    degl'Innocenti, S.; Weiss, A.; Leone, L.

    1997-03-01

    Luminosity functions from theoretical stellar evolution calculations are compared with observed ones of several galactic globular clusters (M 30, M 92, M 68, NGC 6397, M 4, M 80, NGC 6352, NGC 1851). Contrary to earlier results of Faulkner & Swenson (1993ApJ...411..200F) and Bolte (1994ApJ...431..223B) we find no significant discrepancy that could indicate the neglect of important physical effects in the models. However, it is confirmed that the subgiant branch is the most sensitive part and shows the largest deviations in the luminosity function comparison, if parameters are inappropriate. We also find that the main sequence is suited less than the Red Giant Branch for the calibration of theoretical luminosity functions, mainly because of apparent completeness problems. While for individual clusters different changes in the model assumptions might resolve mismatches, there is no systematic trend visible. It rather appears that the quality of the luminosity function in the subgiant part is insufficient and that improved observations of this particular region are necessary for a better comparison. At the present quality of luminosity functions theory is in agreement with observations and a postulation of WIMPs acting in stellar cores does not seem to be justified. However, we conclude that improved data for the main sequence and subgiant branch are clearly needed to exploit the potential of luminosity functions as a diagnostic means for stellar evolution theory.

  8. The faintest stars - The luminosity and mass functions at the bottom of the main sequence

    NASA Technical Reports Server (NTRS)

    Tinney, Christopher G.

    1993-01-01

    We present IR K-band photometry of complete samples of VLM candidates constructed from IIIaF and IVN plates in 10 fields taken as part of the POSSII and UKSRC surveys. Using the I-K colors constructed for these stars we estimate a bolometric luminosity function which extends to M(Bol) = 13.75. We find significant evidence for a luminosity function decreasing toward these luminosities. We also find that our results are consistent with those of studies based on the Nearby Star sample, when those data are presented as a bolometric luminosity function. We convert our observed luminosity function into a mass function, which extends with reasonable statistics to 0.08 solar masses - the H-burning minimum mass. We find significant evidence for features in the mass function at these masses. Specifically, the mass function 'turns over' at 0.25 solar mass, goes through a local minimum at about 0.15 solar mass, and may increase again below 0.1 solar mass - none of these features are predicted by any of the current theories of star formation. Lastly, the mass density we observe just above the H-burning minimum mass makes it difficult to envisage brown dwarfs contributing significant quantities of missing mass without invoking either a mass function in this region significantly steeper than that seen for main-sequence stars, or an extremely low cutoff mass to the mass function.

  9. Effects of Formation Epoch Distribution on X-Ray Luminosity and Temperature Functions of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Enoki, Motohiro; Takahara, Fumio; Fujita, Yutaka

    2001-07-01

    We investigate statistical properties of galaxy clusters in the context of a hierarchical clustering scenario, taking into account their formation epoch distribution; this study is motivated by the recent finding by Fujita and Takahara that X-ray clusters form a fundamental plane in which the mass and the formation epoch are regarded as two independent parameters. Using the formalism that discriminates between major mergers and accretion, the epoch of a cluster formation is identified with that of the last major merger. Since tiny mass accretion following formation does not much affect the core structure of clusters, the properties of X-ray emission from clusters are determined by the total mass and density at their formation time. Under these assumptions, we calculate X-ray luminosity and temperature functions of galaxy clusters. We find that the behavior of the luminosity function differs from the model that does not take into account formation epoch distribution; the behavior of the temperature function, however, is not much different. In our model, the luminosity function is shifted to a higher luminosity and shows no significant evolution up to z~1, independent of cosmological models. The clusters are populated on the temperature-luminosity plane, with a finite dispersion. Since the simple scaling model in which the gas temperature is equal to the virial temperature fails to reproduce the observed luminosity-temperature relation, we also consider a model that takes into account the effects of preheating. The preheating model reproduces the observations much more accurately.

  10. Evolution of the u-band luminosity function from redshift 1.2 to 0

    NASA Astrophysics Data System (ADS)

    Prescott, Matthew; Baldry, Ivan K.; James, Phil A.

    2009-07-01

    We produce and analyse u-band (λ ~ 355 nm) luminosity functions (LFs) for the red and blue populations of galaxies using data from the Sloan Digital Sky Survey (SDSS) u-band Galaxy Survey (uGS) and Deep Evolutionary Exploratory Probe 2 (DEEP2) survey. From a spectroscopic sample of 41575 SDSS uGS galaxies and 24561 DEEP2 galaxies, we produce colour magnitude diagrams and make use of the colour bimodality of galaxies to separate red and blue populations. LFs for eight redshift slices in the range 0.01 < z < 1.2 are determined using the 1/Vmax method and fitted with Schechter functions showing that there is significant evolution in M*, with a brightening of 1.4 mag for the combined population. The integration of the Schechter functions yields the evolution in the u-band luminosity density (LD) out to z ~ 1. By parametrizing the evolution as ρ ~ (1 + z)β, we find that β = 1.36 +/- 0.2 for the combined populations and β = 2.09 +/- 0.2 for the blue population. By removing the contribution of the old stellar population to the u-band LD and correcting for dust attenuation, we estimate the evolution in the star formation rate (SFR) of the Universe to be βSFR = 2.5 +/- 0.3. Discrepancies between our result and higher evolution rates measured using the infrared and far-UV can be reconciled by considering possibilities such as an underestimated dust correction at high redshifts or evolution in the stellar initial mass function.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. The GRB luminosity function: predictions from the internal shock model and comparison with observations

    NASA Astrophysics Data System (ADS)

    Zitouni, H.; Daigne, F.; Mochkovich, R.; Zerguini, T. H.

    2008-05-01

    We compute the expected luminosity function of gamma-ray bursts (GRBs) in the context of the internal shock model. We assume that GRB central engines generate relativistic outflows characterized by the respective distributions of injected kinetic power and contrast in Lorentz factor κ = Γmax/Γmin. We find that if the distribution of contrast extends down to values close to unity (i.e. if both highly variable and smooth outflows can exist), then the luminosity function has two branches. At high luminosity it follows the distribution of while at low luminosity it is close to a power law of slope -0.5. We then examine if existing data can constrain the luminosity function. Using the logN-logP curve, the Ep distribution of bright Burst and Transient Source Experiment (BATSE) bursts and the X-ray flash (XRF)/GRB ratio obtained by High Energy Transient Explorer 2 (HETE2), we show that single and broken power laws can provide equally good fits of these data. Present observations are therefore unable to favour one form or the other. However, when a broken power law is adopted they clearly indicate a low-luminosity slope ~= -0.6 +/- 0.2, compatible with the prediction of the internal shock model.

  13. Luminosity functions and color-magnitude diagrams for three OB associations in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Degioia-Eastwood, K.; Meyers, R. P.; Jones, D. P.

    1993-01-01

    Using the point spread function photometry program DAOPHOT, we have used UBV CCD photometry to construct color-magnitude diagrams and luminosity functions for three OB associations in the Large Magellanic Cloud. The region LH 76 appears to be completely coeval; the region LH 13 shows some evidence for noncoevality which will need to be checked with spectra of the stars in question. The region LH 105, which lies on the southern edge of 30 Doradus, shows significant contamination by an underlying older population, possibly from previous star forming events. The luminosity functions, which serve as the first step toward determining the initial mass function in these regions, are calculated.

  14. Cosmic reionization on computers: The faint end of the galaxy luminosity function

    DOE PAGES

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions atmore » $$z\\gtrsim 6$$. 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. Here, an analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.« less

  15. Cosmic reionization on computers: The faint end of the galaxy luminosity function

    SciTech Connect

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at $z\\gtrsim 6$. 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. Here, an analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.

  16. Cosmic reionization on computers: The faint end of the galaxy luminosity function

    SciTech Connect

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at $z\\gtrsim 6$. 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. Here, an analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.

  17. Cosmic Reionization on Computers: The Faint End of the Galaxy Luminosity Function

    NASA Astrophysics Data System (ADS)

    Gnedin, Nickolay Y.

    2016-07-01

    Using numerical cosmological simulations completed under the “Cosmic Reionization On Computers” project, I explore theoretical predictions for the faint end of the galaxy UV luminosity functions at z≳ 6. A commonly used Schechter function approximation with the magnitude cut at {M}{{cut}}˜ -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}{{cut}} is found to vary between -12 and -14 with a mild redshift dependence. An analytical model of reionization from Madau et al., as used by Robertson et al., provides a good description of the simulated results, which can be improved even further by adding two physically motivated modifications to the original Madau et al. equation.

  18. Introducing the FirstLight project: UV luminosity function and scaling relations of primeval galaxies

    NASA Astrophysics Data System (ADS)

    Ceverino, Daniel; Glover, Simon C. O.; Klessen, Ralf S.

    2017-09-01

    We introduce the FirstLight project, which aims to generate a large data base of high-resolution, zoom-in simulations of galaxy formation around the epoch of reionization (z ≥ 6). The first results of this programme agree well with recent observational constraints at z = 6-8, including the ultraviolet (UV) luminosity function and galaxy stellar mass function, as well as the scaling relationships between halo mass, stellar mass and UV magnitude. The UV luminosity function starts to flatten below MUV > -14 due to stellar feedback in haloes with maximum circular velocities of V = 30-40 km s-1. The power-law slope of the luminosity function evolves rapidly with redshift, reaching a value of α ≃ -2.5 at z = 10. On the other hand, the galaxy stellar mass function evolves slowly with time between z = 8 and 10, in particular, at the low-mass end.

  19. The faint end of the 250 μm luminosity function at z < 0.5

    NASA Astrophysics Data System (ADS)

    Wang, L.; Norberg, P.; 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.

    2016-08-01

    Aims: We aim to study the 250 μm luminosity function (LF) down to much fainter luminosities than achieved by previous efforts. Methods: We developed a modified stacking method to reconstruct the 250 μm 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 μm 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 (~ 25 times fainter) than achieved by previous studies. We find strong positive luminosity evolution L*250(z)∝(1+z)4.89±1.07 and moderate negative density evolution Φ*250(z)∝(1+z)-1.02±0.54 over the redshift range 0.02

  20. Hard X-ray luminosity function of tidal disruption events: First results from the MAXI extragalactic survey

    NASA Astrophysics Data System (ADS)

    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.

  1. VizieR Online Data Catalog: Evolution of quasar luminosity function (Hawkins+ 1995)

    NASA Astrophysics Data System (ADS)

    Hawkins, M. R. S.; Veron, P.

    1997-02-01

    In an earlier paper (Hawkins & Veron, 1993MNRAS.260..202H) we presented quasar luminosity functions in three redshift bins, derived from a variability selected sample. Here we provide a major extension to this survey, with a view to improving statistics and completeness, and extending the redshift range. The luminosity functions for redshifts of less than 2.2 show a featureless power law of the form φ=10β(M-M0), with no sign of a 'break'. The quasar luminosity function is also derived by the redshift range 2.2luminosity functions in all four redshift ranges are consistent with a single power law of index β=0.63. Plots of quasar space density as a function of redshift in three luminosity bins are also presented and show strong evolution at low redshift but nearly constant space density beyond a redshift of 2. (3 data files).

  2. Kinematics of nearby subdwarfs and the luminosity function of the Galactic thick disk

    NASA Astrophysics Data System (ADS)

    Arifyanto, Mochamad Ikbal

    2005-12-01

    We present an analysis of the space motions of 740 subdwarf stars based on the sample stars of Carney et al. (1994; CLLA). Hipparcos parallaxes and proper motion and Tycho2 proper motions were combined with radial velocities and metallicities from CLLA. The kinematical behavior is discussed in particular in relation to their metallicities. For stars with metallicity -1.0<[Fe/H]<-0.4, the velocity distribution represent the thick disk population. We derived the luminosity function of thick disk using 1/Vmax method. We found that the luminosity function in absolute magnitude of MV = 4 - 5 mag, agree well with the Luminosity function derived from the stellar initial function (Reyle & Robin 2001). We analayzed the kinematics in our thick disk sample and found substructure in the thick disk population.

  3. Properties of galaxies at the faint end of the Hα luminosity function at z ~ 0.62

    NASA Astrophysics Data System (ADS)

    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 < z < 0.8 in Hα-based studies. Aims: Our main goal is to study the properties of a sample of faint Hα emitters at z ~ 0.62. We focus on their contribution to the faint end of the luminosity function and derived star formation rate density, characterising their morphologies and basic photometric and spectroscopic properties. Methods: We use a narrow-band technique in the near-infrared, with a filter centred at 1.06 μm. 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. In addition to our survey, we mainly make use of ancillary data coming from the CANDELS and Rainbow Cosmological Surveys Database, from the 3D-HST for comparison, and also spectra from the literature. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. In order to obtain the luminosity function, we apply a traditional V/Vmax method and perform individual extinction corrections for each object to accurately trace the shape of the function. Results: Our 28 Hα-selected sample of faint star-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

  4. The nearby Abell clusters. III. Luminosity functions for eight rich clusters

    SciTech Connect

    Oegerle, W.R.; Hoessel, J.G. Washburn Observatory, Madison, WI )

    1989-11-01

    Red photographic data on eight rich Abell clusters are combined with previous results on four other Abell clusters to study the luminosity functions of the clusters. The results produce a mean value of the characteristic galaxy magnitude (M asterisk) that is consistent with previous results. No relation is found between the magnitude of the first-ranked cluster galaxy and M asterisk, suggesting that the value of M asterisk is not changed by dynamical evolution. The faint ends of the luminosity functions for many of the clusters are quite flat, validating the nonuniversality in the parametrization of Schechter (1976) functions for rich clusters of galaxies. 40 refs.

  5. The nearby Abell clusters. III - Luminosity functions for eight rich clusters

    NASA Technical Reports Server (NTRS)

    Oegerle, William R.; Hoessel, John G.

    1989-01-01

    Red photographic data on eight rich Abell clusters are combined with previous results on four other Abell clusters to study the luminosity functions of the clusters. The results produce a mean value of the characteristic galaxy magnitude (M asterisk) that is consistent with previous results. No relation is found between the magnitude of the first-ranked cluster galaxy and M asterisk, suggesting that the value of M asterisk is not changed by dynamical evolution. The faint ends of the luminosity functions for many of the clusters are quite flat, validating the nonuniversality in the parametrization of Schechter (1976) functions for rich clusters of galaxies.

  6. A physical model for the evolving ultraviolet luminosity function of high redshift galaxies and their contribution to the cosmic reionization

    SciTech Connect

    Cai, Zhen-Yi; Lapi, Andrea; Bressan, Alessandro; De Zotti, Gianfranco; Danese, Luigi; Negrello, Mattia

    2014-04-10

    We present a physical model for the evolution of the ultraviolet (UV) luminosity function of high-redshift galaxies, taking into account in a self-consistent way their chemical evolution and the associated evolution of dust extinction. Dust extinction is found to increase fast with halo mass. A strong correlation between dust attenuation and halo/stellar mass for UV selected high-z galaxies is thus predicted. The model yields good fits of the UV and Lyman-α (Lyα) line luminosity functions at all redshifts at which they have been measured. The weak observed evolution of both luminosity functions between z = 2 and z = 6 is explained as the combined effect of the negative evolution of the halo mass function; of the increase with redshift of the star formation efficiency due to the faster gas cooling; and of dust extinction, differential with halo mass. The slope of the faint end of the UV luminosity function is found to steepen with increasing redshift, implying that low luminosity galaxies increasingly dominate the contribution to the UV background at higher and higher redshifts. The observed range of the UV luminosities at high z implies a minimum halo mass capable of hosting active star formation M {sub crit} ≲ 10{sup 9.8} M {sub ☉}, which is consistent with the constraints from hydrodynamical simulations. From fits of Lyα line luminosity functions, plus data on the luminosity dependence of extinction, and from the measured ratios of non-ionizing UV to Lyman-continuum flux density for samples of z ≅ 3 Lyman break galaxies and Lyα emitters, we derive a simple relationship between the escape fraction of ionizing photons and the star formation rate. It implies that the escape fraction is larger for low-mass galaxies, which are almost dust-free and have lower gas column densities. Galaxies already represented in the UV luminosity function (M {sub UV} ≲ –18) can keep the universe fully ionized up to z ≅ 6. This is consistent with (uncertain) data

  7. A Luminosity Function of Lyα-emitting Galaxies at z ~ 4.5

    NASA Astrophysics Data System (ADS)

    Dawson, Steve; Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Wang, JunXian; Dey, Arjun; Spinrad, Hyron; Jannuzi, Buell T.

    2007-12-01

    We present a catalog of 59 z~4.5 Lyα-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Area Lyα (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 ~76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z~4.5 Lyα-emitting galaxies in the ~0.7 deg2 covered by the LALA imaging. As with the Keck LRIS sample, we find that a nonnegligible fraction of the confirmed Lyα lines have rest-frame equivalent widths (Wrestλ) that exceed the maximum predicted for normal stellar populations: 17%-31% (93% confidence) of the detected galaxies show Wrestλ>190 Å, and 12%-27% (90% confidence) show Wrestλ>240 Å. We construct a luminosity function of z~4.5 Lyα emission lines for comparison to Lyα luminosity functions spanning 3.1luminosity function evolution from z~3 to z~6. This result supports the conclusion that the intergalactic medium remains largely reionized from the local universe out to z~6.5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z~3 and z~6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations. Based in part on observations made at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Our data were obtained using community access telescope time made available under the National

  8. X-ray luminosity functions of different morphological and X-ray type AGN populations

    NASA Astrophysics Data System (ADS)

    Pović, M.; Pérez García, A. M.; Sánchez-Portal, M.; Bongiovanni, A.; Cepa, J.; Fernández Lorenzo, M.; Lara-López, M. A.; Gallego, J.; Ederoclite, A.; Márquez, I.; Masegosa, J.; Alfaro, E.; Castañeda, H.; González-Serrano, J. I.; González, J. J.

    2013-03-01

    Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray luminosity functions for X-ray detected AGN in the SXDS and GWS fields. The limiting fluxes of our samples are 9.0 ×10-15 and 4.8 ×10-16 erg cm-2 s-1 in the 0.5-7.0 keV band in the two fields, respectively. We carried out analysis in three X-ray bands and in two redshift intervals up to z≤1.4. Moreover, we derive the luminosity functions for different optical morphologies and X-ray types. We confirm strong luminosity evolution in all three bands, finding the most luminous objects at higher redshift. However, no signs of density evolution are found in any tested X-ray band. We obtain similar results for compact and early-type objects. Finally, we observe the ``Steffen effect'', where X-ray type-1 sources are more numerous at higher luminosities in comparison with type-2 sources.

  9. Fossil group origins. V. The dependence of the luminosity function on the magnitude gap

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Barrena, R.; Boschin, W.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Girardi, M.; Iglesias-Páramo, J.; Kundert, A.; Méndez-Abreu, J.; Vilchez, J. M.

    2015-09-01

    Context. In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (Δm12). Thus, there are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. The observed distribution of magnitude gaps is thought to be a consequence of the orbital decay of M∗ galaxies in massive halos and the associated growth of the central object. As a result, to first order the amplitude of this gap is a good statistical proxy for the dynamical age of a system of galaxies. Fossil and non-fossil systems could therefore have different galaxy populations that should be reflected in their luminosity functions. Aims: In this work we study, for the first time, the dependence of the luminosity function parameters on Δm12 using data obtained by the fossil group origins (FOGO) project. Methods: We constructed a hybrid luminosity function for 102 groups and clusters at z ≤ 0.25 using both photometric data from the SDSS-DR7 and redshifts from the DR7 and the FOGO surveys. The latter consists of ~1200 new redshifts in 34 fossil system candidates. We stacked all the individual luminosity functions, dividing them into bins of Δm12, and studied their best-fit Schechter parameters. We additionally computed a "relative" luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differences - especially at the bright end. Results: We find trends as a function of Δm12 at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude M∗. The characteristic luminosity in systems with negligible gaps is more than a factor three brighter than in fossil-like ones. Remarkably, we also find differences at the faint end. In this region, the larger the gap, the flatter

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

    SciTech Connect

    Ross, Nicholas P.; White, Martin; Bailey, Stephen; McGreer, Ian D.; Richards, Gordon T.; Myers, Adam D.; Palanque-Delabrouille, Nathalie; Yeche, Christophe; Strauss, Michael A.; Anderson, Scott F.; Shen, Yue; Swanson, Molly E. C.; Brandt, W. N.; Aubourg, Eric; Bovy, Jo; DeGraf, Colin; Di Matteo, Tiziana; 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.

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

    DOE PAGES

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; ...

    2015-09-18

    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 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excessmore » in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.« less

  12. Luminosity function of [O II] emission-line galaxies in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Di Matteo, Tiziana; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu; Khandai, Nishikanta

    2015-11-01

    We examine the luminosity function (LF) of [O II] 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 ≤ z ≤ 3.0 using the [O II] emission line luminosity L([O II]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [O II] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([O II]) = 1043.0 erg s-1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [O II] galaxies, but still displaying a good match with observations below L([O II]) = 1041.6 erg s-1. Based on the validity in reproducing the properties of [O II] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [O II] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from -3 to -2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)-1 at z ≤ 2 while the faint end evolves as ˜3(z + 1)-1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [O III] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. Finally, we show that the auto-correlation function of [O II] and [O III] emitting galaxies shows a rapid evolution from z = 2 to 1.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Luminosities and mass-loss rates of SMC and LMC AGB stars and red supergiants

    NASA Astrophysics Data System (ADS)

    Groenewegen, M. A. T.; Sloan, G. C.; Soszyński, I.; Petersen, E. A.

    2009-11-01

    Context: Mass loss is one of the fundamental properties of Asymptotic Giant Branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims: To investigate the relation between mass loss, luminosity and pulsation period for a large sample of evolved stars in the Small and Large Magellanic Cloud. Methods: Dust radiative transfer models are presented for 101 carbon stars and 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5-35 μm Spitzer IRS spectra are available. The spectra are complemented with available optical and infrared photometry to construct the spectral energy distribution. A minimisation procedure is used to fit luminosity, mass-loss rate and dust temperature at the inner radius. Different effective temperatures and dust content are also considered. Periods from the literature and from new OGLE-III data are compiled and derived. Results: We derive (dust) mass-loss rates and luminosities for the entire sample. Based on luminosities, periods and amplitudes and colours, the O-rich stars are classified as foreground objects, AGB stars and Red Super Giants. For the O-rich stars silicates based on laboratory optical constants are compared to “astronomical silicates”. Overall, the grain type by Volk & Kwok (1988, ApJ, 331, 435) fits the data best. However, the fit based on laboratory optical constants for the grains can be improved by abandoning the small-particle limit. The influence of grain size, core-mantle grains and porosity are explored. A computationally convenient method that seems to describe the observed properties in the 10 μm window are a distribution of hollow spheres with a large vacuum fraction (typically 70%), and grain size of about 1 μm. Relations between mass-loss rates and luminosity and pulsation

  15. THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Cool, Richard J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Brown, Michael J. I.; Caldwell, Nelson; Forman, William R.; Hickox, Ryan C.; Jones, Christine; Murray, Stephen S.; Dey, Arjun; Jannuzi, Buell T.; Moustakas, John

    2012-03-20

    We present the galaxy optical luminosity function for the redshift range 0.05 < z < 0.75 from the AGN and Galaxy Evolution Survey, a spectroscopic survey of 7.6 deg{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z){sup (0.54{+-}0.64)} for red galaxies and (1 + z){sup (1.64{+-}0.39)} for blue galaxies.

  16. The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Jordán, Andrés; McLaughlin, Dean E.; Côté, Patrick; Ferrarese, Laura; Peng, Eric W.; Mei, Simona; Villegas, Daniela; Merritt, David; Tonry, John L.; West, Michael J.

    2007-07-01

    massive galaxies. We probe the variation of the GCLF to projected galactocentric radii of 20-35 kpc in the Virgo giants M49 and M87, finding that the turnover point is essentially constant over these spatial scales. Our fits of evolved Schechter functions imply average dynamical mass losses (Δ) over a Hubble time that vary more than MTO, and systematically but nonmonotonically as a function of galaxy luminosity. If the initial GC mass distributions rose steeply toward low masses as we assume, then these losses fall in the range 2×105 Msolar<~Δ<106 Msolar per GC for all of our galaxies. The trends in Δ are broadly consistent with observed, small variations of the mean GC half-light radius in ACSVCS galaxies, and with rough estimates of the expected scaling of average evaporation rates (galaxy densities) versus total luminosity. We agree with previous suggestions that if the full GCLF is to be understood in more detail, especially alongside other properties of GC systems, the next generation of GCLF models will have to include self-consistent treatments of dynamical evolution inside time-dependent galaxy potentials. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  17. MIR Luminosity Function of Galaxies in the Nep-Wide Field

    NASA Astrophysics Data System (ADS)

    Kim, Seong Jin; Lee, Hyung Mok; Jeong, Woong-Seob; NEP Team

    2017-03-01

    We present the mid-infrared (MIR) luminosity function (LF) of local (z < 0.3) star-forming (SF) galaxies in the North Ecliptic Pole (NEP) field. This work is based on the NEP-Wide point source catalogue and the spectroscopic redshift (z) data for ∼1700 galaxies obtained by the optical follow-up survey with MMT/Hectospec and WIYN/Hydra. The AKARI's continuous 2-24 μm coverage and the spectroscopic redshifts enable us to determine the spectral energy distribution (SED) in the mid-infrared and derive the luminosity functions of galaxies. Our 8 μm LF finds good agreements with the results from SWIRE field over the wide luminosity range, while showing significant difference from the NOAO deep data in the faint end. The comparison with higher-z sample shows significant luminosity evolution from z > 0.3 to local universe. 12 μm LF also shows a clear indication of luminosity evolution.

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

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2017-01-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of active galactic nuclei (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 illustrated at z≈0 and 0.9 using the limited data that is currently available, and a clear luminosity dependence in the AGN bias and mean halo mass is predicted at both, supporting the idea that there are at least two different modes of AGN triggering. In addition, the CLF predicts that z≈0.9 quasars may be commonly hosted by haloes with Mh ~ 1014 M⊙. These `young cluster' environments may provide the necessary interactions between gas-rich galaxies to fuel luminous accretion. The results derived from this method will be useful to populate AGNs of different luminosities in cosmological simulations.

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

    SciTech Connect

    Muzzin, Adam; Yee, H.K.C.; Hall, Patrick B.; Ellingson, E.; 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

  20. STAR FORMATION RATES FOR STARBURST GALAXIES FROM ULTRAVIOLET, INFRARED, AND RADIO LUMINOSITIES

    SciTech Connect

    Sargsyan, Lusine A.; Weedman, Daniel W. E-mail: dweedman@isc.astro.cornell.edu

    2009-08-20

    We present a comparison of star formation rates (SFR) determined from mid-infrared 7.7 {mu}m polycyclic aromatic hydrocarbon (PAH) luminosity [SFR(PAH)], from 1.4 GHz radio luminosity [SFR(radio)], and from far-ultraviolet luminosity [SFR(UV)] for a sample of 287 starburst galaxies with z < 0.5 having Spitzer IRS observations. The previously adopted relation log [SFR(PAH)] = log [{nu}L {sub {nu}}(7.7 {mu}m)] - 42.57 {+-} 0.2, for SFR in M{sub sun} yr{sup -1} and {nu}L {sub {nu}}(7.7 {mu}m) the luminosity at the peak of the 7.7 {mu}m PAH feature in erg s{sup -1}, is found to agree with SFR(radio). Comparing with SFR(UV) determined independently from ultraviolet observations of the same sources with the Galaxy Evolution Explorer mission (not corrected for dust extinction), the median log [SFR(PAH)/SFR(UV)] = 1.67, indicating that only 2% of the ultraviolet continuum typically escapes extinction by dust within a starburst. This ratio SFR(PAH)/SFR(UV) depends on infrared luminosity, with the form log [SFR(PAH)/SFR(UV)] = (0.53 {+-} 0.05)log [{nu}L{sub {nu}}(7.7 {mu}m)] - 21.5 {+-} 0.18, indicating that more luminous starbursts are also dustier. Using our adopted relation between {nu}L{sub {nu}}(7.7 {mu}m) and L {sub ir}, this becomes log [SFR(PAH)/SFR(UV)]= (0.53 {+-} 0.05)log L{sub ir} - 4.11 {+-} 0.18, for L{sub ir} in L{sub sun}. Only blue compact dwarf galaxies show comparable or greater SFR(UV) compared to SFR(PAH). We also find that the ratio SFR(PAH)/SFR(UV) is similar to that in infrared-selected starbursts for a sample of Markarian starburst galaxies originally selected using optical classification, which implies that there is no significant selection effect in SFR(PAH)/SFR(UV) using starburst galaxies discovered by Spitzer. These results indicate that SFRs determined with ultraviolet luminosities require dust corrections by a factor of {approx}10 for typical local starbursts but this factor increases to >700 for the most luminous starbursts at z {approx} 2

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

    SciTech Connect

    Cui, X. H.; Wu, X. F.; Wei, J. J.; Yuan, F.; Zheng, W. K.; Liang, E. W.; Akerlof, C. W.; McKay, T. A.; Ashley, M. C. B.; Flewelling, H. A.; Göǧüş, E.; Güver, T.; Kızıloǧlu, Ü.; Pandey, S. B.; Rykoff, E. S.; Rujopakarn, W.; Schaefer, B. E.; Wheeler, J. C.; Yost, S. A. E-mail: xfwu@pmo.ac.cn E-mail: fang.yuan@anu.edu.au E-mail: lew@gxu.edu.cn

    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.

  2. A MULTIVARIATE FIT LUMINOSITY FUNCTION AND WORLD MODEL FOR LONG GAMMA-RAY BURSTS

    SciTech Connect

    Shahmoradi, Amir

    2013-04-01

    It is proposed that the luminosity function, the rest-frame spectral correlations, and distributions of cosmological long-duration (Type-II) gamma-ray bursts (LGRBs) may be very well described as a multivariate log-normal distribution. This result is based on careful selection, analysis, and modeling of LGRBs' temporal and spectral variables in the largest catalog of GRBs available to date: 2130 BATSE GRBs, while taking into account the detection threshold and possible selection effects. Constraints on the joint rest-frame distribution of the isotropic peak luminosity (L{sub iso}), total isotropic emission (E{sub iso}), the time-integrated spectral peak energy (E{sub p,z}), and duration (T{sub 90,z}) of LGRBs are derived. The presented analysis provides evidence for a relatively large fraction of LGRBs that have been missed by the BATSE detector with E{sub iso} extending down to {approx}10{sup 49} erg and observed spectral peak energies (E{sub p} ) as low as {approx}5 keV. LGRBs with rest-frame duration T{sub 90,z} {approx}< 1 s or observer-frame duration T{sub 90} {approx}< 2 s appear to be rare events ({approx}< 0.1% chance of occurrence). The model predicts a fairly strong but highly significant correlation ({rho} = 0.58 {+-} 0.04) between E{sub iso} and E{sub p,z} of LGRBs. Also predicted are strong correlations of L{sub iso} and E{sub iso} with T{sub 90,z} and moderate correlation between L{sub iso} and E{sub p,z}. The strength and significance of the correlations found encourage the search for underlying mechanisms, though undermine their capabilities as probes of dark energy's equation of state at high redshifts. The presented analysis favors-but does not necessitate-a cosmic rate for BATSE LGRBs tracing metallicity evolution consistent with a cutoff Z/Z{sub Sun} {approx} 0.2-0.5, assuming no luminosity-redshift evolution.

  3. Detailed Shape and Evolutionary Behavior of the X-Ray Luminosity Function of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Miyaji, T.; Hasinger, G.; 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.

    2015-05-01

    We construct the rest-frame 2-10 keV intrinsic X-ray luminosity function (XLF) 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 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 also been revealed, where the number density curves have two clear breaks at all luminosity classes above log {{L}X}\\gt 43. The two-break structure is suggestive of two-phase AGN evolution, consisting of major merger triggering and secular processes.

  4. The Luminosity Function and Mean Galaxy Density from the ESP Galaxy Redshift Survey

    NASA Astrophysics Data System (ADS)

    Zucca, Elena; 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.

    We summarise the main results obtained over the last two years by the ESO Slice Project (ESP) redshift survey, concerning the luminosity function and mean density of galaxies, and their implications for the galaxy number counts at bright magnitudes. The bj-band luminosity function is characterised by a steep faint-end, which raises above a "global" Schechter fit for M_bj > -17 + 5log(h) and is well described by a power-law with slope ~ -1.6. This steepening is mostly produced by galaxies with emission lines, with a clear trend for galaxies with larger [OII] equivalent widths to show a steeper faint end (and a fainter M*). The normalization of the luminosity function is about a factor of 1.6 higher that that from the Stromlo-APM survey. We find that, in fact, the mean density can be seen to increase out to ~140/h Mpc. If we take this into account when computing the expected cumulative number counts from the observed luminosity function, we are able to reproduce the observed steep counts at bright (bj<17) magnitudes very accurately.

  5. The radio luminosity function of spiral galaxies - Correlations with aggregation and Hubble type

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Trinchieri, G.

    1981-04-01

    The Radio Luminosity Function of spiral galaxies is derived from the Arecibo observations of UGC galaxies at 2380 MHz. It is found that the average radio power and the optical luminosity are linearly correlated (αL1) and that, at any given radio power, the probability for a spiral galaxy to become a radio source scales with the optical luminosity as L1.3. Both results confirm the analysis of Hummel (1980, b) who studied with the Westerbork radio telescope (WSRT) the 1415 MHz continuum emission from nearby spiral galaxies. It is also attempted to correlate the radio emission from spiral galaxies with their detailed Hubble type and cluster membership. A weak evidence is found that early type galaxies and cluster members are slightly deficient in radio emission with respect to late type or isolated galaxies, particularly among the optically brightest objects.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    We describe modifications to the joint stepwise maximum-likelihood method of Cole in order to simultaneously fit the Galaxy and Mass Assembly II galaxy luminosity function (LF), corrected for radial density variations, and its evolution with redshift. The whole sample is reasonably well fitted 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 subsamples, using both Petrosian and Sérsic magnitudes. Petrosian magnitudes miss a substantial fraction of the flux of de Vaucouleurs profile galaxies: the Sérsic LF is substantially higher than the Petrosian LF at the bright end.

  7. The metallicity dependence of the long-duration gamma-ray burst rate from host galaxy luminosities

    NASA Astrophysics Data System (ADS)

    Wolf, Christian; Podsiadlowski, Philipp

    2007-03-01

    We investigate the difference between the host galaxy properties of core-collapse supernovae (CC SNe) and long-duration gamma-ray bursts (LGRBs), and quantify a possible metallicity dependence of the efficiency of producing LGRBs. We use a sample of 16 CC SNe and 16 LGRBs from Fruchter et al. which have similar redshift distributions to eliminate galaxy evolution biases. We make a forward prediction of their host galaxy luminosity distributions from the overall cosmic metallicity distribution of star formation. The latter is based on luminosity functions, star formation rates (SFRs) and luminosity-metallicity (L-Z) relations of galaxies. This approach is supported by the finding that LGRB hosts follow the L-Z relations of star-forming galaxies. We then compare predictions for metallicity-dependent event efficiencies with the observed host data. We find that ultraviolet-based SFR estimates predict the host distribution of CC SNe perfectly well in a metallicity-independent form. In contrast, LGRB hosts are on average fainter by one magnitude, almost as faint as the Large Magellanic Cloud. Assuming this to be a metallicity effect, the present data are insufficient to discriminate between a sharp cut-off and a soft decrease in efficiency towards higher metallicity. For a sharp cut-off, however, we find a best value for the cut-off metallicity, as reflected in the oxygen abundance, 12 + log(O/H)lim ~= 8.7 +/- 0.3 at 95 per cent confidence including systematic uncertainties, in the calibration of Asplund, Grevesse & Sauval. This value is somewhat lower than the traditionally quoted value for the Sun, but is comparable to the revised solar oxygen abundance. LGRB models that require sharp metallicity cut-offs well below approximately one-half the revised solar metallicity appear to be effectively ruled out, as they would require fainter LGRB hosts than those that are observed. We also discuss the likely implications of the still ongoing metallicity `calibration debate'.

  8. The Luminosity Function at z ~ 8 from 97 Y-band Dropouts: Inferences about Reionization

    NASA Astrophysics Data System (ADS)

    Schmidt, Kasper B.; Treu, Tommaso; Trenti, Michele; Bradley, Larry D.; Kelly, Brandon C.; Oesch, Pascal A.; Holwerda, Benne W.; Shull, J. Michael; Stiavelli, Massimo

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ~ 8 Lyman break galaxies, LBGs) based on 350 arcmin2 of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin2 of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ~ 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 <= mJ <= 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ~ 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M^\\star = -20.15^{+0.29}_{-0.38}, a faint-end slope of \\alpha = -1.87^{+0.26}_{-0.26}, and a number density of log _{10} \\phi ^\\star [{Mpc}^{-3}] = -3.24^{+0.25}_{-0.24}. Integrated down to M = -17.7, this luminosity function yields a luminosity density log _{10} \\epsilon [erg\\, s^{-1\\, Hz^{-1}\\, Mpc^{-3}}] = 25.52^{+0.05}_{-0.05}. Our luminosity function analysis is consistent with previously published determinations within 1σ. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of reionization. By assuming theoretically motivated priors on the clumping

  9. Constraints on dark matter scenarios from measurements of the galaxy luminosity function at high redshifts

    NASA Astrophysics Data System (ADS)

    Corasaniti, P. S.; Agarwal, S.; Marsh, D. J. E.; Das, S.

    2017-04-01

    We use state-of-the-art measurements of the galaxy luminosity function (LF) at z =6 , 7, and 8 to derive constraints on warm dark matter (WDM), late-forming dark matter, and ultralight axion dark matter models alternative to the cold dark matter (CDM) paradigm. To this purpose, we have run a suite of high-resolution N -body simulations to accurately characterize the low-mass end of the halo mass function and derive dark matter (DM) model predictions of the high-z luminosity function. In order to convert halo masses into UV magnitudes, we introduce an empirical approach based on halo abundance matching, which allows us to model the LF in terms of the amplitude and scatter of the ensemble average star formation rate halo mass relation, ⟨SFR (Mh ,z )⟩, of each DM model. We find that, independent of the DM scenario, the average SFR at fixed halo mass increases from z =6 to 8, while the scatter remains constant. At halo mass Mh≳1012 M⊙ h-1 , the average SFR as a function of halo mass follows a double power law trend that is common to all models, while differences occur at smaller masses. In particular, we find that models with a suppressed low-mass halo abundance exhibit higher SFR compared to the CDM results. Thus, different DM models predict a different faint-end slope of the LF which causes the goodness of fit to vary within each DM scenario for different model parameters. Using deviance statistics, we obtain a lower limit on the WDM thermal relic particle mass, mWDM≳1.5 keV at 2 σ . In the case of LFDM models, the phase transition redshift parameter is bounded to zt≳8 ×105 at 2 σ . We find ultralight axion dark matter best-fit models with axion mass ma≳1.6 ×10-22 eV to be well within 2 σ of the deviance statistics. We remark that measurements at z =6 slightly favor a flattening of the LF at faint UV magnitudes. This tends to prefer some of the non-CDM models in our simulation suite, although not at a statistically significant level to distinguish

  10. RE-ANALYSIS OF THE RADIO LUMINOSITY FUNCTION OF GALACTIC H II REGIONS

    SciTech Connect

    Paladini, R.; Noriega-Crespo, A.; Carey, S. J.; DeZotti, G.

    2009-09-10

    We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic H II regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and supergiant H II regions, a significant number of subgiant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered H II regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23 {+-} 0.07 (fourth quadrant) and to -1.85 {+-} 0.11 (first quadrant). We also find marginal evidence of a luminosity break at L{sub knee} = 10{sup 23.45} erg s{sup -1} Hz{sup -1} for the LF in the fourth quadrant. We convert radio luminosities into equivalent H{alpha} and Lyman continuum luminosities to facilitate comparisons with extragalactic studies. We obtain an average total H II regions Lyman continuum luminosity of 0.89 {+-} 0.23 x 10{sup 53} s{sup -1}, corresponding to 30% of the total ionizing luminosity of the Galaxy.

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

    NASA Astrophysics Data System (ADS)

    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_<=-12.4+5logh), our data suggest the presence of a steepening of the luminosity function for 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_<=-16+5logh is well determined (n{bar}=0.08+/-0.015h^3^/Mpc^3^). Its estimate for M_bJ_<=-12.4+5logh is more uncertain, ranging from n{bar}=0.28h

  12. Star-formation rates, molecular clouds, and the origin of the far-infrared luminosity of isolated and interacting galaxies

    NASA Technical Reports Server (NTRS)

    Solomon, P. M.; Sage, L. J.

    1988-01-01

    The CO luminosities of 93 galaxies have been determined and are compared with their IRAS FIR luminosities. Strongly interacting/merging galaxies have L(FIR)/L(CO) substantially higher than that of isolated galaxies or galactic giant molecular clouds (GMCs). Galaxies with tidal tails/bridges are the most extreme type with L(FIR)/L(CO) nine times as high as isolated galaxies. Interactions between close pairs of galaxies do not have much effect on the molecular content and global star-formation rate. If the high ratio L(FIR)/L(CO) in strongly interacting galaxies is due to star formation then the efficiency of this process is higher than that of any galactic GMC. Isolated galaxies, distant pairs, and close pairs have an FIR/CO luminosity ratio which is within a factor of two of galactic GMCs with H II regions. The CO luminosities of FIR-luminous galaxies are among the highest observed for any spiral galaxies.

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

    SciTech Connect

    Harris, William E.; O'Halloran, Heather; Cockcroft, Robert E-mail: ohallohm@mcmaster.ca; 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.

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

    NASA Technical Reports Server (NTRS)

    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

  15. The Evolution of the Galaxy Rest-frame Ultraviolet Luminosity Function over the First Two Billion Years

    NASA Astrophysics Data System (ADS)

    Finkelstein, Steven L.; Ryan, Russell E., Jr.; Papovich, Casey; Dickinson, Mark; Song, Mimi; Somerville, Rachel S.; 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.

    2015-09-01

    We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity functions at z = 4-8. We use deep Hubble Space Telescope imaging over the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/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 × 106 Mpc3 over this epoch, allowing us to perform a robust search for faint ({M}{UV}=-18) and bright (M{}{UV}\\lt -21) high-redshift galaxies. We select candidate galaxies using a well-tested photometric redshift technique with careful screening of contaminants, finding a sample of 7446 candidate galaxies at 3.5 \\lt z \\lt 8.5, with >1000 galaxies at z ≈ 6-8. We measure both a stepwise luminosity function for candidate galaxies in our redshift samples, and 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 candidate galaxies at z ≥slant 6. Our best-fit value of the characteristic magnitude {M}{UV}* is consistent with -21 at z ≥slant 5, which is different than that inferred based on previous trends at lower redshift, and brighter at ˜2σ significance than previous measures at z = 6 and 7. 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}{UV}* is consistent with models where the impact of dust attenuation on the bright end of the luminosity function decreases at higher redshift, although a decreasing impact of feedback may also be possible. We measure the evolution of the cosmic star-formation rate (SFR) density by

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

    NASA Technical Reports Server (NTRS)

    Mehta, Vihang; Scarlata, Claudia; Colbert, James W.; Dai, Y. S.; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry I.; hide

    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).

  17. The luminosity function for different morphological types in the CfA Redshift Survey

    NASA Technical Reports Server (NTRS)

    Marzke, Ronald O.; Geller, Margaret J.; Huchra, John P.; Corwin, Harold G., Jr.

    1994-01-01

    We derive the luminosity function for different morphological types in the original CfA Redshift Survey (CfA1) and in the first two slices of the CfA Redshift Survey Extension (CfA2). CfA1 is a complete sample containing 2397 galaxies distributed over 2.7 steradians with m(sub z) less than or equal 14.5. The first two complete slices of CfA2 contain 1862 galaxies distributed over 0.42 steradians with m(sub z)=15.5. The shapes of the E-S0 and spiral luminosity functions (LF) are indistinguishable. We do not confirm the steeply decreasing faint end in the E-S0 luminosity function found by Loveday et al. for an independent sample in the southern hemisphere. We demonstrate that incomplete classification in deep redshift surveys can lead to underestimates of the faint end of the elliptical luminosity function and could be partially responsible for the difference between the CfA survey and other local field surveys. The faint end of the LF for the Magellanic spirals and irregulars is very steep. The Sm-Im luminosity function is well fit by a Schechter function with M*=-18.79, alpha=-1.87, and phi*=0.6x10(exp -3) for M(sub z) less than or equal to -13. These galaxies are largely responsible for the excess at the faint end of the general CfA luminosity function. The abundance of intrinsically faint, blue galaxies nearby affects the interpretation of deep number counts. The dwarf population increases the expected counts at B=25 in a no-evolution, q(sub 0)=0.05 model by a factor of two over standard no-evolution estimates. These dwarfs change the expected median redshift in deep redshift surveys by less than 10 percent . Thus the steep Sm-Im LF may contribute to the reconciliation of deep number counts with deep redshift surveys.

  18. The Main-Sequence Luminosity Function of Palomar 5 from THE HUBBLE SPACE TELESCOPE

    NASA Astrophysics Data System (ADS)

    Grillmair, Carl J.; Smith, Graeme H.

    2001-12-01

    A low mass, large core radius, low central concentration, and strong tidal tails suggest that the globular cluster Palomar 5 has lost a large fraction of its initial mass over time. If the dynamical evolution of Pal 5 has been dominated by the effects of mass loss, then theoretical arguments suggest that the luminosity function should be deficient in low-mass stars. Using deep WFPC2 F555W and F814W photometry, we determine the main-sequence luminosity functions both near the cluster center and in a field near the half-light radius. A comparison of these luminosity functions yields no compelling evidence of mass segregation within the cluster, in accord with expectations for low-concentration clusters. On the other hand, a comparison of the global mass function of Pal 5 with that of ω Cen and M55 indicates an increasing deficiency of stars with progressively lower masses. A fit of the observed luminosity function to theoretical models indicates a mass function for Pal 5 of dN/dm~m-0.5, which is notably more deficient in low-mass stars than other globular clusters that have been studied with the Hubble Space Telescope. The flatness of the mass function is consistent with models of the dynamical evolution of globular clusters that have lost ~90% of their original stellar mass. We suggest that, like NGC 6712, Pal 5 has lost a large percentage of its original stellar content as a result of tidal shocking. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555.

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

    SciTech Connect

    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.

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

    SciTech Connect

    Park, KwangHo; Khandai, Nishikanta; Matteo, Tiziana Di; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu

    2015-09-18

    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 ≤ z ≤ 3.0 using the [OII] emission line luminosity L([OII]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [OII] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([OII]) = 1043.0 erg s–1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [OII] galaxies, but still displaying a good match with observations below L([OII]) = 1041.6 erg s–1. Based on the validity in reproducing the properties of [OII] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [OII] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from –3 to –2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)–1 at z ≤ 2 while the faint end evolves as ~3(z + 1)–1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [OIII] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. As a result, we show that the auto-correlation function of [OII] and [OIII] emitting galaxies shows a rapid evolution from z = 2 to 1.

  1. Towards a New Distance Scale and Luminosity Function for Nearby Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Frew, David J.; Parker, Q. A.

    The local planetary nebula (PN) census is dominated by extremely evolved examples, and until recently, was incomplete. New discoveries from the AAO/UKST Hα Survey and SHASSA, have partially remedied this problem. In addition, we find that some currently accepted nearby PNe are in fact Strömgren spheres in the ISM ionised by a hot white dwarf. Distance estimates for a robust sample of calibrating PNe from the literature, plus new distances for a number of highly evolved PNe, have allowed a new Hα surface brightness - radius relationship to be devised as a useful distance indicator. It covers >6 dex in SB, and while the spread in SB is ˜1 dex at a given radius, optically thick (mainly bipolar and bipolar-core) PNe tend to populate the upper bound of the trend, while common-envelope PNe and very high-excitation PNe form a sharp lower boundary. Hence, distances can be estimated for all remaining local PNe, allowing the definition of a relatively complete census of PNe in the solar neighbourhood within 1.0 kpc. This provides a first look at the faint end of the PN luminosity function, and new estimates of the space density, scale height, total number, and birth rate of Galactic PNe.

  2. Evolution of the Mass and Luminosity Functions of Globular Star Clusters

    NASA Astrophysics Data System (ADS)

    Goudfrooij, Paul; Fall, S. Michael

    2016-12-01

    We reexamine the dynamical evolution of the mass and luminosity functions of globular star clusters (GCMF and GCLF). Fall & Zhang (2001, FZ01) showed that a power-law MF, as commonly seen among young cluster systems, would evolve by dynamical processes over a Hubble time into a peaked MF with a shape very similar to the observed GCMF in the Milky Way and other galaxies. To simplify the calculations, the semi-analytical FZ01 model adopted the “classical” theory of stellar escape from clusters, and neglected variations in the M/L ratios of clusters. Kruijssen & Portegies Zwart (2009, KPZ09) modified the FZ01 model to include “retarded” and mass-dependent stellar escape, the latter causing significant M/L variations. KPZ09 asserted that their model was compatible with observations, whereas the FZ01 model was not. We show here that this claim is not correct; the FZ01 and KPZ09 models fit the observed Galactic GCLF equally well. We also show that there is no detectable correlation between M/L and L for GCs in the Milky Way and Andromeda galaxies, in contradiction with the KPZ09 model. Our comparisons of the FZ01 and KPZ09 models with observations can be explained most simply if stars escape at rates approaching the classical limit for high-mass clusters, as expected on theoretical grounds.

  3. The VVDS type-1 AGN sample: the faint end of the luminosity function

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Zamorani, G.; Gavignaud, I.; Marano, B.; Paltani, S.; Mathez, G.; Møller, P.; Picat, J. P.; Cirasuolo, M.; Lamareille, F.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Hatziminaoglou, E.; Polletta, M.; Bondi, M.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-09-01

    In a previous paper (Gavignaud et al. 2006, A&A, 457, 79), we presented the type-1 Active Galactic Nuclei (AGN) sample obtained from the first epoch data of the VIMOS-VLT Deep Survey (VVDS). The sample consists of 130 faint, broad-line AGN with redshift up to z=5 and 17.5Luminosity Function up to z=3.6 derived from this sample, we compare our results with previous results from brighter samples both at low and at high redshift and finally, through the estimate of the bolometric luminosity function, we compare them also with the results from X-ray and mid-IR selected samples. Our data, more than one magnitude fainter than previous optical surveys, allow us to constrain the faint part of the luminosity function up to high redshift. A comparison of our data with the 2dF sample at low redshift (1 < z < 2.1) shows that the VVDS data can not be well fitted with the PLE models derived by previous samples. Qualitatively, this appears to be due to the fact that our data suggest the presence of an excess of faint objects at low redshift (1.0luminosity functions, over a wide range of redshift and luminosity, is a luminosity dependent density evolution (LDDE) model, similar to those derived from the major X-surveys. Such a parameterization allows the redshift of the AGN space density peak to change as a function of luminosity and explains the excess of faint AGN that we find at 1.0 < z < 1.5. On the basis of this model we find, for the

  4. Luminosity and Stellar Mass Functions of Local Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Pérez-González, Pablo G.; Gallego, Jesús; Zamorano, Jaime; Alonso-Herrero, Almudena; Gil de Paz, Armando; Aragón-Salamanca, Alfonso

    2003-04-01

    We present the optical and near-infrared luminosity and mass functions of the local star-forming galaxies in the Universidad Complutense de Madrid (UCM) Survey. A bivariate method that explicitly deals with the Hα selection of the survey is used when estimating these functions. Total stellar masses have been calculated on a galaxy-by-galaxy basis taking into account differences in star formation histories. The main difference between the luminosity distributions of the UCM sample and the luminosity functions of the local galaxy population is a lower normalization (φ*), indicating a lower global volume density of UCM galaxies. The typical near-infrared luminosity (L*) of local star-forming galaxies is fainter than that of normal galaxies. This is a direct consequence of the lower stellar masses of our objects. However, at optical wavelengths (B and r), the luminosity enhancement arising from the young stars leads to M* values that are similar to those of normal galaxies. The fraction of the total optical and near-infrared luminosity density in the local universe associated with star-forming galaxies is 10%-20%. Fitting the total stellar mass function using a Schechter parameterization, we obtain α=-1.15+/-0.15, logM*=10.82+/-0.17 Msolar, and logφ*=-3.04+/-0.20 Mpc-3. This gives an integrated total stellar mass density of 107.83+/-0.07 Msolar Mpc-3 in local star-forming galaxies (H0=70 km s-1 Mpc-1, ΩM=0.3, and Λ=0.7). The volume-averaged burst strength of the UCM galaxies is b=0.04+/-0.01, defined as the ratio of the mass density of stars formed in recent bursts (with an age of <10 Myr) to the total stellar mass density in UCM galaxies. Finally, we derive that in the local universe, 13%+/-3% of the total baryon mass density in the form of stars is associated with star-forming galaxies.

  5. Effect of long-term intensity variations on pulsar searches and the pulsar luminosity function

    NASA Technical Reports Server (NTRS)

    Krishnamohan, S.

    1981-01-01

    Long-term intensity data for five pulsars are used to obtain the probability density distribution of intensities for each pulsar, and it is found that they are described satisfactorily by chi-squared distributions. Based on these distributions, the number of new pulsars expected to be found on repeatedly searching the same region of the sky with the same sensitivity is given. Nearly 25 percent more new pulsars are expected to be found on the first repeat search. It is also shown that the luminosity function deduced from either a single survey or surveys with very different sensitivities is not affected by the omission of flux density variations in the calculation of selection effects. Finally, a method is proposed for deriving the luminosity function by combining the different searches of a given area on the basis of a probabilistic approach to the evaluation of selection effects.

  6. LUMINOSITY FUNCTIONS AND POINT-SOURCE PROPERTIES FROM MULTIPLE CHANDRA OBSERVATIONS OF M81

    SciTech Connect

    Sell, P. H.; Pooley, D.; Heinz, S.; Zezas, A.; Homan, J.; Lewin, W. H. G.

    2011-07-01

    We present an analysis of 15 Chandra observations of the nearby spiral galaxy M81 taken over the course of six weeks in 2005 May-July. Each observation reaches a sensitivity of {approx}10{sup 37} erg s{sup -1}. With these observations and one previous deeper Chandra observation, we compile a master source list of 265 point sources, extract and fit their spectra, and differentiate basic populations of sources through their colors. We also carry out variability analyses of individual point sources and of X-ray luminosity functions (XLFs) in multiple regions of M81 on timescales of days, months, and years. We find that, despite measuring significant variability in a considerable fraction of sources, snapshot observations provide a consistent determination of the XLF of M81. We also fit the XLFs for multiple regions of M81 and, using common parameterizations, compare these luminosity functions to those of two other spiral galaxies, M31 and the Milky Way.

  7. The UV Luminosity Function at 6 < z < 10 from the Hubble Frontier Fields

    NASA Astrophysics Data System (ADS)

    Livermore, Rachael C.; Finkelstein, Steven L.; Lotz, Jennifer M.

    2017-01-01

    The Hubble Frontier Fields program has obtained deep optical and near-infrared Hubble Space Telescope imaging of six galaxy clusters and associated parallel fields. The depth of the imaging (m_AB ~ 29) means we can identify faint galaxies at z > 6, and those in the cluster fields also benefit from magnification due to strong gravitational lensing that allows us to reach intrinsic absolute magnitudes of M_UV ~ -12.5 at z ~ 6. Here, we present the UV luminosity functions at 6 < z < 10 from the complete Hubble Frontier Fields data, revealing a steep faint-end slope that extends to the limits of the data. The lack of any apparent turnover in the luminosity functions means that faint galaxies in the early Universe may have provided sufficient ionizing radiation to sustain reionization.

  8. COMBO-17 measurements of the effect of environment on the type-dependent galaxy luminosity function

    NASA Astrophysics Data System (ADS)

    Phleps, S.; Wolf, C.; Peacock, J. A.; Meisenheimer, K.; van Kampen, E.

    2007-06-01

    We have developed a method to calculate overdensities in multicolour surveys, facilitating a direct comparison of the local density contrast measured using galaxy samples that have different redshift error distributions, i.e. for red and blue, or bright and faint galaxies, respectively. We calculate overdensities in small redshift slices (Δ z =0.02, which at z=0.3 corresponds roughly to Δ r_comoving=53~h-1 Mpc) for 9176 galaxies with R≤23.65, MB(Vega)-5log h≤-18, and z≤ 0.7, in three COMBO-17 fields (measuring 31'×31' each). The mean redshift errors of this sample are approximately σ_z/(1+z)≃ 0.015. In the Chandra Deep Field South we identify a region that is underdense by almost a factor 2 compared to the other two fields in the same redshift range (0.25⪉ z ⪉ 0.4). This can be used for an investigation of the variation of the colour-dependent luminosity function with environment: We calculate the luminosity function in this redshift range for red sequence and blue cloud galaxies (as defined by Bell et al. 2004) in each of the fields separately. While the luminosity function of the blue galaxies remains unaffected by different density contrasts, the luminosity function of the red galaxies clearly has a more positive faint-end slope in the Chandra Deep Field South as compared to the other two COMBO-17 fields. The underdensity there is thus mainly due to a deficiency of faint red galaxies. This result is in qualitative agreement with the trends seen at z=0.1, e.g. in the 2dFGRS (Croton et al. 2005), or in the SDSS (Zandivarez et al. 2006).

  9. The 2dF Galaxy Redshift Survey: spectral types and luminosity functions

    NASA Astrophysics Data System (ADS)

    Folkes, Simon; Ronen, Shai; Price, Ian; Lahav, Ofer; Colless, Matthew; Maddox, Steve; Deeley, Kathryn; Glazebrook, Karl; Bland-Hawthorn, Joss; Cannon, Russell; Cole, Shaun; Collins, Chris; Couch, Warrick; Driver, Simon P.; Dalton, Gavin; Efstathiou, George; Ellis, Richard S.; Frenk, Carlos S.; Kaiser, Nick; Lewis, Ian; Lumsden, Stuart; Peacock, John; Peterson, Bruce A.; Sutherland, Will; Taylor, Keith

    1999-09-01

    We describe the 2dF Galaxy Redshift Survey (2dFGRS) and the current status of the observations. In this exploratory paper, we apply a principal component analysis to a preliminary sample of 5869 galaxy spectra and use the two most significant components to split the sample into five spectral classes. These classes are defined by considering visual classifications of a subset of the 2dF spectra, and also by comparison with high-quality spectra of local galaxies. We calculate a luminosity function for each of the different classes and find that later-type galaxies have a fainter characteristic magnitude, and a steeper faint-end slope. For the whole sample we find M*=-19.7 (for Ω=1, H_0=100kms^-1Mpc^-1), α=-1.3, φ*=0.017. For class 1 (`early-type') we find M*=-19.6, α=-0.7, while for class 5 (`late-type') we find M*=-19.0, α=-1.7. The derived 2dF luminosity functions agree well with other recent luminosity function estimates.

  10. The luminosity functions of embedded stellar clusters. 1: Method of solution and analytic results

    NASA Technical Reports Server (NTRS)

    Fletcher, Andre B.; Stahler, Steven W.

    1994-01-01

    We describe a method for computing the history of the luminosity function in a young cluster still forming within a molecular cloud complex. Our method, which utilizes detailed results from stellar evolution theory, assumes that clusters arise from the continuous collapse of dense cloud cores over a protracted period of time. It is also assumed that stars reaching the main sequence are distributed in mass according to a prescribed initial mass function (IMF). We keep track separately of the contributions to the luminosity function from the populations of protostars, pre-main-sequence stars, and main-sequence stars. We derive expressions for the fractional contribution of these populations to both the total number of stars produced and the total cluster luminosity. In our model, the number of protostars rises quickly at first, but then levels off to a nearly constant value, which it maintains until the dispersal of the cloud complex. The number fraction of protostars always decreases with time. Averaged over the life of the parent cloud, this fraction is typically a few percent. The protostar mass distribution can be expressed as an integral over the IMF.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  13. The Bivariate Luminosity--HI Mass Distribution Function of Galaxies based on the NIBLES Survey

    NASA Astrophysics Data System (ADS)

    Butcher, Zhon; Schneider, Stephen E.; van Driel, Wim; Lehnert, Matt

    2016-01-01

    We use 21cm HI line observations for 2610 galaxies from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) to derive a bivariate luminosity--HI mass distribution function. Our HI survey was selected to randomly probe the local (900 < cz < 12,000 km/s) galaxy population in each 0.5 mag wide bin for the absolute z-band magnitude range of -13.5 < Mz < -24 without regard to morphology or color. This targeted survey allowed more on-source integration time for weak and non-detected sources, enabling us to probe lower HI mass fractions and apply lower upper limits for non-detections than would be possible with the larger blind HI surveys. Additionally, we obtained a factor of four higher sensitivity follow-up observations at Arecibo of 90 galaxies from our non-detected and marginally detected categories to quantify the underlying HI distribution of sources not detected at Nançay. Using the optical luminosity function and our higher sensitivity follow up observations as priors, we use a 2D stepwise maximum likelihood technique to derive the two dimensional volume density distribution of luminosity and HI mass in each SDSS band.

  14. A finer view of the conditional galaxy luminosity function and magnitude-gap statistics

    NASA Astrophysics Data System (ADS)

    Trevisan, M.; Mamon, G. A.

    2017-10-01

    The gap between first- and second-ranked galaxy magnitudes in groups is often considered a tracer of their merger histories, which in turn may affect galaxy properties, and also serves to test galaxy luminosity functions (LFs). We remeasure the conditional luminosity function (CLF) of the Main Galaxy Sample of the SDSS in an appropriately cleaned subsample of groups from the Yang catalogue. We find that, at low group masses, our best-fitting CLF has steeper satellite high ends, yet higher ratios of characteristic satellite to central luminosities in comparison with the CLF of Yang et al. The observed fractions of groups with large and small magnitude gaps as well as the Tremaine & Richstone statistics are not compatible with either a single Schechter LF or with a Schechter-like satellite plus lognormal central LF. These gap statistics, which naturally depend on the size of the subsamples, and also on the maximum projected radius, Rmax, for defining the second brightest galaxy, can only be reproduced with two-component CLFs if we allow small gap groups to preferentially have two central galaxies, as expected when groups merge. Finally, we find that the trend of higher gap for higher group velocity dispersion, σv, at a given richness, discovered by Hearin et al., is strongly reduced when we consider σv in bins of richness, and virtually disappears when we use group mass instead of σv. This limits the applicability of gaps in refining cosmographic studies based on cluster counts.

  15. The impact of dust in host galaxies on quasar luminosity functions

    NASA Astrophysics Data System (ADS)

    Shirakata, Hikari; Okamoto, Takashi; Enoki, Motohiro; Nagashima, Masahiro; Kobayashi, Masakazu A. R.; Ishiyama, Tomoaki; Makiya, Ryu

    2015-06-01

    We have investigated effects of dust attenuation on quasar luminosity functions at z ˜ 2 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, ˜2 mag in the B-band. Assuming the empirical bolometric corrections for active galactic nuclei (AGNs) by Marconi et al., we find that this dust attenuation is too strong to explain the B-band and X-ray quasar luminosity functions simultaneously. We consider two possible mechanisms that weaken the dust attenuation. As such a mechanism, we introduce a time delay for AGN activity, that is, gas fuelling to a central black hole starts sometime after the beginning of the starburst induced by a major merger. The other is the anisotropy in the dust distribution. We find that in order to make the dust attenuation of the quasars negligible, either the gas accretion into the black holes has to be delayed at least three times the dynamical time-scale of their host bulges or the dust covering factor is as small as ˜0.1.

  16. Galaxy luminosity functions, M/L ratios, and closure of the Universe - Numbers and problems

    NASA Technical Reports Server (NTRS)

    Felten, J. E.

    1985-01-01

    Data on the luminosity function (LF) of galaxies are reviewed and compared, and the result of Kirshner et al. (1983) giving a 'standard LF' is chosen as a best guess. Departures from the 'standard LF' for specific galaxy types and environments (clusters, groups, field) are discussed briefly. A luminosity density of about 1.4 x 10 to the -2nd h 'galaxies' per cubic megaparsec is obtained. The mean M/L ratio needed to give critical cosmological density (Omega sub 0 = 1) is then 920 h in solar units on the face-on magnitude system. Comparison with measured M/L ratios for galaxies and clusters, and with constraints imposed by inflation and nucleosynthesis, poses two problems of 'invisible mass'.

  17. CO luminosity function from Herschel-selected galaxies and the contribution of AGN

    NASA Astrophysics Data System (ADS)

    Vallini, L.; Gruppioni, C.; Pozzi, F.; Vignali, C.; Zamorani, G.

    2016-02-01

    We derive the carbon monoxide (CO) luminosity function (LF) for different rotational transitions [i.e. (1-0), (3-2), (5-4)] starting from the Herschel LF by Gruppioni et al. and using appropriate LCO-LIR conversions for different galaxy classes. Our predicted LFs fit the data so far available at z ≈ 0 and 2. We compare our results with those obtained by semi-analytical models (SAMs): while we find a good agreement over the whole range of luminosities at z ≈ 0, at z ≈ 1 and z ≈ 2, the tension between our LFs and SAMs in the faint and bright ends increases. We finally discuss the contribution of luminous active galactic nucleus (LX > 1044 erg s- 1) to the bright end of the CO LF concluding that they are too rare to reproduce the actual CO LF at z ≈ 2.

  18. The luminosity and stellar mass functions of red W1-W2 galaxies

    NASA Astrophysics Data System (ADS)

    O'Connor, J. A.; Rosenberg, J. L.; Satyapal, S.; Secrest, N. J.

    2016-11-01

    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 active galactic nuclei (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 per cent of nearby galaxies. However, the reddest galaxies are a rising fraction of the low-mass galaxy population. Identifying the lowest mass (M < 108 M⊙) red ([3.4]-[4.6] > 0.8) galaxies as AGN is surprising given that none are optical AGN or composites, in contrast with their more massive (M > 1010 M⊙) red galaxy counterparts that are dominated by optical AGN and composites (86.4 per cent). We also show that these low-mass red galaxies are associated with higher specific star formation rates than their bluer counterparts. While the properties of this relatively rare segment of nearby low-mass galaxies are intriguing, particularly if they are associated with AGN activity, there is not yet enough evidence to determine whether it is AGN or unusual star formation that is driving red colours in these systems.

  19. PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2 < z < 1

    NASA Astrophysics Data System (ADS)

    Skibba, Ramin A.; Smith, M. Stephen M.; Coil, Alison L.; Moustakas, John; Aird, James; Blanton, Michael R.; Bray, Aaron D.; Cool, Richard J.; Eisenstein, Daniel J.; Mendez, Alexander J.; Wong, Kenneth C.; Zhu, Guangtun

    2014-04-01

    We present measurements of the luminosity and color-dependence of galaxy clustering at 0.2 < z < 1.0 in the Prism Multi-object Survey. We quantify the clustering with the redshift-space and projected two-point correlation functions, ξ(rp , π) and wp (rp ), using volume-limited samples constructed from a parent sample of over ~130, 000 galaxies with robust redshifts in seven independent fields covering 9 deg2 of sky. We quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. We find that red galaxies have stronger small-scale (0.1 Mpc h -1 < rp < 1 Mpc h -1) clustering and steeper correlation functions compared to blue galaxies, as well as a strong color dependent clustering within the red sequence alone. We interpret our measured clustering trends in terms of galaxy bias and obtain values of b gal ≈ 0.9-2.5, quantifying how galaxies are biased tracers of dark matter depending on their luminosity and color. We also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, we measure the evolution of the clustering strength and bias, and we do not detect statistically significant departures from passive evolution. We argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z ~ 1. Finally, using jackknife subsampling methods, we find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; we find that "cosmic variance" can be a significant source of uncertainty for high-redshift clustering measurements.

  20. Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities

    SciTech Connect

    Wang, Lifan; Strovink, Mark; Conley, Alexander; Goldhaber,Gerson; Kowalski, Marek; Perlmutter, Saul; Siegrist, James

    2005-12-14

    Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least an equal share likely belongs to B{sub BV}. SN magnitudes measured using maximum-luminosity or cmagic methods show comparable rms deviations of order {approx}0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km s{sup -1} on the rms peculiar velocity of nearby SNe relative to the Hubble flow.

  1. The luminosity function at z ∼ 8 from 97 Y-band dropouts: Inferences about reionization

    SciTech Connect

    Schmidt, Kasper B.; Treu, Tommaso; Kelly, Brandon C.; Trenti, Michele; Bradley, Larry D.; Stiavelli, Massimo; Oesch, Pascal A.; Shull, J. Michael

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ∼ 8 Lyman break galaxies, LBGs) based on 350 arcmin{sup 2} of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin{sup 2} of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ∼ 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 ≤ m{sub J} ≤ 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ∼ 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M{sup ⋆}=−20.15{sub −0.38}{sup +0.29}, a faint-end slope of α=−1.87{sub −0.26}{sup +0.26}, and a number density of log{sub 10} ϕ{sup ⋆}[Mpc{sup −3}]=−3.24{sub −0.24}{sup +0.25}. Integrated down to M = –17.7, this luminosity function yields a luminosity density log{sub 10} ϵ[erg s{sup −1} Hz{sup −1} Mpc{sup −3}]=25.52{sub −0.05}{sup +0.05}. Our luminosity function analysis is consistent with previously published determinations within 1σ. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of

  2. A study of the luminosity function for field galaxies. [non-rich-cluster galaxies

    NASA Technical Reports Server (NTRS)

    Felten, J. E.

    1977-01-01

    Nine determinations of the luminosity function (LF) for field galaxies are analyzed and compared. Corrections for differences in Hubble constants, magnitude systems, galactic absorption functions, and definitions of the LF are necessary prior to comparison. Errors in previous comparisons are pointed out. After these corrections, eight of the nine determinations are in fairly good agreement. The discrepancy in the ninth appears to be mainly an incompleteness effect. The LF data suggest that there is little if any distinction between field galaxies and those in small groups.

  3. Star Formation Rate at Z = 0.2 derived from H alpha luminosities: constraint on the reddening

    NASA Astrophysics Data System (ADS)

    Tresse, L.; Maddox, S. J.

    We discuss the relative merits of using UV and H_alpha as star formation indicators from galaxy surveys. In particular, comparing UV and H_alpha in the CFRS gives a limit of a factor 2.5 for the UV(2800 Angs.) flux extinction from dust, using the conversion factors of Madau et al. 1998 (Salpeter IMF, 0.1-125 solar mass). Our strong correlation between B and H_alpha luminosities argues for a universal IMF slope. The H_alpha luminosity function at z = 0.2 shows a faint end slope of alpha = -1.35, which is consistent with fading of short bursts of star formation. We also discuss the contribution of AGN to UV and H_alpha luminosities.

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

    NASA Astrophysics Data System (ADS)

    Albani, V. V. L.; Iribarrem, A. S.; Ribeiro, M. B.; Stoeger, W. R.

    2007-03-01

    This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number density statistics of the galaxy distribution as discussed in Ribeiro, namely, the differential density γ and the integral differential density γ*. By applying the theory advanced by Ribeiro & Stoeger, 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 γ and γ* with various cosmological distance definitions, namely, area distance, luminosity distance, galaxy area distance, and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey, and γ and γ* are calculated for two cosmological models: Einstein-de Sitter and an Ωm0=0.3, ΩΛ0=0.7 standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in Ribeiro, as well as showing that plots of γ and γ* against the luminosity and redshift distances indicate that the CNOC2 galaxy distribution follows a power-law pattern for redshifts higher than 0.1. These findings support Ribeiro's theoretical proposition that using different cosmological distance measures in statistical analyses of galaxy surveys can lead to significant ambiguity in drawing conclusions about the behavior of the observed large-scale distribution of galaxies.

  5. The luminosity function of quasars and its evolution: A comparison of optically selected quasars and quasars found in radio catalogs

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1973-01-01

    The luminosity function of quasars and its evolution are discussed, based on comparison of available data on optically selected quasars and quasars found in radio catalogs. It is assumed that the red shift of quasars is cosmological and the results are expressed in the framework of the Lambda = 0, Q sub Q = 1 cosmological model. The predictions of various density evolution laws are compared with observations of an optically selected sample of quasars and quasar samples from radio catalogs. The differences between the optical luminosity functions, the red shift distributions and the radio to optical luminosity ratios of optically selected quasars and radio quasars rule out luminosity functions where there is complete absence of correlation between radio and optical luminosities. These differences also imply that Schmidt's (1970) luminosity function, where there exists a statistical correlation between radio and optical luminosities, although may be correct for high red shift objects, disagrees with observation at low red shifts. These differences can be accounted for by postulating existence of two classes (1 and 2) of objects.

  6. Deep spectroscopy of nearby galaxy clusters - I. Spectroscopic luminosity function of Abell 85

    NASA Astrophysics Data System (ADS)

    Agulli, I.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Dalla Vecchia, C.; Diaferio, A.; Barrena, R.; Dominguez Palmero, L.; Yu, H.

    2016-05-01

    We present a new deep spectroscopic catalogue for Abell 85, within 3.0 × 2.6 Mpc2 and down to Mr ˜ Mr^{ast } +6. Using the Visible Multi-Object Spectrograph at the Very Large Telescope and the AutoFiber 2 at the William Herschel Telescope, we obtained almost 1430 new redshifts for galaxies with mr ≤ 21 mag and <μe,r> ≤ 24 mag arcsec-2. These redshifts, together with Sloan Digital Sky Survey Data Release 6 and NASA/IPAC Extragaalctic Database spectroscopic information, result in 460 confirmed cluster members. This data set allows the study of the luminosity function (LF) of the cluster galaxies covering three orders of magnitudes in luminosities. The total and radial LFs are best modelled by a double Schechter function. The normalized LFs show that their bright (Mr ≤ -21.5) and faint (Mr ≥ -18.0) ends are independent of clustercentric distance and similar to the field LFs unlike the intermediate luminosity range (-21.5 ≤ Mr ≤ -18.0). Similar results are found for the LFs of the dominant types of galaxies: red, passive, virialized and early-infall members. On the contrary, the LFs of blue, star forming, non-virialized and recent-infall galaxies are well described by a single Schechter function. These populations contribute to a small fraction of the galaxy density in the innermost cluster region. However, in the outskirts of the cluster, they have similar densities to red, passive, virialized and early-infall members at the LF faint end. These results confirm a clear dependence of the colour and star formation of Abell 85 members in the cluster centric distance.

  7. Early black holes in cosmological simulations: luminosity functions and clustering behaviour

    NASA Astrophysics Data System (ADS)

    DeGraf, Colin; Di Matteo, Tiziana; Khandai, Nishikanta; Croft, Rupert; Lopez, Julio; Springel, Volker

    2012-08-01

    We examine predictions for the quasar luminosity functions (QLFs) and quasar clustering at high redshift (z ≥ 4.75) using MassiveBlack, our new hydrodynamic cosmological simulation which includes a self-consistent model for black hole (BH) growth and feedback. We show that the model reproduces the Sloan QLF within observational constraints at z ≥ 5. We find that the high-z QLF is consistent with a redshift-independent occupation distribution of BHs among dark matter haloes (which we provide) such that the evolution of the QLF follows that of the halo mass function. The sole exception is the bright end at z = 6 and 7, where BHs in high-mass haloes tend to be unusually bright due to extended periods of Eddington growth caused by high-density cold flows into the halo centre. We further use these luminosity functions to make predictions for the number density of quasars in upcoming surveys, predicting that there should be ˜119 ± 28 (˜87 ± 28) quasars detectable in the F125W band of the WIDE (DEEP) fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) from z = 5 to 6, ˜19 ± 7 (˜18 ± 9) from z = 6 to 7 and ˜1.7 ± 1.5 (˜1.5 ± 1.5) from z = 7 to 8. We also investigate quasar clustering, finding that the correlation length is fully consistent with current constraints for Sloan quasars (r0 ˜ 17 h-1 Mpc at z = 4 for quasars above mi = 20.2) and grows slowly with redshift up to z = 6 (r0 ˜ 22 h-1 Mpc). Finally, we note that the quasar clustering strength depends weakly on luminosity for low LBH, but gets stronger at higher LBH as the BHs are found in higher mass haloes.

  8. A MUSE View of the HDFS: The Lyα Luminosity Function out to z~6

    NASA Astrophysics Data System (ADS)

    Drake, Alyssa B.; Guiderdoni, Bruno; Blaizot, Jérémy; Richard, Johan; Bacon, Roland; Garel, Thibault; Hashimoto, Takuya

    We present preliminary results from MUSE on the Lyα luminosity function in the Hubble Deep Field South (HDFS). Using a large homogeneous sample of LAEs selected through blind spectroscopy, we utilise the unprecedented detection power of MUSE to study the progenitors of L* galaxies back to when the Universe was just ~2 Gyr old. We present these results in the context of the current literature, and highlight the importance of the forthcoming Hubble Ultra Deep Field (HUDF) study with MUSE, which will increase the size of our sample by a factor of ~ 10.

  9. Evolution Of The Cluster Optical Galaxy Luminosity Function In The Cfhtls

    NASA Astrophysics Data System (ADS)

    Sarron, Florian; Martinet, Nicolas; Adami, Christophe; Durret, Florence

    2017-06-01

    There is some disagreement in the literature concerning the evolution with redshift of the galaxy luminosity function (GLF) in galaxy clusters. Indeed, it is still unclear whether the red sequence (RS) is enriched by efficient quenching of blue late-type galaxies inside the cluster from z of about 1, or if this RS is built at higher redshift. Solving this contradiction is important to understand the physical processes driving the quenching of galaxies. However, the study of the GLF evolution has been limited to small samples and these different conclusions could be due to cluster to cluster variations. To explore this possibility, we applied our new version of the Adami and MAzure Cluster FInder (AMACFI) to the Canada France Hawaii Telescope Legacy Survey (CFHTLS) W1 field. We thus built a catalogue of thousands of cluster candidates up to z of about 1. We present the selection function of our detection algorithm. We study the evolution of the galaxy luminosity function of galaxy clusters with both redshift and cluster mass, and show preliminary results. Taking advantage of our large sample of clusters, we shall be able to break the degeneracy between redshift and mass dependence in the near future.

  10. The Dragonfly Nearby Galaxies Survey. III. The Luminosity Function of the M101 Group

    NASA Astrophysics Data System (ADS)

    Danieli, Shany; van Dokkum, Pieter; Merritt, Allison; Abraham, Roberto; Zhang, Jielai; Karachentsev, I. D.; Makarova, L. N.

    2017-03-01

    We obtained follow-up HST observations of the seven low surface brightness galaxies discovered with the Dragonfly Telephoto Array in the field of the massive spiral galaxy M101. Out of the seven galaxies, only three were resolved into stars and are potentially associated with the M101 group at D = 7 Mpc. Based on HST ACS photometry in the broad F606W and F814W filters, we use a maximum likelihood algorithm to locate the Tip of the Red Giant Branch in galaxy color–magnitude diagrams. Distances are {6.38}-0.35+0.35,{6.87}-0.30+0.21 and {6.52}-0.27+0.25 {Mpc} and we confirm that they are members of the M101 group. Combining the three confirmed low-luminosity satellites with previous results for brighter group members, we find the M101 galaxy group to be a sparsely populated galaxy group consisting of seven group members, down to M V = ‑9.2 mag. We compare the M101 cumulative luminosity function to that of the Milky Way and M31. We find that they are remarkably similar; in fact, the cumulative luminosity function of the M101 group gets even flatter for fainter magnitudes, and we show that the M101 group might exhibit the two known small-scale flaws in the ΛCDM model, namely “the missing satellite” problem and the “too big to fail” problem. Kinematic measurements of M101's satellite galaxies are required to determine whether the “too big to fail” problem does in fact exist in the M101 group.

  11. PRIMUS: Galaxy clustering as a function of luminosity and color at 0.2 < z < 1

    SciTech Connect

    Skibba, Ramin A.; Smith, M. Stephen M.; Coil, Alison L.; Mendez, Alexander J.; Moustakas, John; Aird, James; Blanton, Michael R.; Bray, Aaron D.; Eisenstein, Daniel J.; Cool, Richard J.; Wong, Kenneth C.; Zhu, Guangtun

    2014-04-01

    We present measurements of the luminosity and color-dependence of galaxy clustering at 0.2 < z < 1.0 in the Prism Multi-object Survey. We quantify the clustering with the redshift-space and projected two-point correlation functions, ξ(r{sub p} , π) and w{sub p} (r{sub p} ), using volume-limited samples constructed from a parent sample of over ∼130, 000 galaxies with robust redshifts in seven independent fields covering 9 deg{sup 2} of sky. We quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. We find that red galaxies have stronger small-scale (0.1 Mpc h {sup –1} < r{sub p} < 1 Mpc h {sup –1}) clustering and steeper correlation functions compared to blue galaxies, as well as a strong color dependent clustering within the red sequence alone. We interpret our measured clustering trends in terms of galaxy bias and obtain values of b {sub gal} ≈ 0.9-2.5, quantifying how galaxies are biased tracers of dark matter depending on their luminosity and color. We also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, we measure the evolution of the clustering strength and bias, and we do not detect statistically significant departures from passive evolution. We argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z ∼ 1. Finally, using jackknife subsampling methods, we find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; we find that 'cosmic variance' can be a significant source of uncertainty for high-redshift clustering measurements.

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

    NASA Technical Reports Server (NTRS)

    Beckmann, V.; Soldi, S.; Shrader, C. R.; Gehrels, N.; Produit, N.

    2006-01-01

    We have compiled a complete, significance limited extragalactic sample based on approximately 25,000 deg(sup 2) to a limiting flux of 3 x 10(exp -11) ergs per square centimeter per second. (approximately 7,000 deg(sup 2)) to a flux limit of 10(exp -11) ergs per square centimeter per second)) 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 plus or minus 0.11. The integration of the cumulative flux per unit area leads to f(sub 20-40 keV) = 2.6 x 10(exp -10) ergs per square centimeter per second per sr(sup -1) which is about 1% of the known 20-40 keV X-ray background. We present the first luminosity function of AGN in the 20-40 keV energy range, based on 68 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 (sub 1) = 0.9 below, and gamma (sub 2) = 2.2 above the turn-over luminosity of L(sub *), = 4.6 x 10(sup 43) ergs per second. The emissivity of all INTEGRAL AGNs per unit volume is W(sub 20-40keV)(greater than 10(sup 41) ergs per second) = 2.8 x 10(sup 38) ergs per second h(sup 3)(sub 70) Mpc(sup -3). These results are consistent with those derived in the 2-20keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (z(raised bar) = 0.022)), only limited conclusions can be drawn for the evolution of AGNs in this energy band. But the objects explaining the peak in the cosmic X-ray background are likely to be either low luminosity AGN (L(sub x) less than 10(sup 41) ergs per second) or of other type, such as intermediate mass black holes, clusters, and star forming regions.

  13. A mixture spatial point pattern model for the quasar luminosity function

    NASA Astrophysics Data System (ADS)

    Payandeh Najafabadi, Amir T.; Baniasadi, Fatemeh

    2011-10-01

    Consider the problem of estimating the Quasar Luminosity Function (QLF). In a 2007 Ph.D. dissertation, Hugeback considers the QLF as a nonhomogeneous poisson process and estimates the intensity function under SDSS DR3 data (The University of Chicago, AAT 3273021). The present study follows Hugeback's approach but introduces a mixture component which improves Hugeback's model in several respects. Namely, the database is partitioned into two groups according to redshift: z < 2.75 and z ⩾ 2.75. Next, a mixture model for the QLF was derived using the concept of pseudolikelihood, the addition of a K function to allow for inter-point interaction, and evaluation of residuals diagnostic plots. This mixture model (i) improves the deviance of Hugeback's model, and (ii) satisfies residual assumptions that are violated under Hugeback's model. Moreover, this study confirms Hugeback's finding of inhomogeneity in the QLF, and provides stronger evidence for the existence of an interaction between redshift and absolute magnitude.

  14. COSMOLOGICAL DEPENDENCE OF THE MEASUREMENTS OF LUMINOSITY FUNCTION, PROJECTED CLUSTERING AND GALAXY-GALAXY LENSING SIGNAL

    SciTech Connect

    More, Surhud

    2013-11-10

    Observables such as the galaxy luminosity function, Φ(M), projected galaxy clustering, w {sub p}(r {sub p}), and the galaxy-galaxy lensing signal, ΔΣ(r {sub p}), are often measured from galaxy redshift surveys assuming a fiducial cosmological model for calculating distances to, and between galaxies. There are a growing number of studies that perform joint analyses of these measurements and constrain cosmological parameters. We quantify the amount by which such measurements systematically vary as the fiducial cosmology used for the measurements is changed, and show that these effects can be significant at high redshifts (z ∼ 0.5). Cosmological analyses (or halo occupation distribution analyses) that use the luminosity function, clustering and the galaxy-galaxy lensing signal but ignore such systematic effects may bias the inference of the parameters. We present a simple way to account for the differences in the cosmological model used for the measurements and those used for the prediction of observables, thus allowing a fair comparison between models and data.

  15. Spitzer Local Volume Legacy (LVL) Star-Forming Regions: Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Lee, Janice C.; LVL Team

    2015-01-01

    The conversion of gas into stars is one of the most fundamental processes in the universe, yet the effects of environmental conditions are poorly constrained. Observations of star-forming regions (young star clusters and HII regions) have shown evidence of a fractal pattern in their mass and luminosity distributions. The Mass Function (MF), and similarly the Luminosity Function (LF), of star-forming regions can be approximated as a power-law and is characterized by the power-law slope. A consistent slope of -2 has been observed across numerous galaxies, however, systematic deviations from this canonical slope have been measured across different environments. We present the LF slopes for 258 nearby galaxies in the Local Volume Legacy (LVL) sample utilizing tens of thousands of Hα- and FUV-selected sources. We test any relationships between LF slope and global galaxy properties to quantify the effect of environment on the star formation process. In addition, we combine the entire star-forming region sample in an attempt to characterize a previously proposed break in the HII region LF power-law at L˜38.6 erg/s.

  16. A Heuristic Prediction of the Cosmic Evolution of the Co-luminosity Functions

    NASA Astrophysics Data System (ADS)

    Obreschkow, D.; Heywood, I.; Klöckner, H.-R.; Rawlings, S.

    2009-09-01

    We predict the emission line luminosity functions (LFs) of the first 10 rotational transitions of 12C16O in galaxies at redshift z = 0 to z = 10. This prediction relies on a recently presented simulation of the molecular cold gas content in ~3 × 107 evolving galaxies based on the Millennium Simulation. We combine this simulation with a model for the conversion between molecular mass and CO-line intensities, which incorporates the following mechanisms: (1) molecular gas is heated by the cosmic microwave background (CMB), starbursts (SBs), and active galactic nuclei (AGNs); (2) molecular clouds in dense or inclined galaxies can overlap; (3) compact gas can attain a smooth distribution in the densest part of disks; (4) CO luminosities scale with metallicity changes between galaxies; and (5) CO luminosities are always detected against the CMB. We analyze the relative importance of these effects and predict the cosmic evolution of the CO-LFs. The most notable conclusion is that the detection of regular galaxies (i.e., no AGN, no massive SB) at high z gsim 7 in CO emission will be dramatically hindered by the weak contrast against the CMB, in contradiction to earlier claims that CMB heating will ease the detection of high-redshift CO. The full simulation of extragalactic CO lines and the predicted CO-LFs at any redshift can be accessed online (http://s-cubed.physics.ox.ac.uk/, go to "S3-SAX") and they should be useful for the modeling of CO-line surveys with future telescopes, such as the Atacama Large Millimeter/submillimeter Array or the Square Kilometre Array.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. The High-Redshift Quasar Luminosity Function from Multi-Epoch Imaging Surveys

    NASA Astrophysics Data System (ADS)

    AlSayyad, Yusra

    Upcoming time-domain imaging surveys such as the LSST will detect over a million high-redshift z > 4 quasars, making complete spectroscopic followup unfeasible. Statistical estimates such as luminosity functions and clustering measurements will require purely photometric methods for classifying quasars, estimating redshifts and estimating selection functions. We validate these methods and constrain the optical, type I quasar luminosity function (QLF) at 3.75 < z < 4.5 for -27.5 < M1450 3.75) and constraint on the characteristic luminosity (M*1450 = -26.7) from a single, uniformly-selected survey at z 4. We used the Sloan Digital Sky Survey (SDSS) repeated imaging of the 275 sq. deg. equatorial region of the sky (-50 < R.A. < +60; -1.26 < Dec. < +1.26), known as Stripe 82, to select a statistical sample of z 4 quasars. We extracted 40 million lightcurves from the imaging using forced photometry on all u, g, r, i, z epochs at the positions of sources detected on a deep i-band co-add. We developed a classification method based on photometric information alone (colors and variability metrics derived from these new multi-band lightcurves), which we validated with a spectroscopically complete 55 sq. deg. sub-region augmented with 102 new spectroscopic observations of quasars at z > 3.4 with i < 22.5. We demonstrate that selection functions for ensemble classifiers can be estimated by building generative models of empirical distributions of quasars previously selected with a diverse set of selection criteria. The z 4 QLF contributes to our understanding of supermassive black hole growth and cosmic reionization of both H I and He II which likely began at z 4 as a result of hard UV emissivity from quasars. The resulting QLF measurement is consistent with the previous lower number densities reported from deep, narrow-field surveys (COSMOS); it is not consistent with higher number densities reported from the NDWFS-DLS and CANDELS GOODS-S fields. In the context of recent 2

  19. MID-INFRARED DETERMINATION OF TOTAL INFRARED LUMINOSITY AND STAR FORMATION RATES OF LOCAL AND HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Rujopakarn, W.; Rieke, G. H.; Weiner, B. J.; Perez-Gonzalez, P.; Rex, M.; Walth, G. L.; Kartaltepe, J. S.

    2013-04-10

    We demonstrate estimating the total infrared luminosity, L(TIR), and star formation rates (SFRs) of star-forming galaxies at redshift 0 < z < 2.8 from single-band 24 {mu}m observations, using local spectral energy distribution (SED) templates without introducing additional free parameters. Our method is based on characterizing the SEDs of galaxies as a function of their L(TIR) surface density, which is motivated by the indications that the majority of IR luminous star-forming galaxies at 1 < z < 3 have extended star-forming regions, in contrast to the strongly nuclear concentrated, merger-induced starbursts in local luminous and ultraluminous IR galaxies. We validate our procedure for estimating L(TIR) by comparing the resulting L(TIR) with those measured from far-IR observations, such as those from Herschel in the Extended Chandra Deep Field South (ECDFS) and Hubble Deep Field North (HDFN), as well as L(TIR) measured from stacked far-IR observations at redshift 0 < z < 2.8. Active galactic nuclei were excluded using X-ray and 3.6-8.0 {mu}m observations, which are generally available in deep cosmological survey fields. The Gaussian fits to the distribution of the discrepancies between the L(TIR) measurements from single-band 24 {mu}m and Herschel observations in the ECDFS and HDFN samples have {sigma} < 0.1 dex, with {approx}10% of objects disagreeing by more than 0.2 dex. Since the 24 {mu}m estimates are based on SEDs for extended galaxies, this agreement suggests that {approx}90% of IR galaxies at high z are indeed much more physically extended than local counterparts of similar L(TIR), consistent with recent independent studies of the fractions of galaxies forming stars in the main-sequence and starburst modes, respectively. Because we have not introduced empirical corrections to enhance these estimates, in principle, our method should be applicable to lower luminosity galaxies. This will enable use of the 21 {mu}m band of the Mid-Infrared Instrument on board

  20. THE FAINT END OF THE LUMINOSITY FUNCTION AND LOW SURFACE BRIGHTNESS GALAXIES

    SciTech Connect

    Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G.; Diaferio, Antonaldo; Dell'Antonio, Ian P. E-mail: mkurtz@cfa.harvard.edu E-mail: adiaferio@cfa.harvard.edu

    2012-04-15

    Smithsonian Hectospec Lensing Survey (SHELS) is a dense redshift survey covering a 4 deg{sup 2} region to a limiting R = 20.6. In the construction of the galaxy catalog and in the acquisition of spectroscopic targets, we paid careful attention to the survey completeness for lower surface brightness dwarf galaxies. Thus, although the survey covers a small area, it is a robust basis for computation of the slope of the faint end of the galaxy luminosity function to a limiting M{sub R} = -13.3 + 5log h. We calculate the faint-end slope in the R band for the subset of SHELS galaxies with redshifts in the range 0.02 {<=}z < 0.1, SHELS{sub 0.1}. This sample contains 532 galaxies with R < 20.6 and with a median surface brightness within the half-light radius of SB{sub 50,R} = 21.82 mag arcsec{sup -2}. We used this sample to make one of the few direct measurements of the dependence of the faint end of the galaxy luminosity function on surface brightness. For the sample as a whole the faint-end slope, {alpha} = -1.31 {+-} 0.04, is consistent with both the Blanton et al. analysis of the Sloan Digital Sky Survey and the Liu et al. analysis of the COSMOS field. This consistency is impressive given the very different approaches of these three surveys. A magnitude-limited sample of 135 galaxies with optical spectroscopic redshifts with mean half-light surface brightness, SB{sub 50,R} {>=} 22.5 mag arcsec{sup -2} is unique to SHELS{sub 0.1}. The faint-end slope is {alpha}{sub 22.5} = -1.52 {+-} 0.16. SHELS{sub 0.1} shows that lower surface brightness objects dominate the faint-end slope of the luminosity function in the field, underscoring the importance of surface brightness limits in evaluating measurements of the faint-end slope and its evolution.

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    We provide fits to the distribution of galaxy luminosity, size, velocity dispersion and stellar mass as a function of concentration index Cr and morphological type in the Sloan Digital Sky Survey (SDSS). (Our size estimate, a simple analogue of the SDSS cmodel magnitude, is new: it is computed using a combination of seeing-corrected quantities in the SDSS data base, and is in substantially better agreement with results from more detailed bulge/disc decompositions.) We also quantify how estimates of the fraction of `early'- or `late'-type galaxies depend on whether the samples were cut in colour, concentration or light profile shape, and compare with similar estimates based on morphology. Our fits show that ellipticals account for about 20 per cent of the r-band luminosity density, , and 25 per cent of the stellar mass density, ρ* including S0s and Sas increases these numbers to 33 per cent and 40 per cent, and 50 per cent and 60 per cent, respectively. The values of and ρ*, and the mean sizes, of E, E+S0 and E+S0+Sa samples are within 10 per cent of those in the Hyde & Bernardi, Cr >= 2.86 and Cr >= 2.6 samples, respectively. Summed over all galaxy types, we find ρ* ~ 3 × 108MsolarMpc-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 × 1011Msolar. The stellar mass density further increases at large masses if we assume different initial mass functions for elliptical and spiral galaxies, as suggested by some recent chemical evolution models, and results in a better agreement with the dynamical mass function. We also show that the trend for ellipticity to decrease with luminosity is primarily because the E/S0 ratio increases at large L. However, the most massive galaxies, M* >= 5 × 1011Msolar, are less concentrated and not as round as expected if one extrapolates from lower L, and they are

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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 < z < 0.3 and LX ≈ 2 × 1043 erg s-1 compared with the reference low-redshift XLF, or our Bayesian fit to the 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.

  4. The readout of the LHC beam luminosity monitor: Accurate shower energy measurements at a 40 MHz repetition rate

    SciTech Connect

    Manfredi, P.F.; Ratti, L.; Speziali, V.; Traversi, G.; Manghisoni, M.; Re, V.; Denes, P.; Placidi, M.; Ratti, A.; Turner, W.C.; Datte, P.S.; Millaud, J.E.

    2003-05-10

    The LHC beam luminosity monitor is based on the following principle. The neutrals that originate in LHC at every PP interaction create showers in the absorbers placed in front of the cryogenic separation dipoles. The shower energy, as it can be measured by suitable detectors in the absorbers is proportional to the number of neutral particles and, therefore, to the luminosity. This principle lends itself to a luminosity measurement on a bunch-by-bunch basis. However, detector and front-end electronics must comply with extremely stringent requirements. To make the bunch-by-bunch measurement feasible, their speed of operation must match the 40 MHz bunch repetition rate of LHC. Besides, in the actual operation the detector must stand extremely high radiation doses. The front-end electronics, to survive, must be located at some distance from the region of high radiation field, which means that a properly terminated, low-noise, cable connection is needed between detector and front-end electronics. After briefly reviewing the solutions that have been adopted for the detector and the front-end electronics and the results that have been obtained so far in tests on the beam, the latest version of the instrument in describe in detail. It will be shown how a clever detector design, a suitable front-end conception based on the use of a ''cold resistance'' cable termination and a careful low-noise design, along with the use of an effective deconvolution algorithm, make the luminosity measurement possible on a bunch-by-bunch basis at the LHC bunch repetition rates.

  5. Characterizing the Properties of Clusters of Galaxies As a Function of Luminosity and Redshift

    SciTech Connect

    Andersson, K.; Peterson, J.R.; Madejski, G.; Goobar, A.; /Stockholm U. /Stockholm U., OKC

    2009-02-24

    We report the application of the new Monte Carlo method, Smoothed Particle Inference (SPI, described in a pair of companion papers), towards analysis and interpretation of X-ray observations of clusters of galaxies with the XMM-Newton satellite. Our sample consists of publicly available well-exposed observations of clusters at redshifts z > 0.069, totaling 101 objects. We determine the luminosity and temperature structure of the X-ray emitting gas, with the goal to quantify the scatter and the evolution of the L{sub X} - T relation, as well as to investigate the dependence on cluster substructure with redshift. This work is important for the establishment of the potential robustness of mass estimates from X-ray data which in turn is essential towards the use of clusters for measurements of cosmological parameters. We use the luminosity and temperature maps derived via the SPI technique to determine the presence of cooling cores, via measurements of luminosity and temperature contrast. The L{sub X}-T relation is investigated, and we confirm that L{sub X} {proportional_to} T{sup 3}. We find a weak redshift dependence ({proportional_to} (1 + z){sup {beta}{sub LT}}, {beta}{sub LT} = 0.50 {+-} 0.34), in contrast to some Chandra results. The level of dynamical activity is established using the 'power ratios' method, and we compare our results to previous application of this method to Chandra data for clusters. We find signs of evolution in the P{sub 3}/P{sub 0} power ratio. A new method, the 'temperature two-point correlation function', is proposed. This method is used to determine the 'power spectrum' of temperature fluctuations in the X-ray emitting gas as a function of spatial scale. We show how this method can be fruitfully used to identify cooling core clusters as well as those with disturbed structures, presumably due to on-going or recent merger activity.

  6. The Radio luminosity Function of Radio-Loud Quasars from the 7C Redshift Survey

    NASA Technical Reports Server (NTRS)

    Willott, Chris J.; Rawlings, Steve; Blundell, Katherine M.; Lacy, Mark

    1998-01-01

    We present a complete sample of 24 radio-loud quasars (RLQs) from the new 7C Redshift Survey. Every quasar with a low-frequency (151 MHz) radio flux-density S(sub 151) > 0.5 Jy in two regions of the sky covering 0.013 sr is included; 23 of these have sufficient extended flux to meet the selection criteria, 18 of these have steep radio spectra (hereafter denoted as SSQs). The key advantage of this sample over most samples of RLQs is the lack of an optical magnitude limit. By combining the 7C and 3CRR samples, we have investigated the properties of RLQs as a function of redshift z and radio luminosity L(sub 151). We derive the radio luminosity function (RLF) of RLQs and find that the data are well fitted by a single power-law with slope alpha(sub 1) = 1.9 +/- 0.1 (for H(sub 0) = 50 km/s.Mpc, OMEGA(sub M) = 1, OMEGA(sub DELTA) = 0). We find that there must be a break in the RLQ RLF at log(sub 10)(L(sub 151)/W Hz.sr) approximately < or = 27, in order for the models to be consistent with the 7C and 6C source counts. The z-dependence of the RLF follows a one-tailed gaussian which peaks at z = 1.7 +/- 0.2. We find no evidence for a decline in the co-moving space density of RLQs at higher redshifts. A positive correlation between the radio and optical luminosities of SSQs is observed, confirming a result of Serjeant. We are able to rule out this correlation being due to selection effects or biases in our combined sample. The radio-optical correlation and best-fit model RLF enable us to estimate the distribution of optical magnitudes of quasars in samples selected at low radio frequencies, We con- clude that for samples with S(sub 151) approximately < or = 1 Jy one must use optical data significantly deeper than the POSS-I limit (R approximately equal 20), in order to avoid severe incompleteness.

  7. The extended Baryon Oscillation Spectroscopic Survey: Variability selection and quasar luminosity function

    NASA Astrophysics Data System (ADS)

    Palanque-Delabrouille, N.; Magneville, Ch.; Yèche, Ch.; Pâris, I.; Petitjean, P.; Burtin, E.; Dawson, K.; McGreer, I.; Myers, A. D.; Rossi, G.; Schlegel, D.; Schneider, D.; Streblyanska, A.; Tinker, J.

    2016-03-01

    The extended Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey (SDSS-IV/eBOSS) has an extensive quasar program that combines several selection methods. Among these, the photometric variability technique provides highly uniform samples, which are unaffected by the redshift bias of traditional optical-color selections, when z = 2.7-3.5 quasars cross the stellar locus or when host galaxy light affects quasar colors at z< 0.9. We present the variability selection of quasars in eBOSS, focusing on a specific program that led to a sample of 13 876 quasars to gdered = 22.5 over a 94.5 deg2 region in Stripe 82, which has an areal density 1.5 times higher than over the rest of the eBOSS footprint. We use these variability-selected data to provide a new measurement of the quasar luminosity function (QLF) in the redshift range of 0.68 luminosity-function evolution (PLE) with bright-end and faint-end slopes allowed to be different on either side of z = 2.2. The other is a simple PLE at z< 2.2, combined with a model that comprises both luminosity and density evolution (LEDE) at z> 2.2. Both models are constrained to be continuous at z = 2.2. They present a flattening of the bright-end slope at high redshift. The LEDE model indicates a reduction of the break density with increasing redshift, but the evolution of the break magnitude depends on the parameterization. The models are in excellent accord, predicting quasar counts that agree within 0.3% (resp., 1.1%) to g< 22.5 (resp., g< 23). The models are also in good agreement over the entire redshift range with models from previous studies.

  8. The Radio and IR Luminosity Function of compact Galactic HII regions

    NASA Astrophysics Data System (ADS)

    Paladini, R.; De Zotti, G.; Noriega-Crespo, A.; Carey, S. J.

    2009-01-01

    We present the radio luminosity function (LF) of compact Galactic HII regions, derived by using ˜ 200 sources from the recombination line survey by Caswell & Haynes (1987). The data set is complete for Speak > 1.3 Jy at 5 GHz, corresponding to an integrated flux density of ˜ 3 Jy. The LF is reconstructed by means of a generalized Schmidt's estimator which takes into account the actual spatial distribution of the HII regions along the plane of the Galaxy. The resulting LF is described by a two-component power-law, with a cut-off at log L(α) = ˜ 38.3 erg/sec. This work will be complemented with the derivation, by means of the MIPSGAL data set, of the IR counterpart of the radio LF here presented. An extension of this work will consist in deriving the IR counterpart of the radio LF here obtained, by making use of the MIPSGAL data set.

  9. Constraining Neutrino Cooling Using the Hot White Dwarf Luminosity Function in the Globular Cluster 47 Tucanae

    NASA Astrophysics Data System (ADS)

    Hansen, Brad M. S.; Richer, Harvey; Kalirai, Jason; Goldsbury, Ryan; Frewen, Shane; Heyl, Jeremy

    2015-08-01

    We present Hubble Space Telescope observations of the upper part ({T}{eff}\\gt {10}4 K) of the white dwarf cooling sequence in the globular cluster 47 Tucanae and measure a luminosity function of hot white dwarfs. Comparison with previous determinations from large-scale field surveys indicates that the previously determined plateau at high effective temperatures is likely a selection effect, as no such feature is seen in this sample. Comparison with theoretical models suggests that the current estimates of white dwarf neutrino emission (primarily by the plasmon channel) are accurate, and variations are restricted to no more than a factor of two globally, at 95% confidence. We use these constraints to place limits on various proposed exotic emission mechanisms, including a nonzero neutrino magnetic moment, formation of axions, and emission of Kaluza-Klein modes into extra dimensions.

  10. Models of stellar population at high redshift, as constrainedby PN yields and luminosity function

    NASA Astrophysics Data System (ADS)

    Maraston, C.

    The stellar phase of Thermally-Pulsating Asymptotic giant branch is the last major evolutionary stage of intermediate-mass stars which afterwards evolve into planetary nebulae. The TP-AGB phase is affected by mass-loss and instabilities which notoriously make its theoretical modelling uncertain. This review focuses on the effects such modelling has on stellar population models for galaxies, with particular focus on the high-z Universe where galaxies are young and contain a large number of short-living TP-AGB stars. I shall present the models, discuss how different prescriptions for the treatment of the TP-AGB affect the theoretical integrated spectral energy distribution and how these compare to galaxy data, and discuss implications for the PN nebulae luminosity function stemming from the various assumptions. Finally I shall discuss the inclusion of hot evolved stars on stellar population models and how they compare to data for old galaxies at our present time.

  11. Keck Deep Fields. III. Luminosity-dependent Evolution of the Ultraviolet Luminosity and Star Formation Rate Densities at z~4, 3, and 2

    NASA Astrophysics Data System (ADS)

    Sawicki, Marcin; Thompson, David

    2006-09-01

    We use our very deep UnGRI catalog of z~4, 3, and 2 UV-selected star-forming galaxies to study the cosmological evolution of the rest-frame 1700 Å luminosity density. The ability to reliably constrain the contribution of faint galaxies is critical here, and our data do so by reaching deep into the galaxy population, to M*LBG+2 at z~4 and deeper still at lower redshifts (M*LBG=-21.0 and L*LBG is the corresponding luminosity). We find that the luminosity density at z>~2 is dominated by the hitherto poorly studied galaxies fainter than L*LBG, and, indeed, the bulk of the UV light at these epochs comes from galaxies in the rather narrow luminosity range L=(0.1-1)L*LBG. Overall, there is a gradual rise in total luminosity density starting at >~4 (we find twice as much UV light at z~3 as at z~4), followed by a shallow peak or plateau within z~3-1, finally followed by the well-known plunge to z~0. Within this total picture, luminosity density in sub-L*LBG galaxies at z>~2 evolves more rapidly than that in more luminous objects; this trend is reversed at lower redshifts, z<~1-a reversal that is reminiscent of galaxy downsizing. We find that within the context of commonly used models there seemingly are not enough faint or bright LBGs to maintain ionization of intergalactic gas even as recently as z~4, and the problem becomes worse at higher redshifts: apparently the universe must be easier to reionize than some recent studies have assumed. Nevertheless, sub-L*LBG galaxies do dominate the total UV luminosity density at z>~2, and this dominance highlights the need for follow-up studies that will teach us more about these very numerous but thus far largely unexplored systems. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA and was made possible by the generous financial support of the W. M. Keck Foundation.

  12. A new psychophysical method for determining the photopic spectral-luminosity function of the human eye.

    PubMed

    Rovamo, J; Koljonen, T; Näsänen, R

    1996-09-01

    Using an 8 mm pupil, 2AFC-method, and 2 x 2 deg2 grating at 2 c/deg we measured contrast sensitivity as a function of integrated radiance for a series of interference filters with peak wavelengths at 400-700 nm. Irrespective of the radiance level, contrast sensitivity was highest when wavelength was at and around 550 nm. It decreased towards longer and shorter wavelengths, reflecting the variation of the probability of quantal catch with light wavelength. When contrast sensitivity functions plotted in double logarithmic coordinates were shifted horizontally by multiplying the integrated radiances of each filter by an appropriate scaling factor, the functions superimposed onto a single curve. Contrast sensitivity at lower levels of relative radiance (R) increased in proportion to square root of R, obeying DeVries-Rose law, but at higher levels contrast sensitivity was constant, obeying Weber's law. Scaling factors plotted as a function of wavelength provided an estimate of V(lambda) quite similar to the standard 2 deg photopic spectral-luminosity function of CIE 1924.

  13. Black holes, disks, and jets following binary mergers and stellar collapse: The narrow range of electromagnetic luminosities and accretion rates

    NASA Astrophysics Data System (ADS)

    Shapiro, Stuart L.

    2017-05-01

    We have performed magnetohydrodynamic simulations in general relativity of binary neutron star and binary black hole-neutron star mergers, as well as the magnetorotational collapse of supermassive stars. In many cases the outcome is a spinnng black hole (BH) immersed in a magnetized disk, with a jet emanating from the poles of the BH. While their formation scenarios differ and their BH masses, as well as their disk masses, densities, and magnetic field strengths, vary by orders of magnitude, these features conspire to generate jet Poynting luminosities that all lie in the same, narrow range of ˜1 052 ±1 erg s-1 . A similar result applies to their BH accretion rates upon jet launch, which is ˜0.1 - 10 M⊙ s-1 . We provide a simple model that explains these unanticipated findings. Interestingly, these luminosities reside in the same narrow range characterizing the observed luminosity distributions of over 400 short and long GRBs with distances inferred from spectroscopic redshifts or host galaxies. This result, together with the GRB lifetimes predicted by the model, supports the belief that a compact binary merger is the progenitor of an SGRB, while a massive, stellar magnetorotational collapse is the progenitor of an LGRB.

  14. The role of cluster mergers and travelling shocks in shaping the Hα luminosity function at z ˜ 0.2: `sausage' and `toothbrush' clusters

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David; Röttgering, Huub J. A.; van Weeren, Reinout J.

    2014-02-01

    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 ˜ 0.2) host enormous radio-emitting shocks with simple geometry. We investigate the role of mergers and shocks in shaping the Hα luminosity function, using custom-made narrow-band filters matching the cluster redshifts mounted on the Isaac Newton Telescope. We surveyed ˜0.28 deg2 for each cluster and found 181 line emitters in the `sausage' (volume of 3.371 × 103 Mpc3 for Hα at z = 0.1945) and 141 in the `toothbrush' (4.546 × 103 Mpc3 for Hα at z = 0.225), out of which 49 (`sausage') and 30 (`toothbrush') are expected to be Hα. We build luminosity functions for the field-of-view down to an average limiting star formation rate of 0.14 M⊙ yr-1, find good agreement with field luminosity functions at z = 0.2, but significant differences between the shapes of the luminosity functions for the two clusters. We discover extended, tens-of-kpc-wide Hα haloes in galaxies neighbouring relics, which were possibly disrupted by the passage of the shock wave. By comparing the `sausage' cluster with blank fields and other clusters, we also uncover an order of magnitude boost (at 9σ level) in the normalization φ* of the luminosity function in the relic areas. Our results suggest that cluster mergers may play an important role in the evolution of cluster galaxies through shock-induced star formation.

  15. The local stellar luminosity function and mass-to-light ratio in the near-infrared

    NASA Astrophysics Data System (ADS)

    Just, A.; Fuchs, B.; Jahreiß, H.; Flynn, C.; Dettbarn, C.; Rybizki, J.

    2015-07-01

    A new sample of stars, representative of the solar neighbourhood luminosity function (LF), is constructed from the Hipparcos catalogue and the Fifth Catalogue of Nearby Stars. We have cross-matched to sources in the Two Micron All Sky Survey catalogue so that for all stars individually determined near-infrared (NIR) photometry is available on a homogeneous system (typically Ks). The spatial completeness of the sample has been carefully determined by statistical methods, and the NIR LF of the stars has been derived by direct star counts. We find a local volume luminosity of 0.121 ± 0.004 LK⊙ pc-3, corresponding to a volumetric mass-to-light ratio (M/L) of M/L_K = 0.31 ± 0.02 {M}_{⊙}/L_{K⊙}, where giants contribute 80 per cent to the light but less than 2 per cent to the stellar mass. We derive the surface brightness of the solar cylinder with the help of a vertical disc model. We find a surface brightness of 99 LK⊙ pc-2 with an uncertainty of approximately 10 per cent. This corresponds to an M/L for the solar cylinder of M/L_K = 0.34 {M}_{⊙}/L_{K⊙}. The M/L for the solar cylinder is only 10 per cent larger than the local value despite the fact that the local population has a much larger contribution of young stars. It turns out that the effective scaleheights of the lower main sequence carrying most of the mass is similar to that of the giants, which are dominating the NIR light. The corresponding colour for the solar cylinder is V - K = 2.89 mag compared to the local value of V - K = 2.46 mag. An extrapolation of the local surface brightness to the whole Milky Way yields a total luminosity of MK = -24.2 mag. The Milky Way falls in the range of K band Tully-Fisher relations from the literature.

  16. CONSTRAINTS ON THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z {approx} 5 IN THE COSMOS FIELD

    SciTech Connect

    Ikeda, H.; Matsuoka, K.; Kajisawa, M.; Nagao, T.; Taniguchi, Y.; Shioya, Y.; Enoki, M.; Capak, P.; Masters, D.; Scoville, N. Z.; Civano, F.; Koekemoer, A. M.; Morokuma, T.; Salvato, M.; Schinnerer, E.

    2012-09-10

    We present the result of our low-luminosity quasar survey in the redshift range of 4.5 {approx}< z {approx}< 5.5 in the COSMOS field. Using the COSMOS photometric catalog, we selected 15 quasar candidates with 22 < i' < 24 at z {approx} 5 that are {approx}3 mag fainter than the Sloan Digital Sky Survey quasars in the same redshift range. We obtained optical spectra for 14 of the 15 candidates using FOCAS on the Subaru Telescope and did not identify any low-luminosity type-1 quasars at z {approx} 5, while a low-luminosity type-2 quasar at z {approx} 5.07 was discovered. In order to constrain the faint end of the quasar luminosity function at z {approx} 5, we calculated the 1{sigma} confidence upper limits of the space density of type-1 quasars. As a result, the 1{sigma} confidence upper limits on the quasar space density are {Phi} < 1.33 Multiplication-Sign 10{sup -7} Mpc{sup -3} mag{sup -1} for -24.52 < M{sub 1450} < -23.52 and {Phi} < 2.88 Multiplication-Sign 10{sup -7} Mpc{sup -3} mag{sup -1} for -23.52 < M{sub 1450} < -22.52. The inferred 1{sigma} confidence upper limits of the space density are then used to provide constraints on the faint-end slope and the break absolute magnitude of the quasar luminosity function at z {approx} 5. We find that the quasar space density decreases gradually as a function of redshift at low luminosity (M{sub 1450} {approx} -23), being similar to the trend found for quasars with high luminosity (M{sub 1450} < -26). This result is consistent with the so-called downsizing evolution of quasars seen at lower redshifts.

  17. Statistics and properties of H II regions in a sample of grand design galaxies I. Luminosity functions.

    NASA Astrophysics Data System (ADS)

    Rozas, M.; Beckman, J. E.; Knapen, J. H.

    1996-03-01

    We present new high quality continuum-subtracted Hα images of the grand-design galaxies NGC 157, NGC 3631, NGC 6764 and NGC 6951. We have determined the positions, angular sizes, and fluxes of their individual HII regions, and describe statistical properties of the HII region samples. We construct luminosity functions for all the HII regions in the disc and separately for arm and interarm zones for each galaxy. The slopes of the luminosity functions for the complete sample agree well with values published for other spiral galaxies of comparable morphological type. For three galaxies we determined the slopes of the luminosity functions for the spiral arm and interarm zones separately. We find that for NGC 157, NGC 3631, and NGC 6951 these slopes are equal within the errors of determination. We compare our results to those found from earlier work, specifically for M51 and NGC 6814, and discuss implications for massive star forming processes.

  18. The rest-frame K-band luminosity function of galaxies in clusters to z = 1.3

    SciTech Connect

    De Propris, R; Stanford, S A; Eisenhardt, P R; Holden, B P; Rosati, P

    2007-03-20

    We derive the rest-frame K-band luminosity function for galaxies in 32 clusters at 0.6 < z < 1.3 using deep 3.6 {micro}m and 4.5 {micro}m imaging from the Spitzer Space Telescope InfraRed Array Camera (IRAC). The luminosity functions approximate the stellar mass function of the cluster galaxies. Their dependence on redshift indicates that massive cluster galaxies (to the characteristic luminosity M*{sub K}) are fully assembled at least at z {approx} 1.3 and that little significant accretion takes place at later times. The existence of massive, highly evolved galaxies at these epochs is likely to represent a significant challenge to theories of hierarchical structure formation where such objects are formed by the late accretion of spheroidal systems at z < 1.

  19. PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES

    SciTech Connect

    He, Y. Q.; Xia, X. Y.; Hao, C. N.; Jing, Y. P.; Mao, S.; Li, Cheng

    2013-08-10

    We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (M{sub r} < -22.5 mag) in the redshift range of 0.05-0.15, drawn from the Sloan Digital Sky Survey (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 for the brightest galaxies (M{sub r} < -23 mag), our Petrosian magnitudes and isophotal magnitudes to 25 mag arcsec{sup -2} and 1% of the sky brightness are on average 0.16 mag, 0.20 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. Similarly, the typical half-light radii (r{sub 50}) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M{sub *} {approx} 5 Multiplication-Sign 10{sup 11} M{sub Sun} and M{sub *} {approx} 10{sup 12} M{sub Sun} are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.

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

    SciTech Connect

    Mancone, Conor L.; Baker, Troy; Gonzalez, Anthony H.; Ashby, Matthew L. N.; Snyder, Greg; Stanford, Spencer A.; Brodwin, Mark; Eisenhardt, Peter R. M.; Stern, Daniel; Wright, Edward L.

    2012-12-20

    We measure the faint-end slope of the galaxy luminosity function (LF) for cluster galaxies at 1 < z < 1.5 using Spitzer IRAC data. We investigate whether this slope, {alpha}, differs from that of the field LF at these redshifts, and with the cluster LF at low redshifts. The latter is of particular interest as low-luminosity galaxies are expected to undergo significant evolution. We use seven high-redshift spectroscopically confirmed galaxy clusters drawn from the IRAC Shallow Cluster Survey to measure the cluster-galaxy LF down to depths of M* + 3 (3.6 {mu}m) and M* + 2.5 (4.5 {mu}m). The summed LF at our median cluster redshift (z = 1.35) is well fit by a Schechter distribution with {alpha}{sub 3.6{mu}m} = -0.97 {+-} 0.14 and {alpha}{sub 4.5{mu}m} = -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 {alpha} 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 {approx} 1.3, this means that the shape of the cluster LF is largely in place by z {approx} 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 {approx}< 1.3.

  1. The SDSS u-band Galaxy Survey: Luminosity functions and evolution

    SciTech Connect

    Baldry, Ivan K.; Glazebrook, K.; Budavari, T.; Eisenstein, D.J.; Annis, J.; Bahcall, N.A.; Blanton, M.R.; Brinkmann, J.; Csabai, I.; Heckman, T.M.; Lin, H.; Loveday, J.; Nichol, R.C.; Schneider, D.P.; /Johns Hopkins U. /Arizona U., Astron. Dept. - Steward Observ. /Fermilab /Princeton U. /CCPP, New York /Apache Point Observ. /Eotvos U. /Sussex U., Astron. Ctr. /Portsmouth U., ICG /Penn State U., Astron. Astrophys.

    2005-01-01

    We construct and analyze a u-band selected galaxy sample from the SDSS Southern Survey, which covers 275 deg{sup 2}. The sample includes 43223 galaxies with spectroscopic redshifts in the range 0.005 < z < 0.3 and with 14.5 < u < 20.5. The S/N in the u-band Petrosian aperture is improved by coadding multiple epochs of imaging data and by including sky-subtraction corrections. Luminosity functions for the near-UV {sup 0.1}u band ({lambda} {approx} 322 {+-} 26 nm) are determined in redshift slices of width 0.02, which show a highly significant evolution in M* of -0.8 {+-} 0.1 mag between z = 0 and 0.3; with M* - 5 log h{sub 70} = -18.84 {+-} 0.05 (AB mag), log {phi}* = -2.06 {+-} 0.03 (h{sub 70}{sup 3} Mpc{sup -3}) and log {rho}{sub L} = 19.11 {+-} 0.02 (h{sub 70} W Hz{sup -1}Mpc{sup -3}) at z = 0.1. The faint-end slope determined for z < 0.06 is given by {alpha} = -1.05 {+-} 0.08. This is in agreement with recent determinations from GALEX at shorter wavelengths. Comparing our z < 0.3 luminosity density measurements with 0.2 < z < 1.2 from COMBO-17, we find that the 280-nm density evolves as {rho}{sub L} {proportional_to} (1+z){sup {beta}} with {beta} = 2.1 {+-} 0.2; and find no evidence for any change in slope over this redshift range. By comparing with other measurements of cosmic star formation history, we estimate that the effective dust attenuation at 280 nm has increased by 0.8 {+-} 0.3 mag between z = 0 and 1.

  2. X-ray selected quasars and Seyfert galaxies - Cosmological evolution, luminosity function, and contribution to the X-ray background

    NASA Technical Reports Server (NTRS)

    Maccacaro, T.; Gioia, I. M.; Stocke, J. T.

    1984-01-01

    The cosmological evolution and the X-ray luminosity function of quasars and Seyfert galaxies (active galactic nuclei /AGNs/) are derived and discussed. The sample used consists of 56 objects extracted from the expanded Einstein Observatory Medium Sensitivity Survey, and it is exclusively defined by its X-ray properties. The distribution in space of X-ray selected AGNs is confirmed to be strongly nonuniform; the amount of cosmological evolution required by the data is in agreement with a previous determination based on a smaller sample of objects. The X-ray luminosity function (XLF) is derived. The high-luminosity part of the XLF is satisfactorily described by a power law of slope gamma approximately 3.6. A significant flattening is observed at low luminosities. The simultaneous determination of the cosmological evolution and of the X-ray luminosity function of AGNs is then used to estimate the contribution to the extragalactic diffuse X-ray background. Using the best fit values for the evolution of AGNs and for their volume density, it is found that they contribute approximately 80 percent of the 2 keV diffuse X-ray background. Uncertainties in this estimate are still rather large; however, it seems difficult to reconcile the data with a contribution much less than 50 percent.

  3. Optical spectroscopy and the UV luminosity function of galaxies in the Abell 1367, Coma and Virgo clusters

    NASA Astrophysics Data System (ADS)

    Cortese, L.; Gavazzi, G.; Iglesias-Paramo, J.; Boselli, A.; Carrasco, L.

    2003-04-01

    Optical spectroscopy of 93 galaxies, 60 projected in the direction of Abell 1367, 21 onto the Coma cluster and 12 on Virgo, is reported. The targets were selected because they were detected in previous Hα , UV or r' surveys. The present observations bring to 100% the redshift completeness of Hα selected galaxies in the Coma region and to 75% in Abell 1367. All observed galaxies except one show Hα emission and belong to the clusters. This confirms previous determinations of the Hα luminosity function of the two clusters that were based on the assumption that all Hα detected galaxies were cluster members. Using the newly obtained data we re-determine the UV luminosity function of Coma and we compute for the first time the UV luminosity function of A1367. Their faint end slopes remain uncertain (-2.00luminosity function will be alpha ~ -1.35, in agreement with the UV luminosity function of the field (Sullivan et al. \\cite{Sullivan}) and with the Hα luminosity functions of the two clusters (Iglesias-Paramo et al. \\cite{lha}). We discover a point-like Hα source in the Virgo cluster, associated with the giant galaxy VCC873, possibly an extragalactic HII region similar to the one recently observed in Virgo by Gerhard et al. (\\cite{Gerhard}). Based on observations obtained with the Loiano telescope belonging to the University of Bologna (Italy), with the G. Haro telescope of the INAOE (Mexico) and with the Calar Alto observatory operated by the Centro Astronomico Hispano Aleman (Spain).

  4. Optical Variability of Quasars as a Function of Luminosity and Redshift

    NASA Astrophysics Data System (ADS)

    Gaskell, C. M.; Koratkar, A. P.; Kwon, T.-Y.; Liang, Y.; Scott, J. H.; Wysota, A.

    1987-09-01

    Various models of the "central engine" in quasars make different predictions of how the degree of variability and its timescale vary with luminosity. In the past there have been conflicting claims about the luminosity and redshift dependence of quasar variability. We have examined the photographic light curves obtained at the Rosemary Hill Observatory (U. of Florida) and the Royal Greenwich Observatory (Herstmonceux) for over a hundred quasars (both radio-loud and radio-quiet). We demonstrate how the previously-reported redshift dependence is a consequence of time dilation, and find that, after allowance for this, there is no luminosity dependence in the amplitude of variability. High-luminosity quasars are not less variable than their low-luminosity counterparts. This creates major difficulties for some classes of quasar model with discrete accretion events (e.g., gas cloud or disrupted stars being "swallowed" directly).

  5. The luminosity function of galactic X-ray sources - A cutoff and a 'standard candle'

    NASA Technical Reports Server (NTRS)

    Margon, B.; Ostriker, J. P.

    1973-01-01

    Analysis of the 2- to 10-kev luminosity distribution of 36 X-ray sources in the Local Group having known or estimated distances, showing that there exists a luminosity cutoff of approximately 10 to the 37.7th ergs/sec in agreement with the theoretical (Eddington) limit for the luminosity of an approximately 1 solar mass star. Furthermore, among the complete sample of high-luminosity sources, there appears to be a statistically significant group of X-ray 'standard candles' at (within less than 0.8 mag) the critical luminosity. This finding (which is in agreement with the self-consistent mass flow accretion models) presents the possibility that X-ray sources may be used as extragalactic distance indicators in the next generation of X-ray astronomy experiments.

  6. Characterizing the evolving K -band luminosity function using the UltraVISTA, CANDELS and HUDF surveys

    NASA Astrophysics Data System (ADS)

    Mortlock, Alice; McLure, Ross J.; Bowler, Rebecca A. A.; McLeod, Derek J.; Mármol-Queraltó, Esther; Parsa, Shaghayegh; Dunlop, James S.; Bruce, Victoria A.

    2017-02-01

    We present the results of a new study of the K-band galaxy luminosity function (KLF) at redshifts z ≤ 3.75, based on a nested combination of the UltraVISTA, Cosmic Assembly Near-infrared Deep Legacy Extragalactic Survey and HUDF surveys. The large dynamic range in luminosity spanned by this new data set (3-4 dex over the full redshift range) is sufficient to clearly demonstrate for the first time that the faint-end slope of the KLF at z ≥ 0.25 is relatively steep (-1.3 ≤ α ≤ -1.5 for a single Schechter function), in good agreement with recent theoretical and phenomenological models. Moreover, based on our new data set, we find that a double Schechter function provides a significantly improved description of the KLF at z ≤ 2. At redshifts z ≥ 0.25, the evolution of the KLF is remarkably smooth, with little or no evolution evident at faint (MK ≥ -20.5) or bright magnitudes (MK ≤ -24.5). Instead, the KLF is seen to evolve rapidly at intermediate magnitudes, with the number density of galaxies at MK ≃-23 dropping by a factor of ≃5 over the redshift interval 0.25 ≤ z ≤ 3.75. Motivated by this, we explore a simple description of the evolving KLF based on a double Schechter function with fixed faint-end slopes (α1 = -0.5, α2 = -1.5) and a shared characteristic magnitude (MK^{star }). According to this parametrization, the normalization of the component which dominates the faint end of the KLF remains approximately constant, with φ ^{star }2 decreasing by only a factor of ≃2 between z ≃0 and 3.25. In contrast, the component which dominates the bright end of the KLF at low redshifts evolves dramatically, becoming essentially negligible by z ≃3. Finally, we note that within this parametrization, the observed evolution of MK^{star } between z ≃0 and 3.25 is entirely consistent with MK^{star } corresponding to a constant stellar mass of M⋆ ≃5 × 1010 M⊙ at all redshifts.

  7. Exploring the Quasar Luminosity Function with Quasars Selected by both Color and Variability

    NASA Astrophysics Data System (ADS)

    Peters, Christina M.; Richards, Gordon T.

    2016-01-01

    Using a Bayesian selection algorithm, we determine the optimal combination of color and variability information to identify quasars in current and future multi-epoch optical surveys. The color analysis is based on SDSS photometry, and the variability parameters are calculated from power-law fits to the structure functions. Simultaneous color and variability classification improves classification over either color or variability selection alone, with particular improvement in the selection of quasars with colors similar to stars. This method identifies 22,867 new type 1 quasar candidates in SDSS Stripe 82, which can be combined with the WISE and SDSS photometric quasar candidate catalogs. The redshifts of the candidate quasars were estimated using all available bands, weighting each band by smoothing the PDF. We show how to correct the candidate quasar luminosity function (QLF) for the completeness fraction and systematic errors in redshifts. The corrected QLF is comparable to those determined by spectroscopic investigations, suggesting that LSST and other next-generation surveys will be able to accurately determine the QLF in the absence of spectra. Finally, the quasars are divided into high and low Eddington fractions, using delta(g-i) and CIV blueshift as proxies. The candidate QLFs for the two populations are compared to look for changes as a function of redshift. This work was supported in part by NSF grant 1411773.

  8. How do Super Star Clusters Form?: The Anomalous Luminosity Function of Natal Clusters in Henize 2-10

    NASA Astrophysics Data System (ADS)

    Biswas, I.; Johnson, K. E.

    2005-12-01

    Super Star Clusters (SSCs) are the most extreme star forming environments in the local universe. Results from optical observations have suggested that SSCs are simply the statistical tail of a power law luminosity (mass) distribution of index ˜ -2. However, optical luminosity functions are complicated by evolution effects and extinction. Free of these constraints, centimeter wave radio observations pin down the cluster luminosity function to the first few Myrs when natal SSCs are still embedded in ultradense H II regions. We investigate the earliest stages of SSCs in the starburst galaxy Henize 2-10 using high resolution Very Large Array observations at 5, 8.3, 15, and 23 GHz. We use the Pie Town link at lower frequencies to obtain relatively well matched beams to obtain a linear resolution of ˜ 10 pc. Such a high resolution should allow us to detect natal clusters with masses ˜ 104 M⊙ as 10σ detections. The 23 GHz flux (high frequency emission is dominated by optically thin, thermal emission) indicates that all of the detected SSCs in Henize 2-10 have a mass greater than ˜ 105 M⊙. We rule out the possibility of the clusters being self gravitating from the H92α line width of ˜ 200 km s-1. The absence of the formation of lower mass clusters is inconsistent with a power law luminosity function, which we verify with a KS test. Thus, the luminosity function of natal clusters, which we dub the Initial Cluster Luminosity Function (ICLF), suggests that SSCs require a special mode of star formation. We plan follow-up radio observations to investigate the behavior of the ICLF in a variety of starburst and merger environments.

  9. The bright end of the z ~ 7 UV luminosity function from a wide and deep HAWK-I survey

    NASA Astrophysics Data System (ADS)

    Castellano, M.; Fontana, A.; Paris, D.; Grazian, A.; Pentericci, L.; Boutsia, K.; Santini, P.; Testa, V.; Dickinson, M.; Giavalisco, M.; Bouwens, R.; Cuby, J.-G.; Mannucci, F.; Clément, B.; Cristiani, S.; Fiore, F.; Gallozzi, S.; Giallongo, E.; Maiolino, R.; Menci, N.; Moorwood, A.; Nonino, M.; Renzini, A.; Rosati, P.; Salimbeni, S.; Vanzella, E.

    2010-12-01

    Aims: We perform a deep search for galaxies in the redshift range 6.5 ≤ z ≤ 7.5 to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their luminosity function. Methods: We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained ~ 30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, as well as FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies with Z-Y>1, no optical detection, and flat Y-J and Y-K colour terms. Results: We detect eight high-quality candidates in the magnitude range Y = 25.5-26.5 that we add to the z-drop candidates selected in two Hawk-I pointings over the GOODS-South field. We use this full sample of 15 objects found in ~161 arcmin2 of our survey to constrain the average physical properties and the evolution of the number density of z ~ 7 LBGs. A stacking analysis yields a best-fit SED with photometric redshift z = 6.85-0.15+0.20 and an E(B-V) = 0.05-0.05+0.15. We compute a binned estimate of the z ~ 7 LF and explore the effects of photometric scatter and model uncertainties on the statistical constraints. After accounting for the expected incompleteness through MonteCarlo simulations, we strengthen our previous finding that a Schechter luminosity function constant from z = 6 to z = 7 is ruled out at a ⪆99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M1500 = -19.0, we derive a luminosity density ρUV = 1.5-0.8+2.1 × 1025 erg s-1 Hz-1 Mpc-3, implying a decrease by a factor 3.5 from z = 6 to z ≃ 6.8. We find that under standard assumptions, the emission rate of ionizing photons coming from UV bright galaxies is lower by at least a factor of two than the value

  10. A CONDITIONAL LUMINOSITY FUNCTION MODEL OF THE COSMIC FAR-INFRARED BACKGROUND ANISOTROPY POWER SPECTRUM

    SciTech Connect

    De Bernardis, Francesco; Cooray, Asantha

    2012-11-20

    The cosmic far-infrared background (CFIRB) is expected to be generated by faint, dusty star-forming galaxies during the peak epoch of galaxy formation. The anisotropy power spectrum of the CFIRB captures the spatial distribution of these galaxies in dark matter halos and the spatial distribution of dark matter halos in the large-scale structure. Existing halo models of CFIRB anisotropy power spectrum either are incomplete or lead to halo model parameters that are inconsistent with the galaxy distribution selected at other wavelengths. Here, we present a conditional luminosity function approach to describe the far-IR bright galaxies. We model the 250 {mu}m luminosity function and its evolution with redshift and model-fit the CFIRB power spectrum at 250 {mu}m measured by the Herschel Space Observatory. We introduce a redshift-dependent duty cycle parameter so that we are able to estimate the typical duration of the dusty star formation process in the dark matter halos as a function of redshifts. We find that the duty cycle of galaxies contributing to the far-IR background is 0.3-0.5 with a dusty star formation phase lasting for {approx}0.3-1.6 Gyr. This result confirms the general expectation that the far-IR background is dominated by star-forming galaxies in an extended phase, not bright starbursts that are driven by galaxy mergers and last {approx}10-100 Myr. The halo occupation number for satellite galaxies has a power-law slope that is close to unity over 0 < z < 4. We find that the minimum halo mass for dusty, star-forming galaxies with L {sub 250} > 10{sup 10} L {sub Sun} is 2 Multiplication-Sign 10{sup 11} M {sub Sun} and 3 Multiplication-Sign 10{sup 10} M {sub Sun} at z = 1 and 2, respectively. Integrating over the galaxy population with L {sub 250} > 10{sup 9} L {sub Sun }, we find that the cosmic density of dust residing in the dusty, star-forming galaxies is responsible for the background anisotropies {Omega}{sub dust} {approx} 3 Multiplication-Sign 10{sup

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

    NASA Astrophysics Data System (ADS)

    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

  12. Elliptical Accretion and Low Luminosity from High Accretion Rate Stellar Tidal Disruption Events

    NASA Astrophysics Data System (ADS)

    Svirski, Gilad; Piran, Tsvi; Krolik, Julian

    2017-05-01

    Models for tidal disruption events (TDEs) in which a supermassive black hole disrupts a star commonly assume that the highly eccentric streams of bound stellar debris promptly form a circular accretion disc at the pericentre scale. However, the bolometric peak luminosity of most TDE candidates, ˜ 1044 erg s- 1, implies that we observe only ˜1 per cent of the energy expected from radiatively efficient accretion. Even the energy that must be lost to circularize the returning tidal flow is larger than the observed energy. Recently, Piran et al. suggested that the observed optical TDE emission is powered by shocks at the apocentre between freshly infalling material and earlier arriving matter. This model explains the small radiated energy, the low temperature and the large radius implied by the observations as well as the t-5/3 light curve. However the question of the system's low bolometric efficiency remains unanswered. We suggest that the high orbital energy and low angular momentum of the flow make it possible for magnetic stresses to reduce the matter's already small angular momentum to the point at which it can fall ballistically into the supermassive black hole before circularization. As a result, the efficiency is only ˜1-10 per cent of a standard accretion disc's efficiency. Thus, the intrinsically high eccentricity of the tidal debris naturally explains why most TDE candidates are fainter than expected.

  13. Elliptical Accretion and Low Luminosity from High Accretion Rate Stellar Tidal Disruption Events

    NASA Astrophysics Data System (ADS)

    Svirski, Gilad; Piran, Tsvi; Krolik, Julian

    2017-01-01

    Models for tidal disruption events (TDEs) in which a supermassive black hole disrupts a star commonly assume that the highly eccentric streams of bound stellar debris promptly form a circular accretion disk at the pericenter scale. However, the bolometric peak luminosity of most TDE candidates, ˜ 10^{44} {erg s^{-1}}, implies that we observe only ˜1% of the energy expected from radiatively efficient accretion. Even the energy that must be lost to circularize the returning tidal flow is larger than the observed energy. Recently, Piran et al. (2015) suggested that the observed optical TDE emission is powered by shocks at the apocenter between freshly infalling material and earlier arriving matter. This model explains the small radiated energy, the low temperature, and the large radius implied by the observations as well as the t-5/3 light curve. However the question of the system's low bolometric efficiency remains unanswered. We suggest that the high orbital energy and low angular momentum of the flow make it possible for magnetic stresses to reduce the matter's already small angular momentum to the point at which it can fall ballistically into the SMBH before circularization. As a result, the efficiency is only ˜1-10% of a standard accretion disk's efficiency. Thus, the intrinsically high eccentricity of the tidal debris naturally explains why most TDE candidates are fainter than expected.

  14. Clustering, cosmology and a new era of black hole demographics- I. The conditional luminosity function of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ballantyne, D. R.

    2017-01-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of active galactic nuclei (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 AGN inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGN 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 AGN 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 illustrated at z ≈ 0 and 0.9 using the limited data that are currently available, and a clear luminosity dependence in the AGN bias and mean halo mass is predicted at both z, supporting the idea that there are at least two different modes of AGN triggering. In addition, the CLF predicts that z ≈ 0.9 quasars may be commonly hosted by haloes with Mh ˜ 1014 M⊙. These `young cluster' environments may provide the necessary interactions between gas-rich galaxies to fuel luminous accretion. The results derived from this method will be useful to populate AGN of different luminosities in cosmological simulations.

  15. THE GALAXY LUMINOSITY FUNCTIONS DOWN TO M{sub R} = -10 IN THE COMA CLUSTER

    SciTech Connect

    Yamanoi, Hitomi; Komiyama, Yutaka; Yagi, Masafumi; Iye, Masanori; Kashikawa, Nobunari; Okamura, Sadanori; Takata, Tadafumi; Furusawa, Hisanori; Yoshida, Michitoshi

    2012-08-15

    We derived the luminosity function (LF) of dwarf galaxies in the Coma Cluster down to M{sub R} = -10 at three fields located at the center, intermediate, and outskirt of the cluster. The LF (-19 < M{sub R} < -10) shows no significant differences among the three fields. It shows a clear dip at M{sub R} {approx} -13 and is composed of two distinct components of different slopes; the bright component with -19 < M{sub R} < -13 has a flatter slope than the faint component with -13 < M{sub R} < -10 which has a steep slope. The bright component (-19 < M{sub R} < -13) consists mostly of red extended galaxies including few blue galaxies whose colors are typical of late-type galaxies. On the other hand, the faint component (-13 < M{sub 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.

  16. Globular Cluster Luminosity Functions and Specific Frequencies in Dwarf Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Miller, B. W.; Lotz, J. M.

    2005-12-01

    We present the final results on the globular cluster luminosity functions (GCLFs) and specific frequencies (SN) from 69 dwarf elliptical galaxies in the HST Dwarf Elliptical Galaxy Snapshot Survey (Lotz et al. 2004). The GCLFs for the Virgo and Fornax clusters are well fit by a t5 function with a peak at MV0=-7.25 ± 0.2 and an equivalent Gaussian sigma of 1.2 magnitudes. These values are very similar to those of globular clusters systems in giant elliptical galaxies. We also confirm our previous results (Miller et al. 1998) that SN in nucleated dwarfs is about a factor of two higher than in non-nucleated dwarfs. We also discuss the fraction of the stellar mass in dwarf elliptical galaxies that is currently found in globular clusters. Supported by the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., on behalf of the international Gemini partnership of Argentina, Australia, Brazil, Canada, Chile, the United Kingdom, and the United States of America.

  17. Galaxy And Mass Assembly (GAMA): ugrizYJHK Sérsic luminosity functions and the cosmic spectral energy distribution by Hubble type

    NASA Astrophysics Data System (ADS)

    Kelvin, Lee S.; Driver, Simon P.; 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.

    2014-04-01

    We report the morphological classification of 3727 galaxies from the Galaxy and Mass Assembly survey with Mr < -17.4 mag and in the redshift range 0.025 < z < 0.06 (2.1 × 105 Mpc3) into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr and little blue spheroid classes. Approximately 70 per cent of galaxies in our sample are disc-dominated systems, with the remaining ˜30 per cent 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 energy distributions, i.e. the instantaneous energy production budget. While the observed optical/near-IR energy budget is dominated 58:42 by galaxies with a significant spheroidal component, the actual energy production rate is reversed, i.e. the combined disc-dominated populations generate ˜1.3 times as much energy as the spheroid-dominated populations. On the grandest scale, this implies that chemical evolution in the local Universe is currently largely confined to mid-type spiral classes like our Milky Way.

  18. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Luminosity Functions and the Evolution of the Cosmic Density of Molecular Gas

    NASA Astrophysics Data System (ADS)

    Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Popping, Gergö; Riechers, Dominik; Smail, Ian R.; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto J.; Bauer, Franz E.; 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; Le Fevre, Olivier; 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

    2016-12-01

    In this paper we use ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field 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 ˜ 4.5. This study is based on galaxies that have been selected solely 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 × 109 K km s-1 pc2). We find clear evidence of an evolution in the CO luminosity function with respect to z ˜ 0, with more CO-luminous galaxies present at z ˜ 2. The observed galaxies at z ˜ 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 drop by a factor of 3-10 from z ˜ 2 to z ˜ 0 (with significant error bars), and possibly a decline at z > 3. This trend is similar to the observed evolution of the cosmic star formation rate density. The latter therefore appears to be at least partly driven by the increased availability of molecular gas reservoirs at the peak of cosmic star formation (z ˜ 2).

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

    NASA Astrophysics Data System (ADS)

    Lee, Youngdae; Rey, Soo-Chang; Hilker, Michael; Sheen, Yun-Kyeong; Yi, Sukyoung K.

    2016-05-01

    We present the galaxy luminosity function (LF) of the Abell 119 cluster down to {M}r˜ -14 mag based on deep images in the u, g, and r bands taken by using MOSAIC II CCD mounted on the Blanco 4 m telescope at the CTIO. The cluster membership was accurately determined based on the radial velocity information and 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˜ 18.5 mag ({M}r˜ -17.8 mag), which is more appropriately described by a two-component function. The shape of the LF strongly depends on the clustercentric 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 associated with the surrounding, possible filamentary structure. The combined LF of the overdense regions exhibits a two-component function with a distinct dip, while the LF of the central region is well described by a single Schechter function. We suggest that, in the context of the hierarchical cluster formation scenario, the observed overdense regions are the relics of galaxy groups, retaining their two-component LFs with a dip, which acquired their shapes through a galaxy merging process in group environments, before they fall into a cluster.

  20. REVEALING PROBABLE UNIVERSAL FEATURES IN THE LOWER RED GIANT BRANCH LUMINOSITY FUNCTIONS OF GALACTIC GLOBULAR CLUSTERS

    SciTech Connect

    Kravtsov, V. V.

    2009-06-15

    This paper aims at demonstrating, for the first time, very probable universal peculiarities of the evolution of stars in the lower red giant branch (RGB) of Galactic globular clusters (GCs), reflected in two corresponding dips in the luminosity functions (LFs). By relying on the database of Hubble Space Telescope photometry of GCs, we analyze the lower RGB LFs of a sample of 18 GCs in a wide metallicity range, {delta}[Fe/H] {approx} 1.9 dex. We first show that in the F555W-(F439W-F555W) color-magnitude diagrams (CMDs), the lower RGB of GCs, except for the most metal-poor of them, frequently shows an apparent 'knee'. It reveals itself as a fairly abrupt change of the RGB slope. At the same luminosity level, the RGB LFs show a feature in the form of a more or less pronounced dip. We find that the magnitude difference between the RGB base and the given feature is, on average, around {delta} F555W{sup dip} {sub base}{approx} 1.4 mag. It shows a marginal variation with metallicity, if any, comparable to the error. At the same time, the magnitude difference between the dip and the RGB bump, {delta} F555W{sup bump} {sub dip}, decreases with increasing metallicity and falls within the range 0.8 {approx}< {delta} F555W{sup bump} {sub dip} {approx}< 1.7 mag. Generalized LFs (GLFs) have been obtained for three subsamples of GCs within limited metallicity ranges and with different horizontal branch (HB) morphology. They reproduce the 'knee-related' dip that is statistically significant in two of the GLFs. This feature turns out to be more pronounced in the GLFs of GCs with either the blue or red HB morphology than with the intermediate one. The same GLFs also reveal an additional probable universal dip. It shows up below the RGB bump at {delta} F555W slightly increasing from {approx}0.3 to {approx}0.5 mag with increasing metallicity. Also, the statistical significance of this 'prebump' dip increases, on average, toward higher metallicity. Except for the well known RGB bump, no

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

    SciTech Connect

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

    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.

  2. A Revised Planetary Nebula Luminosity Function Distance to NGC 628 Using MUSE

    NASA Astrophysics Data System (ADS)

    Kreckel, K.; Groves, B.; Bigiel, F.; Blanc, G. A.; Kruijssen, J. M. D.; Hughes, A.; Schruba, A.; Schinnerer, E.

    2017-01-01

    Distance uncertainties plague our understanding of the physical scales relevant to the physics of star formation in extragalactic studies. The planetary nebulae luminosity function (PNLF) is one of very few techniques that can provide distance estimates to within ˜10% however, it requires a planetary nebula (PN) sample that is uncontaminated by other ionizing sources. We employ optical integral field unit spectroscopy using the Multi-Unit Spectroscopic Explorer on the Very Large Telescope to measure [O iii] line fluxes for sources unresolved on 50 pc scales within the central star-forming galaxy disk of NGC 628. We use diagnostic line ratios to identify 62 PNe, 30 supernova remnants, and 87 H ii regions within our fields. Using the 36 brightest PNe, we determine a new PNLF distance modulus of {29.91}-0.13+0.08 mag (9.59{}-0.57+0.35 Mpc), which is in good agreement with literature values, but significantly larger than the previously reported PNLF distance. We are able to explain the discrepancy and recover the previous result when we reintroduce SNR contaminants to our sample. This demonstrates the power of full spectral information over narrowband imaging in isolating PNe. Given our limited spatial coverage within the Galaxy, we show that this technique can be used to refine distance estimates, even when IFU observations cover only a fraction of a galaxy disk.

  3. Semi-transparent Perovskite Solar Cells Developed by Considering Human Luminosity Function.

    PubMed

    Kim, Gyu Min; Tatsuma, Tetsu

    2017-09-06

    Semi-transparent solar cells draw a great deal of attention because their applications include, for instance, photovoltaic windows. General approach to semi-transparent cells is using thin active layers or island-type structures. Here we take human luminosity function into account, and develop solar cells that harvest photons in the wavelength regions in which human eyes are less sensitive to light. We used an organic-inorganic hybrid perovskite, which is sensitive to light particularly in the blue and deep-blue regions, and plasmonic silver nanocubes that enhance light harvesting in the red and deep-red ranges. In order to tune the plasmonic wavelength to that range, we took advantage of electrode-coupled plasmons (ECPs). We prepared non-plasmonic semi-transparent solar cells, and reduced the active layer thickness and introduced ECPs, so that the visual transparency index and power conversion efficiency of the cell were improved by 28% and 6%, respectively, of the initial values.

  4. Complete Hard X-Ray Surveys, AGN Luminosity Functions and the X-Ray Background

    NASA Technical Reports Server (NTRS)

    Tueller, Jack

    2011-01-01

    AGN are believed to make up most of the Cosmic X-Ray Background (CXB) above a few keV, but this background cannot be fully resolved at energies less than 10 keV due to absorption. The Swift/BAT and INTEGRAL missions are performing the first complete hard x-ray surveys with minimal bias due to absorption. The most recent results for both missions will be presented. Although the fraction of the CXB resolved by these surveys is small, it is possible to derive unbiased number counts and luminosity functions for AGN in the local universe. The survey energy range from 15-150 keV contains the important reflection and cutoff spectral features dominate the shape of the AGN contribution to the CXB. Average spectral characteristics of survey detected AGN will be presented and compared with model distributions. The numbers of hard x-ray blazars detected in these surveys are finally sufficient to estimate this important component's contribution the cosmic background. Constraints on CXB models and their significance will be discussed.

  5. The White Dwarf Luminosity Function and the Age of the Galaxy

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Oswalt, T. D.

    1996-12-01

    We present the results for the White Dwarf Luminosity Function (WDLF) derived from our entire sample of common proper motion binaries (CPMBs) containing white dwarfs (WDs). Approximately 170 WDs are contained in our study which makes it one of the largest samples ever used in the determination of the WDLF. We will discuss our sample selection and completion techniques and the constraint this sample places on the debate about the age of the Galaxy and ultimately the Universe. The WDs in this study were identified spectroscopically [Oswalt et al. in White Dwarfs, ed. G. Wegner, (Springer: Berlin), (1990)] and satisfy the limits [V < 18.50, mu > 0.10 "/yr] over which the sample's incompleteness is well-behaved (and hence correctible). The size of this sample allows us to set firm limits on the age of Galactic disk, making use of the latest interior [Wood, in White Dwarfs, eds. D. Koester & K. Werner (Kluwer: Dordrecht), 1995] and atmosphere [Bergeron, P., et al. Astrophys. J. 449, 258-279, 1995] models. Our new results, which strengthen the >= 9.5(+1.1}_{-0.8) Gyr(1 sigma ) age for the Galactic disk [Oswalt et al. Nature 382, 692 (1996)], will be presented. JAS gratefully acknowledges support from the NASA Graduate Student Researchers Program, grant NGT-51086 and TDO gratefully acknowledges support from NSF grant AST 90-16284.

  6. Correcting the z ˜ 8 Galaxy Luminosity Function for Gravitational Lensing Magnification Bias

    NASA Astrophysics Data System (ADS)

    Mason, Charlotte A.; Treu, Tommaso; Schmidt, Kasper B.; Collett, Thomas E.; Trenti, Michele; Marshall, Philip J.; Barone-Nugent, Robert; Bradley, Larry D.; Stiavelli, Massimo; Wyithe, Stuart

    2015-05-01

    We present a Bayesian framework to account for the magnification bias from both strong and weak gravitational lensing in estimates of high-redshift galaxy luminosity functions (LFs). We illustrate our method by estimating the z ˜ 8 UV LF using a sample of 97 Y-band dropouts (Lyman break galaxies) found in the Brightest of Reionizing Galaxies (BoRG) survey and from the literature. We find the LF is well described by a Schechter function with characteristic magnitude of {{M}\\star }=-19.85-0.35+0.30, faint-end slope of α =-1.72-0.29+0.30, and number density of {{log }10}{{{\\Psi }}\\star }(Mp{{c}-3})=-3.00-0.31+0.23. These parameters are consistent within the uncertainties with those inferred from the same sample without accounting for the magnification bias, demonstrating that the effect is small for current surveys at z ˜ 8, and cannot account for the apparent overdensity of bright galaxies compared to a Schechter function found recently by Bowler et al. and Finkelstein et al. We estimate that the probability of finding a strongly lensed z ˜ 8 source in our sample is in the range ˜3-15% depending on limiting magnitude. We identify one strongly lensed candidate and three cases of intermediate lensing in BoRG (estimated magnification μ > 1.4) in addition to the previously known candidate group-scale strong lens. Using a range of theoretical LFs we conclude that magnification bias will dominate wide field surveys—such as those planned for the Euclid and WFIRST missions—especially at z > 10. Magnification bias will need to be accounted for in order to derive accurate estimates of high-redshift LFs in these surveys and to distinguish between galaxy formation models.

  7. The effect on Earth's surface temperature from variations in rotation rate, continent formation, solar luminosity, and carbon dioxide.

    PubMed

    Kuhn, W R; Walker, J C; Marshall, H G

    1989-08-20

    Proposed evolutionary histories of solar luminosity, atmospheric carbon dioxide amounts, Earth rotation rate, and continent formation have been used to generate a time evolution of Earth's surface temperature. While speculative because of uncertainties in the input parameters, such a study does help to prioritize the areas of most concern to paleoclimatic research while illustrating the relationships and mutual dependencies. The mean temperature averages about 5 K higher than today over most of geologic time; the overall variation is less than 15 K. The evolution of Earth's rotation rate makes a significant contribution to the surface temperature distribution as late as 0.5 b.y. ago. While there is little change in equatorial temperatures, polar temperatures decrease, being some 15 K lower 3.5 b.y. ago than with present day rotation. The effect of continent growth on albedo is of secondary importance.

  8. THE CANADA-FRANCE HIGH-z QUASAR SURVEY: NINE NEW QUASARS AND THE LUMINOSITY FUNCTION AT REDSHIFT 6

    SciTech Connect

    Willott, Chris J.; Crampton, David; Hutchings, John B.; Schade, David; Delorme, Philippe; Reyle, Celine; Albert, Loic; Bergeron, Jacqueline; Omont, Alain; Delfosse, Xavier; Forveille, Thierry; McLure, Ross J.

    2010-03-15

    We present discovery imaging and spectroscopy for nine new z {approx} 6 quasars found in the Canada-France High-z Quasar Survey (CFHQS) bringing the total number of CFHQS quasars to 19. By combining the CFHQS with the more luminous Sloan Digital Sky Survey sample, we are able to derive the quasar luminosity function from a sample of 40 quasars at redshifts 5.74 < z < 6.42. Our binned luminosity function shows a slightly lower normalization and flatter slope than found in previous work. The binned data also suggest a break in the luminosity function at M {sub 1450} {approx} -25. A double power-law maximum likelihood fit to the data is consistent with the binned results. The luminosity function is strongly constrained (1{sigma} uncertainty <0.1 dex) over the range -27.5 < M {sub 1450} < -24.7. The best-fit parameters are {phi}(M*{sub 1450}) = 1.14 x 10{sup -8} Mpc{sup -3} mag{sup -1}, break magnitude M*{sub 1450} = -25.13, and bright end slope {beta} = -2.81. However, the covariance between {beta} and M*{sub 1450} prevents strong constraints being placed on either parameter. For a break magnitude in the range -26 < M*{sub 1450} < -24, we find -3.8 < {beta} < -2.3 at 95% confidence. We calculate the z = 6 quasar intergalactic ionizing flux and show it is between 20 and 100 times lower than that necessary for reionization. Finally, we use the luminosity function to predict how many higher redshift quasars may be discovered in future near-IR imaging surveys.

  9. The VIMOS-VLT deep survey. Evolution of the galaxy luminosity function up to z = 2 in first epoch data

    NASA Astrophysics Data System (ADS)

    Ilbert, O.; Tresse, L.; Zucca, E.; Bardelli, S.; Arnouts, S.; Zamorani, G.; Pozzetti, L.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Picat, J.-P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Bolzonella, M.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; Meneux, B.; Merighi, R.; Paltani, S.; Pello, R.; Pollo, A.; Radovich, M.; Bondi, M.; Bongiorno, A.; Busarello, G.; Ciliegi, P.; Lamareille, F.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.

    2005-09-01

    We investigate the evolution of the galaxy luminosity function from the VIMOS-VLT Deep Survey (VVDS) from the present to z = 2 in five (U, B, V, R and I) rest-frame band-passes. We use the first epoch VVDS deep sample of 11 034 spectra selected at 17.5 ≤ IAB ≤ 24.0, on which we apply the Algorithm for Luminosity Function (ALF), described in this paper. We observe a substantial evolution with redshift of the global luminosity functions in all bands. From z = 0.05 to z = 2, we measure a brightening of the characteristic magnitude M* included in the magnitude range 1.8-2.5, 1.7-2.4, 1.2-1.9, 1.1-1.8 and 1.0-1.6 in the U, B, V, R and I rest-frame bands, respectively. We confirm this differential evolution of the luminosity function with rest-frame wavelength from the measurement of the comoving density of bright galaxies (M ≤ M*(z = 0.1)). This density increases by a factor of around 2.6, 2.2, 1.8, 1.5, 1.5 between z=0.05 and z=1 in the U, B, V, R, I bands, respectively. We also measure a possible steepening of the faint-end slope of the luminosity functions, with Δα ˜ -0.3 between z=0.05 and z=1, similar in all bands.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    High-precision HST photometry has 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 estimate that the fraction of binary systems in NGC 2808 is fbin ≃ 0.05, and find that the three MSs have very similar LFs. The slopes of the corresponding MFs are α = -1.2 ± 0.3 for the red MS, α = -0.9 ± 0.3 for the middle MS, and α = -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 ≤ 0.6ℳ⊙ 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, and provide constraints on models of the formation and evolution of multiple generations of stars in these objects. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under the programs GO-9899 and GO-10922.Appendices are available in electronic form at http://www.aanda.org

  11. The H-alpha luminosity function at redshift 2.2 . A new determination using VLT/HAWK-I

    NASA Astrophysics Data System (ADS)

    Hayes, M.; Schaerer, D.; Östlin, G.

    2010-01-01

    We aim to place new, strengthened constraints on the luminosity function (LF) of H-alpha (Hα) emitting galaxies at redshift z≈ 2.2, and to further constrain the instantaneous star-formation rate density of the universe (dotρstar). We have used the new HAWK-I instrument at ESO-VLT to obtain extremely deep narrow-band (line; NB2090) and broad-band (continuum; {K_s}) imaging observations. The target field is in the GOODS-South, providing us with a rich multi-wavelength auxiliary data set, which we utilise for redshift confirmation and to estimate dust content. We use this new data to measure the faint-end slope (α) of LF(Hα) with unprecedented precision. The data are well fit by a Schechter function and also a single power-law, yielding α = (-1.72± 0.20) and (-1.77± 0.21), respectively. Thus we are able to confirm the steepening of α from low- to high-z predicted by a number of authors and observed at other wavelengths. We combine our LF data-points with those from a much shallower but wider survey at z˜ 2.2 (Geach et al. 2008), constructing a LF spanning a factor of 50 in luminosity. Re-fitting the Schechter parameters, we obtain log L_star = (43.07± 0.22) erg s-1; log φ_star = (-3.45± 0.52) Mpc-3; α = (-1.60± 0.15). We integrate over LF(Hα) and apply a correction for dust attenuation to determine the instantaneous cosmic star-formation rate density at z˜ 2 without assuming α or extrapolating it from lower-z. Our measurement of dotρstar is (0.215± 0.090) M⊙ yr-1 Mpc-3, integrated over a range of 37≤ log (LHα /erg s-1)≤ 47. Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 081.A-0932.

  12. Inclination-dependent Luminosity Function of Spiral Galaxies in the Sloan Digital Sky Survey: Implications for Dust Extinction

    NASA Astrophysics Data System (ADS)

    Shao, Zhengyi; Xiao, Quanbao; Shen, Shiyin; Mo, H. J.; Xia, Xiaoyang; Deng, Zugan

    2007-04-01

    Using a sample of 61,506 spiral galaxies selected from the SDSS DR2, we examine the luminosity function (LF) of spiral galaxies with different inclination angles. We find that the characteristic luminosity of the LF, L*, decreases with increasing inclination, while the faint-end slope, α, depends only weakly on it. The inclination dependence of the LF is consistent with that expected from a simple model in which the optical depth is proportional to the cosine of the inclination angle, and we use a likelihood method to recover both the coefficient in front of the cosine, γ, and the LF for galaxies viewed face-on. The value of γ is quite independent of galaxy luminosity in a given band, and the values of γ obtained in this way for the five SDSS bands give an extinction curve that is a power law of wavelength (τ~λ-n), with a power index of n=0.96+/-0.04. Using the dust extinction for galaxies obtained by Kauffmann and coworkers, we derive an ``extinction-corrected'' luminosity function for spiral galaxies. Dust extinction makes M* dimmer by ~0.5 mag in the z band and by ~1.2 mag in the u band. Since our analysis is based on a sample in which selection effects are well under control, the dimming of edge-on galaxies relative to face-on galaxies is best explained by assuming that galaxy disks are optically thick in dust absorption.

  13. High–frequency cluster radio galaxies: Luminosity functions and implications for SZE–selected cluster samples

    DOE PAGES

    Gupta, Nikhel; Saro, A.; Mohr, J. J.; ...

    2017-01-15

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the meta-catalogue of X-ray-detected clusters of galaxies (MCXC; < z > = 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 deg2 SPT-SZ survey maps at the locations of SUMSS sources, producing a multifrequency catalogue 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 ismore » negative at these frequencies. We employ a cluster SZE model to remove the expected flux bias and then study these corrected source catalogues. 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. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass–observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 per cent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. As a result, allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 per cent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.« less

  14. The global 21-cm signal in the context of the high- z galaxy luminosity function

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan; Furlanetto, Steven R.; Sun, Guochao

    2017-01-01

    We build a new model for the global 21-cm signal that is calibrated to measurements of the high-z galaxy luminosity function (LF) and further tuned to match the Thomson scattering optical depth of the cosmic microwave background, τe. Assuming that the z ≲ 8 galaxy population can be smoothly extrapolated to higher redshifts, the recent decline in best-fitting values of τe and the inefficient heating induced by X-ray binaries (the presumptive sources of the high-z X-ray background) imply that the entirety of cosmic reionization and reheating occurs at z ≲ 12. In contrast to past global 21-cm models, whose z ˜ 20 (ν ˜ 70 MHz) absorption features and strong ˜25 mK emission features were driven largely by the assumption of efficient early star formation and X-ray heating, our new models peak in absorption at ν ˜ 110 MHz at depths ˜-160 mK and have negligible emission components. Current uncertainties in the faint-end of the LF, binary populations in star-forming galaxies, and UV and X-ray escape fractions introduce ˜20 MHz (˜50 mK) deviations in the trough's frequency (amplitude), while emission signals remain weak (≲10 mK) and are confined to ν ≳ 140 MHz. These predictions, which are intentionally conservative, suggest that the detection of a 21-cm absorption minimum at frequencies below ˜90 MHz and/or emission signals stronger than ˜10mK at ν ≲ 140 MHz would provide strong evidence for `new' sources at high redshifts, such as Population III stars and their remnants.

  15. Deep UV Luminosity Functions at the Infall Region of the Coma Cluster

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Yue, Bin; Ferrara, Andrea; Xu, Yidong

    2016-12-01

    Recent measurements of the luminosity function (LF) of galaxies in the Epoch of Reionization (EoR, z ≳ 6) indicate a very steep increase of the number density of low-mass galaxies populating the LF faint-end. However, as star formation in low-mass haloes can be easily depressed or even quenched by ionizing radiation, a turnover is expected at some faint UV magnitudes. Using a physically motivated analytical model, we quantify reionization feedback effects on the LF faint-end shape. We find that if reionization feedback is neglected, the power-law Schechter parametrization characterizing the LF faint-end remains valid up to absolute UV magnitude ˜-9. If instead radiative feedback is strong enough that quenches star formation in haloes with circular velocity smaller than 50 km s-1, the LF starts to drop at absolute UV magnitude ˜-15, i.e. slightly below the detection limits of current (unlensed) surveys at z ˜ 5. The LFs may rise again at higher absolute UV magnitude, where, as a result of interplay between reionization process and galaxy formation, most of the galaxy light is from relic stars formed before the EoR. We suggest that the galaxy number counts data, particularly in lensed fields, can put strong constraints on reionization feedback. In models with stronger reionization feedback, stars in galaxies with absolute UV magnitude higher than ˜-13 and smaller than ˜-8 are typically older. Hence, the stellar age-UV magnitude relation can be used as an alternative feedback probe.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    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; = 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 deg2 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. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass-observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 percent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. Allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 percent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.

  18. DEEP ULTRAVIOLET LUMINOSITY FUNCTIONS AT THE INFALL REGION OF THE COMA CLUSTER

    SciTech Connect

    Hammer, D. M.; Hornschemeier, A. E.; Jenkins, L.; Salim, S.; Smith, R.; Mobasher, B.; Miller, N.; Ferguson, H.

    2012-02-01

    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 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} Almost-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 parameterization of the UV LFs resulting in a faint-end slope of {alpha} Almost-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} Almost-Equal-To -14 owing to a deficit of dwarf star-forming galaxies in Coma with stellar masses below M{sub *} = 10{sup 8} M{sub Sun }. 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.

  19. High-frequency cluster radio galaxies: luminosity functions and implications for SZE-selected cluster samples

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the meta-catalogue of X-ray-detected clusters of galaxies (MCXC; = 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 deg2 SPT-SZ survey maps at the locations of SUMSS sources, producing a multifrequency catalogue 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 catalogues. 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. We use the 150 GHz LF to estimate the impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy flux typically produces a small bias on the SZE signal and has negligible impact on the observed scatter in the SZE mass-observable relation. If we assume there is no redshift evolution in the radio galaxy LF then 1.8 ± 0.7 per cent of the clusters with detection significance ξ ≥ 4.5 would be lost from the sample. Allowing for redshift evolution of the form (1 + z)2.5 increases the incompleteness to 5.6 ± 1.0 per cent. Improved constraints on the evolution of the cluster radio galaxy LF require a larger cluster sample extending to higher redshift.

  20. The hard X-ray luminosity function of high-redshift (3 < z ≲ 5) active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Vito, F.; Gilli, R.; Vignali, C.; Comastri, A.; Brusa, M.; Cappelluti, N.; Iwasawa, K.

    2014-12-01

    We present the hard-band (2-10 keV) X-ray luminosity function (HXLF) of 0.5-2 keV band selected active galactic nuclei (AGN) at high redshift. We have assembled a sample of 141 AGN at 3 < z ≲ 5 from X-ray surveys of different size and depth, in order to sample different regions in the LX - z plane. The HXLF is fitted in the range log LX ˜ 43-45 with standard analytical evolutionary models through a maximum likelihood procedure. The evolution of the HXLF is well described by a pure density evolution, with the AGN space density declining by a factor of ˜10 from z = 3 to 5. A luminosity-dependent density evolution model, which, normally, best represents the HXLF evolution at lower redshift, is also consistent with the data, but a larger sample of low-luminosity (log LX < 44), high-redshift AGN is necessary to constrain this model. We also estimated the intrinsic fraction of AGN obscured by a column density log NH ≥ 23 to be 0.54 ± 0.05, with no strong dependence on luminosity. This fraction is higher than the value in the Local Universe, suggesting an evolution of the luminous (LX > 1044 erg s-1) obscured AGN fraction from z = 0 to z > 3.

  1. THE FAINT-END SLOPE OF THE REDSHIFT 5.7 Ly{alpha} LUMINOSITY FUNCTION

    SciTech Connect

    Henry, Alaina L.; Martin, Crystal L.; Dressler, Alan; McCarthy, Patrick; Sawicki, Marcin

    2012-01-10

    Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultra-faint emission-line galaxies recently reported by Dressler et al. We confirm six Ly{alpha} emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s{sup -1} redward of the peak emission. With these six LAEs, we revise our previous estimate of the number of faint LAEs in the Dressler et al. survey. Combining these data with the density of bright LAEs in the Cosmic Evolution Survey and Subaru Deep Field provides the best constraints to date on the redshift 5.7 LAE luminosity function (LF). Schechter function parameters, {phi}* = 4.5 Multiplication-Sign 10{sup -4} Mpc{sup -3}, L* = 9.1 Multiplication-Sign 10{sup 42} erg s{sup -1}, and {alpha} = -1.70, are estimated using a maximum likelihood technique with a model for slit-losses. To place this result in the context of the UV-selected galaxy population, we investigate how various parameterizations of the Ly{alpha} equivalent width distribution, along with the measured UV-continuum LF, affect shape and normalization of the Ly{alpha} LF. The nominal model, which uses z {approx} 6 equivalent widths from the literature, falls short of the observed space density of LAEs at the bright end, possibly indicating a need for higher equivalent widths. This parameterization of the equivalent width distribution implies that as many as 50% of our faintest LAEs should have M{sub UV} > -18.0, rendering them undetectable in even the deepest Hubble Space Telescope surveys at this redshift. Hence, ultra-deep emission-line surveys find some of the faintest galaxies ever observed at the end of the reionization epoch. Such faint galaxies likely enrich the intergalactic medium with metals and maintain its ionized state in the post-reionization era. Observations of these objects provide a glimpse of the building blocks of present-day galaxies at an early time.

  2. The Luminosity Function of Quasars (active Galactic Nuclei) in a Merging Model with the Eddington Limit Taken Into Account

    NASA Astrophysics Data System (ADS)

    Kontorovich, V. M.; Krivitsky, D. S.

    The influence of Eddington's limit on the active galactic nuclei (AGN) luminosity function within the framework of a phenomenological activity model (Kats and Kontorovich, 1990, 1991) based on angular momentum compensation in the process of galaxy merging is investigated. In particular, it is shown that in spite of the essential dependence of the galaxy merging probability on their masses in the most important and interesting case it behaves effectively as a constant, so that the abovementioned (Kats and Kontorovich, 1991) correspondence between the observed galaxy mass function (Binggeli et al., 1988) and quasar luminosity function power exponents (Boyle et al., 1988; Koo and Kron, 1988; Cristiani et al., 1993) for a constant merger probability takes place in reality. A break in the power-law dependence of the luminosity function due to Eddington's restriction (cf. Dibai, 1981; Padovani and Rafanelli, 1988) is obtained in certain cases. Possible correlation between masses of black holes in AGN and masses of their host galaxies is discussed. A more detailed paper containing the results presented at this conference was published in Pis'ma v Astron. Zh. (Kontorovich and Krivitsky, 1995). Here we have added also some additional notes and references.

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

    NASA Astrophysics Data System (ADS)

    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

  4. Spectral analysis of the Stromlo-APM Survey - II. Galaxy luminosity function and clustering by spectral type

    NASA Astrophysics Data System (ADS)

    Loveday, J.; Tresse, L.; Maddox, S.

    1999-11-01

    We study the luminosity function and clustering properties of subsamples of local galaxies selected from the Stromlo-APM Survey by the rest-frame equivalent widths of their Hα and [Oii] emission lines. The bJ luminosity function of star-forming galaxies has a significantly steeper faint-end slope than that for quiescent galaxies: the majority of sub-L* galaxies are currently undergoing significant star formation. Emission-line galaxies are less strongly clustered, both amongst themselves and with the general galaxy population, than are quiescent galaxies. Thus as well as being less luminous, star-forming galaxies also inhabit lower density regions of the Universe than quiescent galaxies.

  5. The gamma-ray luminosity function of millisecond pulsars and implications for the GeV excess

    SciTech Connect

    Hooper, Dan; Mohlabeng, Gopolang E-mail: gopolang.mohlabeng@ku.edu

    2016-03-01

    It has been proposed that a large population of unresolved millisecond pulsars (MSPs) could potentially account for the excess of GeV-scale gamma-rays observed from the region surrounding the Galactic Center. The viability of this scenario depends critically on the gamma-ray luminosity function of this source population, which determines how many MSPs Fermi should have already detected as resolved point sources. In this paper, we revisit the gamma-ray luminosity function of MSPs, without relying on uncertain distance measurements. Our determination, based on a comparison of models with the observed characteristics of the MSP population, suggests that Fermi should have already detected a significant number of sources associated with such a hypothesized Inner Galaxy population. We cannot rule out a scenario in which the MSPs residing near the Galactic Center are systematically less luminous than those present in the Galactic Plane or within globular clusters.

  6. The gamma-ray luminosity function of millisecond pulsars and implications for the GeV excess

    SciTech Connect

    Hooper, Dan; Mohlabeng, Gopolang

    2016-03-29

    It has been proposed that a large population of unresolved millisecond pulsars (MSPs) could potentially account for the excess of GeV-scale gamma-rays observed from the region surrounding the Galactic Center. The viability of this scenario depends critically on the gamma-ray luminosity function of this source population, which determines how many MSPs Fermi should have already detected as resolved point sources. In this paper, we revisit the gamma-ray luminosity function of MSPs, without relying on uncertain distance measurements. Our determination, based on a comparison of models with the observed characteristics of the MSP population, suggests that Fermi should have already detected a significant number of sources associated with such a hypothesized Inner Galaxy population. As a result, we cannot rule out a scenario in which the MSPs residing near the Galactic Center are systematically less luminous than those present in the Galactic Plane or within globular clusters.

  7. The gamma-ray luminosity function of millisecond pulsars and implications for the GeV excess

    DOE PAGES

    Hooper, Dan; Mohlabeng, Gopolang

    2016-03-29

    It has been proposed that a large population of unresolved millisecond pulsars (MSPs) could potentially account for the excess of GeV-scale gamma-rays observed from the region surrounding the Galactic Center. The viability of this scenario depends critically on the gamma-ray luminosity function of this source population, which determines how many MSPs Fermi should have already detected as resolved point sources. In this paper, we revisit the gamma-ray luminosity function of MSPs, without relying on uncertain distance measurements. Our determination, based on a comparison of models with the observed characteristics of the MSP population, suggests that Fermi should have already detectedmore » a significant number of sources associated with such a hypothesized Inner Galaxy population. As a result, we cannot rule out a scenario in which the MSPs residing near the Galactic Center are systematically less luminous than those present in the Galactic Plane or within globular clusters.« less

  8. Confirmation of a Steep Luminosity Function for Ly alpha Emitters at z 5.7: a Major Component of Reionization

    NASA Technical Reports Server (NTRS)

    Dressler, Alan; Henry, Alaina L.; Martin, Crystal L.; Sawicki, Marcin; McCarthy, Patrick; Villaneuva, Edward

    2014-01-01

    We report the first direct and robust measurement of the faint-end slope of the Ly-alpha emitter (LAE) luminosity function at z = 5.7. Candidate LAEs from a low-spectral-resolution blind search with IMACS on Magellan- Baade were targeted at higher resolution to distinguish high redshift LAEs from foreground galaxies. All but 2 of our 42 single-emission-line systems are fainter than F = 2.0×10(exp-17) ergs s(exp-1) cm(exp-2), making these the faintest emission-lines observed for a z = 5.7 sample with known completeness, an essential property for determining the faint end slope of the LAE luminosity function. We find 13 LAEs as compared to 29 foreground galaxies, in very good agreement with the modeled foreground counts predicted in Dressler et al. (2011a) that had been used to estimate a faint-end slope of alpha = -2.0 for the LAE luminosity function. A 32% LAE fraction, LAE/(LAE+foreground) within the flux interval F = 2-20 × 10(exp-18) ergs s(exp-1) cm(exp-2) constrains the faint end slope of the luminosity function to -1.95 greater than alpha greater than -2.35 (1 delta). We show how this steep LF should provide, to the limit of our observations, more than 20% of the flux necessary to maintain ionization at z = 5.7, with a factor-of-ten extrapolation in flux reaching more than 55%. We suggest that this bodes well for a comparable contribution by similar, low-mass star forming galaxies at higher-redshift - within the reionization epoch at z greater than approximately 7, only 250 Myr earlier - and that such systems provide a substantial, if not dominant, contribution to the late-stage reionization of the IGM.

  9. H II Regions in Spiral Galaxies: Size Distribution, Luminosity Function, and New Isochrone Diagnostics of Density-Wave Kinematics

    DTIC Science & Technology

    2003-11-01

    conjecture to physical galaxies , placing the corotation where the distribution of H ii regions is seen to end. Tremaine & Weinberg (1984) developed an...H ii REGIONS IN SPIRAL GALAXIES : SIZE DISTRIBUTION, LUMINOSITY FUNCTION, AND NEW ISOCHRONE DIAGNOSTICS OF DENSITY-WAVE KINEMATICS M. S. Oey Lowell...Department of Physics and Astronomy, JohnsHopkins University, 3400 North Charles Street, Baltimore, MD 21218 and Xiaolei Zhang Remote Sensing Division

  10. The K-Band Quasar Luminosity Function from an SDSS and UKIDSS Matched Catalog

    NASA Astrophysics Data System (ADS)

    Peth, Michael; Ross, N. P.; Schneider, D. P.

    2010-01-01

    We match the 1,015,082 quasars from the Sloan Digital Sky Survey (SDSS) DR6 Photometric Quasar catalog to the UKIRT Infrared Digital Sky Survey (UKIDSS) Large Area Survey (LAS) DR3 to produce a catalog of 130,827 objects with optical (ugriz) and infrared (YJHK) measurements over an area of 1,200 sq. deg. A matching radius of 1'’ is used; the positional standard deviations of SDSS DR6 quasars and UKIDSS LAS is δRA = 0.137'’ and δDec = 0.131''. The catalog contains 74,351 K-band detections and 42,133 objects have coverage in all four NIR bands. In addition to the catalog, we present optical and NIR color-redshift and color-color plots. The photometric vs. spectroscopic redshift plots demonstrate how unreliable high reported photometric redshifts can be. This forces us to focus on z4.6 quasars are compared to our highest redshift objects. The giK color-color plot demonstrates that stellar contamination only affects a small sample of the objects. Distributions for Y,J,H,K and i-bands reveal insights into the flux limits in each magnitude. We investigate the distribution of redshifts from different data sets and investigate the legitimacy of certain measured photometric redshift regions. For in-depth analysis, we focus on the 300 sq. deg area equatorial SDSS region designated as Stripe 82. We measure the observed K-band quasar luminosity function (QLF) for a subset of 9,872, z<2.2 objects. We find the shape of the K-band QLF is very similar to that of the optical QLF, over the considered redshift ranges. Our calculated K-Band QLFs broadly match previous optical QLFs calculated from the SDSS and 2SLAQ QSO surveys and should provide important constraints linking unobscured optical quasars to Mid-Infrared detected, dusty and obscured AGNs at high-redshift.

  11. A critical analysis of the UV luminosity function at redshift ~7 from deep WFC3 data

    NASA Astrophysics Data System (ADS)

    Grazian, A.; Castellano, M.; Koekemoer, A. M.; Fontana, A.; Pentericci, L.; Testa, V.; Boutsia, K.; Giallongo, E.; Giavalisco, M.; Santini, P.

    2011-08-01

    Context. The study of the luminosity function (LF) of Lyman break galaxies (LBGs) at z = 7 is very important for ascertaining their role in the reionization of the Universe. These galaxies can be used also to investigate in detail the processes of formation and evolution of galactic structures in the infancy of our Universe. Aims: In this work we plan to perform a detailed and critical analysis of the statistical and systematic errors in the z ~ 7 LF determination. Methods: To this aim, we have assembled a large sample of candidate LBGs at z ~ 7 from different surveys, spanning a large variety of areas and depths. In particular, we have combined data from the deep (J < 27.4) and ultradeep (J < 29.2) surveys recently acquired with the new WFC3 NIR camera on HST, over the GOODS-ERS (~40 sq. arcmin) and the HUDF (~4 sq. arcmin) fields, with ground based surveys in wide and shallow areas from Hawk-I@VLT and HyperSuprimecam@Subaru. We have used public ACS images in the z band to select z-dropout galaxies, and other public data both in the blue (BVI) and in the red bands to reject possible low-redshift interlopers. We have compared our results with extensive Monte Carlo simulations to quantify the observational effects of our selection criteria as well as the effects of photometric scatter, color selections or the morphology of the candidates. Results: We have found that the number density of faint LBGs at z ~ 7 is only marginally sensitive to the color selection adopted, but it is strongly dependent from the assumption made on the half light distributions of the simulated galaxies, used to correct the observed sample for incompleteness. The slope of the faint end of the LBGs LF has thus a rather large uncertainty, due to the unknown distribution of physical sizes of the z ~ 7 LBGs. The implications of these uncertainties have been neglected by previous works. Conclusions: We conclude that galaxies at z ~ 7 are unable to reionize the Universe unless there is a

  12. The Faint-End Slopes of Galaxy Luminosity Functions in the COSMOS Field

    NASA Astrophysics Data System (ADS)

    Liu, Charles T.; Capak, Peter; Mobasher, Bahram; Paglione, Timothy A. D.; Rich, R. Michael; Scoville, Nicholas Z.; Tribiano, Shana M.; Tyson, Neil D.

    2008-01-01

    We examine the faint-end slope of the rest-frame V-band luminosity function (LF), with respect to galaxy spectral type, of field galaxies with redshift z < 0.5, using a sample of 80,820 galaxies with photometric redshifts in the 2 deg2 Cosmic Evolution Survey (COSMOS) field. For all galaxy spectral types combined, the LF slope ranges from -1.24 to -1.12, from the lowest redshift bin to the highest. In the lowest redshift bin (0.02 < z < 0.1), where the magnitude limit is MVlesssim - 13, the slope ranges from α ~ - 1.1 for galaxies with early-type spectral energy distributions (SEDs) to α ~ - 1.9 for galaxies with low-extinction starburst SEDs. In each galaxy SED category (early-type, Sbc, Scd+Irr, and starburst), the faint-end slopes grow shallower with increasing redshift; in the highest redshift bin (0.4 < z < 0.5), α ~ - 0.5 and -1.3 for early types and starbursts, respectively. The steepness of α at lower redshifts could be qualitatively explained by LF evolution, or by large numbers of faint dwarf galaxies, perhaps of low surface brightness, that are not detected at higher redshifts. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555; also based on data collected at Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which are operated by AURA, Inc., under cooperative agreement with the National Science Foundation; at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; at the European Southern Observatory under Large Program 175.A-0839, Chile; at the Canada-France-Hawaii Telescope with MegaPrime/MegaCam, operated as a joint project by the CFHT

  13. The Luminosity Function of Star Clusters in 20 Star-Forming Galaxies Based on Hubble Legacy Archive Photometry

    NASA Astrophysics Data System (ADS)

    Bowers, Ariel; Whitmore, B. C.; Chandar, R.; Larsen, S. S.

    2014-01-01

    Luminosity functions have been determined for star cluster populations in 20 nearby (4 - 30 Mpc), star-forming galaxies based on ACS source lists generated by the Hubble Legacy Archive (http://hla.stsci.edu). 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 luminosity function can be approximated by a power-law, dN/dL ∝ Lα, with an average value for α of -2.37 and rms scatter = 0.18. A comparison of fitting results based on methods which 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 steper luminosity functions. Our uniform database results in a small scatter (0.5 magnitude) in the correlation between the magnitude of the brightest cluster (Mbrightest) and Log of the number of clusters brighter than MI = -9 (Log N). We also examine the magnitude of the brightest cluster vs. Log SFR for a sample including LIRGS and ULIRGS.

  14. The z~4 Quasar Luminosity Function: Implications for supermassive black hole growth, reionization, and future time domain surveys

    NASA Astrophysics Data System (ADS)

    AlSayyad, Yusra; Connolly, Andrew J.; McGreer, Ian D.; Ivezic, Zeljko; Fan, Xiaohui; LSST Data Management

    2017-01-01

    Upcoming time-domain imaging surveys such as the LSST will detect over a million high-redshift (z > 4) quasars, making complete spectroscopic followup unfeasible. Statistical estimates such as luminosity functions and clustering measurements will require purely photometric methods for classifying objects, estimating redshifts and estimating selection functions. We develop these methods and constrain the optical, type I quasar luminosity function (QLF) at 3.75 < z < 4.5 for -27.5 < M1450 < -23.5. Using the Sloan Digital Sky Survey (SDSS) repeated imaging of the 275 sq. deg. equatorial region of the sky (50 < R.A. < +60; -1.26 < Dec. < +1.26) known as Stripe 82, we extracted 40 million new lightcurves using the LSST data management software and selected a statistical sample of z~4 quasars based on colors and variability metrics. We confirmed these using a spectroscopically complete 55 sq. deg. sub-region augmented with 102 new spectroscopic observations of quasars at z > 3.4 with i < 22.5. We present the first variability-selected QLF measurement at high redshift (z > 3.75) and constraint on the characteristic luminosity M*1450 = -26.7 from a single, uniformly-selected survey at z~4.

  15. The Trivariate / Radio Optical X-Ray / Luminosity Function CD Galaxies - Part Two - the Fuelling of Radio Sources

    NASA Astrophysics Data System (ADS)

    Valentijn, E. A.; Bijleveld, W.

    1983-09-01

    In order to the test the hypothesis that radio sources in elliptical galaxies are fuelled by a fraction of accreted X-ray gas, a sample of 81 cD galaxies in clusters and 23 cD galaxies in poor groups is studied. Various subsamples have been defined (reviewed in Table t) according to the origin of the cD galaxy classification (optically, radio or X-ray selected). A catalogue is presented, listing the measured optical, radio and X-ray luminosities from various origins, but all transformed to a uniform and homogeneous system: optical Mv (38 kpc metric diameter), radio P1.4 (1.4 GHz monochromatic total radio power) and Lx (1 Mpc metric diameter 0.5-3.0 keV X-ray band). The three luminosity parameters are investigated for cross- correlations by studying power-power plots and by analysing how the integral radio luminosity function, expressed in fractions of radio detections (F(> P1.4)), depend on Mv and Lx. All three parameters are found to correlate with each other. F(> P1.4) increases with both increasing Lx and brighter Mv and Lx also increases with brighter Mv. The determinations of the different regression relations are internally consistent. The empirical conclusions from the analysis are: (i) The mean Mv of poor group cDs is 0.m4 fainter than the mean Mv of cluster cDs. (ii) The bivariate radio luminosity functions of both samples confirm, both in shape and in their dependence on Mv, those of normal and giant ellipticals. (iii) cD galaxies have an increasing probability to contain a central (≲ 28 kpc) radio source when the X-ray luminosity of their halo (˜1 Mpc diameter) increases. 50 ± 9% of Lx ≧ 1044 erg s-1 cDs have a central radio source with P1.4 ≧ 1024WHz-1, while 12+l2-5% of Lx < 1043 ergs-1 cDs have a radio source of that power. This important conclusion is summarised in Fig. 5. (iv) Comparing rich cluster cDs and poor group cDs a relation between Mv and Lx is found. This relation holds among the rich cluster cDs as well. The physical origins of

  16. FAR-IR/SUBMILLIMETER SPECTROSCOPIC COSMOLOGICAL SURVEYS: PREDICTIONS OF INFRARED LINE LUMINOSITY FUNCTIONS FOR z < 4 GALAXIES

    SciTech Connect

    Spinoglio, Luigi; Dasyra, Kalliopi M.; Gruppioni, Carlotta; Valiante, Elisabetta; Isaak, Kate

    2012-02-01

    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 submillimeter 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, i.e., the Space Infrared telescope for Cosmology and Astrophysics and the Cerro Chajnantor Atacama Telescope, will be able to observe thousands of z > 1 galaxies in key fine-structure lines, e.g., [Si II], [O I], [O III], [C II], in a half-square-degree survey, with 1 hr integration time per field of view. Fainter lines such as [O IV], [Ne V], and H{sub 2} (0-0)S1 will be observed in several tens of bright galaxies at 1 < z < 2, while diagnostic diagrams of active nucleus versus star formation activity will be feasible even for normal z {approx} 1 galaxies. We discuss the new parameter space that these future telescopes will cover and that strongly motivates their construction.

  17. Evidence for evolution of the luminosity function of clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Edge, A. 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.

  18. Evidence for evolution of the luminosity function of clusters of galaxies

    NASA Technical Reports Server (NTRS)

    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.

  19. Supernova remnants in the Local Group - I. A model for the radio luminosity function and visibility times of supernova remnants

    NASA Astrophysics Data System (ADS)

    Sarbadhicary, Sumit K.; Badenes, Carles; Chomiuk, Laura; Caprioli, Damiano; Huizenga, Daniel

    2017-01-01

    Supernova remnants (SNRs) in Local Group galaxies offer unique insights into the origin of different types of supernovae (SNe). 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 interstellar medium (ISM) and stellar mass distribution in the host galaxy from multi-wavelength images and the current understanding of electron acceleration and magnetic 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 ˜3.1 × 10-3 per year and an electron acceleration efficiency, ɛe ˜ 4.2 × 10-3. We predict that the radio visibility times of ˜70 per cent of M33 SNRs will be determined by their Sedov-Taylor lifetimes, and correlated with the measured ISM column density, NH (t_{vis} ∝ N_H^{-a}, with a ˜ 0.33) while the remaining will have visibility times determined by the detection limit of the radio survey. These observational constraints on the visibility time of SNRs will allow us to use SNR catalogues as `SN surveys' to calculate SN rates and delay-time distributions in the Local Group.

  20. A Deep Proper Motion Catalog Within the Sloan Digital Sky Survey Footprint. II. The White Dwarf Luminosity Function

    NASA Astrophysics Data System (ADS)

    Munn, Jeffrey A.; Harris, Hugh C.; von Hippel, Ted; Kilic, Mukremin; Liebert, James W.; Williams, Kurtis A.; DeGennaro, Steven; Jeffery, Elizabeth; Dame, Kyra; Gianninas, A.; Brown, Warren R.

    2017-01-01

    A catalog of 8472 white dwarf (WD) candidates is presented, selected using reduced proper motions from the deep proper motion catalog of Munn et al. Candidates are selected in the magnitude range 16< r< 21.5 over 980 square degrees, and 16< r< 21.3 over an additional 1276 square degrees, within the Sloan Digital Sky Survey (SDSS) imaging footprint. Distances, bolometric luminosities, and atmospheric compositions are derived by fitting SDSS ugriz photometry to pure hydrogen and helium model atmospheres (assuming surface gravities {log} {\\text{}}g=8). The disk white dwarf luminosity function (WDLF) is constructed using a sample of 2839 stars with 5.5< {M}{bol}< 17, with statistically significant numbers of stars cooler than the turnover in the luminosity function. The WDLF for the halo is also constructed, using a sample of 135 halo WDs with 5< {M}{bol}< 16. We find space densities of disk and halo WDs in the solar neighborhood of 5.5+/- 0.1× {10}-3 {{pc}}-3 and 3.5+/- 0.7× {10}-5 {{pc}}-3, respectively. We resolve the bump in the disk WDLF due to the onset of fully convective envelopes in WDs, and see indications of it in the halo WDLF as well.

  1. Erratum: ``The Luminosity Function of IRAS Point Source Catalog Redshift Survey Galaxies'' (ApJ, 587, L89 [2003])

    NASA Astrophysics Data System (ADS)

    Takeuchi, Tsutomu T.; Yoshikawa, Kohji; Ishii, Takako T.

    2004-05-01

    We have mentioned that we normalized the parameters for the luminosity function by the Hubble constant H0=100 km s-1 Mpc-1 however, for the characteristic luminosity L* we erroneously normalized it by H0=70 km s-1 Mpc-1. As a result, we have proposed wrong numerical factors for L*. In addition, there is a typographic error in the exponent of equation (6) of the published manuscript. Correct values are as follows: L*=(4.34+/-0.86)×108 h-2 [Lsolar] for equation (4), and L*=(2.50+/-0.44)×109 h-2 [Lsolar] and L*=(9.55+/-0.20)×108 h-2 [Lsolar] for equations (5) and (6), respectively. All the other parameters are correct. The errors have occurred only in the final conversion, and they do not affect our discussions and conclusions at all. We thank P. Ranalli for pointing out the errors.

  2. THE Pa{alpha} LUMINOSITY FUNCTION OF H II REGIONS IN NEARBY GALAXIES FROM HST/NICMOS

    SciTech Connect

    Liu Guilin; Calzetti, Daniela; Kennicutt, Robert C. Jr.; Schinnerer, Eva; Sofue, Yoshiaki; Komugi, Shinya; Egusa, Fumi; Scoville, Nicholas Z.

    2013-07-20

    The H II region luminosity function (LF) is an important tool for deriving the birthrates and mass distribution of OB associations and is an excellent tracer of the newly formed massive stars and associations. To date, extensive work (predominantly in H{alpha}) has been done from the ground, which is hindered by dust extinction and the severe blending of adjacent (spatially or in projection) H II regions. Reliably measuring the properties of H II regions requires a linear resolution <40 pc, but analyses satisfying this requirement have been done only in a handful of galaxies, so far. As the first space-based work using a galaxy sample, we have selected 12 galaxies from our HST/NICMOS Pa{alpha} survey and studied the LF and size distribution of H II regions both in individual galaxies and cumulatively, using a virtually extinction-free tracer of the ionizing photon rate. The high angular resolution and low sensitivity to diffuse emission of NICMOS also offer an advantage over ground-based imaging by enabling a higher degree of de-blending of the H II regions. We do not confirm the broken power-law LFs found in ground-based studies. Instead, we find that the LFs, both individual and co-added, follow a single power law dN(L)/dln L{proportional_to}L {sup -1}, are consistent with the mass function of star clusters in nearby galaxies, and are in agreement with the results of the existing analyses with Hubble Space Telescope (HST) data. The individual and co-added size distributions of H II regions are both roughly consistent with dN(D)/dln D{proportional_to}D {sup -3}, but the power-law scaling is probably contaminated by blended regions or complexes.

  3. The star formation rate distribution function of the local Universe

    NASA Astrophysics Data System (ADS)

    Bothwell, M. S.; Kennicutt, R. C.; Johnson, B. D.; Wu, Y.; Lee, J. C.; Dale, D.; Engelbracht, C.; Calzetti, D.; Skillman, E.

    2011-08-01

    We present total infrared (IR) and ultraviolet (UV) luminosity functions derived from large representative samples of galaxies at z˜ 0, selected at IR and UV wavelengths from the Imperial IRAS Faint Source Catalogue redshift data base (IIFSCz) catalogue, and the GALEX All-Sky Imaging Survey (AIS), respectively. We augment these with deep Spitzer and GALEX imaging of galaxies in the 11 Mpc Local Volume Legacy (LVL) Survey, allowing us to extend these luminosity functions to lower luminosities (˜106 L⊙), and providing good constraints on the slope of the luminosity function at the extreme faint end for the first time. Using conventional star formation prescriptions, we generate from our data the star formation rate (SFR) distribution function for the local Universe. We find that it has a Schechter form, the faint-end slope has a constant value (to the limits of our data) of α=-1.51 ± 0.08 and the ‘characteristic’ SFR ψ* is 9.2 M⊙ yr-1. We also show the distribution function of the SFR volume density; we then use this to calculate a value for the total SFR volume density at z˜ 0 of 0.025 ± 0.0016 M⊙ yr-1 Mpc-3, of which ˜20 per cent is occurring in starbursts. Decomposing the total star formation by infrared luminosity, it can be seen that 9 ± 1 per cent is due to LIRGs, and 0.7 ± 0.2 per cent is occurring in ULIRGs. By comparing UV and IR emission for galaxies in our sample, we also calculate the fraction of star formation occurring in dust-obscured environments, and examine the distribution of dusty star formation: we find a very shallow slope at the highly extincted end, which may be attributable to line-of-sight orientation effects as well as conventional internal extinction.

  4. The GALEX VIMOS-VLT Deep Survey Measurement of the Evolution of the 1500 Å Luminosity Function

    NASA Astrophysics Data System (ADS)

    Arnouts, S.; Schiminovich, D.; Ilbert, O.; Tresse, L.; Milliard, B.; Treyer, M.; Bardelli, S.; Budavari, T.; Wyder, T. K.; Zucca, E.; Le Fèvre, O.; Martin, D. C.; Vettolani, G.; Adami, C.; Arnaboldi, M.; Barlow, T.; Bianchi, L.; Bolzonella, M.; Bottini, D.; Byun, Y.-I.; Cappi, A.; Charlot, S.; Contini, T.; Donas, J.; Forster, K.; Foucaud, S.; Franzetti, P.; Friedman, P. G.; Garilli, B.; Gavignaud, I.; Guzzo, L.; Heckman, T. M.; Hoopes, C.; Iovino, A.; Jelinsky, P.; Le Brun, V.; Lee, Y.-W.; Maccagni, D.; Madore, B. F.; Malina, R.; Marano, B.; Marinoni, C.; McCracken, H. J.; Mazure, A.; Meneux, B.; Merighi, R.; Morrissey, P.; Neff, S.; Paltani, S.; Pellò, R.; Picat, J. P.; Pollo, A.; Pozzetti, L.; Radovich, M.; Rich, R. M.; Scaramella, R.; Scodeggio, M.; Seibert, M.; Siegmund, O.; Small, T.; Szalay, A. S.; Welsh, B.; Xu, C. K.; Zamorani, G.; Zanichelli, A.

    2005-01-01

    We present the first measurement of the galaxy luminosity function (LF) at 1500 Å in the range 0.2<=z<=1.2 based on Galaxy Evolution Explorer VIMOS-VLT Deep Survey observations (~1000 spectroscopic redshifts for galaxies with NUV<=24.5) and at higher z using existing data sets. Our main results are summarized as follows: (1) Luminosity evolution is observed with ΔM*~-2.0 mag between z=0 and z=1 and ΔM*~-1.0 mag between z=1 and z=3. This confirms that the star formation activity was significantly higher in the past. (2) The LF slopes vary in the range -1.2>=α>=-1.65, with a marginally significant hint of increase at higher z. (3) We split the sample in three rest-frame (B-I) intervals, providing an approximate spectral type classification: Sb-Sd, Sd-Irr, and unobscured starbursts. We find that the bluest class evolves less strongly in luminosity than the two other classes. On the other hand, their number density increases sharply with z (~15% in the local universe to ~55% at z~1), while that of the reddest classes decreases. The VIMOS-VLT Deep Survey observations have been obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile.

  5. THE INFLUENCE OF RED SPIRAL GALAXIES ON THE SHAPE OF THE LOCAL K-BAND LUMINOSITY FUNCTION

    SciTech Connect

    Bonne, Nicolas J.; Brown, Michael J. I.; Jones, Heath; Pimbblet, Kevin A.

    2015-02-01

    We have determined K-band luminosity functions for 13,325 local universe galaxies as a function of morphology and color (for K {sub tot} ≤ 10.75). Our sample is drawn from the Two Micron All Sky Survey Extended Source Catalog, with all sample galaxies having measured morphologies and distances (including 4219 archival redshift-independent distances). The luminosity function for our total sample is in good agreement with previous works, but is relatively smooth at faint magnitudes (due to bulk flow distance corrections). We investigated the differences due to morphological and color selection using 5417 sample galaxies with NASA Sloan Atlas optical colors and find that red spirals comprise 20%-50% of all spirals with –25 ≤ M{sub K}  < –20. Fainter than M{sub K} = –24, red spirals are as common as early types, explaining the different faint end slopes (α = –0.87 and –1.00 for red and early-types, respectively). While we find red spirals comprise more than 50% of all M{sub K}  < –25 spiral galaxies, they do not dominate the bright end of the overall red galaxy luminosity function, which is dominated by early-type galaxies. The brightest red spirals have ongoing star formation and those without are frequently misclassified as early-types. The faintest ones have an appearance and Sérsic indices consistent with faded disks, rather than true bulge-dominated galaxies.

  6. A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)

    NASA Technical Reports Server (NTRS)

    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 < 6.6. We find no significant evidence for Ly(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.

  7. A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)

    NASA Technical Reports Server (NTRS)

    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 < 6.6. We find no significant evidence for Ly(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.

  8. IMPACT OF H{sub 2}-BASED STAR FORMATION MODEL ON THE z {>=} 6 LUMINOSITY FUNCTION AND THE IONIZING PHOTON BUDGET FOR REIONIZATION

    SciTech Connect

    Jaacks, Jason; Thompson, Robert; Nagamine, Kentaro

    2013-04-01

    We present the results of a numerical study examining the effect of an H{sub 2}-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 H{sub 2}-SF model, we find good agreement with our previous results (non-H{sub 2} SF model) and observations at M{sub uv} {<=} -18. However, at M{sub uv} > -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 (M{sub uv}{sup t}) and subsequent slope ({beta}). We find that M{sub uv}{sup t} evolves from M{sub uv}{sup 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 M{sub uv} range that will be observable by James Webb Space Telescope. By integrating the SFRF, we determine that even though the H{sub 2}-SF model significantly reduces the number density of low-luminosity galaxies at M{sub uv} > -18, it does not suppress the total SFR density enough to affect the capability of SF to maintain reionization.

  9. A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations

    NASA Astrophysics Data System (ADS)

    Ferrarese, , Laura; Ford, Holland C.; Huchra, John; Kennicutt, Robert C., Jr.; Mould, Jeremy R.; Sakai, , Shoko; Freedman, Wendy L.; Stetson, Peter B.; Madore, Barry F.; Gibson, Brad K.; Graham, John A.; Hughes, Shaun M.; Illingworth, Garth D.; Kelson, Daniel D.; Macri, Lucas; Sebo, Kim; Silbermann, N. A.

    2000-06-01

    We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The database includes all data published as of 1999 July 15. The main strength of this compilation resides in the fact that all data are on a consistent and homogeneous system: all Cepheid distances are derived using the same calibration of the period-luminosity relation, the treatment of errors is consistent for all indicators, and measurements that are not considered reliable are excluded. As such, the database is ideal for comparing any of the distance indicators considered, or for deriving a Cepheid calibration to any secondary distance indicator, such as the Tully-Fisher relation, the Type Ia supernovae, or the fundamental plane for elliptical galaxies. This task has already been undertaken by Ferrarese et al., Sakai et al., Kelson et al., and Gibson et al. Specifically, the database includes (1) Cepheid distances, extinctions, and metallicities; (2) reddened apparent λ5007 Å magnitudes of the PNLF cutoff; (3) reddened apparent magnitudes and colors of the turnover of the GCLF (in both the V and B bands); (4) reddened apparent magnitudes of the TRGB (in the I band) and V-I colors at 0.5 mag fainter than the TRGB; and (5) reddened apparent surface brightness fluctuation magnitudes measured in Kron-Cousin I, K', and Kshort, and using the F814W filter with the Hubble Space Telescope (HST) WFPC2. In addition, for every galaxy in the database we give reddening estimates from IRAS/DIRBE as well as H I maps, J2000 coordinates, Hubble and T-type morphological classification, apparent total magnitude in B, and systemic velocity.

  10. The mass, luminosity and mass-loss rate of the donor of the V1487 Aql/GRS 1915+105 binary system

    NASA Astrophysics Data System (ADS)

    Ziółkowski, Janusz; Zdziarski, Andrzej A.

    2017-08-01

    The donor in the microquasar GRS 1915+105 is a low-mass giant. Such a star consists of a degenerate helium core and a hydrogen-rich envelope. Both components are separated by a hydrogen-burning shell. The structure of such an object is relatively simple and easy to model. Making use of the observational constraints on the luminosity and the radius of the donor, we constrain the mass of this star with evolutionary models. We find a very good agreement between the constraints from those models and from the observed rotational broadening and the near-infrared magnitude. Combining the constraints, we find solutions with stripped giants of mass ≥0.28 M⊙ and of the spectral class K5 III, independent of the distance to the system, and a distance-dependent upper limit, ≲1 M⊙. We also calculate the average mass transfer rate and the duty cycle of the system as a function of the donor mass. This rate is much below the critical rate (at which the system would become persistent), and the duty cycle is less than 20 per cent.

  11. Optical and Radio Properties of QSOS as a Function of Absolute Luminosity.

    NASA Astrophysics Data System (ADS)

    Pica, Andrew Joseph

    1982-03-01

    Photometric data for nearly 250 quasars, BL Lacertids, and active galaxies have been obtained at the Rosemary Hill Observatory during a continuous 13-year monitoring program. Long-term optical records for 130 of these sources are employed in an effort to assess the physical and cosmological properties of quasi-stellar objects. Photographic P and B magnitudes were obtained with the 76- and 46-cm telescopes at Rosemary Hill. Corrections for galactic absorption, emission lines, and the K-term are applied to the raw data yielding monochromatic flux densities at a standard emitted wavelength of 2500 (ANGSTROM). Long -term light curves are compiled for all objects and 3 levels of activity are determined for each individual source. The MEAN, BASE, and MAX brightness levels are then used to study QSOs in their average, quiescent, and active phases, respectively. Absolute intrinsic luminosities of all sources in the sample are computed from the monochromatic flux densities based on relativistic cosmological models. Radio -emitting quasars, radio-quiet QSOs, and active galaxies fall into 3 distinct groups and are examined separately. The cosmological properties of QSOs are studied by plotting apparent magnitude vs. redshift, the so-called Hubble diagram. Scatter in the diagram due to variability is substantially reduced by plotting log z vs. the MEAN, BASE, and MAX flux densities. The brightest QSOs at each redshift are then chosen as "standard candles" in an effort to determine if quasars obey Hubble's law for expanding universe. It is found that they fit the Hubble relation quite well if certain selection effects are accounted for. Other evidence for the cosmological origin of QSOs is briefly discussed. Variability provides a test as to whether individual quasars are essentially multiple in nature (the "Christmas Tree" model), or are single coherent sources (such as a massive black hole). The amplitude of variability vs. absolute luminosity relation is used to discriminate

  12. Herschel-ATLAS Galaxy Counts and High-redshift Luminosity Functions: The Formation of Massive Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Lapi, A.; González-Nuevo, J.; Fan, L.; Bressan, A.; De Zotti, G.; Danese, L.; Negrello, M.; Dunne, L.; Eales, S.; Maddox, S.; Auld, R.; Baes, M.; Bonfield, D. G.; Buttiglione, S.; Cava, A.; Clements, D. L.; Cooray, A.; Dariush, A.; Dye, S.; Fritz, J.; Herranz, D.; Hopwood, R.; Ibar, E.; Ivison, R.; Jarvis, M. J.; Kaviraj, S.; López-Caniego, M.; Massardi, M.; Michałowski, M. J.; Pascale, E.; Pohlen, M.; Rigby, E.; Rodighiero, G.; Serjeant, S.; Smith, D. J. B.; Temi, P.; Wardlow, J.; van der Werf, P.

    2011-11-01

    Exploiting the Herschel Astrophysical Terahertz Large Area Survey Science Demonstration Phase survey data, we have determined the luminosity functions (LFs) at rest-frame wavelengths of 100 and 250 μm and at several redshifts z >~ 1, for bright submillimeter galaxies with star formation rates (SFRs) >~ 100 M ⊙ yr-1. We find that the evolution of the comoving LF is strong up to z ≈ 2.5, and slows down at higher redshifts. From the LFs and the information on halo masses inferred from clustering analysis, we derived an average relation between SFR and halo mass (and its scatter). We also infer that the timescale of the main episode of dust-enshrouded star formation in massive halos (M H >~ 3 × 1012 M ⊙) amounts to ~7 × 108 yr. Given the SFRs, which are in the range of 102-103 M ⊙ yr-1, this timescale implies final stellar masses of the order of 1011-1012 M ⊙. The corresponding stellar mass function matches the observed mass function of passively evolving galaxies at z >~ 1. The comparison of the statistics for submillimeter and UV-selected galaxies suggests that the dust-free, UV bright phase is >~ 102 times shorter than the submillimeter bright phase, implying that the dust must form soon after the onset of star formation. Using a single reference spectral energy distribution (SED; the one of the z ≈ 2.3 galaxy SMM J2135-0102), our simple physical model is able to reproduce not only the LFs at different redshifts >1 but also the counts at wavelengths ranging from 250 μm to ≈1 mm. Owing to the steepness of the counts and their relatively broad frequency range, this result suggests that the dispersion of submillimeter SEDs of z > 1 galaxies around the reference one is rather small. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  13. The joint far-infrared-optical luminosity function for spiral galaxies and data for the Abell 400 and Cancer clusters

    NASA Technical Reports Server (NTRS)

    Corbelli, Edvige; Salpeter, Edwin E.; Dickey, John M.

    1991-01-01

    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.

  14. The 2.4 μm Galaxy Luminosity Function As Measured Using WISE. I. Measurement Techniques

    NASA Astrophysics Data System (ADS)

    Lake, S. E.; Wright, E. L.; Tsai, C.-W.; Lam, A.

    2017-04-01

    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 (LFs). Utilizing the back catalog with new photometric surveys to maximum efficiency requires modeling the color selection bias imposed on the 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 LF, {{Φ }}(L), over the space of all spectra: the spectro-luminosity functional, {{\\Psi }}[{L}ν ]. It is, therefore, the first estimator capable of simultaneously analyzing multiple redshift surveys in a consistent way. We also propose a new way of parametrizing the evolution of the classic Schechter function parameters, L ⋆ and ϕ ⋆, that improves both the physical realism and statistical performance of the model. The techniques derived in this paper are used in a companion paper by Lake et al. to measure the LF of galaxies at the rest-frame wavelength of 2.4 μ {{m}} using the Widefield Infrared Survey Explorer (WISE).

  15. THE VERY FAINT END OF THE UV LUMINOSITY FUNCTION OVER COSMIC TIME: CONSTRAINTS FROM THE LOCAL GROUP FOSSIL RECORD

    SciTech Connect

    Weisz, Daniel R.; Johnson, Benjamin D.; Conroy, Charlie

    2014-10-10

    We present a new technique to estimate the evolution of the very faint end of the UV luminosity function (LF) out to z ∼ 5. Measured star formation histories (SFHs) from the fossil record of Local Group (LG) galaxies are used to reconstruct the LF down to M {sub UV} ∼–5 at z ∼ 5 and M {sub UV} ∼–1.5 at z < 1. Such faint limits are well beyond the current observational limits and are likely to remain beyond the limits of next-generation facilities. The reconstructed LFs, when combined with direct measurements of the LFs at higher luminosity, are well-fit by a standard Schechter function with no evidence of a break to the faintest limits probed by this technique. The derived faint-end slope, α, steepens from ≈ – 1.2 at z < 1 to ≈ – 1.6 at 4 < z < 5. We test the effects of burstiness in the SFHs and find the recovered LFs to be only modestly affected. Incompleteness corrections for the faintest LG galaxies and the (unlikely) possibility of significant luminosity-dependent destruction of dwarf galaxies between high redshift and the present epoch are important uncertainties. These and other uncertainties can be mitigated with more detailed modeling and future observations. The reconstructed faint end LF from the fossil record can therefore be a powerful and complementary probe of the high-redshift faint galaxies believed to play a key role in the reionization of the universe.

  16. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). I. The UV luminosity function of the central 12 sq. deg

    NASA Astrophysics Data System (ADS)

    Boselli, A.; Boissier, S.; Heinis, S.; Cortese, L.; Ilbert, O.; Hughes, T.; Cucciati, O.; Davies, J.; Ferrarese, L.; Giovanelli, R.; Haynes, M. P.; Baes, M.; Balkowski, C.; Brosch, N.; Chapman, S. C.; Charmandaris, V.; Clemens, M. S.; Dariush, A.; De Looze, I.; di Serego Alighieri, S.; Duc, P.-A.; Durrell, P. R.; Emsellem, E.; Erben, T.; Fritz, J.; Garcia-Appadoo, D. A.; Gavazzi, G.; Grossi, M.; Jordán, A.; Hess, K. M.; Huertas-Company, M.; Hunt, L. K.; Kent, B. R.; Lambas, D. G.; Lançon, A.; MacArthur, L. A.; Madden, S. C.; Magrini, L.; Mei, S.; Momjian, E.; Olowin, R. P.; Papastergis, E.; Smith, M. W. L.; Solanes, J. M.; Spector, O.; Spekkens, K.; Taylor, J. E.; Valotto, C.; van Driel, W.; Verstappen, J.; Vlahakis, C.; Vollmer, B.; Xilouris, E. M.

    2011-04-01

    The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering ~40 sq. deg in the far UV (FUV, λeff = 1539 Å, Δλ = 442 Å) and ~120 sq. deg in the near UV (NUV, λeff = 2316 Å, Δλ = 1060 Å). The goal of the survey is to study the ultraviolet (UV) properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and regardless of prior knowledge of their star formation activity. The UV data will be combined with those in other bands (optical: NGVS; far-infrared - submm: HeViCS; HI: ALFALFA) and with our multizone chemo-spectrophotometric models of galaxy evolution to make a complete and exhaustive study of the effects of the environment on the evolution of galaxies in high density regions. We present here the scientific objectives of the survey, describing the observing strategy and briefly discussing different data reduction techniques. Using UV data already in-hand for the central 12 sq. deg we determine the FUV and NUV luminosity functions of the Virgo cluster core for all cluster members and separately for early- and late-type galaxies and compare it to the one obtained in the field and other nearby clusters (Coma, A1367). This analysis shows that the FUV and NUV luminosity functions of the core of the Virgo clusters are flatter (α ~ -1.1) than those determined in Coma and A1367. We discuss the possible origin of this difference. Table 1 is only available in electronic form at http://www.aanda.org

  17. The luminosity function of star clusters in 20 star-forming galaxies based on Hubble legacy archive photometry

    SciTech Connect

    Whitmore, Bradley C.; Bowers, Ariel S.; Lindsay, Kevin; Ansari, Asna; Evans, Jessica; Chandar, Rupali; Larsen, Soeren

    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 the number

  18. The bright end of the exo-Zodi luminosity function: disc evolution and implications for exo-Earth detectability

    NASA Astrophysics Data System (ADS)

    Kennedy, G. M.; Wyatt, M. C.

    2013-08-01

    We present the first characterisation of the 12 μm warm dust (`exo-Zodi') luminosity function around Sun-like stars, focusing on the dustiest systems that can be identified by the WISE mission. We use the sample of main-sequence stars observed by Hipparcos within 150 pc as an unbiased sample, and report the detection of six new warm dust candidates. The ages of five of these new sources are unknown, meaning that they may be sites of terrestrial planet formation or rare analogues of other old warm dust systems. We show that the dustiest old (>Gyr) systems such as BD+20 307 are 1 in 10 000 occurrences. Bright warm dust is much more common around young (<120 Myr) systems, with a ˜1 per cent occurrence rate. We show that a two component in situ model, where all stars have initially massive warm discs 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 have only initially massive warm discs, then these would not be visible at Gyr ages, and random collisions on the main sequence are too infrequent to explain the high disc occurrence rate for young stars. That is, neither of the components can explain the observations on their own. Despite these conclusions, we cannot rule out an alternative dynamical model in which comets are scattered in from outer regions because the distribution of systems with the appropriate dynamics is unknown. Our in situ model predicts that the fraction of stars with exo-Zodi bright enough to cause problems for future exo-Earth imaging attempts is at least roughly 10 per cent, and is higher for populations of stars younger than a few Gyr. This prediction of roughly 10 per cent also applies to old stars because bright systems like BD+20 307 imply a population of fainter systems that were once bright, but are now decaying through fainter levels. Our prediction should be strongly tested by the Large Binocular

  19. The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability

    NASA Astrophysics Data System (ADS)

    Kennedy, G. M.; Wyatt, M. C.

    2014-01-01

    This contribution summarises the first characterisation of the 12 μm warm dust (``exo-Zodi'') luminosity function around Sun-like stars, focussing on the dustiest systems that can be identified by the WISE mission (Kennedy & Wyatt 2013). We use the sample of main-sequence stars observed by Hipparcos within 150pc as an unbiased sample, and report the detection of six new warm dust candidates. The ages of five of these new sources are unknown, meaning that they may be sites of terrestrial planet formation or rare analogues of other old warm dust systems. We show that the dustiest old (> Gyr) systems such as BD+20 307 are 1 in 10,000 occurrences. Bright warm dust is much more common around young (<120 Myr) 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 cannot rule out an alternative dynamical model in which comets are scattered in from outer regions because the distribution of systems with the appropriate dynamics is unknown. Our in situ model predicts that the fraction of stars with exo-Zodi bright enough to cause problems for future exo-Earth imaging attempts is at least roughly 10%, and is higher for populations of stars younger than a few Gyr. This prediction of roughly 10% also applies to old stars because bright systems like BD+20 307 imply a population of fainter systems that were once bright, but are now decaying through fainter levels. Our prediction should be strongly tested by the Large Binocular

  20. The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability

    NASA Astrophysics Data System (ADS)

    Kennedy, Grant; Wyatt, Mark

    2013-07-01

    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 the WISE mission. We use the sample of main-sequence stars observed by Hipparcos within 150pc as an unbiased sample, and report the detection of six new warm dust candidates. The ages of five of these new sources are unknown, meaning that they may be sites of terrestrial planet formation or rare analogues of other old warm dust systems. We show that the dustiest old (>Gyr) systems such as BD+20 307 are 1 in 10,000 occurrences. Bright warm dust is much 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 cannot rule out an alternative dynamical model in which comets are scattered in from outer regions because the distribution of systems with the appropriate dynamics is unknown. Our in situ model predicts that the fraction of stars with exo-Zodi bright enough to cause problems for future exo-Earth imaging attempts is at least roughly 10%, and is higher for populations of stars younger than a few Gyr. This prediction of roughly 10% also applies to old stars because bright systems like BD+20 307 imply a population of fainter systems that were once bright, but are now decaying through fainter levels. Our prediction should be strongly tested by the Large Binocular Telescope Interferometer, which will provide

  1. The Origin of Dwarf Galaxies in Clusters: The Faint-End Slope of Abell 85 Galaxy Luminosity Function

    NASA Astrophysics Data System (ADS)

    Agulli, I.; Aguerri, J. A. L.; Barrena, R.; Diaferio, A.; Sánchez-Janssen, R.

    2016-10-01

    Dwarf galaxies (Mb>-18) are important because of their cosmological interest as tests of hierarchical theories. The formation of these galaxies is still an open question but red dwarf galaxies are preferentially located in high density environments, indicating that they are end-products of galaxy transformations in clusters. Deep spectroscopic studies of galaxy clusters are needed to put some constraints on dwarf galaxy formation and evolution. We have observed and analyzed Abell 85, a nearby (z = 0.055) and massive cluster down to M*+6, using the MOS instruments VIMOS@VLT and AF2@WHT. The first and powerful tool to study the characteristics of galaxies and compare with different density environments is the galaxy luminosity function. The comparison of the results for Abell 85 with literature outcomes for clusters and field, allows us to conclude that, at least for this cluster, the environment plays a major role in the nature of the faint-end galaxies, transforming blue dwarfs in the field into red ones in the cluster, but not in the formation of the luminosity function slope.

  2. The VIMOS VLT Deep Survey. Evolution of the luminosity functions by galaxy type up to z = 1.5 from first epoch data

    NASA Astrophysics Data System (ADS)

    Zucca, E.; Ilbert, O.; Bardelli, S.; Tresse, L.; Zamorani, G.; Arnouts, S.; Pozzetti, L.; Bolzonella, M.; McCracken, H. J.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Picat, J. P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Paltani, S.; Pellò, R.; Pollo, A.; Radovich, M.; Bondi, M.; Bongiorno, A.; Busarello, G.; Cucciati, O.; Gregorini, L.; Lamareille, F.; Mathez, G.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.

    2006-09-01

    From first epoch observations of the VIMOS VLT Deep Survey (VVDS) we have derived luminosity functions for galaxy samples selected by spectral type out to z=1.5. With the VVDS we are able to investigate within the same sample the evolution of the type dependent luminosity function selected in several rest-frame bands over 70% of the age of the Universe. The simple I_AB=24 VVDS magnitude limit is significantly fainter than other complete spectroscopic surveys and allows the determination of the faint end slope of the luminosity function with unprecedented accuracy. Galaxies have been classified in four spectral types, from early type to irregular galaxies, using their colours and redshift. Luminosity functions have been computed in the U, B, V, R and I rest frame bands for each type, in redshift bins from z=0.05 to z=1.5. In all the considered rest frame bands, we find a significant steepening of the luminosity function from early to late types. The characteristic luminosity M* of the Schechter function is significantly fainter for late type galaxies and this difference between types increases in the redder bands. For each spectral type we find a brightening of M* with increasing redshift, ranging from ≲0.5 mag for early type galaxies to ~1 mag for the latest type galaxies, while the slope of the luminosity function of each spectral type is consistent with being redshift-independent. The luminosity function of early type galaxies is consistent with passive evolution up to z˜ 1.1, whilst the number of bright (MB_AB< -20) early type galaxies has decreased by ~40% from z˜ 0.3 to z ˜ 1.1. The normalisation of the luminosity function of latest type galaxies evolves strongly with redshift with an increase of more than a factor 2 from z˜ 0.3 to z˜ 1.3: the density of bright (MB_AB< -20) late type galaxies in the same redshift range increases of a factor ~6.6. These results indicate a strong type-dependent evolution and identifies the latest spectral types as

  3. Bright end of the luminosity function of high-mass X-ray binaries: contributions of hard, soft and supersoft sources

    NASA Astrophysics Data System (ADS)

    Sazonov, S.; Khabibullin, I.

    2017-04-01

    Using a spectral analysis of bright Chandra X-ray sources located in 27 nearby galaxies and maps of star-formation rate (SFR) and interstellar medium surface densities for these galaxies, we constructed the intrinsic X-ray luminosity function (XLF) of luminous high-mass X-ray binaries (HMXBs), taking into account absorption effects and the diversity of HMXB spectra. The XLF per unit SFR can be described by a power-law dN/dlog LX,unabs ≈ 2.0(LX,unabs/1039 erg s-1)-0.6 (M⊙ yr-1)-1 from LX,unabs = 1038 to 1040.5 erg s-1, where LX,unabs is the unabsorbed luminosity at 0.25-8 keV. The intrinsic number of luminous HMXBs per unit SFR is a factor of ∼2.3 larger than the observed number reported before. The intrinsic XLF is composed of hard, soft and supersoft sources (defined here as those with the 0.25-2 keV to 0.25-8 keV flux ratio of <0.6, 0.6-0.95 and >0.95, respectively) in ∼ 2:1:1 proportion. We also constructed the intrinsic HMXB XLF in the soft X-ray band (0.25-2 keV). Here, the numbers of hard, soft and supersoft sources prove to be nearly equal. The cumulative present-day 0.25-2 keV emissivity of HMXBs with luminosities between 1038 and 1040.5 erg s-1 is ∼5 × 1039 erg s-1(M⊙ yr-1)-1, which may be relevant for studying the X-ray preheating of the early Universe.

  4. Constraining the Warm Dark Matter Particle Mass through Ultra-deep UV Luminosity Functions at z=2

    NASA Astrophysics Data System (ADS)

    Menci, N.; Sanchez, N. G.; Castellano, M.; Grazian, A.

    2016-02-01

    We compute the mass function of galactic dark matter halos for different values of the warm dark matter (WDM) particle mass mX and compare it with the number density of ultra-faint galaxies derived from the deepest UV luminosity function available so far at redshift z ≈ 2. The magnitude limit MUV = -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 ˜109 M⊙. This allowed for an efficient discrimination among predictions for different mX which turn out to be in practice independent of the star formation efficiency η adopted to associate the observed UV luminosities of galaxies to the corresponding dark matter halo masses. Adopting a conservative approach to take into account the existing theoretical uncertainties in the galaxy halo mass function, we obtain a robust limit mX ≥ 1.8 keV for the mass of thermal relic WDM particles when comparing with the measured abundance of the faintest galaxies, while mX ≥ 1.5 keV is obtained when we compare with the Schechter fit to the observed luminosity function. The corresponding lower limit for sterile neutrinos depends on the modeling of the production mechanism; for instance msterile ≳ 4 keV holds for the Shi-Fuller mechanism. We discuss the impact of observational uncertainties on the above bound on mX. In the cold dark matter (CDM) limit {m}X\\gg 1 {{keV}} we recover the generic CDM result that very inefficient star formation efficiency is required to match the observed galaxy abundances. As a baseline for comparison with forthcoming observational results from the Hubble Space Telescope Frontier Field project, we provide predictions for the number density of faint galaxies with MUV = -13 for different values of the WDM particle mass and of the star formation efficiency η, which are valid up to z ≈ 4.

  5. THE WYOMING SURVEY FOR H{alpha}. II. H{alpha} LUMINOSITY FUNCTIONS AT z{approx} 0.16, 0.24, 0.32, AND 0.40

    SciTech Connect

    Dale, Daniel A.; Cook, David O.; Moore, Carolynn A.; Staudaher, Shawn M.; Barlow, Rebecca J.; Cohen, Seth A.; Johnson, L. Clifton; Kattner, ShiAnne M.; Schuster, Micah D.

    2010-04-01

    The Wyoming Survey for H{alpha}, or WySH, is a large-area, ground-based imaging survey for H{alpha}-emitting galaxies at redshifts of z {approx} 0.16, 0.24, 0.32, and 0.40. The survey spans up to 4 deg{sup 2} in a set of fields of low Galactic cirrus emission, using twin narrowband filters at each epoch for improved stellar continuum subtraction. H{alpha} luminosity functions are presented for each {delta}z {approx} 0.02 epoch based on a total of nearly 1200 galaxies. These data clearly show an evolution with look-back time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the incompleteness- and extinction-corrected H{alpha} luminosity functions indicate star formation rates per comoving volume of 0.010, 0.013, 0.020, 0.022 h {sub 70} M {sub sun} yr{sup -1} Mpc{sup -3} at z {approx} 0.16, 0.24, 0.32, and 0.40, respectively. Combined statistical and systematic measurement uncertainties are on the order of 25%, while the effects of cosmic variance are at the 20% level. The bulk of this evolution is driven by changes in the characteristic luminosity L {sub *} of the H{alpha} luminosity functions, with L {sub *} for the earlier two epochs being a factor of 2 larger than L {sub *} at the latter two epochs; it is more difficult with this data set to decipher systematic evolutionary differences in the luminosity function amplitude and faint-end slope. Coupling these results with a comprehensive compilation of results from the literature on emission line surveys, the evolution in the cosmic star formation rate density over 0 {approx}< z {approx}< 1.5 is measured.

  6. Current Status of the Hot White Dwarf Luminosity Function and non-DA to DA Ratio from SDSS Data

    NASA Astrophysics Data System (ADS)

    Krzesinski, J.; Stachowski, G.

    2017-03-01

    Recent advances in the determination of the hot white dwarf (WD) luminosity function have reached the point where we have good agreement between the observed and theoretical DA and non-DA LFs for WDs from SDSS DR4. The main progress in calculation of the DA LF was obtained when the WD sample was restricted to only carbon-oxygen core WDs. However, one remaining effect which could influence the LF and the non-DA to DA ratio is the difference in visibility of helium- and hydrogen-atmosphere WDs in a magnitude-limited sample. In this work we explore this effect for the SDSS g filter as a function of effective temperature, as well as make an attempt to evaluate data relevant to the WD sample and LFs from more recent data releases of the SDSS.

  7. Galaxy And Mass Assembly (GAMA): the dependence of the galaxy luminosity function on environment, redshift and colour

    NASA Astrophysics Data System (ADS)

    McNaught-Roberts, Tamsyn; Norberg, Peder; Baugh, Carlton; Lacey, Cedric; Loveday, J.; Peacock, J.; Baldry, I.; Bland-Hawthorn, J.; Brough, S.; Driver, Simon P.; Robotham, A. S. G.; Vázquez-Mata, J. A.

    2014-12-01

    We use 80 922 galaxies in the Galaxy And Mass Assembly (GAMA) survey to measure the galaxy luminosity function (LF) in different environments over the redshift range 0.04 < z < 0.26. The depth and size of GAMA allows us to define samples split by colour and redshift to measure the dependence of the LF on environment, redshift and colour. We find that the LF varies smoothly with overdensity, consistent with previous results, with little environmental dependent evolution over the last 3 Gyr. The modified GALFORM model predictions agree remarkably well with our LFs split by environment, particularly in the most overdense environments. The LFs predicted by the model for both blue and red galaxies are consistent with GAMA for the environments and luminosities 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 galaxies predicted in underdense regions could be due to the implementation of AGN feedback not being sufficiently effective in the lower mass haloes.

  8. A Complete Sample of Bright Swift Long Gamma-Ray Bursts. I. Sample Presentation, Luminosity Function and Evolution

    NASA Astrophysics Data System (ADS)

    Salvaterra, R.; Campana, S.; 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.

    2012-04-01

    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, 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 (δ l = 2.3 ± 0.6) or in density (δ 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.

  9. PROBING THE FAINT END OF THE QUASAR LUMINOSITY FUNCTION AT z{approx} 4 IN THE COSMOS FIELD

    SciTech Connect

    Ikeda, H.; Nagao, T.; Matsuoka, K.; Ideue, Y.; Taniguchi, Y.; Shioya, Y.; Trump, J. R.; Comastri, A.; Enoki, M.; Koekemoer, A. M.; Morokuma, T.; Murayama, T.; Saito, T.; Silverman, J. D.; Salvato, M.; Schinnerer, E.

    2011-02-20

    We searched for quasars that are {approx}3 mag fainter than the SDSS quasars in the redshift range 3.7 {approx}< z {approx}< 4.7 in the COSMOS field to constrain the faint end of the quasar luminosity function (QLF). Using optical photometric data, we selected 31 quasar candidates with 22 < i' < 24 at z {approx} 4. We obtained optical spectra for most of these candidates using FOCAS on the Subaru telescope and identified eight low-luminosity quasars at z {approx} 4. In order to derive the QLF based on our spectroscopic follow-up campaign, we estimated the photometric completeness of our quasar survey through detailed Monte Carlo simulations. Our QLF at z {approx} 4 has a much shallower faint-end slope ({beta} = -1.67{sup +0.11}{sub -0.17}) than that obtained by other recent surveys in the same redshift. Our result is consistent with the scenario of downsizing evolution of active galactic nuclei inferred by recent optical and X-ray quasar surveys at lower redshifts.

  10. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. III. BRIGHTNESS DISTRIBUTIONS AND LUMINOSITY FUNCTIONS OF OPTICAL AFTERGLOWS

    SciTech Connect

    Wang Xianggao; Liang Enwei; Li Liang; Lu Ruijing; Wei Jianyan; Zhang Bing

    2013-09-10

    We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t = 10{sup 2} s, 10{sup 3} s, and 1 hr) for the optical light curves of a sample of 93 GRBs (the global sample) and for sub-samples with an afterglow onset bump or a shallow decay segment. For the onset sample and shallow decay sample we also present the brightness distribution at the peak time t{sub p} and break time t{sub b}, respectively. All the distributions can be fit with Gaussian functions. We further perform Monte Carlo simulations to infer the luminosity function of GRB optical emission at the rest-frame time 10{sup 3} s, t{sub p}, and t{sub b}. Our results show that a single power-law luminosity function is adequate to model the data with indices -1.40 {+-} 0.10, -1.06 {+-} 0.16, and -1.54 {+-} 0.22. Based on the derived rest-frame 10{sup 3} s luminosity function, we generate the intrinsic distribution of the R-band apparent magnitude M{sub R} at the observed time 10{sup 3} s post-trigger, which peaks at M{sub R} = 22.5 mag. The fraction of GRBs whose R-band magnitude is fainter than 22 mag and 25 mag and at the observer time 10{sup 3} s are {approx}63% and {approx}25%, respectively. The detection probabilities of the optical afterglows with ground-based robotic telescopes and the UV-Optical Telescope on board Swift are roughly consistent with that inferred from this intrinsic M{sub R} distribution, indicating that the variations of the dark GRB fraction among the samples with different telescopes may be due to the observational selection effect, although the existence of an intrinsically dark GRB population cannot be ruled out.

  11. M dwarfs in the Local Milky Way: The Field Low-Mass Stellar Luminosity and Mass Functions

    SciTech Connect

    Bochanski, Jr, John J.

    2008-01-01

    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.

  12. Power spectrum, correlation function, and tests for luminosity bias in the CfA redshift survey

    NASA Astrophysics Data System (ADS)

    Park, Changbom; Vogeley, Michael S.; Geller, Margaret J.; Huchra, John P.

    1994-08-01

    We describe and apply a method for directly computing the power spectrum for the galaxy distribution in the extension of the Center for Astrophysics Redshift Survey. Tests show that our technique accurately reproduces the true power spectrum for k greater than 0.03 h Mpc-1. The dense sampling and large spatial coverage of this survey allow accurate measurement of the redshift-space power spectrum on scales from 5 to approximately 200 h-1 Mpc. The power spectrum has slope n approximately equal -2.1 on small scales (lambda less than or equal 25 h-1 Mpc) and n approximately -1.1 on scales 30 less than lambda less than 120 h-1 Mpc. On larger scales the power spectrum flattens somewhat, but we do not detect a turnover. Comparison with N-body simulations of cosmological models shows that an unbiased, open universe CDM model (OMEGA h = 0.2) and a nonzero cosmological constant (CDM) model (OMEGA h = 0.24, lambdazero = 0.6, b = 1.3) match the CfA power spectrum over the wavelength range we explore. The standard biased CDM model (OMEGA h = 0.5, b = 1.5) fails (99% significance level) because it has insufficient power on scales lambda greater than 30 h-1 Mpc. Biased CDM with a normalization that matches the Cosmic Microwave Background (CMB) anisotropy (OMEGA h = 0.5, b = 1.4, sigma8 (mass) = 1) has too much power on small scales to match the observed galaxy power spectrum. This model with b = 1 matches both Cosmic Background Explorer Satellite (COBE) and the small-scale power spect rum but has insufficient power on scales lambda approximately 100 h-1 Mpc. We derive a formula for the effect of small-scale peculiar velocities on the power spectrum and combine this formula with the linear-regime amplification described by Kaiser to compute an estimate of the real-space power spectrum. Two tests reveal luminosity bias in the galaxy distribution: First, the amplitude of the power spectrum is approximately 40% larger for the brightest 50% of galaxies in volume-limited samples that

  13. Power spectrum, correlation function, and tests for luminosity bias in the CfA redshift survey

    NASA Technical Reports Server (NTRS)

    Park, Changbom; Vogeley, Michael S.; Geller, Margaret J.; Huchra, John P.

    1994-01-01

    We describe and apply a method for directly computing the power spectrum for the galaxy distribution in the extension of the Center for Astrophysics Redshift Survey. Tests show that our technique accurately reproduces the true power spectrum for k greater than 0.03 h Mpc(exp -1). The dense sampling and large spatial coverage of this survey allow accurate measurement of the redshift-space power spectrum on scales from 5 to approximately 200 h(exp -1) Mpc. The power spectrum has slope n approximately equal -2.1 on small scales (lambda less than or equal 25 h(exp -1) Mpc) and n approximately -1.1 on scales 30 less than lambda less than 120 h(exp -1) Mpc. On larger scales the power spectrum flattens somewhat, but we do not detect a turnover. Comparison with N-body simulations of cosmological models shows that an unbiased, open universe CDM model (OMEGA h = 0.2) and a nonzero cosmological constant (CDM) model (OMEGA h = 0.24, lambda(sub zero) = 0.6, b = 1.3) match the CfA power spectrum over the wavelength range we explore. The standard biased CDM model (OMEGA h = 0.5, b = 1.5) fails (99% significance level) because it has insufficient power on scales lambda greater than 30 h(exp -1) Mpc. Biased CDM with a normalization that matches the Cosmic Microwave Background (CMB) anisotropy (OMEGA h = 0.5, b = 1.4, sigma(sub 8) (mass) = 1) has too much power on small scales to match the observed galaxy power spectrum. This model with b = 1 matches both Cosmic Background Explorer Satellite (COBE) and the small-scale power spect rum but has insufficient power on scales lambda approximately 100 h(exp -1) Mpc. We derive a formula for the effect of small-scale peculiar velocities on the power spectrum and combine this formula with the linear-regime amplification described by Kaiser to compute an estimate of the real-space power spectrum. Two tests reveal luminosity bias in the galaxy distribution: First, the amplitude of the pwer spectrum is approximately 40% larger for the brightest

  14. MUSE deep-fields: the Ly α luminosity function in the Hubble Deep Field-South at 2.91 < z < 6.64

    NASA Astrophysics Data System (ADS)

    Drake, Alyssa B.; Guiderdoni, Bruno; Blaizot, Jérémy; Wisotzki, Lutz; Herenz, Edmund Christian; Garel, Thibault; Richard, Johan; Bacon, Roland; Bina, David; Cantalupo, Sebastiano; Contini, Thierry; den Brok, Mark; Hashimoto, Takuya; Marino, Raffaella Anna; Pelló, Roser; Schaye, Joop; Schmidt, Kasper B.

    2017-10-01

    We present the first estimate of the Ly α 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 α 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 α fluxes can be underestimated by a factor of 2 or more via traditional methods, and so we undertake a careful assessment of each object's Ly α 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 α luminosity function between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find that the luminosity function is higher than many number densities reported in the literature by a factor of 2-3, although our result is consistent at the 1σ level with most of these studies. Our observed luminosity function is also in good agreement with predictions from semi-analytic models, and shows no evidence for strong evolution between the high- and low-redshift halves of the data. We demonstrate that one's approach to Ly α flux estimation does alter the observed luminosity function, and caution that accurate flux assessments will be crucial in measurements of the faint-end slope. This is a pilot study for the Ly α luminosity function in the MUSE deep-fields, to be built on with data from the Hubble Ultra Deep Field that will increase the size of our sample by almost a factor of 10.

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

    NASA Technical Reports Server (NTRS)

    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

  16. Errata: A Wide-Field Multicolor Survey for High-Redshift Quasars, Z >= 2.2. III. The Luminosity Function

    NASA Astrophysics Data System (ADS)

    Warren, Stephen J.; Hewett, Paul C.; Osmer, Patrick S.

    1995-01-01

    In the paper "A Wide-Field Multicolor Survey for High-Redshift Quasars, z >= 2.2. III. The Luminosity Function" by Stephen. Warren, Paul C. Hewett and Patrick S. Osmer (ApJ, 421,412 [1994]), two equations should be corrected: On page 419, column one, line 11, the expression following the words "the error,, should have an opening parenthesis just before the integral sign, to read: [{SIGMA} 1/({integral} ρ(z)dV_a_)^2^]^1/2^. On page 421, equation (15) is missing the asterisk (*) in the M_c_^*^ term just prior to (β + 1); that is, the exponent in the second term the denominator should read: 0.4(M_c_ - M_c_^*^)(β + 1). The authors wish to draw these errors to the attention of any readers who will be using the expression and equation.

  17. Three-point Correlation Functions of SDSS Galaxies: Luminosity and Color Dependence in Redshift and Projected Space

    NASA Astrophysics Data System (ADS)

    McBride, Cameron K.; Connolly, Andrew J.; Gardner, Jeffrey P.; Scranton, Ryan; Newman, Jeffrey A.; Scoccimarro, Román; Zehavi, Idit; Schneider, Donald P.

    2011-01-01

    The three-point correlation function (3PCF) provides an important view into the clustering of galaxies that is not available to its lower order cousin, the two-point correlation function (2PCF). Higher order statistics, such as the 3PCF, are necessary to probe the non-Gaussian structure and shape information expected in these distributions. We measure the clustering of spectroscopic galaxies in the Main Galaxy Sample of the Sloan Digital Sky Survey, focusing on the shape or configuration dependence of the reduced 3PCF in both redshift and projected space. This work constitutes the largest number of galaxies ever used to investigate the reduced 3PCF, using over 220,000 galaxies in three volume-limited samples. We find significant configuration dependence of the reduced 3PCF at 3-27 h -1 Mpc, in agreement with ΛCDM predictions and in disagreement with the hierarchical ansatz. Below 6 h -1 Mpc, the redshift space reduced 3PCF shows a smaller amplitude and weak configuration dependence in comparison with projected measurements suggesting that redshift distortions, and not galaxy bias, can make the reduced 3PCF appear consistent with the hierarchical ansatz. The reduced 3PCF shows a weaker dependence on luminosity than the 2PCF, with no significant dependence on scales above 9 h -1 Mpc. On scales less than 9 h -1 Mpc, the reduced 3PCF appears more affected by galaxy color than luminosity. We demonstrate the extreme sensitivity of the 3PCF to systematic effects such as sky completeness and binning scheme, along with the difficulty of resolving the errors. Some comparable analyses make assumptions that do not consistently account for these effects.

  18. Modelling the cosmological co-evolution of supermassive black holes and galaxies - I. BH scaling relations and the AGN luminosity function

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    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 by Croton et al. and De Lucia and Blaizot, 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 observed mass dropout rate in cooling flows; (ii) the exponential cut-off in the bright end of the galaxy luminosity function and (iii) the bulge-dominated morphologies and old stellar ages of the most massive galaxies in clusters. This paper is the first of a series in which we investigate how well this model can also reproduce the physical properties of BHs and AGN. Here we analyse the scaling relations, the fundamental plane and the mass function of BHs, and compare them with the most recent observational data. Moreover, we extend the semi-analytic model to follow the evolution of the BH mass accretion and its conversion into radiation, and compare the derived AGN bolometric luminosity function with the observed one. While we find for the most part a very good agreement between predicted and observed BH properties, the semi-analytic model underestimates the number density of luminous AGN at high redshifts, independently of the adopted Eddington factor and accretion efficiency. However, an agreement with the observations is possible within the framework of our model, provided it is assumed that the cold gas fraction accreted by BHs at high redshifts is larger than at low redshifts.

  19. The Luminosity Function of Star Clusters in 20 Star-forming Galaxies Based on Hubble Legacy Archive Photometry

    NASA Astrophysics Data System (ADS)

    Whitmore, Bradley C.; Chandar, Rupali; Bowers, Ariel S.; Larsen, Soeren; Lindsay, Kevin; Ansari, Asna; Evans, Jessica

    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/dLvpropL 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 clusters

  20. The Bright End of the z ˜ 9 and z ˜ 10 UV Luminosity Functions Using All Five CANDELS Fields*

    NASA Astrophysics Data System (ADS)

    Bouwens, R. J.; Oesch, P. A.; Labbé, I.; Illingworth, G. D.; Fazio, G. G.; Coe, D.; Holwerda, B.; Smit, R.; Stefanon, M.; van Dokkum, P. G.; Trenti, M.; Ashby, M. L. N.; Huang, J.-S.; Spitler, L.; Straatman, C.; Bradley, L.; Magee, D.

    2016-10-01

    The deep, wide-area (˜800-900 arcmin2) near-infrared/WFC3/IR + Spitzer/IRAC observations over the CANDELS fields have been a remarkable resource for constraining the bright end of high-redshift UV luminosity functions. However, the lack of Hubble Space Telescope (HST) 1.05 μm observations over the CANDELS fields has made it difficult to identify z ˜ 9-10 sources robustly, since such data are needed to confirm the presence of an abrupt Lyman break at 1.2 μm. Here, we report on the successful identification of many such z ˜ 9-10 sources from a new HST program (z9-CANDELS) that targets the highest-probability z ˜ 9-10 galaxy candidates with observations at 1.05 μm, to search for a robust Lyman-break at 1.2 μm. The potential z ˜ 9-10 candidates were preselected from the full HST, Spitzer/IRAC S-CANDELS observations, and the deepest-available ground-based optical+near-infrared observations (CFHTLS-DEEP+HUGS+UltraVISTA+ZFOURGE). We identified 15 credible z ˜ 9-10 galaxies over the CANDELS fields. Nine of these galaxies lie at z ˜ 9 and five are new identifications. Our targeted follow-up strategy has proven to be very efficient in making use of scarce HST time to secure a reliable sample of z ˜ 9-10 galaxies. Through extensive simulations, we replicate the selection process for our sample (both the preselection and follow-up) and use it to improve current estimates for the volume density of bright z ˜ 9 and z ˜ 10 galaxies. The volume densities we find are 5{}-2+3× and {8}-3+9× lower, respectively, than those found at z ˜ 8. When compared with the best-fit evolution (i.e., d {{log}}10 {ρ }{UV}/{dz}=-0.29+/- 0.02) in the UV luminosity densities from z ˜ 8 to z ˜ 4 integrated to 0.3{L}z=3* (-20 mag), these luminosity densities are {2.6}-0.9+1.5× and {2.2}-1.1+2.0× lower, respectively, than the extrapolated trends. Our new results are broadly consistent with the “accelerated evolution” scenario at z > 8, consistent with that seen in many models

  1. Population studies in groups and clusters of galaxies. IV - Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    NASA Technical Reports Server (NTRS)

    Ferguson, Henry C.; Sandage, Allan

    1991-01-01

    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.

  2. Population studies in groups and clusters of galaxies. IV. Comparison of the luminosity functions and morphological-type distributions in seven nearby groups

    SciTech Connect

    Ferguson, H.C.; Sandage, A. Observatories of the Carnegie Institution, Pasadena, CA Space Telescope Science Institute, Baltimore, MD )

    1991-03-01

    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.

  3. THE UDF05 FOLLOW-UP OF THE HUBBLE ULTRA DEEP FIELD. III. THE LUMINOSITY FUNCTION AT z {approx} 6

    SciTech Connect

    Su Jian; Stiavelli, Massimo; Bergeron, Eddie; Bradley, Larry; Dahlen, Tomas; Ferguson, Henry C.; Koekemoer, Anton; Lucas, Ray A.; Panagia, Nino; Pavlovsky, Cheryl; Oesch, Pascal; Carollo, Marcella; Lilly, Simon; Trenti, Michele; Giavalisco, Mauro; Mobasher, Bahram

    2011-09-10

    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 {approx} 6 LF are {alpha} = 1.87 {+-} 0.14, M{sub *} = -20.25 {+-} 0.23, and {phi}{sub *} = 1.77{sup +0.62}{sub -0.49} x 10{sup -3} Mpc{sup -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 {approx} 6 to reach an agreement in the 95% confidence level that -20.45 < M{sub *} < -20.05 and -1.90 < {alpha} < -1.55. The luminosity density has been found not to evolve significantly between z {approx} 6 and z {approx} 5, but considerable evolution is detected from z {approx} 6 to z {approx} 3.

  4. THE TAIWAN ECDFS NEAR-INFRARED SURVEY: VERY BRIGHT END OF THE LUMINOSITY FUNCTION AT z > 7

    SciTech Connect

    Hsieh, Bau-Ching; Wang, Wei-Hao; Lin, Lihwai; Lim, Jeremy; Ho, Paul T. P.; Yan, Haojing; Karoji, Hiroshi; Tsai, Chao-Wei

    2012-04-10

    The primary goal of the Taiwan ECDFS Near-Infrared Survey (TENIS) is to find well-screened galaxy candidates at z > 7 (z' dropout) in the Extended Chandra Deep Field-South (ECDFS). To this end, TENIS provides relatively deep J and K{sub s} data ({approx}25.3 ABmag, 5{sigma}) for an area of 0.5 Multiplication-Sign 0.5 deg. Leveraged with existing data at mid-infrared to optical wavelengths, this allows us to screen for the most luminous high-z objects, which are rare and thus require a survey over a large field to be found. We introduce new color selection criteria to select a z > 7 sample with minimal contaminations from low-z galaxies and Galactic cool stars; to reduce confusion in the relatively low angular resolution Infrared Array Camera (IRAC) images, we introduce a novel deconvolution method to measure the IRAC fluxes of individual sources. Illustrating perhaps the effectiveness at which we screen out interlopers, we find only one z > 7 candidate, TENIS-ZD1. The candidate has a weighted z{sub phot} of 7.8, and its colors and luminosity indicate a young (45M years old) starburst galaxy with a stellar mass of 3.2 Multiplication-Sign 10{sup 10} M{sub Sun }. The result matches with the observational luminosity function analysis and the semianalytic simulation result based on the Millennium Simulations, which may over predict the volume density for high-z massive galaxies. The existence of TENIS-ZD1, if confirmed spectroscopically to be at z > 7, therefore poses a challenge to current theoretical models for how so much mass can accumulate in a galaxy at such a high redshift.

  5. The Taiwan ECDFS Near-Infrared Survey: Very Bright End of the Luminosity Function at z > 7

    NASA Astrophysics Data System (ADS)

    Hsieh, Bau-Ching; Wang, Wei-Hao; Yan, Haojing; Lin, Lihwai; Karoji, Hiroshi; Lim, Jeremy; Ho, Paul T. P.; Tsai, Chao-Wei

    2012-04-01

    The primary goal of the Taiwan ECDFS Near-Infrared Survey (TENIS) is to find well-screened galaxy candidates at z > 7 (z' dropout) in the Extended Chandra Deep Field-South (ECDFS). To this end, TENIS provides relatively deep J and Ks data (~25.3 ABmag, 5σ) for an area of 0.5 × 0.5 deg. Leveraged with existing data at mid-infrared to optical wavelengths, this allows us to screen for the most luminous high-z objects, which are rare and thus require a survey over a large field to be found. We introduce new color selection criteria to select a z > 7 sample with minimal contaminations from low-z galaxies and Galactic cool stars; to reduce confusion in the relatively low angular resolution Infrared Array Camera (IRAC) images, we introduce a novel deconvolution method to measure the IRAC fluxes of individual sources. Illustrating perhaps the effectiveness at which we screen out interlopers, we find only one z > 7 candidate, TENIS-ZD1. The candidate has a weighted z phot of 7.8, and its colors and luminosity indicate a young (45M years old) starburst galaxy with a stellar mass of 3.2 × 1010 M ⊙. The result matches with the observational luminosity function analysis and the semianalytic simulation result based on the Millennium Simulations, which may over predict the volume density for high-z massive galaxies. The existence of TENIS-ZD1, if confirmed spectroscopically to be at z > 7, therefore poses a challenge to current theoretical models for how so much mass can accumulate in a galaxy at such a high redshift.

  6. The Mass-loss Return from Evolved Stars to the Large Magellanic Cloud. VI. Luminosities and Mass-loss Rates on Population Scales

    NASA Astrophysics Data System (ADS)

    Riebel, D.; Srinivasan, S.; Sargent, B.; Meixner, M.

    2012-07-01

    We present results from the first application of the Grid of Red Supergiant and Asymptotic Giant Branch ModelS (GRAMS) model grid to the entire evolved stellar population of the Large Magellanic Cloud (LMC). GRAMS is a pre-computed grid of 80,843 radiative transfer models of evolved stars and circumstellar dust shells composed of either silicate or carbonaceous dust. We fit GRAMS models to ~30,000 asymptotic giant branch (AGB) and red supergiant (RSG) stars in the LMC, using 12 bands of photometry from the optical to the mid-infrared. Our published data set consists of thousands of evolved stars with individually determined evolutionary parameters such as luminosity and mass-loss rate. The GRAMS grid has a greater than 80% accuracy rate discriminating between oxygen- and carbon-rich chemistry. The global dust injection rate to the interstellar medium (ISM) of the LMC from RSGs and AGB stars is on the order of 2.1 × 10-5 M ⊙ yr-1, equivalent to a total mass injection rate (including the gas) into the ISM of ~6 × 10-3 M ⊙ yr-1. Carbon stars inject two and a half times as much dust into the ISM as do O-rich AGB stars, but the same amount of mass. We determine a bolometric correction factor for C-rich AGB stars in the K s band as a function of J - K s color, BC_{K_{s}} = -0.40(J-K_{s})^2 + 1.83(J-K_{s}) + 1.29. We determine several IR color proxies for the dust mass-loss rate (\\dot{M}_{d}) from C-rich AGB stars, such as log \\dot{M_{d}} = ({-18.90}/({(K_{s}-[8.0])+3.37}))-5.93. We find that a larger fraction of AGB stars exhibiting the "long-secondary period" phenomenon are more O-rich than stars dominated by radial pulsations, and AGB stars without detectable mass loss do not appear on either the first-overtone or fundamental-mode pulsation sequences.

  7. The luminosity function at the end of the main sequence: Results of a deep, large-area, CCD survey for cool dwarfs

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, J. Davy; Mcgraw, John T.; Hess, Thomas R.; Liebert, James; Mccarthy, Donald W., Jr.

    1994-01-01

    The luminosity function at the end of the main sequence is determined from V, R, and I data taken by the charge coupled devices (CCD)/Transit Instrument, a dedicated telescope surveying an 8.25 min wide strip of sky centered at delta = +28 deg, thus sampling Galactic latitudes of +90 deg down to -35 deg. A selection of 133 objects chosen via R - I and V - I colors has been observed spectroscopically at the 4.5 m Multiple Mirror Telescope to assess contributions by giants and subdwarfs and to verify that the reddest targets are objects of extremely late spectral class. Eighteen dwarfs of type M6 or later have been discovered, with the latest being of type M8.5. Data used for the determination of the luminosity function cover 27.3 sq. deg down to a completeness limit of R = 19.0. This luminosity function, computed at V, I, and bolometric magnitudes, shows an increase at the lowest luminosities, corresponding to spectral types later than M6- an effect suggested in earlier work by Reid & Gilmore and Legget & Hawkins. When the luminosity function is segregated into north Galactic and south Galactic portions, it is found that the upturn at faint magnitudes exists only in the southern sample. In fact, no dwarfs with M(sub I) is greater than or equal to 12.0 are found within the limiting volume of the 19.4 sq deg northern sample, in stark contrast to the smaller 7.9 sq deg area at southerly latitudes where seven such dwarfs are found. This fact, combined with the fact that the Sun is located approximately 10-40 pc north of the midplane, suggests that the latest dwarfs are part of a young population with a scale height much smaller than the 350 pc value generally adopted for other M dwarfs. These objects comprise a young population either because the lower metallicities prevelant at earlier epochs inhibited the formation of late M dwarfs or because the older counterparts of this population have cooled beyond current detection limits. The latter scenario would hold if these

  8. THE MID-INFRARED LUMINOSITY FUNCTION AT z < 0.3 FROM 5MUSES: UNDERSTANDING THE STAR FORMATION/ACTIVE GALACTIC NUCLEUS BALANCE FROM A SPECTROSCOPIC VIEW

    SciTech Connect

    Wu Yanling; Shi Yong; Helou, George; Armus, Lee; Stierwalt, Sabrina; Dale, Daniel A.; Papovich, Casey; Rahman, Nurur; Dasyra, Kalliopi E-mail: yong@ipac.caltech.edu E-mail: lee@ipac.caltech.edu E-mail: ddale@uwyo.edu E-mail: nurur@astro.umd.edu

    2011-06-10

    We present rest-frame 15 and 24 {mu}m luminosity functions (LFs) and the corresponding star-forming LFs at z < 0.3 derived from the 5MUSES sample. Spectroscopic redshifts have been obtained for {approx}98% of the objects and the median redshift is {approx}0.12. The 5-35 {mu}m Infrared Spectrograph spectra allow us to estimate accurately the luminosities and build the LFs. Using a combination of starburst and quasar templates, we quantify the star formation (SF) and active galactic nucleus (AGN) contributions in the mid-IR spectral energy distribution. We then compute the SF LFs at 15 and 24 {mu}m, and compare with the total 15 and 24 {mu}m LFs. When we remove the contribution of AGNs, the bright end of the LF exhibits a strong decline, consistent with the exponential cutoff of a Schechter function. Integrating the differential LF, we find that the fractional contribution by SF to the energy density is 58% at 15 {mu}m and 78% at 24 {mu}m, while it goes up to {approx}86% when we extrapolate our mid-IR results to the total IR luminosity density. We confirm that the AGNs play more important roles energetically at high luminosities. Finally, we compare our results with work at z {approx} 0.7 and confirm that evolution on both luminosity and density is required to explain the difference in the LFs at different redshifts.

  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

    NASA Astrophysics Data System (ADS)

    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.

  10. 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

    SciTech Connect

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

    2014-05-10

    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.

  11. Chandra ACIS Survey of X-Ray Point Sources in Nearby Galaxies. II. X-Ray Luminosity Functions and Ultraluminous X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Wang, Song; Qiu, Yanli; Liu, Jifeng; Bregman, Joel N.

    2016-09-01

    Based on the recently completed Chandra/ACIS survey of X-ray point sources in nearby galaxies, we study the X-ray luminosity functions (XLFs) for X-ray point sources in different types of galaxies and the statistical properties of ultraluminous X-ray sources (ULXs). Uniform procedures are developed to compute the detection threshold, to estimate the foreground/background contamination, and to calculate the XLFs for individual galaxies and groups of galaxies, resulting in an XLF library of 343 galaxies of different types. With the large number of surveyed galaxies, we have studied the XLFs and ULX properties across different host galaxy types, and confirm with good statistics that the XLF slope flattens from lenticular (α ˜ 1.50 ± 0.07) to elliptical (˜1.21 ± 0.02), to spirals (˜0.80 ± 0.02), to peculiars (˜0.55 ± 0.30), and to irregulars (˜0.26 ± 0.10). The XLF break dividing the neutron star and black hole binaries is also confirmed, albeit at quite different break luminosities for different types of galaxies. A radial dependency is found for ellipticals, with a flatter XLF slope for sources located between D 25 and 2D 25, suggesting the XLF slopes in the outer region of early-type galaxies are dominated by low-mass X-ray binaries in globular clusters. This study shows that the ULX rate in early-type galaxies is 0.24 ± 0.05 ULXs per surveyed galaxy, on a 5σ confidence level. The XLF for ULXs in late-type galaxies extends smoothly until it drops abruptly around 4 × 1040 erg s-1, and this break may suggest a mild boundary between the stellar black hole population possibly including 30 M ⊙ black holes with super-Eddington radiation and intermediate mass black holes.

  12. A study of the discrepant QSO X-ray luminosity function from the HEAO-2 data archive

    NASA Technical Reports Server (NTRS)

    Margon, B.

    1984-01-01

    An in-progress investigation aimed at characterizing the X-ray luminosity of very faint QSOs is described. More than 100 faint, previously uncataloged QSOs which lie in areas imaged in X rays at very high sensitivity were discovered.

  13. PROBING VERY BRIGHT END OF GALAXY LUMINOSITY FUNCTION AT z {approx}> 7 USING HUBBLE SPACE TELESCOPE PURE PARALLEL OBSERVATIONS

    SciTech Connect

    Yan Haojing; Yan Lin; Zamojski, Michel A.; Windhorst, Rogier A.; McCarthy, Patrick J.; Fan Xiaohui; Dave, Romeel; Roettgering, Huub J. A.; Koekemoer, Anton M.; Robertson, Brant E.; Cai Zheng

    2011-02-10

    We report the first results from the Hubble Infrared Pure Parallel Imaging Extragalactic Survey, which utilizes the pure parallel orbits of the Hubble Space Telescope to do deep imaging along a large number of random sightlines. To date, our analysis includes 26 widely separated fields observed by the Wide Field Camera 3, which amounts to 122.8 arcmin{sup 2} in total area. We have found three bright Y{sub 098}-dropouts, which are candidate galaxies at z {approx}> 7.4. One of these objects shows an indication of peculiar variability and its nature is uncertain. The other two objects are among the brightest candidate galaxies at these redshifts known to date (L>2L*). Such very luminous objects could be the progenitors of the high-mass Lyman break galaxies observed at lower redshifts (up to z {approx} 5). While our sample is still limited in size, it is much less subject to the uncertainty caused by 'cosmic variance' than other samples because it is derived using fields along many random sightlines. We find that the existence of the brightest candidate at z {approx} 7.4 is not well explained by the current luminosity function (LF) estimates at z {approx} 8. However, its inferred surface density could be explained by the prediction from the LFs at z {approx} 7 if it belongs to the high-redshift tail of the galaxy population at z {approx} 7.

  14. LOW-MASS SUPPRESSION OF THE SATELLITE LUMINOSITY FUNCTION DUE TO THE SUPERSONIC BARYON-COLD-DARK-MATTER RELATIVE VELOCITY

    SciTech Connect

    Bovy, Jo; Dvorkin, Cora

    2013-05-01

    We study the effect of the supersonic baryon-cold-dark-matter (CDM) flow, which has recently been shown to have a large effect on structure formation during the dark ages 10 {approx}< z {approx}< 1000, on the abundance of luminous, low-mass satellite galaxies around galaxies like the Milky Way. As the supersonic baryon-CDM flow significantly suppresses both the number of halos formed and the amount of baryons accreted onto such halos of masses 10{sup 6} < M{sub halo}/M{sub Sun} < 10{sup 8} at z {approx}> 10, a large effect results on the stellar luminosity function before reionization. As halos of these masses are believed to have very little star formation after reionization due to the effects of photoheating by the ultraviolet background, this effect persists to the present day. We calculate that the number of low-mass 10{sup 6} < M{sub halo}/M{sub Sun} < 5 Multiplication-Sign 10{sup 7} halos that host luminous satellite galaxies today is typically suppressed by 50%, with values ranging up to 90% in regions where the initial supersonic velocity is high. We show that this previously ignored cosmological effect resolves some of the tension between the observed and predicted number of low-mass satellites in the Milky Way, reducing the need for other mass-dependent star-formation suppression before reionization.

  15. Galaxies in Filaments have More Satellites: The Influence of the Cosmic Web on the Satellite Luminosity Function in the SDSS

    NASA Astrophysics Data System (ADS)

    Guo, Quan; Tempel, E.; Libeskind, N. I.

    2015-02-01

    We investigate whether the satellite luminosity function (LF) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample, and potential satellites (that are up to four magnitudes fainter than their hosts) 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 satellite LF of both the filament and nonfilament samples and find that, on average, the satellite LF of galaxies in filaments is significantly higher than those of galaxies not in filaments. The filamentary environment can increase the abundance of the brightest satellites (M sat. < M prim. + 2.0) by a factor of ~2 compared with nonfilament isolated galaxies. This result is independent of the primary galaxy magnitude, although the satellite LF of galaxies in the faintest magnitude bin is too noisy to determine if such a dependence exists. Because our filaments are extracted from a spectroscopic flux-limited sample, we consider the possibility that the difference in satellite LF is due to a redshift, color, or environmental bias, finding these to be insufficient to explain our result. The dependence of the satellite LF on the cosmic web suggests that the filamentary environment may have a strong effect on the efficiency of galaxy formation.

  16. Common envelope mechanisms: constraints from the X-ray luminosity function of high-mass X-ray binaries

    SciTech Connect

    Zuo, Zhao-Yu; Li, Xiang-Dong E-mail: lixd@nju.edu.cn

    2014-12-10

    We use the measured X-ray luminosity function (XLF) of high-mass X-ray binaries (HMXBs) in nearby star-forming galaxies to constrain the common envelope (CE) mechanisms, which play a key role in governing the binary evolution. We find that the XLF can be reproduced quite closely under both CE mechanisms usually adopted, i.e., the α{sub CE} formalism and the γ algorithm, with a reasonable range of parameters considered. Provided that the parameter combination is the same, the γ algorithm is likely to produce more HMXBs than the α{sub CE} formalism, by a factor of up to ∼10. In the framework of the α{sub CE} formalism, a high value of α{sub CE} is required to fit the observed XLF, though it does not significantly affect the global number of the HMXB populations. We present the detailed components of the HMXB populations under the γ algorithm 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.

  17. RECONSTRUCTING THE NEAR-INFRARED BACKGROUND FLUCTUATIONS FROM KNOWN GALAXY POPULATIONS USING MULTIBAND MEASUREMENTS OF LUMINOSITY FUNCTIONS

    SciTech Connect

    Helgason, Kari; Ricotti, Massimo; Kashlinsky, Alexander

    2012-06-20

    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 {approx} 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.

  18. GALAXIES IN FILAMENTS HAVE MORE SATELLITES: THE INFLUENCE OF THE COSMIC WEB ON THE SATELLITE LUMINOSITY FUNCTION IN THE SDSS

    SciTech Connect

    Guo, Quan; Libeskind, N. I.; Tempel, E.

    2015-02-20

    We investigate whether the satellite luminosity function (LF) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample, and potential satellites (that are up to four magnitudes fainter than their hosts) 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 satellite LF of both the filament and nonfilament samples and find that, on average, the satellite LF of galaxies in filaments is significantly higher than those of galaxies not in filaments. The filamentary environment can increase the abundance of the brightest satellites (M {sub sat.} < M {sub prim.} + 2.0) by a factor of ∼2 compared with nonfilament isolated galaxies. This result is independent of the primary galaxy magnitude, although the satellite LF of galaxies in the faintest magnitude bin is too noisy to determine if such a dependence exists. Because our filaments are extracted from a spectroscopic flux-limited sample, we consider the possibility that the difference in satellite LF is due to a redshift, color, or environmental bias, finding these to be insufficient to explain our result. The dependence of the satellite LF on the cosmic web suggests that the filamentary environment may have a strong effect on the efficiency of galaxy formation.

  19. C-M diagram and luminosity function of the Galactic globular cluster NGC 7099. I. Photographic photometry

    SciTech Connect

    Piotto, G.; Rosino, L.; Capaccioli, M.; Ortolani, S.; Alcaino, G.

    1987-08-01

    New photographic photometry of about 4400 stars in the field of the Galactic globular cluster NGC 7099 = M30 is presented. A C-M diagram and a luminosity function are obtained from this photometry. The distance modulus is estimated at 14.5 + or - 0.5 assuming V(HB) = 15.11 + or - 0.10 and E(B-V) = 0.03 + or - 0.03. The metallicity is (Fe/H) = 1.9 + or - 0.3 based on the dereddened color index (B-V)0,g = 0.71 + or - 0.03. The theoretical isochrones of VandenBerg and Bell (1985) give a better fit to the observations assuming (Fe/H) = -1.8, (m-M)V = 14.6, and E(B-V) = 0.02. A fair fit is also obtained using isochrones of low iron content with an oxygen enhancement of 0.7. From the fit, an age of 17 + or - 4 Gyr is deduced. 41 references.

  20. Clustering, cosmology and a new era of black hole demographics- II. The conditional luminosity functions of Type 2 and Type 1 active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ballantyne, D. R.

    2017-01-01

    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 then 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 ≈ 0 and 0.9. At both z, there is no statistically significant difference in the mean halo mass of Type 2 and 1 AGNs at any luminosity. There is marginal evidence that Type 1 AGNs may have larger halo masses than Type 2s, which would be consistent with an evolutionary picture where quasars are initially obscured and then subsequently reveal themselves as Type 1s. As the Type 1 lifetime is longer, the host halo will increase somewhat in mass during the Type 1 phase. The CLF technique will be a powerful way to study the properties of many AGNs subsets (e.g. radio-loud, Compton-thick) as future wide-area X-ray and optical surveys substantially increase our ability to place AGNs in their cosmological context.

  1. The z ˜ 6 Luminosity Function Fainter than -15 mag from the Hubble Frontier Fields: The Impact of Magnification Uncertainties

    NASA Astrophysics Data System (ADS)

    Bouwens, R. J.; Oesch, P. A.; Illingworth, G. D.; Ellis, R. S.; Stefanon, M.

    2017-07-01

    We use the largest sample of z˜ 6 galaxies to date from the first four Hubble Frontier Fields clusters to set constraints on the shape of the z˜ 6 luminosity functions (LFs) to fainter than {M}{UV,{AB}}=-14 mag. We quantify, for the first time, the impact of magnification uncertainties on LF results and thus provide more realistic constraints than other recent work. Our simulations reveal that, for the highly magnified sources, the systematic uncertainties can become extremely large fainter than -14 mag, reaching several orders of magnitude at 95% confidence at approximately -12 mag. Our new forward-modeling formalism incorporates the impact of magnification uncertainties into the LF results by exploiting the availability of many independent magnification models for the same cluster. One public magnification model is used to construct a mock high-redshift galaxy sample that is then analyzed using the other magnification models to construct an LF. Large systematic errors occur at high magnifications (μ ≳ 30) because of differences between the models. The volume densities we derive for faint (≳-17 mag) sources are ˜3-4× lower than one recent report and give a faint-end slope α =-1.92+/- 0.04, which is 3.0-3.5σ shallower (including or not including the size uncertainties, respectively). We introduce a new curvature parameter δ to model the faint end of the LF and demonstrate that the observations permit (at 68% confidence) a turn-over at z˜ 6 in the range of -15.3 to -14.2 mag, depending on the assumed lensing model. The present consideration of magnification errors and new size determinations raise doubts about previous reports regarding the form of the LF at > -14 {mag}. We discuss the implications of our turn-over constraints in the context of recent theoretical predictions.

  2. The UV Luminosity Function of z˜ 7 galaxies from wide and deep HST and ESO/VLT surveys

    NASA Astrophysics Data System (ADS)

    Grazian, A.; Pentericci, L.; Castellano, M.; Fontana, A.

    The study of the Luminosity Function (LF) of Lyman Break Galaxies (LBGs) at z=7 is very important for ascertaining their role in the reionization of the Universe. In this work we plan to perform a robust determination of the UV LF for LBGs at z˜ 7. To this aim, we have assembled a large sample of candidate LBGs at z˜ 7 from different surveys, spanning a large variety of areas and depths. In particular, we have combined data from the deep (J<27.4) and ultradeep (J<29.2) surveys recently acquired with the new WFC3 NIR camera on HST, over the GOODS-ERS (˜40 sq. arcmin.) and the HUDF (˜4 sq. arcmin.) fields, with a ground based survey in wide and relatively shallow areas (˜200 sq. arcmin.) from Hawk-I@VLT. We have used public images in the z band to select z-dropout galaxies, and other public data both in the blue (UBVRI) and in the red bands to reject possible low-redshift interlopers. We have found that the number density of faint LBGs at z˜ 7 is strongly dependent on the assumption made on the half light distributions of the simulated galaxies, used to correct the observed sample for incompleteness. We conclude that galaxies at z˜ 7 are unable to reionize the Universe unless there is a significant evolution in the clumpiness of the inter-galactic medium (IGM) or in the escape fraction of ionising photons or, alternatively, there is a large population of z˜ 7 LBGs with large physical dimensions but still not detected by the present observations.

  3. A molecular line scan in the Hubble deep field north: Constraints on the co luminosity function and the cosmic H{sub 2} density

    SciTech Connect

    Walter, F.; Decarli, R.; Da Cunha, E.; Sargent, M.; Dickinson, M.; Daddi, E.; Riechers, D.; Ellis, R.; Stark, D.; Weiner, B.; Aravena, M.; Bell, E.; Bertoldi, F.; Cox, P.; Downes, D.; Neri, R.; Lentati, L.; Maiolino, R.; Menten, K. M.; 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.

  4. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-line Region

    NASA Astrophysics Data System (ADS)

    Du, Pu; Lu, Kai-Xing; Zhang, Zhi-Xiang; Huang, Ying-Ke; Wang, Kai; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Fan, Xu-Liang; Fang, Xiang-Er; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Ho, Luis C.; Wang, Jian-Min; SEAMBH Collaboration

    2016-07-01

    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014 and 2015. Ten new targets were selected from the quasar sample of the Sloan Digital Sky Survey (SDSS), which have generally been more luminous than the SEAMBH candidates in the last two years. Hβ lags ({τ }{{H}β }) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known R H β-L 5100 relation. The five quasars have dimensionless accretion rates of \\dot{{M}\\quad }=10-103. Combining these with measurements of the previous SEAMBHs, we find that the reduction of Hβ lags depends tightly on accretion rates, {τ }{{H}β }/{τ }R-L\\propto {\\dot{{M}}}-0.42, where {τ }R-L is the Hβ lag from the normal R H β-L 5100 relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: {R}{{H}β }={α }1{{\\ell }}44{β 1} {min} [1,{(\\dot{{M}}/{\\dot{{M}}}c)}-{γ 1}], where {{\\ell }}44={L}5100/{10}44 {erg} {{{s}}}-1 is the 5100 Å continuum luminosity, and the coefficients are {α }1={29.6}-2.8+2.7 lt-day, {β }1={0.56}-0.03+0.03, {γ }1={0.52}-0.16+0.33, and {\\dot{{M}}}c={11.19}-6.22+2.29. This relation is applicable to AGNs over a wide range of accretion rates, from 10-3 to 103. Implications of this new relation are briefly discussed.

  5. THE BRIGHTEST OF REIONIZING GALAXIES SURVEY: CONSTRAINTS ON THE BRIGHT END OF THE z {approx} 8 LUMINOSITY FUNCTION

    SciTech Connect

    Bradley, L. D.; Stiavelli, M.; Pirzkal, N.; Trenti, M.; Oesch, P. A.; Bouwens, R. J.; Shull, J. M.; Holwerda, B. W.

    2012-12-01

    We report the discovery of 33 Lyman-break galaxy candidates at z {approx} 8 detected in Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging as part of the Brightest of Reionizing Galaxies (BoRG) pure-parallel survey. The ongoing BoRG survey currently has the largest area (274 arcmin{sup 2}) with Y {sub 098} (or Y {sub 105}), J {sub 125}, and H {sub 160} band coverage needed to search for z {approx} 8 galaxies, about three times the current CANDELS area, and slightly larger than what will be the final CANDELS wide component with Y {sub 105} data (required to select z {approx} 8 sources). Our sample of 33 relatively bright Y {sub 098}-dropout galaxies have J {sub 125}-band magnitudes between 25.5 and 27.4 mag. This is the largest sample of bright (J {sub 125} {approx}< 27.4) z {approx} 8 galaxy candidates presented to date. Combining our data set with the Hubble Ultra-Deep Field data set, we constrain the rest-frame ultraviolet galaxy luminosity function at z {approx} 8 over the widest dynamic range currently available. The combined data sets are well fitted by a Schechter function, i.e., {phi} (L) = {phi}{sub *} (L/L{sub *}){sup {alpha}} e{sup -(}L{sup /L{sub *})}, without evidence for an excess of sources at the bright end. At 68% confidence, for h = 0.7 we derive {phi}{sub *} = (4.3{sup +3.5} {sub -2.1}) Multiplication-Sign 10{sup -4} Mpc{sup -3}, M {sub *} = -20.26{sup +0.29} {sub -0.34}, and a very steep faint-end slope {alpha} = -1.98{sup +0.23} {sub -0.22}. While the best-fit parameters still have a strong degeneracy, especially between {phi}{sub *} and M {sub *}, our improved coverage at the bright end has reduced the uncertainty of the faint-end power-law slope at z {approx} 8 compared to the best previous determination at {+-}0.4. With a future expansion of the BoRG survey, combined with planned ultradeep WFC3/IR observations, it will be possible to further reduce this uncertainty and clearly demonstrate the steepening of the faint-end slope compared

  6. Some Like it Hot: Linking Diffuse X-Ray Luminosity, Baryonic Mass, and Star Formation Rate in Compact Groups of Galaxies

    NASA Technical Reports Server (NTRS)

    Desjardins, Tyler D.; Gallagher, Sarah C.; Hornschemeier, Ann E.; Mulchaey, John S.; Walker, Lisa May; Brandt, Willian N.; Charlton, Jane C.; Johnson, Kelsey E.; Tzanavaris, Panayiotis

    2014-01-01

    We present an analysis of the diffuse X-ray emission in 19 compact groups (CGs) of galaxies observed with Chandra. The hottest, most X-ray luminous CGs agree well with the galaxy cluster X-ray scaling relations in L(x-T) and (L(x-sigma), even in CGs where the hot gas is associated with only the brightest galaxy. Using Spitzer photometry, we compute stellar masses and classify Hickson CGs 19, 22, 40, and 42, and RSCGs 32, 44, and 86 as fossil groups using a new definition for fossil systems that includes a broader range of masses. We find that CGs with total stellar and Hi masses are great than or equal to 10(sup (11.3) solar mass are often X-ray luminous, while lower-mass CGs only sometimes exhibit faint, localized X-ray emission. Additionally, we compare the diffuse X-ray luminosity against both the total UV and 24 micron star formation rates of each CG and optical colors of the most massive galaxy in each of the CGs. The most X-ray luminous CGs have the lowest star formation rates, likely because there is no cold gas available for star formation, either because the majority of the baryons in these CGs are in stars or the X-ray halo, or due togas stripping from the galaxies in CGs with hot halos. Finally, the optical colors that trace recent star formation histories of the most massive group galaxies do not correlate with the X-ray luminosities of the CGs, indicating that perhaps the current state of the X-ray halos is independent of the recent history of stellar mass assembly in the most massive galaxies.

  7. Some like it hot: Linking diffuse X-ray luminosity, baryonic mass, and star formation rate in compact groups of galaxies

    SciTech Connect

    Desjardins, Tyler D.; Gallagher, Sarah C.; Hornschemeier, Ann E.; Tzanavaris, Panayiotis; Walker, Lisa May; Johnson, Kelsey E.; Brandt, William N.; Charlton, Jane C.

    2014-08-01

    We present an analysis of the diffuse X-ray emission in 19 compact groups (CGs) of galaxies observed with Chandra. The hottest, most X-ray luminous CGs agree well with the galaxy cluster X-ray scaling relations in L{sub X} -T and L{sub X} -σ, even in CGs where the hot gas is associated with only the brightest galaxy. Using Spitzer photometry, we compute stellar masses and classify Hickson CGs 19, 22, 40, and 42, and RSCGs 32, 44, and 86 as fossil groups using a new definition for fossil systems that includes a broader range of masses. We find that CGs with total stellar and H I masses ≳ 10{sup 11.3} M{sub ☉} are often X-ray luminous, while lower-mass CGs only sometimes exhibit faint, localized X-ray emission. Additionally, we compare the diffuse X-ray luminosity against both the total UV and 24 μm star formation rates of each CG and optical colors of the most massive galaxy in each of the CGs. The most X-ray luminous CGs have the lowest star formation rates, likely because there is no cold gas available for star formation, either because the majority of the baryons in these CGs are in stars or the X-ray halo, or due to gas stripping from the galaxies in CGs with hot halos. Finally, the optical colors that trace recent star formation histories of the most massive group galaxies do not correlate with the X-ray luminosities of the CGs, indicating that perhaps the current state of the X-ray halos is independent of the recent history of stellar mass assembly in the most massive galaxies.

  8. The Effect of Variability on X-Ray Binary Luminosity Functions: Multiple-epoch Observations of NGC 300 with Chandra

    NASA Astrophysics Data System (ADS)

    Binder, B.; Gross, J.; Williams, B. F.; Eracleous, M.; Gaetz, T. J.; Plucinsky, P. P.; Skillman, E. D.

    2017-01-01

    We have obtained three epochs of Chandra ACIS-I observations (totaling ∼184 ks) of the nearby spiral galaxy NGC 300 to study the logN–logS distributions of its X-ray point-source population down to ∼2 × 10‑15 erg s‑1 cm‑2 in the 0.35–8 keV band (equivalent to ∼1036 erg s‑1). The individual epoch logN–logS distributions are best described as the sum of a background active galactic nucleus (AGN) component, a simple power law, and a broken power law, with the shape of the logN–logS distributions sometimes varying between observations. The simple power law and AGN components produce a good fit for “persistent” sources (i.e., with fluxes that remain constant within a factor of ∼2). The differential power-law index of ∼1.2 and high fluxes suggest that the persistent sources intrinsic to NGC 300 are dominated by Roche-lobe-overflowing low-mass X-ray binaries. The variable X-ray sources are described by a broken power law, with a faint-end power-law index of ∼1.7, a bright-end index of ∼2.8–4.9, and a break flux of ∼ 8× {10}-15 erg s‑1 cm‑2 (∼4 × 1036 erg s‑1), suggesting that they are mostly outbursting, wind-fed high-mass X-ray binaries, although the logN–logS distribution of variable sources likely also contains low-mass X-ray binaries. We generate model logN–logS distributions for synthetic X-ray binaries and constrain the distribution of maximum X-ray fluxes attained during outburst. Our observations suggest that the majority of outbursting X-ray binaries occur at sub-Eddington luminosities, where mass transfer likely occurs through direct wind accretion at ∼1%–3% of the Eddington rate.

  9. The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

    NASA Astrophysics Data System (ADS)

    Reylé, C.; Delorme, P.; Willott, C. J.; Albert, L.; Delfosse, X.; Forveille, T.; Artigau, E.; Malo, L.; Hill, G. J.; Doyon, R.

    2010-11-01

    Context. Thanks to recent and ongoing large scale surveys, hundreds of brown dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam camera on the Canada-France-Hawaii Telescope. Aims: Our objectives are to find ultracool brown dwarfs and to constrain the field brown-dwarf luminosity function and the mass function from a large and homogeneous sample of L and T dwarfs. Methods: We identify candidates in CFHT/MegaCam i' and z' images and follow them up with pointed near infrared (NIR) imaging on several telescopes. Halfway through our survey we found ~50 T dwarfs and ~170 L or ultra cool M dwarfs drawn from a larger sample of 1400 candidates with typical ultracool dwarfs i'-z' colours, found in 780 square degrees. Results: We have currently completed the NIR follow-up on a large part of the survey for all candidates from mid-L dwarfs down to the latest T dwarfs known with utracool dwarfs' colours. This allows us to draw on a complete and well defined sample of 102 ultracool dwarfs to investigate the luminosity function and space density of field dwarfs. Conclusions: We found the density of late L5 to T0 dwarfs to be 2.0+0.8-0.7 × 10-3 objects pc-3, the density of T0.5 to T5.5 dwarfs to be 1.4+0.3-0.2 × 10-3 objects pc-3, and the density of T6 to T8 dwarfs to be 5.3+3.1-2.2 × 10-3 objects pc-3. We found that these results agree better with a flat substellar mass function. Three latest dwarfs at the boundary between T and Y dwarfs give the high density 8.3+9.0-5.1 × 10-3 objects pc-3. Although the uncertainties are very large this suggests that many brown dwarfs should be found in this late spectral type range, as expected from the cooling of brown dwarfs, whatever their mass, down to very low temperature. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by

  10. First results from the VIMOS/VLT Deep Survey (VVDS): luminosity functions from z˜0 to z˜1.5

    NASA Astrophysics Data System (ADS)

    Zucca, E.; Ilbert, O.; Tresse, L.; Bardelli, S.; Arnouts, S.; Zamorani, G.; Le Fèvre, O.; Vettolani, G.; Adami, C.; sBolzonella, M.; Bondi, M.; Bongiorno, A.; Bottini, D.; Busarello, G.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Garilli, B.; Gavignaud, I.; Gregorini, L.; Guzzo, L.; Iovino, A.; Le Brun, V.; Maccagni, D.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; McCracken, H. J.; Mellier, Y.; Meneux, B.; Merighi, R.; Merluzzi, P.; Paltani, S.; Pellò, R.; Picat, J. P.; Pollo, A.; Pozzetti, L.; Radovich, M.; Ripepi, V.; Rizzo, D.; Scaramella, R.; Scodeggio, M.; Zanichelli, A.

    The VIMOS/VLT Deep Survey (VVDS) is an on-going program to map the evolution of galaxies, large scale structures and AGNs from the redshift measurement of more than 100000 objects down to a magnitude IAB=24, in combination with a multi-wavelength dataset from radio to X-rays. We present here the results obtained from the first epoch data, regarding in particular the evolution of the luminosity function.

  11. A MULTICOLOR PHOTOMETRIC STUDY OF THE GALAXY CLUSTER A2589: DYNAMICS, LUMINOSITY FUNCTION, AND STAR FORMATION HISTORY

    SciTech Connect

    Liu Shunfang; Yang Yanbin; Ma Jun; Jiang Zhaoji; Wu Jianghua; Wu Zhenyu; Chen Jiansheng; Zhou Xu; Yuan Qirong E-mail: zhouxu@bao.ac.cn

    2011-03-15

    Smooth X-ray morphology and non-detection of a radio source at the center of A2589 indicate that it is a typical case of a well-relaxed regular galaxy cluster. In this paper, we present a multicolor photometry for A2589 (z = 0.0414) with 15 intermediate bands in the Beijing-Arizona-Taiwan-Connecticut (BATC) system which covers an optical wavelength range from 3000 A to 10000 A. The spectral energy distributions (SEDs) for more than 5000 sources are achieved down to V {approx} 20 mag in about a 1 deg{sup 2} field. A2589 has also been covered by the Sloan Digital Sky Survey (SDSS) in photometric mode only. A cross-identification of the BATC-detected galaxies with the SDSS photometric catalog yields 1199 galaxies brighter than i = 19.5 mag, among which 68 member galaxies with known spectroscopic redshifts are found. After combining the SDSS five-band photometric data and the BATC SEDs, photometric redshift is applied to these galaxies to select faint member galaxies. The color-magnitude relation is taken as a further restriction of early-type cluster galaxies. As a result, 106 galaxies are newly selected as member galaxies. Spatial distribution of member galaxies shows a north-south elongation which agrees with the X-ray brightness profile and the orientation of central cD galaxy, NGC 7647. No substructures are detected on the basis of positions and radial velocities of cluster galaxies, indicating that A2589 is a well-relaxed system. The luminosity function of A2589 exhibits a peak at M{sub R} {approx} -20 mag and a dip at M{sub R} {approx} -19 mag. The low-density outer regions are the preferred habitat of faint galaxies. With the evolutionary population synthesis model, PEGASE, the environmental effect on the star formation properties for 68 spectroscopically confirmed member galaxies is studied. The outlier faint galaxies tend to have longer timescales of star formation, shorter mean stellar ages, and lower metallicities in the interstellar medium, which can be

  12. The VIMOS-VLT Deep Survey. Galaxy luminosity function per morphological type up to z = 1.2

    NASA Astrophysics Data System (ADS)

    Ilbert, O.; Lauger, S.; Tresse, L.; Buat, V.; Arnouts, S.; Le Fèvre, O.; Burgarella, D.; Zucca, E.; Bardelli, S.; Zamorani, G.; Bottini, D.; Garilli, B.; Le Brun, V.; Maccagni, D.; Picat, J.-P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Bolzonella, M.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; Meneux, B.; Merighi, R.; Paltani, S.; Pello, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Bondi, M.; Bongiorno, A.; Busarello, G.; Ciliegi, P.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.

    2006-07-01

    Aims.We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z=1.2. Methods: .We use a sample of 605 spectroscopic redshifts with IAB≤ 24 in the Chandra Deep Field South from the VIMOS-VLT Deep Survey, 3555 galaxies with photometric redshifts from the COMBO-17 multi-color data, coupled with multi-color HST/ACS images from the Great Observatories Origin Deep Survey. We split the sample in bulge- and disk-dominated populations on the basis of asymmetry and concentration parameters measured in the rest-frame B-band. Results: .We find that at z=0.4-0.8, the LF slope is significantly steeper for the disk-dominated population (α=-1.19 ± 0.07) compared to the bulge-dominated population (α=-0.53 ± 0.13). The LF of the bulge-dominated population is composed of two distinct populations separated in rest-frame color: 68% of red (B-I)AB>0.9 and bright galaxies showing a strongly decreasing LF slope α=+0.55 ± 0.21, and 32% of blue (B-I)AB<0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z≃1, but the volume density of this population is increasing by a factor 2.7 between z˜ 1 and z˜ 0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 mag between z˜ 1 and z˜ 0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.

  13. A Markov Chain Monte Carlo Software Package to Constrain the Evolution of Luminosity Functions, Test SED Models, and Simulate Future Surveys

    NASA Astrophysics Data System (ADS)

    Kurinsky, Noah; Sajina, Anna

    2014-06-01

    We present a novel simulation and fitting program which employs MCMC to constrain the spectral energy distribution makeup and luminosity function evolution required to produce a given mutli-wavelength survey. This tool employs a multidimensional color-color diagnostic to determine goodness of fit, and simulates observational sources of error such as flux-limits and instrumental noise. Our goals in designing this tool were to a) use it to study Infrared surveys and test SED template models, and b) create it in such a way as to make it usable in any electromagnetic regime for any class of sources to which any luminosity functional form can be prescribed.I will discuss our specific use of the program to characterize a survey from the Herschel SPIRE HerMES catalog, including implications for our luminosity function and SED models. I will also briefly discuss the ways we envision using it for simulation and application to other surveys, and I will demonstrate the degree to which its reusability can serve to enrich a wide range of analyses.

  14. Evolution of the Observed Ly-alpha Luminosity Function from z = 6.5 to z = 7.7: Evidence for the Epoch of Re-ionisation?

    NASA Astrophysics Data System (ADS)

    Clément, B.; Cuby, J.-G.; Courbin, F.; Fontana, A.; Freudling, W.; Fynbo, J.; Gallego, J.; Hibon, P.; Kneib, J.-P.; Le Fèvre, O.; Lidman, C.; McMahon, R.; Milvang-Jensen, B.; Moller, P.; Nilsson, K. K.; Pentericci, L.; Venemans, B.; Villar, V.; Willis, J.

    2011-12-01

    Probing the first billion years of the Universe is one of the last frontiers in cosmology. Ly-alpha emitters (LAEs) are galaxies that can be detected out to very high redshifts during the epoch of re-ionisation. The evolution of their luminosity function with redshift is a direct probe of the Ly-alpha transmission of the intergalactic medium (IGM), related to the amount of neutral hydrogen. We report on the results of a search for LAEs at z = 7.7 using HAWK-I at the VLT with a narrowband filter centred at 1.06 μm. We did not find any LAE candidates, which allows us to infer robust constraints on the LAE luminosity function at z = 7.7. Depending on which luminosity functions at z = 6.5 are referred to, our results may reflect a significant quenching of the IGM Ly-alpha transmission, possibly from a strong increase in the neutral hydrogen fraction between these two redshifts.

  15. Short-time variations of the solar neutrino luminosity Fourier analysis of the Argon-37 production rate data

    NASA Astrophysics Data System (ADS)

    Haubold, H. J.; Gorth, E.

    1985-01-01

    The authors continue the Fourier analysis of the argon-37 production rate for runs 18 - 80 observed in Davis' well known solar neutrino experiment. The method of Fourier analysis with the unequally-spaced data of Davis and associates is described and the discovered periods compared with the authors' recently published results for the analysis of runs 18 - 69 (Haubold and Gerth, 1983). The harmonic analysis of the data of runs 18 - 80 shows time variations of the solar neutrino flux with periods π = 8.33; 5.26; 2.13; 1.56; 0.83; 0.64; 0.54; and 0.50 years, respectively, which confirm the authors' earlier computations.

  16. ULTRAVIOLET LUMINOSITY FUNCTIONS FROM 132 z {approx} 7 AND z {approx} 8 LYMAN-BREAK GALAXIES IN THE ULTRA-DEEP HUDF09 AND WIDE-AREA EARLY RELEASE SCIENCE WFC3/IR OBSERVATIONS

    SciTech Connect

    Bouwens, R. J.; Illingworth, G. D.; Magee, D.; Gonzalez, V.; Labbe, I.; Trenti, M.; Van Dokkum, P.; Franx, M.; Stiavelli, M.

    2011-08-20

    We identify 73 z {approx} 7 and 59 z {approx} 8 candidate galaxies in the reionization epoch, and use this large 26-29.4 AB mag sample of galaxies to derive very deep luminosity functions to < - 18 AB mag and the star formation rate (SFR) density at z {approx} 7 and z {approx} 8 (just 800 Myr and 650 Myr after recombination, respectively). The galaxy sample is derived using a sophisticated Lyman-break technique on the full two-year Wide Field Camera 3/infrared (WFC3/IR) and Advanced Camera for Surveys (ACS) data available over the HUDF09 ({approx}29.4 AB mag, 5{sigma}), two nearby HUDF09 fields ({approx}29 AB mag, 5{sigma}, 14 arcmin{sup 2}), and the wider area Early Release Science ({approx}27.5 AB mag, 5{sigma}, {approx}40 arcmin{sup 2}). The application of strict optical non-detection criteria ensures the contamination fraction is kept low (just {approx}7% in the HUDF). This very low value includes a full assessment of the contamination from lower redshift sources, photometric scatter, active galactic nuclei, spurious sources, low-mass stars, and transients (e.g., supernovae). From careful modeling of the selection volumes for each of our search fields, we derive luminosity functions for galaxies at z {approx} 7 and z {approx} 8 to < - 18 AB mag. The faint-end slopes {alpha} at z {approx} 7 and z {approx} 8 are uncertain but very steep at {alpha} = -2.01 {+-} 0.21 and {alpha} = -1.91 {+-} 0.32, respectively. Such steep slopes contrast to the local {alpha} {approx}> -1.4 and may even be steeper than that at z {approx} 4 where {alpha} = -1.73 {+-} 0.05. With such steep slopes ({alpha} {approx}< -1.7) lower luminosity galaxies dominate the galaxy luminosity density during the epoch of reionization. The SFR densities derived from these new z {approx} 7 and z {approx} 8 luminosity functions are consistent with the trends found at later times (lower redshifts). We find reasonable consistency with the SFR densities implied from reported stellar mass densities being

  17. The high-mass end of the red sequence at z ˜ 0.55 from SDSS-III/BOSS: completeness, bimodality and luminosity function

    NASA Astrophysics Data System (ADS)

    Montero-Dorta, Antonio D.; Bolton, Adam S.; Brownstein, Joel R.; Swanson, Molly; Dawson, Kyle; Prada, Francisco; Eisenstein, Daniel; Maraston, Claudia; Thomas, Daniel; Comparat, Johan; Chuang, Chia-Hsun; McBride, Cameron K.; Favole, Ginevra; Guo, Hong; Rodríguez-Torres, Sergio; Schneider, Donald P.

    2016-09-01

    We have developed an analytical method based on forward-modelling techniques to characterize the high-mass end of the red sequence (RS) galaxy population at redshift z ˜ 0.55, from the DR10 BOSS (Baryon Oscillation Spectroscopic Survey) CMASS spectroscopic sample, which comprises ˜600 000 galaxies. The method, which follows an unbinned maximum likelihood approach, allows the deconvolution of the intrinsic CMASS colour-colour-magnitude distributions from photometric errors and selection effects. This procedure requires modelling the covariance matrix for the i-band magnitude, g - r colour and r - i colour using Stripe 82 multi-epoch data. Our results indicate that the error-deconvolved intrinsic RS distribution is consistent, within the photometric uncertainties, with a single point (<0.05 mag) in the colour-colour plane at fixed magnitude, for a narrow redshift slice. We have computed the high-mass end (0.55Mi ≲ -22) of the 0.55i-band RS luminosity function (RS LF) in several redshift slices within the redshift range 0.52 < z < 0.63. In this narrow redshift range, the evolution of the RS LF is consistent, within the uncertainties in the modelling, with a passively evolving model with Φ* = (7.248 ± 0.204) × 10- 4 Mpc-3 mag-1, fading at a rate of 1.5 ± 0.4 mag per unit redshift. We report RS completeness as a function of magnitude and redshift in the CMASS sample, which will facilitate a variety of galaxy-evolution and clustering studies using BOSS. Our forward-modelling method lays the foundations for future studies using other dark-energy surveys like the Extended Baryon Oscillation Spectroscopic Survey or the Dark Energy Spectroscopic Instrument, which are affected by the same type of photometric blurring/selection effects.

  18. The galaxy luminosity function at z ≃ 6 and evidence for rapid evolution in the bright end from z ≃ 7 to 5

    NASA Astrophysics Data System (ADS)

    Bowler, R. A. A.; Dunlop, J. S.; McLure, R. J.; McCracken, H. J.; Milvang-Jensen, B.; Furusawa, H.; Taniguchi, Y.; Le Fèvre, O.; Fynbo, J. P. U.; Jarvis, M. J.; Häußler, B.

    2015-09-01

    We present the results of a search for bright (-22.7 ≤ MUV ≤ -20.5) Lyman-break galaxies at z ≃ 6 within a total of 1.65 deg2 of imaging in the UltraVISTA/Cosmological Evolution Survey (COSMOS) and United Kingdom Infrared Telescope Deep Sky Survey (UKIDSS) Ultra Deep Survey (UDS) fields. The deep near-infrared imaging available in the two independent fields, in addition to deep optical (including z'-band) data, enables the sample of z ≃ 6 star-forming galaxies to be securely detected longward of the break (in contrast to several previous studies). We show that the expected contamination rate of our initial sample by cool Galactic brown dwarfs is ≲3 per cent and demonstrate that they can be effectively removed by fitting brown dwarf spectral templates to the photometry. At z ≃ 6, the galaxy surface density in the UltraVISTA field exceeds that in the UDS by a factor of ≃ 1.8, indicating strong cosmic variance even between degree-scale fields at z > 5. We calculate the bright end of the rest-frame Ultraviolet (UV) luminosity function (LF) at z ≃ 6. The galaxy number counts are a factor of ˜1.7 lower than predicted by the recent LF determination by Bouwens et al. In comparison to other smaller area studies, we find an evolution in the characteristic magnitude between z ≃ 5 and z ≃ 7 of ΔM* ˜ 0.4, and show that a double power law or a Schechter function can equally well describe the LF at z = 6. Furthermore, the bright end of the LF appears to steepen from z ≃ 7 to z ≃ 5, which could indicate the onset of mass quenching or the rise of dust obscuration, a conclusion supported by comparing the observed LFs to a range of theoretical model predictions.

  19. 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

    NASA Astrophysics Data System (ADS)

    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 <= 22.5 galaxies selected over an area of 0.6 deg2 from the Early Data Release of the UKIDSS 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. However, the strength of the colour bimodality is found to be a decreasing function of redshift, and seems to disappear by 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 <= - 23) stays approximately constant with redshift, and that these sources dominate the bright end of the LF at redshifts z <~ 1. In contrast, the brightening of the characteristic luminosity and mild decrease in space density displayed by the blue galaxy population leads them to dominate the bright end of the LF at redshifts z >~ 1.

  20. The star formation rate cookbook at 1 < z < 3: Extinction-corrected relations for UV and [OII]λ3727 luminosities

    NASA Astrophysics Data System (ADS)

    Talia, M.; Cimatti, A.; Pozzetti, L.; Rodighiero, G.; Gruppioni, C.; Pozzi, F.; Daddi, E.; Maraston, C.; Mignoli, M.; Kurk, J.

    2015-10-01

    Aims: In this paper we use a well-controlled spectroscopic sample of galaxies at 1 rate (SFR) estimators. In particular, we use infrared (IR) data to derive empirical calibrations to correct ultraviolet (UV) and [OII]λ3727 luminosities for dust extinction and dust-corrected estimates of SFR. Methods: We selected 286 star-forming galaxies with spectroscopic redshift 1 luminosity (LIR) and continuum reddening. Using Spitzer-MIPS and Herschel-PACS data we derive LIR for two-thirds of our sample. The LIR/LUV ratio is used as a probe of effective attenuation (AIRX) to search for correlations with continuum and spectroscopic features in order to derive empirical calibrations to correct UV and [OII]λ3727 luminosities for dust extinction. Results: Through the analyses of the correlations between different dust attenuation probes, a set of relations is provided that allows the recovery of the total unattenuated SFR for star-forming galaxies at 1 luminosities. The relation between AIRX and UV continuum slope (β) was tested for our sample and found to be broadly consistent with the literature results at the same redshift, though with a larger dispersion with respect to UV-selected samples. We find a correlation between the rest

  1. The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23

    NASA Astrophysics Data System (ADS)

    Sobral, David; Matthee, Jorryt; Best, Philip; Stroe, Andra; Röttgering, Huub; Oteo, Iván; Smail, Ian; Morabito, Leah; Paulino-Afonso, Ana

    2017-04-01

    We present the CAlibrating LYMan-α with Hα (CALYMHA) pilot survey and new results on Lyman α (Lyα) selected galaxies at z ˜ 2. We use a custom-built Lyα narrow-band filter at the Isaac Newton Telescope, designed to provide a matched volume coverage to the z = 2.23 Hα HiZELS survey. Here, we present the first results for the COSMOS and UDS fields. Our survey currently reaches a 3σ line flux limit of ˜4 × 10-17 erg s-1 cm-2, and a Lyα luminosity limit of ˜1042.3 erg s-1. We find 188 Lyα emitters over 7.3 × 105 Mpc3, but also find significant numbers of other line-emitting sources corresponding to He II, C III] and C IV emission lines. These sources are important contaminants, and we carefully remove them, unlike most previous studies. We find that the Lyα luminosity function at z = 2.23 is very well described by a Schechter function up to LLy α ≈ 1043 erg s-1 with L^{ast }=10^{42.59^{+0.16}_{-0.08}} erg s-1, φ ^{ast }=10^{-3.09^{+0.14}_{-0.34}} Mpc-3 and α = -1.75 ± 0.25. Above LLy α ≈ 1043 erg s-1, the Lyα luminosity function becomes power-law like, driven by X-ray AGN. We find that Lyα-selected emitters have a high escape fraction of 37 ± 7 per cent, anticorrelated with Lyα luminosity and correlated with Lyα equivalent width. Lyα emitters have ubiquitous large (≈40 kpc) Lyα haloes, ˜2 times larger than their Hα extents. By directly comparing our Lyα and Hα luminosity functions, we find that the global/overall escape fraction of Lyα photons (within a 13 kpc radius) from the full population of star-forming galaxies is 5.1 ± 0.2 per cent at the peak of the star formation history. An extra 3.3 ± 0.3 per cent of Lyα photons likely still escape, but at larger radii.

  2. The faint end of the red sequence galaxy luminosity function: unveiling surface brightness selection effects with the CLASH clusters

    NASA Astrophysics Data System (ADS)

    Martinet, Nicolas; Durret, Florence; Adami, Christophe; Rudnick, Gregory

    2017-08-01

    Characterizing the evolution of the faint end of the cluster red sequence (RS) galaxy luminosity function (GLF) with redshift is a milestone in understanding galaxy evolution. However, the community is still divided in that respect, hesitating between an enrichment of the RS due to efficient quenching of blue galaxies from z 1 to present-day or a scenario in which the RS is built at a higher redshift and does not evolve afterwards. Recently, it has been proposed that surface brightness (SB) selection effects could possibly solve the literature disagreement, accounting for the diminishing RS faint population in ground-based observations. We investigate this hypothesis by comparing the RS GLFs of 16 CLASH clusters computed independently from ground-based Subaru/Suprime-Cam V and Ip or Ic images and space-based HST/ACS F606W and F814W images in the redshift range 0.187 ≤ z ≤ 0.686. We stack individual cluster GLFs in two redshift bins (0.187 ≤ z ≤ 0.399 and 0.400 ≤ z ≤ 0.686) and two mass (6 × 1014M⊙ ≤ M200< 1015M⊙ and 1015M⊙ ≤ M200) bins, and also measure the evolution with the enclosing radius from 0.5 Mpc up to the virial radius for the Subaru large field of view data. Finally, we simulate the low-redshift clusters at higher redshift to investigate SB dimming effects. We find similar RS GLFs for space- and ground-based data, with a difference of 0.2σ in the faint end parameter α when stacking all clusters together and a maximum difference of 0.9σ in the case of the high-redshift stack, demonstrating a weak dependence on the type of observation in the probed range of redshift and mass. When considering the full sample, we estimate α = - 0.76 ± 0.07 and α = - 0.78 ± 0.06 with HST and Subaru, respectively. We note a mild variation of the faint end between the high- and low-redshift subsamples at a 1.7σ and 2.6σ significance. We investigate the effect of SB dimming by simulating our low-redshift galaxies at high redshift. We measure an

  3. A WISE Measurement of the 2:4 mum Galaxy Luminosity Function and its Implications for the Extragalactic Background Light at 3:4 mum

    NASA Astrophysics Data System (ADS)

    Lake, Sean Earl

    2017-05-01

    The measurement of the the Extragalactic Background Light (EBL) has seen some controversy in recent works, with direct and indirect measures conflicting. Specifi- cally, upper limits based on analyzing the plausible opacity obscuring TeV spectra of blazars suggests that the density of radiation with wavelengths near 3.4 mum is onethirdtoonehalfasintenseasdirectmeasuresofthesame(forexample: Aharonian et al., 2006; Levenson et al., 2007; Matsumoto et al., 2005). The dominant contributor of the EBL at 3.4mum is expected to be ordinary starlight from relatively local, z < 1, galaxies, so an estimate of the amount of light emitted by galaxies based on the galaxy Luminosity Function (LF) should provide a useful lower limit to the EBL. While analyses of this sort have been done by others (Dominguez et al., 2011; Helgason et al., 2012), the full sky coverage of the AllWISE database has made it possible for us to improve the measurement of both the LF at 2.4 mum and the EBL using the large public spectroscopic redshift surveys. In order to do so, we had to develop a mathematical model for the measurement of a generalization of the LF, which is the density of galaxies per unit comoving volume per unit luminosity, to the Spectro-Luminosity Functional (SLF), which replaces the density per unit single luminosity, dL, with the density per luminosi- ii ties at all frequencies, DL nu. Our best combined analysis of the data yields present day Shechter Function LF parameters of: L⋆ = 6.4+/-[0.1 stat, 0.3sys]x1010 L2.4mum [solar mass](M⋆ = -21.67+/-[0.02 stat, 0.05sys] AB mag), φ⋆ = 5.8+/-[0.3stat, 0.3sys]x10 -3 Mpc-3, and alpha = -1.050 +/- [0.004stat, 0.03sys]; this implies a present day density of galaxies of 0.08 Mpc-3 brighter that 106 L2.4mum [solar mass] (10-3 Mpc-3 brighter than L⋆) and a luminosity density equivalent to 3.8 x 108 L2.4mum [solar mass] Mpc-3. The net EBL at 3.4mum that our synthesis model produces from galaxies closer than z = 5 is Inu = 9.0 +/- 0.5 k

  4. Testing Design and Response of Multi-anode Photo-multiplier Tubes in High-rate Environments for Use in Future High-luminosity Experiments

    NASA Astrophysics Data System (ADS)

    Paolone, Michael; Meziani, Zein-Eddine; Joosten, Sylvester; Rehfuss, Melanie; Duran, Burcu

    2016-09-01

    As future experiments are designed on the edge of the high luminosity frontier, such as the proposed experiments for the SoLID detector at Jefferson Lab or the EIC, development of stable and efficient detectors capable of handling a high rate environment is crucial to their success. Multi-anode photo-multiplier tubes (MaPMTs), as a newer technology that is sensitive to the spatial distribution of intensity across its surface, are replacing traditional tube PMTs in many proposed experimental devices. In comparison to standard quartz-glass PMTs, MaPMT's are more cost effective, can be tiled to cover a detection plane more uniformly, and can be coated with wavelength shifting p-Terphenyl to provide similar detection efficiency in the UV spectrum. We have designed a prototype Cherenkov to test the capabilities of Hamamatsu 12700C MaPMTs in high rate conditions. Specifics of the Cherenkov detector and electronics design, as well as the response of the MaPMTs, will be presented. This work is supported through DOE Grant DE-FG02-94ER4084.

  5. A Mixture Evolution Scenario of the AGN Radio Luminosity Function. II. Do Low- and High-power Radio-loud AGNs Evolve Differently?

    NASA Astrophysics Data System (ADS)

    Yuan, Zunli; Wang, Jiancheng; Zhou, Ming; Qin, Longhua; Mao, Jirong

    2017-09-01

    Following previous work, we further confirm that the cosmic evolution of steep-spectrum radio-loud AGNs (active galactic nuclei) can be reproduced by a simple combination of density evolution (DE) and luminosity evolution (LE). This mixture evolution scenario can naturally explain the luminosity-dependent evolution of radio-loud AGNs. Our models successfully fitted a large amount of data on radio luminosity functions of steep-spectrum sources and multi-frequency source counts. The modeling indicates that the DE slowly increases as {(1+z)}0.3∼ 1.3 out to z∼ 0.8, and then rapidly decreases as {(1+z)}-6.8∼ -5.7, while the LE rapidly increases as {(1+z)}4.8 out to a higher redshift (at least z> 3.5). We find a high-redshift decline (i.e., redshift cutoff) in the number density of steep-spectrum radio sources, but we cannot conclude whether such a decline is sharp or shallow. We believe that whether a redshift cutoff occurs or not depends mainly on DE, while its steepness is decided by LE, which, however, cannot be well constrained due to the lack of high-redshift samples. Most intriguingly, according to our mixture evolution scenario, there appears to be no need for different evolution for the low- and high-power radio-loud AGNs. Both types of sources experience the same combined evolution of DE and LE.

  6. Luminosity monitor at PEP

    SciTech Connect

    Fox, J.D.; Franklin, M.E.B.

    1981-02-01

    The luminosity monitor system utilized by the MKII Detector and by the PEP operators is described. This system processes information from 56 photomultipliers and calculates independent luminosities for each of the 3 colliding bunches in PEP. Design considerations, measurement techniques, and sources of error in the luminosity measurement are discussed.

  7. Stellar Populations in the Central 0.5 pc of the Galaxy. I. A New Method for Constructing Luminosity Functions and Surface-density Profiles

    NASA Astrophysics Data System (ADS)

    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.

  8. STELLAR POPULATIONS IN THE CENTRAL 0.5 pc OF THE GALAXY. I. A NEW METHOD FOR CONSTRUCTING LUMINOSITY FUNCTIONS AND SURFACE-DENSITY PROFILES

    SciTech Connect

    Do, T.; Martinez, G. D.; Lu, J. R.; Ghez, A. M.; Morris, M. R.; Yelda, S.; Wright, S. A.; Matthews, K.

    2013-02-20

    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 {approx}10 M {sub Sun} 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, {Sigma}(R){proportional_to}R {sup -{Gamma}}, for the young stars and late-type giants are consistent with earlier results ({Gamma}{sub early} = 0.93 {+-} 0.09, {Gamma}{sub late} = 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.

  9. On the determination of age and mass functions of stars in young open star clusters from the analysis of their luminosity functions

    NASA Astrophysics Data System (ADS)

    Piskunov, A. E.; Belikov, A. N.; Kharchenko, N. V.; Sagar, R.; Subramaniam, A.

    2004-04-01

    We construct the observed luminosity functions of the remote young open clusters NGC 2383, 2384, 4103, 4755, 7510 and Hogg 15 from CCD observations of them. The observed LFs are corrected for field star contamination determined with the help of a Galactic star count model. In the case of Hogg 15 and NGC 2383 we also consider the additional contamination from neighbouring clusters NGC 4609 and 2384, respectively. These corrections provide a realistic pattern of cluster LF in the vicinity of the main-sequence (MS) turn-on point and at fainter magnitudes reveal the so-called H-feature arising as a result of the transition of the pre-MS phase to the MS, which is dependent on the cluster age. The theoretical LFs are constructed representing a cluster population model with continuous star formation for a short time-scale and a power-law initial mass function (IMF), and these are fitted to the observed LF. As a result, we are able to determine for each cluster a set of parameters describing the cluster population (the age, duration of star formation, IMF slope and percentage of field star contamination). It is found that in spite of the non-monotonic behaviour of observed LFs, cluster IMFs can be described as power-law functions with slopes similar to Salpeter's value. The present main-sequence turn-on cluster ages are several times lower than those derived from the fitting of theoretical isochrones to the turn-off region of the upper main sequences.

  10. Evolution of the observed Lyα luminosity function from z = 6.5 to z = 7.7: evidence for the epoch of reionization?

    NASA Astrophysics Data System (ADS)

    Clément, B.; Cuby, J.-G.; Courbin, F.; Fontana, A.; Freudling, W.; Fynbo, J.; Gallego, J.; Hibon, P.; Kneib, J.-P.; Le Fèvre, O.; Lidman, C.; McMahon, R.; Milvang-Jensen, B.; Moller, P.; Moorwood, A.; Nilsson, K. K.; Pentericci, L.; Venemans, B.; Villar, V.; Willis, J.

    2012-02-01

    Aims: Lyα emitters (LAEs) can be detected out to very high redshifts during the epoch of reionization. The evolution of the LAE luminosity function with redshift is a direct probe of the Lyα transmission of the intergalactic medium (IGM), and therefore of the IGM neutral-hydrogen fraction. Measuring the Lyα luminosity function (LF) of Lyα emitters at redshift z = 7.7 therefore allows us to constrain the ionizing state of the Universe at this redshift. Methods: We observed three 7'.5 × 7'.5 fields with the HAWK-I instrument at the VLT with a narrow band filter centred at 1.06 μm and targeting Lyα emitters at redshift z ~ 7.7. The fields were chosen for the availability of multiwavelength data. One field is a galaxy cluster, the Bullet Cluster, which allowed us to use gravitational amplification to probe luminosities that are fainter than in the field. The two other fields are subareas of the GOODS Chandra Deep Field South and CFHTLS-D4 deep field. We selected z = 7.7 LAE candidates from a variety of colour criteria, in particular from the absence of detection in the optical bands. Results: We do not find any LAE candidates at z = 7.7 in ~2.4 × 104 Mpc3 down to a narrow band AB magnitude of ~26, which allows us to infer robust constraints on the Lyα LAE luminosity function at this redshift. Conclusions: The predicted mean number of objects at z = 6.5, derived from somewhat different luminosity functions of Hu et al. (2010, ApJ, 725, 394), Ouchi et al. (2010, ApJ, 723, 869), and Kashikawa et al. (2011, ApJ, 734, 119) are 2.5, 13.7, and 11.6, respectively. Depending on which of these luminosity functions we refer to, we exclude a scenario with no evolution from z = 6.5 to z = 7.7 at 85% confidence without requiring a strong change in the IGM Lyα transmission, or at 99% confidence with a significant quenching of the IGM Lyα transmission, possibly from a strong increase in the high neutral-hydrogen fraction between these two redshifts. Based on observations

  11. THE X-RAY LUMINOSITY FUNCTION OF LOW MASS X-RAY BINARIES IN EARLY-TYPE GALAXIES, THEIR METAL-RICH, AND METAL-POOR GLOBULAR CLUSTERS

    SciTech Connect

    Peacock, Mark B.; Zepf, Stephen E.

    2016-02-10

    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-type 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{sup 37}–10{sup 38} erg s{sup −1}, and Hubble Space Telescope optical mosaics that 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 affect 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 × 10{sup −6} (equivalent to 4.7σ for a normal distribution). The difference is such that the XLF of the GC LMXBs is flatter than that of the field LMXBs, with the GCs hosting relatively more bright sources and fewer faint sources. A comparison of the XLF of the metal-rich and metal-poor GCs hints that the metal-poor clusters may have more bright LMXBs, but the difference is not statistically significant.

  12. THE LBT BOOeTES FIELD SURVEY. I. THE REST-FRAME ULTRAVIOLET AND NEAR-INFRARED LUMINOSITY FUNCTIONS AND CLUSTERING OF BRIGHT LYMAN BREAK GALAXIES AT Z {approx} 3

    SciTech Connect

    Bian Fuyan; Fan Xiaohui; Jiang Linhua; McGreer, Ian; Dave, Romeel; Dey, Arjun; Green, Richard F.; Maiolino, Roberto; Walter, Fabian; Lee, Kyoung-Soo

    2013-09-01

    We present a deep LBT/LBC U{sub spec}-band imaging survey (9 deg{sup 2}) covering the NOAO Booetes field. A total of 14,485 Lyman break galaxies (LBGs) at z {approx} 3 are selected, which are used to measure the rest-frame UV luminosity function (LF). The large sample size and survey area reduce the LF uncertainties due to Poisson statistics and cosmic variance by {>=}3 compared to previous studies. At the bright end, the LF shows excess power compared to the best-fit Schechter function, which can be attributed to the contribution of z {approx} 3 quasars. We compute the rest-frame near-infrared LF and stellar mass function (SMF) of z {approx} 3 LBGs based on the R-band and [4.5 {mu}m]-band flux relation. We investigate the evolution of the UV LFs and SMFs between z {approx} 7 and z {approx} 3, which supports a rising star formation history in the LBGs. We study the spatial correlation function of two bright LBG samples and estimate their average host halo mass. We find a tight relation between the host halo mass and the galaxy star formation rate (SFR), which follows the trend predicted by the baryonic accretion rate onto the halo, suggesting that the star formation in LBGs is fueled by baryonic accretion through the cosmic web. By comparing the SFRs with the total baryonic accretion rates, we find that cosmic star formation efficiency is about 5%-20% and it does not evolve significantly with redshift, halo mass, or galaxy luminosity.

  13. Star formation rates as a function of galaxy mass

    NASA Technical Reports Server (NTRS)

    Romanishin, W.

    1987-01-01

    Correlations were found between the colors and absolute magnitudes of spiral galaxies. Using optical and/or near IR (1.6 micron) colors, it was found that lower luminosity spirals are systematically bluer than higher luminosity spirals. Infrared Astronomy Satellite (IRAS) far IR luminosities were used to investigate the suggestion that one prime cause of these color-absolute magnitude correlations is a systematic variation with galaxy mass of the current star formation rate (SFR) per unit mass. To the extent that the IRAS fluxes actually measure disk SFR, no correlation of SFR/unit mass and galaxy mass was found. Other possible explanations of the color-absolute magnitude correlations are discussed, as well as caveats on the use of IRAS fluxes as a means of comparing SFRs in galaxies of differing mass.

  14. Evolutionary variations of solar luminosity

    NASA Technical Reports Server (NTRS)

    Endal, A. S.

    1981-01-01

    Theoretical arguments for a 30% increase in the solar luminosity over the past 4.7 billion years are reviewed. A scaling argument shows that this increase can be predicted without detailed numerical calculations. The magnitude of the increase is independent of nuclear reaction rates, as long as conversion of hydrogen to helium provides the basic energy source of the Sun. The effect of the solar luminosity increase on the terrestrial climate is briefly considered. It appears unlikely that an enhanced greenhouse effect, due to reduced gases (NH3, CH4), can account for the long-term paleoclimatic trends.

  15. Distribution of Luminosity, Gas, and Stellar Populations in Local Luminous Infrared Galaxies as a Function of Merger Stage

    NASA Astrophysics Data System (ADS)

    Larson, Kirsten L.

    Luminous infrared galaxies (LIRGs) are galaxies where intense infrared emission is driven by star formation and active galactic nuclei. In the local universe it is clear that many LIRGs are major mergers of gas rich spiral galaxies. I have performed a careful visual classification of local (z < 0.08) LIRGs as either single non-interacting systems, minor mergers, or one of 5 major merger stages. I then used these classifications to compare galaxy merger stage with molecular gas mass, automated morphology parameters, annular optical B -- I colors, and infrared surface brightness profiles. I have found that all sources above an infrared luminosity of LIR > 1011:5Lsun are merging galaxies, while below this luminosity threshold, minor mergers and secular processes dominate. The mean molecular gas fraction ( MGF = MH2=(M* + MH2)) has an average value of 18+/-2% for non-interacting and early stage major merger LIRGs, which increases to 33±3% for intermediate stage major merger LIRGs. This is consistent with the hypotheses that during the early-mid stages of major mergers, atomic gas (H I) at large galactocentric radii is swept inward where it is converted into molecular gas (H2). The interactions also drive star formation throughout the galaxy as is evident by the blue B -- I color for LIRGs at every merger stage. Late stage mergers show a reddening in their nuclear 2 kpc region, presumably also from increase in nuclear gas and dust as the galaxy nuclei coalesce. Using deep Spitzer 3.6 and 4.5 mum imaging, I find that these interactions form tidal tails and debris that extend out to 80 kpc from the galaxy nuclei. This large scale tidal debris builds up over the course of a major merger and forms up-bending infrared surface brightness profiles. I further investigate the utility of automated morphology parameters and present a refined surface brightness method for gini, M20, and concentration indices. With this new method the M20 parameter correlates with merger stage and

  16. Morphology and Molecular Gas Fractions of Local Luminous Infrared Galaxies as a Function of Infrared Luminosity and Merger Stage

    NASA Astrophysics Data System (ADS)

    Larson, K. L.; Sanders, D. B.; Barnes, J. E.; Ishida, C. M.; Evans, A. S.; U, V.; Mazzarella, J. M.; Kim, D.-C.; Privon, G. C.; Mirabel, I. F.; Flewelling, H. A.

    2016-07-01

    We present a new, detailed analysis of the morphologies and molecular gas fractions (MGFs) for a complete sample of 65 local luminous infrared galaxies from Great Observatories All-Sky Luminous Infrared Galaxies (LIRG) Survey using high resolution I-band images from The Hubble Space Telescope, the University of Hawaii 2.2 m Telescope and the Pan-STARRS1 Survey. Our classification scheme includes single undisturbed galaxies, minor mergers, and major mergers, with the latter divided into five distinct stages from pre-first pericenter passage to final nuclear coalescence. We find that major mergers of molecular gas-rich spirals clearly play a major role for all sources with {L}{IR}\\gt {10}11.5{L}⊙ ; however, below this luminosity threshold, minor mergers and secular processes dominate. Additionally, galaxies do not reach {L}{IR}\\gt {10}12.0{L}⊙ until late in the merger process when both disks are near final coalescence. The mean MGF ({MGF} = {M}{{{H}}2}/({M}* +{M}{{{H}}2})) for non-interacting and early-stage major merger LIRGs is 18 ± 2%, which increases to 33 ± 3%, for intermediate stage major merger LIRGs, consistent with the hypothesis that, during the early-mid stages of major mergers, most of the initial large reservoir of atomic gas (HI) at large galactocentric radii is swept inward where it is converted into molecular gas (H2).

  17. KECK SPECTROSCOPY OF LYMAN-BREAK GALAXIES AND ITS IMPLICATIONS FOR THE UV-CONTINUUM AND Ly{alpha} LUMINOSITY FUNCTIONS AT z > 6

    SciTech Connect

    Jiang Linhua; Egami, Eiichi; Walth, Gregory; Kashikawa, Nobunari; Matsuda, Yuichi; Shimasaku, Kazuhiro; Nagao, Tohru; Ota, Kazuaki; Ouchi, Masami

    2011-12-10

    We present Keck spectroscopic observations of z > 6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z' = 27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Ly{alpha} emission lines at 6 {<=} z {<=} 6.4. The median value of the Ly{alpha} rest-frame equivalent widths (EWs) is {approx}50 A, with four EWs >100 A. This well-defined spectroscopic sample spans a UV-continuum luminosity range of -21.8 {<=} M{sub UV} {<=} -19.5 (0.6 {approx} 5 L*{sub UV}) and a Ly{alpha} luminosity range of (0.3-3) Multiplication-Sign 10{sup 43} erg s{sup -1} (0.3-3 L*{sub Ly{alpha}}). We derive the UV and Ly{alpha} luminosity functions (LFs) from our sample at (z) {approx} 6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 5 < z < 7. Our Ly{alpha} LF is also generally in agreement with the results of Ly{alpha}-emitter surveys at z {approx} 5.7 and 6.6. This study shows that deep spectroscopic observations of LBGs can provide unique constraints on both the UV and Ly{alpha} LFs at z > 6.

  18. HUBBLE FRONTIER FIELDS FIRST COMPLETE CLUSTER DATA: FAINT GALAXIES AT z ∼ 5-10 FOR UV LUMINOSITY FUNCTIONS AND COSMIC REIONIZATION

    SciTech Connect

    Ishigaki, Masafumi; Ouchi, Masami; Ono, Yoshiaki; Kawamata, Ryota; Shimasaku, Kazuhiro; Oguri, Masamune

    2015-01-20

    We present comprehensive analyses of faint dropout galaxies up to z ∼ 10 with the first full-depth data set of the A2744 lensing cluster and parallel fields observed by the Hubble Frontier Fields (HFF) program. We identify 54 dropouts at z ∼ 5-10 in the HFF fields and enlarge the size of the z ∼ 9 galaxy sample obtained to date. Although the number of highly magnified (μ ∼ 10) galaxies is small because of the tiny survey volume of strong lensing, our study reaches the galaxies' intrinsic luminosities comparable to the deepest-field HUDF studies. We derive UV luminosity functions with these faint dropouts, carefully evaluating by intensive simulations the combination of observational incompleteness and lensing effects in the image plane, including magnification, distortion, and multiplication of images, with the evaluation of mass model dependencies. Our results confirm that the faint-end slope, α, is as steep as –2 at z ∼ 6-8 and strengthen the evidence for the rapid decrease of UV luminosity densities, ρ{sub UV}, at z > 8 from the large z ∼ 9 sample. We examine whether the rapid ρ{sub UV} decrease trend can be reconciled with the large Thomson scattering optical depth, τ{sub e}, measured by cosmic microwave background experiments, allowing a large space of free parameters, such as an average ionizing photon escape fraction and a stellar-population-dependent conversion factor. No parameter set can reproduce both the rapid ρ{sub UV} decrease and the large τ {sub e}. It is possible that the ρ{sub UV} decrease moderates at z ≳ 11, that the free parameters significantly evolve toward high z, or that there exist additional sources of reionization such as X-ray binaries and faint active galactic nuclei.

  19. The evolution of the [O II], H β and [O III] emission line luminosity functions over the last nine billions years

    NASA Astrophysics Data System (ADS)

    Comparat, Johan; Zhu, Guangtun; Gonzalez-Perez, 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

    2016-09-01

    Emission line galaxies 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, [O II}] (λ λ 3726,3729) (0.5 < z < 1.3), Hβ (λ4861) (0.3 < z < 0.8) and [O {III}] (λ 5007) (0.3 < z < 0.8). Our measurements are based on 35 639 emission line galaxies and cover a volume of ˜107 Mpc3. We present the first measurement of the Hβ 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 (φ*) of all LFs increase with redshift. Using the Schechter model over the redshift ranges considered, we find that, for [O {II}] emitters, the characteristic luminosity L*(z = 0.5) = 3.2 × 1041 erg s-1 increases by a factor of 2.7 ± 0.2 from z = 0.5 to 1.3; for Hβ emitters L*(z = 0.3) = 1.3 × 1041 erg s-1 increases by a factor of 2.0 ± 0.2 from z = 0.3 to 0.8; and for [O {III}] emitters L*(z = 0.3) = 7.3 × 1041 erg s-1 increases by a factor of 3.5 ± 0.4 from z = 0.3 to 0.8.

  20. A Survey of Luminous High-redshift Quasars with SDSS and WISE. II. the Bright End of the Quasar Luminosity Function at z ≈ 5

    NASA Astrophysics Data System (ADS)

    Yang, Jinyi; Wang, Feige; Wu, Xue-Bing; Fan, Xiaohui; McGreer, Ian D.; Bian, Fuyan; Yi, Weimin; Yang, Qian; Ai, Yanli; Dong, Xiaoyi; Zuo, Wenwen; Green, Richard; Jiang, Linhua; Wang, Shu; Wang, Ran; Yue, Minghao

    2016-09-01

    This is the second paper in a series on a new luminous z ˜ 5 quasar survey using optical and near-infrared colors. Here we present a new determination of the bright end of the quasar luminosity function (QLF) at z ˜ 5. Combining our 45 new quasars with previously known quasars that satisfy our selections, we construct the largest uniform luminous z ˜ 5 quasar sample to date, with 99 quasars in the range of 4.7 ≤ z < 5.4 and -29 < M 1450 ≤ -26.8, within the Sloan Digital Sky Survey (SDSS) footprint. We use a modified 1/V a method including flux limit correction to derive a binned QLF, and we model the parametric QLF using maximum likelihood estimation. With the faint-end slope of the QLF fixed as α = -2.03 from previous deeper samples, the best fit of our QLF gives a flatter bright end slope β = -3.58 ± 0.24 and a fainter break magnitude {M}1450* = -26.98 ± 0.23 than previous studies at similar redshift. Combined with previous work at lower and higher redshifts, our result is consistent with a luminosity evolution and density evolution model. Using the best-fit QLF, the contribution of quasars to the ionizing background at z ˜ 5 is found to be 18%-45% with a clumping factor C of 2-5. Our sample suggests an evolution of radio loud fraction with optical luminosity but no obvious evolution with redshift.

  1. A Multi-Frequency Study of an X-ray Selected Sample of AGN II: Line Emission Studies and the X-ray Luminosity Function

    NASA Astrophysics Data System (ADS)

    Grossan, B.; Remillard, R.; Bradt, H.

    1992-12-01

    We carried out a multi-frequency study of a flux-limited (0.95 mu Jy @ 5 keV) sample of 96 emission-line AGN taken from the HEAO-1 LASS/MC survey. Preliminary results of this study were presented at the Jan. 1992 meeting. Here we present new results from line emission and continuum studies and more details regarding the AGN X-ray luminosity functions (XLFs). We find that narrow [OIII] flux correlates well with X-ray flux. This result is consistent with a simple picture where the photoionizing continuum is distributed over a large solid angle in the narrow line region, and is closely related to the X-ray continuum. Broad Balmer lines do not demonstrate a strong correlation with X-ray flux. The UV continuum ( ~ 1400 Angstroms) does not correlate with any optical line emission we measured, but UV variability could have affected this result. In contrast, we find very strong correlations of high-ionization UV broad line fluxes and the simultaneously measured UV continuum. The geometry and/or obscuration effects in the broad line region may therefore be different than those in the narrow line region. A very large spread in the value of broad line Balmer decrements (Hβ /Hα = 0.13 - 0.40) was observed among objects determined to be un-reddened by the lack of an absorption feature at 2175 Angstroms. If there were an intrinsic Balmer decrement for the broad line regions in AGN, the smallest Hβ /Hα values would correspond to extreme values of reddening (E(B-V) > 1 mag). Therefore, we conclude that the broad line Balmer decrement cannot be used in determining continuum reddening in most AGN. We find that the AGN 2-10 keV XLF is roughly a power law, but steepens with increasing luminosity, and turns over below 10(42) erg s(-1) . The XLF of Seyfert 2's resembles a power law from 10(42) - 10(43.5) erg s(-1) , but at higher luminosity, the XLF steepens. In this sample, the cumulative fraction of Seyfert 2's falls rapidly with luminosity, and the overall fraction of Seyfert 2's

  2. Lower-luminosity Galaxies Could Reionize the Universe: Very Steep Faint-end Slopes to the UV Luminosity Functions at z >= 5-8 from the HUDF09 WFC3/IR Observations

    NASA Astrophysics Data System (ADS)

    Bouwens, R. J.; Illingworth, G. D.; Oesch, P. A.; Trenti, M.; Labbé, I.; Franx, M.; Stiavelli, M.; Carollo, C. M.; van Dokkum, P.; Magee, D.

    2012-06-01

    The HUDF09 data are the deepest near-IR observations ever, reaching to 29.5 mag. Luminosity functions (LFs) from these new HUDF09 data for 132 z ~ 7 and z ~ 8 galaxies are combined with new LFs for z ~ 5-6 galaxies and the earlier z ~ 4 LF to reach to very faint limits (<0.05 L* z = 3). The faint-end slopes α are steep: -1.79 ± 0.12 (z ~ 5), -1.73 ± 0.20 (z ~ 6), -2.01 ± 0.21 (z ~ 7), and -1.91 ± 0.32 (z ~ 8). Slopes α <~ -2 lead to formally divergent UV fluxes, though galaxies are not expected to form below ~ - 10 AB mag. These results have important implications for reionization. The weighted mean slope at z ~ 6-8 is -1.87 ± 0.13. For such steep slopes, and a faint-end limit of -10 AB mag, galaxies provide a very large UV ionizing photon flux. While current results show that galaxies can reionize the universe by z ~ 6, matching the Thomson optical depths is more challenging. Extrapolating the current LF evolution to z > 8, taking α to be -1.87 ± 0.13 (the mean value at z ~ 6-8), and adopting typical parameters, we derive Thomson optical depths of 0.061+0.009 - 0.006. However, this result will change if the faint-end slope α is not constant with redshift. We test this hypothesis and find a weak, though uncertain, trend to steeper slopes at earlier times (dα/dz ~ -0.05 ± 0.04) that would increase the Thomson optical depths to 0.079+0.063 - 0.017, consistent with recent WMAP estimates (τ = 0.088 ± 0.015). It may thus not be necessary to resort to extreme assumptions about the escape fraction or clumping factor. Nevertheless, the uncertainties remain large. Deeper WFC3/IR+ACS observations can further constrain the UV ionizing flux from faint galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  3. LOWER-LUMINOSITY GALAXIES COULD REIONIZE THE UNIVERSE: VERY STEEP FAINT-END SLOPES TO THE UV LUMINOSITY FUNCTIONS AT z {>=} 5-8 FROM THE HUDF09 WFC3/IR OBSERVATIONS

    SciTech Connect

    Bouwens, R. J.; Labbe, I.; Franx, M.; Illingworth, G. D.; Oesch, P. A.; Magee, D.; Stiavelli, M.; Carollo, C. M.; Van Dokkum, P.

    2012-06-10

    The HUDF09 data are the deepest near-IR observations ever, reaching to 29.5 mag. Luminosity functions (LFs) from these new HUDF09 data for 132 z {approx} 7 and z {approx} 8 galaxies are combined with new LFs for z {approx} 5-6 galaxies and the earlier z {approx} 4 LF to reach to very faint limits (<0.05 L*{sub z=3}). The faint-end slopes {alpha} are steep: -1.79 {+-} 0.12 (z {approx} 5), -1.73 {+-} 0.20 (z {approx} 6), -2.01 {+-} 0.21 (z {approx} 7), and -1.91 {+-} 0.32 (z {approx} 8). Slopes {alpha} {approx}< -2 lead to formally divergent UV fluxes, though galaxies are not expected to form below {approx} - 10 AB mag. These results have important implications for reionization. The weighted mean slope at z {approx} 6-8 is -1.87 {+-} 0.13. For such steep slopes, and a faint-end limit of -10 AB mag, galaxies provide a very large UV ionizing photon flux. While current results show that galaxies can reionize the universe by z {approx} 6, matching the Thomson optical depths is more challenging. Extrapolating the current LF evolution to z > 8, taking {alpha} to be -1.87 {+-} 0.13 (the mean value at z {approx} 6-8), and adopting typical parameters, we derive Thomson optical depths of 0.061{sup +0.009}{sub -0.006}. However, this result will change if the faint-end slope {alpha} is not constant with redshift. We test this hypothesis and find a weak, though uncertain, trend to steeper slopes at earlier times (d{alpha}/dz {approx} -0.05 {+-} 0.04) that would increase the Thomson optical depths to 0.079{sup +0.063}{sub -0.017}, consistent with recent WMAP estimates ({tau} = 0.088 {+-} 0.015). It may thus not be necessary to resort to extreme assumptions about the escape fraction or clumping factor. Nevertheless, the uncertainties remain large. Deeper WFC3/IR+ACS observations can further constrain the UV ionizing flux from faint galaxies.

  4. Deep Advanced Camera for Surveys Imaging in the Globular Cluster NGC 6397: the Cluster Color-Magnitude Diagram and Luminosity Function

    NASA Astrophysics Data System (ADS)

    Richer, Harvey B.; Dotter, Aaron; Hurley, Jarrod; Anderson, Jay; King, Ivan; Davis, Saul; Fahlman, Gregory G.; Hansen, Brad M. S.; Kalirai, Jason; Paust, Nathaniel; Rich, R. Michael; Shara, Michael M.

    2008-06-01

    We present the color-magnitude diagram (CMD) from deep Hubble Space Telescope imaging in the globular cluster NGC 6397. The Advanced Camera for Surveys (ACS) was used for 126 orbits to image a single field in two colors (F814W, F606W) 5' SE of the cluster center. The field observed overlaps that of archival WFPC2 data from 1994 and 1997 which were used to proper motion (PM) clean the data. Applying the PM corrections produces a remarkably clean CMD which reveals a number of features never seen before in a globular cluster CMD. In our field, the main-sequence stars appeared to terminate close to the location in the CMD of the hydrogen-burning limit predicted by two independent sets of stellar evolution models. The faintest observed main-sequence stars are about a magnitude fainter than the least luminous metal-poor field halo stars known, suggesting that the lowest-luminosity halo stars still await discovery. At the bright end the data extend beyond the main-sequence turnoff to well up the giant branch. A populous white dwarf cooling sequence is also seen in the cluster CMD. The most dramatic features of the cooling sequence are its turn to the blue at faint magnitudes as well as an apparent truncation near F814W = 28. The cluster luminosity and mass functions were derived, stretching from the turnoff down to the hydrogen-burning limit. It was well modeled with either a very flat power-law or a lognormal function. In order to interpret these fits more fully we compared them with similar functions in the cluster core and with a full N-body model of NGC 6397 finding satisfactory agreement between the model predictions and the data. This exercise demonstrates the important role and the effect that dynamics has played in altering the cluster initial mass function.

  5. Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities.

    PubMed

    Schaefer

    2000-04-10

    The galactic environment of gamma-ray bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (1) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (10 with redshifts) shows them to be consistent with a Schechter luminosity function with R*=-21.8+/-1.0, as expected for normal galaxies. (2) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with redshifts; however, the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample (>6x1058 photons s-1 or>1.7x1052 ergs s-1) to be much greater than the average luminosity of the faint sample ( approximately 1058 photons s-1 or approximately 3x1051 ergs s-1). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to gamma-ray burst host galaxies being normal in luminosity.

  6. THE HETDEX PILOT SURVEY. II. THE EVOLUTION OF THE Ly{alpha} ESCAPE FRACTION FROM THE ULTRAVIOLET SLOPE AND LUMINOSITY FUNCTION OF 1.9 < z < 3.8 LAEs

    SciTech Connect

    Blanc, Guillermo A.; Adams, Joshua J.; Gebhardt, Karl; Hao Lei; Fry, Alexander B.; Jeong, Donghui; Komatsu, Eiichiro; Murphy, Jeremy D.; Hill, Gary J.; Drory, Niv; Bender, Ralf; Hopp, Ulrich; Kelzenberg, Ralf; Ciardullo, Robin; Gronwall, Caryl; Schneider, Donald P.; Finkelstein, Steven L.; Gawiser, Eric; MacQueen, Phillip; Roth, Martin M.

    2011-07-20

    We study the escape of Ly{alpha} photons from Ly{alpha} emitting galaxies (LAEs) and the overall galaxy population using a sample of 99 LAEs at 1.9 < z < 3.8 detected through integral-field spectroscopy of blank fields by The Hobby Eberly Telescope Dark Energy Experiment Pilot Survey. For 89 LAEs with broadband counterparts we measure ultraviolet (UV) luminosities and UV slopes, and estimate E(B - V) under the assumption of a constant intrinsic UV slope for LAEs. These quantities are used to estimate dust-corrected star formation rates (SFRs). Comparison between the observed Ly{alpha} luminosity and that predicted by the dust-corrected SFR yields the Ly{alpha} escape fraction. We also measure the Ly{alpha} luminosity function and luminosity density ({rho}{sub Ly{alpha}}) at 2 < z < 4. Using this and other measurements from the literature at 0.3 < z < 7.7 we trace the redshift evolution of {rho}{sub Ly{alpha}.} We compare it to the expectations from the star formation history of the universe and characterize the evolution of the Ly{alpha} escape fraction of galaxies. LAEs at 2 < z < 4 selected down to a luminosity limit of L(Ly{alpha}) > (3-6) x 10{sup 42} erg s{sup -1} (0.25-0.5 L*), have a mean (E(B - V)) = 0.13 {+-} 0.01, implying an attenuation of {approx}70% in the UV. They show a median UV uncorrected SFR = 11 M{sub sun} yr{sup -1}, dust-corrected SFR = 34 M{sub sun} yr{sup -1}, and Ly{alpha} equivalent widths (EWs) which are consistent with normal stellar populations. We measure a median Ly{alpha} escape fraction of 29%, with a large scatter and values ranging from a few percent to 100%. The Ly{alpha} escape fraction in LAEs correlates with E(B - V) in a way that is expected if Ly{alpha} photons suffer from similar amounts of dust extinction as UV continuum photons. This result implies that a strong enhancement of the Ly{alpha} EW with dust, due to a clumpy multi-phase interstellar medium (ISM), is not a common process in LAEs at these redshifts. It also

  7. The HETDEX Pilot Survey. II. The Evolution of the Lyα Escape Fraction from the Ultraviolet Slope and Luminosity Function of 1.9 < z < 3.8 LAEs

    NASA Astrophysics Data System (ADS)

    Blanc, Guillermo A.; Adams, Joshua J.; Gebhardt, Karl; Hill, Gary J.; Drory, Niv; Hao, Lei; Bender, Ralf; Ciardullo, Robin; Finkelstein, Steven L.; Fry, Alexander B.; Gawiser, Eric; Gronwall, Caryl; Hopp, Ulrich; Jeong, Donghui; Kelzenberg, Ralf; Komatsu, Eiichiro; MacQueen, Phillip; Murphy, Jeremy D.; Roth, Martin M.; Schneider, Donald P.; Tufts, Joseph

    2011-07-01

    We study the escape of Lyα photons from Lyα emitting galaxies (LAEs) and the overall galaxy population using a sample of 99 LAEs at 1.9 < z < 3.8 detected through integral-field spectroscopy of blank fields by The Hobby Eberly Telescope Dark Energy Experiment Pilot Survey. For 89 LAEs with broadband counterparts we measure ultraviolet (UV) luminosities and UV slopes, and estimate E(B - V) under the assumption of a constant intrinsic UV slope for LAEs. These quantities are used to estimate dust-corrected star formation rates (SFRs). Comparison between the observed Lyα luminosity and that predicted by the dust-corrected SFR yields the Lyα escape fraction. We also measure the Lyα luminosity function and luminosity density (ρLyα) at 2 < z < 4. Using this and other measurements from the literature at 0.3 < z < 7.7 we trace the redshift evolution of ρLyα. We compare it to the expectations from the star formation history of the universe and characterize the evolution of the Lyα escape fraction of galaxies. LAEs at 2 < z < 4 selected down to a luminosity limit of L(Lyα) > (3-6) × 1042 erg s-1 (0.25-0.5 L*), have a mean langE(B - V)rang = 0.13 ± 0.01, implying an attenuation of ~70% in the UV. They show a median UV uncorrected SFR = 11 M sun yr-1, dust-corrected SFR = 34 M sun yr-1, and Lyα equivalent widths (EWs) which are consistent with normal stellar populations. We measure a median Lyα escape fraction of 29%, with a large scatter and values ranging from a few percent to 100%. The Lyα escape fraction in LAEs correlates with E(B - V) in a way that is expected if Lyα photons suffer from similar amounts of dust extinction as UV continuum photons. This result implies that a strong enhancement of the Lyα EW with dust, due to a clumpy multi-phase interstellar medium (ISM), is not a common process in LAEs at these redshifts. It also suggests that while in other galaxies Lyα can be preferentially quenched by dust due to its scattering nature, this is not the

  8. CONSTRAINING THE EXOZODIACAL LUMINOSITY FUNCTION OF MAIN-SEQUENCE STARS: COMPLETE RESULTS FROM THE KECK NULLER MID-INFRARED SURVEYS

    SciTech Connect

    Mennesson, B.; Serabyn, E.; Colavita, M. M.; Bryden, G.; Doré, O.; Traub, W.; Millan-Gabet, R.; Absil, O.; Wyatt, M.; Danchi, W.; Kuchner, M.; Stapelfeldt, K.; Defrère, D.; Hinz, P.; Ragland, S.; Scott, N.; Woillez, J.

    2014-12-20

    -infrared counterpart points to populations of very hot and small (submicron) grains piling up very close to the sublimation radius. For solar-type stars with no known infrared excess, likely to be the most relevant targets for a future exo-Earth direct imaging mission, we find that their median zodi level is 12 ± 24 zodis and lower than 60 (90) zodis with 95% (99%) confidence, if a lognormal zodi luminosity distribution is assumed.

  9. Constraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared Surveys

    NASA Astrophysics Data System (ADS)

    Mennesson, B.; Millan-Gabet, R.; Serabyn, E.; Colavita, M. M.; Absil, O.; Bryden, G.; Wyatt, M.; Danchi, W.; Defrère, D.; Doré, O.; Hinz, P.; Kuchner, M.; Ragland, S.; Scott, N.; Stapelfeldt, K.; Traub, W.; Woillez, J.

    2014-12-01

    -infrared counterpart points to populations of very hot and small (submicron) grains piling up very close to the sublimation radius. For solar-type stars with no known infrared excess, likely to be the most relevant targets for a future exo-Earth direct imaging mission, we find that their median zodi level is 12 ± 24 zodis and lower than 60 (90) zodis with 95% (99%) confidence, if a lognormal zodi luminosity distribution is assumed.

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

    NASA Astrophysics Data System (ADS)

    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 < 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 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^{+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.

  11. Evidence of a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

    NASA Astrophysics Data System (ADS)

    Castellano, M.; Fontana, A.; Boutsia, K.; Grazian, A.; Pentericci, L.; Bouwens, R.; Dickinson, M.; Giavalisco, M.; Santini, P.; Cristiani, S.; Fiore, F.; Gallozzi, S.; Giallongo, E.; Maiolino, R.; Mannucci, F.; Menci, N.; Moorwood, A.; Nonino, M.; Paris, D.; Renzini, A.; Rosati, P.; Salimbeni, S.; Testa, V.; Vanzella, E.

    2010-02-01

    Aims: We perform a deep search for galaxies in the redshift range 6.5≤ z≤ 7.5, to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their luminosity function. Methods: We present here the first results of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained two Hawk-I pointings on the GOODS South field for a total of ˜32 observing hours, covering ˜90 arcmin^2. The images reach Y=26.7 mag for the two fields. We used public ACS images in the z band to select z-dropout galaxies with the colour criteria Z-Y≥ 1, Y-J<1.5, and Y-K<2. The other public data in the UBVRIJK bands are used to reject possible low redshift interlopers. The output has been compared with extensive Monte Carlo simulations to quantify the observational effects of our selection criteria, as well as the effects of photometric errors. Results: We detect 7 high-quality candidates in the magnitude range Y=25.5-26.7. This interval samples the critical range for M_* at z>6 (M1500≃ -19.5 to -21.5). After accounting for the expected incompleteness, we rule out a luminosity function constant from z=6 to z=7 at a 99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M1500=-19.0, we derive a luminosity density ρ_UV= 1.5+2.0-0.9 × 1025 erg s-1 Hz^{-1 Mpc-3}, implying a decrease by a factor 3.5 from z=6 to z≃ 6.8. On the basis of our findings, we make predictions for the surface densities expected in future surveys, based on ULTRA-VISTA, HST-WFC3, or JWST-NIRCam, evaluating the best observational strategy to maximise their impact.

  12. A complete X-ray sample of the high latitude sky from HEAO-1 A-2: log N lo S and luminosity functions

    NASA Technical Reports Server (NTRS)

    Piccinotti, G.; Mushotzky, R. F.; Boldt, E. A.; Holt, S. S.; Marshall, F. E.; Serlemitsos, P. J.; Shafer, R. A.

    1981-01-01

    An experiment was performed in which a complete X-ray survey of the 8.2 steradians of the sky at galactic latitudes where the absolute value of b is 20 deg down to a limiting sensitivity of 3.1 x ten to the minus 11th power ergs/sq cm sec in the 2-10 keV band. Of the 85 detected sources 17 were identified with galactic objects, 61 were identified with extragalactic objects, and 7 remain unidentified. The log N - log S relation for the non-galactic objects is well fit by the Euclidean relationship. The X-ray spectra of these objects were used to construct log N - log S in physical units. The complete sample of identified sources was used to construct X-ray luminosity functions, using the absolute maximum likelihood method, for clusters galaxies and active galactic nuclei.

  13. THE UV LUMINOSITY FUNCTION OF STAR-FORMING GALAXIES VIA DROPOUT SELECTION AT REDSHIFTS z {approx} 7 AND 8 FROM THE 2012 ULTRA DEEP FIELD CAMPAIGN

    SciTech Connect

    Schenker, Matthew A.; Ellis, Richard S.; Robertson, Brant E.; Schneider, Evan; Ono, Yoshiaki; Ouchi, Masami; Stark, Daniel P.; McLure, Ross J.; Dunlop, James S.; Bowler, Rebecca A. A.; Curtis-Lake, Emma; Rogers, Alexander B.; Cirasuolo, Michele; Koekemoer, Anton; Charlot, Stephane; Furlanetto, Steven R.

    2013-05-10

    We present a catalog of high-redshift star-forming galaxies selected to lie within the redshift range z {approx_equal} 7-8 using the Ultra Deep Field 2012 (UDF12), the deepest near-infrared (near-IR) exposures yet taken with the Hubble Space Telescope (HST). As a result of the increased near-IR exposure time compared to previous HST imaging in this field, we probe {approx}0.65 (0.25) mag fainter in absolute UV magnitude, at z {approx} 7 (8), which increases confidence in a measurement of the faint end slope of the galaxy luminosity function. Through a 0.7 mag deeper limit in the key F105W filter that encompasses or lies just longward of the Lyman break, we also achieve a much-refined color-color selection that balances high redshift completeness and a low expected contamination fraction. We improve the number of dropout-selected UDF sources to 47 at z {approx} 7 and 27 at z {approx} 8. Incorporating brighter archival and ground-based samples, we measure the z {approx_equal} 7 UV luminosity function to an absolute magnitude limit of M{sub UV} = -17 and find a faint end Schechter slope of {alpha}=-1.87{sup +0.18}{sub -0.17}. Using a similar color-color selection at z {approx_equal} 8 that takes our newly added imaging in the F140W filter into account, and incorporating archival data from the HIPPIES and BoRG campaigns, we provide a robust estimate of the faint end slope at z {approx_equal} 8, {alpha}=-1.94{sup +0.21}{sub -0.24}. We briefly discuss our results in the context of earlier work and that derived using the same UDF12 data but with an independent photometric redshift technique.

  14. Run II luminosity progress

    SciTech Connect

    Gollwitzer, K.; /Fermilab

    2007-06-01

    The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. To the collider experiments CDF and D0, over 3 fb{sup -1} of integrated luminosity has been delivered to each. Upgrades and improvements in the Antiproton Source of the production and collection of antiprotons have led to increased number of particles stored in the Recycler. Electron cooling and associated improvements have help make a brighter antiproton beam at collisions. Tevatron improvements to handle the increased number of particles and the beam lifetimes have resulted in an increase in luminosity.

  15. Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to <0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields

    NASA Astrophysics Data System (ADS)

    Illingworth, Garth

    2009-07-01

    The first generations of galaxies were assembled around redshifts z 7-10+, just 500-800 Myr after recombination, in the heart of the reionization of the universe. We know very little about galaxies in this period. Despite great effort with HST and other telescopes, less than 15 galaxies have been reliably detected so far at z>7, contrasting with the 1000 galaxies detected to date at z 6, just 200-400 Myr later, near the end of the reionization epoch. WFC3 IR can dramatically change this situation, enabling derivation of the galaxy luminosity function and its shape at z 7-8 to well below L*, measurement of the UV luminosity density at z 7-8 and z 8-9, and estimates of the contribution of galaxies to reionization at these epochs, as well as characterization of their properties {sizes, structure, colors}. A quantitative leap in our understanding of early galaxies, and the timescales of their buildup, requires a total sample of 100 galaxies at z 7-8 to 29 AB mag. We can achieve this with 192 WFC3 IR orbits on three disjoint fields {minimizing cosmic variance}: the HUDF and the two nearby deep fields of the HUDF05. Our program uses three WFC3 IR filters, and leverages over 600 orbits of existing ACS data, to identify, with low contamination, a large sample of over 100 objects at z 7-8, a very useful sample of 23 at z 8-9, and limits at z 10. By careful placement of the WFC3 IR and parallel ACS pointings, we also enhance the optical ACS imaging on the HUDF and a HUDF05 field. We stress {1} the need to go deep, which is paramount to define L*, the shape, and the slope alpha of the luminosity function {LF} at these high redshifts; and {2} the far superior performance of our strategy, compared with the use of strong lensing clusters, in detecting significant samples of faint z 7-8 galaxies to derive their luminosity function and UV ionizing flux. Our recent z 7.4 NICMOS results show that wide-area IR surveys, even of GOODS-like depth, simply do not reach faint enough at z 7

  16. Ly{alpha} EMITTERS AT z = 7 IN THE SUBARU/XMM-NEWTON DEEP SURVEY FIELD: PHOTOMETRIC CANDIDATES AND LUMINOSITY FUNCTION

    SciTech Connect

    Ota, Kazuaki; Ouchi, Masami; Iye, Masanori; Kashikawa, Nobunari; Kobayashi, Masakazu A. R.; Morokuma, Tomoki; Furusawa, Hisanori; Shimasaku, Kazuhiro; Totani, Tomonori; Nagashima, Masahiro; Harayama, Atsushi; Kodaka, Natsuki; Tajitsu, Akito; Hattori, Takashi

    2010-10-10

    We conducted a deep narrowband NB973 (FWHM = 200 A centered at 9755 A) survey of z = 7 Ly{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 Ly{alpha} at {approx}1 {mu}m than the previous CCDs. Reaching the depth 0.5 mag 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 Ly{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 Ly{alpha} luminosity densities at z = 7 are {approx}7.7%-54% and {approx}5.5%-39%, respectively, of those at z = 5.7, to the Ly{alpha} line luminosity limit of L(Ly{alpha}) {approx}> 9.2 x 10{sup 42} erg s{sup -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. However, even after correcting for this effect of galaxy evolution on the decrease in LAE number density, the z = 7 Ly{alpha} LF still shows a deficit from z = 5.7 LF. This might reflect the attenuation of Ly{alpha} emission by neutral hydrogen remaining at the epoch of reionization and suggests that reionization of the universe might not be complete yet at z = 7. If we attribute the density deficit to reionization, the intergalactic medium transmission for Ly{alpha} photons at z = 7 would be 0.4 {<=} T {sup IGM}{sub Ly{alpha} {<=}} 1, supporting the possible higher neutral fraction at the earlier epochs at z > 6 suggested by the previous surveys of z = 5.7-7 LAEs, z {approx} 6 quasars, and z > 6 gamma-ray bursts.

  17. Lyα Emitters at z = 7 in the Subaru/XMM-Newton Deep Survey Field: Photometric Candidates and Luminosity Functions

    NASA Astrophysics Data System (ADS)

    Ota, Kazuaki; Iye, Masanori; 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

    2010-10-01

    We conducted a deep narrowband NB973 (FWHM = 200 Å centered at 9755 Å) survey of z = 7 Lyα 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 Lyα at ~1 μm than the previous CCDs. Reaching the depth 0.5 mag 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 Lyα 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 Lyα luminosity densities at z = 7 are ~7.7%-54% and ~5.5%-39%, respectively, of those at z = 5.7, to the Lyα line luminosity limit of L(Lyα) >~ 9.2 × 1042 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. However, even after correcting for this effect of galaxy evolution on the decrease in LAE number density, the z = 7 Lyα LF still shows a deficit from z = 5.7 LF. This might reflect the attenuation of Lyα emission by neutral hydrogen remaining at the epoch of reionization and suggests that reionization of the universe might not be complete yet at z = 7. If we attribute the density deficit to reionization, the intergalactic medium transmission for Lyα photons at z = 7 would be 0.4 <= T IGM Lyα <= 1, supporting the possible higher neutral fraction at the earlier epochs at z > 6 suggested by the previous surveys of z = 5.7-7 LAEs, z ~ 6 quasars, and z > 6 gamma-ray bursts. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  18. Psychometric function of jittered rate pitch discrimination.

    PubMed

    Bahmer, Andreas; Baumann, Uwe

    2014-07-01

    The impact of jitter on rate pitch discrimination (JRPD) is still a matter of debate. Previous studies have used adaptive procedures to assess pitch discrimination abilities of jittered rate pulses (Dobie and Dillier, 1985; Chen et al., 2005) or have used jitter detection thresholds (Fearn, 2001). Previous studies were conducted in a relatively small number of subjects using either a single-electrode cochlear implant (Dobie and Dillier, 1985, n = 2) or the Nucleus multi-channel devices (Fearn, 2001, n = 3; Chen et al., 2005, n = 5). The successful application of an adaptive procedure requires a monotone psychometric function to achieve asymptotic results. The underlying psychometric function of rate jitter has not been investigated so far. In order to close this knowledge gap, the present study determines psychometric functions by measuring of JRPD with a fixed stimulus paradigm. A rather large range of temporal, Gaussian distributed jitter standard deviation 0, 1, 2, 3, 4 ms was applied to electrical pulse patterns. Since the shape of the underlying probability density function (PDF) may also effect JRPD, a uniform PDF was alternatively applied. 7 CI users (8 ears, high-level performers with open-speech perception, MED-EL Pulsar/Sonata devices, Innsbruck, Austria) served as subjects for the experiment. JRPD was assessed with a two-stage forced choice procedure. Gross results showed decreasing JRPD with increasing amounts of jitter independent of the applied jitter distribution. In conclusion, pulse rate jitter affects JRPD and therefore should be considered in current coding strategies. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. The evolution of the rest-frame J- and H-band luminosity function of galaxies to z=3.5

    NASA Astrophysics Data System (ADS)

    Stefanon, Mauro; Marchesini, Danilo

    2013-02-01

    We present the rest-frame J- and H-band luminosity function (LF) of field galaxies, based on a deep multiwavelength composite sample from the Multiwavelength Survey by Yale-Chile, Faint Infrared Extragalactic Survey and GOODS Chandra Deep Field-South survey public catalogues, covering a total area of 450 arcmin2. The availability of flux measurements in the Spitzer Infrared Array Camera 3.6, 4.5, 5.8 and 8 μm channels allows us to compute absolute magnitudes in the rest-frame J and H bands up to z = 3.5 minimizing the dependence on the stellar evolution models. We compute the LF in the four redshift bins: 1.5 < z < 2.0; 2.0 < z < 2.5; 2.5 < z < 3.0 and 3.0 < z < 3.5. Combining our results with those already available at lower redshifts, we find that (1) the faint-end slope is consistent with being constant up to z = 3.5, with α = -1.05 ± 0.03 for the rest-frame J band and α = -1.15 ± 0.02 for the rest-frame H band; (2) the normalization φ* decreases by a factor of 4-6 between z = 0 and z ≃ 1.75 and by a factor of 2-3 between z ≃ 1.75 and z = 3.25; (3) the characteristic magnitude M* shows a brightening from z = 0 to z ≃ 2 followed by a slow dimming to z = 3.25. We finally compute the luminosity density (LD) in both rest-frame J and H bands. The analysis of our results together with those available in the literature shows that the LD is approximately constant up to z ≈ 1, and it then decreases by a factor of 6 up to z = 3.5.

  20. SDC at high luminosity

    SciTech Connect

    Green, D.

    1990-05-01

    Why is it prudent to plan for a luminosity (L) of >10{sup 34}/(cm{sup 2}sec) from the beginning First, the SSC is easily capable of attaining high luminosity. In comparison, for {bar p}p machines such as the Tevatron, increases in L are difficult. Second, after early runs at design luminosity, the only simple upgrade to a general purpose detector is an increase in luminosity. Third, and most important, the only known model independent physics goal of SSC is in the electroweak sector; the ZZ scattering amplitude reaches the unitarity bound for {radical}{cflx s} {approx equal} 3 TeV. In order to reach this mass range, and assure that some new physics is found, high luminosity running is needed. Since high luminosity running is desirable and easily attainable, it is inevitable. Therefore, one should build the hooks'' for upgrades to high L into the SDC from the beginning. The experience of CDF is that if this is not done, upgrades can be painful. Specifically, if possible, SDC should make sure that the chosen technologies allow high L operation. The time to plan for the whole useful lifetime of SDC is from the beginning. 9 refs., 6 figs.

  1. The ALHAMBRA survey: B-band luminosity function of quiescent and star-forming galaxies at 0.2 ≤ z < 1 by PDF analysis

    NASA Astrophysics Data System (ADS)

    López-Sanjuan, C.; Tempel, E.; Benítez, N.; Molino, A.; Viironen, K.; Díaz-García, L. A.; Fernández-Soto, A.; Santos, W. A.; Varela, J.; Cenarro, A. J.; Moles, M.; Arnalte-Mur, P.; Ascaso, B.; Montero-Dorta, A. D.; Pović, M.; Martínez, V. J.; Nieves-Seoane, L.; Stefanon, M.; Hurtado-Gil, Ll.; Márquez, I.; Perea, J.; Aguerri, J. A. L.; Alfaro, E.; Aparicio-Villegas, T.; Broadhurst, T.; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; González Delgado, R. M.; Husillos, C.; Infante, L.; Masegosa, J.; del Olmo, A.; Prada, F.; Quintana, J. M.

    2017-03-01

    Aims: Our goal is to study the evolution of the B-band luminosity function (LF) since z 1 using ALHAMBRA data. Methods: We used the photometric redshift and the I-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I ≤ 24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift - magnitude - galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also included in our analysis. Results: We modelled the LF with a redshift-dependent Schechter function affected by the same selection effects than the data. The measured ALHAMBRA LF at 0.2 ≤ z< 1 and the evolving Schechter parameters both for quiescent and star-forming galaxies agree with previous results in the literature. The estimated redshift evolution of MB* ∝ Qz is QSF = -1.03 ± 0.08 and QQ = -0.80 ± 0.08, and of log 10φ∗ ∝ Pz is PSF = -0.01 ± 0.03 and PQ = -0.41 ± 0.05. The measured faint-end slopes are αSF = -1.29 ± 0.02 and αQ = -0.53 ± 0.04. We find a significant population of faint quiescent galaxies with MB ≳ -18, modelled by a second Schechter function with slope β = -1.31 ± 0.11. Conclusions: We present a robust methodology to compute LFs using multi-filter photometric data. The application to ALHAMBRA shows a factor 2.55 ± 0.14 decrease in the luminosity density jB of star-forming galaxies, and a factor 1.25 ± 0.16 increase in the jB of quiescent ones since z = 1, confirming the continuous build-up of the quiescent population with cosmic time. The contribution of the faint quiescent population to jB increases from 3% at z = 1 to 6% at z = 0. The developed methodology will be applied to future multi-filter surveys such as J-PAS. Based on observations

  2. Bayesian inferences of galaxy formation from the K-band luminosity and H I mass functions of galaxies: constraining star formation and feedback

    NASA Astrophysics Data System (ADS)

    Lu, Yu; Mo, H. J.; Lu, Zhankui; Katz, Neal; Weinberg, Martin D.

    2014-09-01

    We infer mechanisms of galaxy formation for a broad family of semi-analytic models (SAMs) constrained by the K-band luminosity function and H I mass function of local galaxies using tools of Bayesian analysis. Even with a broad search in parameter space the whole model family fails to match to constraining data. In the best-fitting models, the star formation and feedback parameters in low-mass haloes are tightly constrained by the two data sets, and the analysis reveals several generic failures of models that similarly apply to other existing SAMs. First, based on the assumption that baryon accretion follows the dark matter accretion, large mass-loading factors are required for haloes with circular velocities lower than 200 km s-1, and most of the wind mass must be expelled from the haloes. Second, assuming that the feedback is powered by Type II supernovae with a Chabrier initial mass function, the outflow requires more than 25 per cent of the available supernova kinetic energy. Finally, the posterior predictive distributions for the star formation history are dramatically inconsistent with observations for masses similar to or smaller than the Milky Way mass. The inferences suggest that the current model family is still missing some key physical processes that regulate the gas accretion and star formation in galaxies with masses below that of the Milky Way.

  3. Evolution of the H β + [O III] and [O II] luminosity functions and the [O II] star formation history of the Universe up to z ˜ 5 from HiZELS

    NASA Astrophysics Data System (ADS)

    Khostovan, A. A.; Sobral, D.; Mobasher, B.; Best, P. N.; Smail, I.; Stott, J. P.; Hemmati, S.; Nayyeri, H.

    2015-10-01

    We investigate the evolution of the H β + [O III] and [O II] luminosity functions from z ˜ 0.8 to ˜5 in four redshift slices per emission line using data from the High-z Emission Line Survey (HiZELS). This is the first time that the H β + [O III] and [O II] luminosity functions have been studied at these redshifts in a self-consistent analysis. This is also the largest sample of [O II] and H β + [O III] emitters (3475 and 3298 emitters, respectively) in this redshift range, with large comoving volumes ˜1 × 106 Mpc-3 in two independent volumes (COSMOS and UDS), greatly reducing the effects of cosmic variance. The emitters were selected by a combination of photometric redshift and colour-colour selections, as well as spectroscopic follow-up, including recent spectroscopic observations using DEIMOS and MOSFIRE on the Keck Telescopes and FMOS on Subaru. We find a strong increase in L⋆ and a decrease in φ⋆ for both H β + [O III] and [O II] emitters. We derive the [O II] star formation history of the Universe since z ˜ 5 and find that the cosmic star formation rate density (SFRD) rises from z ˜ 5 to ˜3 and then drops towards z ˜ 0. We also find that our star formation history is able to reproduce the evolution of the stellar mass density up to z ˜ 5 based only on a single tracer of star formation. When comparing the H β + [O III] SFRDs to the [O II] and H α SFRD measurements in the literature, we find that there is a remarkable agreement, suggesting that the H β + [O III] sample is dominated by star-forming galaxies at high-z rather than AGNs.

  4. A complete X-ray sample of the high-latitude /absolute value of b greater than 20 deg/ sky from HEAO 1 A-2 - Log N-log S and luminosity functions

    NASA Technical Reports Server (NTRS)

    Piccinotti, G.; Mushotzky, R. F.; Boldt, E. A.; Holt, S. S.; Marshall, F. E.; Serlemitsos, P. J.; Shafer, R. A.

    1982-01-01

    An all-sky survey of X-ray sources was performed, complete to a limiting sensitivity of 3.1 x 10 to the -11 ergs/sq cm/s in the 2-10 keV band. The complete sample has allowed construction of luminosity functions based on a flux-limited sample for clusters of galaxies and active galactic nuclei. Integration of the best-fit luminosity functions indicates that clusters of galaxies contribute about 4% of the 2-10 keV DXRB, and active galactic nuclei about 20%. It is predicted that many of the objects seen in the deep survey should be local, relatively low luminosity active galactic nuclei and clusters of galaxies.

  5. Effect of primordial non-Gaussianities on the far-UV luminosity function of high-redshift galaxies: implications for cosmic reionization

    NASA Astrophysics Data System (ADS)

    Chevallard, Jacopo; Silk, Joseph; Nishimichi, Takahiro; Habouzit, Melanie; Mamon, Gary A.; Peirani, Sébastien

    2015-01-01

    Understanding how the intergalactic medium (IGM) was reionized at z ≳ 6 is one of the big challenges of current high-redshift astronomy. It requires modelling the collapse of the first astrophysical objects (Pop III stars, first galaxies) and their interaction with the IGM, while at the same time pushing current observational facilities to their limits. The observational and theoretical progress of the last few years have led to the emergence of a coherent picture in which the budget of hydrogen-ionizing photons is dominated by low-mass star-forming galaxies, with little contribution from Pop III stars and quasars. The reionization history of the Universe therefore critically depends on the number density of low-mass galaxies at high redshift. In this work, we explore how changes in the cosmological model, and in particular in the statistical properties of initial density fluctuations, affect the formation of early galaxies. Following Habouzit et al. (2014), we run five different N-body simulations with Gaussian and (scale-dependent) non-Gaussian initial conditions, all consistent with Planck constraints. By appealing to a phenomenological galaxy formation model and to a population synthesis code, we compute the far-UV galaxy luminosity function down to MFUV = -14 at redshift 7 ≤ z ≤ 15. We find that models with strong primordial non-Gaussianities on ≲ Mpc scales show a far-UV luminosity function significantly enhanced (up to a factor of 3 at z = 14) in low-mass galaxies. We adopt a reionization model calibrated from state-of-the-art hydrodynamical simulations and show that such scale-dependent non-Gaussianities leave a clear imprint on the Universe reionization history and electron Thomson scattering optical depth τe. Although current uncertainties in the physics of reionization and on the determination of τe still dominate the signatures of non-Gaussianities, our results suggest that τe could ultimately be used to constrain the statistical properties

  6. Constraints of the Luminosities of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hakkila, J.; Meegan, C.; Horack, J.; Pendleton, G.; Briggs, M.; Paciesas, W.; Emslie, G.; Mallozzi, R.

    1995-09-01

    Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with Ω = 1 and Λ = 0, then very few luminosity constraints exist.

  7. RHIC LUMINOSITY UPGRADE PROGRAM

    SciTech Connect

    Fischer, W.

    2010-05-23

    The Relativistic Heavy Ion Collider (RHIC) operates with either ions or polarized protons. After increasing the heavy ion luminosity by two orders of magnitude since its commissioning in 2000, the current luminosity upgrade program aims for an increase by another factor of 4 by means of 3D stochastic cooling and a new 56 MHz SRF system. An Electron Beam Ion Source is being commissioned that will allow the use of uranium beams. Electron cooling is considered for collider operation below the current injection energy. For the polarized proton operation both luminosity and polarization are important. In addition to ongoing improvements in the AGS injector, the construction of a new high-intensity polarized source has started. In RHIC a number of upgrades are under way to increase the intensity and polarization transmission to 250 GeV beam energy. Electron lenses will be installed to partially compensate the head-on beam-beam effect.

  8. Luminosity enhancements at SLAC

    SciTech Connect

    Coward, D.H.

    1984-04-01

    Several ideas are discussed that have been proposed to improve the luminosity at the SPEAR and PEP electron-positron storage rings and to insure good luminosity at the SLAC Linear Collider. There have been two proposals studied recently for SPEAR: a Microbeta insertion using Sa