Browsing by Subject "LUMINOSITY FUNCTION"

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  • Strazzullo, V.; Coogan, R. T.; Daddi, E.; Sargent, M. T.; Gobat, R.; Valentino, F.; Bethermin, M.; Pannella, M.; Dickinson, M.; Renzini, A.; Arimoto, N.; Cimatti, A.; Dannerbauer, H.; Finoguenov, A.; Liu, D.; Onodera, M. (2018)
    We present Atacama Large Millimeter/submillimeter Array observations of the 870 mu m continuum and CO(4-3) line emission in the core of the galaxy cluster Cl J1449+0856 at z = 2, a near-IR-selected, X-ray-detected system in the mass range of typical progenitors of today's massive clusters. The 870 mu m map reveals six F-870 mu m > 0.5 mJy sources spread over an area of 0.07 arcmin(2), giving an overdensity of a factor of similar to 10 (6) with respect to blank-field counts down to F-870 mu m > 1 mJy (> 0.5 mJy). On the other hand, deep CO(4-3) follow-up confirms membership of three of these sources but suggests that the remaining three, including the brightest 870 mu m sources in the field (F-870 mu m greater than or similar to 2 mJy), are likely interlopers. The measurement of 870 mu m continuum and CO(4-3) line fluxes at the positions of previously known cluster members provides a deep probe of dusty star formation occurring in the core of this high-redshift structure, adding up to a total star formation rate of similar to 700 +/- 100 M-circle dot yr(-1) and yielding an integrated star formation rate density of similar to 10(4) M-circle dot yr(-1) Mpc(-3), five orders of magnitude larger than in the field at the same epoch, due to the concentration of star-forming galaxies in the small volume of the dense cluster core. The combination of these observations with previously available Hubble Space Telescope imaging highlights the presence in this same volume of a population of galaxies with already suppressed star formation. This diverse composition of galaxy populations in Cl J1449+0856 is especially highlighted at the very cluster center, where a complex assembly of quiescent and star-forming sources is likely forming the future brightest cluster galaxy.
  • CORE Collaboration; De Zotti, G.; Kiiveri, K.; Kurki-Suonio, H.; Lindholm, V.; Väliviita, J. (2018)
    We discuss the potential of a next generation space-borne Cosmic Microwave Background (CMB) experiment for studies of extragalactic sources. Our analysis has particular bearing on the definition of the future space project, CORE, that has been submitted in response to ESA's call for a Medium-size mission opportunity as the successor of the Planck satellite. Even though the effective telescope size will be somewhat smaller than that of Planck, CORE will have a considerably better angular resolution at its highest frequencies, since, in contrast with Planck, it will be diffraction limited at all frequencies. The improved resolution implies a considerable decrease of the source confusion, i.e. substantially fainter detection limits. In particular, CORE will detect thousands of strongly lensed high-z galaxies distributed over the full sky. The extreme brightness of these galaxies will make it possible to study them, via follow-up observations, in extraordinary detail. Also, the CORE resolution matches the typical sizes of high-z galaxy proto-clusters much better than the Planck resolution, resulting in a much higher detection efficiency; these objects will be caught in an evolutionary phase beyond the reach of surveys in other wavebands. Furthermore, CORE will provide unique information on the evolution of the star formation in virialized groups and clusters of galaxies up to the highest possible redshifts. Finally, thanks to its very high sensitivity, CORE will detect the polarized emission of thousands of radio sources and, for the first time, of dusty galaxies, at mm and sub-mm wavelengths, respectively.
  • Vardoulaki, E.; Jimenez Andrade, E. F.; Delvecchio, I.; Zagreb, University; Schinnerer, E.; Sargent, M. T.; Gozaliasl, G.; Finoguenov, A.; Bondi, M.; Zamorani, G.; Badescu, T.; Leslie, S. K.; Ceraj, L.; Tisanic, K.; Karim, A.; Magnelli, B.; Bertoldi, F.; Romano-Diaz, E.; Harrington, K. (2021)
    Context. Radio active galactic nuclei (AGN) are traditionally separated into two Fanaroff-Riley (FR) type classes, edge-brightened FRII sources or edge-darkened FRI sources. With the discovery of a plethora of radio AGN of different radio shapes, this dichotomy is becoming too simplistic in linking the radio structure to the physical properties of radio AGN, their hosts, and their environment.Aims. We probe the physical properties and large-scale environment of radio AGN in the faintest FR population to date, and link them to their radio structure. We use the VLA-COSMOS Large Project at 3 GHz (3 GHz VLA-COSMOS), with a resolution and sensitivity of 75 0 75 and 2.3 mu Jy beam(-1) to explore the FR dichotomy down to mu Jy levels.Methods. We classified objects as FRIs, FRIIs, or hybrid FRI/FRII based on the surface-brightness distribution along their radio structure. Our control sample was the jet-less/compact radio AGN objects (COM AGN), which show excess radio emission at 3 GHz VLA-COSMOS exceeding what is coming from star-formation alone; this sample excludes FRs. The largest angular projected sizes of FR objects were measured by a machine-learning algorithm and also by hand, following a parametric approach to the FR classification. Eddington ratios were calculated using scaling relations from the X-rays, and we included the jet power by using radio luminosity as a probe. Furthermore, we investigated their host properties (star-formation ratio, stellar mass, morphology), and we explore their incidence within X-ray galaxy groups in COSMOS, and in the density fields and cosmic-web probes in COSMOS.Results. Our sample is composed of 59 FRIIs, 32 FRI/FRIIs, 39 FRIs, and 1818 COM AGN at 0.03 (238.2)(36.9) 36.9 238.2 kpc, larger than that of FRI/FRIIs and FRIs by a factor of 2-3. The COM AGN have sizes smaller than 30 kpc, with a median value of 1.7 (4.7)(1.5) 1.5 4.7 kpc. The median Eddington ratio of FRIIs is 0.006 (0.007)(0.005) 0.005 0.007 , a factor of 2.5 less than in FRIs and a factor of 2 higher than in FRI/FRII. When the jet power is included, the median Eddington ratios of FRII and FRI/FRII increase by a factor of 12 and 15, respectively. FRs reside in their majority in massive quenched hosts (M-*>10(10.5) M-circle dot), with older episodes of star-formation linked to lower X-ray galaxy group temperatures, suggesting radio-mode AGN quenching. Regardless of their radio structure, FRs and COM AGN are found in all types and density environments (group or cluster, filaments, field).Conclusions. By relating the radio structure to radio luminosity, size, Eddington ratio, and large-scale environment, we find a broad distribution and overlap of FR and COM AGN populations. We discuss the need for a different classification scheme, that expands the classic FR classification by taking into consideration the physical properties of the objects rather than their projected radio structure which is frequency-, sensitivity- and resolution-dependent. This point is crucial in the advent of current and future all-sky radio surveys.
  • Mulroy, Sarah L.; Farahi, Arya; Evrard, August E.; Smith, Graham P.; Finoguenov, Alexis; O'Donnell, Christine; Marrone, Daniel P.; Abdulla, Zubair; Bourdin, Herve; Carlstrom, John E.; Democles, Jessica; Haines, Chris P.; Martino, Rossella; Mazzotta, Pasquale; McGee, Sean L.; Okabe, Nobuhiro (2019)
    We present a simultaneous analysis of galaxy cluster scaling relations between weak-lensing mass and multiple cluster observables, across a wide range of wavelengths, that probe both gas and stellar content. Our new hierarchical Bayesian model simultaneously considers the selection variable alongside all other observables in order to explicitly model intrinsic property covariance and account for selection effects. We apply this method to a sample of 41 clusters at 0.15 <z <0.30, with a well-defined selection criteria based on RASS X-ray luminosity, and observations from Chandra/XMM, SZA, Planck, UKIRT, SUSS, and Subaru. These clusters have well-constrained weak-lensing mass measurements based on Subaru/SuprimeCam observations, which serve as the reference masses in our model. We present 30 scaling relation parameters for 10 properties. All relations probing the intracluster gas are slightly shallower than self-similar predictions, in moderate tension with prior measurements, and the stellar fraction decreases with mass. K-band luminosity has the lowest intrinsic scatter with a 95th percentile of 0.16, while the lowest scatter gas probe is gas mass with a fractional intrinsic scatter of 0.16 +/- 0.03. We find no distinction between the core-excised X-ray or high-resolution Sunyaev-Zel'dovich relations of clusters of different central entropy, but find with modest significance that higher entropy clusters have higher stellar fractions than their lower entropy counterparts. We also report posterior mass estimates from our likelihood model.
  • Capasso, R.; Mohr, J. J.; Saro, A.; Biviano, A.; Clerc, N.; Finoguenov, A.; Grandis, S.; Collins, C.; Erfanianfar, G.; Damsted, S.; Kirkpatrick, C.; Kukkola, A. (2019)
    We use galaxy dynamical information to calibrate the richness-mass scaling relation of a sample of 428 galaxy clusters that are members of the CODEX sample with redshifts up to z similar to 0.7. These clusters were X-ray selected using the ROSAT All-Sky Survey (RASS) and then cross-matched to associated systems in the redMaPPer (the red sequence Matched-filter Probabilistic Percolation) catalogue from the Sloan Digital Sky Survey. The spectroscopic sample we analyse was obtained in the SPIDERS program and contains similar to 7800 red member galaxies. Adopting NFW mass and galaxy density profiles and a broad range of orbital anisotropy profiles, we use the Jeans equation to calculate halo masses. Modelling the scaling relation as lambda proportional to A(lambda) M-200c(B lambda) (1 + z)()lambda), we find the parameter constraints A(lambda) = 38.6(-4.1)(+3.1) +/- 3.9, B-lambda = 0.99(-0.07)(+0.06) +/- 0.04, and gamma(lambda) = -1.13(-0.34)(+0.32) +/- 0.49, where we present systematic uncertainties as a second component. We find good agreement with previously published mass trends with the exception of those from stacked weak lensing analyses. We note that although the lensing analyses failed to account for the Eddington bias, this is not enough to explain the differences. We suggest that differences in the levels of contamination between pure redMaPPer and RASS + redMaPPer samples could well contribute to these differences. The redshift trend we measure is more negative than but statistically consistent with previous results. We suggest that our measured redshift trend reflects a change in the cluster galaxy red sequence (RS) fraction with redshift, noting that the trend we measure is consistent with but somewhat stronger than an independently measured redshift trend in the RS fraction. We also examine the impact of a plausible model of correlated scatter in X-ray luminosity and optical richness, showing it has negligible impact on our results.
  • Aghanim, N.; Keihänen, Elina; Kurki-Suonio, H.; Valiviita, J.; Planck Collaboration (2015)
    We have used the Planck all-sky submillimetre and millimetre maps to search for rare sources distinguished by extreme brightness, a few hundred millijanskies, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High Frequency Instrument (HFI) directly from the maps and from the Planck Catalogue of Compact Sources (PCCS), all satisfy the criterion of having their rest-frame far-infrared peak redshifted to the frequency range 353-857 GHz. This colour-selection favours galaxies in the redshift range z = 2-4, which we consider as cold peaks in the cosmic infrared background. With a 4.'5 beam at the four highest frequencies, our sample is expected to include overdensities of galaxies in groups or clusters, lensed galaxies, and chance line-of-sight projections. We perform a dedicated Herschel-SPIRE follow-up of 234 such Planck targets, finding a significant excess of red 350 and 500 mu m sources, in comparison to reference SPIRE fields. About 94% of the SPIRE sources in the Planck fields are consistent with being overdensities of galaxies peaking at 350 mu m, with 3% peaking at 500 mu m, and none peaking at 250 mu m. About 3% are candidate lensed systems, all 12 of which have secure spectroscopic confirmations, placing them at redshifts z > 2.2. Only four targets are Galactic cirrus, yielding a success rate in our search strategy for identifying extragalactic sources within the Planck beam of better than 98%. The galaxy overdensities are detected with high significance, half of the sample showing statistical significance above 10 sigma. The SPIRE photometric redshifts of galaxies in overdensities suggest a peak at z similar or equal to 2, assuming a single common dust temperature for the sources of T-d = 35 K. Under this assumption, we derive an infrared (IR) luminosity for each SPIRE source of about 4x10(12) L-circle dot, yielding star formation rates of typically 700 M-circle dot yr(-1). If the observed overdensities are actual gravitationally-bound structures, the total IR luminosity of all their SPIRE-detected sources peaks at 4 x 10(13) L-circle dot, leading to total star formation rates of perhaps 7 x 10(3) M-circle dot yr(-1) per overdensity. Taken together, these sources show the signatures of high-z (z > 2) protoclusters of intensively star-forming galaxies. All these observations confirm the uniqueness of our sample compared to reference samples and demonstrate the ability of the all-sky Planck-HFI cold sources to select populations of cosmological and astrophysical interest for structure formation studies.
  • Clerc, N.; Merloni, A.; Zhang, Y. -Y.; Finoguenov, A.; Dwelly, T.; Nandra, K.; Collins, C.; Dawson, K.; Kneib, J. -P.; Rozo, E.; Rykoff, E.; Sadibekova, T.; Brownstein, J.; Lin, Y. -T.; Ridl, J.; Salvato, M.; Schwope, A.; Steinmetz, M.; Seo, H. -J.; Tinker, J. (2016)
    SPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a programme dedicated to the homogeneous and complete spectroscopic follow-up of X-ray active galactic nuclei and galaxy clusters over a large area (similar to 7500 deg(2)) of the extragalactic sky. SPIDERS is part of the Sloan Digital Sky Survey (SDSS)-IV project, together with the Extended Baryon Oscillation Spectroscopic Survey and the Time-Domain Spectroscopic Survey. This paper describes the largest project within SPIDERS before the launch of eROSITA: an optical spectroscopic survey of X-ray-selected, massive (similar to 10(14)-10(15) M-circle dot) galaxy clusters discovered in ROSAT and XMM-Newton imaging. The immediate aim is to determine precise (Delta(z) similar to 0.001) redshifts for 4000-5000 of these systems out to z similar to 0.6. The scientific goal of the program is precision cosmology, using clusters as probes of large-scale structure in the expanding Universe. We present the cluster samples, target selection algorithms and observation strategies. We demonstrate the efficiency of selecting targets using a combination of SDSS imaging data, a robust red-sequence finder and a dedicated prioritization scheme. We describe a set of algorithms and work-flow developed to collate spectra and assign cluster membership, and to deliver catalogues of spectroscopically confirmed clusters. We discuss the relevance of line-of-sight velocity dispersion estimators for the richer systems. We illustrate our techniques by constructing a catalogue of 230 spectroscopically validated clusters (0.031 <z <0.658), found in pilot observations. We discuss two potential science applications of the SPIDERS sample: the study of the X-ray luminosity-velocity dispersion (L-X-sigma) relation and the building of stacked phase-space diagrams.
  • McNab, Karen; Balogh, Michael L.; van der Burg, Remco F. J.; Forestell, Anya; Webb, Kristi; Vulcani, Benedetta; Rudnick, Gregory; Muzzin, Adam; Cooper, M. C.; McGee, Sean; Biviano, Andrea; Cerulo, Pierluigi; Chan, Jeffrey C. C.; De Lucia, Gabriella; Demarco, Ricardo; Finoguenov, Alexis; Forrest, Ben; Golledge, Caelan; Jablonka, Pascale; Lidman, Chris; Nantais, Julie; Old, Lyndsay; Pintos-Castro, Irene; Poggianti, Bianca; Reeves, Andrew M. M.; Wilson, Gillian; Yee, Howard K. C.; Zaritsky, Dennis (2021)
    We measure the rate of environmentally driven star formation quenching in galaxies at z similar to 1, using eleven massive () galaxy clusters spanning a redshift range 1.0 < z < 1.4 from the GOGREEN sample. We identify three different types of transition galaxies: 'green valley' (GV) galaxies identified from their rest-frame (NUV - V) and (V - J) colours; 'blue quiescent' (BQ) galaxies, found at the blue end of the quiescent sequence in (U - V) and (V - J) colour; and spectroscopic post-starburst (PSB) galaxies. We measure the abundance of these galaxies as a function of stellar mass and environment. For high-stellar mass galaxies (logM/M-circle dot > 10.5) we do not find any significant excess of transition galaxies in clusters, relative to a comparison field sample at the same redshift. It is likely that such galaxies were quenched prior to their accretion in the cluster, in group, filament, or protocluster environments. For lower stellar mass galaxies (9.5 < logM/M-circle dot < 10.5) there is a small but significant excess of transition galaxies in clusters, accounting for an additional similar to 5-10 percent of the population compared with the field. We show that our data are consistent with a scenario in which 20-30 percent of low-mass, star-forming galaxies in clusters are environmentally quenched every Gyr, and that this rate slowly declines from z = 1 to z = 0. While environmental quenching of these galaxies may include a long delay time during which star formation declines slowly, in most cases this must end with a rapid (tau < 1Gyr) decline in star formation rate.
  • McAlpine, Stuart; Smail, Ian; Bower, Richard G.; Swinbank, A. M.; Trayford, James W.; Theuns, Tom; Baes, Maarten; Camps, Peter; Crain, Robert A.; Schaye, Joop (2019)
    We exploit EAGLE, a cosmological hydrodynamical simulation, to reproduce the selection of the observed submillimetre (submm) galaxy population by selecting the model galaxies at z >= 1 with mock submm fluxes S-850 mu m >= 1mJy. We find a reasonable agreement between the model galaxies within this sample and the properties of the observed submm population, such as their star formation rates (SFRs) at z <3, redshift distribution, and many integrated galaxy properties. We find that the median redshift of the S-850 (mu m) >= 1mJy model population is z approximate to 2.5, and that they are massive galaxies (M-* similar to 10(11)M(circle dot)) with high dust masses (M-dust similar to 10(8)M(circle dot)), gas fractions (f(gas) approximate to 50 per cent), and SFRs ((*) approximate to 100 M-circle dot yr(-1)). In addition, we find that they have major and minor merger fractions similar to the general population, suggesting that mergers are not the sole driver of the high SFRs in the model submm galaxies. Instead, the S-850 (mu m) >= 1mJy model galaxies yield high SFRs primarily because they maintain a significant gas reservoir as a result of hosting an undermassive black hole relative to comparably massive galaxies. Not all 'highly star-forming' ((*) >= 80M(circle dot) yr(-1)) EAGLE galaxies have submm fluxes S-850 (mu m) >= 1 mJy. We investigate the nature of these highly star-forming 'Submm-Faint' galaxies (i.e. (*) = 80 M-circle dot yr(-1) but S-850 (mu m) <1mJy) and find that they are similar to the model submm galaxies, being gas rich and hosting undermassive black holes. However, they are also typically at higher redshifts (z > 4) and are lower mass (M-* similar to 10(10) M-circle dot). These typically higher redshift galaxies show stronger evidence for having been triggered by major mergers, and critically, they are likely missed by most current submm surveys due to their higher dust temperatures and lower dust masses.
  • Amati, L.; O’Brien, P.; Götz, D.; Bozzo, E.; Tenzer, C.; Frontera, F.; Ghirlanda, G.; Labanti, C.; Osborne, J.P.; Stratta, G.; Tanvir, N.; Willingale, R.; Attina, P.; Campana, R.; Castro-Tirado, A.J.; Contini, C.; Fuschino, F.; Gomboc, A.; Hudec, R.; Orleanski, P.; Renotte, E.; Rodic, T.; Bagoly, Z.; Blain, A.; Callanan, P.; Covino, S.; Ferrara, A.; Le Floch, E.; Marisaldi, M.; Mereghetti, S.; Rosati, P.; Vacchi, A.; D’Avanzo, P.; Giommi, P.; Piranomonte, S.; Piro, L.; Reglero, V.; Rossi, A.; Santangelo, A.; Salvaterra, R.; Tagliaferri, G.; Vergani, S.; Vinciguerra, S.; Briggs, M.; Campolongo, E.; Ciolfi, R.; Connaughton, V.; Cordier, B.; Morelli, B.; Korpela, S. (2018)
    Abstract THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5-1 arcmin localization, an energy band extending from several MeV down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift ∼ 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ’20s / early ’30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).
  • Miniati, Francesco; Finoguenov, Alexis; Silverman, John D.; Carollo, Marcella; Cibinel, Anna; Lilly, Simon J.; Schawinski, Kevin (2016)
    We present the results of a pilot XMM-Newton and Chandra program aimed at studying the diffuse intragroup medium (IGM) of optically selected nearby groups from the Zurich ENvironmental Study (ZENS) catalog. The groups are in a narrow mass range about 10(13) M-circle dot, a mass scale at which the interplay between the IGM and the group member galaxies is still largely unprobed. X-ray emission from the IGM is detected in the energy band 0.5-2 keV with flux