THE CHANDRA COSMOS-LEGACY SURVEY: THE z &gt; 3 SAMPLE

Marchesi, S.; Civano, F.; Salvato, M.; Shankar, Francesco; Comastri, A.; Elvis, M.; Lanzuisi, G.; Trakhtenbrot, Benny; Vignali, C.; Zamorani, G.; Allevato, V.; Brusa, M.; Fiore, F.; Gilli, R.; Griffiths, R. E.; Hasinger, G.; Miyaji, Takeshi; Schawinski, Kevin; Treister, Ezequiel; Urry, C. Megan

doi:10.3847/0004-637x/827/2/150

Cited by 46 publications

(94 citation statements)

References 102 publications

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“…20 is consistent with previous results by, e.g., Hiroi et al (2012), Kalfountzou et al (2014), Vito et al (2014), andMarchesi et al (2016) (i.e., Φ ∝ (1 + z) p with p ∼ −6, see Tab. 3).…”

Section: The Agn Xlf At High Redshiftsupporting

confidence: 93%

“…Taking fully into account the probability distribution functions (PDF) of the photometric redshifts for sources lacking spectroscopic identifications (see e.g. Marchesi et al 2016 for a similar use of the photometric redshifts), the final sample consists of ≈ 102 X-ray detected AGN at 3 z < 6. The number of sources contributing to this sample with their PDF(z) is 118.…”

Section: Introductionmentioning

confidence: 99%

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High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

Vito

Brandt

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

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157

184

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We investigate the population of high-redshift (3 z < 6) AGN selected in the two deepest X-ray surveys, the 7 Ms Chandra Deep Field-South and 2 Ms Chandra Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-L * regime (logL X 44), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of ≈ 102 X-ray selected AGN at 3 z < 6. The fraction of AGN obscured by column densities logN H > 23 is ∼ 0.6 − 0.8, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to F 0.5−2 keV = 7 × 10 −18 erg cm −2 s −1 , extending previous results to fainter fluxes, especially at z > 4. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space-density, in particular, declines at z > 3 at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black-hole accretion rate density and star-formation rate density, which are usually found to evolve similarly at z 3, appear to diverge at higher redshifts.

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Section: The Agn Xlf At High Redshiftsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

Vito

Brandt

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

Self Cite

157

184

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“…For the UV AGN LF, we consider the functional forms proposed by Willott et al (2010) and Kashikawa et al (2015), and for the X-ray AGN LF, the upper and lower limits derived from a combination of LFs and upper limits from Vito et al (2016) and Marchesi et al (2016).…”

Section: Agn Spectramentioning

confidence: 99%

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

Volonteri

Reines

Atek

et al. 2017

ApJ

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The first billion years of the Universe has been a pivotal time: stars, black holes (BHs), and galaxies formed and assembled, sowing the seeds of galaxies as we know them today. Detecting, identifying, and understanding the first galaxies and BHs is one of the current observational and theoretical challenges in galaxy formation. In this paper we present a population synthesis model aimed at galaxies, BHs, and active galactic nuclei (AGNs) at high redshift. The model builds a population based on empirical relations. The spectral energy distribution of galaxies is determined by age and metallicity, and that of AGNs by BH mass and accretion rate. We validate the model against observations, and predict properties of galaxies and AGN in other wavelength and/or luminosity ranges, estimating the contamination of stellar populations (normal stars and high-mass X-ray binaries) for AGN searches from the infrared to X-rays, and vice versa for galaxy searches. For high-redshift galaxies with stellar ages 1 Gyr < , we find that disentangling stellar and AGN emission is challenging at restframe UV/optical wavelengths, while high-mass X-ray binaries become more important sources of confusion in X-rays. We propose a color-color selection in the James Webb Space Telescope bands to separate AGN versus star-dominated galaxies in photometric observations. We also estimate the AGN contribution, with respect to massive, hot, and metal-poor stars, at driving high-ionization lines, such as C IV and He II. Finally, we test the influence of the minimum BH mass and occupation fraction of BHs in low-mass galaxies on the restframe UV/near-IR and X-ray AGN luminosity function.

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“…) sources (e.g., Ueda et al 2003;La Franca et al 2005;Polletta et al 2006;Vito et al 2014;Marchesi et al 2016). However, these surveys were biased against the detection of AGNs obscured by large columns of gas (N H >10 24 cm −2 ), called Compton-thick (CT) AGNs, mainly in the local universe, up to z 1  .…”

Section: Introductionmentioning

confidence: 99%

The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS Field

Masini

Civano

Comastri

et al. 2018

ApJS

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We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR's ECDFS and COSMOS surveys. The survey covers a ∼0.6 deg 2 area of the field for a total observing time of ∼1.75 Ms, to a half-area depth of ∼155 ks corrected for vignetting at 3-24 keV, and reaching sensitivity limits at half-area in the full (3-24 keV), soft (3-8 keV), and hard (8-24 keV) bands of 2.2×10 −14 erg cm −2 s −1 , 1.0×10 −14 erg cm −2 s −1 , and 2.7×10 −14 erg cm −2 s −1 , respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of z 1.1 á ñ~. Through a broadband (0.5-24 keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N H >10 24 cm −2 ) fraction. Taking into account the uncertainties on each N H measurement, the final number of CT sources is 6.8±1.2. This corresponds to an observed CT fraction of 11.5%±2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.

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THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

Cited by 46 publications

References 102 publications

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS Field

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