J/MNRAS/445/1430 C-COSMOS & ChaMP X-ray-selected z>3 AGNs (Kalfountzou+, 2014)
The largest X-ray-selected sample of z>3 AGNs: C-COSMOS and ChaMP.
Kalfountzou E., Civano F., Elvis M., Trichas M., Green P.
<Mon. Not. R. Astron. Soc., 445, 1430-1448 (2014)>
=2014MNRAS.445.1430K 2014MNRAS.445.1430K (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources
Keywords: surveys - galaxies: active - X-rays: galaxies
Abstract:
We present results from an analysis of the largest high-redshift (z>3)
X-ray-selected active galactic nucleus (AGN) sample to date, combining
the Chandra Cosmological Evolution Survey and Chandra Multi-wavelength
Project surveys and doubling the previous samples. The sample
comprises 209 X-ray-detected AGNs, over a wide range of rest-frame
2-10keV luminosities logLX=43.3-46.0erg/s. X-ray hardness rates show
that ∼39 per cent of the sources are highly obscured,
NH>1022cm-2, in agreement with the ∼37 per cent of type-2 AGNs
found in our sample based on their optical classification. For ∼26
per cent of objects have mismatched optical and X-ray classifications.
Utilizing the 1/Vmax method, we confirm that the comoving space
density of all luminosity ranges of AGNs decreases with redshift above
z>3 and up to z∼7. With a significant sample of AGNs (N=27) at z>4, it
is found that both source number counts in the 0.5-2keV band and
comoving space density are consistent with the expectation of a
luminosity-dependent density evolution (LDDE) model at all redshifts,
while they exclude the luminosity and density evolution (LADE) model.
The measured comoving space density of type-1 and type-2 AGNs shows a
constant ratio between the two types at z>3. Our results for both AGN
types at these redshifts are consistent with the expectations of LDDE
model.
Description:
The high-redshift AGN sample used in this work has been selected from
the C-COSMOS X-ray catalogue, combining the spectroscopic and
photometric information available from the identification catalogue of
X-ray C-COSMOS sources (Civano et al., 2011ApJ...741...91C 2011ApJ...741...91C, 2012, Cat.
J/ApJS/201/30) and the ChaMP (Chandra Multi-wavelength Project) X-ray
catalogue using only the 323 ChaMP obsids overlapping with Sloan
Digital Sky Survey (SDSS; Richards et al., 2006, Cat. J/AJ/131/2766)
DR5 imaging.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 91 209 Properties of the high-redshift AGN sample
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See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
J/ApJS/150/19 : ChaMP. I. First X-ray source catalog (Kim+, 2004)
J/ApJ/645/955 : ChaMP serendipitous galaxy cluster survey (Barkhouse+, 2006)
J/AJ/131/2766 : Quasar luminosity function from SDSS-DR3 (Richards+, 2006)
J/ApJS/201/30 : The Chandra COSMOS survey. III. (Civano+, 2012)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Survey [1/2] survey: 1 = ChaMP; 2 = C-COSMOS
3- 10 F8.4 deg RAdeg Right ascension (J2000)
12- 18 F7.4 deg DEdeg Declination (J2000)
20- 24 F5.3 --- zspec ?=- Spectroscopic redshift
26- 30 F5.3 --- zphot ?=- Photometric redshift
32 A1 --- lbzphot Limit flag on b_zphot
33- 37 F5.3 --- b_zphot ?=- Photometric redshift lower limit
39- 43 F5.3 --- B_zphot ?=- Photometric redshift upper limit
45 I1 --- OType1 [1/2]?=- Optical type (1)
47 I1 --- XType [1/2]?=- X-ray type based on
NH=1022cm-2 limit (2)
49- 54 F6.3 10-16W/m2 Ssoft The 0.5-2keV flux converted to {GAMMA}=1.8 (3)
56- 61 F6.3 [10-7W] logLX The 2-10keV luminosity in units of erg/s
62- 67 F6.3 --- HR ?=- Hardness ratio (4)
69- 74 F6.3 --- b_HR ?=- HR lower limit
76- 81 F6.3 --- B_HR ?=- HR upper limit
83- 84 A2 --- l_NH [<≥ ] Limit flag on NH
85- 91 F7.2 10+22cm-2 NH ?=- The absorption column density
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Note (1): Optical type as follows:
1 = type-1 AGN
2 = type-2 AGN
Note (2): X-ray type as follows:
1 = unobscured AGNs
2 = obscured AGNs
Note (3): in units of 10-13erg/cm2/s. For sources undetected in soft band a
negative symbol is given and the flux estimated by the hard or full band
detection.
Note (4): defined as HR=(H+S)/(H-S), S: 0.5-2.0keV count rate and
H: 2.0-10keV count rate.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Dec-2015