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J/ApJS/232/8  16yrs of AGNs X-ray spectral analyses from 7Ms CDF-S  (Liu+, 2017)

X-ray spectral analyses of AGNs from the 7Ms Chandra Deep Field-South survey: the distribution, variability, and evolutions of AGN obscuration. Liu T., Tozzi P., Wang J.-X., Brandt W.N., Vignali C., Xue Y., Schneider D.P., Comastri A., Yang G., Bauer F.E., Paolillo M., Luo B., Gilli R., Wang Q.D., Giavalisco M., Ji Z., Alexander D.M., Mainieri V., Shemmer O., Koekemoer A., Risaliti G. <Astrophys. J. Suppl. Ser., 232, 8-8 (2017)> =2017ApJS..232....8L (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Redshifts Keywords: catalogs; galaxies: active; galaxies: evolution; surveys; X-rays: galaxies Abstract: We present a detailed spectral analysis of the brightest active galactic nuclei (AGNs) identified in the 7Ms Chandra Deep Field-South (CDF-S) survey over a time span of 16 years. Using a model of an intrinsically absorbed power-law plus reflection, with possible soft excess and narrow Fe Kα line, we perform a systematic X-ray spectral analysis, both on the total 7Ms exposure and in four different periods with lengths of 2-21 months. With this approach, we not only present the power-law slopes, column densities NH, observed fluxes, and absorption-corrected 2-10keV luminosities LX for our sample of AGNs, but also identify significant spectral variabilities among them on timescales of years. We find that the NH variabilities can be ascribed to two different types of mechanisms, either flux-driven or flux-independent. We also find that the correlation between the narrow Fe line EW and NH can be well explained by the continuum suppression with increasing NH. Accounting for the sample incompleteness and bias, we measure the intrinsic distribution of NH for the CDF-S AGN population and present reselected subsamples that are complete with respect to NH. The NH-complete subsamples enable us to decouple the dependences of NH on LX and on redshift. Combining our data with those from C-COSMOS, we confirm the anticorrelation between the average NH and LX of AGN, and find a significant increase of the AGN-obscured fraction with redshift at any luminosity. The obscured fraction can be described as fobscured∼0.42(1+z)0.60. Description: The 7Ms CDF-S survey is comprised of observations performed between 1999 October 14, and 2016 March 24, (UTC). Excluding one observation compromised by telemetry saturation and other issues (ObsID 581), there are 102 observations (observation IDs listed in Table 1) in the data set. The exposures collected across 16 years can be grouped into four distinct periods, each spanning 2-21 months. Table 1: --------------------------------------------------------------------------- Period Observation Date Time Span Exposure Time --------------------------------------------------------------------------- I 1999.10-2000.12 14 months 1Ms 11 ObsIDs: 1431-0 1431-1 441 582 2406 2405 2312 1672 2409 2313 2239 II 2007.09-2007.11 2 months 1Ms 12 ObsIDs: 8591 9593 9718 8593 8597 8595 8592 8596 9575 9578 8594 9596 III 2010.03-2010.07 4 months 2Ms 31 ObsIDs: 12043 12123 12044 12128 12045 12129 12135 12046 12047 12137 12138 12055 12213 12048 12049 12050 12222 12219 12051 12218 12223 12052 12220 12053 12054 12230 12231 12227 12233 12232 12234 IV 2014.06-2016.03 21 months 3Ms 48 ObsIDs: 16183 16180 16456 16641 16457 16644 16463 17417 17416 16454 16176 16175 16178 16177 16620 16462 17535 17542 16184 16182 16181 17546 16186 16187 16188 16450 16190 16189 17556 16179 17573 17633 17634 16453 16451 16461 16191 16460 16459 17552 16455 16458 17677 18709 18719 16452 18730 16185 --------------------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 70 1100 Counts and fluxes of each source in each observation period table3.dat 114 315 Spectral properties table4.dat 49 50 Narrow Fe Kα lines table5.dat 49 5 Broad Fe Kα lines
See also: J/ApJS/121/473 : A diagnostic diagram for Seyfert 2 Galaxies (Bassani+, 1999) J/ApJS/139/369 : Chandra Deep Field South. 1 Ms catalog (Giacconi+, 2002) J/AJ/126/539 : The Chandra Deep Fields North and South (Alexander+, 2003) J/ApJS/161/21 : Extended Chandra Deep Field-South survey (Lehmer+, 2005) J/A+A/451/457 : X-ray properties of AGN in CDFS (Tozzi+, 2006) J/AJ/131/2373 : Extended Chandra Deep Field-South survey (Virani+, 2006) J/ApJ/681/1163 : Late-type galaxies in Chandra deep fields (Lehmer+, 2008) J/ApJS/179/19 : CDFS survey: 2 Ms source catalogs (Luo+, 2008) J/AJ/135/1505 : CDFs AGNs X-ray power-law photon index (Saez+, 2008) J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009) J/ApJS/180/102 : AEGIS-X: Chandra deep survey (Laird+, 2009) J/ApJ/728/58 : Swift-BAT survey of AGNs (Burlon+, 2011) J/A+A/533/A119 : GOODS-Herschel North and South catalogs (Elbaz+, 2011) J/ApJ/740/37 : Obscured AGN at z∼0.5-1 in the CDFS (Luo+, 2011) J/ApJ/742/3 : Photometric catalogs for ECDF-S and CDF-N (Rafferty+, 2011) J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011) J/ApJ/754/45 : IR properties of Swift/BAT X-ray AGNs (Ichikawa+, 2012) J/MNRAS/420/2190 : ECDFS sources with radio counterparts (Vattakunnel+, 2012) J/ApJ/748/124 : AGN X-ray variability in the 4Ms catalog (Young+, 2012) J/MNRAS/436/3759 : ECDFS sources optical/IR counterparts (Bonzini+, 2013) J/A+A/556/A114 : Obscured AGNs in CDF-S (Castello-Mor+, 2013) J/A+A/555/A42 : The XMM-CDFS catalogues (Ranalli+, 2013) J/MNRAS/443/1999 : X-ray spectral analysis of AGNs (Brightman+, 2014) J/A+A/564/A125 : AGN Torus model comparison of AGN in the CDFS (Buchner+, 2014) J/ApJ/802/89 : Luminosity function of X-ray-selected AGNs (Buchner+, 2015) J/A+A/576/A130 : Ultra-deep cat. of X-ray groups in ECDF-S (Finoguenov+, 2015) J/ApJ/807/129 : X-ray to MIR luminosities relation of AGNs (Stern, 2015) J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016) J/ApJ/825/7 : Evolution of ∼6Ms CDF-S galaxies (Lehmer+, 2016) J/A+A/593/A55 : MEXSAS catalogue (Vagnetti+, 2016) J/ApJS/224/15 : Improved 2Ms and 250ks Chandra catalogs (Xue+, 2016) J/ApJ/831/145 : 6Ms Chandra long-term analyses of AGNs (Yang+, 2016) J/ApJ/835/74 : IR photom. of AGNs in Swift/BAT 70month cat. (Ichikawa+, 2017) J/ApJS/228/2 : Chandra Deep Field-South survey: 7Ms sources (Luo+, 2017) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID [20/988] Identifier from Luo+ 2017, J/ApJS/228/2 6- 8 A3 --- Per Observation period (see the "Description" section above) 10- 14 I5 ct Scts [0/13061] Soft band (0.5-2keV) counts 16- 18 I3 ct e_Scts [1/115] Uncertainty in Scts 20- 23 I4 ct Hcts [0/7706] Hard band (2-7keV) counts 25- 26 I2 ct e_Hcts [4/90] Uncertainty in Hcts 28- 34 F7.3 10-16mW/m2 FS [0/680] Soft band (0.5-2keV) flux 36- 41 F6.3 10-16mW/m2 e_FS [0/64] Lower uncertainty in FS 43- 48 F6.3 10-16mW/m2 E_FS [0.02/39] Upper uncertainty in FS 50- 56 F7.3 10-16mW/m2 FH [0/816] Hard band (2-7keV) flux 58- 63 F6.3 10-16mW/m2 e_FH [0/28] Lower uncertainty in FH 65- 70 F6.3 10-16mW/m2 E_FH [0.2/37] Upper uncertainty in FH
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Cpt Compton ("thick": 22 occurrences or "thin") 7- 10 I4 --- ID [20/988] Identifier in the 7Ms CDF-S catalog (Luo+ 2017, J/ApJS/228/2) 12- 17 F6.4 --- z [0.1/5.3] Redshift from Luo+, 2017, J/ApJS/228/2 18 A1 --- f_z Flag on z (s=secure spectroscopic) (1) 20- 28 A9 --- Per Observation period (see the "Description" section above) (2) 30 A1 --- l_NH Limit flag on NH 31- 37 F7.3 10+22/cm2 NH [0.005/600] Hydrogen column density (3) 39- 45 F7.3 10+22/cm2 e_NH [0.005/514]? Lower 90% uncertainty in NH 47- 53 F7.3 10+22/cm2 E_NH [0/554]? Upper 90% uncertainty in NH 55- 58 F4.2 --- Gamma [1.4/2.4]? Power-law slope 59 A1 --- f_Gamma [f] f=fixed 61- 64 F4.2 --- e_Gamma [0.02/0.4]? Lower 90% uncertainty in Gamma 66- 69 F4.2 --- E_Gamma [0.02/0.4]? Upper 90% uncertainty in Gamma 71- 77 E7.1 ph/cm2/s SRate ? Soft band (0.5-2keV) net count rate; in photon/cm2/s units (4) 79- 85 E7.1 ph/cm2/s HRate ? Hard band (2-7keV) net count rate in photon/cm2/s units (4) 87- 91 F5.2 [10-7W] logL [39.5/48]? log 2-10keV unabsorbed luminosity; in erg/s (5) 93- 96 F4.2 [10-7W] e_logL [0/3]? Lower 90% uncertainty in logL 98-101 F4.2 [10-7W] E_logL [0/5]? Upper 90% uncertainty in logL 103-106 F4.1 --- C-NH [-1/24] Completeness flag (6) 108-114 A7 --- Model Period number in which soft excess component added (see the "Description" section above) (7)
Note (1): Flag on redshift as follows: s = secure spectroscopic (148 occurrences); i = insecure spectroscopic (26 occurrences); p = photometry (97 occurrences) x = X-ray spectroscopic-z (5 occurrences). Note (2): If NH is found variable. This field is empty if NH is not variable. If more than one period is given in one line, their NH are set as the same. If one period of a source whose NH is variable is not given in the table, its NH is set as the average of the NH of the other periods. Note (3): Note the NH for Compton-thick sources are considered unreliable and not used in this work. Note (4): Averaged among the four periods, weighted by the exposure time. Note (5): This value is highly uncertain in the cases of extreme Compton-thick absorption, where the transmitted power-law becomes too weak. Note (6): Use the filter C-NH≥NH to select a subsample which is complete with respect to NH at logNH<NH, where NH can be 23, 23.5, or 24. -1 means Compton-thick. Note (7): 0 means soft excess is found in the 7Ms stacked spectrum. Empty means no soft excess is found.
Byte-by-byte Description of file: table[45].dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID [26/988] Identifier 6- 9 F4.2 keV Energy [6/6.7] Rest-frame central energy 11- 14 F4.2 keV e_Energy Negative 1σ error on Energy 16- 19 F4.2 keV E_Energy Positive 1σ error on Energy 21- 24 I4 eV EW [66/2569] Rest-frame equivalent-width 26- 29 I4 eV e_EW Negative 1σ error on EW 31- 34 I4 eV E_EW Positive 1σ error on EW 36- 39 F4.2 keV sigma [0.2/3]? Rest-frame width (only for table 5) 41- 44 F4.2 keV e_sigma ? Negative 1σ error on sigma 46- 49 F4.2 keV E_sigma ? Positive 1σ error on sigma
History: From electronic version of the journal Acknowledgements: Teng Liu [lewtonstein {at} gmail . com]
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 29-Sep-2017
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