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J/A+A/466/823  Hard 2-10kev X-ray selected sources      (Georgantopoulos+, 2007)

Chandra and Spitzer observations of CDFS X-ray obscured QSOs. Georgantopoulos I., Georgakakis A., Akylas A. <Astron. Astrophys., 466, 823-830 (2007)> =2007A&A...466..823G
ADC_Keywords: X-ray sources ; QSOs ; Active gal. nuclei ; Redshifts Keywords: galaxies: active - galaxies: quasars: general - X-rays: galaxies - X-rays: general Abstract: We present Chandra and Spitzer data for the 186, extragalactic, hard 2-10keV X-ray selected sources, which lie in the central part of the Chandra Deep Field South (CDFS). For the vast majority of sources (99.5%), there is a spectroscopic or photometric redshift available. We classify 17 sources as X-ray obscured QSOs, strictly according to X-ray criteria, i.e. defined as having large hydrogen column densities (NH>1022cm-2^) and luminosities (LX>1044erg/s). The surface density of X-ray obscured QSOs is ∼210°-2. We find 18 candidate Compton-thick NH>1024cm-2 sources, of which three have QSO luminosities (LX>1044erg/s). The X-ray obscured QSO comprise a mixed bag of objects, covering the redshift range z=1.3-4.3. Eight of these show narrow-line optical spectra, two show no obscuration in their optical spectra that present broad lines, while for the other seven there is only a photometric redshift available. About half of the X-ray obscured QSOs show high X-ray to optical flux ratios, X/O>1, and red colours, I-3.6µm>4. Combining the X-ray with the mid-IR 8µm or 24µm flux can be used as an additional diagnostic to sift out the heavily obscured AGN. All X-ray selected QSOs present red mid-IR colours and can be easily separated among mid-IR sources, demonstrating that mid-IR selection provides a powerful tool for detecting obscured QSOs. Description: The 1Ms CDFS data consist of 11 individual Chandra (Advanced CCD Imaging Spectrometer) ACIS-I pointings with the aim points separated by a few arcseconds. The 247 sources were detected in the 2-10keV band down to a flux limit of 2x10-16erg/cm2/s (Gamma=1.4). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 92 186 Spectral fits
See also: J/ApJ/610/128 : NIR colors of hard X-ray-selected AGN (Watanabe+, 2004) J/ApJ/618/123 : Hard X-ray-emitting AGNs (Silverman+, 2005) J/A+A/467/73 : 3σ hard sample of XMDS survey (Tajer+, 2007) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [GZW2002] Sequential number, [GZW2002] XID NNN in Simbad 4 A1 --- n_[GZW2002] [*] *: Compton-thick sources 6- 21 A16 --- Name Source name from Giacconni et al. (2002, Cat. J/ApJS/139/369) JHHMMSS.s+DDMMSS 23- 27 F5.2 --- Gamma Best fit model power-law photon index 29- 32 F4.2 --- E_Gamma ? Error on Gamma (upper limit) 34- 37 F4.2 --- e_Gamma ? Error on Gamma (lower limit) 39 A1 --- l_NH Limit flag on NH 40- 46 F7.2 10+22cm-2 NH Rest-frame column density 48 A1 --- f_NH [i] i when upper limit is infinity 49- 55 F7.2 10+22cm-2 E_NH ? Error on NH (upper limit) 57- 63 F7.2 10+22cm-2 e_NH ? Error on NH (lower limit) 65- 69 F5.2 10-7W logLX ?=- logarithm of 2-10keV intrinsic luminosity 71- 76 A6 --- Class Optical spectroscopic classification as given in Szokoly et al. (2004, J/ApJS/155/271) (1) 78- 82 F5.3 --- z ?=- Redshift from either Szokoly et al. (2004 J/ApJS/155/271) (spectroscopic) or Zheng et al. (2004, J/ApJS/155/73) (photometric) 84- 87 F4.2 10-17W/m2 Flux Observed 2-10keV X-ray flux 89- 92 F4.2 --- chi2/dof ?=- Reduced chi2
Note (1): Types defined in Szokoly et al. (2004, J/ApJS/155/271) as follows: BLAGN = Objects with emission lines broader than 2000km/s. This classification implies an optical type 1 AGN or QSO. HEX = Object with unresolved emission lines and exhibiting high ionization lines or emission line ratios indicating AGN activity. These objects are dominantly optical type 2 AGNs or QSOs, but in a few cases the optical type 1/2 distinction is not possible based on the data. LEX = Objects with unresolved emission lines consistent with an H II region-type spectra. These objects would be classified as normal galaxies based on the optical data alone as the presence of the AGN cannot be established. ABS = A typical galaxy spectrum showing only absorption lines BLLAC? = May be a BL Lac object M-star = M-type star star = A stellar spectrum
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Oct-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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