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J/ApJ/708/584               SEXSI Spitzer catalog                (Eckart+, 2010)

A comparison of X-ray and mid-infrared selection of obscured active galactic nuclei. Eckart M.E., McGreer I.D., Stern D., Harrison F.A., Helfand D.J. <Astrophys. J., 708, 584-597 (2010)> =2010ApJ...708..584E
ADC_Keywords: Active gal. nuclei ; Photometry, infrared ; X-ray sources Keywords: galaxies: active - infrared: galaxies - X-rays: galaxies Abstract: We compare the relative merits of active galactic nuclei (AGNs) selection at X-ray and mid-infrared wavelengths using data from moderately deep fields observed by both Chandra and Spitzer. The X-ray-selected AGN sample and associated photometric and spectroscopic optical follow-up are drawn from a subset of fields studied as part of the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program. Mid-infrared data in these fields are derived from targeted and archival Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the Infrared Array Camera (IRAC) color-color AGN "wedge" selection technique. Nearly all X-ray sources in these fields which exhibit clear spectroscopic signatures of AGN activity have mid-infrared colors consistent with IRAC AGN selection. These are predominantly the most luminous X-ray sources. X-ray sources that lack high-ionization and/or broad lines in their optical spectra are far less likely to be selected as AGNs by mid-infrared color selection techniques. The fraction of X-ray sources identified as AGNs in the mid-infrared increases monotonically as the X-ray luminosity increases. Conversely, only 22% of mid-infrared-selected AGNs are detected at X-ray energies in the moderately deep (texp∼100ks) SEXSI Chandra data. Description: We have expanded the multiwavelength data available for six SEXSI fields by obtaining Spitzer imaging observations. All six fields have deep Chandra X-ray images, optical imaging, and extensive, deep optical spectroscopy - all of which has been published in Harrison et al. (2003, Cat. J/ApJ/596/944), Eckart et al. (2005, Cat. J/ApJS/156/35), and Eckart et al. (2006, Cat. J/ApJS/165/19). We obtained mid-infrared imaging through both archival and targeted Spitzer programs which include imaging at 3.6, 4.5, 5.8, and 8um from IRAC (PID 00017, 00064, 20694 and 20808) and imaging at 24um from MIPS (PID 20808 and 00083). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 187 290 SEXSI-Spitzer catalog
See also: J/ApJ/660/167 : Spitzer AGN candidates in CDFN (Donley+, 2007) J/A+A/466/823 : Hard 2-10kev X-ray selected sources (Georgantopoulos+, 2007) J/ApJS/165/19 : SEXSI catalog. III (Eckart+, 2006) J/ApJS/156/35 : SEXSI catalog. II (Eckart+, 2005) J/AJ/129/2074 : Faint Chandra sources in SWIRE (Franceschini+, 2005) J/ApJ/596/944 : SEXSI catalog (Harrison+, 2003) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 16 A16 --- CXOSEXSI The IAU-registered name (JHHMMSS.s+DDMMSS) 18- 19 I2 h RAh [08,22] Hour of Right Ascension (J2000) (1) 21- 22 I2 min RAm Minute of Right Ascension (J2000) (1) 24- 28 F5.2 s RAs Second of Right Ascension (J2000) (1) 30 A1 --- DE- [+] Sign of the Declination (J2000) (1) 31- 32 I2 deg DEd [03,67] Degree of Declination (J2000) (1) 34- 35 I2 arcmin DEm Arcminute of Declination (J2000) (1) 37- 40 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1) 42- 45 F4.1 arcsec delRA Corrected X-ray/Spitzer Right Ascension position difference (2) 47- 50 F4.1 arcsec delDE Corrected X-ray/Spitzer Declination position difference (2) 52- 59 F8.2 aW/m2 Hflux Galactic absorption adjusted 2-10keV flux; in units of 10-15erg/cm2/s 61- 65 F5.2 --- HR Hardness Ratio (3) 67 A1 --- l_Rmag [0/1] Limit flag on Rmag: 1=Rmag is a lower limit (0= Rmag is actual) 69- 73 F5.2 mag Rmag ? The R band magnitude 75 I1 --- n_Rmag [1,6] Optical ID Flag (4) 77- 81 F5.2 [-] logFxFo ? Log of Hflux (2-10keV) to optical flux ratio 83- 88 A6 --- Class Object type (5) 90- 94 F5.3 --- z ? Redshift 96- 99 F4.1 [10-7W] logLx ? Log of 2-10keV luminosity in erg/s (6) 101-104 F4.1 [cm-2] nH ? Log of H column density 107 A1 --- l_nH [ <]? Flag on nH (7) 109-114 F6.1 uJy F3.6 ? Flux in Spitzer/IRAC 3.6um image 116-121 F6.1 uJy e_F3.6 ? Error in F3.6 123 I1 --- f_F3.6 [0,7] Flag on F3.6 (8) 125-130 F6.1 uJy F4.5 ? Flux in Spitzer/IRAC 4.5um image 132-137 F6.1 uJy e_F4.5 ? Error in F4.5 139 I1 --- f_F4.5 [0,7] Flag on F4.5 (8) 141-146 F6.1 uJy F5.8 ? Flux in Spitzer/IRAC 5.6um image 148-153 F6.1 uJy e_F5.8 ? Error in F5.8 155 I1 --- f_F5.8 [0,8] Flag on F5.8 (8) 157-162 F6.1 uJy F8.0 ? Flux in Spitzer/IRAC 8.0um image 164-169 F6.1 uJy e_F8.0 ? Error in F8.0 171 I1 --- f_F8.0 [0,8] Flag on F8.0 (8) 173-178 F6.1 uJy F24 ? Flux in Spitzer/MIPS 24um image 180-185 F6.1 uJy e_F24 ? Error in F24 187 I1 --- f_F24 [0,8] Flag on F24 (8)
Note (1): Positions are determined by SExtractor from Spitzer astrometry. Note (2): Corrected x-ray position determined from SEXSI II (Cat. J/ApJS/156/35), >0 if Spitzer is greater. Note (3): Ratio=(H-S)/(H+S) where H is the corrected counts in the 2.0-10keV band and S is the corrected counts in the 0.5-2.0keV band extracted at the position of the hard band detection. Note (4): Optical flag as follows: 6 = non-detection but near bright source (limiting mag will be incorrect); 5 = unclear which source is optical counterpart; 4 = near bright source (magnitude affected); 3 = bright source - magnitude taken from Guide Star Catalog II; 2 = upper limit; 1 = optical identification; 0 = no optical coverage. Note (5): Object type as follows: BLAGN = Broad Line Active Galactic Nucleus; NLAGN = Narrow Line Active Galactic Nucleus; ELG = Emission Line Galaxy; ALG = Absorption Line Galaxy; unid = No Spectroscopic Observations; cont = Continuum Only Spectrum; star = any type of star; Note (6): See SEXSI III (Cat. J/ApJS/165/19). Note (7): Flag on nH as follows: S = Source detected on off-axis ACIS-S chip (2-3) and thus nH is calculated from HR, not spectral fit. See SEXSI III (Cat. J/ApJS/165/19), Section 5. < = When a nH measurement is zero we report '<' in the corresponding flag column. > = nH is a lower limit (occurs when HR is a lower limit and nH derived from HR). H = Bad XSPEC fit. nH is calculated from HR, not spectral fit. Note (8): Flag as follows: 8 = below nominal 5-sigma detection limit; 7 = likely counterpart outside formal match radius; 6 = non-detection but near bright source (limiting mag will be incorrect); 5 = unclear which source is optical counterpart; 4 = near bright source (magnitude affected); 3 = not used; 2 = upper limit; 1 = infrared identification; 0 = no infrared coverage.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 02-Feb-2012
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