J/ApJS/185/433 SWIRE/Chandra survey in Lockman Hole Field (Wilkes+, 2009) ================================================================================ The SWIRE/Chandra survey: the X-ray sources. Wilkes B.J., Kilgard R., Kim D.-W., Kim M., Polletta M., Lonsdale C., Smith H.E., Surace J., Owen F.N., Franceschini A., Siana B., Shupe D. =2009ApJS..185..433W ================================================================================ ADC_Keywords: X-ray sources ; Photometry, infrared ; Photometry, ugriz ; Cross identifications ; Surveys ; Active gal. nuclei Keywords: catalogs - quasars: general - surveys - X-rays: galaxies Abstract: We report a moderate-depth (70ks), contiguous 0.7deg^2^ Chandra survey in the Lockman Hole Field of the Spitzer/SWIRE Legacy Survey coincident with a completed, ultra-deep VLA survey with deep optical and near-infrared imaging in-hand. The primary motivation is to distinguish starburst galaxies and active galactic nuclei (AGNs), including the significant, highly obscured (logN_H_>23) subset. Chandra has detected 775 X-ray sources to a limiting broadband (0.3-8keV) flux ~4x10^-16^erg/cm^2^/s. We present the X-ray catalog, fluxes, hardness ratios, and multi-wavelength fluxes. The logN versus logS agrees with those of previous surveys covering similar flux ranges. The Chandra and Spitzer flux limits are well matched: 771 (99%) of the X-ray sources have infrared (IR) or optical counterparts, and 333 have MIPS 24um detections. There are four optical-only X-ray sources and four with no visible optical/IR counterpart. The very deep (~2.7uJy rms) VLA data yield 251 (>4{sigma}) radio counterparts, 44% of the X-ray sources in the field. More than 40% of the X-ray sources in the VLA field are radio-loud using the classical definition, RL. The majority of these are red and relatively faint in the optical so that the use of RL to select those AGNs with the strongest radio emission becomes questionable. Using the 24um to radio flux ratio (q_24_) instead results in 13 of the 147 AGNs with sufficient data being classified as radio-loud, in good agreement with the ~10% expected for broad-lined AGNs based on optical surveys. We conclude that q_24_ is a more reliable indicator of radio-loudness. Use of RL should be confined to the optically selected type 1 AGN. Description: We have obtained Chandra ACIS-I observations in a 3x3 raster of a contiguous 0.7deg^2^ area of sky within the Lockman Hole region of the SWIRE survey. Nine observations were obtained between 2004 September 12 and 26. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table34.dat 133 775 SWIRE X-ray sources (table 3 and 4 of the paper) table7.dat 190 775 SWIRE X-ray sources: Multi-Wavelength Fluxes -------------------------------------------------------------------------------- See also: J/AJ/129/2074 : Faint Chandra sources in SWIRE (Franceschini+, 2005) J/ApJ/642/673 : IR-selected obscured AGN candidates (Polletta+, 2006) http://cosmosdb.iasf-milano.inaf.it/CHANDRA-SWIRE/index.jsp : SWIRE/Chandra database Home page Byte-by-byte Description of file: table34.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- --- [CXOSW] 6- 21 A16 --- CXOSW Source identification (JHHMMSS.s+DDMMSS) 23- 24 I2 h RAh Hours of Right Ascention (J2000) 26- 27 I2 min RAm Minutes of Right Ascention (J2000) 29- 33 F5.2 s RAs Seconds of Right Ascention (J2000) 35 A1 --- DE- Declination sign (J2000) 36- 37 I2 deg DEd Degree of Declination (J2000) 39- 40 I2 arcmin DEm Arcminute of Declination (J2000) 42- 45 F4.1 arcsec DEs Arcsecond of Declination (J2000) 47- 51 F5.2 arcsec e_pos Position error 53- 58 F6.1 ct Xcts Net 0.3-8.0keV counts 60- 63 F4.1 ct e_Xcts Error on Xcts 65- 72 E8.2 ct/s Xrate Net 0.3-8.0keV count rate 74- 81 E8.2 ct/s e_Xrate Error on Xrate 83- 90 E8.2 mW/m2/Hz S1keV The 1keV flux density (1) 92- 99 E8.2 mW/m2 Fbroad Broad 0.3-8.0keV flux (1) 101-108 E8.2 mW/m2 Fsoft ? Soft 0.3-2.5keV flux (1) 110-117 E8.2 mW/m2 Fhard ? Hard 2.5-8.0keV flux (1) 119-123 F5.2 --- HR Hardness ratio (2) 125-128 F4.2 --- E_HR Upper error on HR 130-133 F4.2 --- e_HR Lower error on HR -------------------------------------------------------------------------------- Note (1): Assumes Galactic N_H_ and {Gamma}=1.7, in units of erg/cm^2^/s (Flux) and erg/cm^2^/s/Hz (Flux density). Note (2): HR=(H-S)/(H+S), where H = counts in hard band (2.5-8keV), S = Counts in the soft band (0.3-2.5keV), determined using a Bayesian approach which is applicable for low count sources (see text). -------------------------------------------------------------------------------- Byte-by-byte Description of file: table7.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- --- [CXOSW] 7- 22 A16 --- CXOSW Source identification (JHHMMSS.s+DDMMSS) 24- 29 I6 --- SWIRE ?=-99 SWIRE identification 31- 35 F5.2 arcsec DPOS ?=-9.99 Distance between X-ray and SWIRE sources 37- 42 F6.2 mag rmag The r' band magnitude (1) 44- 47 F4.2 mag e_rmag ?=0 The error in rmag 49- 54 F6.2 mag gmag The g' band magnitude (1) 56- 59 F4.2 mag e_gmag ?=0 The error in gmag 61- 68 F8.2 uJy F3.6 The 3.6 micron flux density (1) 70- 74 F5.2 uJy e_F3.6 ?=0 The error in F3.6 76- 83 F8.2 uJy F8.0 The 8.0 micron flux density (1) 85- 89 F5.2 uJy e_F8.0 ?=0 The error in F8.0 91- 96 F6.1 uJy F24 The 24 micron flux density (1) 98-102 F5.2 uJy e_F24 ?=0 The error in F24 104-110 F7.1 uJy F20cm The 20cm flux density (1) 112-117 F6.1 uJy e_F20cm ?=0 The error in F20cm 119-190 A72 --- Notes Notes -------------------------------------------------------------------------------- Note (1): Negative values indicate a 4{sigma} upper limit for the radio and 5{sigma} for Spitzer and optical fluxes. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Mar-2010