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J/ApJ/716/1217    Chandra SMC deep field sources                (Laycock+, 2010)

Exploring the Small Magellanic Cloud to the faintest X-ray fluxes: source catalog, timing, and spectral analysis. Laycock S., Zezas A., Hong J., Drake J.J., Antoniou V. <Astrophys. J., 716, 1217-1240 (2010)> =2010ApJ...716.1217L
ADC_Keywords: X-ray sources ; Pulsars ; Magellanic Clouds Keywords: Magellanic Clouds - stars: emission-line, Be - stars: neutron - X-rays: binaries Abstract: We present the results of a pair of 100ks Chandra observations in the Small Magellanic Cloud (SMC) to survey high-mass X-ray binaries (HMXBs), stars, and low-mass X-ray binaries (LMXBs)/cataclysmic variables down to Lx=4.3x1032erg/s. The two SMC Deep Fields (DFs) are located in the most active star-forming region of the bar, with Deep Field-1 positioned at the most pulsar-rich location identified from previous surveys. Two new pulsars were discovered in the outburst: CXOU J004929.7-731058 (P=892s), CXOU J005252.2-721715 (P=326s), and three new HMXB candidates were identified. Of the 15 Be-pulsars now known in the field, 13 were detected, with pulsations seen in 9 of them. Bright optical counterparts exist for 40 of the X-ray sources, of which 33 are consistent with early-type stars (MV←2, B-V<0.2), and are the subject of a companion paper. The results point to an underlying HMXB population density up to double that of active systems. The full catalog of 394 point sources is presented along with detailed analyses of timing and spectral properties. Description: Each of the two SMC fields was observed for a total of 100ks with Chandra's Advanced CCD Imaging Spectrometer (ACIS) in 21,22,23 November 2006 for Deep Field-2 (DF2) and 25,26 April 2006 for Deep Field-1 (DF1) (obsID 8479, 7156, 8481 and 7155, 7327, respectively). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 393 394 Chandra SMC deep fields source catalog table3.dat 84 18 Pulsars detected in the Chandra data
See also: B/chandra : The Chandra Archive Log (CXC, 1999-2012) J/ApJ/697/1695 : The Chandra survey of the SMC "Bar". II. (Antoniou+, 2009) J/PASJ/55/161 : ASCA sources in the SMC (Yokogawa+, 2003) J/A+AS/142/41 : SMC X-ray sources ROSAT PSPC catalogue (Haberl+, 2000) J/A+AS/147/75 : ROSAT HRI catalogue of SMC X-ray sources (Sasaki+, 2000) J/A+AS/136/81 : A ROSAT PSPC X-Ray Survey of the SMC (Kahabka, 1999) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 A5 --- --- [CXOPS] 6- 21 A16 --- CXOU Source name (JHHMMSS.s+DDMMSS) 23- 32 F10.7 deg RAdeg Right Ascension in decimal degrees (J2000) 34- 44 F11.7 deg DEdeg Declination in decimal degrees (J2000) 46- 49 F4.2 arcsec r95 The 95% confidence radius 51- 58 F8.3 arcmin offset Distance from Chandra aimpoint 60- 65 F6.3 ct Ncts Net background subtracted counts 67- 72 F6.3 ct e_Ncts Standard error in Ncts 74- 78 F5.2 --- snr Signal/noise ratio; Ncts/e_Ncts 80- 84 F5.2 --- snrSc ? Soft, 0.5-2keV, band signal/noise ratio (1) 86- 90 F5.2 --- snrHc ? Hard, 2-8keV, band signal/noise ratio (1) 92- 96 F5.2 --- snrBc ? Broad, 0.5-8keV, band signal/noise ratio (1) 98-103 F6.3 ct/ks Sc ? Soft, 0.5-2keV, band count rate (1)(2) 105-109 F5.3 ct/ks e_Sc Standard error in Sc 111-116 F6.3 ct/ks Hc ? Hard, 2-8keV, band count rate (1)(2) 118-122 F5.3 ct/ks e_Hc Standard error in Hc 124-130 F7.3 ct/ks Bc ? Broad, 0.5-8keV, band count rate (1)(2) 132-136 F5.3 ct/ks e_Bc Standard error in Bc 138-142 F5.3 keV E25 The 25% percentile photon energy 144-148 F5.3 keV E50 Median (50% percentile) photon energy 150-154 F5.3 keV E75 The 75% percentile photon energy 156-160 F5.3 keV e_E25 Standard error in E25 162-166 F5.3 keV e_E50 Standard error in E50 168-172 F5.3 keV e_E75 Standard error in E75 174-179 F6.3 --- QDx Quantile X value for plotting in conventional parameter space (7) 181-185 F5.3 --- QDy Quantile Y value for plotting in conventional parameter space (7) 187 A1 --- --- [-] 188-192 F5.3 --- e_QDx ? Standard error lower bound on QDx (1) 194-198 F5.3 --- E_QDx ? Standard error upper bound on QDx (1) 200 A1 --- --- [-] 201-205 F5.3 --- e_QDy ? Standard error lower bound on QDy 207-211 F5.3 --- E_QDy Standard error upper bound on QDy 213 I1 --- gr [1/3] Quantile-based classification (3) 215-223 E9.3 mW/m2 FSc1 ? Soft, 0.5-2keV, band X-ray flux (1)(4) 225-233 E9.3 mW/m2 e_FSc1 Standard error in FSc1 235-243 E9.3 mW/m2 FHc1 ? Hard, 2-8keV, band X-ray flux (1)(4) 245-253 E9.3 mW/m2 e_FHc1 Standard error in FHc1 255-263 E9.3 mW/m2 FBc1 ? Broad, 0.5-8keV, band X-ray flux (1)(4) 265-273 E9.3 mW/m2 e_FBc1 Standard error in FBc1 275-283 E9.3 mW/m2 FSc2 ? Soft, 0.5-2keV, band X-ray flux (1)(5) 285-293 E9.3 mW/m2 e_FSc2 Standard error in FSc2 295-303 E9.3 mW/m2 FHc2 ? Hard, 2-8keV, band X-ray flux (1)(5) 305-313 E9.3 mW/m2 e_FHc2 Standard error in FHc2 315-323 E9.3 mW/m2 FBc2 ? Broad, 0.5-8keV, band X-ray flux (1)(5) 325-333 E9.3 mW/m2 e_FBc2 Standard error in FBc2 335-343 E9.3 mW/m2 FSc3 ? Soft, 0.5-2keV, band X-ray flux (1)(6) 345-353 E9.3 mW/m2 e_FSc3 Standard error in FSc3 355-363 E9.3 mW/m2 FHc3 ? Hard, 2-8keV, band X-ray flux (1)(6) 365-373 E9.3 mW/m2 e_FHc3 Standard error in FHc3 375-383 E9.3 mW/m2 FBc3 ? Broad, 0.5-8keV, band X-ray flux (1)(6) 385-393 E9.3 mW/m2 e_FBc3 Standard error in FBc3
Note (1): * Note regarding "null", i.e. blank, values: Given the diversity of source spectra in the catalog, occasionally it was not possible to compute accurate count rate, and flux values in one or two of the three energy bands (Sc, Hc, Bc). Errors in these cases are still computed from the background annulus. Some very faint sources (<2 net counts) have null values for lQDx, uQDx as the error function becomes unbounded. * Note regarding selection of f*c1, f*c2, f*c3 values: In the case of unidentified sources, the quantile-based f*c1 values should be used, f*c1 is computed using an appropriate spectral model based on the photon energy distribution. The model used for each source is indicated in the "group" column, and is defined in the paper. The f*c2 (thermal plasma) and f*c3 (powerlaw) values are appropriate when the source classification is known, e.g. from an optical counterpart. Note (2): Corrected for detector sensitivity variation. Note (3): Used for assigning spectral model in F*c1 computations. * For field DF1, the models are: group 1: NH=2.8, Γ=2.35; group 2: NH=2.5, Γ=1.42; and group 3: NH=20.0, Γ=1.52 (absorption column density in units of 1021cm-2). * For field DF2, the models are similar: group 1: NH=0.6, Γ=2.94; group 2: NH=4.9, Γ=1.38; and group 3: NH=27.0, Γ=1.91. In both fields, the algorithm identifies quantitatively similar groupings, corresponding to a very soft spectrum with typical (or sub) SMC absorption (group 1), a hard XRB-like spectrum with SMC absorption (group 2), and a heavily absorbed AGN-like spectrum (group 3). See section 2 for further details. Note (4): Computed according to one of 3 spectral models assigned by quantile-based source classification. Note (5): Computed assuming thermal plasma model. Note (6): Computed assuming power law model. Note (7): Quantile statistics defined by Hong et al. 2004ApJ...614..508H. A quantile Qx (at x%, x between 0 and 100) is defined from the energy Ex (x% of the photons have their energy below Ex) by: Qx=(Ex-El)/(Eu-El) if El=lower and Eu=upper limits of the energy. The quantities QD are: * QDx = log(Q50/(1-Q50)) = log((Em-El)/(Eu-Em)) [Em=median energy] * QDy = 3Q25/Q75 (ratio of quartiles)
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1 A1 --- f_Name [nwoxp] Pulsar status (1) 3- 9 A7 --- Name Pulsar name 11- 26 A16 --- CXOU Chandra designation (JHHMMSS.s+DDMMSS) 28- 37 F10.5 s Per ? Period 39- 46 F8.5 s e_Per ? Per uncertainty 48- 52 F5.1 % Sig ? Significance (2) 54- 57 I4 ct Ncts ? Net counts 59- 67 F9.6 deg RAdeg ? Right ascension in decimal degrees (J2000) 69- 78 F10.6 deg DEdeg ? Declination in decimal degrees (J2000) 80- 84 F5.3 arcsec r95 ? Radius of the 95% confidence region on the source position (3)
Note (1): Flag as follows: n = new pulsar in outburst w = known pulsar detected with pulsations o = known pulsar detected without pulsations x = known pulsar in the field not detected p = other periodic candidates Note (2): Significance is computed for a blind search in period range 6.5-10000s, it is not quoted for pulsars with known periods. Note (3): r95 is the radius of the 95% statistical confidence region on the source position. It does not include the 0.75" systematic aspect uncertainty.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 01-Jun-2012
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