J/ApJS/224/40 Catalog of Chandra ACIS point like sources (Wang+, 2016)
CHANDRA ACIS survey of X-ray point sources: the source catalog.
Wang S., Liu J., Qiu Y., Bai Y., Yang H., Guo J., Zhang P.
<Astrophys. J. Suppl. Ser., 224, 40-40 (2016)>
=2016ApJS..224...40W 2016ApJS..224...40W (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Galaxies, nearby
Keywords: catalogs; X-rays: general
Abstract:
The Chandra archival data is a valuable resource for various studies
on different X-ray astronomy topics. In this paper, we utilize this
wealth of information and present a uniformly processed data set,
which can be used to address a wide range of scientific questions. The
data analysis procedures are applied to 10029 Advanced CCD Imaging
Spectrometer observations, which produces 363530 source detections
belonging to 217828 distinct X-ray sources. This number is twice the
size of the Chandra Source Catalog (Version 1.1). The catalogs in this
paper provide abundant estimates of the detected X-ray source
properties, including source positions, counts, colors, fluxes,
luminosities, variability statistics, etc. Cross-correlation of these
objects with galaxies shows that 17828 sources are located within the
D25 isophotes of 1110 galaxies, and 7504 sources are located between
the D25 and 2D25 isophotes of 910 galaxies. Contamination analysis
with the log N-log S relation indicates that 51.3% of objects within
2D25 isophotes are truly relevant to galaxies, and the "net" source
fraction increases to 58.9%, 67.3%, and 69.1% for sources with
luminosities above 1037, 1038, and 1039erg/s, respectively.
Among the possible scientific uses of this catalog, we discuss the
possibility of studying intra-observation variability,
inter-observation variability, and supersoft sources (SSSs). About
17092 detected sources above 10 counts are classified as variable in
individual observation with the Kolmogorov-Smirnov (K-S) criterion
(PK-S<0.01). There are 99647 sources observed more than once and
11843 sources observed 10 times or more, offering us a wealth of data
with which to explore the long-term variability. There are 1638
individual objects (∼2350 detections) classified as SSSs. As a quite
interesting subclass, detailed studies on X-ray spectra and optical
spectroscopic follow-up are needed to categorize these SSSs and
pinpoint their properties. In addition, this survey can enable a wide
range of statistical studies, such as X-ray activity in different
types of stars, X-ray luminosity functions in different types of
galaxies, and multi-wavelength identification and classification of
different X-ray populations.
Description:
The ACIS observations were downloaded from the Chandra Data Archive on
2014 December 4, yielding 10047 ACIS observations. Eighteen
observations with PI as "Calibration" or Exposure as zero were
excluded. Finally, there are 10029 ACIS observations containing 4146
ACIS-I observations and 5883 ACIS-S observations in our sample. The
exposure times for the selected observations cover a range from 50s to
190ks, with a total of 221851ks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 223 766496 Detected X-ray point sources in the Chandra ACIS
survey
table4.dat 298 766496 Counts in different bands for detected X-ray
point sources in the Chandra ACIS survey
table5.dat 177 218789 Independent X-ray sources and their average
properties in multiple observations
gal.dat 13 1260 List of galaxy names in table 5;
table added by CDS
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
IX/45 : The Chandra Source Catalog, Release 1.1 (Evans+ 2012)
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)
J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)
J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)
J/AJ/128/1501 : CLASXS: X-ray catalog (Yang+, 2004)
J/ApJS/150/19 : ChaMP. I. First X-ray source catalog (Kim+, 2004)
J/AJ/126/539 : The Chandra Deep Fields North and South (Alexander+, 2003)
J/A+A/329/482 : ROSAT Deep Survey in the Lockman Hole (Hasinger+, 1998)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Group [1/4953] Group Number
6- 11 A6 --- --- [CXOGSG]
13- 28 A16 --- CXOGSG Source name (JHHMMSS.s+DDMMSS)
30- 42 A13 --- Det Source name in individual observations (G1)
44- 47 F4.2 --- Split ? Split fraction (G2)
49- 56 F8.1 s Exp [58/192363]? Source exposure time after
deadtime correction
58- 66 F9.3 d MJD ? Modified Julian Date for the beginning
point of the observation
68- 71 I4 pix Dedge ? Distance from the source center to the
nearest chip edge.
73- 76 I4 arcsec OAA Off-axis angle, arcseconds
78- 82 F5.3 --- VigF [0.001/1.3]? Vignetting factor (3)
84- 88 F5.2 arcsec e_RAdeg [0/87]? Statistical positional error,
Right Ascension
90- 93 F4.2 arcsec e_DEdeg [0/3]? Statistical positional error,
Declination
95- 99 F5.2 arcsec PosErr [1/36]? Source positional uncertainties (4)
101-106 F6.1 --- sig [-354/1997]? Detection significance (5)
108-115 F8.1 ct Cts [0.1/136000]? Background-subtracted photon
counts (6)
117-122 F6.1 ct e_Cts [1/3306]? Uncertainty in Cts
124-131 F8.1 ct bkgd ? Background counts within the source region
133-139 F7.2 --- CMS [-742/241]? X-ray color CMS=(M-S)/(H+M+S) (7)
141-144 F4.2 --- e_CMS [0/1]? Uncertainty in CMS
146-153 F8.2 --- CHM [-7911/269]? X-ray color CHM=(H-M)/(H+M+S) (7)
155-158 F4.2 --- e_CHM [0/1]? Uncertainty in CHM
160-168 A9 --- FX Source flux (8)
170-177 A8 --- PK-S K-S probability that a source is constant
during an observation
179-182 A4 --- SQH Phase classification for the source (9)
184-198 A15 --- sig/PFFT Period significance and the most possible
period (in second) from FFT algorithm
200-202 I3 --- Nae [2/13]? Number of possible afterglow events
for sources with total events less than 100
205-213 F9.5 deg RAdeg ? Right Ascension in decimal degrees (J2000)
215-223 F9.5 deg DEdeg ? Declination in decimal degrees (J2000)
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Note (3): Vignetting factor calculated from the exposure map being the ratio
between the local and the maximum map value.
Note (4): Source positional uncertainties calculated from the scheme of
Kim et al. (2007, J/ApJS/169/401)
Note (5): Detection significance from wavdetect. If the source is not detected
in an observation, it is computed as (net count)/(count error)
(Section 3.2) and prefixed with a negative sign.
Note (6): Background-subtracted photon counts from wavdetect, or calculated
from a circular region equal to the PSF enclosing 95% of the energy at
1.5 keV for the upper limit.
Note (7): S/M/H represents background-subtracted counts in soft (0.3-1keV),
medium (1-2keV), and hard (2-8keV) bands.
Note (8): Source flux calculated from the vignetting corrected count rate
in 0.3-8keV, assuming Galactic nH absorption and a power law of 1.7.
Note (9): Phase classification for the source during an observation as follows:
SSS = supersoft sources (2355 sources);
QSS = quasi-soft sources (23820 sources);
hard = hard sources (259174 sources);
dim = less than 10 counts (78161 sources).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Group [1/4953] Group Number
6- 12 A7 --- --- [CXOGSG-]
13- 28 A16 --- CXOGSG Source name (JHHMMSS.s+DDMMSS)
30- 42 A13 --- Det Source name in individual observations (G1)
44- 47 F4.2 --- Split ? Split fraction (G2)
49- 57 F9.2 ct Ct(0.1-1.1) ? Source net counts, 0.1-1.1 keV (3)
59- 64 F6.2 ct e_Ct(0.1-1.1) ? Uncertainty in Ct(0.1-1.1) (3)
66- 74 F9.2 ct Ct(0.3-1.1) ? Source net counts, 0.3-1.1 keV (3)
76- 81 F6.2 ct e_Ct(0.3-1.1) ? Uncertainty in Ct(0.3-1.1) (3)
83- 91 F9.2 ct Ct(0.3-1) ? Source net counts, 0.3-1 keV (3)
93- 98 F6.2 ct e_Ct(0.3-1) ? Uncertainty in Ct(0.3-1) (3)
100-107 F8.2 ct Ct(0.1-0.5) ? Source net counts, 0.1-0.5keV (3)
109-114 F6.2 ct e_Ct(0.1-0.5) ? Uncertainty in Ct(0.1-0.5) (3)
116-123 F8.2 ct Ct(0.3-0.5) [-265/11865]? Source net counts,
0.3-0.5keV (3)
125-130 F6.2 ct e_Ct(0.3-0.5) [1/113]? Uncertainty in Ct(0.3-0.5) (3)
132-139 F8.2 ct Ct(0.1-0.8) ? Source net counts, 0.1-0.8 keV (3)
141-146 F6.2 ct e_Ct(0.1-0.8) ? Uncertainty in Ct(0.1-0.8) (3)
148-155 F8.2 ct Ct(0.3-0.8) ? Source net counts, 0.3-0.8 keV (3)
157-162 F6.2 ct e_Ct(0.3-0.8) ? Uncertainty in Ct(0.3-0.8) (3)
164-172 F9.2 ct Ct(1-2) ? Source net counts, 1-2 keV (3)
174-179 F6.2 ct e_Ct(1-2) ? Uncertainty in Ct(1-2) (3)
181-189 F9.2 ct Ct(1.1-2) ? Source net counts, 1.1-2 keV (3)
191-196 F6.2 ct e_Ct(1.1-2) ? Uncertainty in Ct(1.1-2) (3)
198-206 F9.2 ct Ct(0.5-2.4) ? Source net counts, 0.5-2.4 keV (3)
208-213 F6.2 ct e_Ct(0.5-2.4) ? Uncertainty in Ct(0.5-2.4) (3)
215-223 F9.2 ct Ct(0.5-2) ? Source net counts, 0.5-2 keV (3)
225-230 F6.2 ct e_Ct(0.5-2) ? Uncertainty in Ct(0.5-2) (3)
232-240 F9.2 ct Ct(0.8-2) ? Source net counts, 0.8-2 keV (3)
242-247 F6.2 ct e_Ct(0.8-2) ? Uncertainty in Ct(0.8-2) (3)
249-257 F9.2 ct Ct(2-8) ? Source net counts, 2-8 keV (3)
259-264 F6.2 ct e_Ct(2-8) ? Uncertainty in Ct(2-8) (3)
266-274 F9.2 ct Ct(0.1-8) ? Source net counts, 0.1-8 keV (3)
276-281 F6.2 ct e_Ct(0.1-8) ? Uncertainty in Ct(0.1-8) (3)
283-291 F9.2 ct Ct(0.3-8) ? Source net counts, 0.3-8 keV (3)
293-298 F6.2 ct e_Ct(0.3-8) ? Uncertainty in Ct(0.3-8) (3)
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Note (3): Source net counts is computed from aperture photometry with the
wavdetect 3σ region.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Group [1/4953] Group Number
6- 11 A6 --- --- [CXOGSG]
13- 28 A16 --- CXOGSG Source name (JHHMMSS.s+DDMMSS)
29- 29 A1 --- f_CXOGSG [*] Projected overlapping galaxies flag (1)
31- 35 F5.2 arcsec ePos [1/36]? Statistical positional error after
Kim et al. (2007, J/ApJS/169/401)
37- 50 A14 --- GName Galaxy source names numbered sequentially
based on maximum detection significance
52- 58 F7.3 arcmin Sep [0.002/641]? Galaxy source nuclear separation
60- 63 F4.2 --- SepR [0/3]? Galaxy source nuclear separation
in units of the galaxy's elliptical radius
65- 72 F8.4 Mpc Dist [-0.2/303.5] Distance in Mpc for the
X-ray source
74- 80 A7 --- O/D Observed/Detected statistics
82- 90 A9 10-7W Lum Maximum luminosity among detections, erg/s
92- 99 A8 mW/m2 Flux Average flux among detections, erg/cm2/s
101-108 F8.1 --- Fmax/Fmin [1/303734] Fmax/Fmin ratio (2)
110-118 F9.4 --- E_Fmax/Fmin [0.009/5200]? Upper uncertainty on Fmax/Fmin
120-128 F9.4 --- e_Fmax/Fmin ? Lower uncertainty on Fmax/Fmin
130-137 F8.3 --- Sig [0.01/1997]? Maximum detection significance
139-148 F10.3 ct MaxCts [0.05/136146]? Maximum photon counts among
the detections
150-162 A13 --- Phases Statistics for SSS/QSS/hard/dim phases (3)
164-167 A4 --- VarKS Statistics for variability during individual
observations using the K-S criterion (4)
169-177 A9 --- Class Source identification (5)
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Note (1): Sources marked with "*" are projected within two or more galaxies
with overlapping domains. This implies multiple GName for
one CXOGSG name.
Note (2): Fmax/Fmin ratio as an extreme variability indicator, with Fmax as the
maximum 0.3-8 keV flux from all detections, and Fmin as the minimum flux
from all detections or upper limits. The ratio is set to one without an
error if Fmax equals to Fmin.
Note (3): Statistics for SSS/QSS/hard/dim phases. For example, s1 means SSS in
one observation, q2 means QSS in two observations, h3 means hard in three
observations, and d4 means dim (below 10 counts) in four observations --
s# = number of observations in SSS phase;
q# = number of observations in QSS phase
h# = number of observations in hard phase;
d# = number of observations in dim (< 10 cts) phase.
Note (4): Statistics for variability during individual observations using the
K-S criterion. For example, v:2 means the source is regarded as variable
(i.e., PK-S < 0.01, counts > 10) in two observations.
Note (5): Source identification as follows:
ULX = Ultraluminous X-ray sources with observed LX (0.3-8keV) in excess
of 2*10+39erg/s;
EULX = Maximum LX≥1040erg/s;
1ULX = ULX inside D25 isophotes;
1EULX = EULX inside D25 isophotes;
2ULX = ULX between D25 and 2D25 isophotes, without nuclear sources excluded;
2EULX = EULX between D25 and 2D25 isophotes, without nuclear sources excluded;
ULS = Ultraluminous supersoft sources with at least one SSS phase in
which LX (0.3-8keV) exceeds 2*10+38erg/s (Liu 2011, J/ApJS/192/10).
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Byte-by-byte Description of file: gal.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Gal Galaxy name
10- 13 I4 --- Nx Number of sources for this galaxy in table 5;
column added by CDS
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Global notes:
Note (G1): Source name in individual observations in form of NNNN.sN.NN, where
"NNNN" is the Chandra ObsId, "sN" is the CCD chip, and "NN" is the source
number from wavdetect. If the source is observed but not detected in an
observation, "NN" is marked as "u" and no coordinates are given.
"m0" is not explained in the paper.
Note (G2): The split fraction, which is less than unity if a source is a split
part of a merged source in an observation as described in Section 3.1, and
the true counts and flux in this observation can be derived from the
listed counts and flux multiplied by this fraction.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Jul-2016