J/MNRAS/461/3443 M31 deepest Chandra catalogue of point sources (Vulic+, 2016)
X-rays beware: the deepest Chandra catalogue of point sources in M31.
Vulic N., Gallagher S.C., Barmby P.
<Mon. Not. R. Astron. Soc., 461, 3443-3456 (2016)>
=2016MNRAS.461.3443V 2016MNRAS.461.3443V (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; X-ray sources
Keywords: catalogues - galaxies: individual: M31, NGC 224 - X-rays: binaries -
X-rays: galaxies
Abstract:
This study represents the most sensitive Chandra X-ray point source
catalogue of M31. Using 133 publicly available Chandra ACIS-I/S
observations totalling ∼1Ms, we detected 795 X-ray sources in
the bulge, north-east, and south-west fields of M31, covering an area
of ~=0.6deg2, to a limiting unabsorbed 0.5-8.0keV luminosity
of ∼1034erg/s. In the inner bulge, where exposure is
approximately constant, X-ray fluxes represent average values because
they were determined from many observations over a long period of
time. Similarly, our catalogue is more complete in the bulge fields
since monitoring allowed more transient sources to be detected. The
catalogue was cross-correlated with a previous XMM-Newton catalogue of
M31's D25 isophote consisting of 1948 X-ray sources, with only 979
within the field of view of our survey. We found 387 (49 per cent) of
our Chandra sources (352 or 44 per cent unique sources) matched to
within 5 arcsec of 352 XMM-Newton sources. Combining this result with
matching done to previous Chandra X-ray sources we detected 259. new
sources in our catalogue. We created X-ray luminosity functions (XLFs)
in the soft (0.5-2.0keV) and hard (2.0-8.0keV) bands that are the
most sensitive for any large galaxy based on our detection limits.
Completeness-corrected XLFs show a break around ~=1.3x1037erg/s,
consistent with previous work. As in past surveys, we find that the
bulge XLFs are flatter than the disc, indicating a lack of bright
high-mass X-ray binaries in the disc and an aging population of
low-mass X-ray binaries in the bulge.
Description:
We have used 133 publicly available Chandra ACIS-I/S observations
totalling ∼1Ms to create the deepest X-ray point source catalogue
of M31. We detected 795 X-ray sources within our field of view
(0.6deg2) to a limiting unabsorbed 0.5-8.0keV luminosity of
∼1034erg/s. Our 90 per cent (0.3-8.0keV) completeness limit
is 4x1035erg/s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 112 29 ACIS-S observations
table4.dat 112 102 ACIS-I observations
table5.dat 105 795 M31 source list
table6.dat 159 794 Additional M31 source properties
table8.dat 91 795 X-ray catalogue cross-matches
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See also:
J/ApJ/577/738 : M31 Chandra X-ray point sources (Kong+, 2002)
J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002)
J/ApJ/609/735 : M31 Chandra X-ray sources (Williams+, 2004)
J/ApJ/610/247 : M31 supersoft & quasi-soft X-ray sources (Di Stefano+, 2004)
J/A+A/468/49 : LMXBs in the bulge of M31 (Voss+, 2007)
J/MNRAS/402/803 : M31 globular cluster system (Peacock+, 2010)
J/A+A/534/A55 : Deep XMM-Newton Survey of M31 (Stiele+, 2011)
J/A+A/555/A65 : X-ray variability of M31 central field (Hofmann+, 2013)
J/ApJ/780/83 : X-ray binaries observed in M31 with Chandra (Barnard+, 2014)
J/ApJ/802/127 : PHAT stellar cluster survey. II. AP catalog (Johnson+, 2015)
Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ObsID ObsID
7- 16 A10 "date" Date Observation date
18- 25 F8.5 deg RAdeg Right ascension (J2000) (1)
27- 34 F8.5 deg DEdeg Declinatin (J2000) (1)
36- 39 F4.1 arcmin Dist Distance from the centre of M31
(J004244.33+411607.50)
41- 45 I5 ks Livetime Livetime (2)
47- 52 A6 --- Datamode Datamode
54- 59 A6 --- CCDs CCD chips that were on during the
observation (3)
61- 65 F5.1 deg RAngle Roll Angle
67- 68 A2 --- Reg Region of the ACIS-S in Fig. 1 (4)
70- 77 F8.5 pix Dx δx (5)
79- 86 F8.5 pix Dy δy (5)
88- 95 F8.5 deg Rot Rotation (5)
97-103 F7.5 --- Scale Scale Factor (5)
105-106 I2 --- Match Matched Sources (5)
108-112 A5 --- Cat Catalogue (5)
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Note (1): pointing of the optical axis, the RA_PNT and DEC_PNT keywords from
the level-2 events files.
Note (2): Total amount of time that CCDs actually observe a source, which
excludes the dead time (e.g. time it takes to transfer charge from the image
region to the frame store region).
Note (3): CCD chips that were on during the observation, where for ACIS-I
we used chips 0123 (I0-I3) for analysis. Also, ObsID's 1581/82 only had 2
active CCDs.
Note (4): Region of the ACIS-S as follows:
NE = north-east
B1 = left (north-east) of the bulge
B2 = bulge centre
B3 = right (south-west) of the bulge
SW = south-west
Note (5): These parameters summarize the results from matching each ObsID to a
reference astrometric catalogue (see Section 2.2 for details)
using the tool wcs_match.
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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- 3 I3 --- Seq Source sequential number
5- 22 A18 --- CXOU CXOU J name (HHMMSS.ss+DDMMSS.s)
24- 32 F9.6 deg RAdeg Right ascension (J2000)
34- 42 F9.6 deg DEdeg Declination (J2000)
44- 48 F5.2 arcmin Dist Distance from the centre of M31
(J004244.33+411607.50)
50- 52 F3.1 arcsec ePos Positional uncertainty (1)
54- 57 F4.1 arcmin theta Average off-axis angle for merged observations
59- 61 I3 --- Nobs Number of observations extracted
63- 68 A6 --- Det Detector in which the source was detected,
ACIS-I, ACIS-S, or Both
70- 71 A2 --- Reg Region for a source detected in ACIS-S or Both
73- 75 I3 ks Texp Total exposure time for merged observations
77- 84 E8.2 s.cm+2 TexpMap Totat exposure map for merged observations
86- 89 F4.1 pix Rsrc Average radius of the source extraction region
(in sky pixel = 0.492")
91- 95 F5.1 ---- SNR Photometric significance
(net counts / upper error on net counts)
(0.3-8.0keV)
97-100 F4.1 keV Emed Background-corrected median photon energy
(0.3-8.0keV)
102-105 A4 --- Match Cross-match results from Section 3.4:
active galactic nuclei (AGN) or
low-mass X-ray binary (LMXB)
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Note (1): Positional uncertainty psrt(σx2 + σy2), where the
single-axis position errors σx and σy are estimated from the
standard deviations of the PSF in the extraction region and the number of
counts extracted.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Source sequential number
5- 12 E8.4 --- pnsT Poisson probability of a detection not being
a source in total band (0.5-8.0keV)
14- 21 E8.4 --- pnsS Poisson probability of a detection not being
a source in soft band (0.5-2.0keV)
23- 30 E8.4 --- pnsH Poisson probability of a detection not being
a source in hard band (2.0-8.0keV)
32- 40 F9.2 ct NCT Net counts in total band (0.5-8.0keV)
42- 47 F6.2 ct E_NCT Error in NCT (90% upper value)
49- 54 F6.2 ct e_NCT Error in NCT (90% lower value)
56- 63 F8.2 ct NCS Net counts in soft band (0.5-2.0keV)
65- 70 F6.2 ct E_NCS Error in NCS (90% upper value)
72- 77 F6.2 ct e_NCS ?=99.99 Error in NCS (90% lower value)
79- 86 F8.2 ct NCH Net counts in hard band (2.0-8.0keV)
88- 93 F6.2 ct E_NCH Error in NCH (90% upper value)
95-100 F6.2 ct e_NCH ?=99.99 Error in NCH (90% lower value)
102-109 E8.3 mW/m2 FluxT Flux in total band (0.5-8.0keV) (1)
111-119 E9.3 mW/m2 FluxH ?=-9.99 Flux in soft band (0.5-2.0keV) (1)
121-129 E9.3 mW/m2 FluxS ?=-9.99 Flux in hard band (2.0-8.0keV) (1)
131-139 E9.3 mW/m2 FluxTSum Summed flux in total band (0.5-8.0keV)
141-149 E9.3 mW/m2 FluxSSum Summed flux in soft band (0.5-2.0keV)
151-159 E9.3 mW/m2 FluxHSum Summed flux in hard band (2.0-8.0keV)
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Note (1): Conversion factors were 5.47, 1.86, and 3.37 in units of
10-9erg/photons for the full, soft, and hard bands (to convert from photon
flux in photons/cm2/s to energy flux in erg/cm2/s). The conversion
factors account for foreground absorption using an absorbed power-law
spectrum with Γ=1.7 and NH=6.66x1020cm-2. To convert energy
fluxes to luminosity in erg/s multiply by 7.2x1049((d)/(776kpc))2.cm2.
For some sources the soft or hard band had <0 counts, and so uncertainties
could not be determined and are represented as -99.99. By extension, some
fluxes in the soft or hard band were <0 and so luminosities appear as -9.99.
Each source has a pns value <1x10-2 in at least one energy band.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Source sequential number
5- 22 A18 --- CXOU CXOU J name (HHMMSS.ss+DDMMSS.s)
24- 27 I4 --- XMMID ?=- XMM identification number
29- 36 A8 --- XMMClass XMM classification
38- 41 A4 --- ChandraCat Chandra catalog (1)
43- 48 A6 --- ChandraID Identification in Chandra catalog
50- 59 A10 --- LMXB1 Peacock et al. (2010, Cat. J/MNRAS/402/803)
globular clusters ID
61- 64 I4 --- LMXB2 ?=- Stiele et al. (2011, Cat. J/A+A/534/A55)
field ID
66- 69 I4 --- LMXB3 ?=- Stiele et al. (2011, Cat. J/A+A/534/A55)
globular clusters ID
71- 74 I4 --- AGN1 ?=- PHAT AGN matching with Andromeda project
identification number from Johnson et al.,
2015, Cat. J/ApJ/802/127,
[JSD2015] AA NNNNN in Simbad
76- 79 A4 --- AGN2 DR12 if AGN in SDSS DR12
81- 84 A4 --- AGN3 NED if AGN in NED
86- 91 A6 --- AGN4 SIMBAD if AGN in Simbad
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Note (1): Chandra catalogs as follows:
BA = Barnard et al., 2014, Cat. J/ApJ/780/83, [BGP2014] NNN in Simbad
DS02 = Di Stefano et al., 2002ApJ...570..618D 2002ApJ...570..618D, [DKG2002] NN in Simbad
DS04 = Di Stefano et al., 2004, Cat. J/ApJ/610/247, [KGP2002] AA-NN in Simbad
HO = Hofmann et al., 2013, Cat. J/A+A/555/A65, [HPH2013] NNN in Simbad
KA = Kaaret, 2002, Cat. J/ApJ/578/114, [K2002] JHHMMSS.ss+DDMMSS.s in Simbad
KO = Kong et al., 2002, Cat. J/ApJ/577/738, [KGP2002] rN-NNN in Simbad
VO = Voss & Gilfanov, 2007, Cat. J/A+A/468/49, [VG2007] NNN in Simbad
WI = Williams et al., 2004, Cat. J/ApJ/609/735
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Dec-2017