J/A+A/555/A65 X-ray variability of M31 central field (Hofmann+, 2013)
X-ray source variability study of the M 31 central field using Chandra HRC-I.
Hofmann F., Pietsch W., Henze M., Haberl F., Strum R., Della Valle M.,
Hartmann D.H., Hatzidimitriou D.
<Astron. Astrophys. 555, A65 (2013)>
=2013A&A...555A..65H 2013A&A...555A..65H
ADC_Keywords: Binaries, X-ray ; X-ray sources
Keywords: galaxies: individual: M 31 - X-rays: galaxies - X-rays: binaries -
galaxies: stellar content - catalogs
Abstract:
The central field of the Andromeda galaxy (M31) was monitored from
2006 to 2012 using the Chandra HRC-I detector (about 0.1-10keV energy
range) with the main aim of detecting X-rays from optical novae. We
present a systematic analysis of all X-ray sources found in the 41
nova monitoring observations, along with 23 M31 central field HRC-I
observations available from the Chandra data archive starting in
December 1999. Based on these observations, we studied the X-ray
long-term variability of the source population and especially of X-ray
binaries in M31. We created a catalogue of sources detected in the 64
available observations that adds up to a total exposure time of about
1Ms. To study the variability, we developed a processing pipeline to
derive long-term Chandra HRC-I light curves for each source over the
13 years of observations. We also searched for extended X-ray sources
in the merged images. We present a point-source catalogue containing
318 X-ray sources with detailed long-term variability information, 28
of which are published for the first time. The spatial and temporal
resolution of the catalogue allows us to classify 115 X-ray binary
candidates showing high X-ray variability or even outbursts, as well
as 14 globular cluster X-ray binary candidates showing no significant
variability. The analysis may suggest that outburst sources are less
frequent in globular clusters than in the field of M31. We detected
seven supernova remnants, one of which is a new candidate, and also
resolved the first X-rays from a known radio supernova remnant. In
addition to 33 known optical nova/X-ray source correlations, we
discovered one previously unknown super-soft X-ray outburst and
several new nova candidates. The catalogue contains a large sample of
detailed long-term X-ray light curves in the M31 central field, which
helps in understanding the X-ray population of our neighbouring spiral
galaxy M31.
Description:
For all Chandra HRC-I observations a source catalogue was created and
the energy flux of each source in each observation was derived. Fluxes
were calculated assuming a generic power law spectrum and Galactic
foreground absorption for each source.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 396 318 Source catalogue with general source information
xcorr.dat 101 1735 X-ray correlations
table1.fit 2880 93 FITS version of table 1
table2.dat 62 19716 Light curve table containing flux and errors
table2.fit 2880 246 *FITS version of table 2
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Note on table2.fit: The FITS table presents, for each row corresponding to
one observation, 318*3 columns of fluxes providing, for each of the
318 sources, its flux, 1-σ up/low errors. When the detection
significance was below 1-σ, flux is zero and the flux_up column
provides a 3-σ upper limit for the source. When flux_up and
flux_lo are zero, the source was outside the field of view of the
observation.
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- SRCID [1/318] Source identification number
5- 13 F9.5 deg RAdeg Right ascension (J2000)
15- 23 F9.5 deg DEdeg Declination (J2000)
25- 33 F9.5 arcsec ePos Positional error (1)
35- 46 E12.6 ct ctN Net counts
48- 56 F9.5 ct e_ctN Error of net counts
58- 69 E12.6 ct ctBkg Net background counts
71- 78 F8.6 ct/s CRN Net count rate
80- 91 E12.6 ct/s e_CRN Error of net count rate
93-100 F8.6 ct/s CRBkg Background count rate
102-113 E12.6 ct/s e_CRBkg Error of background count rate
115-126 E12.6 s ExpTime Exposure time
128-139 E12.6 --- Signi Highest detection significance
141 I1 --- Res Detection-image resolution (binning) (2)
143-151 E9.2 mW/m2 Flux Flux in 0.2-10keV band, in erg/s/cm2 (3)
153-161 E9.2 mW/m2 e_Flux Flux error
163-171 E9.2 10-7W Lum Luminosity, assuming a distance of 780kpc
173-181 E9.2 10-7W e_Lum Luminosity error
183-191 E9.2 arcsec DistNN Distance to nearest neighbour
193-201 E9.2 --- svar Source variability parameter
(Fmax-Fmin)/sqrt(σmax2+σmin2)
203-211 E9.2 --- fvar Highest source flux ratio (Fmax/Fmin)
213-220 F8.6 --- ndet [0/1] Number of detections (8)
222-231 F10.6 --- ssvar Highest svar between observations
233-244 E12.6 mW/m2 Fmax Maximum flux
246-257 E12.6 mW/m2 e_Fmax Error of maximum flux
259-270 E12.6 mW/m2 Fmin Minimum flux
272-283 E12.6 mW/m2 e_Fmin Error of minimum flux
285-286 A2 --- lcC [HV OB] Light curve classification:
HV (highly variable) or OB (outburst)
288-315 A28 --- nova Nova name(s) (4)
317-328 A12 --- glc ? Globular-cluster name (5)
330-337 A8 --- Class Source classification (6)
339-396 A58 --- Com Comments and references (7)
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Note (1): 3 x (1-σ statistical error plus systematic errors)
Note (2): Detection-image resolution as:
1 = 1x1 binning
2 = 2x2 binning
3 = 4x4 binning
4 = 8x8 binning
5 = 16x16 binning
Note (3): 0.2-10keV flux calculated for a power-law spectrum with a photon
index of 1.7 and Galactic foreground absorption (column density of
NH=6.6x1020cm-2).
Note (4): Nova identifier (M31N YYYY-MMa) gives year (YYYY) and month (MM)
of outburst plus a letter to distinguish multiple novae per month.
Note (5): Globular cluster name followed by quality flag (see Revised Bologna
Catalog of Globular Clusters: Galleti et al., 2007, Cat. J/A+A/471/127)
Note (6): Classes (candidates are marked with <>) are:
XRB = X-ray binary
GlC = globular cluster
SSS = super-soft source
nova = nova
SNR = supernova remnant
AGN = active galactic nucleus
fgStar = foreground star
Note (7): Abbreviations and Codes used:
TPC2006 = Trudolyubov et al., 2006ApJ...645..277T 2006ApJ...645..277T
HHP2009 = Haberl et al., 2009ATel.2262....1H 2009ATel.2262....1H
GGS2007 = Galache et al., 2007ATel.1171....1G 2007ATel.1171....1G
HPG2006 = Haberl et al., 2006ATel..881....1H 2006ATel..881....1H
BGG2012 = Barnard et al., 2012ApJ...756...32B 2012ApJ...756...32B
B90 = Braun, 1990ApJS...72..761B 1990ApJS...72..761B
HPH2010 = Henze et al., 2010A&A...523A..89H 2010A&A...523A..89H
GGT2009 = Galache et al., 2009ATel.1978....1G 2009ATel.1978....1G
KGG2009 = Kong et al., 2009ATel.2074....1K 2009ATel.2074....1K
HHP2012 = Kong et al., 2012ATel.4164....1H 2012ATel.4164....1H
HPH2012a = Henze et al., 2012ATel.3890....1H 2012ATel.3890....1H
HPH2012b = Henze et al., 2012ATel.3921....1H 2012ATel.3921....1H
HPH2012c = Henze et al., 2013A&A...549A.120H 2013A&A...549A.120H
GGT2008 = Galache et al., 2008ATel.1698....1G 2008ATel.1698....1G
TP2008 = Trudolyubov & Priedhorsky, 2008ApJ...676.1218T 2008ApJ...676.1218T
HPH2009 = Henze et al., 2009ATel.2356....1H 2009ATel.2356....1H
KGM2001 = Kong et al., 2001ATel...76....1K 2001ATel...76....1K
PBG2008 = Pietsch et al., 2008ATel.1674....1P 2008ATel.1674....1P
HHP2007 = Harbel et al., 2007ATel.1296....1H 2007ATel.1296....1H
TBP2001 = Trudolyubov et al., 2001ApJ...563L.119T 2001ApJ...563L.119T
TBP2002 = Trudolyubov et al., 2002ApJ...581L..27T 2002ApJ...581L..27T
PFH2008 = Pietsch et al., 2008ATel.1647....1P 2008ATel.1647....1P
HPH2009 = Henze et al., 2009A&A...500..769H 2009A&A...500..769H
WGM2005 = Williams et al., 2005ApJ...632.1086W 2005ApJ...632.1086W
BK2009 = Barnard & Kolb, 2009MNRAS.397L..92B 2009MNRAS.397L..92B
BKO2004 = Barnard et al., 2004A&A...423..147B 2004A&A...423..147B
PHH2012 = Pietsch et al., 2010ATel.3038....1P 2010ATel.3038....1P
no lc = no light curve available
AP = activity period
SOB = short outburst
rec = recurrent
XT[SRCID] = cross-talk with SRCID
LOB = long outburst
ULX = ultra-luminous X-ray source
M31* = nucleus of M 31
radio B90 = correlation with radio source in B90 catalogue
Note (8): ndet is the fraction of the number of data points in the light
curve having a count>1-σ.
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Byte-by-byte Description of file: xcorr.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- SRCID Source identification number in the catalogue
5- 13 A9 --- Cat X-ray correlations Catalogue (1)
15 A1 --- --- [:]
17-101 A85 --- XID Identification and description in "Cat" (1)
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Note (1): The correlation contains the Catalogue "Cat", identification and
description in the Catalogue. References and column name in reference
catalogues are:
KGP2002 = Kong et al., 2002 Cat. J/ApJ/577/38, Notes
Ka2002 = Kaaret, 2002, Cat. J/ApJ/578/114, CXOM31
PFH2005 = Pietsch et al., 2005, Cat. J/A+A/434/483, Class
SHL2001 = Supper et al., 2001, Cat. J/A+A/373/63, n_SII
SHP97 = Supper et al., 1997, Cat. J/A+A/317/328, n_ROSAT
SPH2008 = Stiele et al., 2008, Cat. J/A+A/480/599, Class
SPH2011 = Stiele et al., 2011, Cat. J/A+A/534/A55, Class
VG2007 = Voss & Gilfanov, 2007, Cat. J/A+A/468/49, Type
WGK2004 = Williams et al., 2004, Cat. J/ApJ/609/735, Type
WNG2006 = Williams et al., 2006, Cat. J/ApJ/643/356, F
HPH2011 = Henze et al., 2011, Cat. J/A+A/533/A52, M31N
PHS2007 = Pietsch et al., 2007, Cat. J/A+A/465/375, M31N
CSC = Evans et al., 2010ApJS..189...37E 2010ApJS..189...37E (Cat. IX/45), msid
D2002 = Di Stefano et al., 2002ApJ...570..618D 2002ApJ...570..618D, opt_ident
DKG2004 = Di Stefano et al., 2004, Cat. J/ApJ/610/247, category
O2006 = Orio, 2006ApJ...643..844O 2006ApJ...643..844O, type
OBT2001 = Osborne et al., 2001A&A...378..800O 2001A&A...378..800O, Comments
SBK2009 = Shaw Greening et al., 2009, Cat. J/A&A...495..733S, type
TF91 = Trinchieri & Fabbiano, 1991ApJ...382...82T 1991ApJ...382...82T, INDEX
TP2004 = Trudolyubov & Priedhorsky, 2004ApJ...616..821T 2004ApJ...616..821T, optical_id
TP2006 = Trudolyubov et al., 2006ApJ...645..277T 2006ApJ...645..277T, class
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
-------------------------------------------------------------------------------
1- 3 I3 --- SRCID [1/318] Sequential number
5- 9 I5 --- ObsID [267/13281] HRC-I observation identifier
11- 20 A10 "YYYY-MM-DD" Date Date of the observation
22- 32 F11.5 d MJD Modified Julian Date
34 A1 --- l_Flux [<] when 3-σ upper limit in Flux for
sources with detection-significance <1σ
35- 42 E8.3 mW/m2 Flux ? Flux (1)
45- 52 E8.3 mW/m2 B_Flux ? Upper value of flux with 1σ error (1)
55- 62 E8.3 mW/m2 b_Flux ? Lower value of flux with 1σ error (1)
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Note (1): When no values, the source was outside the field of view of the
observation.
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Acknowledgements:
Florian Hofmann, fhofmann(at)mpe.mpg.de
History:
* 21-May-2013: FITS files
* 12-Jan-2014: reformatted files table2.dat and wcorr.dat
(End) Florian Hofmann [MPE,Germany], Patricia Vannier [CDS] 21-May-2013