J/ApJ/749/130 X-ray binaries in NGC 1291 with Chandra (Luo+, 2012)
Probing the X-ray binary populations of the ring galaxy NGC 1291.
Luo B., Fabbiano G., Fragos T., Kim D.-W., Belczynski K., Brassington N.J.,
Pellegrini S., Tzanavaris P., Wang J., Zezas A.
<Astrophys. J., 749, 130 (2012)>
=2012ApJ...749..130L 2012ApJ...749..130L
ADC_Keywords: Binaries, X-ray ; Galaxies, nearby ; X-ray sources
Keywords: galaxies: individual: (NGC 1291) - X-rays: galaxies -
galaxies: luminosity function, mass function - X-rays: binaries
Abstract:
We present Chandra studies of the X-ray binary (XRB) populations in
the bulge and ring regions of the ring galaxy NGC 1291. We detect 169
X-ray point sources in the galaxy, 75 in the bulge and 71 in the ring,
utilizing the four available Chandra observations totaling an
effective exposure of 179 ks. We report photometric properties of
these sources in a point-source catalog. There are ~40% of the
bulge sources and ~25% of the ring sources showing >3σ
long-term variability in their X-ray count rate. The X-ray colors
suggest that a significant fraction of the bulge (~75%) and
ring (~65%) sources are likely low-mass X-ray binaries (LMXBs).
The spectra of the nuclear source indicate that it is a low-luminosity
active galactic nucleus (AGN) with moderate obscuration; spectral
variability is observed between individual observations. We construct
0.3-8.0 keV X-ray luminosity functions (XLFs) for the bulge and ring
XRB populations, taking into account the detection incompleteness and
background AGN contamination. We reach 90% completeness limits of
~1.5x1037 and ~2.2x1037 erg/s for the bulge and
ring populations, respectively. Both XLFs can be fit with a broken
power-law model, and the shapes are consistent with those expected for
populations dominated by LMXBs. We perform detailed population
synthesis modeling of the XRB populations in NGC 1291, which suggests
that the observed combined XLF is dominated by an old LMXB population.
We compare the bulge and ring XRB populations, and argue that the ring
XRBs are associated with a younger stellar population than the bulge
sources, based on the relative overdensity of X-ray sources in the
ring, the generally harder X-ray color of the ring sources, the
overabundance of luminous sources in the combined XLF, and the flatter
shape of the ring XLF.
Description:
NGC 1291 has been observed with the S3 chip of Chandra Advanced CCD
Imaging Spectrometer (ACIS) at four epochs. The four observations
taken in 2000 Jun 27 (obsID 795), 2000 Dec 7 (obsID 2059), 2010 May 4
(obsID 11272) and 2010 May 8 (obsID 11273) have exposure times,
ranging from 37 ks to 70 ks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 203 169 Chandra point-source catalog in NGC 1291
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2013)
J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)
J/ApJ/664/458 : Spectral fit of ULX sources (Devi+, 2007)
J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)
J/ApJ/602/231 : Chandra X-ray point sources in nearby galaxies (Colbert+, 2004)
J/MNRAS/344/134 : Chandra ultraluminous X-ray sources (Humphrey+, 2003)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- XID [1/169] X-ray source index number (1)
5- 6 I2 h RAh [3] X-ray hour of Right Ascension (J2000)
8- 9 I2 min RAm [16/17] Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- [-] X-ray sign of the Declination (J2000)
18- 19 I2 deg DEd [41] X-ray degree of Declination (J2000)
21- 22 I2 arcmin DEm [0/13] Arcminute of Declination (J2000)
24- 27 F4.1 arcsec DEs Arcsecond of Declination (J2000)
29- 31 F3.1 arcmin Off [0.7/9.3] Off-Axis angle of X-ray source (2)
33- 35 F3.1 arcmin Drad Radial distance of X-ray source to galaxy nucleus
37- 42 F6.1 ct FB [4.9/3835] Full (0.3-8.0 keV) band source counts
44- 47 F4.1 ct e_FB Lower 1σ error in FB
49- 52 F4.1 ct E_FB Upper 1σ error in FB
54- 59 F6.1 ct SB [6.7/2920] Soft (0.3-2.0 keV) band source counts
61- 64 F4.1 ct e_SB ?=-1.0 Lower 1σ error in SB (3)
66- 69 F4.1 ct E_SB ?=-1.0 Upper 1σ error in SB (3)
71- 76 F6.1 ct CSB [5.1/2695] Conventional soft (0.5-2.0 keV) band
source counts
78- 81 F4.1 ct e_CSB ?=-1 Lower 1σ error in CSB (3)
83- 86 F4.1 ct E_CSB ?=-1 Upper 1σ error in CSB (3)
88- 93 F6.1 ct HB [5.6/1559] Hard (2.0-8.0 keV) band source counts
95- 98 F4.1 ct e_HB ?=-1 Lower 1σ error in HB (3)
100-103 F4.1 ct E_HB ?=-1 Upper 1σ error in HB (3)
105-110 F6.1 ct SB1 [4.9/1077] Soft (0.3-1.0keV) band #1 source counts
112-115 F4.1 ct e_SB1 ?=-1 Lower 1σ error in SB1 (3)
117-120 F4.1 ct E_SB1 ?=-1 Upper 1σ error in SB1 (3)
122-127 F6.1 ct SB2 [5.1/1789] Soft (1.0-2.0keV) band #2 source counts
129-132 F4.1 ct e_SB2 ?=-1 Lower 1σ error in SB2 (3)
134-137 F4.1 ct E_SB2 ?=-1 Upper 1σ error in SB2 (3)
139-146 E8.3 s Texp [9300/172000] Full band effective exposure time (4)
148-152 F5.2 --- SC [-1.27/0.98] Soft color ((M-S)/T) (5)
154-157 F4.2 --- e_SC ?=-1 Lower 1σ error in SC
159-162 F4.2 --- E_SC ?=-1 Upper 1σ error in SC
164-168 F5.2 --- HC [-0.92/1.05] Hard color ((H-M)/T) (5)
170-173 F4.2 --- e_HC ?=-1 Lower 1σ error in HC
175-178 F4.2 --- E_HC ?=-1 Upper 1σ error in HC
180-183 F4.2 --- Gamma [0.6/4.3] Photon index Γ (6)
185-192 E8.3 10-7W LX Observed full-band X-ray luminosity; erg/s
194-197 F4.1 --- Var [0/45.1]?=-1 Full-band flux variability statistical
significance (7)
199-203 A5 --- Reg Region flag (Bulge, Ring or Other) (8)
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Note (1): Listed in order of increasing right ascension;
<[LFF2012] NNN> in Simbad.
Note (2): This is the distance between the source position and the average
aim point (see Section 2).
Note (3): A -1.0 value indicates upper limits.
Note (4): Determined from the exposure map, which has been corrected for
vignetting and quantum-efficiency degradation.
Note (5): The X-ray colors are defined as HC=(H-M)/T and SC=(M-S)/T, where
S , M , H , and T are the count rates in the 0.3-1.0 keV,
1.0-2.0 keV, 2.0-8.0 keV, and 0.3-8.0 keV bands, respectively.
Note (6): Derived from spectral fitting, or set to Γ = 1.7 if the
number of full-band counts is smaller than 30.
Note (7): See Section 4.3 for details. It is set to -1.0 if the flux
variability is not available.
Note (8): The flag is "Bulge" if the source is located in the bulge, "Ring" if
the source is in the ring, or "Other" if the source is neither in the
bulge nor in the ring.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Nov-2013