J/ApJ/816/38 Chandra observations of 8 INTEGRAL sources (Tomsick+, 2016)
Chandra observations of eight sources discovered by INTEGRAL.
Tomsick J.A., Krivonos R., Wang Q., Bodaghee A., Chaty S., Rahoui F.,
Rodriguez J., Fornasini F.M.
<Astrophys. J., 816, 38 (2016)>
=2016ApJ...816...38T 2016ApJ...816...38T (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Gamma rays
Keywords: galaxies: active; stars: individual: (IGR J14091-6108,
IGR J18088-2741, IGR J18381-0924); white dwarfs; X-rays: stars
Abstract:
We report on 0.3-10keV observations with the Chandra X-ray Observatory
of eight hard X-ray sources discovered within 8° of the Galactic
plane by the International Gamma-ray Astrophysics Laboratory (INTEGRAL)
satellite. The short (∼5ks) Chandra observations of the IGR source
fields have yielded very likely identifications of X-ray counterparts
for three of the IGR sources: IGRJ14091-6108, IGRJ18088-2741, and
IGRJ18381-0924. The first two have very hard spectra in the Chandra
band that can be described by a power law with photon indices of
Γ=0.6±0.4 and -0.7-0.3+0.4, respectively (90% confidence
errors are given), and both have a unique near-IR counterpart
consistent with the Chandra position. IGR J14091-6108 also displays a
strong iron line and a relatively low X-ray luminosity, and we argue
that the most likely source type is a cataclysmic variable (CV),
although we do not completely rule out the possibility of a high mass
X-ray binary. IGR J18088-2741 has an optical counterpart with a
previously measured 6.84hr periodicity, which may be the binary
orbital period. We also detect five cycles of a possible 800-950s
period in the Chandra light curve, which may be the compact object
spin period. We suggest that IGR J18088-2741 is also most likely a CV.
For IGR J18381-0924, the spectrum is intrinsically softer with
Γ=1.5-0.4+0.5, and it is moderately absorbed,
NH=(4±1)x1022/cm2. There are two near-IR sources consistent with
the Chandra position, and they are both classified as galaxies, making
it likely that IGR J18381-0924 is an active galactic nucleus. For the
other five IGR sources, we provide lists of nearby Chandra sources,
which may be used along with further observations to identify the
correct counterparts, and we discuss the implications of the low
inferred Chandra count rates for these five sources.
Description:
The eight Chandra/ACIS-I observations occurred between late 2013 and
early 2015 (ObsID between 15788 and 15797).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 81 115 Chandra sources in IGR source fields
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/A+A/562/A2 : 100-month Swift catalogue of SFXTs (Romano+, 2014)
J/A+A/545/A27 : INTEGRAL/IBIS 9yr Galactic Hard X-Ray Survey (Krivonos+, 2012)
J/ApJS/186/1 : The 4th IBIS/ISGRI soft gamma-ray survey catalog (Bird+, 2010)
J/ApJ/701/811 : Chandra observations of INTEGRAL sources (Tomsick+, 2009)
J/A+A/467/585 : Sources detected by ISGRI (Bodaghee+, 2007)
J/ApJ/613/1179 : X-ray sources in Galactic Center (Muno+, 2004)
J/PAZh/30/430 : INTEGRAL X-ray source in Galactic center (Revnivtsev+, 2004)
J/A+A/411/L59 : INTEGRAL reference catalog (Ebisawa+, 2003)
http://irfu.cea.fr/Sap/IGR-Sources/ : INTEGRAL sources (IGR list)
http://cxc.cfa.harvard.edu/ : Chandra X-ray Observatory home page
http://hea.iki.rssi.ru/integral/nine-years-galactic-survey/ : INTEGRAL 9yr
Galactic survey home page
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [IGR]
5- 15 A11 --- IGR IGR field name (JHHMMm+DDMM)
17- 18 I2 --- Seq [1/29] Source number
20- 23 F4.2 arcmin Sep [0.1/10] Angular distance between the center of
the INTEGRAL error circle and the source (1)
25- 26 I2 h RAh Chandra hour of right ascension (J2000)
28- 29 I2 min RAm Minute of right ascension (J2000)
31- 35 F5.2 s RAs Second of right ascension (J2000)
37 A1 --- DE- Chandra sign of declination (J2000)
38- 39 I2 deg DEd Chandra degree of declination (J2000)
41- 42 I2 arcmin DEm Arcminute of declination (J2000)
44- 47 F4.1 arcsec DEs Arcsecond of declination (J2000)
49- 53 F5.2 arcsec PosErr [0.6/13] 90% confidence uncertainty
on position (2)
55- 59 F5.1 ct Cts [2.1/405] Chandra/ACIS-I 0.3-10keV counts (3)
61- 64 F4.1 ct E_Cts [2.9/21] Positive uncertainty on Cts
66- 69 F4.1 ct e_Cts [1.7/20] Negative uncertainty on Cts
71 A1 --- l_HR Limit flag on HR
72- 76 F5.2 --- HR [-0.7/1]? Hardness (4)
78- 81 F4.2 --- e_HR [0.06/0.8]? HR uncertainty
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Note (1): The angular distance between the center of the INTEGRAL error circle
and the source. In each case, the INTEGRAL error circle radius is
2.1' at 1σ (Krivonos et al. 2012, J/A+A/545/A27) and 4.2' at
2σ.
Note (2): The 90% confidence uncertainty on the position, including statistical
and systematic contributions.
Note (3): The number of ACIS-I counts detected (after background subtraction) in
the 0.3-10keV band. The errors are 68% confidence Poisson errors using
the analytical approximations from Gehrels (1986ApJ...303..336G 1986ApJ...303..336G).
Note (4): The hardness is given by (C2-C1)/(C2+C1), where C2 is the number of
counts in the 2-10keV band and C1 is the number of counts in the
0.3-2keV band.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 06-Apr-2016