Two active X-ray transients in the Galactic Center region as seen by INTEGRAL
ATel #1005; E. Kuulkers (ESA/ESAC, Spain), S. Shaw (Southampton, UK), J. Chenevez, S. Brandt (DNSC, Denmark), T. Courvoisier (ISDC, Switzerland), A. Domingo (LAEFF/INTA, Spain), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (GSFC, USA), N. Mowlavi (ISDC, Switzerland), A. Paizis (INAF-IASF, Italy), D. Risquez (LAEFF/INTA, Spain), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 16 Feb 2007; 21:20 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Erik Kuulkers (firstname.lastname@example.org)
Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient, Variables
The first of a new series of INTEGRAL Galactic bulge monitoring observations
(ATel #438, #874) performed between UT 2007, Feb 15 18:35 and 22:17 shows
two transient X-ray sources to be active in the Galactic Center region.
One is the recently found source IGR J17453-2853 at RA, Dec (Degrees) = 266.32, -28.89,
with a 90% confidence error region of 2 arcmin (Kuulkers et al. 2007, A&A, in press,
astro-ph/0701244). The IBIS/ISGRI 20-60 keV flux was about 11 mCrab,
with a detection significance of 8. It is not detected in the JEM-X 3-10
and 10-25 keV bands with upper limits of about 5 mCrab in both bands. This source was
last seen to be active at similar flux levels between 2005, April 3 and 14. As
noted by Kuulkers et al. (2007), if the non-detection with JEM-X is due to absorption in
the line of sight, N_H should be larger than about 10^23 atoms per cm^2.
The other source is detected with JEM-X at RA, Dec (Degrees) = 266.40, -29.05, with
a 90% confidence error region of 2 arcmin. There are various known X-ray transients
within the error circle, such as Swift J174535.5-290135.6 (e.g., ATel #753, #756) or
CXOGC J174535.5-290124 (e.g., ATel #753, #892). It is detected at about 22 mCrab in 3-10
keV, with a detection significance of 14. The source is clearly variable on a 15-minute time
scale. It is not detected in the JEM-X 10-25 keV band with an upper limit of about 5 mCrab.
Follow-up observations with more position sensitive instruments are needed to pin-point
the exact origin of the transient X-ray emission.