[ Previous | Next | ADS ]

Swift/XRT detection of X-ray emission from a symbiotic binary and another source in the field of IGR J17197-3010

ATel #3960; G. J. M. Luna (ICATE, Argentina), J. L. Sokoloski (Columbia U.), K. Mukai (NASA/GSFC), N. Nunez (ICATE, Argentina)
on 9 Mar 2012; 19:11 UT
Credential Certification: Gerardo Juan Manuel Luna (gluna@cfa.harvard.edu)

Subjects: X-ray, A Comment

We report the Swift/XRT detection of two sources in the field of IGR J17197-3010. Swift observed the field of IGR J17197-3010 for a total of 10394 s between 2010-03-05 and 2012-02-12, detecting the first source at a 6.4 sigma level with a count rate of 0.0087+/-0.0014 counts/s at the coordinates alpha = 17h 19m 51.7s and delta = -30d 02' 0.6" (with an error radius of 4.3"). These XRT coordinates are consistent with the position of a symbiotic star at alpha = 17h 19m 51.83s and delta =-30d 02m 0.3s that Massetti et al. (2012) proposed as a "tentative, albeit likely, counterpart" to IGR J17197-3010. The position of the symbiotic star, however, is approximately 9 arcmin away from the nominal position of IGR J17197-3010, which was detected by INTEGRAL at a 0.35 mCrab flux level at alpha=17h 19m 43.2s, delta=-30d 10' 48" (with a 68% confidence error radius of 2.1 arcmin; Krivonos et al., 2007, A &A, 475, 775). Given the agreement between the position of the XRT source and the optical coordinates of the symbiotic star, the disagreement between these coordinates and those of the INTEGRAL source, and the low X-ray flux, we tentatively conclude that the symbiotic star and IGR J17197-3010 are not related. The XRT spectrum of the symbiotic star is rather hard for a symbiotic, extending up to ~5 keV. A preliminary fit suggests that the spectrum can be modeled with an absorbed (nH > 1.6e22 cm^-2) two-temperature plasma (kT_1=3_{-2}^{+13} keV and kT_2=0.3_{-0.1}^{+0.1}keV). The unabsorbed flux in the 0.3-10.0 keV band is around 2.7e-13 erg/s/cm^2, and at a distance of 6.3 kpc (Masetti et al. 2012), the X-ray luminosity is about 1.3e33 erg/s. Swift/XRT also detected a second X-ray source in the field of IGR J17197-3010, at a position alpha = 17h 19m 48.52s and delta = -30d 17' 25.87" (with an error radius of 4.1"). This second XRT source is 6.8 arcmin from the INTEGRAL position of IGR J17197-3010. The second XRT source is detected at an 8.5 sigma level with a count rate of 0.0150+/- 0.0018 counts/s. The spectrum is well described by an absorbed (nH=0.18_{-0.10}^{+0.13} 10^22 cm^-2) plasma with a temperature kT=2.9_ {-0.8}^{+1.4} keV. The unabsorbed flux is about 5.7e-13 erg/s/cm^2. The closest source (3.1 arcmin away) listed by SIMBAD is IGR J17198-3020 (Bird et al. 2010, ApJS, 186,1), which is classified as a transient soft gamma-ray source. We gratefully acknowledge the effort of the entire Swift team for the execution of our ToO request.