Swift/XRT monitoring of the long outburst of the Very Faint X-ray Transient XMMU J174716.1-281048
ATel #3471; Melania Del Santo (INAF/IASF-Roma), Patrizia Romano (INAF/IASF-Palermo), Lara Sidoli (INAF/IASF-Milano)
on 4 Jul 2011; 14:43 UT
Credential Certification: Melania Del Santo (melania.delsanto@iasf-roma.inaf.it)
Subjects: X-ray, Binary, Neutron Star, Transient
The Very Faint X-ray Transient (VFXT) XMMU J174716.1-281048,
discovered in 2003 by XMM-Newton (ATel #147; Sidoli et al., 2006, A&A 456, 287),
has been unveiled by INTEGRAL as type I X-ray burster
(ATel #970; #972; Del Santo et al., 2007, A&A 468, L17)
lying in the Galactic Centre region (ATel #1207).
XMMU J174716.1-281048 is the first VFXT classified as ``quasi persistent",
due to the fact that it appears to have been continuously active
since its discovery (Del Santo et al., 2007; ATel #1078).
The level of its X-ray emission has been regularly monitored
by Swift since May 2007 (ATel #1078, #1174, #1496, #2050, #2624).
On 2010 August 13 Swift/BAT was triggered by an intermediate type-I burst
lasting 3 h from this source (Degenaar et al. 2011, astro-ph/1103.4153).
A new ToO with Swift/XRT was performed on 2011-06-19 04:14:17 UT to
10:55:55 UT (4.5 ks net exposure), and on 2011-06-23 07:57:21 UT to
16:06:56 UT (2.0 ks net exposure). The source was found still in
outburst with a mean 0.2-10 keV count rate of (2.8+/-0.3)E-02 counts/s.
The XRT spectrum can be fitted with an absorbed power law
with a photon index of 2.4 (-1.0,+1.0) and a column density,
Nh, of 8 (-3, +4) E22 cm^-2 (cstat=155.1, dof=139).
The 2-10 keV unabsorbed flux of 4E-12 erg/cm2/s translates into
a luminosity of 4.5E34 erg/s (at 8 kpc).
The long-term light curve of XMMU J174716.1-281048 can be found at http://www.ifc.inaf.it/~romano/ATels/XMMUJ174716.1_281048_xrt.html
We would like to thank the Swift Team for making these observations
possible, in particular N. Gehrels, the duty scientists as well as
the science planners.
