XMM-Newton observation of the symbiotic recurrent nova V745 Sco in quiescence
ATel #5881; G. J. M. Luna (IAFE/Argentina), I. Pillitteri (INAF, Italy), K. Mukai (NASA & UMBC), J. L. Sokoloski (Columbia Univ., USA)
on 12 Feb 2014; 12:38 UT
Credential Certification: Gerardo Juan Manuel Luna (gluna@cfa.harvard.edu)
Subjects: Ultra-Violet, X-ray, Nova
We report the detection of the recurrent nova V745 Sco in X-rays and UV with XMM-Newton in an observation taken in 03/01/2010 (PI: J. Sokoloski, ObsID 0604980201), during quiescence. We searched for X-ray emission using an algorithm based on wavelet convolution for the EPIC images (see Damiani et al. 1997 for details). V745 Sco is detected at the coordinates alpha= 17h 55m 22.39s and delta=-33d 14' 59.08" in the EPIC camera (within an error circle of 3".5) and at alpha=17h 55m 22.32s, delta= -33d 14' 57.49" in the U and UW1 filters of the Optical Monitor (within an error circle of 2").
In the X-rays band, the source is detected at a 3.65 sigma level in the 0.3-8.0 keV band with a count rate of 0.36 cts/ks (MOS equivalent count rate), and at a 4.95 sigma level in the 5.0-8-0 keV band. The X-ray spectrum is poor in count statistics, a tentative fit with an absorbed optically thin thermal plasma gives nH >1.5e22 cm^-2 and a temperature kT >10 keV. The UW1 (2190\AA) magnitude was 17.815+- 0.007 and the U (3440\AA) magnitude was 16.606+-0.002, while the source was not detected in the UWM2 (2310\AA) filter.
The quiescent X-ray spectrum can be classified as delta-type (following the recent classification scheme proposed by Luna et al 2013, A&A, 436, 212), which likely originates in the accretion-disk boundary layer, in analogy with T CrB, another symbiotic recurrent nova.
