A long serendipitous XMM-Newton observation of the intermediate polar XY Ari

Camurdan D. Z., BALMAN Ş., Burwitz V.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.477, no.3, pp.4035-4045, 2018 (SCI-Expanded) identifier


XY Ari is one of the few known eclipsing intermediate polars. We present results from a detailed analysis of an unpublished archival observation using XMM-Newton EPIC pn and MOS data in a quiescent state of XY Ari. The X-ray orbital modulation and spin-pulse variations were investigated for energy-dependent modulations in different energy bands. The broad orbital modulation observed with various observations was confirmed with XMM-Newton in the hard X-ray (>1.6 keV). The EPIC light curves folded at the spin phases show a double-peak profile, as expected from two-pole accretion. The pulse profile is found to be energy-dependent. Hardness-ratio variations and energy modulation depth during spin modulation can be explained by photoelectric absorption. The simultaneously fitted EPIC spectra with a multi-temperature plasma emission model (CEVMKL) model yield a maximum plasma temperature of 28(-2.9)(+3.1) keV with an iron abundance Fe/Fe-circle dot = 0.37(-0.05)(+0.06) . We find two intrinsic partial covering absorption columns of 6.2(-0.9)(+1.0) x 10(22) and 105.3(-30.4)(+35.4) x 10(22) cm(-2) with covering fractions of 0.53(-0.04)(+0.05), 0.41(-0.13)(+0.14), respectively. In addition, a Gaussian emission line at 6.43(-0.02)(+0.01) keV with an equivalent width of 51(-10)(+12) eV is required to account for fluorescent emission from neutral iron. The X-ray luminosity of the source is 4.2 x 10(32) erg s(-1) in the 0.2-10.0 keV energy band.