A long serendipitous XMM–Newton observation of the intermediate polar XY Ari1

Abstract

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 We present results from a detailed analysis of an unpublished archival observation using XMM-Newton EPIC pn and MOS data in a quiescent state of XY Ari.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 at 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 CEVMKL model yield maximum plasma temperature of $28^{+3.1}_{-2.9}$ keV with an iron abundance $\mathrm{Fe}/\mathrm{Fe}_\odot=0.37^{+0.06}_{-0.05}$. We find two intrinsic partial covering absorption columns of $6.2^{+1.0}_{-0.9} \times 10^{22}$ and $105.3^{+35.4}_{-30.4} \times 10^{22} \,\mathrm{cm^{-2}}$ with covering fractions of $0.53^{+0.05}_{-0.04}$, $0.41^{+0.14}_{-0.13}$ respectively. In addition, a Gaussian emission line at $6.43^{+0.01}_{-0.02}$ keV with an equivalent width of $51^{+12}_{-10}$ eV is required to account for fluorescent emission from neutral iron. The X-ray luminosity of the source is $4.2 \times 10^{32} \,\mathrm{erg \,s^{-1}}$ in the 0.2-10.0 keV energy band.