A deep XMM-Newton observation of the X-Persei-like binary system CXOU J225355.1+624336

LA PALOMBARA, NICOLANICOLALA PALOMBARASIDOLI, LaraLaraSIDOLIEsposito, P.P.EspositoISRAEL, Gian LucaGian LucaISRAELRODRIGUEZ CASTILLO, Guillermo AndresGuillermo AndresRODRIGUEZ CASTILLO2022-06-092022-06-0920210004-6361http://hdl.handle.net/20.500.12386/32254We report on the follow-up XMM-Newton observation of the persistent X-ray pulsar CXOU J225355.1+624336, which was discovered with the CATS@BAR project on archival Chandra data. The source was detected at fX(0.5−10 keV) = 3.4 × 10−12 erg cm−2 s−1, a flux level that is fully consistent with previous observations performed with ROSAT, Swift, and Chandra. When compared with previous measurements, the measured pulse period P = 46.753(3) s implies a constant spin down at an average rate of Ṗ = 5.3 × 10−10 s s−1. The pulse profile is energy dependent, showing three peaks at low energy and a less structured profile above about 3.5 keV. The pulsed fraction slightly increases with energy. We described the time-averaged EPIC spectrum with four different emission models: a partially covered power law, a cutoff power law, and a power law with an additional thermal component (either a black body or a collisionally ionised gas). In all cases we obtained equally good fits, so it was not possible to prefer or reject any emission model on a statistical basis. However, we disfavour the presence of thermal components since their modeled X-ray flux, resulting from a region larger than the neutron star surface, would largely dominate the X-ray emission from the pulsar. The phase-resolved spectral analysis showed that a simple flux variation cannot explain the source variability and proved that there is a spectral variability along the pulse phase. The results of the XMM-Newton observation confirmed that CXOU J225355.1+624336 is a Be X-ray binary (BeXB) with a low luminosity (LX ∼ 1034−35 erg s−1), limited variability, and a constant spin down. Therefore, these results reinforce its source classification as a persistent BeXB. Based on observations obtained with XMM-Newton, an ESA science mission, with instruments and contributions directly funded by ESA Member States and NASA.STAMPAenA deep XMM-Newton observation of the X-Persei-like binary system CXOU J225355.1+62433610.1051/0004-6361/202140760https://www.aanda.org/articles/aa/full_html/2021/05/aa40760-21/aa40760-21.html2021A&A...649A.118LFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos