Indications of magnetic accretion in Swift J0826.2−7033^⋆

¹ Astronomy Division, Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, 263001, India
² Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli, Italy
³ CRESST II and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD, 20771, USA
⁴ Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA
⁵ International Space Science Institute (ISSI), Hallerstrasse 6, CH-3012 Bern, Switzerland
⁶ Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
⁷ Istituto Nazionale di Astrofisica, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 101, I-40129 Bologna, Italy
⁸ Instituto de Astrofísica, Facultad de Ciencias Exactas, Universidad Andrés Bello, Fernández Concha 700, Las Condes, Santiago, Chile

^⋆⋆ Corresponding authors; rawatnikita221@gmail.com; nikita@aries.res.in; domitilla.demartino@inaf.it

Received: 24 April 2024
Accepted: 20 September 2024

Abstract

We present our findings from the first long X-ray observation of the hard X-ray source Swift J0826.2−7033 with XMM-Newton, which has shown characteristics of magnetic accretion. The system appears to have a long orbital period (∼7.8 h) accompanied by short timescale variabilities, which we tentatively interpret as the spin and beat periods of an intermediate polar. These short- and long-timescale modulations are energy-independent, suggesting that photoelectric absorption does not play any role in producing the variabilities. If our suspected spin and beat periods are true, then Swift J0826.2−7033 accretes via disc-overflow with an equal fraction of accretion taking place via disc and stream. The XMM-Newton and Swift-BAT spectral analysis reveals that the post-shock region in Swift J0826.2−7033 has a multi-temperature structure with a maximum temperature of ∼43 keV, which is absorbed by a material with an average equivalent hydrogen column density of ∼1.6 × 10²² cm⁻² that partially covers ∼27% of the X-ray source. The suprasolar abundances, with hints of an evolved donor, collectively make Swift J0826.2−7033 an interesting target, which likely underwent a thermal timescale mass transfer phase.