Swift Deep Galactic Plane Survey classification of Swift J170800−402551.8 as a candidate intermediate polar cataclysmic variable
B O’Connor, E Göğüş, J Hare, K Mukai, D Huppenkothen, J Brink, D A H Buckley, A Levan, M G Baring, R Stewart, C Kouveliotou, P Woudt, E Bellm, S B Cenko, P A Evans, J Granot, C Hailey, F Harrison, D Hartmann, A J van der Horst, L Kaper, J A Kennea, S B Potter, P O Slane, D Stern, R A M J Wijers, G Younes- Space and Planetary Science
- Astronomy and Astrophysics
Abstract
Here, we present the results of our multi-wavelength campaign aimed at classifying Swift J170800−402551.8 as part of the Swift Deep Galactic Plane Survey (DGPS). We utilized Target of Opportunity (ToO) observations with Swift, Chandra, NICER, XMM-Newton, NuSTAR, and the Southern African Large Telescope (SALT), as well as multi-wavelength archival observations from Gaia, VPHAS, and VVV. The source displays a periodicity of 784 s in our XMM-Newton observation. The X-ray spectrum (XMM-Newton and NuSTAR) can be described by thermal bremsstrahlung radiation with a temperature of kT ≈ 30 keV. The phase-folded X-ray lightcurve displays a double-peaked, energy-dependent pulse-profile. We used Chandra to precisely localize the source, allowing us to identify and study the multi-wavelength counterpart. Spectroscopy with SALT identified a Balmer Hα line, and potential HeI lines, from the optical counterpart. The faintness of the counterpart (r ≈ 21 AB mag) favors a low-mass donor star. Based on these criteria, we classify Swift J170800−402551.8 as a candidate intermediate polar cataclysmic variable, where the spin period of the white dwarf is 784 s.