2024/03/28 by J. Gerber, Jeremy Hare, Gerber, Julian +19
Physics and Astronomy · #Astrophysical Phenomena and Observations #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2403.19170
openalex publication_date 2024/03/28 · openalex created_date 2024/03/30 · openalex updated_date 2026/07/28
IGR J18434-0508 is a Galactic Intermediate Polar (IP) type Cataclysmic Variable (CV) previously classified through optical spectroscopy. The source is already known to have a hard Chandra spectrum. In this paper, we have used follow-up XMM-Newton and NuSTAR observations to measure the white dwarf (WD) mass and spin period. We measure a spin period of P = 304.4 +/- 0.3 s based on the combined MOS1, MOS2, and pn light curve. Although this is twice the optical period found previously, we interpret this value to be the true spin period of the WD. The source has an 8 +/- 2% pulsed fraction in the 0.5-10 keV XMM-Newton data and shows strong dips in the soft energy band (0.5-2 keV). The XMM-Newton and NuSTAR joint spectrum is consistent with a thermal bremsstrahlung continuum model with an additional partial covering factor, reflection, and Fe line Gaussian components. Furthermore, we fit the joint spectrum with the post-shock region "ipolar" model which indicates a high WD mass > ∼ 1.36 Msun, approaching the Chandrasekhar limit.