Classifying IGR J15038-6021 as a magnetic CV with a massive white dwarf

Abstract

Cataclysmic variables (CVs) are binary systems consisting of a white dwarf (WD) accreting matter from a companion star. Observations of CVs provide an opportunity to learn about accretion disks, the physics of compact objects, classical novae, and the evolution of the binary and the WD that may ultimately end in a type Ia supernova (SN). As type Ia SNe involve a WD reaching the Chandrasekhar limit or merging WDs, WD mass measurements are particularly important for elucidating the path from CV to type Ia SN. For intermediate polar (IP) type CVs, the WD mass is related to the bremsstrahlung temperature of material in the accretion column, which typically peaks at X-ray energies. Thus, the IPs with the strongest hard X-ray emission, such as those discovered by the INTEGRAL satellite, are expected to have the highest masses. Here, we report on XMM-Newton, NuSTAR, and optical observations of IGR J15038-6021. We find an X-ray periodicity of 1678+/-2s, which we interpret as the WD spin period. From fitting the 0.3-79 keV spectrum with a model that uses the relationship between the WD mass and the post-shock temperature, we measure a WD mass of 1.36+0.04-0.11 Msun. This follows an earlier study of IGR J14091-6108, which also has a WD with a mass approaching the Chandrasekhar limit. We demonstrate that these are both outliers among IPs in having massive WDs and discuss the results in the context of WD mass studies as well as the implications for WD mass evolution.

Accepted for publication in MNRAS

References in corpus (12)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• A highly magnetised and rapidly rotating white dwarf as small as the Moon
• Hard X-ray emission from the Galactic ridge
• Measuring the masses of magnetic white dwarfs: A NuSTAR Legacy Survey
• High-resolution spectroscopy of the intermediate polar EX Hydrae. I. Kinematic study and Roche tomography
• Progenitor constraints on the Type-Ia supernova SN2011fe from pre-explosion Hubble Space Telescope HeII narrow-band observations
• The intermediate polar cataclysmic variable GK Persei 120 years after the nova explosion: a first dynamical mass study
• Hard X-ray luminosity functions of cataclysmic variables: Joint Swift/BAT and Gaia data
• 15 years of Galactic surveys and hard X-ray Background measurements
• Chandra Observations of High Energy X-ray Sources Discovered by INTEGRAL
• Classifying IGR J18007-4146 as an intermediate polar using XMM and NuSTAR
• Chandrasekhar-mass white dwarfs are the progenitors of a small fraction of Type Ia supernovae according to nucleosythesis constraints

Cited by in corpus (2)

• Indications of magnetic accretion in Swift J0826.2-7033
• Classification of IGR J20084+3221 as an Intermediate Polar using X-ray and Optical Observations