26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Periodic radio and X-ray emission from an accreting white dwarf binary

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Astronomy (ASTRO)

Speaker

Kovi Rose (University of Sydney)

Description

I will present the discovery and characterisation of a novel, gravitationally-accreting white dwarf binary system, identified through optical spectroscopy and radio-wavelength observations. This system displays a short orbital period of ~1.3 hours, determined from Doppler shifts in Balmer emission lines, and exhibits unique radio emission characteristics.

We observed periodic bursts of elliptically polarised radio emission - displaying frequency drift and intermittency - aligned with the orbital period. As well as coincident UV emission and orbitally modulated X-ray emission.

This system occupies a crucial evolutionary space, bridging cataclysmic variables and long-period transients, with an orbital period shorter than other known long-period transient associated with white dwarfs. The radio emission's high brightness temperature and elliptical polarisation necessitates a coherent mechanism. We find the observations can be explained by a relativistic electron cyclotron maser operating within the magnetic field lines connecting the white dwarf and its low-mass stellar companion.

Our analysis allows us to probe the system's magnetic field structure and plasma transfer dynamics. I will discuss the implications of these findings for understanding the emission mechanisms of long-period transients and the evolutionary pathways of close white dwarf binaries.