Institut de Planétologie et d’Astrophysique de Grenoble

Constraining the Physics of the X-ray Irradiated Accretion Discs in Low-Mass X-ray Binaries : A GX339-4 Case Study

Bailey Tetarenko (University of Michigan)
Thursday February 14th - 11am
IPAG Seminar Room - IPAG

From how planets and newborn stars form to the evolution of entire galaxies, many astrophysical objects grow and evolve by accumulating mass through a disc. However, currently our understanding of the detailed physics governing this process is fragmented due to the limits of theoretical work and missing observational constraints. The recurring outbursts associated with matter flowing onto compact stellar remnants (black holes, neutron stars, white dwarfs) in low-mass X-ray binary systems provide a``real-time’’ view of disc-accretion in action and thus, a means to study this poorly understood process. The multi-wavelength light-curves of these bright outbursts act as powerful diagnostics, allowing one to probe the physics behind the mechanisms driving the mass transport through, and the heating of, the accretion discs in these astrophysical systems. As such, we have developed a methodology that combines optical and X-ray observations with accretion theory to tackle the complex, multi-scale problem of understanding the evolution of accretion disc structure and geometry throughout the course of a low-mass X-ray binary outbursts. In this talk, I will present the application of this methodology to the Galactic low-mass X-ray binary GX339-4, and demonstrate how having the ability to track changes in physical properties of the X-ray irradiating source heating these accretion discs on daily/weekly timescales throughout outburst may gives us clues towards understanding some of the wide range of outburst behaviour exhibited by this source over the past two decades.