SSRP Abstract

Board 29: Variations in Mass Accretion Rate in a High-Mass X-Ray Binary System

Student Scientist: Malcolm Henderson ’25
Research Mentor: John Blondin (Department of Physics, North Carolina State University)

When a neutron star orbits a massive supergiant companion, it gravitationally captures material that is expelled from the supergiant. As the material falls onto the neutron star, it heats up and emits X-rays. The X-rays affect the material coming off the supergiant by slowing and heating it, which in turn influences how that material is captured by the neutron star. I am studying how this interaction affects the system over a long period of time.

Binary systems consisting of an OB supergiant star and a compact companion can produce X-ray emissions when mass from the stellar wind of the supergiant is accreted onto the compact companion. These systems are called high mass X-ray binaries (HMXBs). In these systems, the X-ray emissions from the compact object can heat ionize the stellar wind from the OB supergiant, stopping it from being accelerated. This creates a slower wind that produces a higher mass accretion rate and therefore higher X-ray luminosity. This continues until the X-ray luminosity is high enough to cut off the solar wind, causing the mass accretion and X-ray luminosity to drop. This cycle creates a variable mass accretion rate. I will be using hydrodynamic simulations to model the HMXB system Vela X-1 in 2 and 3 dimensions to observe the rate at which mass is accreted onto the neutron star in the system over a period of time. I will be using the hydrodynamic models to find if there are any stable states in the mass accretion rate and under what conditions those stable states might occur.