CRA Seminar – Tolga Guver [Host Matthew Liska]
February 13 @ 3:30 pm - 4:30 pm
Title: Thermonuclear X-ray Bursts in the NICER Era
Abstract: Thermonuclear X-ray bursts are sudden flashes observed from some low-mass X-ray binaries. Time-resolved spectral analysis and long-term observations have revealed that they occur due to the unstable thermonuclear burning of the accreted matter on the surface of the neutron star. They typically last a few tens of seconds, and the recurrence of these events seems to track the amount of matter accreted. Observations of thermonuclear X-ray bursts provide a wealth of information about thermonuclear burning, accretion physics, and the properties of the host systems, while also playing a crucial role in measurements of neutron star masses and radii. In this talk, I will focus on X-ray burst observations with the Neutron Star Interior Composition Explorer (NICER) since its launch in 2017. With its large effective area in the soft X-ray band, NICER has allowed us to probe the interaction of X-ray bursts with their surroundings in a systematic way for the first time. I will summarize our findings on the excess soft X-ray emission observed during the bursts and how it can be interpreted in terms of changes in the mass accretion rate during the bursts and/or the reflection of the X-ray burst emission off the accretion disk.