Title: “A Spectroscopic point of view on Central Engines in Accreting Neutron Stars”

Seminar by Nicolas Trueba, PhD student (Department of Astronomy, University of Michigan)

Nicolas Trueba

Wednesday 30th of March, 14:15 p.m

Google Meet Link: https://meet.google.com/ots-rija-hyc

Abstract: “High-resolution spectroscopic studies of absorbing disk winds and atmospheres in low-mass X-ray binaries (LMXBs) are key in advancing our understanding of these systems and the accretion process, in general. These analyses, however, do not account for an important geometric effect expected to be present and detectable in the data: The contribution of a small component of the absorber’s orbital motion to the velocity width of absorption lines due to the relative size of the central engine. We developed a new method for constraining the size of the central engine in accreting compact objects by quantifying the magnitude of this effect. We applied this method on Chandra/HETG spectra of three short-period neutron star X-ray binaries in which we discovered evidence of gravitationally redshifted absorption owing to an inner-disk atmosphere. In this talk, I will explain how this effect works and describe the methodology we devised to model this effect in order to constrain the size of the central engine. I will also discuss our results on redshifted lines from inner disk atmospheres in ultra-compact X-ray binaries and why these systems are excellent laboratories for applying this technique”.