Dartmouth Events

Physics & Astronomy - Astronomy Seminar - Victoria Grinberg - MIT

Title: "Probing Accretion Physics and Stellar Winds with X-Ray Binaries"

Thursday, November 3, 2016
2:15pm – 3:15pm
Wilder 202
Intended Audience(s): Public
Categories: Lectures & Seminars

Title:  X-ray binaries, systems that consist of a neutron star or black hole and
a non-degenerate stellar companion, are among the most variable objects
on the sky, with variability timescales ranging from millisecond
quasi-periodic oscillations over day-long binary orbits to year-long
duty cycles. Because of mass-scaling, they can be seen as AGN for the
impatient and are the perfect tools to investigate the dynamics of
accretion and ejection flows close to compact objects. In high mass
X-ray binaries, where accretion is fueled through the stellar wind of an
O/B star, the compact object can also serve as an unique in situ probes
of the structured (“clumpy”) winds of massive stars.

Here, I will use two of the brightest X-ray binaries, Cygnus X-1 and
Vela X-1 as examples. I will concentrate on an observational approach
and show how, by combining X-ray spectral and variability with gamma-ray
polarization analyses, we can constrain the accretion and ejection
processes taking place close to the black hole and constrain the
importance of jets in the high energy regime. At lower energies, the
X-ray emission is additionally modified by the wind of the companion,
with absorption changing on timescales of kiloseconds and below.
Carefully disentangling the continuum variability and true changes in
absorption allows us to investigate the porosity and structure of
stellar winds and to X-ray individual clumps revealing their onion-shell
like structure.

For more information, contact:
Tressena Manning
603-646-2854

Events are free and open to the public unless otherwise noted.