Looking for Dust-Scattering Light Echoes
Grade Level at Time of Presentation
Senior
Major
Astrophysics
Minor
Philosophy
Institution
University of Louisville
KY House District #
44
KY Senate District #
33
Faculty Advisor/ Mentor
Sebastian Heinz; Lia Corrales; Gerard Williger
Department
Physics and Astronomy
Abstract
Galactic X-ray transient sources such as neutron stars or black holes sometimes undergo an outburst in X-rays. Ring structures have been observed around three such sources, produced by the X-ray light being scattered by dust grains between us and the neutron star. These dust-scattering light echoes have proven to be a useful tool for measuring and constraining distances in our Milky Way galaxy, mapping its dust structure, and determining the dust make-up in the clouds producing the scattering echo. Detectable light echoes require a sufficient quantity of dust along our line of sight, as well as bright, short-lived X-ray flares. Using data from the Monitor of All-Sky X-ray Image (MAXI) aboard the International Space Station, we ran a peak finding algorithm in Python to look for characteristic flare events. Each flare was characterized by its fluence, the integrated flux of the flare over time. We measured the distribution of flare fluences to show how many observably bright flares were recorded by MAXI. This work provides a parent set for dust echo searches in archival X-ray data and will inform observing strategies with current and future X-ray telescope missions such as Athena and Lynx. The more echoes we can detect, the better we can understand the Galaxy we live in.
Looking for Dust-Scattering Light Echoes
Galactic X-ray transient sources such as neutron stars or black holes sometimes undergo an outburst in X-rays. Ring structures have been observed around three such sources, produced by the X-ray light being scattered by dust grains between us and the neutron star. These dust-scattering light echoes have proven to be a useful tool for measuring and constraining distances in our Milky Way galaxy, mapping its dust structure, and determining the dust make-up in the clouds producing the scattering echo. Detectable light echoes require a sufficient quantity of dust along our line of sight, as well as bright, short-lived X-ray flares. Using data from the Monitor of All-Sky X-ray Image (MAXI) aboard the International Space Station, we ran a peak finding algorithm in Python to look for characteristic flare events. Each flare was characterized by its fluence, the integrated flux of the flare over time. We measured the distribution of flare fluences to show how many observably bright flares were recorded by MAXI. This work provides a parent set for dust echo searches in archival X-ray data and will inform observing strategies with current and future X-ray telescope missions such as Athena and Lynx. The more echoes we can detect, the better we can understand the Galaxy we live in.