Investigating ACIS Spectra in Archival Chandra Data

Live Poster Session: Zoom Link
Thursday, July 30th 1:15-2:30pm EDT

Abstract: One major source of extragalactic X-rays are X-ray binaries, when a star orbits a compact object – a black hole, neutron star, or white dwarf. As material falls from the star onto the compact object, it loses gravitational potential and heats up enough to emit X-ray photons. To learn more about these objects, 136 X-ray sources were selected and analyzed from an existing database of Chandra X-Ray Observatory Advanced CCD Imaging Spectrometer (ACIS) observations. Sources were selected based on a flux-count range. Only sources with normalized photon counts between 1000 and 2000 over the whole observation were considered. Such sources are high enough count to perform statistically significant analysis, but low enough count that many have been passed over in prior studies. Furthermore, only sources outside the Milky Way or Magellanic Clouds were selected. Since galactic sources are so much closer than extragalactic ones, bright X-Ray sources within the galaxy are much different than ones found outside the galaxy. For each source, regions and raw spectra data were provided. These spectra were fitted to 10 different models in various combinations. When fitted to a source, these models provide information about the physical properties of the source. They tell about the sources’ temperature, the presence of an accretion disk, or the abundance of hydrogen in sources’ host galaxy. Of the 136 sources, 104 were fit well by the chosen models. The rest were analyzed, looking for evidence of pileup and over subtraction in order to find a suitable fit. In addition, light curves were created for all 136 sources, looking for evidence of inter-observation variability. 17 of the sources were found to be variable. These sources’ spectra were split based on count rate changes in their light curves. The split spectra were refit, looking for changes in spectral type within an observation.

summer_poster_larner_4-Seth-Larner

Live Poster Session: Zoom Link
Thursday, July 30th 1:15-2:30pm EDT