Speaker
Description
In X-ray observations, scattering of photons on dust along the line of sight can lead to the formation of an extended X-ray halo around any source. We have used data from eROSITA to study these dust scattering halos around 29 point sources in eRASS 1.
For bright sources, which are needed to observe halos at the high scattering angles made accessible by eROSITA, pile-up limits our abilities to constrain the source and halo flux by fitting the surface brightness distribution, as has been done in previous studies with, e.g., ROSAT. Instead, we fit spectra extracted from annuli around the sources using the xscat model, excluding the inner, piled-up source regions. This allows us to simultaneously fit the unscattered source spectrum and the dust distribution.
We find that the hydrogen column density in absorption provides an upper limit for the scattering column densities, likely due to absorption within some source systems as well as scattering close to the sources, which is not resolved by eROSITA's PSF.
