Probing ultra-diffuse galaxies out to the virial radius of the Coma
  cluster with XMM-Newton
  We probe the formation scenarios and the active galactic nuclei (AGN)
occupation fraction of ultra-diffuse galaxies (UDGs) in the nearby Coma cluster
by utilizing XMM-Newton observations of 779 out of 854 UDG candidates
identified by Subaru survey. Their origin is probed by measuring the dark
matter halo mass of the stacked sample of UDGs and the population of low-mass
X-ray binaries residing in globular clusters. Our measurements suggest that the
average UDG population does not have a substantial amount of hot gas or a large
number of globular clusters. This supports the formation scenario, in which
UDGs are puffed-up dwarf galaxies, agreeing with that obtained for 404 Coma
cluster UDGs using Chandra. We also determine AGN occupation fraction of UDGs
by cross-correlating the position of UDGs with the detected point sources in
Coma. We detect three X-ray sources with detection significance $\sigma \geq 5$
that could be off-centre AGN within 5 arcsec from the centre of the UDG 317,
UDG 432, and UDG 535. We identify an optical counterpart for the X-ray source
associated with the UDG 317, suggesting that this source is more likely an
off-centre AGN. Based on the current data, however, we cannot conclusively
constrain whether the detected AGN is residing in the Coma cluster or not.
