Optical Counterparts of ULXs in Two Dwarf Galaxies: NGC 4861 and NGC
  4449
  We present the results of a search for optical candidates of Ultraluminous
X-ray sources (ULXs) in two dwarf galaxies: NGC 4861 and NGC 4449 using Hubble
Space Telescope {\it HST} archival data. With a precise astrometry, we confirm
that NGC 4861 X1 associated with an HII complex as reported by
\cite{2014MNRAS.441.1841T} and we conclude that NGC 4861 X2 resides in a young
star group with 400$\pm$80 M$\odot$. We also find that NGC 4449 X7 is
associated with three optical candidates within an error radius of 0$\farcs$2
at the 90$\%$ confidence level. Absolute magnitudes (M$_{v}$) of these
candidates are determined as $-$5.0 and $-$4.1. The age and mass values for the
three candidates by using stellar evolutionary tracks are estimated as 40-50
Myr and $\sim$8 M$\odot$, respectively. The locations of optical candidates
suggest possible association with a nearby group of stars. In addition, we
analyzed the previously unused archival data of {\it XMM-Newton}, {\it Chandra}
and {\it Swift} where the sources detected. Although the X-ray spectral data do
not allow us to discriminate between physical models, long-term data at hand
are consistent with the sources being in luminous hard states.
