  Hot dust-obscured galaxies (Hot DOGs) are a luminous, dust-obscured
population recently discovered in the WISE All-Sky survey. Multiwavelength
follow-up observations suggest that they are mainly powered by accreting
supermassive black holes (SMBHs), lying in dense environments, and being in the
transition phase between extreme starburst and UV-bright quasars. Therefore,
they are good candidates for studying the interplay between SMBHs, star
formation and environment. W2246$-$0526 (thereafter, W2246), a Hot DOG at
$z\sim4.6$, has been taken as the most luminous galaxy known in the Universe.
Revealed by the multiwavelength images, the previous Herschel SPIRE photometry
of W2246 is contaminated by a foreground galaxy (W2246f), resulting in an
overestimation of its total IR luminosity by a factor of about 2. We perform
the rest-frame UV/optical-to-far-IR spectral energy distribution (SED) analysis
with SED3FIT and re-estimate its physical properties. The derived stellar mass
$M_\star = 4.3\times10^{11}~M_\odot$ makes it be among the most massive
galaxies with spectroscopic redshift $z>4.5$. Its structure is extremely
compact and requires an effective mechanism to puff-up. Most of ($>95\%$) its
IR luminosity is from AGN torus emission, revealing the rapid growth of the
central SMBH. We also predict that W2246 may have a significant molecular gas
reservoir based on the dust mass estimation.

Astrophysics of Galaxies