  We report a multiwavelength (X-ray, ultraviolet/optical/infrared, radio)
analysis of the relativistic tidal disruption event candidate Sw J2058+05 from
3 months to 3 yr post-discovery in order to study its properties and compare
its behavior with that of Sw J1644+57. Our main results are as follows. (1) The
long-term X-ray light curve of Sw J2058+05 shows a remarkably similar trend to
that of Sw J1644+57. After a prolonged power-law decay, the X-ray flux drops
off rapidly by a factor of $\gtrsim 160$ within a span of $\Delta$$t$/$t$ $\le$
0.95. Associating this sudden decline with the transition from super-Eddington
to sub-Eddington accretion, we estimate the black hole mass to be in the range
of $10^{4-6}$ M$_{\odot}$. (2) We detect rapid ($\lesssim 500$ s) X-ray
variability before the dropoff, suggesting that, even at late times, the X-rays
originate from close to the black hole (ruling out a forward-shock origin). (3)
We confirm using HST and VLBA astrometry that the location of the source
coincides with the galaxy's center to within $\lesssim 400$ pc (in projection).
(4) We modeled Sw J2058+05's ultraviolet/optical/infrared spectral energy
distribution with a single-temperature blackbody and find that while the radius
remains more or less constant at a value of $63.4 \pm 4.5$ AU ($\sim 10^{15}$
cm) at all times during the outburst, the blackbody temperature drops
significantly from $\sim$ 30,000 K at early times to a value of $\sim$ 15,000 K
at late times (before the X-ray dropoff). Our results strengthen Sw J2058+05's
interpretation as a tidal disruption event similar to Sw J1644+57.
