Chronicling the Host Galaxy Properties of the Remarkable Repeating FRB
  20201124A
  We present the Australian Square Kilometre Array Pathfinder (ASKAP)
localization and follow-up observations of the host galaxy of the repeating
fast radio burst (FRB) source, FRB20201124A, the fifth such extragalactic
repeating FRB with an identified host. From spectroscopic observations using
the 6.5-m MMT Observatory, we derive a redshift of $z=0.0979 \pm 0.0001$, a
star formation rate inferred from H$\alpha$ emission of SFR(H$\alpha$) $\approx
2.1 M_{\odot}$ yr$^{-1}$, and a gas-phase metallicity of 12+log(O/H)$\approx
9.0$. By jointly modeling the 12-filter optical-mid-infrared (MIR) photometry
and spectroscopy of the host, we infer a median stellar mass of $\approx 2
\times 10^{10} M_{\odot}$, internal dust extinction of $A_V\approx 1-1.5$ mag,
and a mass-weighted stellar population age of $\approx 5-6$ Gyr. Connecting
these data to the radio and X-ray observations, we cannot reconcile the
broad-band behavior with strong AGN activity and instead attribute the dominant
source of persistent radio emission to star formation, likely originating from
the circumnuclear region of the host. The modeling also indicates a hot dust
component contributing to the MIR luminosity at a level of $\approx 10-30\%$.
We model the host galaxy's star formation and mass assembly histories, finding
that the host assembled $>90\%$ of its mass by 1 Gyr ago and exhibited a fairly
constant SFR for most of its existence, with no clear evidence of past
star-burst activity.
