We present the largest compilation to date of optical observations during and
following fast radio bursts (FRBs). The data set includes our dedicated
simultaneous and follow-up observations, as well as serendipitous archival
survey observations, for a sample of 15 well-localized FRBs, including 8
repeating and 7 one-off sources. Our simultaneous (and nearly simultaneous with
a 0.4-sec delay) optical observations of 7 (1) bursts from the repeating FRB
20220912A provide the deepest such limits to date for any extragalactic FRB,
reaching a luminosity limit of Ξ½LΞ½ββ²1042 erg sβ1
(β²2Γ1041 erg sβ1); these observations are also the
deepest to date in terms of optical flux to radio fluence ratio of foptβ/Fradioββ²10β7 msβ1 (β²10β8 msβ1),
and place a limit on the flux ratio of foptβ/fradioββ²0.02
on a msec timescale or β²2Γ10β5 (β²10β6) on a sec
timescale. These simultaneous limits provide useful constraints in the context
of FRB emission models, such as the pulsar magnetosphere and pulsar nebula
models. Interpreting all available optical limits in the context of the FRB
synchrotron maser model, we find that they constrain the flare energies to
β²1043β1047 erg (depending on the distances of the various
repeating FRBs, with β²1039 erg for SGR 1935+2154). These limits
are generally at least an order of magnitude larger than the energies inferred
from the FRBs themselves, although in the case of FRB 20220912A our
simultaneous and rapid follow-up observations severely restrict the model
parameter space. We conclude by exploring the potential of future rapid
response and simultaneous observations with large optical telescopes.Comment: 22 pages, 8 figures, submitted to ApJL. Please let us know if we
missed any optical and/or radio observations of the FRB sampl