Abstract
There are by now ten published detections of fast radio bursts (FRBs), single
bright GHz-band millisecond pulses of unknown origin. Proposed explanations
cover a broad range from exotic processes at cosmological distances to
atmospheric and terrestrial sources. Loeb et al. have previously suggested that
FRB sources could be nearby flare stars, and pointed out the presence of a
W-UMa-type contact binary within the beam of one out of three FRB fields that
they examined. Using time-domain optical photometry and spectroscopy, we now
find possible flare stars in additional FRB fields, with one to three such
cases among eight FRB fields studied. We evaluate the chance probabilities of
these possible associations to be in the range 0.1% to 9%, depending on the
input assumptions. Further, we re-analyze the probability that two FRBs
recently discovered 3 years apart within the same radio beam are unrelated.
Contrary to other claims, we conclude with 99% confidence that the two events
are from the same repeating source. The different dispersion measures between
the two bursts then rule out a cosmological origin for the dispersion measure,
but are consistent with the flare-star scenario with a varying plasma blanket
between bursts. Finally, we review some theoretical objections that have been
raised against a local flare-star FRB origin, and show that they are incorrect.
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