14 ASTRONOMY • MAY 2020
QUA NTUM GRAVITY
Fast radio bursts (FRBs) are
short, powerful blasts of energy
that originate outside our galaxy. Only
a few repeat, while most pop off only
once. For more than a decade, astrono-
mers have sought to understand these
strange f lashes and, in recent years,
have begun to trace some FRBs back
to their origins. In a paper published
January 6 in Nature, researchers
announced they have tracked yet
another FRB to its host galaxy. It is the
fifth time an FRB has been traced to
its origin, and only the second time a
repeating FRB has been pinpointed.
Combining observations from eight
separate telescopes, a team of astrono-
mers tracked the burst, which is called
FRB 180916.J0158+65, to a spiral galaxy
nearly half a billion light-years away.It is the closest FRB tracked to date
and lies within an outer arm of its host
galaxy, where stars are rapidly forming.
The spiral host is similar to our own
Milky Way, however, making it unlike
any other galaxy in which an FRB has
been found before. The only other
repeating FRB that astronomers have
tracked, FRB 121102, comes from a tiny,
distant dwarf galaxy 3 billion light-
years away — a dramatically different
environment than a spiral galaxy near
our own.
“This object’s location is radically
different from that of not only the previ-
ously located repeating FRB, but also all
previously studied FRBs,” said study co-
author Kenzie Nimmo of the University
of Amsterdam in a press release. And
that has implications, the team says, forthe types of conditions that cause FRBs,
repeating and nonrepeating.
The current leading theory is that
FRBs are produced by neutron stars, the
highly magnetized remnants of massive
stars. While this could be the case for
some FRBs, it may not be the cause of
all of them. The more FRBs astrono-
mers identify and track, the more
diverse the population becomes. “It may
be that FRBs are produced in a large
zoo of locations across the universe and
just require some specific conditions to
be visible,” Nimmo said.
The team, along with many others,
aims to track an increasing number of
FRBs to their hosts. They hope more
information on where FRBs originate
will ultimately reveal what’s causing
these strange f lashes of energy. — A.K.Second repeating fast radio burst
tracked, deepening mystery
UP IN ARMS.
FRB 180916 lies
in a Milky Way-
like spiral galaxy
500 million light-
years away. The
location of the
FRB (circled) in
one of the galaxy’s
star-forming spiral
arms challenges
astronomers’
ideas about the
origin of these
mysterious bursts.
GEMINI OBSERVATORY/NSF'S
NATIONAL OPTICAL-INFRARED
ASTRONOMY RESEARCH
LABORATORY/AURA