Benito Marcote, Kenzie Nimmo, and Shriharsh Tendulkar
The First Repeating Fast Radio
Burst in a Spiral Galaxy
Observations with the European VLBI Network and the Gemini North
telescope have localized, for the second time in history, a Fast Radio
Burst (FRB) source that repeats. Known as FRB 180916.J0158+65, it
originates from a prominent star-forming region in a spiral galaxy
that resembles our Milky Way. Surprisingly, this source and its host
galaxy are radically different from those of the first repeating FRB.
The observed diversity in hosts and local environments may point to
multiple classes of FRBs with different progenitors.
Fast Radio Bursts (FRBs) are extremely bright radio flashes of millisecond duration and ex-
tragalactic origin. Astronomers have known of their existence for only about a decade. The
first FRB was discovered in 2007, in archival pulsar data from the 64-meter Parkes radio
telescope in New South Wales, Australia. These data revealed a single, bright signal lasting
only a few milliseconds (now known as the Lorimer Burst; Lorimer et al., 2007). Since then
less than a hundred FRBs have been discovered. Despite estimates that some 1,000 FRBs
occur in the sky every day, their nature is one of the most topical questions in astrophysics
today (Petroff, et al., 2019; Cordes and Chatterjee, 2019).
Zeroing in on the First Repeater
Given the short intrinsic duration of the source’s radio flashes, we can measure the disper-
sion delay that the radio waves suffer. The delay is proportional to the column density of
electrons from the source to the observer, a quantity called dispersion measure (DM). Tak-
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GeminiFocus
January 2020