Shriharsh P. Tendulkar, on behalf of the FRB 121102 collaboration
The Host Galaxy of the Repeating
Fast Radio Burst FRB 121102
Fast radio bursts (FRBs) are a recent astronomical mystery consisting
of short, yet extremely bright, pulsar-like bursts of radio waves that
seem to traverse cosmological distances. Although they occur at a
stunning rate of 1,000 per day in the entire sky, we know little about
their origins, generation mechanisms, and, until recently, even their
distances. Using the combined forces of the Karl G. Jansky Very Large
Array in New Mexico and the Gemini North telescope in Hawai‘i, we
have localized and identified — for the first time — the host galaxy of
an FRB. Surprisingly, the host galaxy is a low-metallicity, star-forming,
dwarf galaxy ~1 billion parsecs distant, which hints at possible
similarities of this FRB host to those of superluminous supernovae and
long-duration gamma-ray bursts.
Figure 1.
The arrival of the
Lorimer burst heralded
a new era in radio
astrophysics. The
dynamic spectrum of
the pulse is shown with
frequency along the
y-axis and arrival time
along the x-axis. The
grayscale depicts the
1-bit digitized intensity.
Two thin white lines
are drawn along the
theoretical dispersion
relation to guide the
eye. The inset shows
the total intensity
profile as a function of
time after correcting
for dispersion. Figure
adapted from Lorimer
et al., 2007.
Almost exactly 10 years ago, Duncan Lorimer and his team at
West Virginia University were searching archival data from the
64-meter Parkes telescope in New South Wales, Australia, for
bright single pulses from Galactic radio pulsars. They discov-
ered a short and brilliant burst (Figure 1; now known as the
“Lorimer” burst) with a flux density or radio brightness of 30
Jansky (Jy) 1 , bright enough to saturate the detectors at Parkes
(Lorimer et al., 2007). More oddly, unlike Galactic radio pulsars,
the burst had a dispersion measure (DM; see the box, next
page) far greater than the contribution of the Milky Way along
that line of sight — 375 pc cm -3 compared to the Galactic con-
tribution of 25 pc cm -3 .
1
Jansky = 10 -23 erg/cm 2 /s/Hz.
April 2017
GeminiFocus
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