Although galaxies seem to drift through the vast cosmic sea
alone, astronomers now know that interactions between
galaxies are quite common. Some 300 million light-years
away, this galactic duo, known as Arp 282, is composed
of NGC 169 (bottom) visibly interacting with IC 1559 (top).
Wisps of gas and dust delicately link the two galaxies, a
result of the immense tidal forces at play when gravitational
goliaths stray too close. Such powerful encounters play
a vital role in how galaxies evolve in size, shape, and
structure over billions of years. And when galaxies interact,
it can even stir up dormant material within them, kick-
starting fresh bursts of star formation. So, although galactic
collisions, at first blush, may seem like cosmic calamities,
over the long run, they can actually breathe fresh life into
otherwise dimming, dying island universes. — J.P.It takes two to tango
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SCHMIDTABOUT 4,000 LIGHT-YEARS
from Earth, an astral entity is
releasing a large, minute-long f lash
of radiation three times an hour.
About every 20 minutes, the object
becomes one of the brightest radio
sources in the sky.
Its discovery, which was pub-
lished Jan. 27, 2022, in Nature, took
researchers by surprise.
“This object was appearing and
disappearing over a few hours
during our observations,” said lead
author Natasha Hurley-Walker in a
press release. “That was completely
unexpected. It was kind of spooky
for an astronomer because there’s
nothing known in the sky that
does that.”
Transients — objects that appear
to turn on and off — are not new to
researchers. However, they typically
come in one of two speeds. Slow
transients, like supernovae, appear
over a few days and disappear
within months. Fast transients, on the other hand, appear
for milliseconds or seconds at a time. Pulsars — neutron
stars that release brief but reliable f lashes of light — are one
example of fast transients.
This strange object did neither. Hurley-Walker now suspects
it may be an ultra-long period magnetar.Magnetars are the most magnetic
objects in the universe, boasting
magnetic fields that are a thousand
trillion times stronger than Earth’s.
Like their less-magnetic cousins,
pulsars, magnetars are known for
emitting bursts of radiation. But
where pulsars tend to send out
regular signals, magnetars are a bit
more erratic. And in fact, some of
this behavior is why many astrono-
mers believe magnetars are the
cause of fast radio bursts (FRBs),
sudden and intense explosions of
radiation.
But how magnetars reach a stage
where they produce FRBs is a
mystery. The missing link could be
ultra-long period magnetars.
“[These are] a type of slowly
spinning neutron star that has been
predicted to exist theoretically,”
said Hurley-Walker. “But nobody
expected to directly detect one like
this because we didn’t expect them
to be so bright. Somehow, it’s converting magnetic energy to
radio waves much more effectively than anything we’ve seen
before.”
Only more detections will tell astronomers whether they
have stumbled upon a new breed of neutron star or if this
object is one of a kind. — S.H.10 ASTRONOMY • JUNE 2022
QUANTUM GRAVITY
STRANGE FLASHES.
Radiation may be emitted
by a never-before-seen
kind of neutron star,
known as a long-period
magnetar, shown in this
artist’s concept. ICRARAstronomers find a unique neutron star