Sky & Telescope - September 2023 - 19

gravitational-wave sources, and even to track them down to
particular galaxies. " Eventually, this will tell astronomers
more about the evolution and merger history of galaxies.
But DSA-2000's main job, using up 65% of the available
observing time, will be to carry out repeated radio surveys of
the entire visible sky, observing each 11-square-degree field
for about 15 minutes before moving on to the next. Thanks to
the large field of view, the array's survey speed will be about
a thousand times higher than the VLA's, and some 150 times
higher than MeerKAT's. And thanks to the huge sensitivity,
Hallinan expects the new facility to detect at least 1 billion
discrete sources, including radio galaxies and active galactic
nuclei, providing astronomers with a better understanding of
cosmic history.
In the local universe, 1,420-MHz observations will reveal
the distribution and dynamics of neutral hydrogen gas in tens
of thousands of galaxies - something that has never been
possible before, according to Walter. " In the past, we could
only observe one object at one frequency at a time, " he says.
" With DSA-2000, it's like getting everything in one shot. "
Finally, DSA-2000 will be a discovery engine for many
kinds of transients. By surveying the dynamic radio sky three
or four times per year, it will not only find countless FRBs but
also millions of other short-duration phenomena, like remote
supernovae, flares from quasars, and tidal disruption events,
in which stars are devoured by supermassive black holes.
Meanwhile, the array is flexible enough to quickly respond
to discoveries from other facilities such as gamma-ray satellites,
gravitational-wave detectors, and the upcoming Vera
Rubin Observatory, searching for and studying the radio
counterparts of a wide variety of astronomical transients.
" Most of these haven't really been studied very well so far, "
says Scott Ransom (National Radio Astronomy Observatory),
another member of the DSA-2000 science advisory committee.
" Since we'll be imaging a big chunk of the sky at all
times, we're effectively carrying out a sky survey for radio
transients. This is really going to be the radio counterpart of
the Rubin Observatory. "
Although DSA-2000 is not yet fully funded, Hallinan and
his team are confident that their ambitious plans will be
realized. The National Science Foundation (NSF) has already
funded the $6.3 million DSA-110 prototype array, and the
DSA-2000 team will request the first tranche of construction
funding from the NSF's Mid-scale Research Infrastructure
program later this year. Additional support has come from
Schmidt Futures, a philanthropic initiative by former Google
CEO Eric Schmidt and his wife, Wendy, as well as from
Caltech. " We are open to other partnerships, " says Jameson.
Around the time you're reading this, the first prototype
antennas of DSA-2000 should be completed. Construction of
the array, possibly in Hot Creek Valley in central Nevada, is
expected to commence in the summer of 2024, and the first
science results could already come in by 2026 or 2027. " It's
not like we need to build 2,000 antennas before pushing the
start button, " says Walter. " Even with 100 or 200 antennas,
we can be in business already. "
Hallinan, for one, can't wait. " We're building on the legacy
of other radio observatories, " he says, " but especially in terms
of survey power, DSA-2000 will be unprecedented. "
¢ S&T Contributing Editor GOVERT SCHILLING travels the
world in search of astronomy wonders. Next time he takes a
road trip to the American Southwest, the DSA-2000 array will
definitely be on his itinerary.
sk yand tele scope .o r g * SEPTEMBER 2023 19
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