The most distant rotating galaxy hails from 13.3
billion years ago

The
galaxy started spinning just 500 million years after the Big Bang


 

A galaxy about 13.3 billion light-years away
(inset in this image of a galaxy cluster from the Hubble Space Telescope and
the Atacama Large Millimeter/submillimeter Array) is the most distant galaxy to
show signs of rotation.

ALMA/ESO, NAOJ AND NRAO; NASA, ESA HUBBLE SPACE TELESCOPE;
W. ZHENG/JHU, M. POSTMAN/STSCI; THE CLASH TEAM; T. HASIMOTO ET AL/NATURE 2018

 

There is a galaxy
spinning like a record in the early universe — far earlier than any others have
been seen twirling around.

Astronomers have spotted signs of rotation in the galaxy MACS1149-JD1, JD1 for short, which sits so far away that its light takes 13.3 billion years to reach Earth. “The galaxy we analyzed, JD1, is the most distant example of a rotational galaxy,” says astronomer Akio Inoue of Waseda University in Tokyo.

The origin of the
rotational motion in galaxies is closely related to a question: how galaxies
like the Milky Way formed,” Inoue says. “So, it is interesting to find the onset
of rotation in the early universe.”

JD1
was discovered in 2012. Due to its great distance from Earth, its light had
been stretched, or redshifted, into longer wavelengths, thanks to the expansion
of the universe. That redshifted light revealed that JD1 existed just 500
million years after the Big Bang.

Astronomers
used light from the entire galaxy to make that measurement. Now, using the
Atacama Large Millimeter/submillimeter Array in Chile for about two months in
2018, Inoue and colleagues have measured more subtle differences in how that
light is shifted across the galaxy’s disk. The new data show that, while all of
JD1 is moving away from Earth, its northern part is moving away slower than the
southern part. That’s a sign of rotation,
the researchers report in the July 1 
Astrophysical Journal Letters.

JD1
spins at about 180,000 kilometers per hour, roughly a quarter the spin speed of
the Milky Way. The galaxy is also smaller than modern spiral galaxies. So JD1
may be just starting to spin, Inoue says.

The James Webb Space Telescope will
observe JD1 in the next year to reveal more clues to how that galaxy, and
others like ours, formed (
SN: 10/6/21).  

 Questions or
comments on this article? E-mail us   at feedback@sciencenews.org

  



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