Once again, galaxies appear to be surprisingly mature shortly after the beginning of the universe

A young galaxy with its catchy name A1689-zD1 has experts in galaxy formation. Recent observations show that this galaxy, seen as it would appear only 700 million years after the Big Bang, is larger than initially thought, with large flows of hot gas from its core, and a halo of cold gas emanating from its outer edge. A1689-zD1 is representative of young “ordinary” galaxies (as opposed to “mega” galaxies), and the new observations suggest that the adolescence of regular galaxies may be more turbulent than previous models suggest.

A1689-zD1 was first observed in 2007 by the Hubble Space Telescope, at which time it was a contender for the most distant galaxy yet discovered (a record that has been exceeded several times, most recently in April 2022). In fact, it’s so far away that the only reason it’s possible to get such a good image at all is because it’s conveniently located behind a much closer galaxy, the interaction of its gravity with spacetime creating a lensing effect, magnifying The distance is A1689- zD1 behind it. The Spitzer Space Telescope was able to observe the galaxy alongside Hubble, but the clearest images of the galaxy were obtained within the Large Millimeter/ Submillimeter Atacama Array (ALMA), which specializes in wavelengths invisible to the naked eye and is well suited to very distant objects. .

ALMA data tells a story buried in detail that Hubble and Spitzer couldn’t see.

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β€œThe carbon emissions in A1689-zD1 are much more extended than observed with the Hubble Space Telescope, and this may mean that early galaxies are not as small as they appear,” says Seiji Fujimoto, a postdoctoral fellow at the Niels Bohr Institute. Indeed, greater than we previously thought, this will have a significant impact on the theory of galaxy formation and its evolution in the early universe.”

ALMA Observatory located in the Atacama Desert in Chile. Credit: ESO/C. Bontone (Wikimedia Commons)

Besides the surprising size of A1689-zD1, it also appears to be undergoing a surprisingly high level of star formation in a halo of carbon gas surrounding the galaxy, although this gas may also be a sign of a galactic merger that occurred during the early stages of the galaxy. galaxy formation. Either way, it points to an unexpectedly dynamic early stage of galactic formation.

Near the galactic core, the team also saw signs of hot ionized gas that typically represents highly energetic events such as supernova explosions or powerful jets from the black hole’s accretion disk. This outflow of hot gas may be related to the cold gas halo, and this has piqued the researchers’ interest. At the very least, they weren’t expecting to see it in such a young galaxy. “We’ve seen this kind of gas halo emission extending from galaxies that formed later in the universe, but seeing it in such an early galaxy means that this kind of behavior is universal even in the most modest galaxies that formed most stars in the early universe,” says Darach Watson. Associate Professor at the Niels Bohr Institute. “Understanding how these processes occur in such a young galaxy is critical to understanding how star formation occurred in the early universe.”

A1689-zD1, a star-forming galaxy located in the constellation Virgo, as seen by ALMA. A gravitational lens makes the young galaxy appear nine times brighter. Credit: ALMA (ESO/NAOJ/NRAO) / H. Akins (Grenell College), B. Saxton (NRAO/AUI/NSF).

Of course, this one observation is unlikely to lead to a rewrite of textbooks yet. Researchers will continue to monitor the early universe for galaxies of similar age, to determine whether A1689-zD1 is typical in its size and activity, or whether it is exotic.

The James Webb Space Telescope, like ALMA, which is well suited for observing small galaxies at this distance, should provide a larger sample for study soon. It is due to go online later this summer β€” although it will also rely on some chance gravitational lensing to find and study the oldest galaxies.

You can watch the full press release here, and read the introductory version on ArXiv.

Featured image: Artist’s rendering of the A1689-zD1. Reaching far beyond the galactic center, shown here in pink, is an abundant halo of cold carbon gas. For scientists, this unusual feature suggests that the galaxy may be much larger than previously thought and that the early stages of normal galaxy formation may be more active and dynamic than expected. To the top left and bottom right are outflows of hot ionized gas pushing outward from the galactic center, shown here in red. Scientists think it’s possible that these outflows may have something to do with it, though they don’t yet know what they’re doing, with cold carbon gas in the galaxy’s outer reaches. Credit: ALMA (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)