Since its launch nearly two years ago, the James Webb Space Telescope (JWST) has produced countless fascinating images of the universe and provided new insights into how it evolves. In particular, the telescope’s instruments are optimized to study the cosmological period known as the cosmic dawn, 50 million to one billion years after the Big Bang, when the first stars, black holes, and galaxies formed in the universe. But astronomers are also getting a better look at the next period, the cosmic noon that lasts 2 to 3 billion years after the Big Bang.

During this time, the first galaxies grew significantly, most of the stars in the universe were formed, and supermassive black holes (SMBHs) evolved into incredibly bright quasars. Scientists wanted to take a better look at galaxies from this period to see how SMBHs affected star formation in young galaxies.

Using near-infrared data obtained by Webb, an international team of astronomers made detailed observations of more than 100 galaxies coinciding with cosmic noon 2 to 4 billion years after the Big Bang. The work is published on the prepress server arXiv.

The research was led by Rebecca L. Davies, a research fellow at the Center for Astrophysics and Supercomputing (CAS) at Swinburne University of Technology and the ARC Center of Excellence for All-Sky Astrophysics in 3D (ASTRO 3D).

He was joined by researchers from the Harvard-Smithsonian Center for Astrophysics (CfA), the Leibniz Institute for Astrophysics (AIP), the Gravity and Space Institute (LGC), and Penn State University’s Computer and Data Institute (ICDS). , the Kavli Institute for Cosmology and the Cavendish Laboratory at the University of Cambridge, Columbia University Astrophysics Laboratory, and more.

A preprint of their article is being considered for publication Monthly Notices of the Royal Astronomical Society. As they point out in their paper, understanding the mechanism(s) responsible for stopping star formation in massive galaxies is key to understanding how galaxies evolve. When galaxies stop forming stars, they actually stop growing and changing and become static and “old.”

Dr. As Davis told Universe Today via email, quenching is a fundamental process in the life cycle of galaxies that astronomers still do not fully understand.

Over the past decade, there have been many large galaxy surveys that have improved our understanding of the flows during cosmic noon, when the feedback from the SMBH is expected to be most active. As a result, a general consensus has emerged that everything originates from active galactic nuclei (AGN) (aka quasars) powered by SMBHs at their cores.

According to this consensus, strong AGN emission expels cold gas while also heating the gas reservoir in the galactic halo. This prevents the star-forming gas from cooling and accumulating again to replenish the reservoir.

As Dr Davies explains: “It is well established that active galactic nuclei (supermassive black holes consuming large amounts of gas) can cause outflows from galaxies. The most powerful AGNs give rise to very large sources that are likely to blow all gas away from their hosts in a relatively “short time.” “over a period of time (in astronomical terms!) it leads to the destruction of galaxies and the cessation of star formation. However, more ‘normal’ AGNs appear to produce much weaker outflows, and it is debated whether these outflows are strong enough to suppress star formation.”

There is plenty of indirect evidence to suggest that massive galaxies extinguish the activity of supermassive black holes, but direct evidence for this is still lacking.

“The picture is complicated because the outputs are ‘multiphase’; they contain gas with a wide range of temperatures and densities that emit light across the electromagnetic spectrum, from X-rays to radio waves,” Davis said. he added. “Most of our observations focus on ionized gas because it’s the easiest to see. But we believe it only accounts for 1% of leaks, so we’re only clearing the tip of the iceberg when it comes to mass leaks.”

For their study, the team relied on data obtained with the Webb Slit-Free Near Infrared Spectrograph (NIRSpec) of 113 galaxies selected from the Blue Jay survey. This study was part of the JWST Cycle 1 General Observations (GO 1810), which investigated the prevalence and typical properties of neutral gas outflows in the cosmic Kuhn.

The sensitivity and high resolution of the NIRSpec instrument allowed Daniels and his colleagues to study the outflow of cold neutral gas in these selected galaxies in ways not previously possible.

As he explains, “We found outflows of cold neutral gas caused by AGN activity in about 1/4 of the large galaxies we observed. These neutral outflows are at least as large as previously measured ionized outflows, and in some cases the neutral outflows are 10 to 100 times larger. More importantly, “Outflows are observed in galaxies at different stages of evolution: Some galaxies are actively forming stars, while others are almost extinct. In dying galaxies, outflows remove gas 300 times faster than the rate at which they form stars.”

These observations support the theory that AGNs are responsible for “turning off” star formation when galaxies reach a certain age. This could improve our understanding of galaxy evolution by measuring the effects of the AGN at a key stage of galaxy evolution.

While ongoing Cosmic Dawn observations provide glimpses of galaxies emerging from their cradles (cosmic dark ages), this study offers detailed information about what they look like as they progress towards maturity. The cumulative result, Davis said, is a more comprehensive understanding:

“Our results show that AGN-driven flows can rapidly remove cold gas from galaxies, depriving them of the fuel needed for star formation. These powerful flows are not uncommon, but appear to be relatively frequent among large, distant galaxies. Therefore, the removal of cold gas by AGN-driven flows “It may be a common reason for the rapid cessation of star formation in distant massive galaxies.” Source