Results of the summarizing process for the arXiv paper: 2109.10384v1

A recent study has found that star formation in half of massive galaxies was halted by the time the Universe was three billion years old. The researchers discovered that very low amounts of molecular gas were responsible for this quenching, at least in some cases. Other potential factors include morphological gas stabilization, shock heating, or activity associated with accretion onto a central supermassive black hole. Previous studies on quenching by gas depletion have been limited by insufficiently sensitive upper limits or the use of stacked emission, which can lead to issues with averaging. To address these limitations, the researchers conducted 1.3mm observations of dust emission from six strongly lensed galaxies where star formation had been quenched. These galaxies were magnified up to a factor of 30. Out of the six galaxies studied, four were undetected in dust emission. The researchers estimated an upper limit on the dust mass for these galaxies to be 0.0001 times the stellar mass. By proxy (assuming a Milky Way molecular gas-to-dust ratio), this corresponds to 0.01 times the stellar mass in molecular gas - two orders of magnitude less than what is seen in star-forming galaxies at similar redshifts. While it remains challenging to extrapolate from such small samples, these observations provide evidence that gas depletion plays a role in halting star formation in a fraction of high-redshift galaxies and shed light on the mechanisms behind galaxy evolution and star formation throughout cosmic history. The findings have been published online by Nature and offer valuable insights into how and why star formation ceases in certain galactic environments.

• Star formation in half of massive galaxies halted by the time the Universe was three billion years old
• Very low amounts of molecular gas responsible for quenching in some cases
• Other potential factors include morphological gas stabilization, shock heating, or activity associated with accretion onto a central supermassive black hole
• Previous studies limited by insufficiently sensitive upper limits or use of stacked emission
• Researchers conducted 1.3mm observations of dust emission from six strongly lensed galaxies where star formation had been quenched
• Four out of six galaxies undetected in dust emission
• Upper limit on dust mass estimated to be 0.0001 times the stellar mass, corresponding to 0.01 times the stellar mass in molecular gas (two orders of magnitude less than star-forming galaxies at similar redshifts)
• Gas depletion plays a role in halting star formation in a fraction of high-redshift galaxies
• Findings shed light on mechanisms behind galaxy evolution and star formation throughout cosmic history

The Quenching of Star Formation in Massive Galaxies

Recent research has uncovered a new insight into the quenching of star formation in massive galaxies. A study published online by Nature found that half of massive galaxies had their star formation halted by the time the Universe was three billion years old, and that very low amounts of molecular gas were responsible for this quenching in some cases.

What is Quenching?

Quenching is a process whereby star formation is abruptly stopped or reduced due to an external factor. It can be caused by a variety of factors, including morphological gas stabilization, shock heating, or activity associated with accretion onto a central supermassive black hole. Previous studies on quenching have been limited by insufficiently sensitive upper limits or the use of stacked emission which can lead to issues with averaging.

The Study

To address these limitations, researchers conducted 1.3mm observations of dust emission from six strongly lensed galaxies where star formation had been quenched. These galaxies were magnified up to a factor of 30. Out of the six galaxies studied, four were undetected in dust emission and it was estimated that an upper limit on the dust mass for these galaxies was 0.0001 times the stellar mass - two orders of magnitude less than what is seen in star-forming galaxies at similar redshifts (assuming a Milky Way molecular gas-to-dust ratio).

Implications

While it remains challenging to extrapolate from such small samples, these observations provide evidence that gas depletion plays an important role in halting star formation in some high-redshift galaxies and shed light on mechanisms behind galaxy evolution and star formation throughout cosmic history. The findings offer valuable insights into how and why star formation ceases in certain galactic environments and could help us better understand our own universe today as well as its future evolution over time.