Small satellite galaxies contain less molecular gas in their centers

It is a known fact that large galaxies tend to steal gas located in the space between stars in smaller satellite galaxies. A new, recently published study found that small satellite galaxies also have less ‘molecular’ gas in their centers.

The impression of the artist that shows the growing effect of removing the pressure from the ram in removing the gas from the galaxies, which sends them to early death. Image credit: ICRAR, NASA, ESA, Hubble Heritage Team (STScI / AURA).

In the centers of galaxies, molecular gas exists as giant clouds and forms the building blocks for new stars. Thus, large galaxies remove the material needed by smaller counterparts to create new stars.

Dr. Adam Stevens, lead author of this study, is a UWA-based astrophysicist, working for the International Center for Radio Astronomy Research (ICRAR), and a member of the ARC Center for Excellence in 3-Dimensional Astronomy in the Sky (ASTRO 3D).

According to him, the study offers new systematic evidence that small galaxies generally lose a portion of their molecular gas as they approach a larger galaxy and the halo of gas surrounding a larger galaxy.

Gas is the lifeblood of the galaxy. Continuing to acquire gas, galaxies grow and form stars. Without it, galaxies stagnate. We have long known that large galaxies remove ‘atomic’ gas from the periphery of small galaxies. But so far it has not been tested with molecular gases with the same details.

Dr. Adam Stevens, Astrophysicist, ICRAR-UWA

According to ICRAR-UWA astronomer Barbara Catinella, who is also an associate professor, galaxies do not usually exist in isolation.

Most galaxies have friends. And when a galaxy moves through a hot intergalactic medium or halo of a galaxy, part of the cold gas in the galaxy is removed. This fast-acting process is known as pressure separation in ram.

Barbara Catinella, astronomer and associate professor, ICRAR-UWA

The study was an international collaboration, including scientists from the University of Maryland, the Max Planck Institute for Astronomy, the University of Heidelberg, the Harvard-Smithsonian Center for Astrophysics, the University of Bologna and the Massachusetts Institute of Technology.

Direct detection of molecular gas is extremely difficult.

Researchers in this study performed an advanced cosmological simulation and made direct predictions for the amount of atomic and molecular gas that should be detected by certain research at the Arecibo Telescope in Puerto Rico and the 30-meter IRAM Telescope in Spain.

They then compared the actual observations of the telescope with their original predictions. Surprisingly, both values ​​were very close.

Associate Professor Catinella, who led the Arecibo atomic gas research, added that a 30-meter IRAM telescope detected molecular gas in over 500 galaxies.

These are the deepest observations and the largest sample of atomic and molecular gas in the local Universe. Therefore, this was the best sample for this analysis”She added.

The team’s results fit in with earlier evidence that satellite galaxies show lower star formation rates. According to dr. According to Stevens, the removed gas first enters the space around the larger galaxy.

It could eventually rain on a larger galaxy, or it could just stay out of its environment“, He noted.

However, in most cases, a small galaxy is destined to eventually merge with a larger one.

They often survive for only one to two billion years, and then eventually merge with the central one. So, it affects the amount of gas they have as they merge, which will also affect the development of a large system. Once galaxies get big enough, they start relying on getting more matter from the cannibalism of smaller galaxies.

Dr. Adam Stevens, Astrophysicist, ICRAR-UWA

Flight through gas-taking galaxies in the IllustrisTNG simulation. Video credit: ICRAR.

Journal reference:

Stevens, ARH, and others. (2020) Molecular hydrogen in IllustrisTNG galaxies: a careful comparison of environmental signatures with local CO & SFR data. Monthly notices of the Royal Astronomical Society.