Photo: Jeffrey Chan, UC Riverside
Astronomers of the International group under the leadership of Ryan Foltz (Foltz, Ryan) University of California, riverside (USA) have discovered why some galaxies that fall into galaxy clusters, comes the mysterious cessation of the formation of new stars. About it reported in a press release on EurekAlert!.
Scientists have discovered how the process of attenuation takes place in galaxies over most of the history of the Universe. This allowed the astronomers to determine the most likely causes of the cessation of star formation in galaxy clusters.
For example, each galaxy within the cluster, brings with it a certain amount of cold gas, which is the “raw material” for new stars. A hot dense gas which exists inside the cluster, knocks galaxy cold gas, terminating star formation.
Another possible mechanism is the cessation of the flow of cold gas in the galaxy, caught in the congestion. Finally, the energy released during the formation of stars, may facilitate the outflow of cold gas from the galaxy. In the latter scenario, the gas leaving the star system, which ensures a much more rapid cessation of formation of new stars, than by the action of other mechanisms.
The researchers analyzed data on hundreds of galaxy clusters, detected in remote regions of the Universe. The observations were carried out during 10 nights at the Keck Observatory (Hawaii) and 25 nights at the Observatory Gemini (Hawaii and Chile).
It turned out that the aging of the Universe, the galaxies need more time in order to stop the processes of star formation. Currently, it takes five billion years, but in the early Universe it took 1.1 billion years. This indicates that the main reason for the cessation of the birth of stars in massive galaxies is the ejection of cold gas hot. However, in a small galaxies main role can be played by other mechanisms.
Video, photo All from Russia.