Abell 2142

The image of the galaxy indicated in the card template was obtained on August 20, 1999 by the Chandra Observatory on the ACIS spectrometer; it occupies a section of the sky with an area of ​​7.5 x 7.2 arc minutes. One can notice the large-scale manifestations of collisions of clusters. At the first stage, the front of the pressure wave was studied in detail, a bright, but relatively cold central region with a temperature of about 50 million degrees Celsius (white area in the image) was found, immersed in a large elongated cloud with a temperature of about 70 million degrees Celsius; the whole structure is immersed in a weak "atmosphere" of gas with a temperature of about 100 million degrees Celsius. The bright source in the upper left corner is an active galaxy in the cluster. ^[one]

Abell 2142 is listed in the Abell catalog of rich clusters of galaxies, first published by astronomer George Abell (1927-1983) in 1958. The cluster has a heliocentric redshift of 0.0909 (moving away from us at a speed of 27,250 km / s) and a visible magnitude of 16.0. The distance to the cluster is estimated at 380 Mpc . ^{[4] [3]}

A2142 attracts the attention of researchers because it allows us to study the dynamics of galactic mergers. Clusters of galaxies grow at the merger of smaller groups and clusters. In the process of fusion, the kinetic energy of colliding objects heats the gas between clusters, which leads to a noticeable increase in gas temperature. Such temperature variations provide information on the stage, geometry, and fusion rate. An accurate map of temperature distribution can provide information about the nature of physical processes during fusion. Previously working instruments (for example, ROSAT , ASCA ) did not possess the capabilities of the Chandra and XMM-Newton telescopes (two modern X-ray observatories) and were not able to obtain a detailed map of the area. ^[5]

Using the Chandra telescope, high-resolution temperature, density, and pressure variations were measured. According to Maxim Markevich, an astronomer from the Harvard-Smithsonian Center for Astrophysics and the head of an international group of researchers analyzing this cluster, pressure and density maps show clear boundaries, which is possible only in the case of a moving medium in the cluster. ^[one]

The observed x-ray radiation A2142 has a smooth and symmetrical distribution. This suggests that this radiation arose during fusion 1–2 billion years after the initial intersection of nuclei. If the fusion were at an early stage, an uneven distribution of x-rays could be expected. Markevich and colleagues suggest that the central galaxy (labeled G1) of a more massive cluster merged with the central galaxy (G2) of a less massive cluster. The relatively cold central region means that the heat created by the previous shock waves has passed through the central core and interacts with the surrounding gas. ^[5]