Using the Magellan telescopes in Chile, Italian astronomers observed a giant galaxy cluster known as Abell 2744, called the Pandora cluster. The results of the surveillance campaign are presented in a paper published on the preprint server on February 13. arXivProvide more information about the characteristics of this cluster.

Galaxy clusters contain up to a thousand galaxies bound together by gravity. They are formed by the accumulation of mass and the collapse of smaller substructures and are the largest known gravitationally bound structures in the universe. Therefore, they can serve as excellent laboratories for studies of galaxy evolution and cosmology.

Located approximately 4 billion light-years from Earth, the Pandora Cluster is a giant cluster of galaxies approximately 4 trillion times the mass of the Sun. This appears to be the result of the simultaneous accretion of at least four separate small galactic clusters over a period of 350 million years.

Previous observations of the Pandora cluster have shown it to exhibit one of the most complex mergers ever detected, seen in both radio and X-ray data. The cluster also attracted the attention of a group of astronomers led by Davide Abriola of the University of Milan in Italy; they decided to investigate it with MegaCam, a large mosaic CCD camera on one of the Magellan telescopes.

“In this paper, we present an improved WL (weak lensing) analysis of the Abell 2744 galaxy cluster using deep multispectral Magellan/MegaCam data covering an approximately 31′ × 33′ field of view… For our study, we implemented a pipeline-based reconstruction of the PSF. For configuration, two new programs are used: mccd and ngmix. [функції розповсюдження точок] and shape measurements, respectively,” the researchers write in the paper.

First, new observations showed that the Pandora cluster has an estimated total mass of approximately 2.56 quadrillion solar masses; It is 7.66 million light-years away from the brightest galaxy cluster in the southwest. This makes it one of the largest galaxy clusters discovered to date.

The reconstructed total surface mass distribution revealed the presence of three high-density peaks, substructures, in the inner core of the Pandora cluster. One, with higher intensity and a signal-to-noise ratio of 14.0, is located in the southeastern part of the cluster, very close to the cluster’s brightest galaxy, while the other two are in the northwestern corner.

According to the authors of the paper, these results confirm that the cluster did not relax, as previous studies suggested, but went through a complex merger process. They added that this was also confirmed by comparison with a new, high-precision, strong lensing analysis of the central region of the cluster based on data from the James Webb Space Telescope (JWST).