Galaxies

The two quasars of SDSS J0749+2255 as seen by Hubble (Image NASA, ESA, Yu-Ching Chen (UIUC), Hsiang-Chih Hwang (IAS), Nadia Zakamska (JHU), Yue Shen (UIUC))

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An article published in the journal “Nature” reports the discovery of a pair of merging galaxies cataloged as SDSS J0749+2255 which has the peculiarity of hosting a double quasar. A team of researchers led by the University of Illinois at Urbana-Champaign used various ground-based and space telescopes to study SDSS J0749+2255 to obtain observations detailed enough to resolve the two quasars, both of which are extremely bright. The difficulty in these observations is also given by the fact that this pair is very distant and we see it as it was when the universe was about three billion years old and the distance between the two supermassive black holes that power their respective quasars is only about ten thousand light-years.

Galaxy Z 229-15 (Image ESA/Hubble & NASA, A. Barth, R. Mushotzky)

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An image captured by the Hubble Space Telescope shows galaxy Z 229-15. A combination of the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) instruments with three different filters was used to obtain observations including ultraviolet, optical, and near-infrared emissions. Z 229-15 is a galaxy that defies simple classification criteria because it has a set of features not normally found together. The result is that it fits different definitions showing how sometimes classes and subclasses of galaxies don’t have precise boundaries but can overlap making different classifications valid.

The galaxy protocluster around the Spiderweb Galaxy with gas from the intracluster medium in blue (Image ESO/Di Mascolo et al.; HST: H. Ford)

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An article published in the journal “Nature” reports the results of a study on the formation of a primordial galaxy cluster, observed in its early stages. A team of researchers led by Luca Di Mascolo of the University of Trieste, Italy, used the ALMA radio telescope to study the intracluster medium, the gas that permeates the protocluster around the galaxy MRC 1138-262, known as the Spiderweb Galaxy, and has an overall mass greater than the mass of the galaxies that form it. Observations of the intracluster medium in forming clusters are scarce, making those observations precious to understand the formation processes of galaxy clusters.

A scheme of the passage from the universe full of neutral hydrogen and dark to the bright one following the epoch of reionization

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An article published in the journal “Astronomy & Astrophysics” reports the identification of a group of primordial galaxies that could be among the ones that contributed to the reionization of the universe, making it go from dark to bright. A team of researchers coordinated by the Italian National Institute of Astrophysics used observations conducted with the James Webb space telescope within the GLASS-JWST program to study 29 very distant and therefore ancient galaxies. The examination of those galaxies’ physical characteristics led the researchers to conclude that 80% of them contributed significantly to reionization.

The jellyfish galaxy JO201 (Image ESA/Hubble & NASA, M. Gullieuszik)

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An article in publication and an article under peer-review in “The Astrophysical Journal” report various aspects of a study of 6 so-called jellyfish galaxies. A team of researchers used various instruments to examine them and try to understand the processes taking place in the “tentacles” generated by the gas stripped from those galaxies during the passage within a galaxy cluster. In that space, there’s intergalactic plasma that generates a pressure that caused that gas loss in a process called ram pressure stripping. An image of the jellyfish galaxy cataloged as JO201 captured by the Hubble Space Telescope was published by ESA.