The Atacama Large Millimeter/submillimeter Array (ALMA) is an international astronomy facility that detected a large reservoir of hot gas in the still-forming galaxy cluster around the Spiderweb galaxy, the most distant detection of such hot gas yet. Galaxy clusters, as the name suggests, host a large number of galaxies and contain a vast “intracluster medium” (ICM) of gas that considerably outweighs the galaxies themselves. The team of researchers led by Luca Di Mascolo at the University of Trieste, Italy, used ALMA to detect the ICM of the Spiderweb protocluster through the thermal Sunyaev-Zeldovich (SZ) effect. The team’s findings were presented in the paper “Forming intracluster gas in a galaxy protocluster at a redshift of 2.16” and are published in ESO’s open-access journal. The discovery of the ICM in distant protoclusters allows astronomers to catch these clusters in the early stages of formation and gain a better understanding of the earliest phases of formation of the ICM. ALMA’s unique capabilities have paved the way for future discoveries of the largest structures in the Universe.
Astronomers Discover Hot Gas Reservoir in the Early Universe’s Protocluster Around Spiderweb Galaxy Using ALMA
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered a large reservoir of hot gas in the early Universe’s protocluster around the Spiderweb galaxy. This is the most distant detection of such hot gas yet. The Spiderweb protocluster was located at an epoch when the Universe was only 3 billion years old. The results of the study, published in Nature, reveal just how early galaxy clusters, some of the largest objects known in the Universe, begin to form.
Galaxy clusters host a large number of galaxies and contain a vast intracluster medium (ICM) of gas that weighs considerably more than the galaxies themselves. Most of the mass in the protocluster around the Spiderweb galaxy does not reside in the galaxies that can be seen in the centre of the image, but in the gas known as the ICM. The ICM had only been studied in fully-formed nearby galaxy clusters, so the detection of the ICM in distant protoclusters would allow astronomers to catch these clusters in the early stages of formation.
Luca Di Mascolo, a researcher at the University of Trieste, Italy, and the first author of the study, led the team who was keen to detect the ICM in a protocluster from the early stages of the Universe. Galaxy clusters are so massive that they can bring together gas that heats up as it falls towards the cluster. Elena Rasia, a researcher at the Italian National Institute for Astrophysics (INAF) in Trieste, Italy, and co-author of the study, explains that cosmological simulations have predicted the presence of hot gas in protoclusters for over a decade, but observational confirmation has been missing. Pursuing such key observational confirmation led the team to carefully select one of the most promising candidate protoclusters, the Spiderweb protocluster.
The discovery of a large reservoir of hot gas in the Spiderweb protocluster indicates that the system is on its way to becoming a proper, long-lasting galaxy cluster rather than dispersing. The ALMA observations revealed a hot gas cloud that extends over several hundred thousand light-years, with a total gas mass of around 10 trillion times that of the Sun. The hot gas in the ICM is shown as an overlaid blue cloud in the image of the protocluster around the Spiderweb galaxy.
ALMA’s Thermal Sunyaev-Zeldovich Effect Used to Detect ICM in the Spiderweb Protocluster
The team led by Luca Di Mascolo at the University of Trieste, Italy, has detected the intracluster medium (ICM) of the Spiderweb protocluster using the thermal Sunyaev-Zeldovich (SZ) effect. This effect happens when light from the cosmic microwave background interacts with the fast-moving electrons in the hot gas and gains a bit of energy, changing its colour or wavelength. By measuring these shadows on the cosmic microwave background, astronomers can infer the existence of the hot gas, estimate its mass, and map its shape.
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that the Spiderweb protocluster contains a vast reservoir of hot gas at a temperature of a few tens of millions of degrees Celsius. The mass of the hot gas found in this new study outweighs the cold gas that had previously been detected in this protocluster by thousands of times. The detection of a large reservoir of hot gas in the Spiderweb protocluster shows that it is expected to turn into a massive galaxy cluster in around 10 billion years, growing its mass by at least a factor of ten.
Tony Mroczkowski, a co-author of the paper and researcher at ESO, explains that the hot thermal component of this system will destroy much of the cold component as the system evolves, and this is a delicate transition. The results provide observational confirmation of long-standing theoretical predictions about the formation of the largest gravitationally bound objects in the Universe.
ALMA’s unparalleled resolution and sensitivity make it the only facility currently capable of measuring these shadows for the distant progenitors of massive clusters, says Di Mascolo. These findings lay the groundwork for synergies between ALMA and ESO’s upcoming Extremely Large Telescope (ELT), which will revolutionize the study of structures like the Spiderweb.
The ELT, along with its state-of-the-art instruments like HARMONI and MICADO, will peer into protoclusters and provide crucial glimpses into the assembly of some of the largest structures in the early Universe. This discovery of the ICM in distant protoclusters will allow astronomers to catch these clusters in the early stages of formation and gain a better understanding of the earliest phases of formation of the ICM.
This research, presented in the paper “Forming intracluster gas in a galaxy protocluster at a redshift of 2.16” and to appear in Nature, paves the way for future discoveries of the largest structures in the Universe.
ALMA: An International Astronomy Facility
The Atacama Large Millimeter/submillimeter Array (ALMA) is an international astronomy facility that is a partnership of ESO, the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST), and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning, and operation of ALMA.
The team of researchers led by Luca Di Mascolo at the University of Trieste, Italy, used ALMA to detect the intracluster medium (ICM) of the Spiderweb protocluster through the thermal Sunyaev-Zeldovich (SZ) effect. The team’s findings were presented in the paper “Forming intracluster gas in a galaxy protocluster at a redshift of 2.16” and are published in ESO’s open-access journal.
ALMA’s unique capabilities in measuring the shadows on the cosmic microwave background for the distant progenitors of massive clusters have led to the discovery of the ICM in distant protoclusters, allowing astronomers to catch these clusters in the early stages of formation and gain a better understanding of the earliest phases of formation of the ICM. This discovery paves the way for future discoveries of the largest structures in the Universe.
Don’t miss interesting posts on Famousbio
