By Kavli Institute for the Physics and Mathematics of deep space
April 27, 2023
A simulated visualization illustrates the situation of large-scale heating around a galaxy protocluster, using information from supercomputer simulations. The blue color suggests cooler gas, which situated in the outer regions of the protocluster and the filaments linking the hot gas with other structures. This figure compares observed hydrogen absorption in area of the COSTCO-I galaxy protocluster (top panel), compared with the anticipated absorption offered the existence of the protocluster as calculated from computer simulations. Galaxy protoclusters in the remote universe such as this are routinely found, the team found something unusual when they checked ultra-violet spectra covering COSTCO-I utilizing the 10.3-meter size Keck-I Telescope at the W.M. Keck Observatory on Maunakea, Hawaii.
Astronomers normally look for protoclusters in galaxies or the intergalactic medium to discover them.
A simulated visualization depicts the situation of massive heating around a galaxy protocluster, utilizing data from supercomputer simulations. This is believed to be a comparable situation to that observed in the COSTCO-I protocluster. The blue color suggests cooler gas, which located in the outer regions of the protocluster and the filaments linking the hot gas with other structures.
A new research study published in The Astrophysical Journal Letters reports that a team of worldwide scientists, led by the Kavli Institute for the Physics and Mathematics of deep space (Kavli IPMU), have actually discovered the earliest indications of particular portions of the universe that were warmed to temperature levels comparable to that of the intergalactic gas medium, where most of atoms in the universe presently reside.
The huge majority of all atoms in the universe, roughly 90%, can be found in the intergalactic gas that fills the areas in between noticeable galaxies. This intergalactic medium is currently in a intricate and hot state, with temperature levels varying from 100,000 degrees Celsius to over 10 million degrees Celsius, referred to by scientists as the “Warm-Hot Intergalactic Medium” (WHIM).
However, more than 10 billion years back, a time when galaxies in deep space were at the peak of forming their stars, the majority of the intergalactic medium existed at relatively cooler temperature levels of less than 10,000 degrees Celsius, developing a more foreseeable and stable stage.
A global group of researchers led by Kavli IPMU graduate trainee Chenze Dong and Project Assistant Professor Khee-Gan Lee have determined the outermost spot of the universe warmed up to temperatures more particular of todays WHIM at a time when the universe was just 3 billion years old. This area is a giant aggregation of galaxies referred to as COSTCO-I, a galaxy protocluster with a total mass of over 400 trillion times the mass of the Sun, and spanning numerous million light-years across, which was also found by Lee and a team of scientists at Kavli IPMU in 2022.
This figure compares observed hydrogen absorption in area of the COSTCO-I galaxy protocluster (leading panel), compared with the expected absorption offered the existence of the protocluster as computed from computer simulations. The black dots in the figure show where astronomers have identified galaxies in that area. Galaxy protoclusters in the remote universe such as this are regularly found, the group found something odd when they examined ultra-violet spectra covering COSTCO-I utilizing the 10.3-meter size Keck-I Telescope at the W.M. Keck Observatory on Maunakea, Hawaii.
Typically, the large mass and size of galaxy protoclusters would cast a big shadow when seen at the specific wavelength of 121.6 nanometers, triggered by the absorption by the neutral hydrogen related to the protocluster gas.
No absorption shadow was discovered at the location of COSTCO-I.
” We were surprised at the absence because hydrogen absorption is one of the typical methods to browse for galaxy protoclusters, and other protoclusters near COSTCO-I do show this absorption signal”, said Dong.
The lack of neutral hydrogen tracing the protocluster shows the gas in the protocluster must be heated to possibly a million degrees above the cool state expected for the intergalactic medium at that time in deep space.
” If we think of the contemporary intergalactic medium as a gigantic cosmic stew that is frothing and boiling, then COSTCO-I is probably the first bubble in the far-off past that astronomers have observed throughout an era while many of the pot was still cold”, said Lee.
” The homes and origin of the WHIM stay among the biggest questions in astrophysics right now, and to be able to look at one of the early heating websites of the WHIM will assist reveal the systems that triggered the intergalactic gas to boil up into the present-day froth. There are a couple of possibilities for how this can happen, however it might be either from gas heating up as they collide with each other throughout gravitational collapse, or giant radio jets might be pumping energy from supermassive black holes within the protocluster,” he said.
Astronomers normally look for protoclusters in galaxies or the intergalactic medium to discover them. The future PFS study will be able to search for more such protoclusters, like COSTCO-I, and reveal their advancement,” said co-author and JSPS Overseas Research Fellow Rieko Momose.
The intergalactic medium represents the gas tank feeding raw material to galaxies, and hot gas behaves in a different way from cold gas in how quickly they can stream into galaxies to form stars. Having the ability to directly study the development of the WHIM in the early universe would permit astronomers to develop a meaningful image of galaxy development and the lifecycle of gas that feeds it.
Kavli IPMU astronomers are currently heavily included in the development of a powerful brand-new multi-object spectrograph for the 8.2 m Subaru Telescope on Maunakea, understood as the Subaru Prime Focus Spectrograph (PFS). With Subaru PFS, astronomers will have the ability to draw up 40 times bigger volumes than in the existing study and study the gas properties in hundreds of galaxy protoclusters.
Recommendation: “Observational Evidence for Large-scale Gas Heating in a Galaxy Protocluster at z = 2.30” by Chenze Dong, Khee-Gan Lee, Metin Ata, Benjamin Horowitz and Rieko Momose, 14 March 2023, The Astrophysical Journal Letters.DOI: 10.3847/ 2041-8213/ acba89.