Why Galaxies Clusters and Great Voids in the Universe? Astronomers Rethink Quasar Environment
In the Universe, galaxies are not distributed uniformly. There are some places, known as clusters, where dozens or hundreds of galaxies are found close together. Other galaxies are isolated. To determine how and why clusters formed, it is critical to investigate not only mature galaxy clusters as seen in the present Universe but also observe protoclusters, galaxy clusters in the process of forming.
Because the speed of light is finite, observing distant objects allows us to look back in time. For example, the light from an object 1 billion light-years away was actually emitted 1 billion years ago and has spent the time since then traveling through space to reach us. By observing this light, astronomers can see an image of how the Universe looked when that light was emitted.Stars indicate quasars and bright (faint) galaxies at the same epoch are shown as circles (dots). The galaxy overdensity with respect to the average density is shown by the contour. The pair members are associated with high density regions of galaxies.
Credit: NAOJ
In order to understand protoclusters in the distant Universe a larger observational sample was needed. A team including astronomers from the National Astronomical Observatory of Japan, the University of Tokyo, the Graduate University for Advanced Studies, and other institutes is now conducting an unprecedented wide-field systematic survey of protoclusters using the Subaru Telescope’s very wide-field camera, Hyper Suprime-Cam (HSC). By analyzing the data from this survey, the team has already identified nearly 200 regions where galaxies are gathering together to form protoclusters in the early Universe 12 billion years ago.
The team also addressed the relationship between protoclusters and quasars. The team sampled 151 luminous quasars at the same epoch as the HSC protoclusters and to their surprise found that most of those quasars are not close to the overdense regions of galaxies. In fact, their most luminous quasars even avoid the densest regions of galaxies. These results suggest that quasars are not a good proxy for protoclusters and more importantly, mechanisms other than galactic mergers may be needed to explain quasar activity. Furthermore, since they did not find many galaxies near the brightest quasars, that could mean that hard radiation from a quasar suppresses galaxy formation in its vicinity.
On the other hand, the team found two “pairs” of quasars residing in protoclusters. Quasars are rare and pairs of them are even rarer. The fact that both pairs were associated with protoclusters suggests that quasar activity is perhaps synchronous in protocluster environments. “We have succeeded in discovering a number of protoclusters in the distant Universe for the first time and have witnessed the diversity of the quasar environments thanks to our wide-and-deep observations with HSC,” says the team’s leader Nobunari Kashikawa (NAOJ).
“HSC observations have enabled us to systematically study protoclusters for the first time.” says Jun Toshikawa, lead author of the a paper reporting the discovery of the HSC protoclusters, “The HSC protoclusters will steadily increase as the survey proceeds. Thousands of protoclusters located 12 billion light-years away will be found by the time the observations finish. With those new observations we will clarify the growth history of protoclusters.”
Contacts and sources:
Hideaki Fujiwara
National Institutes of Natural Sciences
Source:
Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.
"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.
Please Help Support BeforeitsNews by trying our Natural Health Products below!
Order by Phone at 888-809-8385 or online at https://mitocopper.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomic.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomics.com M - F 9am to 5pm EST
Humic & Fulvic Trace Minerals Complex - Nature's most important supplement! Vivid Dreams again!
HNEX HydroNano EXtracellular Water - Improve immune system health and reduce inflammation.
Ultimate Clinical Potency Curcumin - Natural pain relief, reduce inflammation and so much more.
MitoCopper - Bioavailable Copper destroys pathogens and gives you more energy. (See Blood Video)
Oxy Powder - Natural Colon Cleanser! Cleans out toxic buildup with oxygen!
Nascent Iodine - Promotes detoxification, mental focus and thyroid health.
Smart Meter Cover - Reduces Smart Meter radiation by 96%! (See Video).