Groups & Clusters of Galaxies

Does the Gas in Galaxy Clusters Flow Like Honey?

Image of Coma Cluster
Coma Cluster
Credit: X-ray: NASA/CXC/Univ. of Chicago, I. Zhuravleva et al, Optical: SDSS

This image represents a deep dataset of the Coma galaxy cluster obtained by NASA's Chandra X-ray Observatory. Researchers have used these data to study how the hot gas in the cluster behaves, as reported in our press release. One intriguing and important aspect to study is how much viscosity, or "stickiness," the hot gas demonstrates in these cosmic giants.

Galaxy clusters are comprised of individual galaxies, hot gas, and dark matter. The hot gas in Coma glows in X-ray light observed by Chandra. Seen as the purple and pink colors in this new composite image, the hot gas contains about six times more mass than all of the combined galaxies in the cluster. The galaxies appear as white in the optical part of the composite image from the Sloan Digital Sky Survey. (The unusual shape of the X-ray emission in the lower right is caused by the edges of the Chandra detectors being visible.)

Chandra Finds Stellar Duos Banished from Galaxies

Image of Fornax Cluster
Fornax Cluster
Credit: X-ray: NASA/CXC/Nanjing University/X. Jin et al.

This image from NASA's Chandra X-ray Observatory shows the region around NGC 1399 and NGC 1404, two of the largest galaxies in the Fornax galaxy cluster. Located at a distance of about 60 million light years, Fornax is one of the closest galaxy clusters to Earth. This relative proximity allows astronomers to study the Fornax cluster in greater detail than most other galaxy clusters.

Chandra Serves up Cosmic Holiday Assortment

This is the season of celebrating, and the Chandra X-ray Center has prepared a platter of cosmic treats from NASA's Chandra X-ray Observatory to enjoy. This selection represents different types of objects — ranging from relatively nearby exploded stars to extremely distant and massive clusters of galaxies — that emit X-rays detected by Chandra. Each image in this collection blends Chandra data with other telescopes, creating a colorful medley of light from our Universe.

Cosmic Fountain Powered by Giant Black Hole

Image of Abell 2597
Abell 2597
Credit: X-ray: NASA/CXC/SAO/G. Tremblay et al; Radio:ALMA: ESO/NAOJ/NRAO/G.Tremblay et al, NRAO/AUI/NSF/B.Saxton; Optical: ESO/VLT

Before electrical power became available, water fountains worked by relying on gravity to channel water from a higher elevation to a lower one. This water could then be redirected to shoot out of the fountain and create a centerpiece for people to admire.

In space, awesome gaseous fountains have been discovered in the centers of galaxy clusters. One such fountain is in the cluster Abell 2597. There, vast amounts of gas fall toward a supermassive black hole, where a combination of gravitational and electromagnetic forces sprays most of the gas away from the black hole in an ongoing cycle lasting tens of millions of years.

Scientists used data from the Atacama Large Millimeter/submillimeter Array (ALMA), the Multi-Unit Spectroscopic Explorer (MUSE) on ESO's Very Large Telescope (VLT) and NASA's Chandra X-ray Observatory to find the first clear evidence for the simultaneous inward and outward flow of gas being driven by a supermassive black hole.

To Boldly Go into Colliding Galaxy Clusters

Abell 1033
Credit: X-ray: NASA/CXC/Leiden Univ./F. de Gasperin et al;
Enterprise NCC 1701
USS Enterprise NCC 1701
Credit: Smithsonian National
Air & Space Museum

Hidden in a distant galaxy cluster collision are wisps of gas resembling the starship Enterprise — an iconic spaceship from the "Star Trek" franchise.

Galaxy clusters — cosmic structures containing hundreds or even thousands of galaxies — are the largest objects in the Universe held together by gravity. Multi-million-degree gas fills the space in between the individual galaxies. The mass of the hot gas is about six times greater than that of all the galaxies combined. This superheated gas is invisible to optical telescopes, but shines brightly in X-rays, so an X-ray telescope like NASA's Chandra X-ray Observatory is required to study it.

Making Head or Tail of a Galactic Landscape

Abell 2142
Credit:X-ray: NASA/CXC/Univ. of Geneva, D. Eckert. Optical: SDSS provided by CDS through Aladin.

Astronomers have used data from NASA's Chandra X-ray Observatory to capture a dramatic image of an enormous tail of hot gas stretching for more than a million light years behind a group of galaxies that is falling into the depths of an even-larger cluster of galaxies. Discoveries like this help astronomers learn about the environment and conditions under which the Universe's biggest structures evolve.

Galaxy clusters are the largest structures in the Universe held together by gravity. While galaxy clusters can contain hundreds or even thousands of individual galaxies, the lion's share of mass in a galaxy cluster comes from hot gas, which gives off X-rays, and unseen dark matter. How did these cosmic giants get to be so big?

Perseus’s Cosmic Dance Helps Reveal the Secrets of Galaxy Cluster Astrophysics

Stephen A. Walker
Stephen A. Walker

We welcome Stephen A. Walker, first author on our latest results from the Perseus galaxy cluster, as our guest blogger. Originally from the UK, Stephen received his PhD at the University of Cambridge, continuing there as a postdoc, before becoming a NASA Postdoctoral Program Fellow at NASA’s Goddard Space Flight Center.

The story begins in October 2010, when I started my PhD at the University of Cambridge. I was exploring new X-ray observations of the outskirts of galaxy clusters taken with Suzaku. Much like in a city, the outskirts are where clusters continue to grow outwards.

Galaxy clusters are the largest gravitationally bound structures of the universe, consisting of hundreds or thousands of galaxies. The total masses of clusters are colossal, reaching up to and beyond a million billion times the mass of the sun. The vast majority of the ‘normal’ matter in these clusters (like hydrogen and helium) does not actually lie in the galaxies themselves, but rather in an extremely hot and diffuse gas between the galaxies, called the intracluster medium.

As the largest gravitationally bound structures in the universe, galaxy clusters continue to grow and accrete matter from the surrounding cosmic web of gas produced by the Big Bang. When the infalling gas falls into their deep gravitational potential wells, it is shock heated to tens of millions of degrees, and begins to emit prodigiously in the X-ray band.

A Cosmic Cold Front in the Perseus Cluster

A gigantic and resilient "cold front" hurtling through the Perseus galaxy cluster has been studied using data from NASA's Chandra X-ray Observatory. This cosmic weather system spans about two million light years and has been traveling for over 5 billion years, longer than the existence of our Solar System.

This graphic shows the cold front in the Perseus cluster. The image above contains X-ray data from Chandra — for regions close to the center of the cluster —along with data from ESA's XMM-Newton and the now-defunct German Roentgen (ROSAT) satellite for regions farther out. The Chandra data have been specially processed to brighten the contrast of edges to make subtle details more obvious.

Perseus Cluster: A New Twist in the Dark Matter Tale

Perseus Cluster
Perseus Galaxy Cluster

An innovative interpretation of X-ray data from a galaxy cluster could help scientists understand the nature of dark matter, as described in our latest press release. The finding involves a new explanation for a set of results made with NASA's Chandra X-ray Observatory, ESA's XMM-Newton and Hitomi, a Japanese-led X-ray telescope. If confirmed with future observations, this may represent a major step forward in understanding the nature of the mysterious, invisible substance that makes up about 85% of matter in the Universe.

Is Dark Matter "Fuzzy"?

Four of the 13 galaxies clusters used in the study. The clusters are, starting at the top left
and going clockwise, Abell 262, Abell 383, Abell 1413, and Abell 2390.

Astronomers have used data from NASA's Chandra X-ray Observatory to study the properties of dark matter, the mysterious, invisible substance that makes up a majority of matter in the universe. The study, which involves 13 galaxy clusters, explores the possibility that dark matter may be more "fuzzy" than "cold," perhaps even adding to the complexity surrounding this cosmic conundrum.

For several decades, astronomers have known about dark matter. Although it cannot be observed directly, dark matter does interact via gravity with normal, radiating matter (that is, anything made up of protons, neutrons, and electrons bundled into atoms). Capitalizing on this interaction, astronomers have studied the effects of dark matter using a variety of techniques, including observations of the motion of stars in galaxies, the motion of galaxies in galaxy clusters, and the distribution of X-ray emitting hot gas in galaxy clusters. Dark matter has also left an imprint on the radiation left over from the Big Bang 13.8 billion years ago.


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