Groups & Clusters of Galaxies

NASA's Chandra Identifies an Underachieving Black Hole

Image of Quasar H1821+643
Quasar H1821+643
Credit: X-ray: NASA/CXC/Univ. of Nottingham/H. Russell et al.; Radio: NSF/NRAO/VLA; Image Processing: NASA/CXC/SAO/N. Wolk

This image shows a quasar, a rapidly growing supermassive black hole, which is not achieving what astronomers would expect from it, as reported in our latest press release. Data from NASA’s Chandra X-ray Observatory (blue) and radio data from the NSF’s Karl G. Jansky’s Very Large Array (red) reveal some of the evidence for this quasar’s disappointing impact on its host galaxy.

Known as H1821+643, this quasar is about 3.4 billion light-years from Earth. Quasars are a rare and extreme class of supermassive black holes that are furiously pulling material inwards, producing intense radiation and sometimes powerful jets. H1821+643 is the closest quasar to Earth in a cluster of galaxies.

Quasars are different than other supermassive black holes in the centers of galaxy clusters in that they are pulling in more material at a higher rate. Astronomers have found that non-quasar black holes growing at moderate rates influence their surroundings by preventing the intergalactic hot gas from cooling down too much. This regulates the growth of stars around the black hole.

Chandra Ties Powerful Black Hole to Stellar Beads-on-a-String

Osase Omoruyi with her parents favorite beads.
Osase Omoruyi with her parents’ favorite beads.

We are happy to welcome Osase Omoruyi as a guest blogger. Osase is the first author of the paper that is the focus of our latest press release, and is an NSF Graduate Research Fellow at Harvard University, where she is currently completing her PhD in Astronomy and Master’s in History of Science. Osase uses a variety of telescopes, from X-ray through Radio, as well as computer simulations, to study the fascinating life of galaxies. She is particularly interested in how stars and black holes, which are small in comparison to the scale of a whole galaxy, can transform how galaxies change over time.

In 2008, astronomers using the Wisconsin–Indiana–Yale NOAO (WIYN) telescope in Arizona published images of the newly discovered galaxy cluster named SDSS J1531+3414 (SDSS J1531 for short). At first glance, it seemed like a standard massive cluster of galaxies with one giant galaxy in its center, hundreds of others surrounding it, and arc-like structures caused by gravitational lensing – a phenomenon where the cluster's gravity bends light from galaxies behind it.

However, our understanding of SDSS J1531 changed dramatically in 2014 when the Hubble Space Telescope provided a higher-resolution view of the cluster from space. Contrary to initial beliefs, the heart of the cluster housed not one but two massive galaxies, on course to collide and merge into a single entity. They also featured 19 clusters of young stars wrapped around them in a pattern that resembled beads on a string.

Stellar Beads on a String

Image of SDSS J1531+3414
SDSS J1531+3414
Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.;
Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk

Astronomers have discovered one of the most powerful eruptions from a black hole ever recorded in the system known as SDSS J1531+3414 (SDSS J1531 for short). As explained in our press release, this mega-explosion billions of years ago may help explain the formation of a striking pattern of star clusters around two massive galaxies, resembling “beads on a string.”

SDSS J1531 is a massive galaxy cluster containing hundreds of individual galaxies and huge reservoirs of hot gas and dark matter. At the center of SDSS J1531, which is located about 3.8 billion light-years away, two of the cluster’s largest galaxies are colliding with each other.

Astronomers used several telescopes to study SDSS J1531 including NASA’s Chandra X-ray Observatory, and the Low Frequency Array (LOFAR), a radio telescope. This composite image shows SDSS J1531 in X-rays from Chandra (blue and purple) that have been combined with radio data from LOFAR (dark pink) as well as an optical image from the Hubble Space Telescope (appearing as yellow and white). The inset gives a close-in view of the center of SDSS J1531 in optical light, showing the two large galaxies and a set of 19 large clusters of stars, called superclusters, stretching across the middle. The image shows these star clusters are arranged in an ‘S’ formation that resembles beads on a string.

Astronomers Find Spark of Star Birth Across Billions of Years

Image of four different galaxy clusters observed for the survey
Brightest Cluster Galaxies Survey
Credit: X-ray: NASA/CXC/MIT/M. Calzadilla el al.; Optical: NASA/ESA/STScI;
Image Processing: NASA/CXC/SAO/N. Wolk & J. Major

These four images represent a sample of galaxy clusters that are part of the largest and most complete study to learn what triggers stars to form in the universe’s biggest galaxies, as described in our latest press release. This research, made using NASA’s Chandra X-ray Observatory and other telescopes, showed that the conditions for stellar conception in these exceptionally massive galaxies have not changed over the last ten billion years.

Galaxy clusters are the largest objects in the universe held together by gravity and contain huge amounts of hot gas seen in X-rays. This hot gas weighs several times the total mass of all the stars in all the hundreds of galaxies typically found in galaxy clusters. In the four galaxy cluster images in this graphic, X-rays from hot gas detected by Chandra are in purple and optical data from NASA’s Hubble Space Telescope, mostly showing galaxies in the clusters, are yellow and cyan.

NASA Telescopes Discover Record-Breaking Black Hole

Image of UHZ1
Credit: X-ray: NASA/CXC/SAO/Ákos Bogdán; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare & K. Arcand

This image contains the most distant black hole ever detected in X-rays, a result that may explain how some of the first supermassive black holes in the universe formed. As we report in our press release, this discovery was made using X-rays from NASA’s Chandra X-ray Observatory (purple) and infrared data from NASA’s James Webb Space Telescope (red, green, blue).

The extremely distant black hole is located in the galaxy UHZ1 in the direction of the galaxy cluster Abell 2744. The galaxy cluster is about 3.5 billion light-years from Earth. Webb data, however, reveal that UHZ1 is much farther away than Abell 2744. At some 13.2 billion light-years away, UHZ1 is seen when the universe was only 3% of its current age.

"El Gordo": A Galaxy Cluster That Pushes the Limits

Image of El Gordo
El Gordo
Credit: X-ray: NASA/CXC/Rutgers/J. Hughes et al.; Infrared: NASA/ESA/CSA, J.M. Diego (IFCA), B.Frye (Univ. of Arizona), P.Kamieneski, T.Carleton & R.Windhorst (ASU);

When astronomers discovered the galaxy cluster ACT-CL J0102-4915 in 2012 with NASA's Chandra X-ray Observatory and ground-based optical telescopes, they nicknamed it "El Gordo" (Spanish for the "Fat One") because of its gigantic mass. Scientists estimate that El Gordo contains as much as 3 million billion (3,000,000,000,000,000) times the mass of the Sun. Thanks to its heft, El Gordo acts as a natural lens, distorting the light from more distant objects behind it through a process known as gravitational lensing.

A new composite image of El Gordo shows the diffuse, superheated gas in the cluster observed in X-rays from Chandra (blue) that have been combined with a new infrared image from NASA's James Webb Space Telescope (red, green, and blue). Webb's image shows galaxies in El Gordo plus background galaxies located further away from Earth. El Gordo is located about 7.3 billion light-years from Earth and the background galaxies are at a range of different distances including several that are 12.3 billion light-years from Earth. The appearance of some of the background galaxies has been distorted into a variety of unusual and highly elongated shapes because of gravitational lensing by the cluster.

Unexpectedly Calm and Remote Galaxy Cluster Discovered

SPT-CL J2215-3537
Credit: X-ray: NASA/CXC/MIT/M. Calzadilla; UV/Optical/Near-IR/IR: NASA/STScI/HST; Image processing: N. Wolk

The discovery of the most distant galaxy cluster with a specific important trait – as described in our press release – is providing insight into how these gigantic structures formed and why the universe looks like it does in the present day.

Galaxies Go on a Deep Dive and Leave Fiery Tail Behind

Image of NGC 4839
NGC 4839
Credit: X-ray: Chandra: NASA/SAO/Univ. of Alabama/M. S. Mirakhor et al.; XMM: ESA/XMM-Newton;
Optical: SDSS; Image processing: N. Wolk

A group of galaxies is plunging into the Coma galaxy cluster and leaving behind an enormous tail of superheated gas. Astronomers have confirmed this is the longest known tail behind a galaxy group and used it to gain a deeper understanding of how galaxy clusters – some of the largest structures in the universe – grow to their enormous sizes.

Powerful Yet Lonely: The Distant Quasar Left Alone in its Group

An image of Valentina Missaglia on the walkway in front of a ground-based observatory on a sunny day.
Valentina Missaglia

We are happy to welcome Valentina Missaglia as a guest blogger. She is the first author of the paper that is the subject of our latest press release. She is currently a postdoctoral researcher at the Institute of Astrophysics — FORTH in Heraklion (Crete) in the SMILE (“Search for Milli-LEnses”) group, recently funded by an ERC grant, that aims at investigating the nature of dark matter through observations of gravitational lenses on milli-arcsecond scales. Valentina earned her Ph.D. from the University of Turin (Italy) and her research focuses on radio and X-ray emission from radio-loud active galactic nuclei (which contain supermassive black holes that are rapidly pulling in material, producing intense radio waves) and how these sources interact with the surrounding medium. Before starting her Ph.D. in 2019, Valentina was a visiting student at the Center of Astrophysics | Harvard & Smithsonian, where she collaborated with Dr. Ralph Kraft on observations of galaxy clusters performed with NASA’s Chandra X-ray Observatory.

Looking at the night sky with the naked eye, we can only see an infinitesimal part of what the Universe contains, and the largest part cannot even be “seen”. Radio wavelengths have gifted us some of the most fascinating astronomical sources: radio-loud active galactic nuclei in the centers of galaxies, which can produce jets that extend way farther out from the optical galaxy itself.

The most powerful radio sources in the northern hemisphere are listed in a well- studied catalog, the Third Cambridge Catalog (3C), which contains the source we investigated with multiwavelength observations: 3C 297. This source appeared very intriguing in observations performed with Chandra in 2016. Therefore, we requested more time to better investigate features that we uncovered thanks to this first short observation, such as hot, X-ray emitting gas around our source.

Untangling a Knot of Galaxy Clusters

Multiwavelength image of Abell 2256
Abell 2256
Credit: X-ray: Chandra: NASA/CXC/Univ. of Bologna/K. Rajpurohit et al.; XMM-Newton: ESA/XMM-Newton/Univ. of Bologna/K. Rajpurohit et al. Radio: LOFAR: LOFAR/ASTRON; GMRT: NCRA/TIFR/GMRT; VLA: NSF/NRAO/VLA; Optical/IR: Pan-STARRS

Astronomers have captured a spectacular, ongoing collision between at least three galaxy clusters. Data from NASA’s Chandra X-ray Observatory, ESA’s (European Space Agency’s) XMM-Newton, and a trio of radio telescopes is helping astronomers sort out what is happening in this jumbled scene. Collisions and mergers like this are the main way that galaxy clusters can grow into the gigantic cosmic edifices seen today. These also act as the largest particle accelerators in the universe.

The giant galaxy cluster forming from this collision is Abell 2256, located 780 million light-years from Earth. This composite image of Abell 2256 combines X-rays from Chandra and XMM in blue with radio data collected by the Giant Metrewave Radio Telescope (GMRT), the Low Frequency Array (LOFAR), and the Karl G. Jansky Very Large Array (VLA) all in red, plus optical and infrared data from Pan-STARRs in white and pale yellow.


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