Showing posts with label Abell 2256. Show all posts
Showing posts with label Abell 2256. Show all posts

Wednesday, February 01, 2023

Abell 2256: Untangling a Knot of Galaxy Clusters

Abell 2256 (Labeled)
Credit: X-ray: Chandra: NASA/CXC/Univ. of Bolonga/K. Rajpurohit et al.; XMM-Newton: ESA/XMM-Newton/Univ. of Bolonga/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.

Astronomers studying this object are trying to tease out what has led to this unusual-looking structure. Each telescope tells a different part of the story. Galaxy clusters are some of the biggest objects in the universe containing hundreds or even thousands of individual galaxies. In addition, they contain enormous reservoirs of superheated gas, with temperatures of several million degrees Fahrenheit. Only X-ray telescopes like Chandra and XMM can see this hot gas. A labeled version of the figure shows gas from two of the galaxy clusters, with the third blended too closely to separate from the others.

Halo of Radio Emission
Credit: LOFAR/ASTRON)

Paper III by Rajpurohit and collaborators will study the galaxies producing radio waves in Abell 2256. This cluster contains an unusually large number of such galaxies, possibly because the collision and merger are triggering the growth of supermassive black holes and consequent eruptions. More details about the LOFAR image of Abell 2256 will be reported in an upcoming paper by Erik Osinga.

The full list of co-authors for papers I and II include researchers from the University of Bologna, Italy (Franco Vazza, Annalisa Bonafede, Andrea Botteon, Christopher J. Riseley, Paola Domínguez-Fernández, Chiara Stuardi, and Daniele Dallacasa); Leiden Observatory, Leiden University, the Netherlands (Erik Osinga, Reinout J. van Weeren, Timothy Shimwell, Huub Röttgering, and George Miley); Thüringer Landessternwarte, Tautenburg, Germany (Matthias Hoeft and Alexander Drabent); INAF-Istituto di Radio Astronomia, Bologna, Italy (Gianfranco Brunetti and Rossella Cassano); Hamburger Sternwarte, Germany (Denis Wittor, Marcus Brüggen, and Francesco de Gasperin); Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Italy (Marisa Brienza); Center for Astrophysics, Harvard | Smithsonian (William Forman); Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley (Sangeeta Rajpurohit); Physical Research Laboratory, Ahmedabad, India (Arvind Singh Rajpurohit); Universität Würzburg, Würzburg, Germany (Etienne Bonnassieux), and INAF–IASF Milano, Italy (Mariachiara Rossetti).

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.





Visual Description:

This release features a composite image of at least three galaxy clusters colliding in a jumbled scene. The resulting giant galaxy cluster, known as Abell 2256, resembles a grainy, pixilated, sky blue cloud topped with licks of flaming red hair. The cloud is adorned with red shapes and streaks, and set against a black background heavily dotted with colorful specks. The image combines X-ray, radio, optical, and infrared data. In this release, the composite image is presented both with, and without, labels.

Near our lower left sits the oval-shaped, sky-blue cloud pixelated with white dots. This is the center of the combined galaxy cluster. The blue cloud shows enormous reservoirs of superheated gas, with temperatures of several million degrees Fahrenheit.

Shooting out of the giant cluster, angled toward our upper-middle right, is a straight, thin red line labeled C. This is a jet; a stream of particles blasting away from a giant black hole. A second, much shorter jet, labeled I, crosses the tip of the first jet near the right hand side of the image.

In the giant cluster, on the righthand side, are several irregular shapes. One, labeled A, resembles a bright white bean with a red outline. Beside it, labeled B, is a tangle of overlapping red shapes dangling out the bottom of the cloud. These are filaments, the result of jets interacting with gas. Three other irregular red filaments can be found to our left, just outside of the giant cluster.

At the upper right hand edge of the oval-shaped giant cluster are sweeping sheets of red, which resemble lapping flames or licks of red hair. These relics are the results of shockwaves, likely generated by the collision of gas from the different clusters.




Fast Facts for (Abell 2256):

Scale: Image is about 22.5 arcmin (5.6 million light-years) across.
Category:
Groups & Clusters of Galaxies
Coordinates (J2000): RA 17h 03m 43.5s | Dec +78° 43´ 03"
Constellation: Ursa Minor
Observation Dates: 4 observations from Aug 14 to Sep 26, 2014
Observation Time: 49 hours 55 minutes (2 days 1 hours)
Obs. ID: 17129, 16514, 16515, 17516
Instrument:
ACIS
References: Rajpurohit, K., et al., 2022, ApJ, 927, 80; arXiv:2111.04449 (Paper I); Rajpurohit, K., et al., 2022, Accepted, A&A; arXiv:2209.03288 (Paper II)
Color Code: X-ray: blue; Radio: red, white; Optical: red, green, blue.
Distance Estimate: About 780 million light-years


Tuesday, May 03, 2022

Featured Image: Deep Imaging of a Radio Relic


 

New radio observations from uGMRT (red) highlight the detailed structure of the radio relic that curves around the diffuse X-ray emission seen by the Chandra X-ray Observatory (blue). Various regions of the radio relic are labeled. Click for high-resolution version. Credit: Rajpurohit et al. 2022

Galaxy cluster Abell 2256 is home to an incredible variety of structures traced by radio emission. The most prominent structure is an extended radio relic: a region of diffuse radio emission found on the outskirts of a cluster of galaxies. The precise cause of these massive radio relics is unknown, though shocks are expected to play a central role; the acceleration, re-acceleration, or compression of plasma by a shock wave could all cause the observed emission. Using new deep observations by the Giant Metrewave Radio Telescope (uGMRT) — shown above and to the right — a team led by Kamlesh Rajpurohit (University of Bologna, Italy; National Institute of Astrophysics, Italy; Thuringian State Observatory, Germany) investigated the cause of the striking radio emission surrounding Abell 2256. The new high-resolution images and spectra suggest that the surface of the radio relic traces a shock front, which is jumbled and twisted by interactions with the hot, turbulent plasma that suffuses the space between the galaxies in the cluster. For more fantastic images of the Abell 2256 radio relic, be sure to read the full article below!

Citation

“Deep Low-frequency Radio Observations of A2256. I. The Filamentary Radio Relic,” K. Rajpurohit et al 2022 ApJ 927 80. doi:10.3847/1538-4357/ac4708

By Kerry Hensley

Source:  American Astronomical Society - AAS Nova


Thursday, March 12, 2015

Mysterious Phenomena in a Gigantic Galaxy-Cluster Collision

Abell 2256, in a "true color" radio image made with the VLA
Credit: Owen et al., NRAO/AUI/NSF


Researchers using the Karl G. Jansky Very Large Array (VLA) have produced the most detailed image yet of a fascinating region where clusters of hundreds of galaxies are colliding, creating a rich variety of mysterious phenomena visible only to radio telescopes.

The scientists took advantage of new VLA capabilities to make a "true color" radio image. This image shows the region as it would appear if human eyes were sensitive to radio waves instead of light waves. In this image, red shows where longer radio waves predominate, and blue shows where shorter radio waves predominate, following the pattern we see in visible light.

The image shows a number of strange features the astronomers think are related to an ongoing collision of galaxy clusters. The region is called Abell 2256, and is about 800 million light-years from Earth and some 4 million light-years across. The image covers an area in the sky almost as large as the full moon. Studied by astronomers for more than half a century with telescopes ranging from radio to X-ray, Abell 2256 contains a fascinating variety of objects, many of whose exact origins remain unclear.

With monikers such as "Large Relic," "Halo," and "Long Tail," the features in this region are seen in greater fidelity than ever before, said Frazer Owen, of the National Radio Astronomy Observatory (NRAO). "The image reveals details of the interactions between the two merging clusters and suggests that previously unexpected physical processes are at work in such encounters," he said.

Owen worked with Lawrence Rudnick of the University of Minnesota; Jean Eilek of New Mexico Tech; and Urvashi Rau, Sanjay Bhatnagar, and Leonid Kogan of NRAO. The researchers presented their results in the Astrophysical Journal.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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Contact: 

Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu




Wednesday, May 23, 2012

Colliding galaxy cluster unravelled

Galaxy cluster Abell 2256 at 60 MHz made with LOFAR
An international team of astronomers has used the International LOFAR Telescope from ASTRON, the Netherlands Institute for Radio Astronomy, to study the formation of the galaxy cluster Abell 2256. Abell 2256 is a cluster containing hundreds of galaxies at a distance of 800 million lightyears. ‘The structure we see in the radio images made with LOFAR provides us with information about the origin of this cluster, explains lead author dr. Reinout van Weeren (Leiden University and ASTRON). The study will be published in the scientific journal Astronomy & Astrophysics. The research involved a large team of scientists from 26 different universities and research institutes.

LOFAR has made the first images of Abell 2256 in the frequency range of 20 to 60 MHz. What came as a surprise to scientists was that the cluster of galaxies was brighter and more complex than expected. Dr. van Weeren: ‘We think that galaxy clusters form by mergers and collisions of smaller clusters'. Abell 2256 is a prime example of a cluster that is currently undergoing a collision. The radio emission is produced by tiny elementary particles that move nearly at the speed of light. With LOFAR it is possible to study how these particles get accelerated to such speeds. ‘In particular, we will learn how this acceleration takes place in regions measuring more than 10 million light years across', says Dr. Gianfranco Brunetti from IRA-INAF in Bologna, Italy, who together with Prof. Marcus Brüggen from the Jacobs University in Bremen, coordinates the LOFAR work on galaxy clusters.

LOFAR was built by a large international consortium led by the Netherlands and which includes Germany, France, the United Kingdom and Sweden. One of the main goals of LOFAR is to survey the entire northern sky at low radio frequencies, with a sensitivity and resolution about 100 times better than what has been previously done. Scientists believe that this survey will discover more than 100 million objects in the distant Universe. ‘Soon we will start our systematic surveys of the sky that will lead to great discoveries', says Prof. Huub Röttgering from Leiden University and Principal Investigator of the "LOFAR Survey Key Project".


For more information, contact:

Dr. Reinout van Weeren, astronomer,
Leiden University and ASTRON
Tel.: +31 71 527 5864
E-mail: rvweeren@strw.leidenuniv.nl
Prof. Huub Röttgering, astronomer,
Leiden University
Tel.: +31 6 41522603
E-mail: rottgering@strw.leidenuniv.nl

Femke Boekhorst,
PR & Communication, ASTRON
Tel.: +31 521 595 204
E-mail: boekhorst@astron.nl

Link to the paper:
http://home.strw.leidenuniv.nl/~rvweeren/A2256_LBA_arx.pdf