Clues to the growth of the colossus in Coma

Sep 19, 2013
Enormous arms of hot gas have been revealed in the Coma galaxy cluster in data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton. A specially processed Chandra image (pink) has been combined with optical data from the Sloan Digital Sky Survey (white and blue) to highlight these spectacular arms. Researchers think that these arms -- which span at least a half million light years -- were most likely formed when smaller galaxy clusters had their gas stripped away by the head wind created by the motion of clusters through the hot gas. Credit: X-ray: NASA/CXC/MPE/J. Sanders et al; Optical: SDSS

A team of astronomers has discovered enormous arms of hot gas in the Coma cluster of galaxies by using NASA's Chandra X-ray Observatory and ESA's XMM-Newton. These features, which span at least half a million light years, provide insight into how the Coma cluster has grown through mergers of smaller groups and clusters of galaxies to become one of the largest structures in the Universe held together by gravity.

A new composite image, with Chandra data in pink and optical data from the Sloan Digital Sky Survey appearing in white and blue, features these spectacular arms. In this image, the Chandra data have been processed so extra detail can be seen.

The X-ray emission is from multimillion-degree gas and the optical data shows galaxies in the Coma Cluster, which contain only about one-sixth the mass in hot gas. Only the brightest X-ray emission is shown here, to emphasize the arms, but the hot gas is present over the entire field of view.

Researchers think that these arms were most likely formed when smaller galaxy clusters had their gas stripped away by the head wind created by the motion of the cluster through the hot gas, in much the same way that the headwind created by a roller coaster blows the hats off riders.

Coma is an unusual because it contains not one, but two giant elliptical galaxies near its center. These two giant elliptical galaxies are probably the vestiges from each of the two largest clusters that merged with Coma in the past. The researchers also uncovered other signs of past collisions and mergers in the data.

From their length, and the speed of sound in the hot gas (about 4 million km/hr), the newly discovered X-ray arms are estimated to be about 300 million years old, and they appear to have a rather smooth shape. This gives researchers some clues about the conditions of the hot gas in Coma. Most expect that mergers between clusters like those in Coma will produce strong turbulence, like ocean water that has been churned by many passing ships. Instead, the smooth shape of these lengthy arms points to a rather calm setting for the hot gas in the Coma cluster, even after many mergers.

X-ray emission from the center of the Coma cluster of galaxies, showing the multi-million degree hot gas in the cluster. This image measures 2.2 million light years across. Credit: J.S. Sanders et al.

Large-scale magnetic fields are likely responsible for the small amount of turbulence that is present in Coma. Estimating the amount of turbulence in a galaxy cluster has been a challenging problem for astrophysicists. Researchers have found a range of answers, some of them conflicting, and so observations of other clusters are needed.

Two of the arms appear to be connected to a group of galaxies located about two million light years from the center of Coma. One or both of these arms connects to a larger structure seen in the XMM-Newton data, and spans a distance or at least 1.5 million . A very thin tail also appears behind one of the galaxies in Coma. This is probably evidence of gas being stripped from a single galaxy, in addition to the groups or clusters that have merged there.

These new results on the Coma cluster, which incorporate over six days worth of Chandra observing time, will appear in the September 20, 2013, issue of the journal Science. The first author of the paper is Jeremy Sanders from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. The co-authors are Andy Fabian from Cambridge University in the UK; Eugene Churazov from the Max Planck Institute for Astrophysics in Garching, Germany; Alexander Schekochihin from University of Oxford in the UK; Aurora Simionescu from Stanford University in Stanford, CA; Stephen Walker from Cambridge University in the UK and Norbert Werner from Stanford University in Stanford, CA.

Explore further: Astronomers release most detailed catalogue ever made of the visible Milky Way

More information: "Linear Structures in the Core of the Coma Cluster of Galaxies," by J.S. Sanders et al. Science, 2013. www.sciencemag.org/content/341/6152/1365

Related Stories

Dwarf galaxy caught ramming into a large spiral

Aug 14, 2013

Observations with NASA's Chandra X-ray Observatory have revealed a massive cloud of multimillion-degree gas in a galaxy about 60 million light years from Earth. The hot gas cloud is likely caused by a collision ...

Messier 61 looks straight into Hubble's camera

Jun 21, 2013

(Phys.org) —The NASA/ESA Hubble Space Telescope has captured this image of nearby spiral galaxy Messier 61, also known as NGC 4303. The galaxy, located only 55 million light-years away from Earth, is roughly ...

A galaxy cluster gets sloshed

Dec 14, 2011

(PhysOrg.com) -- Like wine in a glass, vast clouds of hot gas are sloshing back and forth in Abell 2052, a galaxy cluster located about 480 million light years from Earth. X-ray data (blue) from NASA's Chandra ...

Hubble catches a spiral in the air pump

Sep 06, 2013

(Phys.org) —Lying more than 110 million light-years away from Earth in the constellation of Antlia (The Air Pump) is the spiral galaxy IC 2560, shown here in an image from NASA/ESA Hubble Space Telescope. ...

Recommended for you

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Modified theory of dark matter

Sep 12, 2014

Dark matter is an aspect of the universe we still don't fully understand. We have lots of evidence pointing to its existence (as I outlined in a series of posts a while back), and the best evidence we have point ...

Gaia discovers its first supernova

Sep 12, 2014

(Phys.org) —While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy far, far away.

User comments : 11

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (12) Sep 19, 2013
There's those Birkeland currents...
yyz
5 / 5 (9) Sep 19, 2013
First it was hydrogen-alpha filaments around a dozen members of the Coma Cluster that were supposedly "consistent" with BCs (no refs given). Now it's (unrelated) million-degree X-ray emitting gas in the intercluster medium of the Coma Cluster that's supposedly evidence of BCs. The presence of this hot ICM has been known since the 1970s, now seen in unprecedented resolution with Chandra.

Got a link to ANY published work that describes BCs in the Coma Cluster, instead of just making baseless and unsupported claims?

I didn't think so.
yyz
5 / 5 (9) Sep 19, 2013
All I'm asking for is some reliable, published evidence of BCs in the Coma Cluster cantdrive. This should be really simple. Along with the Virgo Galaxy Cluster, the Coma Cluster is probably the best studied galaxy cluster known to science. There are over a thousand papers published on this cluster, yet not a single paper mentions BCs in the Coma Cluster: http://ned.ipac.c...of=table

If you want to appear credible on this subject, YOU need to provide some (published, peer-reviewed) evidence for what you are claiming. Not some junk science on a website.
Urgelt
not rated yet Sep 20, 2013
I'd like to pose an honest question.

We have this humongous blob of hot, x-ray emitting gas in the Coma Cluster. A really interesting feature it is, too. Scientists are saying sound can travel in it, and that's an eye opener for me, I don't know about anyone else.

Why would we *not* expect currents in that thing? What precludes them? Scientists see evidence of big magnetic fields. Why not electromagnetic currents?

I hasten to add, I'm not advocating for any fringe theories here, I'm just asking if it's possible, given what is known about that object.
Urgelt
4.2 / 5 (6) Sep 20, 2013
Spoken like a true crank, Franklins.

Every answer in science gives rise to more questions... except in crank land, where uncertainty is never tolerated.
no fate
5 / 5 (5) Sep 20, 2013
I'd like to pose an honest question.

We have this humongous blob of hot, x-ray emitting gas in the Coma Cluster. A really interesting feature it is, too. Scientists are saying sound can travel in it, and that's an eye opener for me, I don't know about anyone else.

Why would we *not* expect currents in that thing? What precludes them? Scientists see evidence of big magnetic fields. Why not electromagnetic currents?

I hasten to add, I'm not advocating for any fringe theories here, I'm just asking if it's possible, given what is known about that object.


Particle flow through magnetic flux is a current, no question. It's that he thinks those particles generate that field when in reality they are reacting to it. More detailed observation may one day reveal directionality of the particle movements, but Cantdrive fails repeatedly to fathom the correlation between particle density required to generate a field vs. particles reacting to one.
cantdrive85
1 / 5 (9) Sep 20, 2013
No, I just don't presume magic or god in space. Something must create the magnetic fields or the "flux" you insist is already there.
Fleetfoot
5 / 5 (5) Sep 20, 2013
Why would we *not* expect currents in that thing? What precludes them?


You need to think about the question a bit more. It is reasonable to think of the hot, ionised gas as a conductor, albeit with some high value of bulk resistivity due to the low density. In localised areas where there are stellar magnetic fields, you might expect induced eddy currents, that's not unreasonable.

However, if you imagine a current flowing radially from the core to the extremities of the cloud, you hit a problem, currents need somewhere to go. Without completing the loop, charge builds up creating a potential which stops the flow. If the blob is isolated, the equivalent circuit is a capacitor, so you can't get DC current flow.

If you postulate a flow through the WHIM then other clusters must be at a different potential, as if there were batteries connected between them, but then you hit the big problem with the crank EU philosophy: "batteries not included".
Captain Stumpy
2 / 5 (8) Sep 22, 2013
Only in parasitic science oriented to prolongation of research at any price.


as opposed to your "parasitic" pseudoscience which serves only to annoy or vex?

at least science has reproducible experiments that prove theories, rather than just shouting from behind computer screens, using anonymity as a defense against ignorance and false claims (or false science, as the Aether was disproved a century ago), like you do...
GSwift7
5 / 5 (1) Sep 23, 2013
Scientists are saying sound can travel in it, and that's an eye opener for me, I don't know about anyone else


When they say "the speed of sound" in this context, they aren't really talking about a 'sound' that you could hear. They are talking about the speed of compressional shock waves. If you were in a space ship there, you wouldn't hear any sound coming through the hull of your spaceship. It's more like a moving pulse in the density of the cloud, and the wavelength would be so long that the transition would be very gradual to a local observer. Think really big distance and time scales here, like the shockwave of a supernova moving out several lightyears into the cloud. It's more a result of absorption and re-emission of photons, and EM forces rather than physical contact between molecules.
cantdrive85
1 / 5 (5) Oct 01, 2013
More on the EU POV of these gassy arms;
http://www.youtub...LwfVRZdA