Staying warm: The hot gas in clusters of galaxies

Staying warm: The hot gas in clusters of galaxies
A false-color X-ray image of the core of the Virgo cluster of galaxies. The emission comes from very hot gas between the galaxies. This gas should cool off, but doesn’t, and a new paper presents a very plausible solution to this long-time mystery. The scale mark corresponds to a physical scale of 50 light-years. Credit: NASA/Chandra X-ray Observatory

Most galaxies lie in clusters, groupings of a few to many thousands of galaxies. Our Milky Way galaxy itself is a member of the "Local Group," a band of about fifty galaxies whose other large member is the Andromeda Galaxy about 2.3 million light-years away. The closest large cluster of galaxies to us is the Virgo Cluster, about 50 million light-years away, with about 2000 members.

The space between the in clusters is filled with very hot gas – its temperature is of order ten million kelvin, or even higher. Most of the matter in the so-called intracluster medium is in the form of this very hot gas. Hot gas should cool off, and one of the major puzzles about is that the hot intracluster gas does not seem to cool. In fact, calculations based on the energy radiated indicate that the gas should cool about ten times faster than is observed. X-ray observations of the hot gas also suggest that it might be turbulent, perhaps driven by mechanical flows of matter pouring outward from the at the centers of the clusters' galaxies, perhaps creating inflating bubbles of fast-moving charged particles that stir and heat the gas. Unfortunately, current X-ray observatories do not have the ability to measure the supposed gas velocities to test this proposed solution.

A team of astronomers including CfA scientists Bill Forman and Alexey Vikhlinin have pioneered a new method to evaluate the turbulence of the hot intracluster gas. They took advantage of the superb spatial resolution and sensitive images from the Chandra X-Ray Observatory to probe small clumps distributed through two clusters, Perseus and Virgo. They analyze the structures as resulting from turbulence, and then inferred the turbulent velocities needed, deriving values up to about 145 kilometers per second. These velocities are indeed adequate to heat the gas over all the scales observed over the , and could readily be produced by black hole jets. The results are very encouraging, though not definitive, and imply that no mysterious mechanisms needed to be invoked to explain the enduring hot gas.


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More information: "Turbulent Heating in Galaxy Clusters Brightest in X-rays," I. Zhuravleva, E. Churazov, A. A. Schekochihin, S. W. Allen, P. Arévalo, A. C. Fabian, W. R. Forman, J. S. Sanders, A. Simionescu, R. Sunyaev, A. Vikhlinin, & N. Werner, Nature, 515, 85, 2014.
Journal information: Nature

Citation: Staying warm: The hot gas in clusters of galaxies (2014, November 28) retrieved 19 July 2019 from https://phys.org/news/2014-11-hot-gas-clusters-galaxies.html
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Nov 28, 2014
The results are very encouraging, though not definitive, and imply that no mysterious mechanisms needed to be invoked to explain the enduring hot gas.


Well, except for fictional black holes. One these days astrophysicists will better understand plasma processes, but if history is any gauge it will take many decades.

Nov 28, 2014
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Nov 28, 2014
The problem is that this mechanism implies a lot of ejected gas, originating from where? This question is conveniently omitted from the story, since the answer is so awkward for Huge Bang Fanciers. It originates mostly from within the active core star.

yyz
Nov 28, 2014
"The problem is that this mechanism implies a lot of ejected gas, originating from where?"

Sorry, I don't understand why the gas must be ejected from the galaxies at all. Most of the (visible) mass in galaxy clusters is tied up with the hot intercluster medium(ICM) between galaxies. This gas is thought to be left over material from the formation of the cluster galaxies. Both AGN and the motions of individual galaxies in the cluster are thought to contribute to turbulence in the ICM.

So again, tell me why the ICM _must_ be ejected from cluster galaxies?

Nov 28, 2014
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Nov 28, 2014
This comment has been removed by a moderator.

Nov 30, 2014
Well, except for fictional black holes. One these days astrophysicists will better understand plasma processes, but if history is any gauge it will take many decades.
@cd
you've made this claim over and over and you have yet to be able to provide any proof that astrophysicists do not know anything about (or are not taught) plasma physics

you've also been directly refuted with the following study: http://arxiv.org/...92v1.pdf
you specifically said you ignored this study because of the title/first line... but if you read it, it completely DEBUNKS your conjecture about astrophysicists not knowing plasma physics
then there is the following debunking your claims
http://www.pppl.gov
http://ocw.mit.edu/index.htm

you like to repeat your lies as though repetition would somehow validate them
you are wrong

eu is debunked pseudoscience

Dec 01, 2014
"The scale mark corresponds to a physical scale of 50 light-years"

uhm, 15kpc = 50 000 Ly

Dec 01, 2014
@cd
you've made this claim over and over and you have yet to be able to provide any proof that astrophysicists do not know anything about (or are not taught) plasma physics


While at the same time the examples of them being "surprised", "perplexed", or finding "unexpected" phenomena keep flooding in like the CO2 polluting your brain. Here is another example of a fundamental property of plasma we have been aware of for 70+ years being a "surprise" to astros when they come across it. They prefer to relate it to a fictional Star Trek nonsense to describe what is generally known to be ubiquitous in all plasmas.

http://phys.org/n...nds.html


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