CXC: X-ray Discovery Points to Location of Missing Matter

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CXC: X-ray Discovery Points to Location of Missing Matter

Post by bystander » Tue May 11, 2010 8:30 pm

X-ray Discovery Points to Location of Missing Matter
Chandra X-ray Center - 11 May 2010
Using observations with NASA's Chandra X-ray Observatory and ESA's XMM-Newton, astronomers have announced a robust detection of a vast reservoir of intergalactic gas about 400 million light years from Earth. This discovery is the strongest evidence yet that the "missing matter" in the nearby Universe is located in an enormous web of hot, diffuse gas.

This missing matter — which is different from dark matter -- is composed of baryons, the particles, such as protons and electrons, that are found on the Earth, in stars, gas, galaxies, and so on. A variety of measurements of distant gas clouds and galaxies have provided a good estimate of the amount of this "normal matter" present when the universe was only a few billion years old. However, an inventory of the much older, nearby universe has turned up only about half as much normal matter, an embarrassingly large shortfall.

The mystery then is where does this missing matter reside in the nearby Universe? This latest work supports predictions that it is mostly found in a web of hot, diffuse gas known as the Warm-Hot Intergalactic Medium (WHIM). Scientists think the WHIM is material left over after the formation of galaxies, which was later enriched by elements blown out of galaxies.
Image
H2356-309: X-ray Discovery Points to Location of Missing Matter
Scientists have used NASA's Chandra X-ray Observatory and ESA's XMM-Newton to detect a vast reservoir of gas lying along a wall-shaped structure of galaxies about 400 million light years from Earth. In this artist's impression, a close-up view of the so-called Sculptor Wall is depicted. Spiral and elliptical galaxies are shown in the wall along with the newly detected intergalactic gas, part of the so-called Warm Hot Intergalactic Medium (WHIM), shown in blue. This discovery is the strongest evidence yet that the "missing matter" in the nearby Universe is located in an enormous web of hot, diffuse gas.

The X-ray emission from WHIM in this wall is too faint to be detected, so instead a search was made for absorption of light from a bright background source by the WHIM, using deep observations with Chandra and XMM. This background source is a rapidly growing supermassive black hole located far beyond the wall at a distance of about two billion light years. This is shown in the illustration as a star-like source, with light traveling through the Sculptor Wall towards the Earth. The relative location of the background source, the Sculptor Wall, and the Milky Way galaxy are shown in a separate plot, where the view instead looks down on the source and the Wall from above.

An X-ray spectrum of the background source is given in the inset, where the yellow points show the Chandra data and the red line shows the best model for the spectrum after including all of the Chandra and XMM data. The dip in X-rays towards the right side of the spectrum corresponds to absorption by oxygen atoms in the WHIM contained in the Sculptor Wall. The characteristics of the absorption are consistent with the distance of the Sculptor Wall as well as the predicted temperature and density of the WHIM. This result gives scientists confidence that the WHIM will also be found in other large-scale structures.

This result supports predictions that about half of the normal matter in the local Universe is found in a web of hot, diffuse gas composed of the WHIM. Normal matter — which is different from dark matter -- is composed of the particles, such as protons and electrons, that are found on the Earth, in stars, gas, and so on. A variety of measurements have provided a good estimate of the amount of this "normal matter" present when the Universe was only a few billion years old. However, an inventory of the nearby Universe has turned up only about half as much normal matter, an embarrassingly large shortfall.
http://asterisk.apod.com/viewtopic.php?t=19435

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Missing Matter?

Post by The Code » Thu May 13, 2010 3:47 pm

Hi Folks

Did we not have this discussion before? I went right back, and only found missing Energy. Oh well.

Question:

With out seeing the before and after photo, How do you come up with, there's something missing here?


http://www.universetoday.com/2010/05/11 ... more-64242

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Re: Missing Matter?

Post by bystander » Thu May 13, 2010 4:04 pm

mark swain wrote:How do you come up with, there's something missing here?


http://www.universetoday.com/2010/05/11 ... -universe/
Maybe you ought to read the article
This result supports predictions that about half of the normal matter in the local Universe is found in a web of hot, diffuse gas composed of the WHIM. Normal matter — which is different from dark matter — is composed of the particles, such as protons and electrons, that are found on the Earth, in stars, gas, and so on. A variety of measurements have provided a good estimate of the amount of this "normal matter" present when the Universe was only a few billion years old. However, an inventory of the nearby Universe has turned up only about half as much normal matter, an embarrassingly large shortfall.

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Re: Missing Matter?

Post by Chris Peterson » Thu May 13, 2010 4:24 pm

mark swain wrote:With out seeing the before and after photo, How do you come up with, there's something missing here?
I'm not quite sure what you are asking. It is believed, on theoretical grounds, that normal matter makes up about 5% of the Universe. But only about half of that is actually observed; the rest is the so-called "missing matter".

This image is just an artist's rendering, showing how this matter (or some of it, at least) has been detected. It is too diffuse to produce a detectable x-ray emission, but it does show up as absorption lines in the spectrum of a hot background source.

It was also reported recently that by looking at the sky using wavelengths other than those which have traditionally been used, some of this missing matter is seen in distant galaxies.
Chris

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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by The Code » Thu May 13, 2010 4:44 pm

Thanks Chris

Yeah, Its was this bit that through me.
bystander wrote:However, an inventory of the nearby Universe has turned up only about half as much normal matter, an embarrassingly large shortfall.
End of the line... no more to read.

I could have continued, But as my question found its self berried under the rubble, of another part of the forum, I will not bother.

Mark
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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by Beyond » Wed May 19, 2010 4:53 am

Whim contains about half the matter in the universe and its hot??

What happened to the tempreture of space being down to about absolute zero??

It looks like its a good thing there is all that cold to counteract all that hottness, or we would have been "well done" a long time ago.

Also, its a good thing that there's all that hot out in space to counteract all that cold thats there, or we would have been "Humancicles a long time ago!

:idea: what would we have if there was no HOT or COLD out there in space?
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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by neufer » Wed May 19, 2010 11:35 am

beyond wrote:Whim contains about half the matter in the universe and its hot??

What happened to the temperature of space being down to about absolute zero??
Cosmic microwave background radiation is a cold (2.7K) collision-less photon "bath."

WHIM is a hot but collision-less gas.

Cosmic rays are an extremely hot but collision-less plasma.

All these things live in peaceful coexistence because they don't interact (much).
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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by Chris Peterson » Wed May 19, 2010 1:02 pm

beyond wrote:What happened to the tempreture of space being down to about absolute zero??
Space has no temperature in any reasonable sense of the word. Particles of matter have a temperature, and that is what is being described as hot. There is also radiation passing through space, which while it has no temperature, comes from material that does, and which can transfer energy into other material, heating it.
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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by neufer » Wed May 19, 2010 1:25 pm

Chris Peterson wrote:
beyond wrote:What happened to the tempreture of space being down to about absolute zero??
Space has no temperature in any reasonable sense of the word.
Particles of matter have a temperature, and that is what is being described as hot.
Photons & particles of matter all have specific energies (vis-a-vis the Cosmic microwave background).

Collections of photons & particles of matter can be said to have a temperature corresponding to their random energies.
Chris Peterson wrote:There is also radiation passing through space, which while it has no temperature, comes from material that does,
and which can transfer energy into other material, heating it.
Cosmic microwave background radiation comes from the big bang plasma
and its photons can absorb energy from high energy cosmic rays thereby cooling it.
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Re: CXC: X-ray Discovery Points to Location of Missing Matte

Post by Chris Peterson » Wed May 19, 2010 4:47 pm

neufer wrote:Collections of photons & particles of matter can be said to have a temperature corresponding to their random energies.
Classically, "temperature" applies to matter. In the thermodynamic sense, photons have no temperature. You can use the Boltzmann constant to derive a temperature equivalent from the photon energy, but that really isn't a temperature in the usual sense.
Cosmic microwave background radiation comes from the big bang plasma and its photons can absorb energy from high energy cosmic rays thereby cooling it.
Yes, photons can either absorb or emit energy, which means they can either heat or cool surrounding matter. In the lab, lasers are used to cool particles to very near absolute zero.
Chris

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