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Chandra Discovers "Rivers Of Gravity" That Define Cosmic Landscape
ScienceDaily Magazine ^ | Thursday, August 01, 2002 | Editorial Staff

Posted on 08/02/2002 4:41:48 PM PDT by vannrox

Reprinted from ScienceDaily Magazine ...

Source:             NASA/Marshall Space Flight Center
Date Posted:    Thursday, August 01, 2002
Web Address:   http://www.sciencedaily.com/releases/2002/08/020801080835.htm


Chandra Discovers "Rivers Of Gravity" That Define Cosmic Landscape

NASA's Chandra X-ray Observatory has discovered part of an intergalactic web of hot gas and dark matter that contains most of the material in the universe. The hot gas, which appears to lie like a fog in channels carved by rivers of gravity, has been hidden from view since the time galaxies formed.

"The Chandra observations, together with ultraviolet observations, are a major advance in our understanding of how the universe evolved over the last 10 billion years," said Fabrizio Nicastro, leader of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and head of one of the teams of scientists involved in the discovery.

Four independent teams of scientists, whose results appear as separate papers in the Astrophysical Journal, used Chandra to detect intergalactic gas with temperatures ranging from 300,000 to 5 million degrees Celsius. This gas forms part of a gigantic system of hot gas and dark matter that defines the cosmic landscape. The gaseous component alone contains more material than all the stars in the universe.

"We had strong suspicions from the Big Bang theory and observations of the early universe that this gas exists in the present era, but like a stealth aircraft it had eluded our detection," said Claude Canizares of the Massachusetts Institute of Technology (MIT), Cambridge, who along with Taotao Fang, also of MIT, led of one of the teams.

The hot gas detected by Chandra can be used to trace the presence of the more massive dark-matter component. The discovery of the hot gas may eventually enable astronomers to map the distribution of dark matter in the universe and perhaps understand its origin.

Ultraviolet telescopes had detected cooler components of the hot gas system, but because of its high temperatures most of it is detectable only with an extremely sensitive X-ray telescope. The various groups used two techniques to probe the intergalactic gas. One method uses the absorbing effects of the gas on X-rays from distant galaxies.

On their way to Earth, the X-rays from a distant quasar dim as they pass through a cloud of the intergalactic gas. By measuring the amount of dimming due to oxygen and other elements in the cloud, astronomers were able to estimate the temperature, density and mass of the absorbing gas.

Observations of the quasars PKS 2155-304 by the MIT and Harvard-Smithsonian groups, and H1821+643 by a group from Ohio State, Columbus, revealed various parts of the hot gas system. One of these appears to be a filament in which the Milky Way and Andromeda galaxies are embedded, whereas other detected portions are at distances of a few billion light- years from Earth.

These results confirm earlier work by Joel Bregman and Jimmy Irvin of the University of Michigan in Ann Arbor, who flipped the normal procedure, and used the fact that the hot gas is itself a source of X-rays. By observing the absorption of X- rays from the hot gas by a foreground galaxy, they were able to deduce the presence of hot gas behind the galaxy.

"Normally the doctor studies the X-ray shadow produced by your bones to learn about your bones," said Bregman. "In essence, we used the shadow to learn about the X-ray machine."

During the first few billion years of the universe, about 20 percent of the matter came together under the influence of gravity to form groups and clusters of galaxies. Theories predict that most of the remaining normal matter and dark matter formed an immense filamentary web connecting the groups and clusters of galaxies, predicted to be so hot that it would be invisible to optical, infrared and radio telescopes.

"Computer simulations have been telling us for several years that most of the 'missing' gas in the universe should be in hot filaments," said Smita Mathur, leader of the Ohio State team. "Most of those filaments are too faint to see, but it looks like we are finally finding their shadows."

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor. The Smithsonian's Chandra X- ray Center controls science and flight operations from Cambridge, Mass.

Images and additional information about this result are available at:

http://chandra.harvard.edu

and

http://chandra.nasa.gov


TOPICS: Culture/Society; Extended News; Government; News/Current Events
KEYWORDS: chandra; cosmic; darkenergy; darkmatter; goliath; gravity; haltonarp; landscape; nasa; observatory; realscience; space; stringtheory; theory; xay
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1 posted on 08/02/2002 4:41:48 PM PDT by vannrox
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To: vannrox
Since these articles started appearing on FR, I have been wondering about the 'rivers of gravity' thing. Still don't know what they are talking about.
2 posted on 08/02/2002 4:43:55 PM PDT by RightWhale
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To: vannrox
"In a subsequent announcement, NASA said that they will soon unveil the Mountains of Mashed Potatoes on various planets in the solar system........."
3 posted on 08/02/2002 4:43:59 PM PDT by RightOnline
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To: vannrox
Imagine by disappointment that this was not about Chandra Levy.
4 posted on 08/02/2002 4:50:18 PM PDT by crystalk
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To: vannrox; Physicist
Again, I call on Physicist to make matters clear for a common man.

I did not know that gravity was subject to remote detection, like X-Rays or Infrared.

Thanks ahead of time, Physicist.

5 posted on 08/02/2002 4:50:36 PM PDT by LibKill
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To: vannrox
"From the rivers of Gravity,
Where we sat down.
And we wept, when we remembered Orion."
6 posted on 08/02/2002 4:52:27 PM PDT by tet68
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To: tet68
Lol!
7 posted on 08/02/2002 5:11:27 PM PDT by sheik yerbouty
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To: *Space; *RealScience
.
8 posted on 08/02/2002 5:14:35 PM PDT by Libertarianize the GOP
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To: 2sheep; Thinkin' Gal
bump
9 posted on 08/02/2002 5:16:23 PM PDT by Zad
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To: LibKill
I don't think this is what these scientists have discovered but gravity is definitely detected remotely. Massive galaxies (probably with black holes) bend light passing near them so we see multiple images of the galaxies behind them. Many examples have been posted on the "astronomy picture of the day" site - a worthwhile site for 2 minutes per day of learning.
10 posted on 08/02/2002 5:19:32 PM PDT by RossA
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To: RossA; Physicist
Very good. And I know that light bends around a massive object (please don't expect me to explain why, I could never do the math).

I called upon Physicist because he has a real ability to explain these things to a poor barbaric SOB like me.

11 posted on 08/02/2002 5:24:23 PM PDT by LibKill
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To: RossA
P.S. APOD is one of my favorite sites, every day.
12 posted on 08/02/2002 5:25:25 PM PDT by LibKill
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To: RightWhale
Since these articles started appearing on FR, I have been wondering about the 'rivers of gravity' thing. Still don't know what they are talking about.

Maybe they should call it rivers of mass or matter instead, but what the astronomers are seeing is the effect of gravity from the mass. The dark matter in the universe forms a spongy structure similar to bone marrow. The "rivers" they are seeing is the connective fibers, which are so large from our perspective I guess it's appropriate to call them rivers.

13 posted on 08/02/2002 5:42:55 PM PDT by Moonman62
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To: Moonman62
Okay. I had a mental image of gravity being there already, --potential wells--, in these filaments and attracting dust and gas. Makes more sense this way.
14 posted on 08/02/2002 5:47:30 PM PDT by RightWhale
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To: LibKill; RossA
They don't detect the gravity per se.

There's a certain amount of deduction going on here. Theory (meaning computer simulations) tells them that there should be self-gravitating streams of hot gas between the galaxies.

You can get a taste of what these streams look like and how they form in a couple of simulations I ran using the National Scalable Cluster Project supercomputers here at Penn, using parallel code written by Prof. Paul Bode.

Since they expect the streams to be there, they set about to detect them by looking at the spectra of distant quasars. Since there are so many streams, they reasoned that some quasars must end up behind streams, from our point of view. In that case, the streams will block out part of the light from the obstructed quasars in a characteristic way in the x-ray band. This obstruction is what they have detected.

Note that this doesn't allow them to image the streams themselves; they just see the effect of the streams at a small number of points on the sky. They call them streams because that's what they expected to see. The same data might support the hypothesis that there are big gasseous blobs out there. But either way, the total mass of the gas can be estimated, and it is non-negligible.

15 posted on 08/02/2002 5:52:42 PM PDT by Physicist
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To: RossA
FWIW, I don't think that gravitational lensing plays an important role in this analysis. There's a lot of matter in these streams, but it's not as concentrated--by many orders of magnitude--as it is in a galaxy. What it lacks in density it makes up for in volume, however.
16 posted on 08/02/2002 5:59:43 PM PDT by Physicist
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To: LibKill
While Physicist is explaining things to us less experienced, he could also explain the accuracy of these findings. Since, as I understand it, the satellite detects something, converts it to a digital (programmer dictated) equivalent,which is then transmitted to earth and displayed (to the programmers dictates) graphicly.

It seems to all depend on what the programmer expects and programs for, not what may actually be detected.

Just like tomographs are only as good as the base data the programmer works with.

Have I confused everybody as bad as I confused myself ?

The point I'm trying to make is: How good is the interpetive data ?

17 posted on 08/02/2002 6:00:27 PM PDT by leadhead
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Comment #18 Removed by Moderator

To: crystalk
Imagine my disappointment that this was not about Chandra Levy

Now there's a statement on our culture.

"Oooh! Oooh! Juicy tidbits about brutal death of some woman I've never met! Yeah...oh, darn. It's just a dumb post about the nature and origins of the universe. BOOOOORINNNNNG."

(Just a joke, no personal jab intended, no purchase necessary, batteries not included)

19 posted on 08/02/2002 6:08:44 PM PDT by pupdog
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To: Physicist
Thank you, Physicist.

I count on you for no-BS facts.

If I fail to understand those facts, well that is my failing.

20 posted on 08/02/2002 6:12:02 PM PDT by LibKill
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To: Physicist; ThinkPlease; RadioAstronomer
Any thoughts on how this "hot gas" got to be so hot, and why it hasn't radiated most of it's heat out into the surrounding Universe?

Also, is it thought that the "hot gas" is still being heated? If so, what's the mechanism and source of energy to heat it?

Thanx...

21 posted on 08/02/2002 6:12:36 PM PDT by longshadow
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Comment #22 Removed by Moderator

Comment #23 Removed by Moderator

To: Physicist
The latest Scientific American has a cover story along the lines of "Do We Really Need Dark Matter?" If it lies in rivers and pulls ordinary matter with it, does that mean we do? (The proposed alternate theory revises Newtonian dynamics so that less force is needed to produce very small accelerations.)
24 posted on 08/02/2002 6:39:02 PM PDT by VadeRetro
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To: leadhead
The point I'm trying to make is: How good is the interpetive data ?

Well, I addressed that to a certain extent in my first post. Here's what they do know: at a small number of specific sample points in the universe, they can measure the extinction function of x-rays, and find that there is a large amount of non-luminous matter in the universe in that direction. That's it. The statistical behavior and amount of extinction agree with what is predicted for gaseous (correct spelling this time) stream of a certain size, density and composition.

The headline of this story is misleading, and is almost certainly not how the scientists couched it in their publication. They probably said something like, "gaseous streams of a certain description are predicted by theory; we have now tested some of these predictions, and they have passed."

25 posted on 08/02/2002 6:44:19 PM PDT by Physicist
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To: LibKill
If I fail to understand those facts, well that is my failing.

It's only your failing if you don't keep asking about what you don't get. Keep firing away and eventually I'll find the right words!

26 posted on 08/02/2002 6:48:24 PM PDT by Physicist
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To: Confederate Keyester
Why Do Astronomers Ignore Electrical Phenomena?

Because matter is electrically neutral on average. This means that the multipole moments of an electric field will be small up to a very large order. Magnetic fields, on the other hand, can have gigantic dipole fields over large distances, but of course these are not ignored by astronomers.

27 posted on 08/02/2002 6:53:40 PM PDT by Physicist
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To: longshadow
Good questions. I don't know the answers.
28 posted on 08/02/2002 6:59:04 PM PDT by Physicist
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Comment #29 Removed by Moderator

Comment #30 Removed by Moderator

To: VadeRetro
The latest Scientific American has a cover story along the lines of "Do We Really Need Dark Matter?" If it lies in rivers and pulls ordinary matter with it, does that mean we do?

It seems that we do in any case. You can set limits on the density of baryonic matter (i.e. normal matter, made of protons and neutrons) by looking at the relative abundances of the lightest nuclei (hydrogen, deuterium, helium and lithium). If there are too many baryons (protons and neutrons) around, it becomes impossible to construct a model of Big Bang nucleosynthesis that can be reconciled with the abundances we observe.

(The proposed alternate theory revises Newtonian dynamics so that less force is needed to produce very small accelerations.)

I wouldn't call MOND a theory. It's more of an empirical fit.

31 posted on 08/02/2002 7:09:47 PM PDT by Physicist
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Comment #32 Removed by Moderator

To: longshadow
Also, is it thought that the "hot gas" is still being heated? If so, what's the mechanism and source of energy to heat it?

Democrats.

33 posted on 08/02/2002 7:13:11 PM PDT by VadeRetro
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Comment #34 Removed by Moderator

To: vannrox
Hot gas...dark matter, is this toilet humor? heh heh
35 posted on 08/02/2002 7:22:59 PM PDT by wattsmag2
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To: vannrox
an immense filamentary web

Hmm, sounds a little liek the "Alderson tramlines" in Pournelle's CoDominum universe, the one that includes the "Mote in God's Eye", and the "The Gripping Hand"

36 posted on 08/02/2002 7:29:56 PM PDT by El Gato
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Comment #37 Removed by Moderator

Comment #38 Removed by Moderator

To: Physicist
I wouldn't call MOND a theory. It's more of an empirical fit.

Which originator of the "fit", who is also the author of the SciAmer. article, admits. Upon reading the article, I wondered about some sort of quantum gravity effect at very low levels of graviation. But that's just idle speculation. I certainly don't have the mathematical background to even attempt to investigate the idea.

39 posted on 08/02/2002 7:39:13 PM PDT by El Gato
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To: RadioAstronomer
And a ping for you, too.
40 posted on 08/02/2002 7:41:05 PM PDT by Physicist
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Comment #41 Removed by Moderator

To: longshadow
Any thoughts on how this "hot gas" got to be so hot, and why it hasn't radiated most of it's heat out into the surrounding Universe?

Also, is it thought that the "hot gas" is still being heated? If so, what's the mechanism and source of energy to heat it?

There is also very hot gas that surrounds clusters of galaxies, which also implies the presence of dark matter. I think the gas is heated by supernovas and such. Perhaps some of that hot gas is siphoned off by the dark matter filaments, but that's just a guess.

42 posted on 08/02/2002 8:12:25 PM PDT by Moonman62
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To: vannrox
Hot gas? Dark matter? Great density? Are they sure they didn't turn their telescopes on Congress by accident?

After all, Li'l Tommy Daschle is definitely a "red dwarf" though not as much so as the 3 1/2 Reich who is running for Governor in Massachusetts.

Congressman Billybob

Click for: "Memo to Li'l Tommy Daschle: 'You're Busted.'"

43 posted on 08/02/2002 8:21:17 PM PDT by Congressman Billybob
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To: RightWhale
GooGle Goes in search of Rivers of Gravity The capillaries of the universe
44 posted on 08/02/2002 8:30:03 PM PDT by NormsRevenge
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To: Confederate Keyester
Thanks for the background on plasmas. The local university is strong in plasma research, and I might find this an opportunity to combine cosmology and this strength into my degree program. We'll see how it goes, there is still some preparation to be done before I would be ready to start.
45 posted on 08/02/2002 8:45:30 PM PDT by RightWhale
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Comment #46 Removed by Moderator

To: vannrox
I know there's a Chandra Levy joke in here somewhere.
47 posted on 08/02/2002 9:21:16 PM PDT by 3catsanadog
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To: LibKill
Gravity is not a universal constent and all matter, no matter how small has an electro magnetic field...which in turn generates gravity of sorts...or micro gravity. So, if you put all this gas into one area, it's density would create gravity of sorts....which in turn also causes pressure and which in turn creates more friction heat...etc. Does that help?
48 posted on 08/03/2002 12:37:25 AM PDT by Stavka2
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To: LibKill
Light bend around it because photons of energy are pulled in by the gravitational pull...or in another way to explain it...take a water mellon and put in on a soft mattress...then roll a marble by it. The marble will roll into the indented area around the mellon....that's what mass does to the space...it bends it...pulling lighter objects into its orbit/self.
49 posted on 08/03/2002 12:40:36 AM PDT by Stavka2
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To: LibKill
Light bend around it because photons of energy are pulled in by the gravitational pull...or in another way to explain it...take a water mellon and put in on a soft mattress...then roll a marble by it. The marble will roll into the indented area around the mellon....that's what mass does to the space...it bends it...pulling lighter objects into its orbit/self.
50 posted on 08/03/2002 12:40:36 AM PDT by Stavka2
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