Computer Model Points To the Missing Matter

eldavojohn writes "There exists a little-known problem of missing regular matter that has perhaps been overshadowed by the mysteries of dark matter and dark energy. Computer models show that there should be about 40% more regular matter than we see... so where is it? From the article: 'The study indicated a significant portion of the gas is in the filaments — which connect galaxy clusters — hidden from direct observation in enormous gas clouds in intergalactic space known as the Warm-Hot Intergalactic Medium, or WHIM, said CU-Boulder Professor Jack Burns... The team performed one of the largest cosmological supercomputer simulations ever, cramming 2.5 percent of the visible universe inside a computer to model a region more than 1.5 billion light-years across.' This hypothesis will be investigated and hopefully proved/disproved when telescopes are completed in Chile and the Antarctic. The paper will be up for review in this week's edition of the the Astrophysical Journal."

Comments

Bad name.

[morgan_greywolf]

Warm-Hot Intergalactic Matter? WHIM? The WHIM Hypothesis? I mean, it just SOUNDS like he made it up on whim!

Re:Bad name.

[networkBoy]

It's all moot anyway:

cramming 2.5 percent of the visible universe inside a computer In other news the computer coalesced into a black hole and devoured the solar system, Al Gore included. It then spit out his belt. News at 11.
-nB

Check behind the couch.

[Anonymous Coward]

That's where my missing matter always turns up.

Re:Oh! Oh!

[zappepcs]

err... the answer is .... 42!

Packing Penuts

[jameskojiro]

The missing matter is in those Packing peanuts that the scientist's equipment was shipped with.

Not Dark Matter

[iamlucky13]

Since I'm sure the question will be asked, no this missing mass is not dark matter, as both the summary and the article are clear to emphasize. I wanted to repeat that. The primary evidence for dark matter is the galactic rotation curves. The article is talking about gaseous normal matter that we believe exists, but hasn't spotted yet. This missing gaseous matter is nowhere near sufficient in mass to explain the gravitational effect of dark matter and is being looked for on a scale larger than galaxies. The missing mass is an estimate 2% of the mass of the universe, whereas dark matter is an estimate 25%.

Also, I though it interesting that the is a very interesting rendition of the nearby universe. It's not related to the article, but it does show the filamentary structure the article talks about.

Re:Not Dark Matter

[explosivejared]

Right on, the matter the article discusses matter that should be there as pointed out in the Dirac equation. The universe should, based on theory, be made up of a certain percentage of baryons (three quark particles).

Re:Not Dark Matter

[Chosen Reject]

no this missing mass is not dark matter

You can say that again. It's mostly a transparent green haze from what I can see of it. The guy sitting in the next cubicle just found a good amount of that Warm-Hot gas and has released it into the workplace.

Re:Not Dark Matter

[scapermoya]

very true. this dark matter does not need to be special in any way, it can be dust. but it has to be right around galaxies for the rotation curves to work out. there simply aren't enough stars to account for the way our (and every other) spiral galaxy behaves relatively far from its center. dark energy on the other hand is a different (and unrelated) story.

Re:Not Dark Matter

[fnordboy]

That's not correct. The article discusses matter that should be there as pointed out by the http://en.wikipedia.org/wiki/Friedmann_equations/Friedmann equations and similar equations that describe the http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation cosmic microwave background. The Dirac equation doesn't say anything about the composition of the universe.

Re:Not Dark Matter

[scapermoya]

i think with the current evidence, it is safe to say that most dark matter is strictly non-baryonic (the mass we are used to). there is no doubt, however, that dust and other baryonic matter in all kinds of forms (clouds of gas, dwarf stars, planets, you name it) contribute to dark matter. what we must quibble about now is the amounts, the proportions.

by the way, dust doesn't just spontaneously emit radio waves. if that were true, all the dust on our planet would likely make radio stations impossible. there are plenty of places dust could be where it doesn't reflect light, or emit radiation due to absorption. in fact, dust contributes more to our inability to see our whole galaxy than anything else.

Re:Not Dark Matter

[fnordboy]

Ok, fair point - there are a lot of little, dense things like brown dwarfs and planets that we can't currently observe. However, these can only be a tiny component of the "dark" stuff that we don't see. If brown dwarfs or planets comprised a significant chunk of the dark matter, it would be detected by gravitational microlensing events, and those observations suggest that dense baryonic objects (such as stars, brown dwarves, etc.) aren't a big (which is to say, dynamically important) component of the galactic halo.

Also, with respect to dust, it's actually quite easy to detect it in the interstellar medium, in both emission and absorption. It doesn't ALWAYS emit radiation, and doesn't do it spontaneously, but when dust is bombarded by light from nearby stars, it tends to re-emit in the infrared and radio. So it's incredibly easy to detect it in both of those bands, and use it to learn things about galaxies. It blocks optical light, of course, so you can see it in nearby (and not so nearby) gas-rich galaxies.

I see by the link below your name that you're from Berkeley, or at least probably have some berkeley ties. You should go talk to Chris McKee in the astronomy department if you think dust is more of a pain than it's worth - he'll set you straight!

Re:Not Dark Matter

[iamlucky13]

Sorry if I'm misreading your post, but what I was saying in my original post is that the matter the article is dealing with is a completely separate issue in astronomy from dark matter. You seem to be interpreting it as saying dark matter is probably actually normal matter. I won't get into that debate here but just want to clarify that this is not what either the paper or I was suggesting.

Dark matter was detected gravitationally and generally believed to be non-baryonic. The matter in question has not been detected at all, but is thought to exist based on the current models of how the universe was formed. Dark matter appears to make up 25% of the mass/energy in the universe. The matter the article discusses in only about 2%.

Also, from my interpretation of the article and prior reading, it shouldn't be dust, but simply vast clouds of mostly hydrogen and some helium gas. This stuff would reside in the huge volumes of space between the galaxies and would never have achieved sufficient densities to collapse into stars where it could be fused into the heavier atoms necessary to form space dust. At the distances, densities, and temperatures involved, it would be undetectable with our current technology.

And of course, there is free gas and dust that we are able to see in the Milky Way and neighboring galaxies, but this also is a separate issue.

I think I know where it will be found

[hyades1]

"...hidden from direct observation in enormous gas clouds in intergalactic space..." >p>

If all that missing matter is contained in gas clouds, I think I know where to find it. There's an election coming up, right?

missing matter != dark matter?

[Hatta]

I was under the impression that dark matter was, by definition, matter we can not detect. So I don't understand how there can be "regular" matter that's hidden. If you can't see it, how do you know it's there? Well you can detect its gravity, but that's how we detect dark matter. So how do you distinguish this stuff from the dark matter? What's the difference?

Re:missing matter != dark matter?

[belthize]

    Dark Matter is matter that's not made up of normal baryonic material. As a matter of fact you can detect it but not enough to matter.

    Over and above the missing 'dark matter' there's the matter of the missing regular matter.

    It's the missing regular matter that matters in this case.

Belthize

Re:missing matter != dark matter?

[Intron]

I explained to my bank that my computer model showed 40% more money in my account than they listed. For some reason they refused to listen to me.

Re:missing matter != dark matter?

[Bryan K. Feir]

There's this story from a while back, which pointed to at least one case where the non-baryonic dark matter reacted differently from the baryonic matter. There was a galactic collision, and the non-baryonic matter sort of coasted on while much of the baryonic gas slammed together in the middle. Since non-baryonic dark matter reacts only to gravity, there are ways to distinguish between the two...

IBM = Incredibly Big Machine

[butterwise]

cramming 2.5 percent of the visible universe inside a computer

That is one big-ass computer.

Re:IBM = Incredibly Big Machine

[jddj]

All you need is a suitable improbability generator - say, a nice hot cup of tea - and a piece of fairy cake...

Poll: Location of Missing Matter

[davidwr]

Poll: Where will scientists find the missing matter?

* It's not missing. Our measurements are wrong.
* It's not missing. Our theories are wrong.
* In filaments between the galaxies.
* In an as-yet-undiscovered construct.
* In CowboyNeal's sock drawer.

Computer model?

[phatvw]

I reckon this is a wee bit offtopic, but it struck me - are there any scientific models that are not "computer models"? It used to be the case that if it was a computer model, you'd think, "Ooooh they are using computers, they must be smart". But now?

This stuff is absolutely fascinating. Good stuff from Colorado as always.

The answer is obvious!

[greg_barton]

...there should be about 40% more regular matter than we see... so where is it?

Behind you...