Scientists Find Missing Matter

4 Feb, 2005 at 12:31am ET Article published in Tech

For years, astrophysicists have been boggled by the fact that the grand sum of all the known “normal” matter in the universe — that which makes up the stars, the Earth and even our own bodies — only amounts to half of what should exist based on computer simulations. Given that multiple simulations have continually yielded the same result, they theorized that the rest of the normal matter, known as baryons, must be hiding somewhere in the space between galaxies. However, they haven’t had much evidence to support the theory until now.

A new study conducted with the help of the Earth-orbiting Chandra X-ray Observatory has revealed the existence of baryons in at least two giant, intergalactic clouds of super-hot gas 150 million and 380 million light-years from our planet.

The study, which appears in the Feb. 3 issue of the journal Nature, shows how certain wavelengths of X-rays emitted from a distant galaxy in the constellation Ursa Major are being absorbed by the two clouds. The absorption pattern, as detected by Chandra, is consistent with interference caused by carbon, neon, nitrogen and oxygen ions — in other words, baryons.

When the study’s authors extended the number of baryons in the two clouds to account for the volume of all the intergalactic clouds in the universe, the resulting figure equaled that of the missing matter from their computer simulations.

Source: Wired

Comments

4 Feb 2005 ~ 1:11am primesuspect Most of you probably don't realize what a fantastic discovery this is....

Suffice to say, it's REALLY big.

[/astronomy nerd]
4 Feb 2005 ~ 1:13am Thrax Baryon sweep! ^ ^
4 Feb 2005 ~ 1:25am entropy So now how are they going to explain their anti-matter excuse? I know that there's *some* out there, but they were claiming that it was everywhere, mainly because they couldn't get their equations to balance. Interesting.
4 Feb 2005 ~ 2:35am RWB Someone care to explain this in lamens terms??? I ain't much of a lamen, but I ain't no Thrax.
4 Feb 2005 ~ 3:05am Thrax Was that a compliment or an insult?

/me gives a bewildered look

Both?
4 Feb 2005 ~ 7:04am Medlock Exactly how "big" of a discovery is this?

RWB wrote:

Someone care to explain this in lamens terms??? I ain't much of a lamen, but I ain't no Thrax.

Haha, I think he meant, "I'm not an idiot, but I'm not quite as smart as Thrax is."
4 Feb 2005 ~ 12:16pm GHoosdum

entropy wrote:

So now how are they going to explain their anti-matter excuse? I know that there's *some* out there, but they were claiming that it was everywhere, mainly because they couldn't get their equations to balance. Interesting.

I think you're referring to 'dark matter'? I guess it depends on how much baryonic mass they find - they might give up the dark matter hypothesis.
4 Feb 2005 ~ 12:56pm Gobbles

entropy wrote:

So now how are they going to explain their anti-matter excuse? I know that there's *some* out there, but they were claiming that it was everywhere, mainly because they couldn't get their equations to balance. Interesting.

During the original big bang, matter and anti-matter were released, as both cannot exist at the same time it crashed into each other destroying both matter and the anti-matter, the universe as we know it is made up of the surviving matter as there was more matter than anti-matter. Thats kinda the lamens answer. I watch alot of the science channel on dish network. That what Sam Niel the narrator told me on the subject of anti-matter. We all know that whats on the moving picture box it the truth..
4 Feb 2005 ~ 1:21pm deicist amazing what you can find down the back of the sofa isn't it?
4 Feb 2005 ~ 4:49pm RWB

TheGr81 wrote:

Exactly how "big" of a discovery is this?

Haha, I think he meant, "I'm not an idiot, but I'm not quite as smart as Thrax is."

Pretty much yeah....
4 Feb 2005 ~ 5:39pm Thrax This discovery is.. well.. Huge.

First it gives more meat to the theory of "Dark Matter" (So called because scientists had NO idea what to call it), which has practically dominated spacial theory to explain all the unaccounted matter in the universe. The theory was first developed by a swiss astrophysicist named Fritz Zwicky (What a name!) in 1933.. Tiptoeing around the nitty gritty details, the theory evolved to explain a particle matter that could not be detected by its radiation signature, yet can be inferred to exist because of gravitational effects observed on other stars and galaxies. Zwicky estimated the total amount of mass in a cluster of galaxies (The coma cluster, I think it was) based on the motions of the galaxies near the edge of them. When he compared the estimate he had made to a mathematical estimation based on the number of galaxies and the total brightness of those galaxies, he found that his estimation contained about 400 times more mass than what was mathematically predicted (Lordy I don't know how you predict mass from galactic movement). The equation to explain galactic mass and matter was subsequently changed, and now scientists are left fumbling to fill in the blanks on the paper.. And as of yet, we can't.

At any rate, as the theory evolved, scientists have struggled and stumbled over the sizeable differences between the mathematical estimation of the galaxy's mass, and the practical estimation of the galaxy's mass. Which one's right? We've never been able to prove the existence of dark matter before, we could only infer it exists, so we couldn't rule out the math. Yet the math didn't match up with what was being observed, so we couldn't discount dark matter. Without trying to throw too many stupid physics acronyms at you guys at once, two theories emerged to explain what dark matter is:

The first is baryonic matter, such as brown dwarf stars, or even smalls dense chunks of heavy elements called massive compact halo objects (MACHOs). Studies of something called the "Big Bang nucleosynthesis" (I don't know what that really is, yet) have suggested that MACHOs can't be more than a small fraction of dark matter (Roughly 4%). The other, and more common view is that dark matter is made primarily of one more more basic particles other than electrons/neutrons/protons. The most commonly-suggested particles are neutrinos, axions, SIMPs (Strongly Interacting Massive Particles) and WIMPs (Weakly Interacting Massive Particles). The theories both interrelate and contradict if I understand them correctly.

What scientists discovered as a result of studying NGC 4555 (One of the galaxies in question), is that its gasseous halo is twice the size of the optical galaxy. What's keeping the galaxy in its eliptical shape? Why doesn't the gas float away or get contracted into the galaxy's core? Scientists concluded that it's dark matter. According to gravitational mathematics (Observing the galaxy and deriving a mass/matter total from its movement) the total mass of the dark matter halo is about ten times the combined mass of the stars in the galaxy, and about 300 times the mass of the infrared gas cloud. The mass of the galaxy itself, and the gravitational forces exhibited by the sum of NGC 4555's stars is FAR less than the force required to hold such a massive and isolated galaxy together. So what gives? What this study really proves (Finally getting around to the point), is that "Baryonic filaments" (Thin strings of protons/neutrons/electrons) are connected to real dark matter. If the dark matter clouds that the filaments appear to be connected to weren't there, the baryons would be absorbed into galaxies and the galaxies into each other. Something is keeping our galaxies apart and contained in their shapes, and the theory of dark matter was just made quite a bit more credible.

//EDIT: Can you confirm my analysis of the situation, Prime? I try to wrap my head around all the theories all the time, I'm pretty sure I got this one right.
5 Feb 2005 ~ 12:11am KingFish damn, and I thought they had just found jimmy hoffa
5 Feb 2005 ~ 11:19am mmonnin Galaxies are ever expanding from the Big Bang and will continue to do so for who knows how long. And gravity keeps the galazies together. Last time I read stuff like this scientists thought there could be a black whole in the middle of the Milky Way keeping the galazy together. I have no idea if thats true or not and it could very well be a wild guess.

I dont know what kind of formulas they are using to measure masses of whole galaxies but I could see how they could be way far off. That is no easy calculation.
5 Feb 2005 ~ 10:50pm RWB I've seen shows were they talk about the kind of calculations they do, and that most are usually the type that takes months to figure out, and if anything was calculated wrong, gotta start all over
5 Feb 2005 ~ 10:58pm diminion yes mmonnin, there is a supermassive(1-million to 1-billion solar-mass) black hole in the center of our galaxy. That is what controls the size of the galaxy. The more massive it is the bigger the galaxy. The black hole in our galaxy is a 3-4 million solar mass black hole. ALso i remember a part of my professors lecture that we can measure of galaxys mass by a formaula:
TotalMass=orbital size(A.U)3/orbital period(years)2
but before using it you have to find the galaxys rotation curve. He never went into how to calculate it.
If im wrong about something, my answer to you is that its been a while since i took the class.
6 Feb 2005 ~ 12:48am mmonnin It was a long time ago and it was just a guess when I heard. They cant really see that far but they could guess that something very massive needed to be in the center of the galaxy to hold it all together.

I guess its possible to calculate the size of the galaxy and its orbital period but damn, that has to be a bitch to calculate and figure out. I mean its not like you can take a meter stick out and measure it.