Dark Matter Stars in the Early Universe?

OriginalArlen writes "UniverseToday reports new research which suggests dark matter could have condensed to form 'dark stars' in the early universe. These stars would have been very massive and burned very slowly, fueled by non-fusion reactions, they could still be with us. Astronomers hope to better constrain theories of early galaxy and star formation with observations of gravitational lensing events caused by these ghosts of the primordial universe."

Comments

Nothing for you to see here. Please move along.

[Laebshade]

"Nothing for you to see here. Please move along."

Indeed.

Hmm... what if we discover a star like the one Asimov described in Nemesis? Yes, I know it wasn't a dark matter star, but they didn't see it, either.

Missing: Anything Provable

[RobertB-DC]

The whole article sounds like a solution in search of a problem. It talks about "Dark Matter" as though the mysterious substance's properties were well-defined, even going as far as positing stars fuelled by "dark matter annihilation, instead of nuclear fusion". And then TFA says "If these dark stars are stable enough, its possible that they could still exist today".

I propose that dark matter is actually composed of jellybeans and M&M's, and that the first massive objects were stars fuelled by the crushing force of the crunchy shells of the M&Ms piercing the relatively soft outer coating of the jellybeans. Gravitational separation eventually turned the masses into giant Cadbury Creme Eggs.

Other than being completely silly, am I making any fewer wild guesses than the Dark Matter Annihilation folks?

Re:Missing: Anything Provable

[OriginalArlen]

I propose that dark matter is actually composed of jellybeans and M&M's, and that the first massive objects were stars fuelled by the crushing force of the crunchy shells of the M&Ms piercing the relatively soft outer coating of the jellybeans. Gravitational separation eventually turned the masses into giant Cadbury Creme Eggs. Now you're just being silly. Imagine sphere with a radius of 1 AU (the size of earth's orbit, remember!) composed of milk chocolate and "fondant filling". The enormous pressures in the core would crush the crude, macroscopic proteins in the chocolate into their component molecules, then heat and pressure would eventually overwhlem the degeneracy pressure, causing the entire gooey mass to break down into a seething mass of elementary particles. This event also causes observable evidence, in the form of a huge burst of massless particles accelerated to relativistic velocities. These are called tic-tacs.

Re:Missing: Anything Provable

[megaditto]

this sounds like someone needed something to publish or perish.

An Arxiv paper doesn't really "count" as a publication for most purposes and certainly will not prevent you from "perishing" (that's what the peer-reviewed scientific journals are for).

Publishing in Arxiv is more like posting to a blog or slashdot where you semi-formally share your ideas and try to start up a discussion on the topic of interest to you.

Of course, some of the papers over there ended up being darn important.

Wouldn't they tend to collapse?

[LWATCDR]

Just wondering but if they are are massive and burn slowly wouldn't they tend to collapse into black holes? If they don't put out enough heat to counter their gravitational field they should collapse. If so they may be the cores of the super massive black holes at the center of many galaxies. Just and idea since there where no numbers given in the article.

Re:Wouldn't they tend to collapse?

[perturbed1]

What makes normal matter collapse is the "friction" or "interaction" between the charged particles. Dark matter is neutral as far as we know and it does not interact through the EM-forces. Hence the name "dark," meaning it does not interact with light either. It is hard to form models where dark matter "collapses". The reason is that the dark matter particles do not exchange energy/momentum easily, as they interact through the "weak" forces only.

Re:Wouldn't they tend to collapse?

[secPM_MS]

As matter clouds condenses, gravitational energy is released. This energy has to be radiated away for the collapse to proceed, as the collapse is opposed by the thermal kinetic energy of the matter in the cloud. This was a major problem in the early universe when the abundance of metals was so low that radiation cooling was less efficient. If dark matter interacts very weakly with normal matter and electromagnetic fields, cooling is going to be very slow indeed. We know that dark matter exists and that it forms concentrations on the scale of large galaxies. We do not have strong evidence for the concentration of dark matter in the solar system, where it could result in apparent radial variations in solar or planetary masses. I supect that cooling of stellar mass dark matter clouds is rather difficult. Once somebody figures out how to observe the stuff and its properties, we can better understand what we see and what we should be looking for.

Science and authors

[perturbed1]

On \. OriginalArlen reports the news. I look at the linked website, called Universe Today and I see that there is one "publisher" by the name of Fraser Cain. Following the link there, finally, I get to the article on the arxiv, the definitive source of new physics papers. So to get to the source, it takes three jumps. So what has Fraser Cain done for us? Watered down the content? Couldn't OriginalArlen read the article and write a gist himself/herself? Or is Fraser Cain the same person as OriginalArlen? Reading the original article, I find "some" correlation on what ends up on \. and what is in the article. Or is this not the point? If I had to write a review for this article, I would have said that the last sentence of the abstract is what is most important: "A ..star .. detectable via annihilation products (gamma-rays, neutrinos, anti-matter) possibly in combination with hydrogen lines." The brilliant thing about this article is that these theorists are cooking up something that is actually detectable! Something that can be tested and hopefully will! *Finally* congrats to Douglas Spolyar, Katherine Freese and Paolo Gondolo, who *wrote* the article. (No, I dont know any of them. But isn't it time we cited those whose ideas we regurgitate?)

Actual research link

[martyb]

If anyone can link the actual research done I'd love to see it

Here is the PDF: Dark matter and the first stars: a new phase of stellar evolution

Here is the abstract:

Douglas Spolyar1, Katherine Freese2,3, and Paolo Gondolo4
1 Physics Dept., University of California, Santa Cruz, CA 95064
2 Michigan Center for Theoretical Physics, Dept. of Physics, University of Michigan, Ann Arbor, MI 48109
3 Visiting Miller Professor, Miller Institute, University of California, Berkeley, CA 94720
4 Physics Dept., University of Utah, Salt Lake City, UT 84112
dspolyar@physics.ucsc.edu, ktfreese@umich.edu, paolo@physics.utah.edu

A mechanism is identified whereby dark matter (DM) in protostellar halos dramatically alters the current theoretical framework for the formation of the first stars. Heat from neutralino DM annihilation is shown to overwhelm any cooling mechanism, consequently impeding the star formation process and possibly leading to a new stellar phase. A "dark star" may result: a giant (> 1 AU) hydrogen-helium star powered by DM annihilation instead of nuclear fusion, and detectable via annihilation products (gamma-rays, neutrinos, antimatter) possibly in combination with hydrogen lines. (emphasis added)

Re:interesting

[MrFlibbs]

This aspect of dark matter has always been troubling. If dark matter reacts gravitationally with ordinary matter, shouldn't we find the two combined within some sort of object? Everyone talks about how dark matter explains galactic rotation and cluster movement, but no one seems to say anything about what happens when you mix them. Why wouldn't dark matter collapse into a stellar interior along with the ordinary matter? How would this affect the nuclear processes within the star?

Why would there be "stars" made entirely of dark matter, anyway? What keeps ordinary matter from falling in?

Dark Matter == Alien Civilizations

[Saeger]

A sufficiently advanced civilization that doesn't destroy itself first will inevitably optimize their environment to the point of harvesting every last drop of energy from their star(s), such that we can't detect anything but the gravitational effects.

This mysterious "dark matter" structure is termed a Matrioshka Brain (aka: Dyson Sphere).

I understand that this theory's still a bit too shocking for many to seriously consider, so "exotic particles" - or ANY other explaination - it must surely be.

Re:Dark Matter == Alien Civilizations

[StoneTempest]

Actually, if all of the dark matter were Dyson Spheres around stars, or star systems, they'd still give off black body radiation, which we can easily detect. This is because black body radiation is independent of everything except temperature, which will be above ambient interstellar temperature (thus producing the radiation) in every case, unless this civilization has found a way to reverse entropy.

Further, recent observations of a pair of colliding galaxies conclusively shows that dark matter absolutely cannot be normal matter, since normal matter interacts with the EM force (which is producing drag on the colliding gas clouds), but dark matter does not (in the collision the dark matter clouds are just sliding past each other). Thus Dyson Sphere-covered stars, or star systems, dark matter is not.

Dark Matter is the new Ether

[Leptok]

Does it seem weird to anyone else? Now I haven't stayed up to date with dark matter, but they keep insisting that it MUST be there. It almost seems to be the ether that was claimed to be around us before Einstein blew that one open.

Re:Dark Star

[__aaclcg7560]

Nope. Scientist confirms that Dark Stars was Lone Starr's Dad instead of Dark Helmet. No comment from Miss Universe on how that happen.

Re:interesting

[LionMage]

Pity there's no "-1 Factually Wrong" moderation.

The idea that the net sum product of the Big Bang is 0 (zero) mass and energy is old, and has been discarded for better theories.

That means for every gram of matter there is a gram of antimatter to offset it. When the two combine they go back to 0. Matter falls into antimatter and vice versa and they cancel each other out.

Except that's not exactly right. Matter and antimatter annihilate, true, but they produce energy as the product of that annihilation. So it's not exactly a zero-sum-game as you seem to think. You may be getting confused by vacuum flux (a real phenomenon that has been experimentally observed), in which pairs of virtual particles and anti-particles are spontaneously created in a vacuum, only to disappear without a trace when they collide again. In that case, you end up with nothing (unless you're talking about a region of space arbitrarily close to the event horizon of a black hole -- that's how Hawking radiation works).

Now that the universe is mature you don't see it anymore since all the matter and antimatter are supposedly far enough away from each other that they don't annihilate anymore. Or at least often.

Try "never." The current standard model in cosmology posits that matter and antimatter were created in nearly equal quantities which condensed out of the energy of the Big Bang. The resultant mass reacted with itself, and the energy produced by these annihilations generated the next wave of particle creation. Eventually, a very slight bias in the production of matter vs. antimatter led to the overwhelming dominance of "normal" baryonic matter in the visible universe.

The idea that there are vast pockets of antimatter out there in the universe has been generally discarded. As for why there was a bias toward "normal" matter and against antimatter, I don't think that has ever been adequately explained, although there are several competing theories. It's interesting to note that in quantum mechanics, you can model antimatter interactions as a sort of time-reversal of matter interactions -- leading to the bizarre notion that antimatter is just normal matter that's "backwards" in time. Perhaps entropy provided enough of a "time arrow" to force a bias in the early universe's composition. (Or, as I sometimes muse, there might be some as-yet-unknown force that is responsible for breaking symmetry in time, and entropy as we understand it is just a product of this force.)

The "antimatter is just matter backwards in time" concept was kind of a shocker to me, taking quantum mechanics classes as a college undergrad. I'd been introduced to the concept by a story or novella that was published in Analog, and had dismissed the idea as hokey... and then one day, I cracked open one of my textbooks and saw a weird little diagram, and asked why there was an electron moving backwards in the time dimension, to which the professor responded, "That's a positron."

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