Did "Dark Matter" Create the First Stars?

Max Planck Society ^ | 15 March 2006 | Staff (press release)

[PatrickHenry]

Dark matter could be "sterile" neutrinos, whose decay led to the formation of stars in the early universe
Dark matter may have played a major role in creating stars at the very beginnings of the universe. If that is the case, however, the dark matter must consist of particles called "sterile neutrinos". Peter Biermann of the Max Planck Institute for Radio Astronomy in Bonn, and Alexander Kusenko, of the University of California, Los Angeles, have shown that when sterile neutrinos decay, it speeds up the creation of molecular hydrogen. This process could have helped light up the first stars only some 20 to 100 million years after the big bang. This first generation of stars then ionised the gas surrounding them, some 150 to 400 million years after the big bang. All of this provides a simple explanation to some rather puzzling observations concerning dark matter, neutron stars, and antimatter (Physical Review Letters, March 10, 2006).

Scientists discovered that neutrinos have mass through neutrino oscillation experiments. This led to the postulation that "sterile" neutrinos exist - also known as right-handed neutrinos. They do not participate in weak interactions directly, but do interact through their mixing with ordinary neutrinos. The total number of sterile neutrinos in the universe is unclear. If a sterile neutrino only has a mass of a few kiloelectronvolts (1 keV is a millionth of the mass of a hydrogen atom), that would explain the huge, missing mass in the universe, sometimes called "dark matter". Astrophysical observations support the view that dark matter is likely to consist of these sterile neutrinos.

Biermann and Kusenko’s theory sheds light on a number of still unexplained astronomical puzzles. First of all, during the big bang, the mass of neutrinos created in the Big Bang would equal what is needed to account for dark matter. Second, these particles could be the solution to the long-standing problem of why pulsars move so fast.

Pulsars are neutron stars rotating at a very high velocity. They are created in supernova explosions and normally are ejected in one direction. The explosion gives them a "push", like a rocket engine. Pulsars can have velocities of hundreds of kilometres per second - or sometimes even thousands. The origin of these velocities remains unknown, but the emission of sterile neutrinos would explain the pulsar kicks.

The Guitar Nebula (image) contains a very fast pulsar. If dark matter is made of particles which reionized the universe - as Biermann and Kusenko suggest - the pulsar’s motion could have created this cosmic guitar.

Head of the "guitar nebula". The formation contains a fast moving pulsar followed by a tail of gas. Biermann and Kusenko’s postulations about dark matter could explain puzzlingly high pulsar velocities, which lead to such cone-shaped features. Images are from the Planetary Camera aboard the Hubble Space Telescope in 1994 (left) and 2001 (right).
Image: Hubble Space Telescope (NASA/ESA), Shami Shatterjee 200

Third, sterile neutrinos can help explain the absence of antimatter in the universe. In the early universe, sterile neutrinos could have "stolen" what is called the "lepton number" from plasma. At a later time, the lack of lepton number was converted to a non-zero baryon number. The resulting asymmetry between baryons (like protons) and antibaryons (like antiprotons) could be the reason why the universe has no antimatter.

"The formation of central galactic black holes, as well as structure on subgalactic scales, favours sterile neutrinos to account for dark matter. The consensus of several indirect pieces of evidence leads one to believe that the long sought-after dark-matter particle may, indeed, be a sterile neutrino", says Peter Biermann

[Contact information and related links omitted.]

[PatrickHenry]

Gentle reminder: Now hear this: No personal attacks (title of thread posted 15 March 2006 by Jim Robinson).

[PatrickHenry]

SciencePing

An elite subset of the Evolution list. See the list's explanation at my freeper homepage. Then FReepmail to be added or dropped.

[Andy from Beaverton]

I thought this was the bowling pin nebula?

[MAD-AS-HELL]

Get your facts straight, AL GORE created the first stars. God knows he spouts a lot of hot gas.

[King Prout]

looks like the Lava-Lamp Nebula to me

[robertpaulsen]

"Dark matter may have played a major role in creating stars ..."

Dark Matter? No, I think it was Dark Helmet.

[Moonman62]

Nice find PH. Sterile neutrinos sound like they could be the missing piece to the puzzle.

[ketelone]

Very interesting.

[VadeRetro]

"sterile" neutrinos

Sterile AND neutered AND tiny, but still somehow important to the history of the universe. There's hope for Kent Hovind's brain.

[aMorePerfectUnion]

perhaps a better question is, "Did God make the stars out of dark matter?"

[robertpaulsen]

I thought it was the Michelob nebula.

[longshadow]

Can you guys elaborate on this "sterile neutrino" stuff? I've never run into the term before. Does this mean that there are more than three types of neutrino? From the article:

"This led to the postulation that "sterile" neutrinos exist - also known as right-handed neutrinos. They do not participate in weak interactions directly, but do interact through their mixing with ordinary neutrinos."

[Quark2005]

Scientists discovered that neutrinos have mass through neutrino oscillation experiments. This led to the postulation that "sterile" neutrinos exist - also known as right-handed neutrinos.

More than mere postulation. If neutrinos do indeed have mass (and the evidence points to yes) then right-handed neutrinos must exist according to relativity & quantum field theory. I don't know whether this was inappropriate choice of wording or if "sterile" neutrinos are actually something different than mere right-handed neutrinos (I've never heard this term before).

Very interesting, though.

[trillabodilla]

"Did Dark Matter Create the First Stars?"

No, God did.

[Getready]

Interesting post...still so many other questions out there,
like how do neutrinos "steal" "lepton numbers", and why?
I mean how is a lepton number useful to anything? What is
a better metaphor than "stealing"...using that term implies
some sort of qualitative aspect of the neutrinos behaviour..
isn't "taking" a better description?...
And where do right hand neutrinos come from?

[ketelone]

And what are they, and how did they end up becoming the formative matter of the universe, and why dont we see any on earth, and will we ever be able to travel faster than light, and so forth.

These questions may never be answered.

My feeling is, that the enormous distances of space will end up not mattering at all, if we can somehow manage to become immortal.

D = SxT

Ie: Either we try an get there much faster. Or we give our selves an infinite amount of time. Then distance just doesnt matter any more.

[Alamo-Girl]

Thanks for the ping!

[orionblamblam]

Odin didit!

[beezdotcom]

And, isn't the article using some improper shorthand when they equate "sterile neutrinos" to "right-handed neutrinos", since "sterile neutrinos" might also be "left-handed antineutrinos"? Or am I forgetting something (quite likely)?

[Quark2005]

And, isn't the article using some improper shorthand when they equate "sterile neutrinos" to "right-handed neutrinos"...

I was wondering the same thing (#13).