Skip to comments.Quark soup may cause cosmic flashes
Posted on 02/24/2005 12:17:45 AM PST by LibWhacker
Gamma-ray bursts could be the signature of ultradense stars.
This X-ray image shows the 3C58
pulsar, the remnant of a supernova
noted on Earth in AD 1181, which
astronomers suspect may be a quark
star. It lies about 10,000 light
years from Earth.
© NASA/SAO/CXC/P.Slane et al.
Intense flashes of gamma rays in far-off galaxies might be produced by a bizarre kind of star, consisting of phenomenally dense material in which the particles that make up atomic nuclei have fallen apart.
Two astrophysicists have proposed that gamma-ray (gamma-ray) bursts, whose origins have foxed astronomers for decades, might be the signatures of elusive 'quark stars'. Scientists have speculated that these stars might exist, but have never seen convincing evidence for them.
Bohdan Paczyn acuteski of Princeton University in New Jersey admits that the idea that he and Pawel Haensel of the Copernicus Astronomical Centre in Warsaw, Poland, have put forward is still theoretical, and must be tested with more g-ray observations.
But within days of posting their paper on the arXiv preprint server1, the researchers were given good reason to believe that they are on to something. Davide Lazzati of the University of Colorado at Boulder contacted Paczyn acuteski to say that the quark-star hypothesis might explain some puzzling observations made by the Burst and Transient Source Experiment on NASA's Compton Gamma-Ray Observatory, which was launched in 1991.
Lazzati noticed that several of the g-ray bursts seemed to be preceded, a few seconds or minutes earlier, by much weaker pulses of gamma-rays2. "That was a puzzle," says Paczyn acuteski. But an explanation for these precursory flashes "comes naturally out of our model", he says. "It's very exciting."
Astronomers generally believe that g-ray bursts are produced by supernovae: stars that have run low on fuel and do not emit enough energy to prevent them from collapsing under their own gravity.
The collapse heats up the star and generates a 'rebound', in which the star's outer layers get blown off in a massive explosion, while the inner core collapses further into a superdense object called a neutron star. These stars are made entirely of neutrons, the electrically neutral particles in atomic nuclei. They measure just a few miles across and are so dense that a teaspoonful of neutron-star matter weighs about a billion tonnes.
The g-ray bursts seem to be associated with a certain type of supernovae, called type Ic, in which the parent stars have already become quite compact. The g-ray flashes are produced as the supernovae throw out jets of material that move at almost the speed of light. But although only a few have so far been spotted, not all type-Ic supernovae generate these bursts.
Why should the supernovae differ? Paczyn acuteski and Haensel say that the difference could depend on whether the explosion produces a neutron star or whether this superdense core contracts even more, bursting open the neutrons themselves to create a soup of quarks, the particles from which they are made.
The surface of a quark star would act as a kind of filter that stops particles called baryons escaping from the star, says Paczyn acuteski. Baryons are the components of nuclei: protons and neutrons. "The surface of a quark star is a one-way street for baryons," he says.
This 'membrane' could account for the ultrafast jets squirted out of the supernova, because it would be permeable only to non-baryon particles, such as photons and neutrinos, which move at or very close to the speed of light, and would bar the ponderous baryons that slow the jets down.
Crucially, Paczyn acuteski adds, "the transition from a neutron star to a quark star takes time". He and Haensel estimate that it should take a few minutes. That is precisely the kind of delay between the weak precursor flashes reported by Lazzati, which would appear as the neutron star is formed, and the main g-ray bursts, which would come slightly later as it turns into a quark star.
Paczyn acuteski says that the first step in testing their idea is to establish whether there are truly two classes of type Ic supernovae: one with bursts and one without. So far, there are only four observations from which to judge. But the g-ray telescope Swift, launched by NASA last November, should be able to gather much better statistics.
Producers of Cosmic Rays.
One of the articles ( keyword magnetar ):
Yes, saw that one, thanks. Weird universe we live in!
Does Campbell's sell that stuff? Will it get you high? :-)
Fallen apart, or squooshed?
Lol, I was wondering about something similar to that; i.e., how much does a can of Campbell's Quark Soup weigh?
Isn't that what McNabb's mother makes for the Eagles?
Does Campbell's sell that stuff? Will it get you high? :-)
No and no, but my wife makes it and I have cosmic flashes every time.
I see you in the morning
Sleeping next to me....
ping - to locate thread
Not a physicist, so I am waiting to be slapped down by someone who is but... I believe that quarks are not composed of strings according to string theory, but rather that quarks ARE strings. That is, the various quark flavors are different vibrational modes of a string. Electrons, neutrinos, and other leptons would be other vibrational modes of the string.
This is interesting. Ping the list???
Wouldn't a Quark Star be an actor that was in the show 'Quark'?
A very funny sitcom about an interstellar garbage scow.
Arrrggghhh. This is interesting, but not earth-shaking. We already have a big bang thread going this morning, and it drives everyone crazy to have multiple threads going. I'm gonna wait before pinging the list.
An argument for a Science Forum.
And for some of us it's just a short putt.
With keyword searches, you can find all the science threads you want. My personal preference is to keep these theads where they are.
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