I am partial to gamma-ray bursts.
First, they are simply too cool: the titanic explosion of a supermassive star triggers twin beams of gamma rays that contain as much energy as the Sun will generate over its entire lifetime. These cosmic blowtorches chew their way out of the exploding star and tear across the Universe, and, in the first few thousands light years, destroy anything they touch. Eventually, weakened by distance, we see them only as a sudden flash of gamma rays (extremely high-energy light) which fades rapidly, never to be repeated.
Second, I worked for several years on the education program for the Swift satellite, which targeted GRBs. For quite some time I kept track of every burst seen, and how they behaved.
GRB 070125 — a burst seen on January 25, 2007 — was unusual. That was obvious even when I wrote about it at the time: it was intense, long-duration, but had no features in its spectrum. Usually, a spectrum taken of a burst shows some features that allow astronomers to get a distance, or determine various other characteristics of the burst. But this one was peculiarly empty of such things. Eventually, a faint feature was found that allowed a distance determination: at least 9.4 billion light years, about average for GRBs, but still a mind-numbing distance.
But the big surprise was to follow. Observations made after the glow of the burst had faded revealed no underlying galaxy! This is extremely weird. Massive stars which trigger GRB explosions die when they are still young, having consumed their fuel at a furious rate. Therefore we expect to see these types of bursts happening not only in galaxies, but specifically in locations in galaxies where stars are being born.
But GRB 070125 is an orphan. Deep images of the region where it went off yield no galaxy. There are two somewhat nearby, but they are at least 80,000 and 150,000 light years way, far too distant for either to be the host galaxy.
Cool! A mystery!
Astronomers speculate that it’s possible that the two galaxies are interacting, colliding. When that happens, long streamers of stars and gas get drawn out of the galaxies, and stars do tend to form there. If this is what happened, then GRB 070125 isn’t an orphan, it was just born in an exotic locale; if so the "tidal stream", as it’s called, is too faint to be seen in the images. Even deeper images are being planned to see if any tendril of stellar stuff can be seen. If so, then the mystery is solved. If not, well, then, GRBs have a history of being odd, of throwing monkey wrenches into our ideas, and of revolutionizing the way astronomers perceive the Universe.
In that way, at least, GRB 070125 is fairly run-of-the-mill. But that’s only because of the extraordinary company it keeps.
Oh, and if such things concern you, don’t panic: the odds of a GRB going off in our Galaxy and damaging the Earth are extremely remote. I’ll be talking about this quite a bit more on the blog as the time of my book publishing approaches. I have a whole chapter on GRBs; the damage they can do when nearby is terrifying, but happily for us there are no progenitors lurking nearby. This is one cosmic danger that we’re relatively safe from.
December 18th, 2007 at 5:53 pm
Could it have been a coalescing neutron star binary? Since it would take some time for the orbit to decay due to gravitational radiation, such a system could travel through space for quite a long time, perhaps long enough to get a long way from its host galaxy.
December 18th, 2007 at 6:36 pm
I understand that the amount of energy in GRBs are incredibly powerful, but reading your article made me think: Knowing that GRBs are that powerful and that they produce energy in the gamma-ray spectrum, and take into account that they’re moving away from us (aren’t most objects moving away from us?), and since things moving away from us are red-shifted in the spectrum, just how high up in the spectrum do these things emit energy? Is there an upper limit for the EM spectrum? (If there is, I’m sure Max Planck’s name is involved.)
December 18th, 2007 at 8:21 pm
Yup, Warp drive!
December 18th, 2007 at 8:24 pm
I do have to agree GRBs are quite an interesting topic and a very new topic at that. If you worked on the SWIFT satellite I was wondering when that went into orbit, also do you happen to know what percent of the GRBs that are aimed in our direction SWIFT actually catches?
The Fool
newfrontierblog.blogspot.com
December 18th, 2007 at 9:00 pm
Re: extremely remote chance….
I thought Eta Carinae (at 100+ solar masses and 7.5 kLY) was a good candidate for a GRB in our neighbourhood?
Luckily, we don’t appear to be on axis.
December 18th, 2007 at 9:11 pm
I was also going to as about Eta Carinae? Also, here is a question: If one of these GRB’s happened within “Striking Distance” what would the consequences be? Would the burst just affect the side of the planet facing the GRB, or would it affect the whole planet? In other words, what exactly would happen? Sorry if that seems like a dumb question.
December 18th, 2007 at 9:55 pm
Very interesting, i’m not really informed about this topic, but could it be some sort of gravitational lensing, maybe the galaxy is hiding behind… something? is this possible mr. BA?
December 19th, 2007 at 2:51 am
Good thought-provoking and informative article. Good responses - all with astronomy as the topic. Now, let’s hear from creationists as to how they explain GRB’s. Actually, examination of extremely rare phenomena requires a special mix of ingenuity and patience, which could well be a topic for a future article.
December 19th, 2007 at 3:56 am
GRB’s are the farts of God. Well, The Almighty does get gas too.
December 19th, 2007 at 4:02 am
I’m a complete neophyte when it comes to science but the lack of spectrum in this gamma ray burst seems very strange as well.
December 19th, 2007 at 4:45 am
Hurry up and get that book published, Phil. The more you talk about cool stuff like this the more I’m having trouble waiting!
December 19th, 2007 at 5:09 am
To Tony: If it was gravitational lensing, wouldn’t that imply that there was a nearby massive object? There clearly is no such object here. Could it be elusive Dark Matter playing tricks on us?
December 19th, 2007 at 6:49 am
I forget which cable channel it was on, but GRBs are noted as one of the many things from space that will kill us all sooner or later.
December 19th, 2007 at 8:07 am
I read New Scientist’s article on this first: “It may have been the death cry of a star that was born from debris strewn out of a past galactic dustup”.
I saw “death”. I saw “star”. I saw “death star”. Mystery solved.
December 19th, 2007 at 8:11 am
By any chance, could those galaxies shown be millions of lightyears distance, in lieu of thousands? They seem mighty close to be so small, and with a “forground” galaxy, which must be closer still. Seems odd, though we have a lot of dwarf galaxies buzzing about.
December 19th, 2007 at 8:16 am
Again, does the high z-value for these things mean they happened in the early universe but don’t happen any more?
I note the obligatory anti-theist posts by the usual gang of idiots. It seems there isn’t a topic in astronomy where they can’t find some way to say something nasty about creationists or just theists in general. I think I’ll try to stop responding to most of these — there are so many — and will just concentrate on the really outrageous ones.
December 19th, 2007 at 9:25 am
A couple of BAUTers cleared-up my question above. The distances shown are not the distance from us, but distances between the GRB and neighboring galaxies. This is amazaing resolution since the angular distance to the GRB’s nearest galaxy is < 2 arcseconds. The 10 meter Keck is a heck of a scope!
December 19th, 2007 at 9:44 am
“Eventually, a faint feature was found that allowed a distance determination: at least 9.4 billion light years, about average for GRBs, but still a mind-numbing distance.”
“There are two somewhat nearby, but they are at least 80,000 and 150,000 light years way, far too distant for either to be the host galaxy.”
Shouldn’t that be far too close?
Also, those galaxies already don’t appear very bright. If the host galaxy is really 100,000 times farther away, is it possible the Keck telescope simply failed to detect it?
December 19th, 2007 at 11:00 am
I went to the NASA site to find out why the bursts look as though they’re coming from narrow streams opposite each other from the sphere of the collapsar/hypernova star, but there’s nothing about the shape of the event. I am I in error about the shape? Does the event involve the entire star?
December 19th, 2007 at 1:13 pm
Oh, thank goodness! Gamma ray bursts. Phew!
I thought it was going to be a tragic tale of overfed orphans with some vague astronomical connection.
December 20th, 2007 at 8:24 am
# Quiet_Desperationon 19 Dec 2007 at 1:13 pm wrote :
“Oh, thank goodness! Gamma ray bursts. Phew!
I thought it was going to be a tragic tale of overfed orphans with some vague astronomical connection.”
OVER-fed orphans? Overfed?
I can just see this! (With apologies to Charles Dickens & Oliver Twist.)
“Please sir can I have some more … & more .. & more .. & more & … Ooop! Blerggh!”
POP!
“Right-o orphans get the mops!”
December 20th, 2007 at 3:01 pm
One of the more interesting, and somewhat depressing, answers to the Fermi paradox is that a galaxy won’t start seeing advanced civilizations until star formation has slowed enough such that the average amount of time it takes for an advanced civilization to evolve begins to outpace the average time between your run of the mill planetary star system is bathed in lethal radiation from nearby GRBs, and that this is the era our galaxy is in.
There’s a paper on it here! http://arxiv.org/abs/astro-ph/9901322
December 21st, 2007 at 10:34 am
Singe writes:
[[One of the more interesting, and somewhat depressing, answers to the Fermi paradox is that a galaxy won’t start seeing advanced civilizations until star formation has slowed enough such that the average amount of time it takes for an advanced civilization to evolve begins to outpace the average time between your run of the mill planetary star system is bathed in lethal radiation from nearby GRBs, and that this is the era our galaxy is in.]]
I think GRBs may have all taken place in an earlier era of universal history. The event this thread is about took place 9.4 billion years ago, did it not? I don’t think there are any nearby GRBs. Dr. Plait is probably more up on this than I am and can correct me if I’m wrong.