If you’re a fan of over-the-top ridiculously huge violent explosions, then you won’t do any better than gamma-ray bursts. With apologies to Douglas Adams and Eccentrica Gallumbits, GRBs are the Universe’s largest bangs since The Big One. When they were first discovered, during the Cold War, it was unclear what caused them. There were more theories than there were observations of them! Now we’ve observed hundreds of these things, and we’ve learned quite a bit about them, like a) every one of them is different, 2) they have lots of different sources, and γ) even after five decades they can still surprise us.
Last year on Christmas, the light from a gamma-ray burst reached Earth and was detected by NASA’s orbiting Swift satellite. Designated GRB 101225A, it was weird right off the bat: it lasted a staggering half hour, when most GRBs are over within seconds, or a few minutes at most. Followup observations came pouring in from telescopes on and above the Earth, and the next weird thing was found: the fading glow from the burst seemed to be coming from good old-fashioned heat: some type of material heated to unbelievable temperatures. Usually, the afterglow is dominated by other forces like rapidly moving super-intense magnetic fields that accelerate gigatons of subatomic particles to huge speeds, but in this case it looked like a regular-old explosion.
Both of these things are pretty dang weird. So what could have caused this burst?
Normally, we think GRBs are the birth cries of black holes. When a giant star explodes, or two tiny but ultra-dense neutrons stars merge, they can form a black hole and send vast amounts of gamma rays (super high-energy light) sleeting out into the Universe. In this case, though, something different happened, and two ideas of what was behind it are emerging…. but both involve neutron stars. And I’m not sure which idea is cooler.
Is this the most distant object ever seen?
[Click to deathfromtheskiesenate.]
That is GRB 090429B, a gamma-ray burst (or just GRB to those who want to sound nerdcool), the catastrophic and extremely violent detonation of a massive star. Think of it as a super-supernova, the death throes of a star that lived a short, hot, turbulent life. I wrote about them extensively in my book "Death from the Skies!", or you can get the details about how they form and why they’re so awesome in an earlier post.
Its distance is estimated to be a whopping 13.14 billion light years. If this holds up, it may be the single most distant object ever seen by humans.
But is this really a record-breaker? And why aren’t we sure? OK, this takes a wee bit o’ explaining, but I think you’ll like it. After all, it’s an explosion so big it’ll crush your mind into dust.
[UPDATE: Due to a typo in my math notes early on, I incorrectly said the distance to this burst was 13.4 billion light years. D'oh! I have corrected all the numbers below, and I apologize for the error.]
Boom! goes the dynamite
The important thing here is that they are so bright — emitting more light in a few seconds than the Sun will over its entire lifetime — that they can be seen for tremendous distances. In fact, they can be detected from clear across the Universe, which is where GRB 090429B comes in.
It was first seen on April 29, 2009 (hence the name 090429B — it was actually the second GRB seen that day) by Swift, NASA’s satellite specifically designed to detect GRBs and rapidly transmit their locations to telescopes on the ground. GRBs fade very quickly, in minutes or even seconds, so rapid response is critical. In this case, observations by ground-based telescopes quickly revealed this was an unusual burst. Within hours astronomers began to suspect it was vastly distant. Estimates started putting it at greater than 13 billion light years away, almost as far as an object can be in the distant Universe.
Far, far away
Frustratingly, clouds prevented the monster Gemini 8-meter telescope from getting a spectrum of the burst, which would have nailed down its distance. Without that, the distance can only be estimated. However, several factors indicate it really is at this extreme distance:
Last weekend I was in NYC attending the Northeast Conference on Science and Skepticism, aka NECSS. It was a lot of fun, as I kinda figured it would be. Skeptic conferences usually are! And of course it was a chance to catch up with a lot of old friends.
Attendees are writing their opinions of the meeting all over the place (like here, here, and here for starters). I’ll spare you the recap, which would boil down to how awesome my talk was, and cut to the chase which is to thank Michael Feldman from the New York City Skeptics, and all the folks from the New England Skeptical Society for inviting me and throwing such a fab conference.
I’d be remiss, though, if I didn’t include this little bit of funnery. Skeptical singer songwriter and BA friend George Hrab was at NECSS. On Geo’s last album, "Trebuchet", he wrote a tune called "Death from the Skies" — based on the brilliant book of the same name. He plays the funky beat, and I read statistics of getting killed by various astronomical events. We performed this song live both at Paddy Reilly’s, a bar where Geo had a gig, and to close out the ceremonies.
Here’s the recording of the latter, which is pretty laid back considering how many octillions of Joules of energy I’m talking about:
And what the heck, here we are at the somewhat more rambunctious bar the night before:
See? If you go to skeptic meetings you can experience stuff like this live. It’s way too much fun.
There are photos of NECSS popping up all over the place (search Flickr), including for example a nice set by Bruce Press. I also like this shot of Geo and me taken by Brian Engler. Apparently I had just stubbed my toe.
NECSS really is a terrific event. I hope to see you all there next year!