Note: due to the holidays and other personal reasons, this may be my last blog entry until next week. I’ll post more if I can, but no promises.
One year ago Sunday, the Swift satellite roared to orbit on top of an Delta rocket. Over the next few weeks, scientists and engineers gingerly activated the complex equipment onboard Swift that would allow it to fulfill its mission: to detect and observe gamma-ray bursts, flashes of high-energy light which appear to signal the births of black holes.
These bursts were one of the leading mysteries in astronomy for the past few decades. They would last as long as a few minutes, or as short as a few milliseconds. They would flash out their gamma rays, and sometimes — rarely — leave an afterglow in visible light. Gamma rays are notoriously difficult to trace; the best anyone could do was tell you kinda sorta where the gamma rays had come from, but it was difficult to get a good location for them on the sky. Without that, it was impossible to know what caused the bursts.
This was a real problem! It was difficult to imagine what could be causing these odd bursts. It was known they were happening very far away, billions of light years away. Earlier satellites had determined that. But the energetics of the explosions are truly awesome. They release as much energy in a few seconds as the Sun will over its entire lifetime. More.
But what physics lies at their heart? What could cause such vast explosions?
Swift, it was hoped, would solve that problem. It had the best hardware ever made for locating gamma-ray bursts. Once it pinned down the location looking at gamma rays, it would rapidly — hence its name — point its X-ray and Ultraviolet/Optical Telescopes at it, and nail the location very precisely. The coordinates were then to be beamed to the ground so that telescopes on Earth could follow-up.
When Swift launched, we had a lot of hopes riding along with it, hopes that this maddening mystery of GRBs would finally be cracked.
That was a year (and a day) ago now, and Swift has performed beautifully. It has seen dozens of bursts (roughly two per week, on average) and seen afterglows on quite a few. It has seen the most distant burst detected at a whopping 12.8 billion light years away. It has seen short and long bursts, bursts near and far, faint and bright (it caught a burst just last week that may have had the second brightest afterglow ever seen). The list goes on and on. You can even keep up with the latest bursts seen by Swift (and other satellites) on a website that updates this information in real-time: http://grb.sonoma.edu.
Swift has done so well that Popular Science magazine chose it as the Best of What’s New 2005, an award it richly deserves.
Swift is one of several satellites that provide funding to my group at Sonoma State University, and I’m proud to be able to talk about it in schools, at teacher conferences, in magazines, and of course on my blog. Swift has at least one more year in its mission, unless NASA decides to extend its mission longer. I think that’s a pretty good bet.
Happy anniversary, Swift.
November 20th, 2005 at 8:10 pm
Happy Anniverary Swift
Happy Holidays BA
Clear skies to all
November 21st, 2005 at 10:25 am
And, keep in mind, Swift is one of the few satellites with it’s own theme song, which makes it that much cooler!
http://swift.sonoma.edu/resources/multimedia/song/
November 21st, 2005 at 10:28 am
Slightly off-topic I know, but I thought I’d mention that today is the hundredth anniversary of Einstein’s Special Theory of Relativity! Happy birthday STR!
November 21st, 2005 at 10:59 am
Will miss your blogs, but Happy Christmas and a Merry New Year.
To Jeffrey:
Maybe it’s just my taste of music…. But science and music doesn’t really mix that well.
Maybe these guys (link below) could be convinced to spruce it up a bit.
http://www.beatallica.org/2004ep/Beatallica%20-%2006%20-%20Hey%20Dude.MP3
November 21st, 2005 at 1:56 pm
[...] note from Michelle: if The Planets is your cup of intergalactic tea, check out Phil Plait’s Bad Astronomy Blog. Published in: [...]
November 21st, 2005 at 3:53 pm
I assume that although Swift is noticing a lot more of these events, it isn’t necessarily noticing all of them.
On that basis, does the frequency of these events give any clue as to their origin? My thinking is that the more frequent the events, the more likely they are to be stellar in origin as opposed to galactic.
What’s the current thinking on the cause of these events?
November 21st, 2005 at 4:56 pm
Thomas Siefert, he said week, not month. That means Thanksgiving, not christmas (yet).
November 21st, 2005 at 7:59 pm
If I remember correctly, Swift’s field of view is approximately 1/6 of the sky. With that being said, on occsasion, it has detected gamma rays that come from its backside, pass through the spacecraft, and set off the detectors for very bright events. It can’t slew to these as it can’t pinpoint them.
Actually, Peter B, I think the opposite is true. The more frequent the events occur, the more likely they are to be extragalactic in origin. Our solar system is a relatively small volume, therefore I would expect fewer events to occur in a small volume. GRB’s occur at cosmological distances which cover a HUGE volume. Therefore, I would expect more events to come from a larger volume.
There is no definite proof of a nearby GRB. At the 2004 AAS meeting, however, a paper was presented arguing that WB49, a nearby Supernova remnant, may have been a GRB. They argued that they saw a jet with the correct abdunanes of elements in the SNR, if I remember correctly. Last I heard, it was still a fairly controversial claim.
I was supposed to be there for the Swift launch and then it got delayed
Still, I did get an amazingly awesome tour of the Cape, which included taking the elevator to the top of the Delta II rocket that launched Swift and getting up close and personal with it!
Go Swift!
Rob
November 21st, 2005 at 11:09 pm
Hale_bopp
I think you’re misreading what I was asking. When I said “stellar” I meant events happening to stars, as opposed to “galactic” events happening to galaxies.
In other words, do we have a handle on what GRBs are yet? Is a GRB something which happens to a star, or is it something which happens to a galaxy?
November 21st, 2005 at 11:36 pm
Recently published evidence reports that GRBs most likely occur during the formation of black holes. Whether they are stellar or galactic in origin doesn’t make a difference. The overall energy released when the intrinsic matter of such massive stars collapse, sends GRB’s jetting in our direction. Further, it has also become apparent, that follow up x-rays from those same bursts may occur when the newly formed black holes, quickly swallow part of the outer layer of the outwordly expanding shell of gas (of course most of it is still projected away from the central singularity, forming an expanding supernova bubble).
November 22nd, 2005 at 12:02 am
Phil,
Happy Thanksgiving to you and your family!
November 22nd, 2005 at 7:13 am
To Irishman:
He did say ‘week’ Me so stupid!
Guess the word holiday sidetracked me since it’s not celebrated here where I am and the closest one i could think of was christmas.
See how easy we can miss-communicate because of cultural differences.
Well, Happy Thanksgiving and good luck with sacrificing the turkey (or is that christmas? or both?).
November 22nd, 2005 at 9:40 am
Yes, Peter B, I thought you were referring to where they occur. Sorry, I wasn’t clear on that.
Anyway, now that I understand the question, I can have a go at it
Given the fact that GRBs are short lived events, they must take place on small scales. Ther period of variability of an object sets a limit on its size and GRBs miust come from a volume, at most, a few light minutes across, frequently less than that. This size pretty much rules out anything objects of roughly stellar size or smaller.
There a two classes of GRBs, long and short. Long GRBs and thought to be hypernova, souped up supernova. GRB 030329 is widely regraded as a smoking gun, linking a long GRB to a hypernova.
Short GRBs must take place in much smaller volume. They are thought to be the merger of two neutron stars or neutron star/black hole merger. This will be much more difficult to nail down for sure, but the early data from Swift does support the merger of two compact objects.
Of course, now there are two recent Swift triggers which may be extragalactic magnetar eruptions (also known as soft gamma repeaters or SGRs). SGRs from nearby galaxies could account for some of the shorts bursts (estimates about 10%-20%).
So there are still a lot of questions to be answered and that is why we all want Swift to have its mission extended
Rob
November 22nd, 2005 at 11:24 am
Thomas, yes, turkey is often (but not always) had for both holidays. Ham is also a frequent victim.
Peter B, I’m a bit confused. Can you give an example of an event that is galactic in origin, i.e. from a galaxy as a whole rather than from stars within the galaxy? Otherwise, I’m a bit strained to understand your question. I would think that things we pinpoint to other galaxies are only due to the scale factor that we cannot pinpoint any finer detail, i.e. the star within that galaxy. Thus the easy misinterpretation of your question to mean local vs. distant. Everything* is stellar – just whether we can see the star or only the galaxy that surrounds it.
*For a given definition of “everything”.
November 22nd, 2005 at 5:22 pm
G’day Irishman
I suppose the sort of galactic event I had in mind was a black hole at the core of a galaxy having a severe case of indigestion.
The basis of my question is this: there are many more stars than galaxies. So if these events are being recorded often, they’re either happening rarely among lots of stars, or very often among fewer galaxies.
Does that make sense?
November 22nd, 2005 at 10:03 pm
Yes, I see what you are getting at Peter B. There massive black holes at the centers of galaxies and these can flare. Their period of variability is generally on the order of hours (8 hours is the shortest verified one) to days whereas GRBs are milliseconds to minutes. Their spectra are also substantially different. Additionally, GRBs do not repeat and flares from active galaxies can and do repeat.
GLAST, the Gamma Ray Lare Area Space Telescope (another one of Phil’s education projects) will study AGN flares and it will carry a burst monitor to look for additional gamma ray bursts.
There is a short article in the January 2006 Sky and Telescope (I just got it today) about Swift. They outline pretty much what I said earlier…long bursts are hypernova, short bursts are the merger of two compact objects (neutron star-neutron star or neutron star-black hole).
Rob
November 24th, 2005 at 12:23 am
Hey, i know this is completely off topic, but i was wondering if any of you could tell me what a decent starting telescope in the $500 range would be, eg. type, size etc.
Thanks a lot!
November 24th, 2005 at 12:53 pm
Um,
”Swift is one of several satellites that provide funding to my group at Sonoma State University”
is that sentence backward or am I missing something fundamental?
J
November 28th, 2005 at 1:27 pm
James, I think you’re missing something fundamental.
The way I read the linked description of the Sonoma State University page, NASA formed their group at SSU to develop educational and outreach materials and to perform public outreach. These activities need funding (by NASA), and that money comes from specific projects that they are supporting. The funding comes from line items or general funds within those project budgets, so the projects pay SSU to perform the outreach. In that light, I think you can see why it wouldn’t make sense for SSU to paying for the privilege of working for Swift.
http://epo.sonoma.edu/
antipodean, you might look here:
http://www.badastronomy.com/bitesize/scopefaq.html
Also, a better place to ask this question is on the BAUT forum. There you can start your own topics of discussion.
http://www.bautforum.com/
November 28th, 2005 at 11:31 pm
soz, won’t do it again
November 28th, 2005 at 11:34 pm
thanks for the help though
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