# Talk:Gamma-ray burst/Archive 1

What is a "pair-instability supernova" ?

Paragraph 5 of Discovery is confusing.

What the hell is a CCD? and that second line "and mounted on" Needs to be revised! But otherwise, good job world :) >> A CCD is what digital cameras use to translate light(images) into electronic signals(bytes of information)

Superb article Greg, good to see you here.

Changed some of the information. The hypernova hypothesis is promising, but there is far too much handwaving for anyone to really be satisfied by it: supernova collapses to a black hole, (mumble) (mumble) (magic happens) (mumble) then a beam of gamma ray emerges.

Also, a gamma ray burster at several hundred light years would probably not incinerate the earth. This is a nice undergraduate exam question, but I think the number works out that it needs to be a few light years away to incinerate the planet. This is actually reassuring since we know what the neighorhood is like up to a few light years. Extend the danger zone to a few hundred light years, and then things get scarier.

Roadrunner 04:54, 16 Feb 2004 (UTC)

Bad news is, you don't need to incinerate the planet to exterminate all life...--AstroNomer 09:11, Feb 16, 2004 (UTC)

More recently, gamma ray bursters have been linked to Wolf-Rayet stars. A very readable account was written recently by John Baez in This Week's Finds in Mathematicals Physics (Week 204).
Herbee 00:22, 2004 Apr 4 (UTC)

Hello, By the way, I found a nice afterglow picture of a famous GRB (GRB-990123) at a NASA-site (picture is in the Public Domain): http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/09/image/a

I'm already using it in the german article of this topic ( http://de.wikipedia.org/wiki/Gammablitz ) and I find it quite illustrating. At the moment I'm looking for a free picture showing a "time - energy graph" of a Gamma Ray burst, but wasn't sucessfull so far. Arnomane

What is meant by "GRBs occur twice or three times a day"? Wouldn't the frequency depend on how good the detector is? I mean, if you increased the resolution, wouldn't you be able to detect more GRBs? Arvindn 13:02, 17 Jun 2004 (UTC)

No, you wouldn't. There are 2-3 gamma-ray bursts in the Observable Universe. It is a physical impossibility to detect anything outside the observable Universe as it would take longer than the lifetime of the Universe for the gamma-rays to reach you. So you will never detect more than 2-3 full-blown bursts (although "micro-bursts" might be too faint to be detected -- these usually come from stars and are quite different). Rnt20 18:10, 7 October 2005 (UTC)
I think you have a point, so I changed it to "detected 2 or 3 a day". In any case, what is important here is the sensitivity, not the resolution.--AstroNomer 09:16, Jun 18, 2004 (UTC)

## X-Ray burster

I went to a lecture by Shri Kulkarni a week ago and he debunked the theory that X-Ray Flashes are actually GRBs seen from the side. Does anybody have some info on this theory? Should something go to the page? Gadykozma 11:27, 20 Oct 2004 (UTC)

## Bursters vs. burst

I think this site should be moved to "Gamma ray burst" instead of the current "bursters" google gets like twenty times the hits for the former as opposed to the latter terminology and I think "bursters" is an outdated term.....--Deglr6328 08:04, 24 Nov 2004 (UTC)

I agree with Deglr6328! I actually saw the name "burster" in WP for the first time, never in any literature. Awolf002 14:50, 24 Nov 2004 (UTC)

• Changed it...--Deglr6328 08:48, 25 Nov 2004 (UTC)

## mass extinction

Text is taken nearly verbatum from the NASA website. Stbalbach 16:09, 13 Apr 2005 (UTC)

## New info on CNN.com

Nice article. There was a story on CNN about new finind from the Swift craft that could be integrated as new info

## Colliding Neutron Stars/Back holes Theory

NASA announced on 5th October 2005 that they have solved the 35 year old mystery of the cause of GRBs claiming that they are caused by the collision of two neutron stars or a neutron star and a black hole. You can read the annoucement on the SWIFT website:

http://www.nasa.gov/mission_pages/swift/main/index.html--131.251.0.20 16:01, 7 October 2005 (UTC)

Usual NASA hype / media hype! There are two sorts of bursts, short duration and long duration. The long duration bursts come from Hypernovae (large supernovae with directional jets along the axes) and the short duration bursts come from neutron stars or black holes colliding. A friend of mine did a masters thesis on the colliding neutron star gamma-ray bursts in the 1990s (Bram Venemens -- now doing a postdoc in Cambridge), so I don't see what's so new about them. Rnt20 18:06, 7 October 2005 (UTC)

Well, there is a "slight" difference between explaining the two types in a (theoretical?) paper and actually measuring data matching those predictions. I agree with the "hype" comment, but the Swift data is going to give us new insight once there is sufficient statistics. Awolf002 18:36, 7 October 2005 (UTC)

## Hyperspace

Could this be spacecraft going into hyperspace??--Gbleem 04:40, 26 November 2005 (UTC)

## Correlations...

Was it really the May 5th burst that was thought to have been caused by two neutron stars? If that was the predicted cause, then it should be a short burst, no? And as far as I can tell, the 5 May burst was not short...do you mean the 9 May burst instead?

## Duration of GRBs

The second sentence " They consist of flashes of gamma rays that last from seconds to hours " is not completely correct Short duration GRBs can last few milliseconds. I would suggest to replace it with " They consist of flashes of gamma rays that last from few milliseconds to hours "

## Early theories

The name of the section is a bit misleading; GRBs were found in the 60s and there were various theories about their origin before the Compton Gamma Ray Observatory, which proved them to be very distant (because GRBs occur evenly around the sky). For example, GRBs generated by asteroids falling on the surface of neutron stars was one such theory. Now the section discuss only theories put forward in 1999 or later.--JyriL talk 19:20, 13 May 2006 (UTC)

• The even distribution of GRBs across the sky does not prove they are distant: it could just as likely mean that GRBs are in fact very CLOSE. The only definitive proof of GRBs being distant was the detected redshift from afterglows, in the late 1990s.--Sharkbait784 Talk 19:27, 15 May 2006 (UTC)
Sure, but it was quite clear that the explosions were cosmical.--JyriL talk 19:02, 15 May 2006 (UTC)

No, it was not. It took the BeppoSAX localization, and the subsequent measurement of redshifts, to demonstrate that GRBs were at cosmological distances. The CGRO all-sky distribution could be explained by an extended Galactic population, or even a population of GRBs in the Oort Cloud. —Preceding unsigned comment added by 98.204.109.61 (talk) 02:38, 13 August 2008 (UTC)

## Hypernova

I've removed the hypernova terminology, as GRBs now seem to come from supernovae, judging from the relatively ordinary afterglows they are associated with. Mordecai-Mark Mac Low 17:10, 29 May 2006 (UTC)

That does not sound right to me. GRB's come in multiple distinct classes, and only one of them may most likely be related to "standard supernovae". Please, be cautious with your changes!! Awolf002 17:15, 29 May 2006 (UTC)
Thanks for the prompt response. However, if you actually look at the change, you'll notice that I just changed hypernova to supernova in the appropriate place. Mordecai-Mark Mac Low 17:29, 29 May 2006 (UTC)
I recently had to write a physics paper on GRBs. In my reserch, I found that the sun emits Gamma Rays during solar flares. Solar flares are supposed to peak in 2012, and have some big ones. Could the Sun emit a GRB during a solar flare? Is it any coincidence that, according to the Mayan Callendar, the world ends in 2012? Please respond. Thanks in advance! Da Kat 11:22, 24 November 2006 (UTC)
lolz --Deglr6328 22:22, 24 November 2006 (UTC)
I have a 20 yr mortage, does that answer your question? :-) Maury 22:26, 24 November 2006 (UTC)
While solar flares do often include gamma rays, they're not the same thing as a GRB, particularly as they span the entire spectrum. GRBs are far, far more energetic, and they are not observed inside our own galaxy, much less coming from the sun. Also, the currently theorized mechanisms for GRBs involve very different circumstances than that in our own solar system. So, no, the sun cannot emit a GRB ever, and will not even go supernova at the end of its life. As for the Mayan calendar, unless you can tell us that they knew something we don't, anything that aligns with it is sheer coincidence. According to what we have at Maya calendar, it seems that 2012 is not even necessarily indicated as the end of the world anyway. siafu 08:11, 25 November 2006 (UTC)

## Reorganization

Right now the article proposes two sets of explanations for GRBs -- one older (under "Modern Ideas"), one more modern (in the Introduction). I'm removing the vague older verbiage, reproduced below, and moving the modern explanation out of the intro, into the section "what is a GRB/modern ideas". As that seems like important information, I'm then moving it up above some of the historical development. Mordecai-Mark Mac Low 17:29, 29 May 2006 (UTC)

Data on GRBs is still sketchy and they remain mysterious. Spectra have proven difficult to obtain, and only a few bursts have accurate distance measurements. Although the temporal variations of GRB spectra are varied and show no obvious pattern, the spectral energy distributions (SEDs) can be well described by the following formula, first proposed by D. Band et al. in 1993:
${\displaystyle N(E)={\begin{cases}{E^{\alpha }\exp \left({-{\frac {E}{E_{0}}}}\right)},&{\mbox{if }}E\geq (\alpha -\beta )E_{0}{\mbox{ }}\\{\left[{\left({\alpha -\beta }\right)E_{0}}\right]^{\left({\alpha -\beta }\right)}E^{\beta }\exp \left({\beta -\alpha }\right)},&{\mbox{if }}E<(\alpha -\beta )E_{0}{\mbox{ }}\end{cases}}}$
Where E is the photon energy, ${\displaystyle \alpha }$ and ${\displaystyle \beta }$ are known as spectral indices (with typical values of ${\displaystyle \alpha \sim -1}$ and ${\displaystyle \beta \sim -2}$) and ${\displaystyle (\alpha -\beta )E_{0}}$ is known as the break energy. This model has proved to be very successful in describing the different SEDs of GRBs.
Distance can be measured from the redshift of the GRB. However, gamma ray measurements do not have a distinctive line structure and so a redshift measurement can rarely be obtained from them. Sometimes only distance estimates can be made using absorption lines from the gas along the line of sight to the GRB. Some astrophysicists believe that the rate at which a GRB flickers may provide a useful index of its distance, and might even be a useful standard candle for determining distances to the far reaches of the cosmos.
There is also the puzzle that the burst durations fall into distinct "long" and "short" categories. The long bursts are generally agreed to be associated with collapsars, while the short bursts are thought most likely to be the result of the mergers of pairs of neutron stars, or of a neutron star with a black hole.
Despite the fuzzy data and many questions, astronomers now feel they are closing in on a solution to the mystery, and remain very excited. They are making good use of the tools available for the job. The hypernovae model relies on the energy of the collapse being beamed along the rotation axis of the star, due to the torus of material spiraling into the black hole. Simulations of coalescing neutron stars also provide a very realistic explanation for the short duration bursts.
The astronomers have obtained much more information from the US High Energy Transient Explorer 2 (HETE-2) satellite, launched on 9 October 2000. The first HETE satellite had been launched on 4 November 1996, but it had been trapped in orbit in its payload shroud. Burst hunters were disappointed, but they were able to obtain a replacement. HETE-2 is specifically designed to quickly and precisely locate gamma-ray bursts, permitting other observatories, such as the NASA Chandra X-Ray Observatory, to obtain more details of the bursts.
A new mission to investigate GRBs has now started. The Swift Gamma Ray Burst Explorer satellite became fully operational in April 2005. Swift includes a "burst alert telescope" to alert the spacecraft of any gamma-ray burst. The satellite will then quickly realign itself to focus more sensitive instruments on the burst. Swift can shift 50 degrees in less than 50 seconds to focus on a precise sky coordinate.
On May 5, 2005, Swift spotted and followed a burst that was also scrutinized by other observatories. Its data suggest it might have been created by two neutron stars colliding. The investigation of this object is ongoing at this time.

## Major changes coming

Hi everyone,

I'm a graduate student at UC Berkeley working in GRBs, and at the recommendation of my advisor am about to being a major overhaul of this page. While the amount of information contained in here is actually pretty impressive, the treatment is somewhat outdated (with a few updates hacked in here and there), there are quite a few factual errors, quite a few things are left out, the organization is not very good, there are almost no references... etc. This page has been flagged as needing 'expert' attention, which I guess I qualify as, so over the next few days I will be replacing the large bulk of the text with my own writings (though I have borrowed a few paragraphs here and there from the current version.) Please let me know if this is a problem.  :) Also, I'm kind of a wiki neophyte so please feel free to correct any mistakes, poor formatting, convention violations, etc.

For tonight I'm just going to update the intro, but you'll be seeing quite a few more changes in the following few days.

--Daniel Perley 07:41, 5 August 2006 (UTC)

## Major revisions complete

I've finished the planned revision of the article. I still plan to make some minor changes - in particular, I need to upload some images with captions - but otherwise I think I'm finished. Please let me know what you think of the new article and feel free to make any further improvements.

The article did end up going over the 32kB recommended limit I wasn't previously aware of... for now it's not a big deal, but perhaps some text can be trimmed if necessary or parts can be split out into other articles.

--Daniel Perley 10:49, 7 August 2006 (UTC)

P.S. - I have e-mailed the link to this article to a number of scientists in the field from various institutions which my group often collaborates with, encouraging them to read the article and make any corrections and changes, to help ensure the accuracy of the new article. --Daniel Perley 20:44, 7 August 2006 (UTC)

## On GRB 971214 and the energetics of GRBs

So, this correction deserves a bit of explanation.

There was a recent edit to the section on "Notable GRBs", adding GRB 971214 with the note that 'As of 2005, the most energetic event in the universe'. (This claim was also present on the original version of this article, before the recent revision.) This is no longer believed to be correct, for two reasons.

(1) GRBs are beamed, not spherically symmetric. The claim about 971214 was based on the assumption that GRB explosions are spherically symmetric, which is now known to be incorrect. The energy of GRB 971214 was almost certainly funneled into an extremely narrow angle that happened to be directed at Earth, so it looked very bright to us even though the energy release was about the same as most other GRBs. (It is generally believed that the majority of GRBs actually have about the same total energy release, with the apparently different energies arising due to differences in the beam ingangle.) Unfortunately, there was no measurement of the beaming angle of this burst, so there is no way to tell what its exact energy release truly was, but it is extremely unlikely that it was in any way record-breaking or unusual. (See the section on Distance Scale and Energetics for additional information.)

(2) There have been many "brighter" events since then. GRB 971214 was only the third GRB for which a redshift was measured and any sort of energy estimate was possible. However, even using the (incorrect) assumption that GRBs are spherically symmetric explosions, there have been many more energetic events since then - the most energetic to date would be GRB990123, which is already in the table. (Actually, even if we correct for beaming to estimate the "true" energy release, I believe the most energetic GRB is still 990123. However, it is a very tiny fraction of GRBs which we can accurately measure their true energies, so this claim may not have much meaning.) So even by its own assumptions, this claim was only accurate for even a year or two at most.

So, a correct statement might be, "As of 1997, this was believed to be the most energetic event in the universe". However, since this claim has been proven wrong (and this burst is actually quite typical for GRBs), I don't really think this GRB is really notable in any sense except maybe a historical one due to the (undeserved) hype surrounding it after it was first discovered. Furthermore, even in 1997-1998, many researchers were extremely skeptical of the discoverer's claims that this was the most event ever discovered and suspected the energy was probably beamed into an angle, even though that model of GRB emission had not yet been proven at the time.

... Still, since I guess some of this hype is still around (and to avoid orphaning the burst's own page) I'm going to reluctantly keep it in there for now with the above note replacing the earlier claim.

References:

Both these articles contain tables of GRB energies under the spherical assumption (the energy calculated by this method is called ${\displaystyle E_{iso}}$), and the Frail article also corrects for beaming where possible under the ${\displaystyle E_{\gamma }}$ column.

--Daniel Perley 09:56, 20 August 2006 (UTC)

Ok, thanks for clearing this matter up with your detailed explanation. I only placed it back on the Notable GRB list for historic reasons indeed (I browsed to Category:Gamma ray bursts and noted it was listed there, but not in the main article).
Also, I think the article is a bit too short on it's introduction/describtion. Compare this old version [[1]] with the current...
I think the section 2 to 4 of the current revision are a bit too detailed, and perhaps should be shifted to a new article: Gamma ray burst (theories). Note that the current revision is almost 48kb in filesize, more than wiki's desired page length.
--User:patrick1982 18:39, 20 August 2006 (UTC)
I don't think that there would be much advantage to splitting this article, as anyone who reads past the introduction would want all of the content. Making the introduction comprehensive enough that someone _could_ stop reading there, though, would be useful. It seems adequate as-is, though suggestions for improvement are of course welcome. Much of the information from the section you'd linked seems like it would be better off in an introduction to the "history" section, though.
I look forward to seeing what the two of you do with this article (still mostly on sabbatical over here). --Christopher Thomas 17:00, 20 August 2006 (UTC)

Well - The section you linked to for the old article isn't really the introduction, as it is imbedded in the middle of the article - and I think anyone who had read that far would really be looking for more than a brief introduction anyway. The actual introductory content (that is, before the outline) of the previous article was about as long as the introduction now; about two paragraphs. Looking at the format of other Wikipedia entries I think this is about appropriate. Most of the sub-topics have introductions for those looking for a little more detail but who don't want to read the full article. (Further, sections 1-2 also provide a historical introduction to the topic.)
I am open to ideas about splitting the article to reduce the filesize, but it is difficult to think of a good way to do this. Section 2 contains most of the foundations of GRB astronomy (distance, beaming, etc.), Section 3 is what I think 95% of Wikipedia users will be most interested in. Section 4 is admittedly quite technical and probably of little interest to most users, but contains nearly all of the physics (and so is just as fundamental as the section on progenitors). And I can't help but find titles like GRB Emission, GRB Theories, GRB History, etc. kind of contrived. So... since Wikipedia provides a nice outline at the top of the page, I figure that most users can just click on the section they're most interested in anyway without worrying about other sections if they're not as interested. But... we are over the informal "limit", and if there is a good way to split off fragments of the article in a way that doesn't impede the flow of the article as it is that might not be a bad idea. --Daniel Perley 21:19, 20 August 2006 (UTC)

## Xray flaring in short GRB's

However, the picture is clouded somewhat by the observation of X-ray flaring[26] in short GRBs out to very late times (up to many days), long after the merger should have been completed

The cited article appears to be talking about long GRB not short ones. --Albert.white 11:51, 1 September 2006 (UTC)

Hi Albert,

This is true, the article focuses on X-ray flares in general, not just in short bursts. (This is why I made the citation before the reference to short GRBs.) However, I believe that some of the examples in the paper are of short bursts.

(I haven't yet seen an article about X-ray flares in short bursts specifically, though one might be out there. If you know of one perhaps that would make a better reference than the link that's there now.)

-- Daniel Perley 00:18, 2 September 2006 (UTC)

## List of doomsday scenarios

OMG, I just heard! We are all going to die in 2012 from a massive Gamma Ray Burst from the galactic core! Cell division will cease and we will basically all starve to death no matter how much we eat! The hawrah The hawrah!!! —The preceding unsigned comment was added by 65.219.235.164 (talk) 18:29, 17 January 2007 (UTC).

## Copyedit needed

In the section, BeppoSAX and the afterglow era, there are some significant problems, but I don't want to mess with this at the risk of breaking technical information that I'm not familiar with. Here are my concerns:

• "This would be the first of many "afterglows", generally fading long-wavelength emission that lasts from days to weeks after a GRB, to be detected." – really needs to be two sentences
• "(Though not all scientists believed ..." – this parenthetical is far too long.
• "convincing even the most hardened Galactic-model advocates" – A bit over-dramatic.
• "The message was clear" – This is bordering on POV. We should describe the theory that won out and why without editorializing.
• "By finally nailing down the distance scale ... providing a new window on GRBs" – Is there a non-carpentry metaphor we could use here?
• "this discovery revolutionized the study of GRBs." – That really needs a cite, as it is such a strong statement.

Thank you to whoever may feel qualified enough to fix these problems. -Harmil 09:53, 8 October 2006 (UTC)

Well, the discovery of the first afterglow was a big deal. But I see your point(s). When I get a chance this week I'll try to make some adjustments. --Daniel Perley 09:08, 9 October 2006 (UTC)

## Far side of the moon?

I'm a bit confused by this statement about the Vela's: "specifically on the far side of the moon". This seems to be suggesting that the Vela's were designed to spot nukes in deep space. This seems unlikely, the Vela's were designed in the 50's, and I don't believe anyone had the capability for deep space testing at that point. Even if they had, data collected from such a test seems unlikely to be of real value, especially compared to less complex underground tests. So were the Vela's really designed for deep space detection, or was that a lucky coincidence? Maury 23:01, 20 November 2006 (UTC)

The satellites were most certainly designed to detect terrestrial nuclear detonations; specifically, they were designed to enforce the NTBT signed in 1963. Detecting GRBs was entirely a side-effect. siafu 00:21, 21 November 2006 (UTC)
"The satellites were most certainly designed to detect terrestrial nuclear detonations"; exactly, so that leads me to believe that they were not designed to look for explosions on the far side of the moon! Maury 04:25, 21 November 2006 (UTC)
I've already removed the offending phrase. siafu 04:35, 21 November 2006 (UTC)

## Intro

This article speaks at the start as though the ' Big Bang ' theory we're completely unquestioned as fact, and therefor, is unneutral.

I'll be changing it to the " Proposed Big Bang theory "--75.48.115.38 06:58, 18 September 2007 (UTC)

The Big Bang theory is generally accepted as the leading scientific theory on the creation of the universe. As per Scientific method the leading theory is the closest thing to fact, till proved otherwise. Also your edit linked to a fictional article. Neobros 07:04, 18 September 2007 (UTC)

## Good article nomination on hold

This article's Good Article promotion has been put on hold. During review, some issues were discovered that can be resolved without a major re-write. This is how the article, as of October 10, 2007, compares against the six good article criteria:

1. Well written?: Yes, it is well written. However I would suggest merging "Progenitors: what makes GRBs explode?" and "Emission mechanisms" sections into the previous section, possibly as subsections. In addition, the second paragraph in 'Progenitors: what makes GRBs explode?' section is not necessary, because it duplicates the previous section.
2. Factually accurate?: Yes, the article is generally well cited. However I want to see a citation for "Notable GRBs", a citation for the second paragraph of "Extragalactic nature of GRBs" subsection, a citation for the last two sentences of the second paragraph of "GRB Jets: collimated emission" subsection and a citation for "Emission mechanisms" section (after its merger with previous section).
4. Neutral point of view?: No problems
5. Article stability? Yes
6. Images?: Ok

Please address these matters soon and then leave a note here showing how they have been resolved. After 48 hours the article should be reviewed again. If these issues are not addressed within 7 days, the article may be failed without further notice. Thank you for your work so far. — Ruslik 13:40, 10 October 2007 (UTC)

### Progress report

1. Well written?: Yes, it is well written. However I would suggest merging "Progenitors: what makes GRBs explode?" and "Emission mechanisms" sections into the previous section, possibly as subsections. In addition, the second paragraph in 'Progenitors: what makes GRBs explode?' section is not necessary, because it duplicates the previous section.
2. Factually accurate?:
A.Yes, the article is generally well cited. However I want to see a citation for "Notable GRBs", Cited
B.a citation for the second paragraph of "Extragalactic nature of GRBs" subsection, unciteable - deleted
C. a citation for the last two sentences of the second paragraph of "GRB Jets: collimated emission" subsection unciteable - deleted
D.and a citation for "Emission mechanisms" section (after its merger with previous section). modified and cited
4. Neutral point of view?: No problems
5. Article stability? Yes
6. Images?: Ok

I need an expert to help with the few remaining citations that are still missing. Any takers? - Jehochman Talk 17:44, 10 October 2007 (UTC)

I've done my best to resolve the remaining concerns. I had to delete a few things that I couldn't source. Feel free to check older versions of the article and add that stuff back in, or expand what we have with additional sources. - Jehochman Talk 14:55, 12 October 2007 (UTC)

Since formally all my concerns were acted upon I will promote this article to GA status, although I do not think that those statements were uncitable. Ruslik 18:48, 13 October 2007 (UTC)

When I tried to find citations, I discovered that the statements either relied upon a paper to which I could not access, or they might have been synthesis. Additionally, they did not seem critically important to the article, so I felt that best result was to remove them, at least temporarily. Perhaps an expert could help sort this out as we continue preparing the article for featured article candidacy. Thank you for your help! - Jehochman Talk 20:15, 13 October 2007 (UTC)

## Semi Automatic Peer Review

Semi Automatic Peer Review has been completed for this article to help achieve GA. Good luck! —Preceding unsigned comment added by SriMesh (talkcontribs) 02:19, 8 October 2007 (UTC)