Talk:Very-high-energy gamma ray

Requested move (September 2012)
Ultrahigh energy gamma-ray → Ultra-high-energy gamma ray – For consistency with ultra-high-energy cosmic ray, gamma ray, and what most other people do. &mdash; A. di M.  21:14, 16 September 2012 (UTC)
 * I am looking at academic type article results with these results
 * Gamma-Radiation at Ultrahigh Energies
 * Ultra High Energy Gamma Ray
 * Ultra high energy gamma-rays
 * ultra-high energy gamma photon
 * ultra-high energy gamma radiation
 * Ultra high-energy gamma-ray
 * Ultra--High-Energy Gamma-Ray
 * ultra-high-energy gamma rays
 * Ultra-high-energy Gamma-ray
 * ultra-high energy gamma-ray
 * ultra-high energy gamma rays
 * ultrahigh-energy cosmic gamma-ray
 * Ultrahigh energy gamma-quanta
 * ultrahigh energy gamma radiation
 * ultrahigh energy gamma-radiation
 * Ultrahigh-energy Gamma-ray
 * ultrahigh-energy gamma-ray
 * Ultrahigh-Energy Gamma-Ray
 * ultrahigh energy gamma-rays
 * Ultrahigh-Energy Gamma Rays
 * ULTRAHIGH-ENERGY GAMMA-RAYS
 * ultrahigh-energy gamma-rays
 * Ultrahigh-energy gamma rays


 * There are actually only a very few uses with the proposed title Ultra-high-energy gamma ray, but a large number of other alternatives to hyphenation (or not). So at this time there seems to be no standard way to write it.  Which means that a move is pointless, it will go from one minority use to another.  And for the MOS enthusiasts, is the - a – or a —; ndash  or hyphen? Graeme Bartlett (talk) 12:24, 17 September 2012 (UTC)
 * ndash. But the move seems pointless. Apteva (talk) 05:02, 19 September 2012 (UTC)


 * Support Ultra-high-energy gamma ray as the most clearly meaningful use of of normal English punctuation. Those are hyphens; there are no reasons I can see to involve any kind of dash here; see WP:HYPHEN and WP:MOSDASH.  Dicklyon (talk) 00:50, 25 September 2012 (UTC)

10 EeV gamma rays?
In the second paragraph of the section "Importance" it says, "The fraction of gamma rays compared to cosmic rays above 10 EeV was under 2% as measured at the Pierre Auger Observatory." According to the lede, the most energetic gamma ray ever measured was 16 TeV. 10 Eev is nearly six orders of magnitude above that. Just poking around on the web, it looks as if there is a wide range of reported energies for gamma rays, with varying degrees of confidence. Everyone seems to agree that 16 TeV is reasonably solid (although I'm not sure if it meets the five sigma criterion). Then there are some possible sightings of >30 Tev gamma rays, but with considerable uncertainty. Even though lots of people are looking for the elusive PeV gamma ray, I can't find any indication of any having been found. Finally there is this one observatory in Argentina that is talking about "photon candidates" in the >10 Eev range (with 95% CL). However, this claim does not seem to be widely cited or acknowledged in the literature. What's up with that? Zyxwv99 (talk) 02:12, 1 August 2014 (UTC) UPDATE The 10 Eev gamma rays are simulations. I think we should remove the sentence, "The fraction of gamma rays compared to cosmic rays above 10 EeV was under 2% as measured at the Pierre Auger Observatory." Zyxwv99 (talk) 03:20, 5 August 2014 (UTC)
 * removed. Graeme Bartlett (talk) 09:53, 5 August 2014 (UTC)

More problems
There are several conflicting definitions of UHE gamma rays, but I think the one in the lede is currently the most widely used, i.e., 100 Tev-100 PeV. As high-energy photons are generally measured in electron volts, this is the primary definition. Equivalents for frequency and wavelength are approximations rounded to the nearest log unit. There is almost nothing in this article about UHE gamma rays by this definition. Some sources are actually about cosmic rays, or are using "ultra-high-energy" in a different (usually older) sense. This is too much for me to try to fix at this time, but I think a good place to start would be to create an article on Very-high-energy gamma rays. Some material here could then be migrated to the other article. There are actually exciting developments in the field of UHEGR research, as several new observatories are coming online to look for them. They should be finding some soon. As of now, however, no UHEGRs have been detected. Incidentally, an 86 TeV gamma ray was detected from the Crab Nebula, the highest energy ever recorded. Also, one at 80 TeV. Zyxwv99 (talk) 03:13, 7 August 2014 (UTC)
 * How about we rename this to very high energy gamma ray, which is actually a redirect to here anyway, and then the content can be cleaned. Do you think there is enough material on UHE as per definition?  THere were plenty of article talking about UHE, but the article basically includes the coverage, even if the definition is not matched, because others have a different definition. Graeme Bartlett (talk) 08:23, 8 August 2014 (UTC)

Before making any major changes, it might be a good idea to try to develop a consensus on nomenclature and definitions. At the opposite end of the electromagnetic spectrum one of our editors has created a series of articles based on the radio bands defined by the ITU (International Telecommunication Union). (see Radio spectrum)

At the opposite end of the spectrum (gamma rays) there is no widely accepted system. Although gamma-ray astronomers use the same terms (HE, VHE, UHE, etc.) each project has its own definition of what range it refers to. A project is usually a gamma-ray observatory or satellite with a life-span of maybe 7 years, by which time the equipment has become obsolete. Each project just makes up new definitions as they go along.

So far I have found only two decent sources for something comparable to what the ITU has, one by Weekes (Very High Energy Gamma-Ray Astronomy) and one by Aharonian ([http://www.isdc.unige.ch/sf2010/lectures/FA_Lecture_1_2.pdf see page 5).

I propose that we use the one by Aharonian, as it seems to be more regular and comprehensive.



UPDATE Sorry, forgot to sign that last post. I also forgot to answer the question. I think it would be better to split this article in two, as I can come up with more material for UHEGR. Do you want to do it or shall I? Zyxwv99 (talk) 22:08, 10 August 2014 (UTC)
 * You may as well do the split, as you have the extra info for the "real" UHEGR. I would just move this off to very-high-energy gamma ray and then copy some content to the redirect to explain what the UHEGR is, if I did a split. I would expect that EHEGR could be included with UHEGR at this point, unless you have extra info on EHE stuff. Graeme Bartlett (talk) 12:06, 11 August 2014 (UTC)
 * I just realized something. If we split and migrate most of the material to a new article, the history page will become disconnected from its content. Also, I would like to have more time to compile material for UHEGR. For this reason, I think your idea is better. I don't know how to rename an article. Does it take an administrator? I copied the entire article (in edit mode) into a rich-text file, so I can salvage whatever material and references are needed for UHEGR. Zyxwv99 (talk) 13:18, 11 August 2014 (UTC)
 * The pasge will have to be moved over the redirect, so I will do that and create a bit of a stub for the UHE page, then you can add to that. Graeme Bartlett (talk) 22:19, 11 August 2014 (UTC)
 * Thanks! Zyxwv99 (talk) 00:29, 12 August 2014 (UTC)
 * (Just corrected an error in the above table. Wavelength exponents were off by three.) Zyxwv99 (talk) 03:22, 12 August 2014 (UTC)
 * I was using the table, so please check the article content too! Pages are at Very-high-energy gamma ray and Ultra-high-energy gamma ray. Graeme Bartlett (talk) 07:28, 12 August 2014 (UTC)
 * I did. First I double- and triple-checked the numbers, using a variety of tools. Then I changed the ledes on both articles. Zyxwv99 (talk) 13:19, 12 August 2014 (UTC)

Highest energy detected
In the lede and in the table, there is a mention "16 TeV highest energy detected". This is also mentioned in Ultra-high-energy gamma rays. I believe this is incorrect, caused by someone mis-reading an article (and not the one specified as the reference, it doesn't even mention it). 16 TeV probably is the highest energy detected from that quasar, but not the highest energy photon detected. This article talks about detection of photons in the PeV range. The comment on page 3:
 * At higher energies, extra-galactic sources are unlikely to be visible, because more energetic photons are predicted to interact with cosmic microwave background radiation (CMBR), and with infrared starlight from early galaxies, producing e+e− pairs. At 1 PeV, for example, photon propagation is limited to a range of about 10 kpc. It is unknown whether Galactic accelerators exist that can produce gamma rays of such high energy, but an expected flux results from interaction of (extragalactic) CRs with the interstellar medium (ISM) and dense molecular clouds.

explains why 16 TeV from that quasar would be remarkable even though we detect higher energy photons from closer to home. Anyone care to comment before I remove the mention of that photon? Tarl.Neustaedter (talk) 12:20, 1 April 2016 (UTC)
 * May as well take it out. I added it, but I can't see what reference it came from, it is not the one at the end of the sentence. Graeme Bartlett (talk) 23:05, 2 April 2016 (UTC)
 * Done. Tarl.Neustaedter (talk) 11:58, 3 April 2016 (UTC)