Talk:Cygnus X-3

Ambiguity

In the second sentence which reads "Although it is only the third brightest x-ray source in the constellation after the famous Cygnus X-1, it is much further away on the far side of the galaxy and is obscured by intervening interstellar gas and dust near the galactic plane," does the second it refer to X-1 or X-3?

It refers to Cygnus X-3. Cygnus X-1 is about 7,000 light years away and its companion star HDE 226868 is 9th mag (ie, bright), while Cygnus X-3 about 30,000 lt-yrs distant, and so heavily obscured by interstellar dust and gas that no object is visible at all except in the infrared. Wwheaton (talk) 20:07, 18 March 2009 (UTC)

Many of the parameters in the infobox are simply marked as known (?). Is this due to lack of information within Wikipeadia or that the parameters have never been measure with current instruments? Anthony Rushton (talk) 10:09, 19 October 2008 (UTC)

SOUDAN events

An editor has lately attributed the 4.79 h periodic signal from Cyg X-3 in the Soudan to neutrinos or gamma rays. The latter possibility seems untenable due to the strong interactions of gamma rays with atmosphere and earth, the suppression of which is why the observatory there is so deeply buried. High-energy neutrinos are surely possible, or else in principle some other unknown particle, of very low (or zero) rest mass and very weak interaction with normal matter. I am going to remove the gamma-ray alternative from the article, pending further editorial input. Wwheaton (talk) 20:16, 18 March 2009 (UTC)

I did. IMO unknown particles are too hypothetical yet to be presented as more plausible candidates than neutrinos or photons. Cygnus X-3 is known to be a TeV gamma ray source, and given its burst history it is not unlikely that a strong gamma ray burst with a hard photon index would have produced photons with sufficient energy (as a galactic object there is no cutoff at 100 TeV) to produce very high energy muons in the atmosphere, which would have reached the detector. I think this is the most plausible scenario (but I would be glad if you provided me some counter-arguments or, better, some papers refuting this hypothesis). Skippy le Grand Gourou (talk) 23:47, 18 March 2009 (UTC)

Hi, The problem I worry about is that there is no credible way I know that high-energy gamma rays can produce the muons. I suppose gammas over 200 MeV might produce low-energy muon-antimuon pairs, but these would then have to penetrate a km or so of rock to reach the detectors. Same problem for photo-production of pions, I think. Also, I believe that Cyg X-3 is not known to be a strong enough gamma-ray source at high gamma energies, which are now routinely observed. I suppose we need to go look up the current upper limits for photon fluxes from Cyg X-3 at the energies required. Maybe you could find a source in the literature refuting my concerns? Meanwhile there are always lots of hypothetical particles in the theorists' bags of tricks, and we are pretty sure that at least some unknown particles must be real. Anyhow, I could be mistaken, but anything but neutrinos makes me uneasy. What do other editors think? Any comments? Wwheaton (talk) 05:21, 19 March 2009 (UTC)

Concerning production of high energy muons from gamma rays, the main processes are indeed photoproduction and pair production. Though the number of muons in gamma-induced showers is quite low, the idea to use muons from gamma rays in underground detectors for gamma-ray astronomy is considered (have a look for Francis Halzen publications, for instance). BTW, Soudan is at a 590m depth, which is quite less than a kilometer of rock. ;-)

As for the photon flux, Kiel and Havera Park observations published in 1983 suggest integral fluxes of about 10⁻¹⁴ to 10⁻¹³ cm⁻²s⁻¹ at energies about 2000-3000 TeV, by far higher than 1990 to today observations (see for instance this recent review, figure 1). Soudan muons excess having been observed in 1985, it seems to me consistent with such a high UHE gamma flux. Skippy le Grand Gourou (talk) 11:08, 19 March 2009 (UTC)

Citations

This page has improved substantially since the refimprove tag was added 2008-May, and a number cites have been added. I am removing the tag. If you disagree, please use the fact tag for explicit instances. Robsavoie (talk) 01:26, 27 December 2009 (UTC)

V1521

For a non-expert like me, this recent one-sentence section is a non-sequitur. After re-reading the entire article and still finding no previous reference to V1521, I finally spotted it in the infobox. This should be made much clearer, but I won't have time to work on it for a while. Perhaps Marshallsumter can take a look? Robsavoie (talk) 15:33, 22 April 2010 (UTC)

"The Cygnus Mystery" by Andrew Collins

Is there an objection to include a paragraph about the theory that ancient cultures were aware of the cygnus system as a unique place in the cosmos? — Preceding unsigned comment added by 78.53.73.41 (talk) 17:20, 2 May 2012 (UTC)

No, not until it can be buried at the end of a massive article, insignificant as the fringe theory that it is. Maybe not even then. Lithopsian (talk) 14:59, 9 November 2018 (UTC)

A minor mistake (typo) concerning energies of cosmic rays

Paragraph 4 begins with the following sentence: "It has also received attention because it is one of the few sources of ultra-high-energy cosmic rays, with energies in the 100 - 1000 TeV range" with a reference to the following page: https://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray The latter one defines ultra-high-energy cosmic rays (UHECR) as particles with a kinetic energy greater than 10^18 eV, which I believe is correct, see, e.g., http://uhecr.sinp.msu.ru Since 1 TeV = 10^12 eV, the above range 100-1000 TeV equals to 10^14-10^15 eV, which is far below energies of UHECRs. Thus, either the energy range must be fixed or the reference to UHECRs omitted.

More important, in case an author really means that Cygnus X-3 is "one of the few sources of UHECRs", a reference must be provided since I believe not a single source of UHECRs is currently known for sure, see, e.g., one of the latest reviews on the subject: http://arxiv.org/abs/1405.0575

213.131.12.28 (talk) 12:30, 7 May 2014 (UTC)

Further, the reference [8] claimed as support for UHECR is not to Cygnus X-3, but to a different source, Cygnus X-1 emission (at energies much less than UHECR).

There is a Cygnus X-3 reference, but it sees only photons < 250 GeV, not > 100 TeV. So it also gives no justification for Cygnux X-3 as a UHECR source.

73.18.188.225 (talk) 04:17, 19 August 2020 (UTC) (JimL)

I reworded that sentence. Ruslik_Zero 07:17, 19 August 2020 (UTC)

References