Talk:List of most massive black holes

Theoretical limit
What am I missing?

Limit is stated as 5×1010 Phoenix A is estimated as 1×1011 109.78.0.127 (talk) 13:30, 5 May 2023 (UTC)
 * The mass of that object has yet been measured directly or reliably. Nerd271 (talk) 14:31, 5 May 2023 (UTC)
 * Why is it even on the list then? It is quite misleading. VY Canis Majoris  (talk) 07:57, 7 May 2023 (UTC)
 * Well, there is a cautionary note near the top. It reads, "The above masses are larger than what is predicted by current models of black hole growth, and are thus potentially unreliable." Nerd271 (talk) 17:17, 7 May 2023 (UTC)
 * Fair note: while the mass of Phoenix A is indeed indirect, that number has been mentioned in the abstract of the cited paper. SkyFlubbler (talk) 16:24, 14 May 2023 (UTC)

PKS 2126-15
Hi @SkyFlubbler - I wanted to just explain why I removed this object from the top of the list. First of all, it was already entered in the list farther down (as QSO B2126-158), and it shouldn't have 2 different entries in the list. But more importantly, published values for the mass in this object are all over the place, so while the mass is certainly very large, it seems highly dubious whether it is really the largest known BH mass in a quasar. The reference that you cited states that the mass was estimated from Hbeta, but it doesn't seem to show the spectrum or any details of the measurement, so this is yet another case of a numerical value being listed in a large catalog without enough information to really evaluate its accuracy. As I mentioned in my edit comment, the paper by Shemmer et al 2004 gets a value for the BH mass, also measured from Hbeta, that is smaller by an order of magnitude, and they show their data and give more information about their measurement. In your edit comment you said that the Shemmer result was based on UV data from a paper by Dietrich, but that doesn't seem to be correct: Shemmer's measurement was from near-IR spectroscopic data that they displayed in the paper, not from earlier UV data. The citation to Dietrich's work was for rest-frame UV observations, but not for the near-IR (rest-frame optical) data that was actually used to derive the BH mass from Hbeta. Also you stated that Shemmer's BH mass value was based on a Hubble constant of 65, but if you look at their paper they directly say that they used H0=70 to calculate luminosities. Additionally, in the table entry you described PKS2126 as an "OIII broad spectrum quasar" but that isn't a meaningful description: that's not terminology that would be used in astronomy to describe this kind of object. It might be better described just as a radio-loud quasar. Anyhow, this object should certainly be listed in the table, but it was already listed, and maybe just needs a bit more description to explain that its BH mass is very uncertain since published estimates for the mass span an order of magnitude. Aldebarium (talk) 19:07, 22 August 2023 (UTC)


 * Okay. So here is my response.
 * "'First of all, it was already entered in the list farther down (as QSO B2126-158), and it shouldn't have 2 different entries in the list.'"
 * Yes, you have mentioned this in your revert. That is why in my revert edit, I have also deleted ths lower entry in the list. A honest mistake on my part given that I don't know this was already included. Next;
 * "'The reference that you cited states that the mass was estimated from Hbeta, but it doesn't seem to show the spectrum or any details of the measurement, so this is yet another case of a numerical value being listed in a large catalog without enough information to really evaluate its accuracy.'"
 * That is not true, by the way. Here is the website of the BASS Survey DR2 by Koss et al. that shows the 1,449 entries and their spectra, including this object, which you can download and check.
 * "'In your edit comment you said that the Shemmer result was based on UV data from a paper by Dietrich, but that doesn't seem to be correct: Shemmer's measurement was from near-IR spectroscopic data that they displayed in the paper, not from earlier UV data. The citation to Dietrich's work was for rest-frame UV observations, but not for the near-IR (rest-frame optical) data that was actually used to derive the BH mass from Hbeta.'"
 * Partly true, but that does not mean my reason is wrong. You just don't need the near-IR data, you also need the N V and C IV data. The Shemmer 2004 paper still based its N V and C IV data from Dietrich (2000). Apart from the near-IR data, you also need data on the N V and C IV to get the FWHM of the Hβ line, not just the former. That is why Shemmer (2004) chose the 29 quasars they have precisely because there are previous papers detailing the measurements of their N V and C IV lines. It's not just because of one measurement.
 * "'Also you stated that Shemmer's BH mass value was based on a Hubble constant of 65, but if you look at their paper they directly say that they used H0 = 70 to calculate luminosities.'"
 * I did not say that, by the way. What I exactly said is: "The estimation by Shemmer 2004 was based on emission line data by Dietrich & Wilhelm-Erkens (2000), which not only used old models from the 90s, but also used small cosmological parameters (H0 of 65 km/s/Mpc against the modern ~69 km/s/Mpc)."
 * And by "which" I am now referring to Dieterich (2000). Indeed if you look at their paper here, this is exactly what they stated: "Assuming an evolution time scale of ~ 1 Gyr and a cosmological model with Omega _M =~ 0.3, Omega _Lambda =~ 0.7, and H_o =~ 65 km s-1 Mpc-1 the first violent star formation epoch should start at a redshift of z_f =~ 6 to 10."
 * But I do agree that it is a vague description. Either way, that sort of OIII broad spectrum characteristic is mentioned in the data entry of the object in the BASS Catalog, so I might as well keep it for precision purposes. Might as well call it a "broad-spectrum, radio loud blazar." SkyFlubbler (talk) 20:08, 22 August 2023 (UTC)


 * Hello- thanks for your reply. I think you actually deleted a different quasar from the list by accident, which is why the duplicate entry for this quasar is still there. (Previously I didn't notice that you had deleted an object from the list in your edit, I just noticed that the duplicate entry for PKS 2126-15 was still there.) The object you deleted was PKS 2128-123 from Oshlack et al 2002, which is at redshift 0.499 and is a different quasar. So that listing should be restored, and for PKS 2126-15 the two entries should be merged into one. About the BASS catalog, I looked at the link you gave to the BASS DR2 catalog and I don't see this object listed on that page. The quasar's SWIFT designation is either SWIFT J2129.1-1538 or SWIFT J2129.3-1536 according to NED, and maybe I'm looking in the wrong place but I don't see either of those listed on that BASS DR2 catalog page. Looking at the BASS DR1 catalog page, this quasar is listed as object #1112 but there's no spectrum shown for it there, and in the DR2 catalog page there's no entry for object #1112. In the BASS file of DR2 downloadable spectra there is spectroscopic data for object #1112 but only in the observed-frame optical, and this doesn't seem to contain the near-IR spectrum that they apparently used to calculate the BH mass from the Hbeta properties in the BASS paper. It may be there somewhere but I don't see the Hbeta portion of the spectrum anywhere on the BASS site. Did you find a plot or the data for the Hbeta portion of the spectrum on the BASS site? If it's there I didn't find it in my quick glance at their site but I'd be interested to see it. Anyhow, my main point is that the BASS paper just doesn't seem to contain enough detail to be able to judge whether their measurement is any better than the earlier measurement by Shemmer, or why it's so different. The Shemmer paper actually shows a plot of their near-IR spectrum and the model fit to it, which gives much more useful information to evaluate the result. Beyond that: It is not correct to say that you need the NV or CIV data to get the FWHM of the Hbeta line. The Hbeta FWHM is something you can measure from the Hbeta line itself, in the observed near-IR spectrum, without any UV data at all, as shown in the plot in Shemmer's paper (figure 3). In that paper they calculated the BH mass from their near-IR data, using equation 1 in their paper. This equation doesn't depend at all on the UV data, and neither does the measurement of FWHM(Hbeta). Shemmer et al used the NV/CIV measurements as a metallicity indicator but not to determine the BH mass, from what I can tell in their paper. And, the Hubble constant value assumed by Dieterich is not relevant here because it doesn't enter into Shemmer's calculation of the BH mass, because the BH mass calculation only depends on L5100 and FWHM(Hbeta) which are measured from the near-IR data. In the end the best outcome here would be to have this object listed in the table with a mass range spanning between about 5e9 and 5e10 solar masses with citations to Shemmer et al 2004 and to the BASS paper, and an explanation that published values in these different papers are highly discrepant. Aldebarium (talk) 21:51, 22 August 2023 (UTC)


 * Just following up on this, I'm going to delete PKS2126-15 from the top of the list again, since (for the reasons described above) I don't think it really should be at the very top of the list, and the previous entry for it farther down in the table seems sufficient. Aldebarium (talk) 00:14, 30 August 2023 (UTC)

Revisiting the list
Hello. I wanted to let you know that I have made a workpage (or sandbox) to rewrite the list in order to make it better organized given this list is a mess and has some problems, such as no cutoff point and mass estimates from older or less reliable sources.

I've also added event horizon radii in the table as well based on the parameters of black holes. This is also because there is likely no need to make the List of largest black holes (by radius) as a seperate list or article from the one by mass, considering more massive black holes are in general larger in term of size as well according to the Schwarzschild radius. However, it should be noted that the radius also depends on three quantities (mass, spin parameter, and electric charge) per no-hair theorem, with the radius becoming smaller assuming a black hole with nonzero spin and/or electric charge. For this reason, I've also added the spin paramater in the table, but not electric charge as explained in my linked sandbox page.

See also User talk:SkyFlubbler/Archives/2023/October. Regards— ZaperaWiki44 (✉/Contribs) 16:32, 5 October 2023 (UTC)

Remove Pheonix A*?
I’ve heard multiple sources saying it is an overestimation, and inaccurate. It is also double the size of the theoretical limit. I think we should remove it unless it is somewhat reliable. Atlantlc27Lol (talk) 22:57, 5 December 2023 (UTC)


 * What multiple sources? SEA's video on YouTube? That video actually makes a lot of hodge-podge points (like claiming it is an "old method" despite the paper title explicitly stating it is a novel one). It is actually kind of misleading.
 * Unlike stars, the theoretical limit on black holes is not a hard one. It assumes if the black hole is in an active state of accretion and generates energy to create some Eddington feedback. This does not take into account dark matter (who knows if they heat up when accreted or not) or mergers of SMBHs, which is quite common in the early universe. If taken into account those (and a few other things), the limit jumps to 200 billion or so.
 * Black holes are not like stars. They can absolutely defy our expectations. This estimate is actually not far from others (take IC 1101 at 70 billion M for example, or Holmberg 15A previously at 310 billion M). The Phoenix Cluster estimate may seem to be oversized, but here in Wikipedia we go for the best and most recent estimates. And the 100 billion M is the best one we have. Unless some newer source states a lower mass, this will remain here. SkyFlubbler (talk) 10:51, 14 December 2023 (UTC)
 * There are already 2 other mass estimates. Universe Explorer added them (or at-least one) and lowered Phoenix A*, but it was undone. If we aren’t going to remove or lower down Phoenix A*, then at-least keep the other estimates. Atlantlc27Lol (talk) 23:33, 16 December 2023 (UTC)
 * I added them, however, one paper mentioned that is likely to be underestimated and the lower one, while being somewhat reliable, was based off of low-resolution imaging.   SpaceImplorer ExplorerImplorer   14:31, 19 December 2023 (UTC)
 * I mean, applying the adiabatic core regrowth method is relatively new, not as reliable as the x-ray/mir data or any other correlation used to measure the masses of ton 618 etc, as supported by the ESO group, not to mention the fact that nasa has not taken this smbh into account due to its data inconsistency. 100 billion solar masses is indeed a number that is just too high to comply with the growth model we have today, and any merger giving rise to phoenix a would come with evidences surrounding the cluster. I think the x-ray data signalling a mass of 12 billion m0 is more reliable than the 100 billion m0 measurement. Hboeing (talk) 03:14, 12 June 2024 (UTC)
 * Technically, it is smaller than the limit for some accreting black holes, which is . This much larger value has been mentioned to be the 'absolute' maximum mass for all accreting black holes.  SpaceImplorer ExplorerImplorer   11:06, 8 January 2024 (UTC)

Distance column
A suggestion: add a distance column — Preceding unsigned comment added by 46.1.178.152 (talk) 11:59, 26 March 2024 (UTC)


 * Why should it be in here?  SpaceImplorer ExplorerImplorer   11:42, 30 March 2024 (UTC)
 * Agree. A section with the Schwarzschild radius of the black holes would also be useful. There is a website that calculates radius from mass. InTheAstronomy32 (talk) 14:48, 30 March 2024 (UTC)
 * No black holes are Schwarzchild black holes though, therefore the rs wouldn't really work as a good representation of a black hole's radius. The formula for Kerr black holes (which may also not exist if black holes have charge) is $$r_{+}=\frac{GM}{c^{2}}+\left[\left(\frac{GM}{c^{2}}\right)^{2}-\left(\frac{J}{Mc}\right)^{2}\right]^{\frac{1}{2}}$$ per although many black hole spins are not known. If we do include the Schwarzchild radius, there should at least be a note.   SpaceImplorer ExplorerImplorer   11:42, 3 April 2024 (UTC)
 * Adding distance information would potentially be confusing if it isn’t very specifically defined. A galaxy’s redshift is a directly measurable quantity but distance estimates will generally depend on cosmological model assumptions and/or distance measurement methods, and be subject to larger uncertainties. And “distance” can be a luminosity distance, an angular size distance, a light-travel time distance, etc. For purposes of estimating the angular size of the Schwarzschild radius, the angular size distance is most relevant, but for non-experts it would probably be confusing to specify angular size distance as the listed quantity since that doesn’t correspond in a simple way to an intuitive notion of how “far away” an object is, at least not without a lot of additional explanation. It definitely would not be useful to list multiple different kinds of distances for each object. Given all of these concerns my preference would be to not list a distance at all. Aldebarium (talk) 15:05, 3 April 2024 (UTC)