Talk:List of most massive black holes

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#Revisiting astronomy lists. 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 1.8×10¹⁰ M_☉ is likely to be underestimated and the lower one, while being somewhat reliable, was based off of low-resolution imaging. SpaceImplorerExplorerImplorer 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 2.7×10¹¹ M_☉. This much larger value has been mentioned to be the 'absolute' maximum mass for all accreting black holes. SpaceImplorerExplorerImplorer 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? SpaceImplorerExplorerImplorer 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 r_s 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 [1] although many black hole spins are not known. If we do include the Schwarzchild radius, there should at least be a note. SpaceImplorerExplorerImplorer 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)

Oei et al. (2023)

Can someone investigate and raise your thoughts on this paper? It has quite some massive candidates, including a reported 2×10¹¹M_☉ and two other 5×10¹⁰M_☉. SkyFlubbler (talk) 16:10, 2 August 2024 (UTC)

I wouldn't pay too much attention to those. In section 3.6.4 of that paper they explain that they are just taking the standard SDSS pipeline-measured velocity dispersions and then applying the M-sigma relation to estimate the BH mass. There's no checking on the reliability of these velocity dispersions, and there's a lot that can go wrong in situations like this including just bad measurements from low S/N spectra, or spuriously high velocity dispersions due to line-of-sight projection of another galaxy within the primary galaxy's close environment. In general you just have to be really cautious about outlier values taken from automated measurements done on huge catalogs of data, so unless there is some additional checking and verification based on a more dedicated analysis of the SDSS data or better quality data, these should not be included in the list. Aldebarium (talk) 16:53, 2 August 2024 (UTC)