Talk:List of most massive black holes

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)

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)

I agree with Aldebarium, these estimates likely have been contamined with poor data, and hence are inaccurate. 21 Andromedae (talk) 12:29, 11 September 2024 (UTC)

No. Stop. Don't add the Schwarzschild radius.

Man, the table is garbled beyond recognition. And the code is just too messed up to fix now, but I did my best at deleting them.

Foxyhusky, as much as I encourage being bold in Wikipedia (WP:BEBOLD), such a major change like you did probably should have been in the best interest of the article, consulted here in the talk page first.

Here are my points:

• This is a list of most massive black holes, not a list of largest Schwarzschild radii. As such a dedicated column on Schwarzschild radii is out of the scope of this article. This is also pretty redundant information; just multiply solar mass by 3 to get the approximate Schwarzschild radius.

• As I noted in my edit comment, the table became too stretched. As much as possible this table should be as neat (which right now even with the state that it is clearly is not!) with just enough information, and nothing more that is too overwhelming for the reader.

• It is of best interest that major changes like what you did, especially for an article this large, should have been consulted here first. Because look, the table is just busted up and it would take a lot of fixing to restore it.

Next time, I do hope that you will contact fellow editors first on edits as large as these, or even initiate a discussion first before you make a move. No hard feelings. Thanks. SkyFlubbler (talk) 12:38, 7 October 2024 (UTC)

I've reverted to the last version with a three-column table. There's some discussion from April about adding distances and Schwartzschild radii in a section above which, at least, did not come to a consensus that they should be added. Best, Wham2001 (talk) 15:28, 7 October 2024 (UTC)

Remove SDSS J123132.37+013814.1

Hey @SkyFlubbler - I saw that you added this new object which is listed as having the highest BH mass of any quasar. I took a look at the SDSS BOSS spectrum and conclude that this mass measurement is almost certainly an error in the paper that you cited. This is a weak-lined quasar with strong absorption lines, and it is exactly the kind of object where an automated measurement of C IV line width can fail and give spurious results. Additionally, it has been listed in catalogs as a candidate blazar, which means that the continuum luminosity may be boosted by relativistic beaming, which would also tend to produce an incorrect measurement of BH mass. You have to be extremely careful about cherry-picking extreme results from giant catalogs of automated measurements like this, since the extreme outlier values are likely to be the result of measurement errors. If the authors of that catalog paper thought this was real evidence of a 10^11 solar mass black hole, they (or someone else) probably would have called attention to it, but as far as I can see there are no papers that have discussed this. All of this tells me that this is just a faulty measurement of BH mass, and Wikipedia should not call attention to this by listing it as the largest known BH in the universe. The fact that this number comes from a published journal paper doesn't really give it any credibility, since the result was generated automatically and has not been subject to any checking or verification. It shouldn't be in the table at all unless a reliable measurement can be found. Aldebarium (talk) 20:25, 29 October 2024 (UTC)

The results at the VizieR link provide some detail. While there is a singular C IV emission line, the quality of the measurement is also listed as 0. Reading at the paper at Appendix A, sources like the SDSS object which "has a quality flag of zero means all Bits are zero and the associated quantity is reliable, while a flag >0 means that the associated quantity should be used with caution" which is not the case for this one (like the earlier SDSS with 196 billion, or the ones from the Oei paper).

Here's a note. Having a sort of unusual measurement like this is not new. TON 618 was also a blazar and the measurement was based on an unusual C IV line spectra from 2004, however we still used it (66 billion solar masses) until we saw a newer source. The authors of that particular paper also did not mention TON 618 in particular. It doesn't have to be super accurate, it just has to be verifiable. Just because it is in a giant catalog of automated measurement doesn't automatically make it unreliable and should be shunned away - this is not like the list of largest stars, and there is relatively less stringency on standards here due to the nature of how massive black holes are measured in the first place.

Unless there is serious flag to the data, like another paper explicitly saying this measurement is absolutely wrong, or there is a newer, alternative measurement, this object will remain on the list. SkyFlubbler (talk) 00:49, 30 October 2024 (UTC)

The listed width of C IV is around 33,000 km/s which is not a very plausible result, and from looking at the spectrum it's clear to me that this is bound to be just a bad measurement. We have seen this exact situation before for other objects. (Remember SDSS J1408?) From the catalog paper, you can't even see a plot of their fit to the C IV line, because they don't show you that, so you can't independently evaluate the quality of the fit or the CIV measurement. Ton 618 was a very different situation. The Shemmer paper from 2004 that you mentioned had reasonably good quality infrared spectra and they showed a plot of every single model fit for each object in their sample, so there was enough information in the paper to see that this was a reasonable measurement of the emission line width, and the measured width in Ton 618 was large but not implausibly gigantic. For SDSS J123132, we are not even close to that situation: all you have is an implausibly gigantic CIV linewidth from an automated catalog, with no plots to show you the actual quality of the measurement. Given how extremely large this number is and given the quality of the data from SDSS, the simplest conclusion is that this is just a garbage measurement from an automated procedure applied to a large sample, without any human checking of any weird or extreme results. Putting an obviously wrong result like this in wikipedia has real consequences, particularly if this is listed as being the largest BH known in the entire universe. If you take a critical view of these kinds of catalog papers, it is clear that large catalogs like this will contain some garbage, and there is a very, very high prior probability that any such extremely high BH mass measured in this way is actually a spurious result. Another way to consider this is that this measurement lacks any notability suitable for inclusion in WP, because it's just a number from a giant catalog, that wasn't vetted or verified by any human, and there has been no further discussion or observational follow-up of this in the scientific literature. To astronomers, the question of what is the biggest BH in the universe is a fairly consequential question, and it's clear that nobody in the research community, including the authors of the catalog paper, considers this to be a groundbreaking or even a possibly groundbreaking result, or even a result worthy of any follow-up studies, despite the fact that the paper was published 4 years ago and there's been plenty of time for astronomers to follow up on this if they thought it actually had any merit. Aldebarium (talk) 02:19, 30 October 2024 (UTC)

Look, I understand the bias against large-scale surveys, but it would take more than just a declaration of "this data is garbage" to dismiss a quality assessment in the data based on the Appendix. Like I said, it just has to be verifiable, and this is not limited to having a plot of line fitting; an assessment of the quality of the spectral line and mass measurement is enough for inclusion in this list. It is no longer the job of Wiki to dismiss something as garbage even if the data shows a quality assessment otherwise; that would be directly contradicting the source - a job for other authors, and we just report it.

We can go on with the long debate of whether we should include results from large catalogues, but that would be equivalent to removing half of the entries in this list, and in the literature most BH mass measurements come from massive catalogues like this. Due to the nature of the subject, we should have a fairly lower stringency compared to, say, largest stars.

Side note: I find it funny that you consider the title of "largest black hole" consequential for astronomy, as I doubt serious astronomers would ever care more about a stick-measuring contest than the theoretical implications of massive black holes existing in general. SkyFlubbler (talk) 05:11, 30 October 2024 (UTC)