Talk:List of most massive black holes/Archive 1

Archive 1

Largest or most massive?

It really creates me confusion. Yes, more massive black holes are larger, however, why are they large? Because of their mass.

However it confuses me. Largest or most massive? ==Johndric Valdez (talk) 10:05, 16 November 2013 (UTC)==

The size of a black hole singularity is always the same, infinitesimal, the size of the event horizon depends solely on the mass of the black hole. So "most massive" works better, as someone might think it was about the volume of the singularity, which does not change with anything. However, you could consider adding the size of the event horizon to the table. -- 65.94.171.206 (talk) 01:11, 4 May 2014 (UTC)

Why was this article created?

To be honest, I created this article to have updates about black holes, like the list of largest known stars page. Such news are spreading to the Internet. Some of them are:

• Some saying M87 has largest black hole

• Some saying NGC 1277, others OJ 287

What is it really? So I created this page. For news in the Internet with false issues to be stopped.

The final thing before I created this is that some news say NGC 4889 as largest but NGC 1277 is 2nd. I come up here to show that NGC 1277 is really 5th and the 2nd place really belongs to the Phoenix Cluster, through which the data is long abandoned.

So that's it. Created for people to be informed. ==Johndric Valdez (talk) 10:05, 16 November 2013 (UTC)==

Just heere to say that I appreciate it. RhinoMind (talk) 12:57, 28 May 2015 (UTC)

Requested move 18 May 2015

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: No consensus. There seem to be enough questions marks at the moment, and a body of opposition, so I suggest some further discussion on the way forward. (non-admin closure)  — Amakuru (talk) 10:39, 3 June 2015 (UTC)

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List of most massive black holes → List of black holes by mass – Includes a more comprehensive range of masses (intermediate and stellar mass) and makes a better comparison SkyFlubbler ^(talk) 11:07, 18 May 2015 (UTC)

• Support. Khestwol (talk) 15:30, 18 May 2015 (UTC)
• Oppose there should be no unrestricted list of black holes by mass. The list should be restricted to the most massive known. This should not be some random selection of black holes. -- 65.94.43.89 (talk) 20:41, 18 May 2015 (UTC)
• Support - Ninney (talk) 20:59, 18 May 2015 (UTC)
• Support. The proposed title is more internally coherent. As it is the title might even be read: List of most of the black holes in the Universe. A more grammatically accurate version of the current title might be List of the most massive black holes that have been discovered to date. The proposed title is better. GregKaye 21:24, 18 May 2015 (UTC)
• Oppose Conditional support. If and only if there is a high mass-cuttoff, similar to the current page, per 65.94.43.89's oppose.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  14:35, 19 May 2015 (UTC)

Just slightly relax the mass-cutoff of the current page instead.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  14:40, 19 May 2015 (UTC)

My plan is that the black holes list table are colored, such as the way as List of most luminous stars, red or pinkish for supermassive, yellow or gold for intermediate and light blue for stellar mass. Reason is some black holes have estimates that cross the boundary between intermediate and supermassive, stellar and intermediate, which case they could be green or orange.

There's no problem for sources; there are hundreds (even thousands, maybe) of citations of astronomers in arXiv about black hole masses, so it is unlikely to occur a problem similar to the List of largest known galaxies. What makes me have a second opinion is that such a list would be incredibly huge. SkyFlubbler ^(talk) 04:03, 19 May 2015 (UTC)

SkyFlubbler this is not something that I have personally dealt with but I would suggest perhaps taking a look at Help:List, Wikipedia:Naming conventions (long lists)#Long (split) list naming recommendations, Wikipedia:Manual of Style/Lists and similar to see if there are relevant routes forward. At present the list has ~130 items. Also not all lists need to be complete. See: List of country subdivisions by area. GregKaye 06:27, 19 May 2015 (UTC)

• Support There's no need to have the quantifiers "...in the Universe" or "...that have been discovered to date" as that goes without saying. The lead covers the inclusion criteria (IE known black holes in the universe). Lugnuts ^{Dick Laurent is dead} 07:11, 19 May 2015 (UTC)

The list currently has 114 entries, but I still have five papers here with black hole estimates of 71 BL Lac objects, 35 Seyfert galaxies, 42 quasars, 28 BCGs and 7 other galaxies from an independent study, totalling almost 300 entries. This doesn't include another few thousand intermediate and stellar mass entries. SkyFlubbler ^(talk) 14:17, 19 May 2015 (UTC)

Be careful of wading into WP:NASTRO.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  14:29, 19 May 2015 (UTC)

I will. These entries are just on the list, with mass quoted and reference for that mass. What I really like about this list is that black holes have a far more citations than the largest stars, and even some candidates in the largest stars list cite references that is not exact.

I assure that only those black holes in the references will be reported. I will study entries on List of black holes. Lots of them are bluelinked at the very least. SkyFlubbler ^(talk) 17:00, 19 May 2015 (UTC)

There've been plenty of successful AfDs on astronomical objects which have been in a paper. Being in a paper does not equal notability per se. Just an fyi.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  17:17, 19 May 2015 (UTC)

Well, this is a list, and lots of news feeds and press releases report black holes. This would be a pretty fair claim, in fact, the Jan. 25 press release of ESO links this list. SkyFlubbler ^(talk) 17:36, 19 May 2015 (UTC)

• Comment It may be premature to pose this as a requested move. It seems to be a question about changing the purpose of the article. The lead paragraphs have been changed to state: This list contains all black holes with precisely known masses. Is this what the editors want here? Should this be a list of every black hole with a measured mass in the literature, including those that don't meet the criteria for a notable astronomical object?

Massive stars are rare. Massive black holes aren't. Now that many black hole masses are being determined, is this the best type of list to have? Maybe it should become a list of masses of those objects, but only those notable enough to have an article.

To be notable an astronomical object has to have been analyzed in several sources, not just listed, and not just picked up in multiple newspapers at the time it was discovered. StarryGrandma (talk) 17:51, 19 May 2015 (UTC)

I intend to list here all the entries that can be found, 1 million solar masses or greater, notable or not. Maybe that's the reason I would like to move it, since the current title gives the essence of "only the biggest black holes, ordered by mass" with the latter being "all known black holes, ordered by mass". The latter also portrays "black holes and probable candidates". Changing the heading would give the topic. SkyFlubbler ^(talk) 19:35, 19 May 2015 (UTC)

That should bave been a new article instead of repurposing this article. A list of most massive black holes would be succint and clearly defined (a top 100, or something with a low mass cut-off). A complete list of black holes with known masses should have been done as a separate listing. That listing should be sortable by right ascension, location, constellation, etc. -- 65.94.43.89 (talk) 06:17, 20 May 2015 (UTC)

• Oppose; the new title would have to include every black hole in existence, which simply won't do due to the vast number known or theorized. Instead, what we can do is have a section in this article for the largest intermediate-mass black holes and another section for stellar black holes. StringTheory11 (t • c) 16:59, 20 May 2015 (UTC)

So you mean, a comparison? And by you said "theorized", I think we must change the lead sentence to black holes and also probable candidates. SkyFlubbler ^(talk) 09:41, 21 May 2015 (UTC)

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The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Event horizon radii?

Should the event horizon radius of each black hole be shown? I got approximations using the Schwarzschild radius formula and made an example of what I mean: http://i.imgur.com/Tg8UFZK.png

This would probably help people understand the size of the event horizon and compare it to the Sun. Should I go through with this or is it unnecessary? --Are you freaking kidding me (talk) 01:50, 24 November 2015 (UTC)

That would be taking up the space. This is not like the list of largest known stars article, as you can see, the numbers are in billions. SkyFlubbler ^(talk) —Preceding undated comment added 09:50, 19 December 2015 (UTC)

I like the idea of adding the event horizon radii of the black holes to the table. I think you should go through with this. Multiverse Guy (talk) 22:03, 21 December 2015 (UTC)

NGC 1600

Black hole at the centre of NGC 1600 has been found to be 17 billion solar masses. Add or more verification required? --82.28.205.130 (talk) 01:34, 7 April 2016 (UTC)

More here! --2001:630:12:2E20:2093:B30:743A:A2B3 (talk) 16:35, 8 April 2016 (UTC)

Article title is ambiguous

The article title ("List of most massive black holes") is ambiguous because "most" could describe either the mass or the number of the black holes. I presume it is intended to be the former. (If it was the latter, then once the list was complete the article could be renamed "List of all massive black holes".) To remove the ambiguity, should the article be renamed "List of the most massive black holes", as in the article's opening phrase? I think this would be better than "List of most-massive black holes". Nurg (talk) 08:44, 19 May 2018 (UTC)

The word "massive" by itself is meaningless, requiring context to have any definition. Since it requires "most" to define the scale, there is no ambiguity in English. By the standards of humans, any black hole is massive, so the latter definition above would require it to be a list of most black holes.Kentpollard (talk) 14:53, 19 May 2018 (UTC)

ULAS J1342+0928's outrageous mass

Well here i go. In the list, someone put a mass of 400 trillion solar masses for ULAS J1342+0928. That's its luminosity! Please remove this, i really think that should NOT be there. - Gurren Lagann, a common wiki visitor and small comparison youtuber. 170.231.113.182 (talk) 14:25, 8 September 2018 (UTC)

 Done Gulumeemee (talk) 06:52, 9 September 2018 (UTC)

Semi-protected edit request on 18 May 2019

122.163.94.162 (talk) 09:29, 18 May 2019 (UTC)

The biggest most super ultra massive black hole is SDSS J140821.67+025733.2 at 198 billion solar massess and it is 17 billion light years away from Earth.

 Not done: please provide reliable sources that support the change you want to be made. Primefac (talk) 11:43, 18 May 2019 (UTC)

Semi-protected edit request on 13 September 2019

19.6 x 10^10 solar masses)

2001:B07:644E:4307:408E:B972:DE15:FE07 (talk) 03:49, 13 September 2019 (UTC)

 Not done. The YouTube video uses Wikipedia as a reference, and Quora is just a asking-questions board. Neither is reliable. Primefac (talk) 14:07, 13 September 2019 (UTC)

References

Semi-protected edit request on 19 August 2019

The third on the list of most massive black holes in the universe should now be Holm 15A, estimated at 40 billion solar masses. Here is the reference, K. Mehrgan et al. 2019. A 40-billion solar mass black hole in the extreme core of Holm 15A, the central galaxy of Abell 85. Astrophysical Journal, in press; arXiv: 1907.10608 . 139.52.21.127 (talk) 20:37, 19 August 2019 (UTC)

Done. SkyFlubbler ^(talk) 23:33, 19 September 2019 (UTC)

Maths check

The reference for SDSS J102325.31+514251.0 gives $\log M_{BH}=9.8M_{\odot }$. Isn't that along the lines of 6.3 billion solar masses, not 33 billion? Primefac (talk) 20:56, 28 September 2015 (UTC)

Sorry for the late reply.

The paper at the reference (https://arxiv.org/pdf/1412.2438.pdf) cites on the table at page 27 a logarithmic value entry at J102325.31+514251.0 to be 10.52 ± 0.08 M. This is equal at least to 33.11 billion solar mass, give or take 6 billion. SkyFlubbler ^(talk) 23:54, 10 October 2019 (UTC)

Semi-protected edit request on 8 December 2019

add to list SDSSJ140821.67☆025733.2 172.103.235.104 (talk) 12:33, 8 December 2019 (UTC)

 Not done: please provide reliable sources that support the change you want to be made. Primefac (talk) 13:21, 8 December 2019 (UTC)

Semi-protected edit request on 4 January 2020

— Preceding unsigned comment added by 2a00:23c6:eb8b:bb01:2493:16ff:c5b1:8977 (talk) 15:58, 4 January 2020 (UTC)

 Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Majavah ^(t/c) 17:43, 4 January 2020 (UTC)

Semi-protected edit request on 6 April 2020

216.11.189.203 (talk) 18:59, 6 April 2020 (UTC)

Add SDSS J140821.67+025733.2 it has 196,000,000,000 SM

Emphatic no on this. This is not a correct or reliable mass measurement. It's from a catalog entry based on automated measurements that went wrong on a peculiar spectrum. We've been through this repeatedly before and an article on this object was deleted a couple of years ago because it didn't meet notability criteria. Aldebarium (talk) 19:14, 6 April 2020 (UTC)

Black hole in the news

Isn't their a black hole called J1417 or something in the news that is 30 billion solar masses? Can it be added? (I would add it myself but I forgot the name of the thing in question).

Thanks!PNSMurthy (talk) 05:36, 16 July 2020 (UTC)

Error

Shouldn't they giv error bars on the mass of TON 618? What ar the confidence intervals on its mass? I would like to know, ar scientists fairly confident that its mass actually exceeds, say, 5 × 10¹⁰ solar masses?--Solomonfromfinland (talk) 13:55, 25 August 2020 (UTC)

The paper by Shemmer et al. on this link [[1]] shows no error bars for TON 618. The logarithmic mass value being cited in the table at page 6 is 10.82. So 10^10.82 = 66 billion solar masses. SkyFlubbler (talk) 13:47, 28 November 2020 (UTC)

Revisiting the old monster: SDSS J140821.67+025733.2

I know there has been a discussion regarding this object, with a consensus reaching that it should be deleted way back.

However, there has been another paper by Zu et al. (see here: https://arxiv.org/abs/2007.03222 ) as recent as July 2020 that cites this object as having 196 billion solar mass on page 2. The reference cited goes back to the original paper by Kormendy Kozlowski et al. that doesn't cite this quasar in particular. However, it has been mentioned in the DOI of his paper at The Astrophysical Journal here: https://iopscience.iop.org/article/10.3847/1538-4365/228/1/9 where he specifically mentions this quasar at section 3: Discussion.

"The most massive appears to be SDSS J140821.67+025733.2 at z = 2.055, but it is about 10 times less luminous than the preceding two objects. It has an estimated BH mass of 196 billion solar masses."

One of the reasons why this article was deleted in the past discussion was because Kormendy Kozlowski et al did not mention this in his paper (the main PDF of the reference). And I was opposed to having this on the list for the same reason. But it was only yesterday when I discovered this DOI (and I felt bad for doing so) and presumably because this has been cited again by another paper in the scientific literature, more than just being a catalog entry, do I began to think that maybe this quasar and the ridiculous ~200 billion solar mass value is recognized at least in the scientific community.

I would want to discuss a few points here though.

Should we accept the value being given by Kormendy Kozlowski? I honestly think that this value is ridiculous (a bigger hype than the 2007 VY Canis Majoris size) and it is so, so far away from the values of the other entries (10x the value of others). I am not here to question Kormendy and his science though. This quasar was not mentioned by Kormendy Kozlowski in his DOI to be a probable spurious measurement or having any sort of irregularity (but I still believe it does). Should we accept this paper on the basis that it is recognized by another reference and it is more than just a catalog entry? I would be willing to submit though if this quasar was again included on this list (I am not the same stupid child years ago, duh.), but I would just want to raise this topic again so some other guys here can take another pinch of salt regarding this issue.

Regards! SkyFlubbler (talk) 15:18, 13 December 2020 (UTC) (Corrected SkyFlubbler (talk) 05:23, 18 December 2020 (UTC))

By the way, if one can look upon this data and see for yourself if it is acceptable as an addition for this, I would be happy.

https://iopscience.iop.org/0067-0049/228/1/9/suppdata/apjsaa5504t1_mrt.txt

Be warned though, this page is monstrous with 280,000 entries. If it is added, maybe we can just select a few with comparatively high masses. SkyFlubbler (talk) 17:21, 13 December 2020 (UTC)

Since no one has posted a reply here yet, in spite of me bringing this as far as to the WP:AST, I decided to submit a draft about this quasar, which somehow got accepted in the review in here: SDSS J140821.67+025733.2. I am contacting the person who made the change since this subject is still pending in my submitted deletion review

If somehow this was accepted in the review, I will be putting this candidate in the list with the absurdly ridiculous mass estimate - in good faith I hope - on the basis of the following:

1. The Articles for Deletion discussion has not discussed the DOI of the main source which specifically mentions this quasar and the mass estimate.

2. The other paper mentioning this quasar, making me think that this was somehow accepted on the broader scheme of things.

3. If per notability reasons we should not put this quasar in the list, we can also have an extensive discussion about the further ones that we can remove. If not, and somehow the Kozlowski (sorry, not Kormendy, how stupid I am) paper was accepted, this would certainly be on the list, along with the others in the data. We can go hand-in-hand and discuss the standards of which entries we can put in the list. Because Kozlowski's data is massive - it has 280,000 entries and I can barely even load it here in my PC.

If you have any questions, or if you think I made a huge misconduct (which I hopefully not since I'm quite stressed a bit), contact me in my talk page. Regards! SkyFlubbler (talk) 06:25, 18 December 2020 (UTC)

"see for yourself if it is acceptable" - that sounds very much like OR to me. What criteria are you suggesting people use to make such a decision? Personally, the only measurements I would trust for a list like this are those taken from direct measurements of the stellar velocity dispersion of the very inner most region (as done for Sgr A* and M87, for example). That would make a pretty short list, but at least it would be accurate. Most other estimates, especially ones for very distant quasars, are best used in bulk for looking at classes of objects, and are not as trustworthy for individual sources (scatter of 0.5-1 dex often, with multiple levels of assumptions and inference required). - Parejkoj (talk) 23:45, 19 December 2020 (UTC)

If we are only taking measurements based on stellar velocity, then that would be a ridiculously short list. I have no problems with using only stellar velocity dispersion though, but it would only be a few handful of galaxies and would delete 99% of everything here. Maybe I suggest to also include the methods being used to take the masses - a new column besides the notes? SkyFlubbler (talk) 04:55, 21 December 2020 (UTC)

Replying again since I just removed it from here and nominated the page for deletion. Zu 2020 is absolutely not a useable source for a discussion of this object's mass or notability: they just took the catalog value and ran with it. If I'd been a reviewer on that paper, I would have objected immediately. If you want to make this list in any way coherent, it does need a column describing the method of the measurement with a citation to the relevant paper. - Parejkoj (talk) 22:30, 30 December 2020 (UTC)

Please stop cherry-picking the largest estimates from each paper.

Today I noticed that a new "largest" known black hole was added, and so I checked the paper(s). I noticed that the value on the list was the largest of three, with the two other ones being nowhere to be seen.

So to anyone who may add a new black hole to the list, don't just add the largest value from the paper(s), use both the smallest and largest as a range. Nussun05 (talk) 14:55, 12 September 2021 (UTC)

Holmberg 15A

I just added Holmberg 15A as the most massive black hole known, but discovered therafter it was already in the list in a lower position. The page on Holmberg 15A cites the same paper, yet, two different masses are given on that page (170 billion solar massses) and in this list (10 billion solar masses). — Preceding unsigned comment added by 50.21.132.155 (talk) 11:28, 26 July 2015 (UTC)

Semi-protected edit request on 7 Aug 2019

The paper gives more accurate Holmberg 15A mass estimate of 40 billion solar masses using surrounding stellar kinematics method. — Preceding unsigned comment added by Strelec A (talk • contribs) 18:53, 7 August 2019 (UTC)

Semi-protected edit request on 20 April 2022

let me edit it i wanna add sagourtirus a 12.118.112.254 (talk) 13:45, 20 April 2022 (UTC)

yes 12.118.112.254 (talk) 13:47, 20 April 2022 (UTC)

 Already done It is already on the list. ScottishFinnishRadish (talk) 13:59, 20 April 2022 (UTC)

MS 0735.6+7421

Working out the error value of 10^10.71 +0.46 for MS 0735.6+7421 gives an error value larger than the mass itself. Is the working correct because that seems off? Faren29 (talk) 23:22, 1 June 2022 (UTC)

Naming supermassive black holes at the cores of galaxies

Should we add an asterisk to all supermassive black holes at the centre of galaxies to distinguish them from their host galaxies? For example, Messier 87's central black hole has been called Messier 87* and Holmberg 15A's central black hole has been called Holmberg 15A*. Faren29 (talk) 14:43, 11 June 2022 (UTC)

No- this is not standard astronomical terminology for supermassive black holes in general. The asterisk originally was used in the context of Sgr A* to refer to a specific radio source in the Sgr A region, long before it was conclusively known to be a black hole. The name Sgr A* is now commonly used to refer to the black hole, but we should be careful to distinguish the radio source (radio emission from the accretion flow) from the black hole itself. The same applies to M87* where the asterisk has been used by analogy to Sgr A* to refer to the radio source, and has come to be somewhat synonymous with the black hole, but it's important to keep the distinction in mind. Wikipedia articles should not make an assumption that this naming convention for radio sources applies to supermassive black holes in general. Aldebarium (talk) 16:01, 11 June 2022 (UTC)

Help

This is a reference from 2011 giving black hole estimates of SDSS quasars: https://cfn-live-content-bucket-iop-org.s3.amazonaws.com/journals/0067-0049/194/2/42/revision1/apjs390188t3_mrt.txt?AWSAccessKeyId=AKIAYDKQL6LTV7YY2HIK&Expires=1656111700&Signature=4DftlYJcdNKby3xZSXq/fN85Hqo=

As you can see, the list is pretty damn massive. Simply too much for my pathetic setup to load. If anybody out there who has a computer that is not a potato, I hope you can take your time to get on this one. We might get some pretty exciting candidates, perhaps? SkyFlubbler (talk) 23:21, 17 June 2022 (UTC)

Personal note: Good luck trying to read the list. Keep a eye out for the right numbers. SkyFlubbler (talk) 23:38, 17 June 2022 (UTC)

Someone needs to put this into a table and order by mass. I checked through this quickly and the highest mass present on the table is 15.5 billion solar masses. Faren29 (talk) 17:49, 18 June 2022 (UTC)

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)