Talk:Active galactic nucleus

message: There was a question in the article from At18; I moved it here:
:I put infrared and radio galaxies here too, is it the right place?
Certainly better here than nowhere, work in progress ... -- looxix 18:58 Apr 18, 2003 (UTC)
: On the above point, I think Radio galaxy should have it's own article, instead of being redirected to Active galaxy, since the two terms are not interchangable. Radio galaxies are a sub-category (as are quasars, blazars, Bl Lacs, etc..). Unless there's any objections, I can begin work on a Radio Galaxy page and un-redirect once it's reached a semi-mature status. Privong 18:42, 21 Apr 2005 (UTC)
replies: text: OK, it's there now... Mhardcastle 23:41, 5 February 2006 (UTC)
thread_title:  Radio galaxies? 

message: Starburst galaxies aren't active galaxies (as the definition at the top of the article shows; they're just normal galaxies with a large amount of star formation).
Starbursts should really have their own entry, but I don't have time to do it now: I've just removed the misleading comments from the active galaxy page, and tidied it up. -- mjh, some time ago
* Starburst galaxies are active galaxies, they just don't have AGN. This article should be at Active galactic nuclei instead.  Don't you remember all the theories on how starburst galaxies could account for AGN type galaxies? They are active, but not single sourced, and they are bright, and spectacular, like AGN galaxies. 132.205.45.110 05:46, 6 Dec 2004 (UTC)
thread_title:  Starburst galaxies 

message: I'm no expert but should "An active galaxy is a galaxy where a significant fraction of the energy output is not emitted by the normal components of a galaxy: stars, dust and interstellar gas." be clarified to a numerical proportion? Or is this impossible. A comparison, to a regular galaxy if possible, might help non-experts like me understand this better. Grox 10:07, 13 Feb 2005 (UTC)
replies: text: There isn't a concrete numerical factor, but the AGN will generally outshine the host galaxy by ~1000x. Privong 18:22, 21 Apr 2005 (UTC)

text: This is only true for the most powerful AGN. Mhardcastle 20:43, 1 February 2006 (UTC)
thread_title:  Clarification 

message: As this stands it not only is factually wrong in several respects but duplicates (or in some cases contradicts) what's already there under `Optical spectra'. I'm tempted to delete the whole lot unless it gets a lot better before I look at this again Mhardcastle 18:54, 24 October 2006 (UTC)
replies: text: Go for it. I was just attempting to clean up what was already there. The Seyfert definitions were reversed before I made the edits. Perhaps it might be better to remove the optical spectra section and instead include that in the 'Types of active galaxies' section. That might be a more logical way to approach it? Privong 11:49, 25 October 2006 (UTC)
thread_title:  New text under `Types of active galaxy' 

message: This article lacks a section on Low-Ionization Nuclear Emission-line Region (LINER)-type galaxies, which are supposedly the most common type of active nuclei galaxy. Any interest? Thanks. — RJH (talk) 20:03, 4 December 2006 (UTC)
thread_title:  Low-Ionization Nuclear Emission-line Region (LINER) 

message: Once I started editing this, I couldn't stop. Hope readers approve of the results. It could do with some diagrams and some more references in places. I think it's an improvement on the original, though. I'm afraid it still doesn't mention LINERs, but they should have their own article, which should then be linked here. I'm not enough of an expert on LINERs to write one from scratch. Mhardcastle 22:02, 24 December 2006 (UTC)
replies: text: I added a "see also" link. -- Beland (talk) 02:10, 24 November 2007 (UTC)
thread_title:  Complete rewrite 

message: Is H II nucleus a type of AGN?  I notice it in this paper: [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997ApJS..112..315H A SEARCH FOR "DWARF" SEYFERT NUCLEI. III. SPECTROSCOPIC PARAMETERS AND
PROPERTIES OF THE HOST GALAXIES] These are not covered in the article presently. WilliamKF 01:59, 26 February 2007 (UTC)
replies: text: Looks to me as though they are using 'HII nucleus' to mean 'nucleus where the spectrum is consistent with that of an HII region', i.e. a source whose emission lines are powered by star formation. Look at the start of S3. Mhardcastle 08:53, 26 February 2007 (UTC)
thread_title:  H II nucleus is an AGN? 

message: The statement in the article about unknown explanations for accretition disc jet properties should be amended. Reva Kay Williams, University of Florida, has provided an explanation for the immense power and features of relativistic jets.  She developed a proof of Roger Penrose's mechanism from gravitomagnetism for extracting energy and momentum from rotating Kerr black holes.  Her model shows that the Lense-Thirring effect (frame dragging) produced by a spinning black hole can account for the observed high energies and luminosities of quasars and active galactic nuclei; the collimated jets about the polar axis; and asymmetrical jets (relative to the orbital plane).  They are inherent properties of Kerr black holes.  Those properties can be derived without resorting to magnetohydrodynamics.  
* Gariel, J.; MacCallum, M. A. H.; Marcilhacy, G.; Santos, N. O. (2007, February 23).  Kerr geodesics, the Penrose process and jet collimation by a black hole.  Preprint arXiv: gr-qc/0702123v1.
*Penrose, R. (1969).  Gravitational collapse: The role of general relativity.  Nuovo Cimento Rivista, Numero Speciale 1, 252-276.
*Williams, R. K. (1995, May 15).  Extracting x rays, Ύ rays, and relativistic e-e+ pairs from supermassive Kerr black holes using the Penrose mechanism.  Physical Review, 51(10), 5387-5427.
*Williams, R. K. (2001, October 15).  Collimated energy-momentum extraction from rotating black holes in quasars and microquasars using the Penrose mechanism.  AIP Conference Proceedings, 586, 448-453.
*Williams, R. K. (2004, August 20).  Collimated escaping votical polar e-e+ jets intrinsically produced by rotating black holes and Penrose processes.  The Astrophysical Journal, 611, 952-963.
*Williams, R. K. (2005).  Gravitomagnetic field and Penrose scattering processes.  Annals of the New York Academy of Sciences, 1045, 232-245.
I believe some of the above should be considered for incorporation with this article.  Tcisco 06:36, 21 April 2007 (UTC)
replies: text: As the article makes clear at present, the problem is not that there are no models for jet generation -- the problem is that there are many models and no observational way to distinguish between them. I don't see anything in the references above that would require that statement to be changed. An article that presented all the models and the arguments for and against would be interesting, but this article just needs to summarize the situation, and the summary at the moment is accurate (unlike the grossly inaccurate state of e.g. relativistic jet). Mhardcastle 07:29, 21 April 2007 (UTC)
thread_title:  Effective Gravitomagnetic Explanation for Jets 

message: The stub content of Galaxy AGN classification is a subset of what is contained in `Types of active galaxy'.  No content needs to be merged; I just am not too sure about dealing with pages that link to the redundant stub. 139.169.220.12 (talk) 18:41, 8 September 2008 (UTC)
replies: text: Redirect to the relevant part of this article? Mhardcastle (talk) 19:43, 8 September 2008 (UTC)

text: Agree - merge and add redirect. Actually I don't think there is much worth merging Codec (talk) 06:57, 9 September 2008 (UTC)
thread_title:  Merger proposal 

message: Wouldn't be useful an image like this? I was planning on creating something like that myself, but it won't be fantastic. Does anyone know a good free image? In case not, what should I highlight in the image apart from the obvious (accretion disk and jets)? I was thinking about removing the whole viewing angle story, since it already has its section and image. 
What do you all think?
Heinerj (talk) 22:51, 15 May 2015 (UTC)
replies: text: I've been waiting for someone to create a newer version of that plot for a long time: there are a few different versions of that, all made in the mid/late 90s. It's not inaccurate, but it certainly could be made nicer. - Parejkoj (talk) 05:50, 16 May 2015 (UTC)
replies: text: What are you thinking about? What should be included\excluded or could be better? Heinerj (talk) 20:43, 17 May 2015 (UTC)
thread_title:  Unified model image 

message: The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion:
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Participate in the deletion discussion at the . —Community Tech bot (talk) 03:45, 26 February 2021 (UTC)
thread_title:  A Commons file used on this page or its Wikidata item has been nominated for deletion 

message: This article does not mention the N galaxy, which was a frequently used classification for objects between a Seyfert an a QSO. For example:
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This historical term is mentioned in other encyclopedias, so I think it would make sense to cover that here. Praemonitus (talk) 21:40, 25 January 2022 (UTC)
replies: text: It would be useful to add a brief definition for historical completeness, but this term is not used at all in research literature any more- it is pretty much an obsolete classification, so there’s no need to include more than a sentence or so about it. And, any description of it should make clear that this classification isn’t used any more. Aldebarium (talk) 23:50, 25 January 2022 (UTC)
replies: text:  This would probably be appropriate for the history section then. I added a brief definition to the glossary so at least it's covered somewhere: N galaxy. Praemonitus (talk) 14:43, 26 January 2022 (UTC)
thread_title:  N galaxy 

message: I added a new section "New development" after the publishing in AphJ in 2022, https://iopscience.iop.org/article/10.3847/1538-4365/ac5b64  of a new discovery about SBMH that requires a change in the unified model of AGNs (cf. Padonani and Urry, 1995 and its updates) -- Luxorion
: That is way too much detail and undue weight to add to this WP article about one recently published paper: see WP:UNDUE. This should absolutely not be a whole section in the article. Recommend cutting this text back to just a sentence or two describing the main conclusions, and including it in the unification section without it being a separate section or even a separate subsection. Aldebarium (talk) 14:53, 4 August 2022 (UTC)
replies: text: WP:RECENT definitely applies here. It's too early for the community to have discussed it. You also added quite a few unsourced quotes, which I assume are from secondary sources. This should be a paragraph in the "Criticism of the radio-quiet unification" section, with some secondary sources (not just press releases) as well. - Parejkoj (talk) 18:43, 4 August 2022 (UTC)

text: I just tried to rework it, also citing Ricci 2017. Unfortunately, I've been out of touch with this part of the field for a while, so I'm sure it needs some work. The whole "criticism" section really should be reworked, since I don't think it's exactly a "AGN unification was wrong" and more "there are more aspects to it that we've identified". - Parejkoj (talk) 19:14, 4 August 2022 (UTC)
replies: text:  Agreed - the whole "criticisim of radio-quiet unification" section needs to be rewritten and retitled, to be at a more appropriate level of detail for the overall article. Aldebarium (talk) 19:33, 4 August 2022 (UTC)
thread_title:  Nex developments around the unified model of AGNs 

message: This goes with the discussion at Wikipedia talk:WikiProject Astronomy#Quasar tsunami (red link). Can we add a possible section in here explaining AGN outbursts? There is a lot of discussion about this in astrophysics circles over the last decade, detailing bubbles, gas sloshing, and cavities (reminiscent of Ophiuchus). SkyFlubbler (talk) 19:06, 11 November 2022 (UTC)
thread_title:  Regarding AGN outbursts 

message: The section "Observational characteristics" has no references and is almost exclusively model results. I will replace it with a sourced section. Johnjbarton (talk) 02:41, 10 March 2024 (UTC)
thread_title:  Observational characteristics?