Talk:M–sigma relation

Update of Slope and Restoration of Mathematical Derivation
This page now gives the most recent determination of the slope, with error bars, from the 2005 Ferrarese & Ford review article (as cited). This value supersedes the earlier, Tremayne et al. value from 2002. Have also restored the mathematical derivation, and given a reference for it. Todlauer: please, if you are truly expert in this field as you say, contribute additional material to this page rather than just cut from it. If there is an other derivation of the relation that you prefer, than please add it here. But don't simply delete - that is not in the spirit of Wikipedia.132.77.4.129 (talk) 17:19, 29 December 2008 (UTC)

Ferrarese & Ford (2005) is more recent than Tremaine et al. (2002), but in no sense does it supersede it. Tremaine et al. (2002) looked very exhaustively at the issue of the correct slope, and its arguments have not been countered. Ferrarese & Ford (2005) is also not the most recent work. Plenty of other papers in 2006-8 recover the slope=4. The page as rewritten now is incorrect.

Concerning the "derivation of the slope," the source Faber-Jackson relationship, relation between M and M/L, have substantial scatter, much more than the m-sigma relationship. A backwards derivation of M-sigma if done properly would show large errors in the implied slope. This is not interesting.

Todlauer (talk) 23:10, 31 December 2008 (UTC)

Revision to Slope and Deletion of Mathematical Derivation
The M-sig relationship was discovered in 2000 by two groups, Ferrarese & Merritt, and the Nuker Team, of which I am a member. While there was disagreement at the time about the slope of the relationship, in Tremaine et al. (2002) we showed it to be about 4, and this has remained the preferred value since then. This slope has been remeasured by several other works after 2002, which can be cited in the main article if needed. The flat statment of the slope of 5 is incorrect as the current astronomical consensus.

The section showing a mathematical derivation of the M-sig relationship is not consistent with astronomical consensus, which more properly regards the M-sig relationship to be an empirical finding to be understood in the context of galaxy formation. Since the mathematics recovers an incorrect slope it is not useful in any case.

Lastly, it is incorrect that the relationship has no intrinsic scatter; again there are references to support this if required.

Todlauer (talk) 18:44, 25 December 2008 (UTC)

The section has been revised to show the most recent determination of the slope. The slope derivation, which remains incorrect has been deleted. —Preceding unsigned comment added by Todlauer (talk • contribs) 21:16, 6 September 2009 (UTC)

BBC Horizon 2013
I note that this article, much of which seems based on quite old papers, seemingly differs quite a bit from the 2013 BBC Horizon program about black holes at the centre of galaxies (its name may have been 'Inside a Black Hole', but I'm not sure about that; it was rebroadcast early this morning on BBC4). I'm not clear whether this is a problem with that programme or this article or both.

The program doesn't mention M-sigma, but has quite a bit about Magorrian (tho I think they spelled his name differently, McGorrian, I think). And they (in this case Magorrian talking to them, without contradiction) say the relationship is that the mass of the central Black Hole is about 0.5% of the mass of the galaxy (NOT the bulge), which is rather different from what we have here, and is a bit surprising given that the programme is 13 years after the publication of M-sigma in 2000.

They also attach great significance to the relationship, with various scientists (not just Magorrian) arguing that any such relationship (which would presumably also cover M-sigma) is surprising, and suggests that the central black hole, rather than being 'a mere ornament' (to quote one of them), may influence the formation of the galaxies, and thus ultimately help to create us. The possible mechanism suggested by them is that the powerful radiation from matter falling into the black hole would scatter matter further out in the galaxy, affecting how many stars get formed, etc. I wasn't particularly convinced (which is why I came here to try to check - our article currently seemingly never mentions any such claims) as I couldn't help suspecting that it might be the size of the big galaxy that caused the size of the little black hole, but that if you're a cart specialist you might hope to get more funds for cart research by promoting theories about carts pushing horses. But it would be nice to be able to find out here in Wikipedia whether that Horizon theory is now the scientific mainstream (as Horizon makes it appear) or merely dubious special pleading by a scientific fringe. Tlhslobus (talk) 04:24, 26 October 2016 (UTC)