Talk:M–sigma relation

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Update of Slope and Restoration of Mathematical Derivation[edit]

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[edit]

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 (talkcontribs) 21:16, 6 September 2009 (UTC)