EDP Sciences
Free access
Issue
A&A
Volume 385, Number 2, April II 2002
Page(s) 431 - 453
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020166


A&A 385, 431-453 (2002)
DOI: 10.1051/0004-6361:20020166

Discrete dynamical classes for galaxy discs and the implication of a second generation of Tully-Fisher methods

D. F. Roscoe

School of Mathematics, Sheffield University, Sheffield, S3 7RH, UK

(Received 10 October 2001 / Accepted 24 January 2002)

Abstract
In Roscoe (1999a), it was described how the modelling of a small sample of optical rotation curves (ORCs) given by Rubin et al. (1980) with the power-law $V_{\rm rot}=AR^\alpha$, where where the parameters $(A,\alpha)$ vary between galaxies, raised the hypothesis that the parameter A (considered in the form $\ln A$) had a preference for certain discrete values. This specific hypothesis was tested in that paper against a sample of 900 spiral galaxy rotation curves measured by Mathewson et al. (1992), but folded by Persic & Salucci (1995), and was confirmed on this large sample with a conservatively estimated upper bound probability of 10-7 against it being a chance effect. In this paper, we begin by reviewing the earlier work, and then describe the analyses of three additional samples; the first of these, of 1200+ Southern sky ORCs, was published by Mathewson & Ford (1996), the second, of 497 Northern sky ORCs, is a composite sample provided by kind permission of Giovanelli & Haynes published in the sequence of papers Dale et al. (1997, 1998, 1999) and Dale & Uson (2000), whilst the third, of 305 Northern sky ORCs, was published by Courteau (1997). These analyses provide overwhelmingly compelling confirmation of what was already a powerful result. Apart from other considerations, the results lead directly to what can be described as a "second generation of Tully-Fisher methods". We give a brief discussion of the further implications of the result.


Key words: galaxies: general -- galaxies: fundamental parameters -- galaxies: spiral -- galaxies: evolution

SIMBAD Objects in preparation



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