Kinematics of the local universe. IV. Type dependence in the diameter Tully-Fisher relation and implications on the mass-luminosity structure.
Abstract
There is a type dependence in the diameter (Tully-Fisher) TF relation in the spiral galaxy range 1<=T<=8. This dependence appears as a zero-point shift from one type to another, while the slope seems to remain constant, close to 0.5 (inverse relation) as expected from our simple disc + bulge + dark halo model. The model also predicts well the amount of the shifts, when reasonable values of the mass-to-luminosity ratios of the disc and bulge components are used. A method to study the dark mass fraction β in different galaxy types, based on the model, is introduced. First applications suggest that in the range 2<=T<=7 the value of β=~0.5-0.8 within the radius gr_0_ that the TF-measurements refer to. There are also zero-point shifts in the B-magnitude TF-relation (the inverse slope ~0.1 according to our work), though smaller than in the diameter relation, as expected from the model. The found type dependencies will diminish the scatter in the TF-relations and facilitate their use in our KLUN programme for measuring the kinematics of the local galaxy universe.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1997
- Bibcode:
- 1997A&A...319..435T
- Keywords:
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- GALAXIES: SPIRAL;
- GALAXIES: PHOTOMETRY;
- GALAXIES: DISTANCES AND REDSHIFTS;
- GALAXIES: STRUCTURE;
- ASTRONOMICAL DATA BASES: MISCELLANEOUS