1 / 29

The differential Tully-Fisher relation for spiral galaxies

The differential Tully-Fisher relation for spiral galaxies. Irina Yegorova SISSA, Trieste, Italy. Outline:. Observations of spiral galaxies The standard Tully-Fisher relation Differential Tully-Fisher relation. Evidence of dark matter comes from:. WMAP. X-Ray. gravitational lensing.

colt-pennington
Download Presentation

The differential Tully-Fisher relation for spiral galaxies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The differential Tully-Fisher relation for spiral galaxies Irina Yegorova SISSA, Trieste, Italy

  2. Outline: • Observations of spiral galaxies • The standard Tully-Fisher relation • Differential Tully-Fisher relation

  3. Evidence of dark matter comes from: WMAP X-Ray gravitational lensing rotation curves

  4. blue shift red shift

  5. The Tully-Fisher(TF) relation is an empirically established correlation between the luminosity L of a spiral galaxy and its rotational velocity V (Tully-Fisher, 1977)

  6. New method of determining Distances to galaxies R.B.Tully and J.R.Fisher, A&A, 54. 661-673, 1977

  7. TF-relation has two important applications: 1. It is used to obtain cosmological distances M=m - 5logD - 25 2. It can be used for studying the dynamical properties and the evolution of galaxies

  8. Physical basis of the TF-relation From the equation of centrifugal equilibrium we get: • V0 – representative velocity, M - total mass, • Rc – characteristic radius of luminous matter • - structural parameter depending on the shape of the mass distribution

  9. The first equation can be written in this form: This equation can be written in the form of the Tully-Fisher relation:

  10. Differential Tully-Fisher relation

  11. Vmax

  12. Samples: 1st sample: 967 spiral galaxies Mathewson (1992) 2nd sample: 304 spiral galaxies Courteau (1997) 86 galaxies selected for analysis 3 sample: 329 spiral galaxies Vogt (2004) 81 galaxies selected for analysis

  13. 1. Mathewson sample: R R/Ropt; bin=0.2 2. Courteau sample: R R/Rd; bin=0.2 3. Vogt sample: R R/Rd; bin=0.2 Ropt=3.2Rd, where R_d is the disk exponential length-scale, for Freeman (exponential) disk this corresponds to the 25 B-mag/arcsec^2 photometric radius.

  14. 1st sample: TF-relation for 967 galaxies

  15. 1st sample: TF-relation for 967 galaxies

  16. 2nd sample: TF-relation for 86 galaxies

  17. Slope of the TF-relation MB = ai + bilog V(Ri)

  18. Gap in the slopes of 2 samples: No dark matter k=0.1 for I band k=0.3 for R band function of the band The slope of TF-relation is related to k

  19. Physical meaning of the slope The slope of the TF-relation steadily rises with distance due to the fact that the fractional amount of the dark matter in galaxies changes with the radius.  increases with R decreases with L this has influence on the slope

  20. Scatter of the TF-relation

  21. TF-relation using Vmax slope=-7,579; scatter=0,328; number of galaxies=843 slope=-5.54; scatter=0.49; number of galaxies=83

  22. Main results: • We found the new method Differential TF relation. • 2. The slope decreases monotonically with the distance, while • the scatter increases with distance. This implies the presence • of a non luminous mass component (DM) whose dynamical • importance, with respect to the stellar disk (baryonic matter) • increases with radius. • 3. We found small scatter in the TF-relation. This implies • that galaxies have similar physical characteristics. • 4. Minimum of the scatter 0.15 (1st sample), 0.24 (2nd sample), • 0.29 (3 sample) at 2.2R/Rd at the position of the maximum disk contribution • We are planning to do mass modeling for these galaxies to • reproduce the observable slope and scatter in the TF-relation

  23. Work in progress

More Related