Federico Lelli (ESO)

Structure and Dynamics of Nearby Galaxies
When Sep 07, 2017 from 02:30 PM to 03:30 PM
What
  • Colloquium
Where SH Lecture Hall
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I will present recent results from the SPARC database: a sample of 175 late-type galaxies (spirals and irregulars) covering ~5 dex in luminosity and ~4 dex in surface brightness. Spitzer Photometry at 3.6 um provides the stellar mass distribution, while accurate HI/Halpha rotation curves trace the gravitational potential out to large radii. I will discuss several dynamical scaling laws, like the Baryonic Tully-Fisher Relation and the Radial Acceleration Relation. The latter relates the observed centripetal acceleration (gobs) to that expected from the baryonic distribution (gbar), implying a close link between baryons and dark matter in galaxies. The same relation is followed by ~2700 independent points at different radii in different galaxies. The observed scatter is remarkably small (30%) and largely driven by observational errors. Moreover, early-type galaxies and classical dwarf spheroidals seem to follow the same relation as late-type galaxies. This points to a "Natural Law" for galactic systems.