The star formation rate and its variation in time are intimately
connected to the formation and evolution of galaxies from early
cosmological epochs to the present era. Ever since the pioneering work
of Schmidt a half-century ago there has been great interest in finding
an appropriate physical relation that would directly link some physical
property of interstellar gas with the rate of star formation in a
galaxy. In this talk I will discuss how observations of nearby Galactic
molecular clouds are now providing new insights into the nature of such
a physical link between the molecular ISM and the rate of star
formation in a galaxy. In particular, I will describe wide-field
infrared extinction mapping and Spitzer Space Telescope surveys that
together have produced the first reasonably complete accountings of
both star formation activity and molecular gas in the local Milky Way.
These new observations indicate that the star formation rates in local
molecular clouds are best correlated with the amount of dense gas that
these clouds contain above a specific high density threshold. This
correlation
appears to smoothly extend to galaxies of the nearby
universe and may represent the underlying physical relationship or law
that most directly connects star formation activity with the
interstellar gas both within our Milky Way and within and between
external galaxies. I will conclude the talk by showing how these
observations enable the unification of the various extragalactic
scaling relations (e.g., Kennicutt-Schmidt, Gao-Solomon) into a single
framework that can connect star formation on local and cosmological
scales.
March 23, 2012
11:00 am
Array Operations Center Auditorium
All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.
Local Host: Claire Chandler