NRAO/Socorro Colloquium Series

Barry Madore

Cal Tech


What Is This Thing Called The Schmidt Law?


It is certainly reasonable that the gas supply in any given galaxy should play an important role in the process of star formation. No gas, no star formation. However, it is not clear just what causal role gas density, in specific, should play in controling or regulating the actual rate of star formation on any given scale within any given galaxy. The Schmidt Law takes the rate of star formation to be a power-law function of the gas density, and in recent years this parameterization has been incorporated into many galaxy evolution models as the controling recipe for star formation on global scales. I will explore the origins of this relation and attempt to reconcile the observational calibration(s) with the mathematical underpinnings. In doing so I will demonstrate that local versions of the Schmidt law cannot be self-consistently reconciled with global determinations without other fundamental data and assumptions. Moreover, I will show that the spatially-resolved Schmidt Law relations, as currently determined actually averages over important physical aspects of the star formation process that are key to understanding the role of gas in the cyclical process of star formation. New diagnostic diagrams for star formation rates will be presented. And, time permitting, I will introduce Typhoon, a newly deployed means of generating wide-field, high-resolution, multi-wavelength optical datacubes (having up to one billion pixels per galaxy) which will be extremely useful in detailing the rate of star formation in the optical for comparision with radio determinations of the gas distribution.






March 25, 2011
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: Juergen Ott