Fredagskollokvium: Star Formation and Nuclear Activity: Dwarf Galaxies to Ultraluminous Infrared Galaxies

George Privon, University of Florida

George Privon,  Department of Astronomy, University of Florida (USA).

The stellar mass of star forming galaxies is thought to increase in a quasi-steady state, where the rate depends on the gas fraction and star formation efficiency, which evolve with redshift. Galaxy mergers can lead to more rapid growth while active galactic nuclei have been argued to play an important role in halting star formation. These processes are tied together through the multi-phase interstellar medium.

I will discuss programs exploring so-called "dense gas" tracers and the behavior of starbursts in merging dwarf galaxies. I will also describe a theoretical/modeling program to age-date galaxy mergers and constrain the initial conditions of their encounters. This use of multiwavelength tracers and hydrodynamic simulations probes galaxy evolution along axes of nuclear activity, redshift, gas fraction, and metallicity. From these studies I will show new results on identification of heavily obscured AGN and intriguing differences in how mergers affect the evolution of high gas fraction galaxies.

The image on the left is showing the observed, ongoing collision of two galaxies: NGC 5257 and NGC 5258 on top. The right panel is one output of a computer simulation which is matched to the the observations. Using the simulation we were able to show that the galaxies first collided about 230 million years ago and they will probably merge into a single remnant galaxy in another 1.2 billion years.
Credits: (left image) NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University). Right image: https://ui.adsabs.harvard.edu/abs/2013ApJ...771..120P/abstract

 

Publisert 14. sep. 2019 15:52 - Sist endret 10. des. 2019 14:45