SPACS Colloquium: “The Circumgalactic Medium: The Hidden Gaseous Envelope Surrounding Galaxies”

April 11, 2013 3pm
Art and Design Building Room 2003

Sanch Borthakur
University of Maryland

Galaxies are continually evolving. Their evolution depends on various factors such as how and when they accrete gas to produce stars, and expel metals and energy as a result of star formation. Most of these processes occur in the gaseous medium, also known as the circumgalactic medium (CGM), connecting the stellar body of the galaxies and the intergalactic medium (IGM). As such, the CGM provides clues about the processes regulating the cycle of matter and energy in and out of galaxies.

In this talk, I will give an overview of why studying the CGM is important and how the Cosmic Origin Spectrograph on the Hubble Space Telescope allows us to explore the connection between the properties of galaxies and their CGM. I will show that the CGM contains a significant baryonic reservoir of gas and metals. The CGM acts as a source of fuel as well as a sink for the products of star formation. Finally, I will talk about the processes by which the host galaxy can influence its CGM. In particular, I will show that starburst driven winds can ionize most of the CGM as far out as ten times the size of the host galaxy. The ionization of the CGM can interrupt the flow of cool gas into the galaxy, which in turn will dictate the galaxy’s ability to produce stars in the future.