Fundamentals of Gaseous Halos

Coordinators: Cameron Hummels, Ben Oppenheimer, Mark Voit, and Jess Werk

This program will be held online. Those interested should apply using the link in the sidebar. Please ignore the application deadline.

Fundamentals of Gaseous Halos (Jan 11 - Mar 5). All program events begin 8 AM PDT, Monday through Friday.

Program Logistics

All program announcements, and most discussions will happen via the KITP-sponsored Slack. All participants should join using thislinkto KITP Slack. At minimum, join the #halo21-general and #halo21-announcements channels, and feel free to join other #halo21 channels of interest.

Plenary Sessions, described below, will happen over Zoom, with links provided each week by KITP via Slack and email.

Program Description

Gas in the halos of galaxies dominates the universe's baryon budget, traces its dark-matter potential wells, and supplies the fuel for star formation. Circumgalactic gas has also long been suspected to regulate galaxy evolution by warehousing the byproducts of galactic metabolism and recycling them through galaxies. Many elementary questions about the circumgalactic medium (CGM) remain unanswered because it has been so difficult to detect, but within the last decade observations have begun to reveal its contents, dynamics, and thermal structure. Those measurements, in turn, are revolutionizing our theoretical understanding of how galaxies obtain fresh gas for star formation, how supernova explosions collectively drive powerful outflows from galaxies, how thermal instability and precipitation regulate the structure of the CGM, and how feedback processes may suppress the flow of gas into the galaxy.

This program will bring together specialists from the numerous, disparate communities of observers and theorists whose research intersects with the CGM. One of the primary goals will be to assemble a coherent theoretical framework for interpreting the diverse array of CGM observations that are now becoming available.

Program Themes

Each week of the program will focus on a particular motivating question, as listed below.

A detailed schedule for each week will be posted by Friday of the preceding week, and

probably earlier.

  • Week 1 (Jan 11-15): How do gaseous halos depend on halo mass?
  • Week 2 (Jan 19*-22): Why are gaseous halos often multiphase?
  • Week 3 (Jan 25-28): What roles do non-thermal components play?
  • Week 4 (Feb 1-5): What does the Milky Way tell us?
  • Week 5 (Feb 8-12): How does gas flow out of galaxies?
  • Week 6 (Feb 16*-22): How does gas flow into galaxies?
  • Week 7 (Feb 22-26): How do gaseous halos affect galaxy evolution?
  • Week 8 (Mar 1-5): What future observations will transform our understanding?

*Note that program events will not be held on two Monday US holidays, January 18 (Martin Luther King Day) and February 15 (Presidents’ Day)