March 26, 2019

Speaker: Brant Robertson

Contact Information: brant@ias.edu

Title: Constraining Cosmic Reionization with Hubble, James Webb, and WFIRST

Abstract: Understanding cosmic reionization requires the identification and characterization of early sources of hydrogen-ionizing photons. Through a series of intense observational campaigns with Wide Field Camera 3 (WFC3) aboard Hubble Space Telescope (HST) we have now systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. High-redshift observations with HST WFC3/IR including UDF12, CANDELS, and the Frontier Fields provide the best constraints to date on the abundance, luminosity distribution, and spectral properties of early star-forming galaxies. HST WFC3/UVIS programs including LACES probe the hydrogen-ionizing photon escape fraction directly by imaging distant galaxies in the Lyman continuum. We synthesize results from these HST campaigns and the most recent constraints from Planck CMB observations to infer redshift-dependent ultraviolet luminosity densities, reionization histories, and the electron scattering optical depth evolution consistent with the available data. We will then preview how James Webb Space Telescope and eventually WFIRST will provide a new window into the reionization epoch and teach us about the physics of galaxy formation in the early universe.

Visit Schedule:

Tuesday (26 Mar 2019):


  • 10:30 a.m.: Coffee / Talk Prep

  • 11:00 a.m.: Colloquium

  • 12:15 p.m.: Bahcall Lunch

  • 2:00 p.m.:

  • 2:30 p.m.: Alwin Mao (019)

  • 3:00 p.m.:

  • 3:30 p.m.: Tea with grad students

  • 4:00 p.m.: Patrick Crumley (124)

  • 4:30 p.m.: Jenny Greene (001)

  • 5:00 p.m.: Eve Ostriker (136)

  • 5:30 p.m.: Jo Dunkley (118)

  • 6:00 p.m.: DINNER WITH HOST - meet in Grand Central, Jenny

Dinner Sign-up (students have priority; 8 MAX) - add your name here:

1. Speaker: Brant Robertson

2. Faculty host: Jo Dunkley

3. Postdoc host: Patrick Crumley

4. Christina Kreisch

5. Ivanna Escala

6. Jenny Greene

7. Zack Li

8. Kris Pardo

NO MORE THAN 8 PEOPLE (otherwise it is very difficult to properly interact with the speaker)