Detecting the Cosmic 21 cm Signal with Low-Frequency Radio Astronomy

Abstract: 21 cm cosmology – the concept of using radio telescopes to observe the highly redshifted 21 cm line of neutral hydrogen on cosmological scales – is a field with tremendous scientific potential. After nearly 20 years of experimental effort, however, a detection of the Epoch of Reionization (EoR) signal remains elusive. The fundamental challenge is a sea of other astrophysical "foreground" emission nearly five orders of magnitude stronger than the signal of interest, although the past two decades have revealed just how much the design of the instrument plays a role in compounding this problem. This talk will review the status of the field, including the lessons learned from a now-concluded first generation of experiments and updates from a second generation of experiments nearing completion. I will particularly emphasize the work being done with the Murchison Widefield Array (MWA) and our efforts to address the worsening challenge of human generated radio-frequency interference (RFI). Even if successful, however, these second-generation experiments will only be the beginning for 21 cm cosmology, and I will conclude by discussing future directions for the field, both on the ground and the lunar far side.

Bio: Professor Jonathan Pober works in the field of “21 cm cosmology” – a program of research to observe neutral hydrogen from the early universe through its hyperfine 21 cm emission line. His interests include both the development of new radio astronomy techniques to make these observations possible, and the physics of early universe galaxy formation and cosmology that they probe. He is a member of several ground-based radio telescope collaborations, including the Murchison Widefield Array in Western Australia. He arrived at Brown in January 2016; prior to that he was a postdoctoral fellow at the University of Washington. He received an MPhil from Cambridge in 2008 and a PhD from UC Berkeley in 2013. Prof. Pober was also recently awarded a NASA Roman Technology Fellowship to study the feasibility of putting a radio telescope on the far side of the moon.