About Me

I am a postdoctoral fellow studying cosmology at the Canadian Institute for Theoretical Astrophysics in Toronto, ON. I completed my Ph.D. at the Johns Hopkins University Department of Physics and Astronomy under the supervision of Marc Kamionkowski. Currently, my primary research interests lie in the field of line intensity mapping, a novel method for exploring subjects ranging from large-scale structure to galaxy evolution in the high-redshift universe. Most of my work involves modeling efforts to forecast signals for upcoming intensity mapping experiments and the development of analysis techniques to extract useful physics from them.


60 St. George Street, Rm 1302
Toronto, ON Canada M5S 3H8


pcbreysse [at] cita.utoronto.ca



Johns Hopkins University

Ph.D. in Physics and Astronomy May 2017

Penn State University

B.S. in Physics, B.S. in Astronomy & Astrophysics May 2012

Research History

Canadian Institute for Theoretical Astrophysics, University of Toronto

Postdoctoral Fellow September 2017 - Present

Kamionkowski Group, Johns Hopkins University Department of Physics and Astronomy

Graduate Research Assistant June 2012 - August 2017



Full lists of my publications can be found on NASA ADS, inSPIRE, and arXiv



The Carbon Monoxide Mapping Array Pathfinder seeks to map star-forming gas during the era of galaxy assembly around redshift 3 through intensity mapping of CO lines. Science observations began in 2019 at the Owens Valley Radio Observatory. Future upgrades will allow mapping of CO lines during the Epoch of Reionization. I have been leading the COMAP science and modeling working group since 2018.


CCAT-prime, currently under construction in the Atacama, will among other interesting science make maps of CII emission during the Epoch of Reionization. I am a member of the CCATp Science Working Group.


EXCLAIM is a balloon-based intensity mapping experiment seeking to measure CII at redshift 3 and various CO transitions at lower redshifts in cross-correlation with BOSS galaxy maps. EXCLAIM is currently under construction at the NASA Goddard Space Flight Center. I am a member of the EXCLAIM science and analysis team.


Some of the earliest detections of intensity mapping signals were made by the Green Bank and Parkes telescopes in cross-correlation with galaxy surveys. I am working on applying a novel analysis to these data. The method, described here, makes it possible to extract non-Gaussian information from these maps which is inaccessible to conventional cross-correlation techniques.


I was a member of the Johns Hopkins Physics and Astronomy Graduate Students Outreach group, which gives talks and demonstrations in classrooms and events throughout Baltimore. I helped create a portable planetarium (shown at left), and used the free WorldWide Telescope software to design and run planetarium shows both at Johns Hopkins and all around the city.

I am active in many outreach activities at the University of Toronto. I have given public talks at Astronomy on Tap and AstroTours events. See here for a video of one of my talks. I also participate in the annual Planet Gazing Party event where thousands of people come to see the sky through a telescope, many for the first time in their lives