School of Physics Fall Colloquium Series- Dr. James Aguirre

James Aguirre(UPenn) Bridging Astrophysics and Cosmology with Line Intensity Mapping

Speaker: Dr. James Aguirre

Host: Jennifer Curtis

Title: Bridging Astrophysics and Cosmology with Line Intensity Mapping

Abstract: Line intensity mapping is a new, rapidly evolving observational and analysis technique for obtaining statistical information about the large-scale spatial and redshift distribution of astrophysical processes associated with the emission or absorption of a particular line, but which does not require producing high-resolution images.  It promises to be particularly powerful when used with lines that trace star formation and the evolution of galaxies, but for which instrumentation with the requisite sensitivity or angular resolution to detect individual galaxies is lacking, or the emission is intrinsically extended.  

I focus on two examples, the Hydrogen Epoch of Reionization Array (HERA) and the Terahertz Intensity Mapper (TIM), which use the lines of neutral hydrogen (21 cm at 27 > z > 6) and ionized carbon (158 micron at 1.5 > z > 0.5), respectively.  HERA, a low frequency radio interferometer operating in South Africa, investigates the conditions in the intergalactic medium during cosmic dawn (the birth of the first stars and stellar-mass black holes) by tracing the heating and ionization of hydrogen.  TIM is a balloon-borne far-infrared spectrometer to probe galaxies during "cosmic noon" (the peak of cosmic star formation).  In particular, I discuss how HERA's current and upcoming measurements can be used to constrain the optical depth to reionization, a major "nuisance parameter" for next-generation CMB measurements looking to constrain the sum of the neutrino masses, and how TIM’s may be used to add new insight to the cosmic star formation history.
I include recent results and progress from HERA, and new forecasts and constraints from archival data relevant to TIM, which is set to fly from Antarctica in late 2026.
 

Bio: James Aguirre was an undergraduate at Georgia Tech (BS Physics and Applied Math, 1997) and received his PhD in Physics from the University of Chicago under Stephan Meyer on the TopHat CMB balloon experiment.  He was a postdoc and an NRAO Jansky Fellow at the University of Colorado, Boulder, and then came to the University of Pennsylvania as an Assistant Professor in 2008.  He is broadly interested in the formation and evolution of galaxies and the interplay between galaxies and large-scale structure as traced through line intensity mapping (21 cm and far-infrared) and the cosmic microwave background. He has worked on a number of projects in radio and submillimeter wavelength instrumentation and analysis, including Bolocam, Z-Spec, PAPER, HERA, TIM, and the Simons Observatory.  

 

Event Details

Date/Time:

  • Date: 
    Monday, November 24, 2025 - 3:30pm to 4:30pm

Location:
 Marcus Nanotechnology 1116-1118