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Abstract:

In recent years, Line-intensity mapping (LIM) has emerged as a new way to efficiently survey our Universe. LIM simply creates broad, coarse maps of the aggregate emission (or absorption) of particular spectral lines. By forgoing the identification of individual objects such as galaxies, LIM captures emission from objects that would be too faint to be individually detected. In this talk, I will discuss three recent efforts in LIM. First, I will summarize recent upper limits on the intensity mapping of the 21cm signal at high redshifts from the Hydrogen Epoch of Reionization Array (HERA). These limits are now strong enough that they rule out certain theory models of Cosmic Dawn (the era of first-generation stars and galaxies). Looking beyond our current limits, I will propose an idea for combining machine learning with 21cm observations to look beyond the messy astrophysics of Cosmic Dawn to constrain fundamental cosmological parameters. Finally, I will discuss a futuristic idea for combining LIM observations of multiple lines to selectively “cancel out” gravitational lensing effects from particular redshifts in Cosmic Microwave Background (CMB) data. Taken together, these projects showcase the potential for LIM to strongly impact both astrophysics and cosmology as new experiments begin observing in the next few years.

Adrian Liu is an associate Professor of Physics at McGill University.

The McDonald Institute seminar will be held in Stirling 501. A Zoom link is also available and shared via email by the organizers. Please reach out to admin@mcdonaldinstitute.ca for access.