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Speaker: Boryana Hadzhiyska (UC Berkeley) – Title: Solving big-scale problems with small-scale models in the era of CMB-S4
April 2 @ 4:00 pm - 5:00 pm
Research Progress Meeting
Date: April 2, 2024
Time: 4:00- 5:00 pm
Location: Sessler Conference Room- 50A-5132 [In-Person and HYBRID]
Speaker: Boryana Hadzhiyska (UC Berkeley)
Title: Solving big-scale problems with small-scale models in the era of CMB-S4
Abstract: In this talk, I will focus on some of the new opportunities and new challenges that CMB-S4, the next-generation cosmic microwave background (CMB) experiment, presents, and I will offer a viable path forward to meeting and exceeding the goals we have set up for it. The CMB has played a huge role in shaping our understanding of the history, evolution and contents of our Universe. From our observations of the CMB, we have attained a good grasp of about 13.8 billion years of cosmic history, but our direct and indirect observations are limited to a much smaller range in energy scale, which leaves unresolved some of the biggest puzzles such as the mechanism that seeded the primordial fluctuations and the nature of the dark sector. I will discuss how we can leverage observations of the CMB to learn about these much earlier periods of cosmic history and also, how the CMB provides complementary probes of the lower-redshift universe. On large scales, the B-mode polarization signal can reveal the origin of primordial fluctuations, whereas the small-scale signal holds information about the presence of non-standard light relics and the sum of the neutrino masses. However, measuring the primordial signal is a non-trivial task, as on its way to us, the signal has picked up contributions from lensing and astrophysical sources, known as foregrounds. The best way to design accurate approaches for mitigating these foregrounds is via realistic all-sky simulations. I will present new techniques for painting foregrounds onto large-volume simulations, using physically motivated models that close the loop between simulations and observations. In addition, I will discuss ways of optimizing the CMB lensing reconstruction techniques, which is crucial for improving our constraints on primordial quantities such as the number of light relics and the tensor-to-scalar ratio as well as the sum of neutrino masses. Finally, I will argue that synergies between CMB secondaries and large-scale structure surveys can place tight constraints on cosmology and astrophysics. The measurement precision of CMB-S4 will be unmatched, but in order to make the most out of it, we need a big step-up in our analysis and theory tools, including the development of realistic all-sky simulations as well as techniques for optimal extraction of the small-scale cosmological signal.
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https://lbnl.zoom.us/j/95679892182?pwd=RU5xU2dDRFNabnR1U3pQMklkYWFIdz09
Meeting ID: 956 7989 2182
Passcode: 169037