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Speaker: Zeeshan Ahmed, SLAC National Accelerator Laboratory
Abstract: The red-hot glow of the primordial universe, after 13.8 billion years of redshift, is observed today by our telescopes as the Cosmic Microwave Background (CMB). Spatial variations of CMB intensity and polarization across the sky provide a record of conditions in the early universe, possibly encoding signatures from cosmic inflation and traces of undiscovered relic particles. Additionally, the CMB ‘backlights’ the universe’s large-scale structure and picks up the influence of all matter, including neutrinos, on its way to us. Ground-based CMB imaging instrumentation has made generational leaps in sensitivity over the past few decades, while our understanding and mitigation of systematic errors in CMB measurements has advanced. Ongoing and upcoming experiments such as BICEP, South Pole Telescope and Simons Observatory will conduct the most sensitive search yet for inflation, complement DESI and Rubin Observatory in aiding our understanding of cosmic acceleration, and enhance studies of neutrinos and dark matter from direct experimental efforts. Additionally, a future observatory called CMB-S4 is the largest conceived ground-based CMB facility that plans to map over 40% of the Southern sky to unprecedented sensitivity in the 2030s. I will report on the design, status and latest results from these efforts.