Observing the Early Universe with LiteBIRD (Andrea Tartari, INFN Pisa)

Abstract: After the discovery of temperature anisotropies in the Cosmic Microwave Background maps (COBE-DMR, early ’90), Cosmology entered a new era, in which key “predictions” of Inflation could be tested. From then on, an impressive series of experiments, including two dedicated satellite missions (WMAP and Planck) contributed to root CMB Cosmology on a solid experimental ground. In the two decades following the COBE-DMR announcement, and after a 6 order-of-magnitude sensitivity improvement in angular power spectra, linearly polarised anisotropies have been discovered (E-modes, 2003; lensing B-modes, 2014) , thus paving the way towards the search for primordial B-modes, one of the most ambitious targets of Observational Cosmology. Primordial B-modes are linearly polarised large scale CMB anisotropies induced by a background of gravitational waves generated during Inflation, at energy scales ~10^15-10^16 GeV. Primordial B-mode detection, if any, would represent a milestone in our understanding of the Early Universe physics.
Now, thanks to the impressive success of superconducting sensor array deployment in large 100 mK focal planes (adequately multiplexed by SQUID-based low noise electronics), deeper and deeper maps of the CMB polarisation will be delivered in the next decade by ground-based and balloon-borne experiments and, in a complementary way, by the only space-based experiment scheduled today, that is, the JAXA-led LiteBIRD mission.

The complementarity stems from the fact that from ground one can exploit large aperture telescopes, large aberration-free focal planes and a variety of optical configurations suitable to target a number of cosmological observations (from the Sunyaev-Zel’dovich effect in cluster of galaxies, to lensing B-modes, thus constraining parameters such as the sum of neutrino masses), but with limitations on the accessibility of large angular scales and maximum observational frequencies (typically < 270 GHz) set by Earth’s atmosphere noise and instabilities. Conversely, space operation puts severe constraints on the instrument design, but it offers the chance of an extremely stable environment, where the predominant noise source can be the CMB itself. Since high frequencies (> 300 GHz) and full sky coverage are key ingredients for primordial B-modes search, a space mission will have unique capabilities in this field. LiteBIRD, a mission  explicitly tailored for primordial B-mode discovery, will observe the full sky for 3 years, from 34 to 448 GHz in 15 bands, and it will be operated in the Lagrangian point L2 in the late ’20. In this talk, I will review LiteBIRD science case and I will discuss all the most important features of the mission, including the focal plane cryogenic detector arrays.


Abstract e slide disponibili su: https://agenda.infn.it/event/29018/

Il seminario si terrà in presenza nella Sala Galilei (stanza 131) per un numero limitato di persone (32) e via Zoom al seguente indirizzo:


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