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In search of primordial gravitational waves

A new space project for SISSA

Following years of study in the largest research centres in Japan, Europe and North America, on 21 May 2019 the Japanese Space Agency (JAXA/ISAS) announced the selection of the LiteBIRD satellite (litebird.jp) as strategic satellite mission for fundamental sciences, to be accomplished within the next decade. The satellite will be launched in 2028, and the main purpose will be the search for gravitational waves produced in the primordial Universe. These waves are produced in the process known as Cosmic Inflation, which occurred an infinitesimal fraction of a second after the Big Bang, a time in which the Universe experienced an almost exponential expansion.

Spacetime vibrates following this titanic expansion, generating gravitational waves that reach cosmological scales leaving their imprint in the only one observable in which we can search for them, namely B-mode polarisation of cosmic microwave background.

This a global undertaking. The collaboration involves 150 scientists in Japan, Europe, United States and Canada, who will support this effort at all levels, from the realisation of structural components to the analysis of data to obtain the most scientific results.

Through the direct support of the Italian Space Agency (ASI), Italy has played a fundamental role in the acceleration imparted to the preparatory studies in the last year, realised within the coordination for the studies on cosmic microwave background, COSMOS (cosmosnet.it), which includes scientists in ASI, in the Universities and in the National Institutes of Nuclear Physics and Astrophysics. In particular the young researchers of SISSA, Nicoletta Krachmalnicoff and Davide Poletti, have completed the delicate task of simulating background radiation contamination produced by the other known astrophysical processes, namely their overlap with it in the frequencies observed by the satellite, and of showing our ability to remove them to be able to “see” the primordial gravitational waves. This task has been carried out by febrile daily consultations with colleagues all over the world, progress in studies and in the most advanced algorithms on the matter, until the expected announcement of the selection of recent days.

“A new phase is beginning” says Carlo Baccigalupi, deputy-coordinator for the Astrophysics and Cosmology group at SISSA and responsible for the studies on cosmic microwave background “The path for the observation of this sign of fundamental physics in the primordial Universe is now marked out and composed of observers situated on the Earth, in the Atacama Desert in Tenerife and in the South Pole, to observe limited regions of sky at high resolution. This path is now accompanied by the satellite undertaking, unique in its ability to find the imprint of gravitational waves with a longer wavelength, after the Planck satellite and with an accuracy that is 100 times greater”. The official Symposium to start the works will take place in Tokyo in the first week of July. “For SISSA, involved in the front line in these studies, it is a new challenge towards frontier research for knowledge in fundamental Physics”.

More info on the satellite