The Polocalc (POLarisation Orientation CALibrator for Cosmology) project, led by Federico Nati, Professor of Experimental Cosmology at the Department of Physics of the University of Milano-Bicocca, has just been awarded a €2.4 million ERC Advanced Grant by the European Union. Over the next five years, drones and balloons will be flown over the Atacama Desert in Chile at an altitude of almost 6,000 metres to create a constellation of calibration light sources that will provide an absolute reference system for the Simons Observatory telescopes. This innovative method will make it possible to discover never-before-observed phenomena such as gravitational waves in the early universe, unravelling some of the mysteries surrounding the birth of the cosmos and the nature of dark matter and dark energy.
ERC Advanced Grants are awarded by the European Research Council to established researchers who are recognised leaders in their field and have an excellent, particularly visionary and innovative research project. This is the first ERC Advanced Grant to be hosted directly at Milano-Bicocca.
"Astrophysical signals are usually calibrated using known celestial sources," explains Federico Nati, "but these do not always exist or have been observed with sufficient accuracy to be used to calibrate a reference scale. Unfortunately, this is precisely the case for cosmological signals that could be detected by measuring the polarisation of light from the primordial universe, the cosmic background radiation. This fossil radiation could contain polarised light signals predicted by the Big Bang theory.
These are very weak signals," continues the Milano-Bicocca professor, "which have never been observed before and which would prove the existence of primordial gravitational waves. Telescopes have gradually become more sensitive in order to detect them, but they lack an absolute reference for calibration, as there is currently no suitable celestial source. The project therefore proposes the creation of artificial ones, carried by drones and balloons, which will place polarised light emitters in the sky above the telescopes in the Atacama Desert in Chile, to be constructed and finely characterised in the Experimental Cosmology Laboratories of the University of Bicocca. The Simons Observatory telescopes, which will become operational this year at an altitude of 5200 metres, represent the largest programme for measuring the cosmic background radiation for years to come. This project will make it possible to achieve scientific goals that would otherwise be impossible, such as the discovery of cosmic birefringence, an effect that was previously only a theoretical hypothesis and that could make us sensitive to the presence of dark matter and dark energy.
At Polocalc, 6-7 researchers, research fellows and PhD students from Milano-Bicocca will work under the direction of Federico Nati.
Over the last ten years, the University of Milan has received funding for 16 ERC projects: 5 Starting Grants, 7 Consolidator Grants, 1 Proof of Concept, 2 Synergy Grants) and now Nati's Advanced Grant. "For our University, this funding is the culmination of a commitment that has led us for years to encourage our researchers to 'think big'," says Guido Cavaletti, Vice-Rector for Research at the University of Milan-Bicocca, "to push themselves to ever more ambitious limits, with an increasingly qualified and demanding international horizon. It is a success that clearly shows us that we are on the right track and we are therefore very confident, not only in the positive outcome of this specific research, but also in the possibility for other colleagues to obtain similar results in the European calls, where we have shown that we can be very competitive".
Photos of the project at this link
Federico Nati
Federico Nati (Rome, 1975) is an experimental astrophysicist and professor at the Department of Physics of the University of Milan-Bicocca, where he teaches experimental cosmology. For twenty-five years he has been building and using the most advanced telescopes to collect vast amounts of data on the origins of the cosmos and its evolution. Trained at La Sapienza University in Rome, he then worked in Chile for Princeton University, where he managed the field operations of the Atacama Cosmology Telescope at an altitude of 5200 metres, and at the University of Pennsylvania in Philadelphia in the United States, where he built the BLAST balloon telescope, which he launched in a suborbital flight at an altitude of 35 km with an international team from McMurdo Base in Antarctica. Since 2018, he has been conducting research at the University of Milano-Bicocca through several international collaborations, in particular for the construction of the Simons Observatory in Chile, the largest observatory for the CMB (cosmic background radiation), which will provide the most detailed