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Published August 2021 | Accepted Version
Journal Article Open

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast


The measurement of the polarization of the Cosmic Microwave Background (CMB) radiation is one of the current frontiers in cosmology. In particular, the detection of the primordial divergence-free component of the polarization field, the B-mode, could reveal the presence of gravitational waves in the early Universe. The detection of such a component is at the moment the most promising technique to probe the inflationary theory describing the very early evolution of the Universe. We present the updated performance forecast of the Large Scale Polarization Explorer (LSPE), a program dedicated to the measurement of the CMB polarization. LSPE is composed of two instruments: LSPE-Strip, a radiometer-based telescope on the ground in Tenerife-Teide observatory, and LSPE-SWIPE (Short-Wavelength Instrument for the Polarization Explorer) a bolometer-based instrument designed to fly on a winter arctic stratospheric long-duration balloon. The program is among the few dedicated to observation of the Northern Hemisphere, while most of the international effort is focused into ground-based observation in the Southern Hemisphere. Measurements are currently scheduled in Winter 2022/23 for LSPE-SWIPE, with a flight duration up to 15 days, and in Summer 2022 with two years observations for LSPE-Strip. We describe the main features of the two instruments, identifying the most critical aspects of the design, in terms of impact on the performance forecast. We estimate the expected sensitivity of each instrument and propagate their combined observing power to the sensitivity to cosmological parameters, including the effect of scanning strategy, component separation, residual foregrounds and partial sky coverage. We also set requirements on the control of the most critical systematic effects and describe techniques to mitigate their impact. LSPE will reach a sensitivity in tensor-to-scalar ratio of σ_r < 0.01, set an upper limit r < 0.015 at 95% confidence level, and improve constraints on other cosmological parameters.

Additional Information

© 2021 IOP Publishing Ltd and Sissa Medialab. Received 28 August 2020; Accepted 5 July 2021; Published 2 August 2021. The development of LSPE is supported by ASI (grant LSPE I/022/11/0) and INFN. We acknowledge the usage of the HEALPix[150] and am software packages, computational resources from NERSC, Cineca and CNAF.We acknowledge support from the COSMOS network (www.cosmosnet.it) through the ASI (Italian Space Agency) Grants 2016-24-H.0 and 2016-24-H.1-2018, and Sapienza University. JARM, RGS and MPdT acknowledge financial support from the Spanish Ministry of Science and Innovation (MICINN) under the project AYA2017-84185-P, and the European Union's Horizon 2020 research and innovation programme under grant agreement number 687312 (RADIOFOREGROUNDS). The authors gratefully acknowledge the time and expertise devoted to reviewing the manuscript by the referees.

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Accepted Version - 2008.11049.pdf


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Additional details

August 22, 2023
August 22, 2023