The Large-Scale Polarization Explorer (LSPE)

Abstract

The LSPE is a balloon-borne mission aimed at measuring the polarization of the Cosmic Microwave Background (CMB) at large angular scales, and in particular to constrain the curl component of CMB polarization (B-modes) produced by tensor perturbations generated during cosmic inflation, in the very early universe. Its primary target is to improve the limit on the ratio of tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7% confidence. A second target is to produce wide maps of foreground polarization generated in our Galaxy by synchrotron emission and interstellar dust emission. These will be important to map Galactic magnetic fields and to study the properties of ionized gas and of diffuse interstellar dust in our Galaxy. The mission is optimized for large angular scales, with coarse angular resolution (around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload will fly in a circumpolar long duration balloon mission during the polar night. Using the Earth as a giant solar shield, the instrument will spin in azimuth, observing a large fraction of the northern sky. The payload will host two instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters, using large throughput multi-mode bolometers and rotating Half Wave Plates (HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz. The wide frequency coverage will allow optimal control of the polarized foregrounds, with comparable angular resolution at all frequencies.

Atacama Cosmology Telescope: Constraints on cosmic birefringence

“…In this paper, the constraints on cosmic birefringence anisotropies are derived using data from one region of the sky, which we label D56. D56 spans 456 deg 2 of the sky with the aspect ratio of 1:4 observed in both the 2014 and 2015 seasons at 150 GHz, and in the 2015 season at 90 GHz [2,46,47]; the map has an effective noise level of 14 µKarcmin for polarization. In addition to D56, we also use another region of the sky for a (swap-patch) null test, the region is called BOSS-N; this field was observed during the 2015 season and covers 1633 deg 2 of the sky with an effective noise level of roughly 30 µK-arcmin in polarization.…”

Needlet thresholding methods in component separation

“…In this section, we present the results obtained by applying the techniques described in the previous sections to different simulated data-sets. We generate two mock datasets using the PySM software [45], which mimic respectively observations of the Planck mission and of the SWIPE instrument of the forthcoming LSPE mission [49][50][51]. LSPE (Large Scale Polarization Explorer) is a forthcoming ASI mission aimed at the measurement of large scale CMB polarization fluctuations.…”

The STRIP instrument of the Large Scale Polarization Explorer: microwave eyes to map the Galactic polarized foregrounds

“…These will be important to map Galactic magnetic fields and to study the properties of ionized gas and of diffuse interstellar dust in our Galaxy. 6 LSPE will observe a 25% fraction of the sky in the Northern hemisphere by means of two instruments, complementary for frequency coverage and technology, SWIPE and STRIP. SWIPE 7 consists of three arrays of 110 large throughput multi-mode bolometers centered at the frequencies 140, 220 and 240 GHz.…”