The Primordial Inflation Explorer (PIXIE): Mission Design and Science Goals

TL;DR

PIXIE is a proposed space mission designed to measure the cosmic microwave background's spectrum and polarization with unprecedented sensitivity, aiming to uncover fundamental insights into the universe's origin, composition, and evolution.

Contribution

It introduces a novel, highly sensitive Fourier transform spectrometer for CMB measurements, significantly surpassing previous missions like COBE/FIRAS, and outlines its science goals and mission design.

Findings

Enhanced sensitivity over 1000 times greater than COBE/FIRAS

Full-sky polarization maps near cosmic variance limit

Constraints on primordial processes and dark matter interactions

Abstract

The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission concept to measure the energy spectrum and linear polarization of the cosmic microwave background (CMB). A single cryogenic Fourier transform spectrometer compares the sky to an external blackbody calibration target, measuring the Stokes I, Q, U parameters to levels ~200 Jy/sr in each 2.65 degree diameter beam over the full sky, in each of 300 frequency channels from 28 GHz to 6 THz. With sensitivity over 1000 times greater than COBE/FIRAS, PIXIE opens a broad discovery space for the origin, contents, and evolution of the universe. Measurements of small distortions from a CMB blackbody spectrum provide a robust determination of the mean electron pressure and temperature in the universe while constraining processes including dissipation of primordial density perturbations, black holes, and the decay or annihilation of dark matter. Full-sky maps of linear polarization measure the optical depth to reionization at nearly the cosmic variance limit and constrain models of primordial inflation. Spectra with sub-percent absolute calibration spanning microwave to far-IR wavelengths provide a legacy data set for analyses including line intensity mapping of extragalactic emission and the cosmic infrared background amplitude and anisotropy. We describe the PIXIE instrument sensitivity, foreground subtraction, and anticipated science return from both the baseline 2-year mission and a potential extended mission.