PRIMA: science cases and requirements for the photometric and polarimetric PRIMAger far-infrared camera

PRIMA is a cryogenically-cooled, far-infrared observatory for the community for the beginning of the next decade (∼2031). It features two instruments, PRIMAger and FIRESS. The PRIMAger instrument will cover the mid-IR to far-IR wavelengths, from about 25 to 260 µm. Hyperspectral imaging can be obtained in 12 medium-resolution bands (R ∼ 10, more precisely a linear variable filter) covering the wavelength range from 25 to 80 micrometers, and broad-band (R ∼ 4) photometric and polarimetric imaging can be carried out in four bands between 80 and 260 µm. PRIMAger's unique and unprecedented scientific capabilities will enable study, both in PI and GO programs, of black hole and star-formation coevolution in galaxies, the evolution of small dust grains over a wide range of redshift, and the effects of interstellar magnetic fields in various environments, as well as opening up a vast discovery space with its versatile imaging and polarimetric capabilities. One of the most ambitious possibilities is to carry out an all-sky far-IR survey with PRIMAger, creating a rich data set for many investigations. The design of PRIMAger is presented is an accompanying paper (Ciesla et al., SPIE Astronomical Telescopes + Instrumentation 2024).