The first driver for the design of POLLUX is to take advantage of the large collecting power of LUVOIR -- providing a sensitivity threshold raised by a factor of 10 to 25 with respect to Hubble in the UV --, of its pointing stability and very dark background, to operate on a broad spectral range (90 to 400 nm), at very high spectral resolution (R = 120,000). These two specificities are mandatory to probe the thousands of atomic and molecular transitions of most of the chemical species in the Universe, uniquely available in the space UV band. This will allow to follow the life cycle of matter over cosmic time, from galaxies forming stars out of interstellar gas and grains, and stars forming planets, to the various forms of feedback into the interstellar and intergalactic medium (ISM and IGM), including black hole accretion disks in active galactic nuclei (AGN).
The second driver of POLLUX is its unique spectropolarimetric capabilities, that will open-up a new parameter space in Astrophysics, most notably since at high spectral resolution, we are often photon starved with current facilities. In exoplanet science, it will allow us to explore a wide range of planetary systems, pushing towards smaller, rocky planets and younger systems, to understand the early phases of planet formation and evolution, and probe the physical and chemical evolution of disks and young planetary systems. POLLUX in its spectropolarimetric mode will also deliver unprecedented constraints about the physical properties and altitude of dust and aerosols in the upper atmosphere of solar system planets, and exoplanets. Spectropolarimetry with POLLUX will enable the characterization of the magnetospheres of stars and planets, and their interactions, hence to explore the conditions for the emergence of life on exoplanets. On a broader context, circular and linear polarisation in the UV will allow to provide a full picture of magnetic field properties and influence for an unprecedented variety of media and objects, from AGN outflows to all kinds of stars, and stellar explosions – the supernovae - and remnants, the ISM and IGM. Since the parameter space opened by POLLUX is essentially uncharted territory, its potential for groundbreaking discoveries is tremendous. It will also neatly complement and enrich some of the cases advanced for LUMOS, the multi-object UV spectrograph for LUVOIR. In the links below we outline a selection of key science topics driving the POLLUX design.
Science cases :
- Stellar magnetic fields across the Hertzsprung-Russell diagram
- What are the characteristics of exoplanets atmospheres and how do planets interact with the host stars?
- The various phases of the ISM and extragalactic IGM
- Dust composition and magnetic field strength of unresolvable regions of AGNs
- Testing fundamental physics and cosmology using absorption lines towards quasars
- Solar system: surfaces, dust scattering and auroral emissions