Polarimetric prospects of a new hard X-soft gamma-ray space mission for next decades

The measurement of the polarization of the high-energy photons from cosmic sources hasnow become a key observational parameter for understanding the emission mechanismsand the geometry of the active regions involved. Therefore, a mandatory requirement fornew instrumentation in this energy regime will provide high sensitivity for polarimetricmeasurements associated with spectroscopy and imaging.In this perspective, the Advanced Surveyor of Transient Events and Nuclear As-trophysics (ASTENA) mission, which includes two main instruments: the Wide fieldmonitor (WFM-IS), with a large effective area and a wide energy passband (2 keV – 20MeV); and the Narrow Field Telescope (NFT), with a broad energy passband (50–600keV) with focusing capabilities based on the use of an advanced Laue lens; will both pro-vide high sensitivity for polarimetric measurements. Furthermore, both instruments willinclude spectometers with a good 3D spatial resolution allowing to perform 3D Comptonpolarimetry, increasing the possibilities to optimize the event selection. Herein, we reporton the results of a Monte Carlo study devoted to optimize the configuration of both in-struments, in particular, the modulation factor (Q), the events detection efficiency (Eff)and the Minimum Detectable Polarization (MDP).