POLARIX: a pathfinder mission of X-ray polarimetry

TL;DR

POLARIX is a pioneering X-ray polarimetry mission utilizing Gas Pixel Detectors to measure polarization in celestial X-ray sources, enhancing understanding of astrophysical phenomena beyond traditional spectral and timing observations.

Contribution

It introduces a dedicated X-ray polarimetry mission with innovative Gas Pixel Detectors and a novel observational strategy to measure polarization in celestial X-ray sources.

Findings

Achieves 12% minimum detectable polarization for 1 mCrab sources.

Provides 20 arcsec angular resolution and 20% energy resolution at 6 keV.

Plans to operate for one year with community access to data.

Abstract

Since the birth of X-ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. Polarimetry, instead, remained basically unprobed. X-ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. POLARIX is a mission dedicated to X-ray polarimetry. It exploits the polarimetric response of a Gas Pixel Detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. Three Gas Pixel Detectors are coupled with three X-ray optics which are the heritage of JET-X mission. POLARIX will measure time resolved X-ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 arcmin $\times$ 15 arcmin and with an energy resolution of 20 % at 6 keV. The Minimum Detectable Polarization is 12 % for a source having a flux of 1 mCrab and 10^5 s of observing time. The satellite will be placed in an equatorial orbit of 505 km of altitude by a Vega launcher.The telemetry down-link station will be Malindi. The pointing of POLARIX satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. POLARIX data are for 75 % open to the community while 25 % + SVP (Science Verification Phase, 1 month of operation) is dedicated to a core program activity open to the contribution of associated scientists. The planned duration of the mission is one year plus three months of commissioning and SVP, suitable to perform most of the basic science within the reach of this instrument.