India’s X-Ray Polarimetry Astronomy Endeavour
India is set to launch its first X-Ray Polarimeter Satellite (XPoSat), aiming to investigate the polarization of intense X-Ray sources.
While space-based X-Ray astronomy has been established in India, focusing predominantly on imaging, time-domain studies, and spectroscopy, this upcoming mission marks a major value-addition.
The astronomy community is particularly enthused about the prospect of a systematic exploration into the polarization of X-Rays emitted by astronomical sources.
This research, supplementing traditional time and frequency domain studies, introduces a novel dimension to X-Ray astronomy, generating anticipation and excitement within the scientific community.
India’s X-Ray Polarimetry Astronomy Endeavour
The XPoSat Mission
The primary payload of XPoSat, POLIX (Polarimeter Instrument in X-rays), is designed to measure polarimetry parameters—specifically the degree and angle of polarization—in the medium X-ray energy range of 8-30 keV photons originating from astronomical sources.
Complementing this, the XSPECT (X-ray Spectroscopy and Timing) payload will provide spectroscopic information within the energy range of 0.8-15 keV.
The POLIX payload is developed by the Raman Research Institute (RRI), Bangalore, with support from the ISRO centres. The XSPECT payload is developed by the U R Rao Satellite Centre (URSC), ISRO.
The XPoSat Mission
XSPECT is an X-ray Spectroscopy and Timing instrument, designed to offer fast timing and excellent spectroscopic resolution in soft X-rays (0.8-15 keV).
XSPECT also monitors changes in line flux and profile, offering simultaneous, long-term temporal monitoring of soft X-ray emission.
The instrument employs an array of Swept Charge Devices (SCDs) with an effective area exceeding 30 cm² at 6 keV and an impressive energy resolution of less than 200 eV at 6 keV.
XSPECT employs passive collimators to reduce background by narrowing its field of view. This payload is anticipated to observe a variety of sources, including X-ray pulsars, black hole binaries, low-magnetic field neutron stars (NS), active galactic nuclei (AGNs), and magnetars.
International Trend in Space-Based X-Ray Polarimetry
Internationally, space-based study of X-Ray polarization is gaining utmost importance. The Imaging X-ray Polarimetry Explorer (IXPE) mission, launched on Dec 09, 2021, represents NASA’s inaugural space-based endeavor, focused on scrutinizing X-ray polarization across various celestial objects.
IXPE is dedicated to unraveling the mysteries surrounding some of the universe’s most extreme phenomena. These include the study of the remnants of supernova explosions, the particle streams emitted by feeding black holes, and other intriguing cosmic events.
