In a pioneering move, which is aimed at advancing the understanding of the cosmos, the Indian Space Research Organisation (ISRO) has unveiled its latest project, the XPoSat (X-Ray Polarimeter Satellite).
Following the missions to the Moon (Chandrayaan Series) and Aditya L1 Solar Mission, ISRO is now directing kits attention towards unravelling the mysteries surrounding bright astronomical X-ray sources in extreme conditions.
Unravelling the cosmic mysteries of the Star
The XPoSat Mission represents the first dedicated polarimetry venture, with its primary goal being the investigation of various phenomena with luminous astronomical X-ray sources. Being positioned in a Low Earth Orbit (LOE), this spacecraft will carry two crucial scientific instruments engineered to gather invaluable data.
The leading instrument, known as the POLIX (Polarimeter Instruments in X-ray), has been meticulously designed to measure polarimetry parameters, including the degree and angle of polarisation. Its focus will be on the medium X-ray energy range, specifically targeting photons of astronomical origin within the 8-30 KV range.
In tandem with the POLIX, the XSPECT (X-ray Spectroscopy and Timing) instrument will play a vital role by providing spectroscopy data in the range of 0.8 to 15 keV.
What makes the XPoSat mission special?
ISRO underscores that the emission mechanisms observed in various celestial sources such as black holes, neutron stars, active galactic nuclei and pulsar wind nebulae arise from intricate physical processes that challenge our current understanding.
While the space-based observatories have yielded significant insights through spectroscopic and timing data, the precise nature of these emissions remains enigmatic, as acknowledged by ISRO officials.
The inclusion of polarimetry measurements introduces two additional dimensions to our understanding: the degree of polarisation and the angle of polarization. Consequently, it serves as a valuable diagnostic tool for comprehending the emission processes originating from the astronomical sources explained by ISRO.
The Integration of polarimetric observations with spectroscopic measurements is anticipated to break down any barrier that is present by several theoretical models pertaining to astronomic processes. The amalgamation of data is poised to become the principal avenue of research for the Indian Scientific community throughout the XPoSat mission.
POLIX functioning in the range of 8-30 keV is composed of a collimator, a scatterer and for X-ray proportional counter detectors. The collimator narrows the fields of view to three degrees by three degrees, ensuring that only one prominent source is observed at any given time during most observations.
POLIX mission will encompass the study of approximately 40 bright astronomical sources spanning various categories over the intended five-year duration of the XPoSat missions. This distinction marks it as the inaugural payload dedicated to polarimetry measurements with the medium X-ray energy band. The XSPECT, designated as the X-ray spectroscopy and timing payload, will offer swift timing measurements and remarkable spectroscopic resolution in the realm of soft X-rays.
In tandem with POLIX extended observations for the X-ray polarisation measurement, the XSPECT will facilitate continuous monitoring of the spectral state fluctuations, modifications in line flux and profile and concurrent long-term temporal tracking of the soft X-ray emissions within the energy range within the range of 0.8-15 keV.
XSPECT targeted sources encompass a spectrum of celestial objects, including X-ray pulsars, blackhole binaries, low magnetic field neutron stars within the low mass X-ray binaries and active galactic nuclei and Magnetars.