India’s foray into the exploration of cosmic mysteries reached a significant milestone with the XSPECT payload on XPoSat, the country’s first X-ray polarimetric mission, capturing its inaugural light from the Cassiopeia A (Cas A) supernova remnant. Launched on January 1, 2024, XPoSat carries two cutting-edge instruments, the POLarimeter Instrument in X-rays (POLIX) and the X-ray SPECtroscopy and Timing (XSPECT), both aligned to unravel the enigmatic nature of cosmic X-ray sources.
The POLIX instrument focuses on investigating X-ray polarization in medium-energy X-rays, while the XSPECT payload engages in continuous and long-term spectral and temporal studies of X-ray sources in the soft X-ray band. The collective capabilities of these instruments position XPoSat as a crucial asset in advancing our understanding of celestial phenomena in the high-energy X-ray spectrum.
In a noteworthy development during its performance verification phase, the XSPECT payload was directed towards the Cassiopeia A supernova remnant, a celestial source widely used for instrument evaluation. The observation, which commenced on January 5, 2024, marked the first light capture by XSPECT, revealing the emission lines of elements such as Magnesium, Silicon, Sulphur, Argon, Calcium, and Iron within the Cassiopeia A supernova remnant.
Figure 1: [Insert Image] XSPECT sees supernova remnant Cassiopeia A (Cas A). The spectrum includes both Galactic Cosmic Ray (GCR) background and Cosmic X-ray Background (CXB). The flux above 8 keV is mainly due to both CXB and GCR. The spectrum shown in the figure is for a total integration time of 20 ksec collected over multiple orbits.
Developed by the Space Astronomy Group of U R Rao Satellite Centre (URSC)/ISRO in Bengaluru, the XSPECT payload’s continuous observations showcase its long-duration capabilities, promising valuable contributions to unraveling high-energy phenomena in the universe. The spectrum analysis not only enhances our understanding of the Cassiopeia A supernova remnant but also provides insights into the elemental composition of the remnants, contributing to broader scientific inquiries.
As XSPECT continues its mission to explore cosmic X-ray sources, its role in providing detailed spectral and temporal studies is expected to yield significant scientific breakthroughs. The success of capturing the first light from the Cassiopeia A supernova remnant underscores the potential of Indian space exploration in contributing to the global understanding of the cosmos and its intricate mysteries. XPoSat, with its advanced payloads, stands as a testament to India’s commitment to space exploration and scientific advancements on the international stage.