In a groundbreaking leap for Indian space exploration, the country is set to launch its first X-Ray Polarimeter Satellite (XPoSat), a mission designed to investigate the polarization of intense X-Ray sources in the cosmos. While India has a well-established presence in space-based X-Ray astronomy, with a focus on imaging, time-domain studies, and spectroscopy, the XPoSat mission introduces a new dimension by systematically exploring the polarization of X-Rays emitted by astronomical sources.
XPOSAT
A New Frontier in X-Ray Astronomy
Scheduled for observation from a Low Earth Orbit (LEO) at approximately 650 kilometers altitude and a low inclination of about 6 degrees, the XPoSat spacecraft carries two scientific payloads. These payloads enable simultaneous studies of temporal, spectral, and polarization features of bright X-Ray sources. The mission's primary objectives include measuring X-Ray polarization in the energy band of 8-30 keV and conducting long-term spectral and temporal studies of cosmic X-Ray sources in the energy band of 0.8-15 keV. With a planned mission life of approximately 5 years, XPoSat's payloads will observe X-Ray sources during the satellite's transit through Earth's shadow, known as the eclipse period.
XPOSAT
Evolution of Astronomical Instrumentation
To appreciate the significance of the XPoSat mission, it's essential to reflect on the evolution of astronomical instrumentation. The journey began over four centuries ago with the invention of the optical telescope, progressing from observing celestial bodies with visible light to capturing images, monitoring starlight fluctuations, and eventually embracing spectroscopy. This integration of imaging and spectroscopy paved the way for instruments capable of capturing celestial bodies at diverse wavelengths, including captivating images of the Sun in visible, ultraviolet, and X-Ray wavelengths.
The Importance of X-Ray Polarization
In the realm of observational astronomy, polarization emerged as a crucial tool. While time and frequency domain studies provided valuable insights, polarization, considered one of the intrinsic properties of light, offered a deeper understanding of the processes generating radiation. In particular, X-Ray polarization serves as a diagnostic tool for examining the radiation mechanism and geometry of celestial sources.
The XPoSat Mission: Unraveling Cosmic Secrets
The XPoSat mission comprises two key payloads: POLIX (Polarimeter Instrument in X-rays) and XSPECT (X-ray Spectroscopy and Timing). POLIX, developed by the Raman Research Institute, focuses on measuring the degree and angle of polarization in the medium X-ray energy range of 8-30 keV. XSPECT, developed by the U R Rao Satellite Centre, offers spectroscopic information in the energy range of 0.8-15 keV, providing fast timing and excellent spectroscopic resolution in soft X-rays.
XPoSat User Meet: Fostering Collaboration
Recognizing the potential impact of XPoSat on advancing scientific understanding in Astronomy, ISRO organized a one-day XPoSat User Meet on May 25, 2023. The event brought together approximately 150 participants from 20 institutes and universities nationwide. Discussions centered on the significance of X-ray polarization measurements, anticipated impacts on various astronomical sources, and modeling requirements for interpreting XPoSat data. The meeting emphasized the importance of engaging the student community and building expertise in X-Ray polarimetry in India.
International Collaboration: A Global Trend
Internationally, the study of X-Ray polarization is gaining prominence, exemplified by NASA's Imaging X-ray Polarimetry Explorer (IXPE) mission. Launched in December 2021, IXPE focuses on scrutinizing X-ray polarization across various celestial objects. The XPoSat mission, with its complementary energy range to IXPE, promises coordinated observations that will provide a wide window for polarimetric studies of bright X-ray sources.
Physics of Polarization: Unveiling Cosmic Secrets
Understanding the basic physics of polarization reveals its role as a diagnostic tool in astronomy. Light, described as an electromagnetic wave, exhibits polarization, with the degree and angle providing crucial information about the processes generating radiation. In astronomy, X-Ray polarization becomes a key parameter, offering insights into phenomena such as accreting black holes, pulsars, and magnetic fields.
Payloads
XSPECT POLIX
Epilogue: Advancing Scientific Frontiers
In conclusion, India's XPoSat mission marks a significant advancement in the exploration of cosmic mysteries. The combination of polarimetric observations and spectroscopic measurements is poised to enhance our comprehension of the intricate emission processes from diverse celestial sources. XPoSat's anticipated contributions to understanding black holes, neutron stars, and active galactic nuclei showcase its potential to reshape our understanding of the universe. As ISRO encourages collaboration and engages the scientific community, XPoSat emerges as a beacon for future advancements in space-based X-Ray polarimetry, fostering a network of expertise within the Indian Astronomy community and beyond. The mission, with its planned 5-year lifespan, holds the promise of unraveling cosmic secrets and contributing to the global pursuit of knowledge in the vast expanse of space.
Madhava Space Research Organisation
Bulandshahar, Uttar Pradesh
India (Bharat)
Telephone: +91 63 9791 9165
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