Context

• Astrosat, India's first multi-wavelength space-based observatory, has detected intense sub-second X-ray bursts emanating from a neutron star with an ultrahigh magnetic field.
• This discovery has the potential to shed light on the complex astrophysical conditions surrounding magnetars.Key

Points

• Magnetars are neutron stars distinguished by an ultrahigh magnetic field, more than a quadrillion times that of Earth.
• These celestial bodies emit high-energy electromagnetic radiation as a result of the decay of their magnetic fields.
• Additionally, magnetars exhibit remarkable temporal variability, including slow spin, rapid spin-down, and brief but intense bursts, extending to bursts lasting months.
• Such a magnetar, designated SGR J1830-0645, was identified by NASA's Swift spacecraft in October 2020.
• This relatively young and isolated neutron star, about 24,000 years old, inspired scientists from the Raman Research Institute (RRI) and the University of Delhi to conduct an in-depth study using AstroSat's instruments.
• One of its main objectives was to detect 67 short sub-second X-ray bursts with an average duration of 33 milliseconds.
• Of these explosions, the brightest lasted about 90 milliseconds.
• The research concluded that SGR J1830-0645 is a typical magnetar that displays an emission line in its spectra.
• However, the study acknowledges that the origin of this emission line – whether from iron fluorescence, characteristics of the proton cyclotron line, or instrumental effects – remains a matter of debate.
• The energy dependence in SGR J1830-0645 was different from that seen in many other magnetars.
• Here, there were two thermal blackbody emission components originating from the neutron star surface (radii of 0.65 and 2.45 km).
• Thus, this research contributes to our understanding of magnetars and their extreme astrophysical conditions.

IMPORTANT FACTS FOR EXAM 

Astrosat

• India's first dedicated multi-wavelength space observatory.
• This is the first dedicated Indian astronomy mission.
• Its objective is to simultaneously study celestial sources in the X-ray, optical and UV spectral bands.
• AstroSat, with a lift-off mass of 1515 kg, was launched by the Indian launch vehicle PSLV on September 28, 2015 from the Satish Dhawan Space Centre, Sriharikota into a 650 km orbit inclined at an angle of 6 degrees to the equator.
• The ISRO Telemetry, Tracking and Command Network (ISTRAC), the spacecraft control center at the Mission Operations Complex (MOX), Bengaluru, manages the satellite throughout its mission life.
• Scientific objective: To understand high energy processes in binary star systems containing neutron stars and black holes.