Milli-second burst detected by AstroSat in new high magnetic field neutron star

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Last Updated28/12/2023

AstroSat recently detected bright sub-second X-ray bursts from a newly discovered neutron star known as SGR J1830-0645.
This neutron star belongs to the rare category of magnetars, characterised by an ultrahigh magnetic field.

It is India’s first dedicated multi-wavelength space observatory.
Objective: To study celestial sources in X-ray, optical, and UV spectral bands simultaneously.
Launched by ISRO in September 2015, AstroSat has played a crucial role in astronomical research.
It was launched into a 650 km orbit inclined at an angle of 6 degrees to the equator.
The minimum useful life of the AstroSat mission is around 5 years.
It carries a total of five scientific payloads.
- It enables imaging and studying the temporal and spectral properties of galactic and extragalactic cosmic sources in a wide range of wavelengths on a common platform.

The Cadmium Zinc Telluride Imager (CZTI) on AstroSat has been pivotal in capturing GRBs.
CZTI specializes in high-energy, wide-field imaging, covering an energy range from 20 keV to over 200 keV.
Its capability to detect Compton scattered events allows the study of X-ray polarization, enhancing the understanding of GRBs.

The research identified SGR J1830-0645 as a unique magnetar displaying an emission line in its spectra.
The presence of emission lines in the spectra raises questions about their origin.
It suggests possibilities such as fluorescence of iron, proton cyclotron line feature or instrumental effects.
The energy-dependence observed in SGR J1830-0645 differs from other magnetars, with two thermal blackbody emission components originating from the neutron star's surface.

Magnetars are neutron stars with magnetic fields over one quadrillion times stronger than Earth's.
Magnetars also release vast amounts of energy in the form of flares, X-rays and gamma-ray bursts.
They are therefore associated with extreme events in the universe, making them perhaps the most bizarre objects in the cosmos next to black holes.
SGR J1830-0645, discovered in October 2020, is a relatively young and isolated magnetar with intriguing astrophysical conditions.