Formation, Possible Detection and Consequences of Highly Magnetized Compact Stars

TL;DR

This paper reviews the development and implications of highly magnetized compact stars, including neutron stars and white dwarfs, highlighting their formation, detection, and role in phenomena like supernovae and gravitational waves.

Contribution

It provides a comprehensive overview of recent advances in understanding highly magnetized compact stars and explores their potential as progenitors of peculiar supernovae and other astrophysical phenomena.

Findings

Magnetized white dwarfs can have super-Chandrasekhar masses.

Magnetic fields significantly alter mass-radius relations.

These stars may explain certain peculiar supernovae and gravitational wave signals.

Abstract

Over the past several years, there has been enormous interest in massive neutron stars and white dwarfs due to either their direct or indirect evidence. The recent detection of gravitational wave event GW190814 has confirmed the existence of compact stars with masses as high as $\sim2.5-2.67M_{\odot}$ within the so-called mass gap, indicating the existence of highly massive neutron stars. One of the primary goals to invoke massive compact objects was to explain the recent detections of over a dozen Type Ia supernovae, whose peculiarity lies with their unusual light curve, in particular the high luminosity and low ejecta velocity. In a series of recent papers, our group has proposed that highly magnetised white dwarfs with super-Chandrasekhar masses can be promising candidates for the progenitors of these peculiar supernovae. The mass-radius relations of these magnetised stars are significantly different from those of their non-magnetised counterparts, which leads to a revised super-Chandrasekhar mass-limit. These compact stars have wider ranging implications, including those for soft gamma-ray repeaters, anomalous X-ray pulsars, white dwarf pulsars and gravitational radiation. Here we review the development of the subject over the last decade or so, describing the overall state of the art of the subject as it stands now. We mainly touch upon the possible formation channels of these intriguing stars as well as the effectiveness of direct detection methods. These magnetised stars can have many interesting consequences, including reconsideration of them as possible standard candles.