Investigations of supernovae and supernova remnants in the era of SKA

Abstract

Supernovae are extremely luminous and can outshine an entire galaxy for a period of days. Two main physical mechanisms are used to explain supernova explosions: thermonuclear explosion of a white dwarf (Type Ia) and core collapse of a massive star (Type II and Type Ib/Ic). Type Ia supernovae serve as distance indicators that led to the di scovery of the accelerating expansion of the Universe. The exact nature of their progenitor systems however remain unclear. Radio emission from the interaction between the explosion shock front and its surrounding circumstellar medium (CSM) or interstellar medium (ISM) provides an important probe into the progenitor star’s last evolutionary stage. No radio emission has yet be en detected from Type Ia supernovae by current telescopes. The SKA will hopefully detect radio emission from Type Ia supernovae due to its much better sensitivity and resolution. There is a ’supernovae rate problem’ for the core collapse su pernovae because the optically dim ones are missed due to being intrinsically faint and/or due t o dust obscuration. A number of dust-enshrouded optically hidden supernovae should be discovered via SKA1-MID/survey, especially for those located in the innermost regions of their ho st galaxies. Meanwhile, the detection of intrinsically dim SNe will also benefit from SKA1. The dete ction rate will provide unique information about the current star formation rate and the initial mass function. A supernova explosion triggers a shock wave which expels and heats the surrounding CSM and ISM, and forms a supernova remnant (SNR). It is expected that more SNRs will be discovered by the SKA. This may decrease the discrepancy between the expected and observed numbers of SNRs. Several SNRs have been confirmed to accelerate protons , the main component of cosmic rays, to very high energy by their shocks. This brings us hope of solving the Galactic cosmic ray origin’s puzzle by combining the low frequency (SKA) and very high frequency (Cherenkov Telescope Array: CTA) bands’ observations of SNRs.