Radio Supernovae

TL;DR

This paper addresses how radio emission from SN–CSM interactions encodes the pre-explosion mass-loss history of SN progenitors. It integrates the theory of forward/reverse shocks, CSM and ejecta density profiles (e.g., $\rho_{CSM} = A r^{-s}$ and $\rho_{SN} \propto r^{-n}$) with the physics of synchrotron emission and absorption processes to interpret radio light curves across core-collapse and Type Ia SNe, highlighting the roles of SSA and free-free absorption. Key findings show that many core-collapse SNe, especially Type IIn and IIb, exhibit bright, long-lasting radio emission tied to dense CSM, while Type Ia SNe largely lack detections, placing stringent limits on SD channels; SN 2014J provides tight upper limits favoring DD progenitors for that event. The work underscores that upcoming facilities (VLBI, VLASS, ASKAP, SKA, ngVLA) will substantially improve mass-loss reconstructions over wide temporal baselines, enhancing our understanding of SN progenitors and explosion mechanisms, with implications for stellar evolution and cosmology.

Abstract

Supernovae (SNe), the catastrophic end of stars' lives, are among the most energetic phenomena in the universe. Mapping the aftermath of the explosions to the properties of pre-SN stars is challenging due to the lack of knowledge about the evolution of different types of stars. The immediate surroundings of pre-SN stars carry the signature of the progenitors, and radio observations are the best way to examine the ambient media. Since radio emission originates from the interaction of supersonic SN ejecta with the relatively stationary circumstellar medium, with a few years of radio study, the mass-loss history of progenitor stars can be probed from just before the explosion of the star to thousands of years before the onset of the SN. Moreover, this can provide crucial details about the explosions, which are poorly understood to date. In this paper, we review the radio properties of different types of core-collapse explosions and thermonuclear runaways to understand their mass-loss evolution--which allows us to unravel the imprints of the progenitors on the surrounding media and thus the nature of the exploded stars. Additionally, we discuss the current state of the art in this field, including existing and the next-generation radio facilities with enhanced capabilities that provide further details about these explosions.

Figures (29)

• Figure S1: (Left panel): Interaction of SN ejecta with a wind-like ambient medium. The different regions shown here are not to-scale. The contact discontinuity exists between the forward and reverse shocks. Figure reproduced from peter88 with permission. (Right panel): For a wind-like CSM and ejecta with an extreme outer part having a power-law profile with a power-law index of 7, the density, velocity, and pressure profiles are displayed within the shocked shell, which is bounded by the forward and reverse shocks. The contact discontinuity between the two shocks is also depicted here. The X-axis is normalized with respect to the position of the forward shock (which is represented here by $\rm R_1$), and the Y-axis is scaled according to pressure, velocity, and density values just behind the forward shock. Figure reproduced from blondin01 with permission.
• Figure S2: The growth of the RT instability in the shocked ejecta for different effective adiabatic indices, $\gamma_{\rm eff}$, of the gas. This simulation is performed for a wind-like CSM and ejecta with an extreme outer part having a power-law profile with a power-law index of 7. The finger-like structures represent the RT instability with the density color bar scaled with respect to the density of the CSM just ahead of the forward shock. For higher $\gamma_{\rm eff}$, the instability stays close to the reverse shock area, while as $\gamma_{\rm eff}$ decreases, the protrusions spread across the entire shocked region. Figure reproduced from kundu_thesis_2019 with permission.
• Figure S3: SN ejecta profiles, as obtained from STELLA along with the fitted ones, for SN 1993J (left panel) and SN 2011dh (right panel), one day after the explosions. The dotted vertical lines in the ejecta profiles illustrate the reverse shock position at 1000, 2000, 3000, 5000, 7000, and 8000 days after the explosion of SN 1993J and that at 200, 500, and 1200 days after the explosion of SN 2011dh. Figure reproduced from kundu19 with permission.
• Figure S4: Evolution of luminosities of different types of Type II explosions at 4--10 GHz, at a distance of less than 100 Mpc. The light curve of Type IIP SN 1987A is at 2.3 GHz. The continuous lines that connect different measurements of a given explosion represent SNe with multiple detections. The solid circles show single detections, and the triangles represent the upper limits..Figure reproduced from Bietenholz21a with permission.
• Figure S5: Evolution of luminosities of different types of Type IIn explosions at 4--10 GHz, at a distance of less than 100 Mpc. See the caption of Figure \ref{['bitenholz_sn_ii_rad_light_curve']} for the details about lines and symbols used in this diagram. Figure reproduced from Bietenholz21a with permission.