The fate of supernova remnants near quiescent supermassive black holes

TL;DR

This paper develops a numerical method to study supernova remnant evolution near quiescent supermassive black holes, revealing how SMBH mass influences SNR shapes, lifetimes, and disruption, with implications for observations in galactic nuclei.

Contribution

A novel numerical approach based on the Kompaneets approximation to model SNR evolution in SMBH environments, accounting for gas gradients and tidal effects.

Findings

SNR disruption occurs faster around SMBHs >10^7 Msun, shortening the X-ray phase.

In the Galactic Centre, SNRs have longer X-ray emitting phases, consistent with observations.

Estimated supernova rate in Sgr A*'s sphere of influence is about one per 10^4 years.

Abstract

There is mounting observational evidence that most galactic nuclei host both supermassive black holes (SMBHs) and young populations of stars. With an abundance of massive stars, core-collapse supernovae are expected in SMBH spheres of influence. We develop a novel numerical method, based on the Kompaneets approximation, to trace supernova remnant (SNR) evolution in these hostile environments, where radial gas gradients and SMBH tides are present. We trace the adiabatic evolution of the SNR shock until 50% of the remnant is either in the radiative phase or is slowed down below the SMBH Keplerian velocity and is sheared apart. In this way, we obtain shapes and lifetimes of SNRs as a function of the explosion distance from the SMBH, the gas density profile and the SMBH mass. As an application, we focus here exclusively on quiescent SMBHs, because their light may not hamper detections of SNRs and because we can take advantage of the unsurpassed detailed observations of our Galactic Centre. Assuming that properties such as gas and stellar content scale appropriately with the SMBH mass, we study SNR evolution around other quiescent SMBHs. We find that, for SMBH masses over ~10^7 Msun, tidal disruption of SNRs can occur at less than 10^4 yr, leading to a shortened X-ray emitting adiabatic phase, and to no radiative phase. On the other hand, only modest disruption is expected in our Galactic Centre for SNRs in their X-ray stage. This is in accordance with estimates of the lifetime of the Sgr A East SNR, which leads us to expect one supernova per 10^4 yr in the sphere of influence of Sgr A*.