Shadow and near-horizon characteristics of the acoustic charged black hole in curved spacetime

TL;DR

This paper investigates the horizon structure, acoustic shadow, quasinormal modes, and analogue Hawking radiation of an acoustic charged black hole in curved spacetime, revealing how charge and tuning parameters influence these properties.

Contribution

It provides the first detailed analysis of the acoustic shadow, QNM frequencies, and Hawking radiation characteristics of an acoustic charged black hole, highlighting differences from astrophysical black holes.

Findings

Acoustic shadow radius is larger than that of Reissner-Nordström black hole.

QNM frequencies indicate stability and are weaker than astrophysical black holes.

Energy emission rate decreases with charge and angular number, influenced by Hawking temperature.

Abstract

In this paper, we first analyze the horizon structure of the acoustic charged black hole in curved spacetime, and then study its acoustic shadow as well as the near-horizon characteristics including the quasinormal modes (QNM) frequencies and analogue Hawking radiation. We find that the radius of the acoustic shadow for acoustic charged black hole is larger than that for Reissner-Nordstr\"{o}m (RN) black hole, and both of them are suppressed by increasing the black hole charge because their related outer horizons become smaller. Then the QNM frequencies under scalar field perturbation and its eikonal limit are computed via numeric method and acoustic shadow, respectively. We find that the acoustic charged black hole is stable under the perturbation and the QNM frequencies are much weaker than that for the astrophysical black hole. Moreover, as the tuning parameter increases, the perturbation oscillates more mildly and its damping time becomes longer, while as the charge increases, the oscillation is enhanced slightly and the perturbation decays a little faster which is different from that in RN black hole. Finally, we numerically study the analogue Hawking radiation. We find that the grey-body factor and energy emission rate are suppressed by the angular number and the charge, but they do not monotonically depend on the tuning parameter in the acoustic charged black hole. The behavior of the energy emission rate affected by the parameters could be explained by the dependent behavior of the Hawking temperature. We expect that our results could shed light to the study of black holes in both theoretical and experimental perspectives.