Eur. Phys. J. C (2018) 78: 858
https://doi.org/10.1140/epjc/s10052-018-6352-5

Regular Article - Theoretical Physics

Greybody factors and quasinormal modes for a nonminimally coupled scalar field in a cloud of strings in (2 + 1)-dimensional background

¹ Instituto de Física, Pontificia Católica Universidad de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile
² Centro de Astrofísica e Gravitação, Departamento de Física, Instituto Superior Técnico-IST, Universidade de Lisboa-UL, Av. Rovisco Pais, 1049-001, Lisboa, Portugal

^* e-mail: grigorios.panotopoulos@tecnico.ulisboa.pt

Received: 24 August 2018
Accepted: 16 October 2018
Published online: 25 October 2018

Abstract

We study the propagation of a probe massless nonminimally coupled scalar field in a fixed gravitational background of a cloud of strings in (2 + 1) dimensions. We obtain exact analytical expressions for the reflection coefficient, the absorption cross section, the decay rate as well as the quasinormal frequencies. The impact of the nonminimal coupling is investigated in detail. Our results show that universality is not respected in general, and that scalar perturbations are stable.