Thin accretion disks and charged rotating dilaton black holes

Mohaddese Heydari-Fard,Hamid Reza Sepangi,Malihe Heydari-Fard

doi:10.1140/epjc/s10052-020-7911-0

Mohaddese Heydari-Fard, Hamid Reza Sepangi + Show 1 more

Open Access

https://doi.org/10.1140/epjc/s10052-020-7911-0

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Abstract

Einstein-Maxwell-dilaton theory is an interesting theory of gravity for studying scalar fields in the context of no-hair theorem. In this work, we consider static charged dilaton and charged, slowly rotating dilaton black holes in Einstein-Maxwell-dilaton gravity. We investigate the accretion process in thin disks around such black holes, using the Novikov-Thorne model. The electromagnetic flux, temperature distribution, energy conversion efficiency and also innermost stable circular orbits of thin disks are obtained and effects of dilaton and rotation parameters are studied. For the static and slowly rotating black holes the results are compared to that of Schwarzschild and Kerr, respectively.

Highlights

General relativity (GR) is a successful theory for describing various gravitational phenomena from planetary to cosmic scales
String theory somewhat paves the way for quantum gravity by supplementing the usual Einstein-Hilbert action with possible higher-order curvature invariants which result from its low energy limit, together with an additional scalar dilaton field non-minimally coupled to gravity [1]
These considerations have motivated a large number of studies in the past decades in a scenario where a dilaton field is non-minimally coupled to a Maxwell field, known as Einstein-Maxwell-dilaton gravity (EMDG)

Summary

Introduction

General relativity (GR) is a successful theory for describing various gravitational phenomena from planetary to cosmic scales. String theory somewhat paves the way for quantum gravity by supplementing the usual Einstein-Hilbert action with possible higher-order curvature invariants which result from its low energy limit, together with an additional scalar dilaton field non-minimally coupled to gravity [1]. In this paper we consider static and slowly rotating charged dilaton black holes and study the properties of thin accretion disks around them. 3 we introduce static and charged rotating dilaton black holes and derive the effective potential, electromagnetic flux, temperature distribution and energy conversion efficiency of thin disks in the context of EMDG and move on to investigate the effects of dilaton coupling α and rotation parameter a on the disk properties.

Accretion in thin disks around stationary axisymmetric spacetimes

Geometry of space-time and geodesic equations

Electromagnetic properties and structure of thin accretion disks

Charged rotating dilaton black holes

Findings

Conclusions