Investigating the mass of the intermediate mass black hole candidate HLX-1 with the slimbh model

¹ Laboratoire Univers et Théories, CNRS UMR 8102, Observatoire de Paris, Université Paris Diderot, 5 Place Jules Janssen, 92195 Meudon, France
² Institut de Recherche en Astrophysique and Planétologie (IRAP), Université de Toulouse, UPS, 9 Avenue du colonel Roche, 31028 Toulouse Cedex 4, France
e-mail: odele.straub@obspm.fr
³ CNRS, UMR 5277, 31028 Toulouse, France
⁴ Laboratoire AIM, CEA Saclay, Bat. 709, 91191 Gif-sur-Yvette, France

Received: 24 March 2014
Accepted: 14 July 2014

Abstract

In this paper we present a comprehensive study of the mass of the intermediate mass black hole candidate HLX-1 in the galaxy ESO 243-49. We analyse the continuum X-ray spectra collected by Swift, XMM-Newton, and Chandra with the slim disc model, slimbh, and estimate the black hole mass for the full range of inclination (inc = 0°−85°) and spin (a_∗ = 0−0.998). The relativistic slimbh model is particularly suited to study high luminosity disc spectra as it incorporates the effects of advection, such as the shift of the inner disc edge towards smaller radii and the increasing height of the disc photosphere (including relativistic ray-tracing from its proper location rather than the mid-plane of the disc). We find for increasing values of inclination that a zero spin black hole has a mass range of 6300−50 900 M_⊙ and a maximally spinning black hole has a mass between 16 900−191 700 M_⊙. This is consistent with previous estimates and reinforces the idea that HLX-1 contains an intermediate mass black hole.