A possible interpretation for the apparent differences in LFQPO types in microquasars

¹ APC, AstroParticule & Cosmologie, UMR 7164 CNRS/N2P3, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
e-mail: varniere@apc.univ-paris7.fr
² Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Université d’Orléans/CNRS, Orléans, France
³ Laboratoire AIM, CEA/IRFU-CNRS/INSU-Université Paris Diderot, CEA DSM/IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette, France

Received: 11 February 2011
Accepted: 23 July 2012

Abstract

Aims. In most microquasars, low-frequency quasi-periodic oscillations (LFQPO) have been classified into three types (A, B and C depending on the peak distribution in the power density spectra and the shape of the noise) but no explanationhas been proposed yet. The accretion-ejection instability (AEI) was presented in 1999 as a possible explanation for the fast varying LFQPO that occur most often. Here we look at a possible generalization to explain the characteristics of the other two LFQPO types.

Methods. It was recently shown that when the disk approaches its last stable orbit, the AEI is markedly affected by relativistic effects. We focus on the characteristics of the LFQPO that would result from the relativistic AEI and compare them with the different LFQPO types.

Results. The effects of relativity on the AEI seem to be able to explain most of the characteristics of the three types of LFQPO within one formalism.