The model constraints from the observed trends for the quasi-periodic oscillation in RE J1034+396

¹ Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warszawa, Poland
e-mail: bcz@camk.edu.pl
² Centre for Wavelets, Approximation and Information Processing, Temasek Laboratories at National University of Singapore, 5A Engineering Drive 1, #09-02, 117411, Singapore, Republic of Singapore
e-mail: pawel@ieee.org
³ Astronomical Institute, Academy of Sciences, Boční II 1401, 14131 Prague, Czech Republic
⁴ Harish Chandra Research Institute, Allahabad 211019, India

Received: 24 November 2009
Accepted: 12 September 2010

Abstract

We analyze the time variability of the X-ray emission of RE J1034+396 – an active galactic nucleus with the first firm detection of a quasi-periodic oscillations (QPO). Based on the results of a wavelet analysis, we find a drift in the QPO central frequency. The change in the QPO frequency correlates with the change in the X-ray flux with a short time delay. The data specifically suggest a linear dependence between the QPO period and the flux, and this gives important constraints on the QPO models. In particular, it excludes explanation in terms of the orbiting hot spot model close to a black hole. Linear structures such as shocks, spiral waves, or very distant flares are favored.