Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton

Abstract

We present a comprehensive examination of the X-ray variability of the narrow line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent monitoring observations by RXTE with a >100ks continuous observation by XMM-Newton and so present a powerspectral density (PSD) covering an unprecedented frequency range of over 6.5 decades from <1e-8 to >1e-2 Hz. The combined RXTE and XMM-Newton PSD is a very good match to the PSD of the galactic black hole binary system (GBH) Cyg X-1 when in a `high', rather than `low', state providing the first definite confirmation of an AGN in a `high' state. We find a break in the PSD at a frequency ν_{B}=8e-4 Hz. If ν_{B} scales linearly with mass then, assuming a black hole (BH) mass of 10 M_solar for Cyg X-1, we imply a BH mass of 3e-5 M_solar in NGC4051, which is consistent with the recently reported reverberation mapped value. Hence NGC4051 is emitting at \sim30% L_{Edd}. We note that the higher energy photons lag the lower energy ones and that the lag is greater for variations of longer Fourier period and increases with the energy separation of the bands. Variations in different wavebands are very coherent at long Fourier periods but the coherence decreases at shorter periods and as the energy separation between bands increases. This behaviour is similar to that of GBHs and suggests a radial distribution of frequencies and photon energies with higher energies and higher frequencies being associated with smaller radii [ABRIDGED].

arXiv comment6 pages, 9 figures. Proc. of the meeting: "The Restless High-Energy Universe" (Amsterdam, The Netherlands), E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers Eds

References in corpus (14)

• AGN Black Hole Masses and Bolometric Luminosities
• RXTE Observation of Cygnus X-1: II. Timing Analysis
• Measuring the broadband power spectra of active galactic nuclei with RXTE
• X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180
• On the X-ray time lags in the black hole candidates
• The flux-dependent amplitude of broadband noise variability in X-ray binaries and active galaxies
• Soft state of Cygnus X-1: stable disk and unstable corona
• X-Ray Variability Coherence: How to Compute it, What it Means, and How it Constrains Models of Cyg X-1 and GX 339-4
• X-ray continuum variability of MCG-6-30-15
• A Cutoff in the X-ray Fluctuation Power Density Spectrum of the Seyfert 1 Galaxy NGC 3516
• Frequency-dependent time lags in the X-ray emission of the Seyfert galaxy NGC 7469
• RXTE Observation of Cygnus X-1 In Its High State
• The high frequency power spectrum of Markarian 766
• Detection of a high frequency break in the X-ray power spectrum of Ark 564

Cited by in corpus (6)

• A self-consistent hybrid Comptonization model for broad-band spectra of accreting supermassive black holes
• Tracing the accretion history of supermassive Black Holes through X-ray variability: results from the Chandra Deep Field-South
• Multi-Wavelength Variability. Accretion and Ejection at the Fastest Timescales
• A comprehensive long term study of the radio and X-ray Variability of NGC 4051 Paper II
• "Spoon-feeding" an AGN
• Intra-day variability of three Seyfert Galaxies measured with XMM-Newton