EDP Sciences
Free Access
Volume 382, Number 1, January IV 2002
Page(s) L1 - L4
Section Letters
DOI https://doi.org/10.1051/0004-6361:20011763

A&A 382, L1-L4 (2002)
DOI: 10.1051/0004-6361:20011763


Detection of a high frequency break in the X-ray power spectrum of Ark 564

I. E. Papadakis1, 2, W. Brinkmann3, H. Negoro4 and M. Gliozzi3

1  IESL, Foundation for Research and Technology-Hellas, PO Box 1527, 711 10 Heraklion, Crete, Greece
2  Physics Department, University of Crete, PO Box 2208, 710 03 Heraklion, Greece
3  Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85740 Garching, Germany
4  Cosmic Radiation Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-01, Japan

(Received 22 October 2001 / Accepted 10 December 2001 )

We present a power spectrum analysis of the long ASCA observation of in June/July 2001. The observed power spectrum covers a frequency range of ~3.5 decades. We detect a high frequency break at ~ $2\times
10^{-3}$  Hz. The power spectrum has an rms of ~30% and a slope of ~-1 and ~-2 below and above the break frequency. When combined with the results from a long RXTE observation (Pounds et al. 2001), the observed power spectra of and Cyg X-1 (in the low/hard state) are almost identical, showing a similar shape and rms amplitude. However, the ratio of the high frequency breaks is very small (~ 103-4), implying that these characteristic frequencies are not indicative of the black hole mass. This result supports the idea of a small black hole mass/high accretion rate in .

Key words: galaxies: active -- galaxies: Seyfert -- galaxies: individual: Ark 564 -- X-rays: galaxies

Offprint request: I. E. Papadakis, jhep@physics.uoc.gr

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© ESO 2002

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