1999/06/30 by Michael A. Nowak, James Chiang
Physics and Astronomy · #Active galactic nucleus #Amplitude #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Black hole (networking) #Cosmology #Galaxies: Formation, Evolution, Phenomena #Galaxy #Power law #Spectral density #Spectral line #Supermassive black hole #astro-ph
paper · pdf · doi:10.1086/312508
5 pages, 3 figures, LaTeX, uses emulateapj.sty and apjfonts.sty, revised version, accepted for publication in ApJ Letters
arxiv created 2000/01/14 · openalex publication_date 2000/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The bright Seyfert 1 galaxy MCG -6-30-15 shows large variability on a variety of timescales. We study the less, similar3 day timescale variability using a set of simultaneous archival observations that were obtained from the Rossi X-Ray Timing Explorer (RXTE) and the Advanced Satellite for Cosmology and Astrophysics (ASCA). The RXTE observations span nearly 106 s and indicate that the X-ray Fourier power spectral density has an rms variability of 16%, is flat from approximately 10-6 to 10-5 Hz, and then steepens into a power law proportional to f-alpha with alpha greater, similar1. A further steepening to alpha approximately 2 occurs between 10-4 and 10-3 Hz. The shape and rms amplitude are comparable to what has been observed in NGC 5548 and Cyg X-1, albeit with break frequencies that differ by a factor of 10-2 and 104, respectively. If the break frequencies are indicative of the central black hole mass, then this mass may be as low as 106 M middle dot in circle. An upper limit of approximately 2 ks for the relative lag between the 0.5-2 keV ASCA band compared to the 8-15 keV RXTE band was also found. Again by analogy with NGC 5548 and Cyg X-1, this limit is consistent with a relatively low central black hole mass.