학술논문
Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability
Document Type
Working Paper
Author
Fossati, G.; Buckley, J. H.; Bond, I. H.; Bradbury, S. M.; Carter-Lewis, D. A.; Chow, Y. C. K.; Cui, W.; Falcone, A. D.; Finley, J. P.; Gaidos, J. A.; Grube, J.; Holder, J.; Horan, D.; Horns, D.; Jordan, M. M.; Kieda, D. B.; Kildea, J.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Lee, K.; Moriarty, P.; Ong, R. A.; Petry, D.; Quinn, J.; Sembroski, G. H.; Wakely, S. P.; Weekes, T. C.
Source
The Astrophysical Journal, 2008, 677, 906-925
Subject
Language
Abstract
(Abridged) We present a detailed analysis of week-long simultaneous observations of the blazar Mrk421 at 2-60 keV X-rays (RXTE) and TeV gamma-rays (Whipple and HEGRA) in 2001. The unprecedented quality of this dataset enables us to establish firmly the existence of the correlation between the TeV and X-ray luminosities, and to start unveiling some of its more detailed characteristics, in particular its energy dependence, and time variability. The source shows strong, highly correlated variations in X-ray and gamma-ray. No evidence of X-ray/gamma-ray interband lag is found on the full week dataset (<3 ks). However, a detailed analysis of the March 19 flare reveals that data are not consistent with the peak of the outburst in the 2-4 keV X-ray and TeV band being simultaneous. We estimate a 2.1+/-0.7 ks TeV lag. The amplitudes of the X-ray and gamma-ray variations are also highly correlated, and the TeV luminosity increases more than linearly w.r.t. the X-ray one. The strong correlation supports the standard model in which a unique electrons population produces the X-rays by synchrotron radiation and the gamma-ray component by inverse Compton scattering. However, for the individual best observed flares the gamma-ray flux scales approximately quadratically w.r.t. the X-ray flux, posing a serious challenge to emission models for TeV blazars. Rather special conditions and/or fine tuning of the temporal evolution of the physical parameters of the emission region are required in order to reproduce the quadratic correlation.
Comment: Correction to authorship. Minor editorial changes to text, figures, references. 22 pages (emulateapj), 12 figures (47 postscript files) Published in ApJ, 2008 April 20 (ADS: 2008ApJ...677..906F)
Comment: Correction to authorship. Minor editorial changes to text, figures, references. 22 pages (emulateapj), 12 figures (47 postscript files) Published in ApJ, 2008 April 20 (ADS: 2008ApJ...677..906F)