1999/02/28 by W. Bednarek, R. J. Protheroe · 2 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1999.02812.x
18 pages, 5 figures, minor changes, additional reference, accepted for publication in MNRAS
arxiv created 1999/05/24 · openalex publication_date 1999/12/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We determine the physical parameters (magnetic field and Doppler factor) of the homogeneous synchrotron self-Compton model allowed by the observed X-ray to gamma-ray spectra and variability of Markarian 501 during the 1997 April 15–16 flaring activity. We find that magnetic fields between 0.07 and 0.6 G and Doppler factors between 12 and 36 could fit (depending on observed variability time-scale) these observations. We take account of photon-photon pair production interactions of gamma-ray photons occurring both inside the emission region and during propagation to Earth, and find these to be extremely important in correctly determining the allowed model parameters. Previous estimates of the allowed parameter space have neglected this effect. Future multiwavelength campaigns during strong flaring activity, including observations from optical to TeV gamma-rays, should enable the physical parameters to be further constrained.