X-ray Emission of Mkn 421: New Clues From Its Spectral Evolution. II. Spectral Analysis and Physical Constraints

Abstract

Mkn 421 was repeatedly observed with BeppoSAX in 1997-1998. The source showed a very rich phenomenology, with remarkable spectral variability. This is the second of two papers presenting the results of a thorough temporal and spectral analysis of all the data available to us, focusing in particular on the flare of April 1998, which was simultaneously observed also at TeV energies. The spectral analysis and correlations are presented in this paper, while the data reduction and timing analysis are the content of the companion paper. The spectral evolution during the flare has been followed over few ks intervals, allowing us to detect for the first time the peak of the synchrotron component shifting to higher energies during the rising phase, and then receding. This spectral analysis nicely confirms the delay of the flare at the higher energies, which in Paper I we quantified as a hard lag of a few ks. Furthermore, at the highest energies, evidence is found of variations of the inverse Compton component. The spectral and temporal information obtained challenge the simplest models currently adopted for the (synchrotron) emission and most importantly provide clues on the particle acceleration process. A scenario accounting for all the observational constraints is discussed, where electrons are injected at progressively higher energies during the development of the flare, and the achromatic decay is ascribed to the source light crossing time exceeding the particle cooling timescales.

arXiv commentAccepted for publication in The Astrophysical Journal. 14 pages, LaTeX using emulateapj, onecolfloat and apsfonts, 9 PostScript figures, 6 Tables

References in corpus (16)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• A Unifying View of the Spectral Energy Distributions of Blazars
• A theoretical unifying scheme for gamma-ray bright blazars
• The Connection between X-ray- and Radio-Selected BL Lacertae Objects
• Constraints on the Physical Parameters of TeV Blazars
• BeppoSAX Observations of Unprecedented Synchrotron Activity in the BL Lac Object Mkn 501
• Rapid variability in the synchrotron self Compton model for blazars
• Ultraviolet and Multiwavelength Variability of the Blazar 3C 279: Evidence for Thermal Emission
• Rapid X-ray Variability of the BL Lacertae Object PKS 2155-304
• Spectral Evolution of PKS 2155-304 observed with BeppoSAX during an Active Gamma-ray Phase
• ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)
• Modeling the variability of the BL Lacertae object PKS 2155-304
• A Rapid X-ray Flare from Markarian 501
• The 0.1-100 keV spectral shape and variability of Mkn421 in high state
• BeppoSAX Observations of the TeV Blazar Mkn 421
• Scientific Report on Low Energy Absorption Features Detected by BeppoSAX LECS in Bright Blazar Targets

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