Complex spectral variability from intensive multiwavelength monitoring of markarian 421 in 1998

T. Takahashi*, J. Kataoka, G. Madejski, J. Mattox, C. M. Urry, S. Wagner, F. Aharonian, M. Catanese, L. Chiappetti, P. Coppi, B. Degrange, G. Fossati, H. Kubo, H. Krawczynski, F. Makino, H. Marshall, L. Maraschi, F. Piron, R. Remillard, F. TakaharaM. Tashiro, H. Terasranta, T. Weekes


研究成果: Article査読

95 被引用数 (Scopus)


We conducted a multifrequency campaign for the TeV blazar Markarian 421 in 1998 April. The campaign started from a pronounced high-amplitude flare recorded by BeppoSAX and Whipple; the ASCA observation started 3 days later. In the X-ray data, we detected multiple flares, occurring on timescales of about 1 day. ASCA data clearly reveal spectral variability. The comparison of the data from ASCA, the Extreme Ultraviolet Explorer, and the Rossi X-Ray Timing Explorer indicates that the variability amplitudes in the low-energy synchrotron component are larger at higher photon energies. In TeV γ-rays, large intraday variations - which were correlated with the X-ray flux - were observed when results from three Cerenkov telescopes were combined. The rms variability of TeV γ-rays was similar to that observed in hard X-rays, above 10 keV. The X-ray light curve reveals flares that are almost symmetric for most cases, implying that the dominant timescale is the light crossing time through the emitting region. The structure function analysis based on the continuous X-ray light curve of 7 days indicates that the characteristic timescale is ∼0.5 days. The analysis of ASCA light curves in various energy bands appears to show both soft (positive) and hard (negative) lags. These may not be real, as systematic effects could also produce these lags, which are all much smaller than an orbit. If the lags of both signs are real, these imply that the particle acceleration and X-ray cooling timescales are similar.

ジャーナルAstrophysical Journal
2 PART 2
出版ステータスPublished - 2000 10月 20

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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