X iv : a st ro - p h / 99 02 22 4 v 1 1 6 Fe b 19 99 Correlated variability of Mkn 421 at X - ray and TeV wavelengths on timescales of hours

ar X iv : a st ro - p h / 99 10 53 6 v 1 2 9 O ct 1 99 9 Effect of intergalactic absorption in the TeV γ - ray spectrum of Mkn 501

We discuss an effect of the intergalactic absorption of the TeV γ-rays in time-averaged spectrum of Mkn 501 measured by the HEGRA collaboration. Analysis of the spectral behavior, variability time scale and relevant calculations of TeV γ-ray emission allow to conclude the presence of a noticeable absorption of the TeV γ-rays in the Mkn 501 energy spectrum.

ar X iv : a st ro - p h / 99 02 23 4 v 2 1 7 Fe b 19 99 OB ASSOCIATIONS

X iv : a st ro - p h / 97 08 16 2 v 2 1 8 D ec 1 99 7 CONSTRAINTS ON THE EXTRAGALACTIC INFRARED BACKGROUND FROM GAMMA - RAY OBSERVATIONS OF MKN 501

We use the new results of the HEGRA detector on the TeV γ–ray emission from MKN 501 to set upper limits on the energy density of the cosmic infrared background (CIRB). Contrary to previous interpretations of the γ–ray spectrum of MKN 421 as showing an intergalactic absorption cutoff at 5 TeV, the observed spectrum of MKN 501 extends beyond 10 TeV and appears to be unattenuated by γγ collisions ...

Correlated variability of Mkn 421 at X-ray and TeV wavelengths on time scales of hours

Mkn 421 was observed for about two days with BeppoSAX, prior to and partly overlapping the start of a 1 week continuous exposure with ASCA in April 1998, as part of a world-wide multiwavelength campaign. A pronounced, welldefined flare observed in X-rays was also observed simultaneously at TeV energies by the Whipple Observatory’s 10 m gamma-ray telescope. These data provide the first evidence ...

ar X iv : a st ro - p h / 04 12 22 6 v 1 9 D ec 2 00 4 X - RAY FLARES FROM MARKARIAN 501

Motivated by the recent finding of hierarchical X-ray flaring phenomenon in Mrk 421, we conducted a systematic search for X-ray flares from Mrk 501, another well-known TeV blazar, by making use of the rich RXTE archival database. We detected flares over a wide range of timescales, from months down to minutes, as in the case of Mrk 421. However, the flares do not seem to occur nearly as frequent...