Research Note

Modelling the variability of 1ES1218+30.4

Lehrstuhl für Astronomie, University of Würzburg, Am Hubland, 97074 Würzburg, Germany e-mail: fspanier@astro.uni-wuerzburg.de

Received: 22 February 2010
Accepted: 6 April 2010

Abstract

Context. The blazar 1 ES 1218+30.4 has been previously detected by the VERITAS and MAGIC telescopes in the very high energies. The new detection of VERITAS from December 2008 to April 2009 proves that 1 ES 1218+30.4 is not static, but shows short-time variability.

Aims. We show that the time variability may be explained in the context of a self-consistent synchrotron-self Compton model, while the long time observation do not necessarily require a time-resolved treatment.

Methods. The kinetic equations for electrons and photons in a plasma blob are solved numerically including Fermi acceleration for electrons as well as synchrotron radiation and Compton scattering.

Results. The light curve observed by VERITAS can be reproduced in our model by assuming a changing level of electron injection compared to the constant state of 1 ES 1218+30.4. The multiwavelength behaviour during an outburst becomes comprehensible by the model.

Conclusions. The long time measurements of VERITAS are still explainable via a constant emission in the SSC context, but the short outbursts each require a time-resolved treatment.