# Time Variability of Emission and Electron Acceleration in Blazars

### M. Kusunose

### F. Takahara

### H. Li

## Abstract

Recent observations of blazars by X- and gamma-rays show
that blazars exhibit a strong time variation.
We use the synchrotron-self-Compton (SSC) model
to simulate the time variation of radiation
and electron energy spectra.
We solve the kinetic equations of electrons and photons
simultaneously, including a simple model of electron
acceleration which mimics the shock acceleration;
we assume that electrons are accelerated on a given timescale
t_{acc} in an acceleration region.
Electrons escaping from the acceleration region are
*injected* into a cooling region where
electrons emit radio through very high energy
gamma-rays via SSC. We show the numerical results of
time evolution of the energy spectra of electrons and photons,
when low energy electrons (g ~ 2) are
supplied in the acceleration region and accelerated
up to g ~ 10^{7}. Then gamma-rays up to TeV are emitted
as observed from Mrk 421 and Mrk 501, when the acceleration
timescale is sufficiently short.
This model will be used to analyze acceleration mechanisms
in blazars with the observations of time variation.
Flares are also simulated assuming that t_{acc} is reduced
for a period of time, i.e.,
temporal strong acceleration of electrons.
With this simulation we study the light curves at various energy
bands, which enables us to interpret observed flares
of X- and gamma-rays in terms of electron acceleration and SSC.

File translated from T_{E}X by T_{T}H, version 2.32.

On 16 Jul 1999, 09:18.