On the reliability of peak-flux distributions, with an application to solar flares

¹ Sect. of Astrophysics, Astronomy and Mechanics, Dept. of Physics, University of Thessaloniki, 540 06 Thessaloniki, Greece
² Institute of Astronomy, ETH Zentrum, 8092 Zurich, Switzerland

Corresponding author: H. Isliker, isliker@helios.astro.auth.gr

Received: 11 May 2001
Accepted: 8 June 2001

Abstract

Narrow-band radio spikes have been recorded during a solar flare with unprecedented resolution. This unique example allows us to study the effect of low resolution in previously published peak-flux distributions of radio spikes. We give a general, analytical expression for how an actual peak-flux distribution is changed in shape if the peaks are determined with low temporal and/or frequency resolution. It turns out that, generally, low resolution tends to cause an exponential behavior at large flux values if the actual distribution is of a power-law shape. The distribution may be severely altered if the burst-duration depends on the peak-flux. The derived expression is applicable also to peak-flux distributions derived at other wavelengths (e.g. soft and hard X-rays, EUV). We show that for the analyzed spike-event the resolution was sufficient for a reliable peak flux distribution. It can be fitted by generalized power-laws or by an exponential.