Time series analysis in Astronomy: limits and potentialities

Abstract

In this paper we consider the problem of the limits concerning the physical information that can be extracted from the analysis of one or more time series (light curves) typical of astrophysical objects. On the basis of theoretical considerations and numerical simulations, we show that with no a priori physical model there are not so many possibilities to obtain interpretable results. For this reason, the practice to develop more and more sophisticated statistical methods of time series analysis is not very productive. Only techniques of data analysis developed in a specific physical context can be expected to provide useful results. The field of {\it stochastic dynamics} appears to be an useful framework for such an approach. In particular, it is shown that modelling the experimental time series by means of the stochastic differential equations (SDE) represents a valuable tool of analysis. For example, the use of SDE permits to make the analysis of a continuous signal independent from the frequency sampling with which the experimental time series have been obtained. In this respect, an efficient approach based on the extended Kalman-filter technique is presented. Freely downloadable software is made available.