Parameter Estimation from Time-Series Data with Correlated Errors: A Wavelet-Based Method and its Application to Transit Light Curves

TL;DR

This paper introduces a wavelet-based algorithm for accurate parameter estimation in time-series data with correlated Gaussian noise, demonstrated on exoplanet transit light curves, outperforming existing methods in accuracy and uncertainty estimation.

Contribution

A novel, efficient wavelet-based likelihood method for parameter estimation in correlated noise time-series, specifically applied to exoplanet transit data.

Findings

More accurate midtransit time estimates

Better uncertainty quantification

Outperforms traditional methods in simulations

Abstract

We consider the problem of fitting a parametric model to time-series data that are afflicted by correlated noise. The noise is represented by a sum of two stationary Gaussian processes: one that is uncorrelated in time, and another that has a power spectral density varying as $1/f^\gamma$. We present an accurate and fast [O(N)] algorithm for parameter estimation based on computing the likelihood in a wavelet basis. The method is illustrated and tested using simulated time-series photometry of exoplanetary transits, with particular attention to estimating the midtransit time. We compare our method to two other methods that have been used in the literature, the time-averaging method and the residual-permutation method. For noise processes that obey our assumptions, the algorithm presented here gives more accurate results for midtransit times and truer estimates of their uncertainties.