The Detectability of Moons of Extra-Solar Planets

TL;DR

This paper investigates the potential for detecting moons around extra-solar planets using time-of-arrival perturbation and photometric transit timing techniques, analyzing thresholds, stability, and applying methods to specific cases like PSR B1620-26 b.

Contribution

It provides new analytic expressions for moon detection signals and noise analysis, extending detection methods to inclined and eccentric orbits, and applies these to real pulsar systems.

Findings

Moons >5% of planet mass could be detectable around PSR B1620-26 b.

Detection thresholds depend on orbital configurations and noise levels.

Analytic models for timing perturbations are developed for various orbital geometries.

Abstract

The detectability of moons of extra-solar planets is investigated, focussing on the time-of-arrival perturbation technique, a method for detecting moons of pulsar planets, and the photometric transit timing technique, a method for detecting moons of transiting planets. Realistic thresholds are derived and analysed in the in the context of the types of moons that are likely to form and be orbitally stable for the lifetime of the system. For the case of the time-of-arrival perturbation technique, the analysis is conducted in two stages. First, a preliminary investigation is conducted assuming that planet and moon's orbit are circular and coplanar. This analysis is then applied to the case of the pulsar planet PSR B1620-26 b, and used to conclude that a stable moon orbiting this pulsar planet could be detected, if its mass was >5% of its planet's mass (2.5 Jupiter masses), and if the planet-moon distance was ~ 2% of the planet-pulsar separation (23 AU). Time-of-arrival expressions are then derived for mutually inclined as well as non-circular orbits. For the case of the photometric transit timing technique, a different approach is adopted. First, analytic expressions for the timing perturbation due to the moon are derived for the case where the orbit of the moon is circular and coplanar with that of the planet and where the planet's orbit is circular and aligned to the line-of-sight, circular and inclined with respect to the line-of-sight or eccentric and aligned to the line-of-sight. Second, the timing noise is investigated analytically, for the case of white photometric noise, and numerically, using SOHO lightcurves, for the case of realistic and filtered realistic photometric noise. [...] Abstract truncated due to the limitations of astroph. See full abstract in the thesis.