Population Study of Astrophysical False Positive Detections in the Southern PLATO field

TL;DR

This study assesses false positive rates in the upcoming PLATO mission's southern and northern fields, finding low FP rates for small planets in the south but higher rates at low galactic latitudes in the north, informing target selection.

Contribution

It provides a synthetic population analysis of astrophysical false positives for the PLATO mission's southern and northern fields, highlighting spatial variations and implications for planet detection.

Findings

Low FP rate for planets smaller than Neptunes in southern field

FP rate increases at lower galactic latitudes, especially in northern field

Approximately twice the FP percentage in northern field segment compared to southern

Abstract

For the upcoming PLAnetary Transits and Oscillation of stars (PLATO) satellite mission, a large number of target stars are required to yield a statistically significant number of planet transits. Locating the centres of the long duration observational phase (LOP) fields closer to the Galactic plane will increase the target star numbers but also the astrophysical false positives (FPs) from blended eclipsing binary systems. We utilise the Binary Stellar Evolution and Population Synthesis (BiSEPS) code, to create a complete synthetic stellar and planetary population for the proposed southern LOP field (LOPS0), as well as for a representative portion of the northern LOP field (LOPNsub). For LOPS0 we find an overall low FP rate for planets smaller than Neptunes. The FP rate generally shows little variation with Galactic longitude (l), and a modest increase with decreasing Galactic latitude (|b|). The location of the LOPS field centre within the current allowed region is not strongly constrained by FPs. Analysis of LOPNsub suggests a markedly increased number of FPs across the full range of planet radii at low |b| resulting in approximately twice the percent FP rate in the LOPNsub compared to the corresponding southern field segment in the planet radius range -0.2 < log(R/Rsun) <= 0.4. However, only a few percent of fully eclipsing FPs in LOPS0 in this radius range have periods