Validation of Two Earth-mass planets orbiting GJ 1002

GJ 1002, an M dwarf at a distance of 4.84 pc, is reported to host two Earth-mass planets in the habitable zone (Suarez Mascareño et al. 2023). We used the ESPRESSO and CARMENES radial velocity (RV) and cross-correlation full width at half maximum (FWHM) time series in order to test our statistical techniques for validating planet detections. Siegel's test for compound periodicity applied to a Welch's power spectrum estimate suggests that the RV time series is not unambiguously periodic. The frequency response to a sinusoid with the period of planet b, called the pseudowindow, has excess power at the frequency of planet c. The likelihood ratio test and the Bayesian Information Criterion show that the published model, which includes two Keplerians plus a Gaussian process for stellar activity, is not as good a fit to the combined RV-FWHM data as a model with the planets restricted to circular orbits. This study contributes to the debate on the existence of GJ 1002 b and c and showcases new methods for verifying planet orbits.