Validation of Two Earth-mass Planets Orbiting GJ 1002

Abstract GJ 1002 is reported to host two Earth-mass planets in the habitable zone. We applied frequency-domain techniques for validating planet discoveries to the ESPRESSO and CARMENES radial velocity (RV) and cross-correlation full width at half maximum time series. Siegel’s test applied to Welch’s power spectrum estimates suggests that periodicity in the RV time series may not be statistically significant. The frequency response to a sinusoid with the frequency of planet b, or pseudowindow, shows excess power near the frequency of planet c. Finally, a Monte Carlo experiment where we create new RV time series realizations by adding white noise to original data reveals that the highest periodogram peak sometimes occurs at half the frequency of planet c. More extreme-precision observations are required to confirm RV oscillations and constrain the rotation period.