A dynamically-packed planetary system around GJ 667C with ... - ESO

Guillem Anglada-Escudé et al.: Three HZ super-Earths in a seven-planet system
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Fig. 8. Same as 7 but using the first 100 epochs (left), first 120 (center) and all of them (right).
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Fig. 9. Periodograms on first and second half of the time series as obtained when all signals except one were removed from the data. Except
for signal h, all signals are significantly present in both halves and could have been recovered using either half if they had been in single planet
systems.
amplitudes – except perhaps candidate b which has a considerably
higher amplitude – made this problem especially severe. In
this sense, the currently available set of observation are a sub–
sample of the many more that might be obtained in the future,
so it might happen that one of the signals we report “bifurcates”
into other periodicities. This experiment also suggests that spectral
information beyond the most trivial aliases can be used to
verify and assess the significance of future detections (under investigation).
7.1. Presence of individual signals in one half of the data
As an additional verification against quasi-periodicity, we investigated
if the signals were present in the data when it was divided
in two halves. First half corresponds to the first 86 HARPS observations
and the second half covers the rest. The data from PFS
and HIRES was not used for this test. The experiment consists in
removing all signals except for one of them at a time and compute
the periodogram on those residuals (first and second halfs
separately). If a signal is strongly present in both halfs, it should,
at least, emerge as substantially significant. All signals except for
the seventh one passed this test nicely. That is, in all cases except
for h, the periodograms prominently display the non-removed
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