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Seminars at FGG

Detection and Orbital Architecture Characterization of Planetary Systems Around Cool Stars

Speaker: Matteo Pinamonti (Universita di Trieste, Italia)

Date and time: 2017-02-23 11:30

The growing evidence from transit and radial velocity surveys points towards a high occurrence rate of low-mass, small-size planets, with a large fraction of late-type M dwarfs hosting habitable-zone terrestrial-type companions, often found in multiple systems, tightly packed close to the central star. In the search for low-mass planets with spectroscopic surveys, the first step in the investigation of unevenly spaced RV time series relies on the identification of statistically significant periodic signals via a variety of implementations of a periodogram analysis. We carried out a comparative analysis of the performance of three widely used algorithms: the Generalised Lomb-Scargle Periodogram (GLS), its modified version based on Bayesian statistics (BGLS), and the multi-frequency periodogram scheme called FREquency DEComposer (FREDEC). We applied the algorithms to a suite of numerical simulations of (single and multiple) low-amplitude Keplerian RV signals induced by low-mass companions around M-dwarf primaries. Our results reinforced the need for the strengthening and further development of the most aggressive and effective ab initio strategies for the robust identification of low-amplitude planetary signals in RV datasets, as I will confirm showing the preliminary results of our ongoing analysis of a multi-planet double M dwarfs system, from Doppler time series collected with the HARPS-N spectrograph.