Optimizing the search for transiting planets in long time series⋆
Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
Received: 6 December 2012
Accepted: 9 July 2013
Context. Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years.
Aims. The search for transiting planets in these long time series is computationally intensive. We wish to optimize the search for both detection and computational efficiencies.
Methods. We assume that the searched systems can be described well by Keplerian orbits. We then propagate the effects of different system parameters to the detection parameters.
Results. We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star’s size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually.
Conclusions. By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the BLS parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available.
Key words: methods: data analysis / planets and satellites: detection / planetary systems
The MATLAB code is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A138
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