$\mathtt{KOBEsim}$: a Bayesian observing strategy algorithm for planet detection in radial velocity blind-search surveys

Abstract

Ground-based observing time is precious in the era of exoplanet follow-up and characterization, especially in high-precision radial velocity instruments. Blind-search radial velocity surveys thus require a dedicated observational strategy in order to optimize the observing time, which is particularly crucial for the detection of small rocky worlds at large orbital periods. We develop an algorithm with the purpose of improving the efficiency of radial velocity observations in the context of exoplanet searches, and we apply it to the K-dwarfs Orbited By habitable Exoplanets (KOBE) experiment. We aim at accelerating exoplanet confirmations or, alternatively, rejecting false signals as early as possible in order to save telescope time and increase the efficiency of both blind-search surveys and follow-up of transiting candidates. Once a minimum initial number of radial velocity datapoints is reached in such a way that a periodicity starts to emerge according to generalized Lomb-Scargle (GLS) periodograms, that period is targeted with the proposed algorithm, named $\text{KOBEsim}$. The algorithm selects the next observing date that maximizes the Bayesian evidence for such periodicity in comparison with a model with no Keplerian orbits. By means of simulated data, we prove that the algorithm accelerates the exoplanet detection, needing $29-33\%$ less observations and $41-47\%$ less timespan of the full dataset for low-mass planets ($m_{\mathrm{p}}<10M_{\oplus }$) in comparison with a conventional monotonic cadence strategy. The enhancement in the number of datapoints for $20M_{\oplus }$ planets is also appreciable, $16\%$. We also test $\text{KOBEsim}$ with real data for a particular KOBE target, and for the confirmed planet $HD102365b$. Both of them demonstrate that the strategy is capable of speeding up the detection up to a factor of $2$.

Accepted for publication in A$\&$A: 14 pages, 10 figures, 5 tables. Language corrected

References in corpus (16)

• astroquery: An Astronomical Web-Querying Package in Python
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• ESPRESSO@VLT -- On-sky performance and first results
• Cool Jupiters greatly outnumber their toasty siblings: Occurrence rates from the Anglo-Australian Planet Search
• A candidate short-period sub-Earth orbiting Proxima Centauri
• The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
• Warm terrestrial planet with half the mass of Venus transiting a nearby star
• Planetary system LHS 1140 revisited with ESPRESSO and TESS
• Radial Velocity Data Analysis with Compressed Sensing Techniques
• A precise architecture characterization of the $\pi$ Men planetary system
• K2-111: an old system with two planets in near-resonance
• Variability in stellar granulation and convective blueshift with spectral type and magnetic activity. II. From young to old main-sequence K-G-F stars
• Understanding stellar activity-induced radial velocity jitter using simultaneous K2 photometry and HARPS RV measurements
• The KOBE experiment: K-dwarfs Orbited By habitable Exoplanets. Project goals, target selection and stellar characterization
• HD22496b: the first ESPRESSO standalone planet discovery
• Scheduling strategies for the ESPRESSO follow-up of TESS targets