Precision radial velocity measurements by the forward-modeling technique in the near-infrared

Abstract

Precision radial velocity (RV) measurements in the near-infrared are a powerful tool to detect and characterize exoplanets around low-mass stars or young stars with higher magnetic activity. However, the presence of strong telluric absorption lines and emission lines in the near infrared that significantly vary in time can prevent extraction of RV information from these spectra by classical techniques, which ignore or mask the telluric lines. We present a methodology and pipeline to derive precision RVs from near-infrared spectra using a forward-modeling technique. We applied this to spectra with a wide wavelength coverage (Y, J, and H bands, simultaneously), taken by the InfraRed Doppler (IRD) spectrograph on the Subaru 8.2-m telescope. Our pipeline extracts the instantaneous instrumental profile of the spectrograph for each spectral segment, based on a reference spectrum of the laser-frequency comb that is injected into the spectrograph simultaneously with the stellar light. These profiles are used to derive the intrinsic stellar template spectrum, which is free from instrumental broadening and telluric features, as well as model and fit individual observed spectra in the RV analysis. Implementing a series of numerical simulations using theoretical spectra that mimic IRD data, we test the pipeline and show that IRD can achieve $<2$ m s${}^{-1}$ precision for slowly rotating mid-to-late M dwarfs with a signal-to-noise ratio $>100$ per pixel at 1000 nm. Dependences of RV precision on various stellar parameters (e.g., $T_{\mathrm{eff}}$, $v\sin i$, [Fe/H]) and the impact of telluric-line blendings on the RV accuracy are discussed through the mock spectra analyses. We also apply the RV-analysis pipeline to the observed spectra of GJ 699 and TRAPPIST-1, demonstrating that the spectrograph and the pipeline are capable of an RV accuracy of $<3$ m s${}^{-1}$ at least on a time scale of a few months.

arXiv comment21 pages, 20 figures; accepted for publication in PASJ; typos corrected

References in corpus (30)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample
• Tempo2, a new pulsar timing package. II: The timing model and precision estimates
• The Occurrence Rate of Small Planets around Small Stars
• The CORALIE survey for southern extra-solar planets VII. Two short-period Saturnian companions to HD108147 and HD168746
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• The nature of the TRAPPIST-1 exoplanets
• An atmospheric radiation model for Cerro Paranal. I. The optical spectral range
• A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
• The inner edge of the habitable zone for synchronously rotating planets around low-mass stars using general circulation models
• Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
• An advanced scattered moonlight model for Cerro Paranal
• They are Small Worlds After All: Revised Properties of Kepler M Dwarf Stars and their Planets
• Improved Modeling of the Rossiter-McLaughlin Effect for Transiting Exoplanets
• The CRIRES Search for Planets Around the Lowest-Mass Stars. I. High-Precision Near-Infrared Radial Velocities with an Ammonia Gas Cell
• The HARPS search for southern extra-solar planets XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293
• The Kepler Dichotomy among the M Dwarfs: Half of Systems Contain Five or More Coplanar Planets
• A candidate super-Earth planet orbiting near the snow line of Barnard's star
• A uniform analysis of HD209458b Spitzer/IRAC lightcurves with Gaussian process models
• Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars II: Planetary Systems Observed During Campaigns 1-7
• Accurate M Dwarf Metallicities from Spectral Synthesis: A Critical Test of Model Atmospheres
• Exoplanets around Low-mass Stars Unveiled by K2
• The ExoMol Atlas of Molecular Opacities
• Evidence for Spin-orbit Alignment in the TRAPPIST-1 System
• Modelling telluric line spectra in the optical and infrared with an application to VLT/X-Shooter spectra
• Detecting Planets around Very Cool Dwarfs at Near Infrared Wavelengths with the Radial Velocity Technique
• Global Analysis of KOI-977: Spectroscopy, Asteroseismology, and Phase-curve Analysis
• Bayesian least squares deconvolution

Cited by in corpus (35)

• First Detection of Hydroxyl Radical Emission from an Exoplanet Atmosphere: High-dispersion Characterization of WASP-33b using Subaru/IRD
• Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
• Two temperate super-Earths transiting a nearby late-type M dwarf
• TOI-1452 b: SPIRou and TESS reveal a super-Earth in a temperate orbit transiting an M4 dwarf
• Statistical methods for exoplanet detection with radial velocities
• Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)
• Ultraviolet astronomical spectrograph calibration with laser frequency combs from nanophotonic lithium niobate waveguides
• Elemental abundances of nearby M dwarfs based on high-resolution near-infrared spectra obtained by the Subaru/IRD survey: Proof of concept
• High-Resolution Transmission Spectroscopy of the Terrestrial Exoplanet GJ 486b
• An M dwarf accompanied by a close-in giant orbiter with SPECULOOS
• The mass determination of TOI-519 b: a close-in giant planet transiting a metal-rich mid-M dwarf
• Zodiacal Exoplanets in Time (ZEIT) XIII: Planet Orbits and Atmospheres in the V1298 Tau System, a Keystone in Studies of Early Planetary Evolution
• Characterization of the ESPRESSO Line-Spread Function and Improvement of the Wavelength Calibration Accuracy
• Gliese 12 b: A temperate Earth-sized planet at 12 pc ideal for atmospheric transmission spectroscopy
• Planet(esimal)s Around Stars with TESS (PAST) III: A Search for Triplet He I in the Atmospheres of Two 200 Myr-old Planets
• TOI-1696: a nearby M4 dwarf with a $3R_{\oplus }$ planet in the Neptunian desert
• TOI-2285b: A 1.7 Earth-radius Planet Near the Habitable Zone around a Nearby M Dwarf
• A Super-Earth Orbiting Near the Inner Edge of the Habitable Zone around the M4.5-dwarf Ross 508
• Absence of extended atmospheres in low-mass star radius-gap planets GJ 9827 b, GJ 9827 d and TOI-1235 b
• Validation and atmospheric exploration of the sub-Neptune TOI-2136b around a nearby M3 dwarf
• TOI-1442 b and TOI-2445 b: two potentially rocky ultra-short period planets around M dwarfs
• Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988. A CARMENES and IRD collaboration
• Zodiacal Exoplanets in Time (ZEIT) XII: A Directly-Imaged Planetary-Mass Companion to a Young Taurus M Dwarf Star
• An Earth-sized Planet around an M5 Dwarf Star at 22 pc
• viper: High-precision radial velocities from the optical to the infrared (Reaching 3 m/s in the K band of CRIRES+ with telluric modelling)
• Direct Imaging Explorations for Companions around Mid-Late M Stars from the Subaru/IRD Strategic Program
• Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B
• The SPIRou Legacy Survey: near-infrared and optical radial velocity analysis of Gl 480 and Gl 382 using SPIRou, HARPS and CARMENES spectrographs
• Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions
• The SPIRou Legacy Survey: Detection of a nearby world orbiting in the habitable zone of Gl725B achieved by correcting strong telluric contamination in near-infrared radial velocities with WAPITI
• A Search for helium in the atmospheres of three sub-Neptunes and a super-Earth around M-dwarfs
• Silicon and Strontium abundances of very metal-poor stars determined from near-infrared spectra
• Non-detection of Helium in the upper atmospheres of TRAPPIST-1b, e and f
• Sibling Sub-Neptunes Around Sibling M Dwarfs: TOI-521 and TOI-912
• Characterizing the Instrumental Profile of LAMOST