On the Detection of Exomoons Transiting Isolated Planetary-Mass Objects

Abstract

All-sky imaging surveys have identified several dozen isolated planetary-mass objects (IPMOs), far away from any star. Here, we examine the prospects for detecting transiting moons around these objects. We expect transiting moons to be common, occurring around 10-15% of IPMOs, given that close-orbiting moons have a high geometric transit probability and are expected to be a common outcome of giant planet formation. IPMOs offer an advantage over other directly imaged planets in that high-contrast imaging is not necessary to detect the photometric transit signal. For at least 30 (>50%) of the currently known IPMOs, observations of a single transit with the James Webb Space Telescope would have low enough forecasted noise levels to allow for the detection of an Io-like or Titan-like moon. Intrinsic variability of the IPMOs will be an obstacle. Using archival time-series photometry of IPMOs with the Spitzer Space Telescope as a proof-of-concept, we found evidence for a fading event of 2MASS J1119-1137 AB that might have been caused by intrinsic variability, but is also consistent with a single transit of a habitable-zone 1.7$R_{\oplus }$ exomoon. Although the interpretation of this particular event is inconclusive, the characteristics of the data and the candidate signal suggest that Earth-sized habitable-zone exomoons around IPMOs are detectable with existing instrumentation.

Accepted to ApJ Letters

References in corpus (51)

• The NumPy array: a structure for efficient numerical computation
• The Transiting Exoplanet Survey Satellite
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• A Circumplanetary Disk Around PDS70c
• A Study of the Shortest-Period Planets Found With Kepler
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• The Planetary Mass Companion 2MASS1207-3932 B: Temperature, Mass and Evidence for an Edge-On Disk
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• HD 203030B: an Unusually Cool Young Sub-Stellar Companion near the L/T Transition
• Formation, Habitability, and Detection of Extrasolar Moons
• Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons?
• HEK VI: On the Dearth of Galilean Analogs in Kepler and the Exomoon Candidate Kepler-1625b I
• Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer
• A Volume-Limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
• The Viewing Geometry of Brown Dwarfs Influences Their Observed Colours and Variability Properties
• Detecting companions to extrasolar planets using mutual events
• The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT
• No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System
• Atmospheric circulation of brown dwarfs and directly imaged exoplanets driven by cloud radiative feedback: global and equatorial dynamics
• On the detection of Exomoons: A search in Kepler data for the orbital sampling effect and the scatter peak
• Spitzer Variability Properties of Low-Gravity L Dwarfs
• Hydrodynamic simulations of captured protoatmospheres around Earth-like planets
• The Young L Dwarf 2MASS J11193254-1137466 is a Planetary-Mass Binary
• Variability of the Lowest Mass Objects in the AB Doradus Moving Group
• Ground-based K-band detection of thermal emission from the exoplanet TrES-3b
• Strong Near-Infrared Spectral Variability of the Young Cloudy L Dwarf Companion VHS J1256-1257 b
• Transit of Exomoon Plasma Tori: New Diagnosis
• Formation of moon systems around giant planets: Capture and ablation of planetesimals as foundation for a pebble accretion scenario
• To cool is to keep: Residual H/He atmospheres of super-Earths and sub-Neptunes
• Alkaline Exospheres of Exoplanet Systems: Evaporative Transmission Spectra
• TESS Observations of the Luhman 16AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation
• Constraining the entropy of formation from young transiting planets
• Observed Variability at 1um and 4um in the Y0 Brown Dwarf WISEP J173835.52+273258.9
• The Hawaii Infrared Parallax Program. V. New T-Dwarf Members and Candidate Members of Nearby Young Moving Groups
• Photometric Monitoring of the Coldest Known Brown Dwarf with the Spitzer Space Telescope
• Cloud Atlas: Rotational Spectral Modulations and potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C
• Innocent Bystanders: Orbital Dynamics of Exomoons during Planet-Planet Scattering
• Brown Dwarf Binaries from Disintegrating Triple Systems
• Conditions for water ice lines and Mars-mass exomoons around accreting super-Jovian planets at 1 - 20 AU from Sun-like stars
• A High-Contrast Search for Variability in HR 8799bc with VLT-SPHERE
• WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object
• Cloud Atlas: Weak color modulations due to rotation in the planetary-mass companion GU Psc b and 11 other brown dwarfs
• Spin-orbit alignment of the $\beta$ Pictoris planetary system
• Rotational Light Curves of Jupiter from UV to Mid-Infrared and Implications for Brown Dwarfs and Exoplanets
• The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B
• A Transient Transit Signature Associated with the Young Star RIK-210
• Presence of water on exomoons orbiting free-floating planets: a case study
• A search for photometric variability in the young T3.5 planetary-mass companion GU Psc b