The 5 GHz Arecibo Search for Radio Flares from Ultracool Dwarfs

Abstract

We present the results of a 4.75 GHz survey of 33 brown dwarfs and one young exoplanetary system for flaring radio emission, conducted with the 305-m Arecibo radio telescope. The goal of this program was to detect and characterize the magnetic fields of objects cooler than spectral type L3.5, the coolest brown dwarf detected prior to our survey. We have also attempted to detect flaring radio emission from the HR 8799 planetary system, guided by theoretical work indicating that hot, massive exoplanets may have strong magnetic fields capable of generating radio emission at GHz frequencies. We have detected and confirmed radio flares from the T6.5 dwarf 2MASS J10475385+2124234. This detection dramatically extends the temperature range over which brown dwarfs appear to be at least sporadic radio-emitters, from ~1900 K (L3.5) down to ~900 K (T6.5). It also demonstrates that the utility of radio detection as a unique tool to study the magnetic fields of substellar objects extends to the coolest dwarfs, and, plausibly to hot, massive exoplanets. We have also identified a single, 3.6 sigma flare from the L1 dwarf, 2MASS J1439284+192915. This detection is tentative and requires confirmation by additional monitoring observations.

Accepted for publication in ApJ

References in corpus (24)

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• Looking for a Pulse: A search for Rotationally Modulated Radio Emission from the Hot Jupiter, Tau Bootis b
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• Volume-limited radio survey of ultracool dwarfs
• Discovery of Radio Emission from the Tight M8 Binary: LP 349-25
• A Mini-survey of Ultracool Dwarfs at 4.9 GHz
• Quasi-Quiescent Radio Emission from the First Radio-Emitting T Dwarf
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Cited by in corpus (28)

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• A Panchromatic View of Brown Dwarf Aurorae
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• Radio Flaring from the T6 Dwarf WISEPC J112254.73+255021.5 with A Possible Ultra-short Periodicity
• The detection of variable radio emission from the fast rotating magnetic hot B-star HR7355 and evidence for its X-ray aurorae
• Variable and polarized radio emission from the T6 brown dwarf WISEP J112254.73+255021.5
• 3D-modelling of the stellar auroral radio emission
• Radio detections of southern ultracool dwarfs
• The Second Arecibo Search for 5 GHz Radio Flares from Ultracool Dwarfs
• Ionisation in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events
• The Discovery of Solar-like Activity Cycles Beyond the End of the Main Sequence?
• Timing Analysis of the Periodic Radio and Optical Brightness Variations of the Ultracool Dwarf, TVLM 513-46546
• The Rise of ROME. I. A Multiwavelength Analysis of the Star-Planet Interaction in the HD 189733 System
• Radio-flaring Ultracool Dwarf Population Synthesis
• On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
• A Pilot Radio Search for Magnetic Activity in Directly Imaged Exoplanets
• A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs
• Probing the magnetosphere of the M8.5 dwarf TVLM513-46546 by modelling its auroral radio emission. Hint of star exoplanet interaction?
• Radio emission in ultracool dwarfs: the nearby substellar triple system VHS 1256$-$1257
• Search for exoplanets and brown dwarfs with VLBI
• The Occurrence Rate of Quiescent Radio Emission for Ultracool Dwarfs using a Generalized Semi-Analytical Bayesian Framework
• The milliarcsecond-scale radio structure of AB Dor A
• ROME III. The Arecibo Search for Star-Planet Interactions at 5 GHz
• The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey
• ROME IV. The Arecibo Search for Substellar Magnetospheric Radio Emissions in Purported Exoplanet-Hosting Systems at 5 GHz
• The Decline and Fall of ROME. V. A Preliminary Search for Star-Disrupted Planet Interactions and Coronal Activity at 5 GHz Among White Dwarfs within 25 pc
• Orbital motion and dynamical mass of the complex periodic variable binary system 2MASS J05082729-2101444