Testing protoplanetary disc dispersal with radio emission

Abstract

We consider continuum free-free radio emission from the upper atmosphere of protoplanetary discs as a probe of the ionized luminosity impinging upon the disc. Making use of previously computed hydrodynamic models of disc photoevaporation within the framework of EUV and X-ray irradiation, we use radiative transfer post-processing techniques to predict the expected free-free emission from protoplanetary discs. In general, the free-free luminosity scales roughly linearly with ionizing luminosity in both EUV and X-ray driven scenarios, where the emission dominates over the dust tail of the disc and is partial optically thin at cm wavelengths. We perform a test observation of GM Aur at 14-18 Ghz and detect an excess of radio emission above the dust tail to a very high level of confidence. The observed flux density and spectral index are consistent with free-free emission from the ionized disc in either the EUV or X-ray driven scenario. Finally, we suggest a possible route to testing the EUV and X-ray driven dispersal model of protoplanetary discs, by combining observed free-free flux densities with measurements of mass-accretion rates. On the point of disc dispersal one would expect to find a M_dot^2 scaling with free-free flux in the case of EUV driven disc dispersal or a M_dot scaling in the case of X-ray driven disc dispersal.

Accepted MNRAS, 12 pages, 11 figures, (pdf generation fixed)

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Cited by in corpus (14)

• How drifting and evaporating pebbles shape giant planets I: Heavy element content and atmospheric C/O
• Distribution of solids in the rings of the HD 163296 disk: a multiwavelength study
• Disk Dispersal: Theoretical Understanding and Observational Constraints
• Low EUV Luminosities Impinging on Protoplanetary Disks
• Characterization of Ring Substructures in the Protoplanetary Disk of HD 169142 from Multi-Wavelength ALMA Observations
• Radiation pressure clear-out of dusty photoevaporating discs
• Imaging the photoevaporating disk and radio jet of GM Aur
• An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional Disk
• A self-similar solution for thermal disc winds
• A photo-evaporative gap in the closest planet forming disc
• Constraints on photoevaporation models from (lack of) radio emission in the Corona Australis protoplanetary disks
• Probing X-ray photoevaporative winds through their interaction with ionising radiation in cluster environments: the case for X-ray proplyds
• Testing photoevaporation and MHD disk wind models through future high-angular resolution radio observations: the case of TW Hydrae
• Multi-frequency analysis of the ALMA and VLA high resolution continuum observations of the substructured disc around CI Tau. Preference for sub-mm-sized low-porosity amorphous carbon grains