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Testing protoplanetary disc dispersal with radio emission

Testing protoplanetary disc dispersal with radio emission
Testing protoplanetary disc dispersal with radio emission
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 extreme-ultraviolet (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 the 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 an M?2? scaling with free–free flux in the case of EUV-driven disc dispersal or an ?* scaling in the case of X-ray-driven disc dispersal
1365-2966
3378-3388
Owen, J.E.
b0023cf0-9e52-4878-a02f-2c3d4fdc8e9b
Scaife, A M.M.
327b962f-9003-45ca-a6ea-284346c5cc85
Ercolano, B.
98d603e0-3a40-4548-81da-12d7bcb0b0b1
Owen, J.E.
b0023cf0-9e52-4878-a02f-2c3d4fdc8e9b
Scaife, A M.M.
327b962f-9003-45ca-a6ea-284346c5cc85
Ercolano, B.
98d603e0-3a40-4548-81da-12d7bcb0b0b1

Owen, J.E., Scaife, A M.M. and Ercolano, B. (2013) Testing protoplanetary disc dispersal with radio emission. Monthly Notices of the Royal Astronomical Society, 434 (4), 3378-3388. (doi:10.1093/mnras/stt1254).

Record type: Article

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 extreme-ultraviolet (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 the 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 an M?2? scaling with free–free flux in the case of EUV-driven disc dispersal or an ?* scaling in the case of X-ray-driven disc dispersal

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e-pub ahead of print date: 1 August 2013
Published date: 1 October 2013
Organisations: Physics & Astronomy

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Local EPrints ID: 369432
URI: http://eprints.soton.ac.uk/id/eprint/369432
ISSN: 1365-2966
PURE UUID: 23935c05-33e7-461b-97bc-85d6515cc37f

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Date deposited: 26 Sep 2014 10:45
Last modified: 14 Mar 2024 18:04

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Contributors

Author: J.E. Owen
Author: A M.M. Scaife
Author: B. Ercolano

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