Electron-beam-induced radio emission from ultracool dwarfs

S. Yu, J. G. Doyle, A. Kuznetsov, G. Hallinan, A. Antonova, A. L. MacKinnon, A. Golden

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

We present the numerical simulations for an electron-beam-driven and loss-cone-driven electron-cyclotron maser (ECM) with different plasma parameters and different magnetic field strengths for a relatively small region and short timescale in an attempt to interpret the recent discovered intense radio emission from ultracool dwarfs. We find that a large amount of electromagnetic (EM) field energy can be effectively released from the beam-driven ECM, which rapidly heats the surrounding plasma. A rapidly developed high-energy tail of electrons in velocity space (resulting from the heating process of the ECM) may produce the radio continuum depending on the initial strength of the external magnetic field and the electron beam current. Both significant linear polarization and circular polarization of EM waves can be obtained from the simulations. The spectral energy distributions of the simulated radio waves show that harmonics may appear from 10 to 70νpepe is the electron plasma frequency) in the non-relativistic case and from 10 to 600νpe in the relativistic case, which makes it difficult to find the fundamental cyclotron frequency in the observed radio frequencies. A wide frequency band should therefore be covered by future radio observations.

Original languageEnglish (US)
Article number60
JournalAstrophysical Journal
Volume752
Issue number1
DOIs
StatePublished - Jun 10 2012

Keywords

  • brown dwarfs
  • magnetic fields
  • masers
  • polarization
  • radio continuum: stars
  • stars: low-mass

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Yu, S., Doyle, J. G., Kuznetsov, A., Hallinan, G., Antonova, A., MacKinnon, A. L., & Golden, A. (2012). Electron-beam-induced radio emission from ultracool dwarfs. Astrophysical Journal, 752(1), [60]. https://doi.org/10.1088/0004-637X/752/1/60