2016MNRAS.463..394V -
Mon. Not. R. Astron. Soc., 463, 394-412 (2016/November-3)
Shocks in nova outflows - II. Synchrotron radio emission.
VLASOV A., VURM I. and METZGER B.D.
Abstract (from CDS):
The discovery of GeV gamma-rays from classical novae indicates that shocks and relativistic particle acceleration are energetically key in these events. Further evidence for shocks comes from thermal keV X-ray emission and an early peak in the radio light curve on a time-scale of months with a brightness temperature which is too high to result from freely expanding photoionized gas. B and the efficiency εe of accelerating relativistic electrons of characteristic Lorentz factor γ ∼ 100. If the shocks are radiative (low velocity vsh <= 1000 km s–1) and cover a large solid angle of the nova outflow, as likely characterize those producing gamma-rays, then values of εe ∼ 0.01-0.1 are required to achieve the peak radio brightness for εB = 10–2. Such high efficiencies exclude secondary pairs from pion decay as the source of the radio-emitting particles, instead favouring the direct acceleration of electrons at the shock. If the radio-emitting shocks are instead adiabatic (high velocity), as likely characterize those responsible for the thermal X-rays, then much higher brightness temperatures are possible, allowing the radio-emitting shocks to cover a smaller outflow solid angle.
Abstract Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
acceleration of particles - shock waves - novae, cataclysmic variables - gamma-rays: stars - radio continuum: stars - radio continuum: stars
Simbad objects:
6
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