Do asteroids evaporate near pulsars? Induction heating by pulsar waves revisited

¹ Sorbonne Universités, UPMC Univ. Paris 6 et CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis bd Arago, 75014 Paris, France
e-mail: kotera@iap.fr
² Department of Astronomy & Astrophysics, Kavli Institute for Cosmological Physics, The University of Chicago, Chicago, IL 60637, USA
³ LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
e-mail: fabrice.mottez@obspm.fr
⁴ Observatoire Astronomique, Université de Strasbourg, 11 rue de l’Université, 67000 Strasbourg, France

Received: 12 January 2016
Accepted: 26 April 2016

Abstract

Aims. We investigate the evaporation of close-by pulsar companions, such as planets, asteroids, and white dwarfs, by induction heating.

Methods. Assuming that the outflow energy is dominated by a Poynting flux (or pulsar wave) at the location of the companions, we calculate their evaporation timescales, by applying the Mie theory.

Results. Depending on the size of the companion compared to the incident electromagnetic wavelength, the heating regime varies and can lead to a total evaporation of the companion. In particular, we find that inductive heating is mostly inefficient for small pulsar companions, although it is generally considered the dominant process.

Conclusions. Small objects like asteroids can survive induction heating for 10⁴ yr at distances as small as 1 R_⊙ from the neutron star. For degenerate companions, induction heating cannot lead to evaporation and another source of heating (likely by kinetic energy of the pulsar wind) has to be considered. It was recently proposed that bodies orbiting pulsars are the cause of fast radio bursts; the present results explain how those bodies can survive in the pulsar’s highly energetic environment.