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

TL;DR

This paper revisits the process of induction heating of objects near pulsars, showing that small bodies like asteroids can survive for thousands of years despite intense electromagnetic radiation, challenging previous assumptions about their evaporation.

Contribution

The study provides a detailed calculation of induction heating effects on pulsar companions, revealing size-dependent regimes and survival timescales, and clarifies the conditions under which objects can withstand pulsar environments.

Findings

Asteroids can survive induction heating for about 10^4 years at 1 solar radius from a pulsar.

Induction heating is inefficient for small companions, contrary to previous beliefs.

Degenerate companions are not evaporated by induction heating, implying other heating mechanisms are needed.

Abstract

We investigate the evaporation of close-by pulsar companions, such as planets, asteroids, and white dwarfs, by induction heating. 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. 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. Small objects like asteroids can survive induction heating for $10^4\,$years at distances as small as $1\,R_\odot$ 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.