Neutron stars with variable internal heaters

¹ Ioffe Institute - Politechnicheskaya 26, 194021, St. Petersburg, Russia
² Peter the Great St. Petersburg Polytechnic University - Politechnicheskaya 29, 194021, St. Petersburg, Russia
³ Department of Astronomy and Astrophysics, University of Chicago - Chicago, IL 60637, USA

Received: 10 October 2016
Accepted: 21 February 2017

Abstract

We study thermal radiation of a warm neutron star with a variable shell-like heater located in its crust. The heater and the star are taken to be initially in a stationary state. Then the heat power is increased or decreased for some period of time producing a peak or a dip of the thermal surface emission; afterwards the stationary state is restored. Only a small fraction of the generated heat is thermally emitted through the surface. Time variation of the surface luminosity is weakened and distorted with respect to the variation of the generated heat power; the former variation can be observable only under special conditions —neutron stars are “hiding” their internal temperature variations. These results can be useful for the interpretation of the observations of neutron stars with variable thermal surface emission, particularly, magnetars and transiently accreting neutron stars in low-mass X-ray binaries.