Thermal evolution of of rotating neutron stars

May 6, 2013, 10:15 AM
30m
Habana Libre Hotel

Habana Libre Hotel

Talk STARS2013

Speaker

Rodrigo Negreiros (Universidade Federal Fluminense, Brazil)

Description

Driven by the loss of energy, isolated rotating neutron stars (pulsars) are gradually slowing down to lower frequencies, which increases the tremendous compression of the matter inside of them. This increase in compression changes both the global properties of rotating neutron stars as well as their hadronic core compositions. Both effects may register themselves observationally in the thermal evolution of such stars, as demonstrated in this work. The rotation-driven particle process which we consider here is the direct Urca (DU) process, which is known to become operative in neutron stars if the number of protons in the stellar core exceeds a critical limit of around 11% to 15%. We find that neutron stars spinning down from moderately high rotation rates of a few hundred Hertz may be creating just the right conditions where the DU process becomes operative, leading to an observable effect (enhanced cooling) in the temperature evolution of such neutron stars. As it turns out, the rotation-driven DU process could explain the unusual temperature evolution observed for the neutron star in Cas A, provided the mass of this neutron star lies in the range of 1.5 to 1.9 Mʘ and its rotational frequency at birth was between 40 (400 Hz) and 70% (800 Hz) of the Kepler (mass shedding) frequency, respectively. We will also show the thermal evolution of neutron stars whose spherical symmetry has been broken due to rotation.

Primary author

Rodrigo Negreiros (Universidade Federal Fluminense, Brazil)

Co-authors

Fridolin Weber (San Diego State University, USA) Stefan Schramm (Frankfurt Institute for Advanced Studies, Germany)

Presentation materials