Context. The standard cooling models of neutron stars predict temperatures of T < 10 4 K for ages t > 10 7 yr. However, the likely thermal emission detected from the millisecond pulsar J0437-4715, of spin-down age t s ∼ 7×10 9 yr, implies a temperature T ∼ 10 5 K. Thus, a heating mechanism needs to be added to the cooling models in order to obtain agreement between theory and observation. Aims. Several internal heating mechanisms could be operating in neutron stars, such as magnetic field decay, dark matter accretion, crust cracking, superfluid vortex creep, and non-equilibrium reactions ("rotochemical heating"). We study these mechanisms to establish which could be the dominant source of thermal emission from old pulsars. Methods. We show by simple estimates that magnetic field decay, dark matter accretion, and crust cracking are unlikely to have a significant heating effect on old neutron stars. The thermal evolution for the other mechanisms is computed with the code of Fernández and Reisenegger. Given the dependence of the heating mechanisms on the spin-down parameters, we study the thermal evolution for two types of pulsars: young, slowly rotating "classical" pulsars and old, fast rotating millisecond pulsars. Results. We find that magnetic field decay, dark matter accretion, and crust cracking do not produce any detectable heating of old pulsars. Rotochemical heating and vortex creep can be important both for classical pulsars and millisecond pulsars. More restrictive upper limits on the surface temperatures of classical pulsars could rule out vortex creep as the main source of thermal emission. Rotochemical heating in classical pulsars is driven by the chemical imbalance built up during their early spin-down, and is therefore strongly sensitive to their initial rotation period.

IMPORTANCE Although an emergency coronary angiogram (CAG) is recommended for patients who experience an out-of-hospital cardiac arrest (OHCA) with ST-segment elevation on the postresuscitation electrocardiogram (ECG), this strategy is still debated in patients without ST-segment elevation. OBJECTIVE To assess the 180-day survival rate with Cerebral Performance Category (CPC) 1 or 2 of patients who experience an OHCA without ST-segment elevation on ECG and undergo emergency CAG vs delayed CAG. DESIGN, SETTING, AND PARTICIPANTS The Emergency vs Delayed Coronary Angiogram in Survivors of Out-of-Hospital Cardiac Arrest (EMERGE) trial randomly assigned survivors of an OHCA without ST-segment elevation on ECG to either emergency or delayed (48 to 96 hours) CAG in 22 French centers.

The thermal emission detected from the millisecond pulsar J0437-4715 is not explained by standard cooling models of neutron stars without a heating mechanism. We investigated three heating mechanisms controlled by the rotational braking of the pulsar: breaking of the solid crust, superfluid vortex creep, and non-equilibrium reactions ('rotochemical heating'). We find that the crust cracking mechanism does not produce detectable heating. Given the dependence of the heating mechanisms on spin-down parameters, which leads to different temperatures for different pulsars, we study the thermal evolution for two types of pulsars: young, slowly rotating 'classical' pulsars and old, fast rotating millisecond pulsars (MSPs). We find that the rotochemical heating and vortex creep mechanism can be important both for classical pulsars and MSPs.Comment: VIII Symposium in Nuclear Physics and Applications: Nuclear and Particle Astrophysics. Appearing in the American Institute of Physics (AIP) conference proceeding

A proposed measurement of the ß asymmetry in neutron decay with the Los Alamos Ultra-Cold Neutron Source AIP Conf.Abstract. As the rotation of a neutron star slows down, its density increases, pushing the matter inside the star out of beta equilibrium. The beta decays restoring this equilibrium dissipate energy, which heats the star, making it emit thermal ultraviolet radiation for much longer than the standard cooling times. This effect might have been observed in the nearest millisecond pulsar, J0437-4715, by Kargaltsev and collaborators. We show how it operates if the nucleons in the star are superfluid. The steady-state chemical imbalances and temperature increase with the energy gaps, making it possible to constrain the energy gaps from observations. In certain cases, strong oscillations of the temperature can occur. We also analyze competing heating mechanisms, such as vortex friction, and suggest observations that might distinguish between them.

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