Neutron star cooling in transiently accreting low mass binaries : a new tool for probing nuclear matter
نویسندگان
چکیده
We explore, using an exact cooling code, the thermal evolution of a neutron star undergoing episodes of intense accretion, alternated by long periods of quiescence (e.g. Soft X-Ray Transients; SXRTs hereon). We find that the soft component of the quiescent luminosity of Aql X-1, 4U 1608-522 and of SAX J1808.4-3658 can be understood as thermal emission from a cooling neutron star with negligible neutrino emission. In the case of Cen X-4 strong neutrino emission from the inner core is necessary to explain the observation: this may indicate that the neutron star of Cen X-4 is heavier than 1.4 M⊙ . This study opens the possibility of using the quiescent emission of SXRTs as a tool for probing the core superfluidity in relation to the mass of the neutron star.
منابع مشابه
Thermal State of Transiently Accreting Neutron Stars
We study thermal states of transiently accreting neutron stars (with mean accretion rates Ṁ ∼ 10 − 10 M⊙ yr ) determined by the deep crustal heating of accreted matter sinking into stellar interiors. We formalize a direct correspondence of this problem to the problem of cooling neutron stars. Using a simple toy model we analyze the most important factors which affect the thermal states of accre...
متن کاملForty Years of X-Ray Binaries
In 2012 it was forty years ago that the discovery of the first X-ray binary Centaurus X-3 became known. That same year it was discovered that apart from the High-Mass X-ray Binaries (HMXBs) there are also Low-Mass X-ray Binaries (LMXBs), and that Cygnus X-1 is most probably a black hole. By 1975 also the new class of Be/X-ray binaries was discovered. After this it took 28 years before ESAs INTE...
متن کاملConditions for Steady Gravitational Radiation from Accreting Neutron Stars
The gravitational-wave and accretion driven evolution of the angular velocity, core temperature, and (small) amplitude of an r-mode of neutron stars in low mass X-ray binaries and similar systems is investigated. The conditions required for evolution to a stable equilibrium state (with gravitational wave flux proportional to average X-ray flux) are determined. In keeping with conclusions derive...
متن کاملGravitational Waves and the Maximum Spin Rate of Accreting Neutron Stars
Accreting neutron stars in the weakly magnetic Low-Mass XRay Binaries (LMXBs) are expected to be spun up near the breakup frequency ∼> 1 kHz in a small fraction of their age. The lack of observed systems above ∼ 600−700Hz has led to the suggestion that gravitational-wave spindown torque may be setting a maximum rotation rate. If true, searches for sub-millisecond radio pulsars will not be succe...
متن کاملMillisecond Oscillations in X-ray Binaries
The first millisecond X-ray variability phenomena from accreting compact objects have recently been discovered with the Rossi X-ray Timing Explorer. Three new phenomena are observed from low-mass X-ray binaries containing low-magneticfield neutron stars: millisecond pulsations, burst oscillations and kiloHertz quasiperiodic oscillations. Models for these new phenomena involve the neutron star s...
متن کامل