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COOLING OF YOUNG N EUTRON ST A R S AND THE SUPERNOVA 1987A. D.G. Yakovlev. Ioffe Physical Technical Institute, St.-Petersburg, Russia. Introdu c tion : Is there a problem? Neutron star structure and cooling Thermal relaxation Summary. Ladek Zdroj, February 2008 ,.
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COOLING OF YOUNG NEUTRON STARS AND THE SUPERNOVA 1987A D.G.Yakovlev Ioffe Physical Technical Institute, St.-Petersburg, Russia • Introduction: Is there a problem? • Neutron star structure and cooling • Thermal relaxation • Summary Ladek Zdroj, February 2008,
INTRODUCTION: IS THERE A PROBLEM? Discovery: Shelton, Feb. 23-24, 1987 Las Campanes, Chile Burrows et al. ApJ 543, L149 (2000): High-resolution Chandra observations Park et al. ApJ 610, 275 (2004):
THE BASIC COOLING CURVE Nonsuperfluid star Murca neutrino emission: slow cooling
NEUTRINO EMISSIVITY AND THERMAL CONDUCTIVITY THROUGHOUT A NEUTRON STAR Negel & Vautherin (1973)
EOS npe-matter Prakash, Ainsworth, Lattimer (1988) Page, Applegate (1992)
WILL DIRECT URCA HELP? Nonsuperfluid neutron star models
INITIAL THERMAL RELAXATION: LOOK FROM INSIDE AND OUTSIDE Gnedin et al. (2001)
A LOOK FROM INSIDE: FAST COOLING OF A NONSUPERFLUID STAR
A LOOK FROM INSIDE: SLOW COOLING OF A NONSUPERFLUID STAR
THE RELAXATION TIME tW=? Nomoto, Tsuruta, ApJ 312, 711 (1987) Lattimer, Van Riper, Prakash, Prakash, ApJ 425, 802 (1994) Gnedin, Yakovlev, Potekhin MNRAS 325, 725 (2001)
SCALING OF THE RELAXATION TIME t1 = independent of neutron star model! Lattimer et al. (1994)
RELAXATION TIME OF A NONSUPERFLUID STAR Other physics: Crust-core boundary Thermal conductivity in the core
VERY SHORT RELAXATION Nonsuperfluid strange stars Neutron star with very high thermal conductivity in the inner crust Page, Geppert, Weber (2006)
CONCLUSIONS • Cooling of young neutron stars is almost insensitive to • the physics of their cores; young stars are excellent • natural laboratories of inner crust • A hypothetical neutron star in SN87A should be sufficiently cold • To explain this one should shorten the thermal relaxation time • The relaxation is mainly determined by the physics of the • crust (much less sensitive to the physics of the core) • The natural way to shorten the relaxation time is to assume • strong neutron superfluidity in the inner crust • Other ways to shorten the relaxation are also possible • New observations would be crucial
REFERENCES J.M. Lattimer, K.A. Van Riper, M. Prakash, M. Prakash, Rapid cooling and the structure of neutron stars, Astrophys. J., 425, 802, 1994. O.Y. Gnedin, D.G. Yakovlev, A.Y. Potekhin, Thermal relaxation in young neutron stars. Mon. Not. Roy. Astron. Soc. 324, 725, 2001.