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Ladek Zdroj, February 2008 ,

COOLING OF N EUTRON ST A R S. D.G. Yakovlev. Ioffe Physical Technical Institute, St.-Petersburg, Russia. 1. Formulation of the Cooling Problem 2. Superlfuidity and Heat Capacity 3. Neutrino Emission 4. Cooling Theory versus Observations.

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Ladek Zdroj, February 2008 ,

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  1. COOLING OF NEUTRON STARS D.G.Yakovlev Ioffe Physical Technical Institute, St.-Petersburg, Russia 1. Formulation of the Cooling Problem 2. Superlfuidity and Heat Capacity 3. Neutrino Emission 4. Cooling Theory versus Observations • Neutrino emission in nonsuperfluid matter • The effects of superfluidity Ladek Zdroj, February 2008,

  2. RICHNESS OF PHYSICAL CONDITIONS

  3. MAIN NEUTRINO EMISSION MECHANISMS IN NEUTRON STARS • Main features: • unobserved (but governs the cooling) • complete transparency • neutrino energies ~ kT • massless but low-energy neutrinos

  4. NEUTRINO PROCESSES IN NEUTRON STAR CRUST

  5. TEMPERATURE AND DENSITY DEPENDENSE OF NEUTRINO EMISSION

  6. Direct Urca Process Lattimer, Pethick, Prakash, Haensel (1991) Is forbidden in outer core by momentum conservation: In inner cores of massive stars Threshold: ~ Similar processes with muons Similar processes with hyperons, e.g.

  7. Welcome to the Urca World - I Gamow and Shoenberg: Casino da Urca in Rio de Janeiro Neutrino theory of stellar collapse, Phys. Rev. 59, 539, 1941: Unrecordable cooling agent Photo and Story by R. Ruffini

  8. Welcome to the Urca World - II

  9. ENCHANCED NEUTRINO EMISSION PROCESSES IN CORES OF MASSIVE NEUTRON STARS NUCLEON-HYPERON MATTER Prakash, Prakash, Lattimer, Pethick (1992) PION CONDENSATE Maxwell et al. (1977) KAON CONDENSATE Brown et al. (1992) QUARK MATTER Iwamoto (1980, 1982)

  10. SLOW NEUTRINO EMISSION PROCESSES EVERYWHERE IN NEUTRON STAR CORES MODIFIED URCA [N=n or p = nucleon-spectator] Bahcall and Wolf (1965), Friman and Maxwell (1979), Maxwell (1987), Yakovlev and Levenfish (1995) NUCLEON-NUCLEON BREMSSTRAHLUNG { Any neutrino flavor Friman and Maxwell (1979) LEPTON MODIFIED URCA, BREMS IN COULOMB COLLISIONS

  11. Neutrino Emission Processes in Neutron Star Cores Enhanced emission in inner cores of massive neutron stars Everywhere in neutron star cores

  12. Nucleon Matter with Open Direct Urca Process

  13. FAST AND SLOW NEUTRINO COOLING SUN

  14. Neutrino Emission Processes in Neutron Star Cores Outer coreInner core Slow emission Fast emission Direct Urca, N/H Pion condensate erg cm-3 s-1 } } Kaon condensation Or quark matter Fast } } STANDARD Modified Urca } NN bremsstrahlung Enhanced emission in inner cores of massive neutron stars: Everywhere in neutron star cores:

  15. MAIN PHYSICAL MODELS Problems: To discriminate between neutrino mechanisms To broaden transition from slow to fast neutrino emission

  16. SUPERFLUID SUPPRESSION OF NEUTRINO EMISSION A=1S0 B=3P2 (m=0) C=3P2 (m=2)

  17. AN EXAMPLE OF SUPERFLUID REDUCTION OF NEUTRINO EMISSION Two models for proton superfluidity Neutrino emissivity profiles • Superfluidity: • Suppresses modified Urca process in the outer core • Suppresses direct Urca just after its threshold (“broadens • the threshold”)

  18. Cooper pairing neutrino emission Flowers, Ruderman and Sutherland (1976) Only the standard physics involved

  19. Distribution over the stellar core T=3x108 K 2x108 108 6x107 3x107

  20. Neutrino luminosity due to Cooper pairing Gusakov et al. (2004)

  21. Summary of neutrino emission properties • Neutrino emission from neutron star cores is strongly regulated by • Temperature • Composition of the matter • Superfluidity • These regulators may affect the emissivity in a non-trivial way • (enhance or suppress) • What is their effect?  Next lecture

  22. REFERENCES U. Lombardo, H.-J. Schulze. Superfluidity in neutron star matter. In: Physics of Neutron Star Interiors, edited by D. Blaschke, N. Glendenning, A. Sedrakian, Berlin: Springer, 2001, p. 30. D.G. Yakovlev, K.P. Levenfish, Yu.A. Shibanov. Cooling of neutron stars and superfluidity in their cores. Physics – Uspekhi 42, 737, 1999. D.G. Yakovlev, A.D. Kaminker, O.Y. Gnedin, P. Haensel. Neutrino emission from neutron stars. Phys. Rep. 354, Nums. 1,2, 2001.

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