1. Ladek Zdroj, February 2008, Neutrino emission in nonsuperfluid matter The effects of superfluidity 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

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) Threshold: In inner cores of massive stars Similar processes with muons Similar processes with hyperons, e.g. Is forbidden in outer core by momentum conservation:

7. 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 Welcome to the Urca World - I

8. Welcome to the Urca World - II

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

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

11. Enhanced emission in inner cores of massive neutron stars Everywhere in neutron star cores Neutrino Emission Processes in Neutron Star Cores ModelProcess N/H direct Urca Pion condensate Kaon condensate Quark matter Modified Urca Bremsstrahlung

12. Nucleon Matter with Open Direct Urca Process

13. FAST AND SLOW NEUTRINO COOLING SUN

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

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= 1 S 0 B= 3 P 2 (m=0) C= 3 P 2 (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=3x10 8 K 2x10 8 10 8 6x10 7 3x10 7

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 (1)Temperature (2)Composition of the matter (3)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.