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Catania, October 2012, THERMAL EVOLUTION OF NEUTRON STARS: Theory and observations D.G. Yakovlev Ioffe Physical Technical Institute, St.-Petersburg, Russia.

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Presentation on theme: "Catania, October 2012, THERMAL EVOLUTION OF NEUTRON STARS: Theory and observations D.G. Yakovlev Ioffe Physical Technical Institute, St.-Petersburg, Russia."— Presentation transcript:

1 Catania, October 2012, THERMAL EVOLUTION OF NEUTRON STARS: Theory and observations 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 MAIN NEUTRINO EMISSION MECHANISMS IN NEUTRON STARS Main features: unobserved (but governs the cooling) complete transparency

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

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

5 Enhanced emission in inner cores of massive neutron stars Everywhere in neutron star cores Neutrino Emission Processes in Neutron Star Cores ModelProcess Direct Urca Modified Urca Bremsstrahlung

6 Direct Urca Neutrino emission from cores of non-superfluid NSs Outer core Inner core Slow emission Fast emission } } } 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 NS with nucleon core: N=n, p

7 Nucleon Matter with Open Direct Urca Process

8 FAST AND SLOW NEUTRINO COOLING

9 SUN

10 Effects of superfluidity on neutrino emission Two effects: 1.Suppresses traditional neutrino processes 2.Creates specific neutrino emission due to Cooper pairing of nucleons

11 Neutrino emission due to Cooper pairing Flowers, Ruderman and Sutherland (1976) Voskresensky and Senatorov (1987) Schaab et al. (1997) Temperature dependence of neutrino emissivity due to Cooper pairing Features: Efficient only for triplet-state pairing of neutrons Non-monotonic T-dependence Strong many-body effects Leinson (2001 ) Leinson and Perez (2006) Sedrakian, Muether, Schuck (2007) Kolomeitsev, Voskresensky (2008) Steiner, Reddy (2009) Leinson (2010) Physics: Jumping over cliff from branch A to B A B Neutrino emission due to Cooper pairing

12 Distribution over the stellar core T=3x10 8 K 2x x10 7 3x10 7

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

14 Minimal and maximal cooling paradigms Consider neutron stars with nucleon cores (simplest composition) Minimal cooling paradigm: no direct Urca in all stars Maximal cooling paradigm: direct Urca in heavy stars PradigmSF Minimal coolingoffon Maximal coolingoffon Four cases Minimal cooling theory: Page, Lattimer, Prakash, Steiner (2004) Gusakov, Kaminker, Yakovlev, Gnedin (2004)

15 Minimal and maximal cooling paradigms Minimal cooling Maximal cooling SF offSF on

16 Minimal cooling. SF on Non-superfluid star with nucleon core Standard Murca cooling Add strong proton super- fluidity Very slow cooling Add moderate neutron superfluidity: CP neutrino outburst

17 MAXIMAL COOLING 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 MAXIMAL COOLING STRONG PROTON AND MILD NEUTRON SUPERFLUIDITY

19 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

20 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, 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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