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COOLING N EUTRON ST A R S: THEORY AND OBSERVATIONS

COOLING N EUTRON ST A R S: THEORY AND OBSERVATIONS. D.G. Yakovlev. Ioffe Physical Technical Institute, St.-Petersburg, Russia. Introduction Neutrino emission Cooling theory Phenomenological concept Theory and observation Connections Conclusions. Main collaborators:

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COOLING N EUTRON ST A R S: THEORY AND OBSERVATIONS

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  1. COOLING NEUTRON STARS: THEORY AND OBSERVATIONS D.G.Yakovlev Ioffe Physical Technical Institute, St.-Petersburg, Russia • Introduction • Neutrino emission • Cooling theory • Phenomenological concept • Theory and observation • Connections • Conclusions • Main collaborators: • A.D. Kaminker, Ioffe Institute • A.Y. Potekhin, Ioffe Institute Hirschegg – January – 2009

  2. Cooling Theory: Primitive and complicated at once

  3. Basic Ideas

  4. PRE-PULSAR HISTORY Stabler (1960) – PhD, First estimates of X-ray surface thermal emission Chiu (1964) – Estimates that neutron stars can be discovered from observations of thermal X-rays Morton (1964) , Chiu & Salpeter (1964), Bahcall & Wolf (1965) – First simplified cooling calculations Tsuruta & Cameron (1966) – Basic formulation of all elements of the cooling theory

  5. 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:

  6. THREECOOLING STAGES

  7. INITIAL THERMAL RELAXATION: LOOK FROM INSIDE AND OUTSIDE

  8. OBSERVATIONS AND BASIC COOLING CURVE Nonsuperfluid star Nucleon core EOS PAL (1988) Modified Urca neutrino emission: slow cooling Talks by Frank Haberl and Slava Zavlin 1=Crab 2=PSR J0205+6449 3=PSR J1119-6127 4=RX J0822-43 5=1E 1207-52 6=PSR J1357-6429 7=RX J0007.0+7303 8=Vela 9=PSR B1706-44 10=PSR J0538+2817 11=PSR B2234+61 12=PSR 0656+14 13=Geminga 14=RX J1856.4-3754 15=PSR 1055-52 16=PSR J2043+2740 17=PSR J0720.4-3125

  9. MODIFIED AND DIRECT URCA PROCESSES 1=Crab 2=PSR J0205+6449 3=PSR J1119-6127 4=RX J0822-43 5=1E 1207-52 6=PSR J1357-6429 7=RX J0007.0+7303 8=Vela 9=PSR B1706-44 10=PSR J0538+2817 11=PSR B2234+61 12=PSR 0656+14 13=Geminga 14=RX J1856.4-3754 15=PSR 1055-52 16=PSR J2043+2740 17=PSR J0720.4-3125

  10. BASIC PHENOMENOLOGICAL CONCEPT Neutrino emissivity function Neutrino luminosity function • Problems: • To discriminate between neutrino mechanisms • To broaden transition from slow to fast neutrino • emission

  11. MODIFIED AND DIRECT URCA PROCESSES: SMOOTH TRANSITION

  12. MODIFIED AND DIRECT URCA PROCESSES: SMOOTH TRANSITION 2p proton SF 9=PSR B1706-44 10=PSR J0538+2817 11=PSR B2234+61 12=PSR 0656+14 13=Geminga 14=RX J1856.4-3754 15=PSR 1055-52 16=PSR J2043+2740 17=PSR J0720.4-3125 1=Crab 2=PSR J0205+6449 3=PSR J1119-6127 4=RX J0822-43 5=1E 1207-52 6=PSR J1357-6429 7=RX J0007.0+7303 8=Vela

  13. MODIFIED AND DIRECT URCA PROCESSES: SMOOTH TRANSITION -- II 2p proton SF Mass ordering is the same!

  14. Neutron stars with strongproton and mild neutron superfluidities in the cores

  15. TESTING THE LEVELS OF SLOW AND FAST NEUTRINO EMISSION Slow neutrino emission: Fast neutrino emission: Two other parameters are totally not constrained

  16. Broadening of threshold for fast neutrino emission Superfluidity: Suppresses ordinary neutrino processes Initiates Cooper-pairing neutrino emission Should be: Strong in outer core to suppress modified Urca Penetrate into inner core to broaden direct Urca threshold Can be: proton or neutron Nuclear physics effects E.,g.pion polarization Voskresensky &Senatorov (1984, 1986) Schaab et al. (1997) Magnetic broadening Baiko & Yakovlev (1999)

  17. Effects of accreted envelopes and surface magnetic fields

  18. Summary of cooling regulators Regulators of neutrino emission in neutron star cores EOS, composition of matter Superfluidity Heat content and conduction in cores Heat capacity Thermal conductivity Thermal conduction in heat blanketing envelopes Thermal conductivity Chemical composition Magnetic field Internal heat sources (for old stars and magnetars) Viscous dissipation of rotational energy Ohmic decay of magnetic fields, ect.

  19. CONNECTION: X-ray transients • Aql X-1 • 4U 1608-522 • RX J1709-2639 • KS 1731-260 • Cen X-4 • SAX J1810.8-2609 • XTE J2123-058 • 1H 1905+000 • SAX 1808.4-3658 Data collected by Kseniya Levenfish Talk by Rudy Wijnands Kaon condensate Pion condensate Direct Urca

  20. CONNECTION: Magnetars Kaminker et al. (2006)

  21. SUMMARY OF CONNECTIONS

  22. CONCLUSIONS Cooling neutron stars Soft X-ray transients Today • Constraints on slow and fast neutrino emission levels • Mass ordering Future • New observations and good practical theories of dense matter • Individual sources and statistical analysis

  23. CONCLUSIONS Ordinary cooling isolates neutron stars of age 1 kyr—1 Myr • There is one basic phenomenological cooling concept • (but many physical realizations) • Main cooling regulator: neutrino luminosity function • Warmest observed stars are low-massive; their neutrino luminosity • seems to be <= 1/30 of modified Urca • Coldest observed stars are more massive; their neutrino luminosity • should be > 30 of modified Urca (any enhanced neutrino emission would do) • Neutron star masses at which neutrino cooling is enhanced are not constrained • The real physical model of neutron star interior is not selected Connections • Directly related to neutron stars in soft X-ray transients (assuming deep crustal • heating). From transient data the neutrino luminosity of massive stars • is enhanced by direct Urca or pion condensation • Related to magnetars and superbusrts Future • New observations and accurate theories of dense matter • Individual sources and statistical analysis

  24. CONCLUSIONS The case is not solved Plenty of work ahead

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

  26. Analytical estimates Thermal balance of cooling star with isothermal interior Slow cooling via Modified Urca process Fast cooling via Direct Urca process

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

  28. 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.

  29. 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

  30. Welcome to the Urca World - II

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