Download - Ladek Zdroj, February 2008 ,
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Ladek Zdroj, February 2008,
• Neutrino emission in nonsuperfluid matter• The effects of superfluidity
COOLING OF NCOOLING OF NEUTRON STEUTRON STAARRSS 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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RICHNESS OF PHYSICAL CONDITIONS
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MAIN NEUTRINO EMISSION MECHANISMS IN NEUTRON STARS
Main features:• unobserved (but governs the cooling)• complete transparency• neutrino energies ~ kT• massless but low-energy neutrinos
QdVL
Q
]c [erg luminosity neutrino and
]scm [erg emissivity neutrino :quantity acticalPr1
13
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NEUTRINO PROCESSES IN NEUTRON STAR CRUST
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TEMPERATURE AND DENSITY DEPENDENSE OF NEUTRINO EMISSION
93 10 KT 83 10 KT
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e
ep
n
, e e e en p e p e n n n
dfffwQ epnfi )1)(1(2
npeepn
A Tcmmm
gGQ
6310
22 )31(10080457
27 6 3 19
46 6 19
~ 3 10
~ 10
Q T erg cm s
L T erg s
FeFpFn ppp 02 ~
n
Direct Urca ProcessLattimer, 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:
0 9 330 MeV/c, 120 MeV/c, ~ / ~ 0.1 MeV/cFn Fe Fp Bp p p p k T c T
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Gamow and Shoenberg: Casino da Urca in Rio de Janeiro
Neutrino theory of stellar collapse, Phys. Rev. 59, 539, 1941:
Unrecordable cooling agent
Photo andStory by R. Ruffini
Welcome to the Urca World - I
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Welcome to the Urca World - II
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ENCHANCED NEUTRINO EMISSION PROCESSES IN CORES OF MASSIVE NEUTRON STARS
, e e e en p e p e n n n
, n p p n
, e en e n e
0, =( , ), =( , , )e eB B e B e B B n B p
, =( , ) e eN N e N e N N n p
, e ed u e u e d
Prakash, Prakash, Lattimer, Pethick (1992)
Maxwell et al. (1977)
Brown et al. (1992)
Iwamoto (1980, 1982)
6 6FAST 0F 9 FAST 0F 9 Q Q T L L T
NUCLEON-HYPERON MATTER
PION CONDENSATE
KAON CONDENSATE
QUARK MATTER
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SLOW NEUTRINO EMISSION PROCESSES EVERYWHERE IN NEUTRON STAR CORES
, e en N p N e p N e n N
8 8SLOW 0S 9 FAST 0S 9 Q Q T L L T
MODIFIED URCA [N=n or p = nucleon-spectator]
NUCLEON-NUCLEON BREMSSTRAHLUNG
N N N N
n n n n
n p n p
p p p p
{
LEPTON MODIFIED URCA, BREMS IN COULOMB COLLISIONS
, [ =any charged fermion]e eC e C e C C C
e C e C
Bahcall and Wolf (1965), Friman and Maxwell (1979), Maxwell (1987),Yakovlev and Levenfish (1995)
Friman and Maxwell (1979)
Any neutrino flavor
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Enhanced emission in inner cores of massive neutron stars
Everywhere in neutron star cores
Neutrino Emission Processes in Neutron Star Cores
6 6FAST 0F 9 FAST 0F 9 Q Q T L L T
Model Process
N/H direct Urca
Pion condensate
Kaon condensate
Quark matter
3 10 [erg cm s ]Q
e eN N e N e N
e eB B e B e B
e ed u e u e d
e eB B e B e B 26 2710 3 10 23 2610 1023 2410 1023 2410 10
8 8SLOW 0S 9 FAST 0S 9 Q Q T L L T
Modified Urca
Bremsstrahlung
nN pNe pNe nN
N N N N
20 2110 3 10
19 2010 10
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Nucleon Matter with Open Direct Urca Process
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FAST AND SLOW NEUTRINO COOLING
SUN
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Direct Urca, N/H
Neutrino Emission Processes in Neutron Star CoresOuter core Inner coreSlow emission Fast emission
}
}
}}
}
e en p e p e n
Pion condensate
Kaon condensation
Or quark matter
e eN N e N e N
e eB B e B e B
e ed u e u e d
Modified Urca nN pNe pNe nN
NN bremsstrahlung N N N N
Enhanced emission in inner cores of massive neutron stars:
Everywhere in neutron star cores:
6 6FAST 0F 9 FAST 0F 9 Q Q T L L T
8 8SLOW 0S 9 FAST 0S 9 Q Q T L L T
STANDARD
Fast erg
cm
-3 s
-1
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MAIN PHYSICAL MODELS
Problems:To discriminate between neutrino mechanismsTo broaden transition from slow to fast neutrino emission
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SUPERFLUID SUPPRESSION OF NEUTRINO EMISSION
0( , ) ( , ) = neutrino emissivity depends on / = superfluid reduction factorc
Q T Q T RR T T
is exponentially suppressed by strong superfluidity (at )c
R
T T
A=1S0
B=3P2 (m=0)C=3P2 (m=2)
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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”)
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Cooper pairing neutrino emission
Flowers, Ruderman and Sutherland (1976) NN ~~
s cmerg )/( 1017.1 3
79
F*
21cN
NN
N TTFaNTcm
pmmQ
Only the standard physics involved
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Distribution over the stellar core
T=3x108 K
2x108
108 6x107
3x107
VQL d CPCP
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Neutrino luminosity due to Cooper pairing
8)10010(~ TLL MurcaCooper
Gusakov et al. (2004)
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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
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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.