ladek zdroj, february 2008 ,
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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
RICHNESS OF PHYSICAL CONDITIONS
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
NEUTRINO PROCESSES IN NEUTRON STAR CRUST
TEMPERATURE AND DENSITY DEPENDENSE OF NEUTRINO EMISSION
93 10 KT 83 10 KT
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
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
Welcome to the Urca World - II
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
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
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
Nucleon Matter with Open Direct Urca Process
FAST AND SLOW NEUTRINO COOLING
SUN
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
MAIN PHYSICAL MODELS
Problems:To discriminate between neutrino mechanismsTo broaden transition from slow to fast neutrino emission
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)
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”)
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
Distribution over the stellar core
T=3x108 K
2x108
108 6x107
3x107
VQL d CPCP
Neutrino luminosity due to Cooper pairing
8)10010(~ TLL MurcaCooper
Gusakov et al. (2004)
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
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.