catania, october 2012, thermal evolution of neutron stars: theory and observations d.g. yakovlev...
Post on 16-Dec-2015
219 Views
Preview:
TRANSCRIPT
Catania, October 2012,
THERMAL EVOLUTION OF NTHERMAL EVOLUTION OF NEUTRON STEUTRON STAARRS:S:Theory and observationsTheory 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
MAIN NEUTRINO EMISSION MECHANISMS IN NEUTRON STARS
Main features:• unobserved (but governs the cooling)• complete transparency
QdVL
Q
]c [erg luminosity neutrino and
]scm [erg emissivity neutrino :quantity acticalPr1
13
e
ep
n
, e e e en p e p e n n n
27 6 3 19
46 6 19
~ 3 10
~ 10
Q T erg cm s
L T erg s
FeFpFn ppp 02 ~
Direct Urca ProcessLattimer, Pethick, Prakash, Haensel (1991)
Threshold:In inner cores of massive stars
Similar processes with muons
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
SLOW NEUTRINO EMISSION PROCESSES EVERYWHERE IN NEUTRON STAR CORES
, e en N p N e p N e n N
8 6SLOW 0S 9 FAST 0F 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
{
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
Direct Urca
3 10 [erg cm s ]Q
e en p e p e n 26 2710 3 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
Direct Urca
Neutrino emission from cores of non-superfluid NSs
Outer core Inner core Slow emission Fast emission
}
}}
e en p e p e n
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 FAST 0F Q Q T L L T
8 8SLOW 0S SLOW 0S Q Q T L L T
STANDARD
Fast
erg
cm
-3 s
-1
NS with nucleon core: N=n, p
n n
n p
p p
Nucleon Matter with Open Direct Urca Process
FAST AND SLOW NEUTRINO COOLING
FAST AND SLOW NEUTRINO COOLING
SUN
Effects of superfluidity on neutrino emission
Two effects:1.Suppresses traditional neutrino processes2.Creates specific neutrino emission due to Cooper pairing of nucleons
Neutrino emission due to Cooper pairing
Flowers, Ruderman and Sutherland (1976)Voskresensky and Senatorov (1987)Schaab et al. (1997)
n n
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
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)
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
Pradigm SF SF
Minimal cooling off on
Maximal cooling off on
Four cases
Minimal cooling theory:
Page, Lattimer, Prakash, Steiner (2004)
Gusakov, Kaminker, Yakovlev, Gnedin (2004)
Minimal and maximal cooling paradigms
Minimal cooling
Maximal cooling
SF off SF on
~ (10 100)Cooper MurcaL L
Minimal cooling. SF on
Non-superfluid star with nucleon core Standard Murca cooling
Add strong proton super- fluidityVery slow cooling
Add moderate neutron superfluidity: CP neutrino outburst
nn nn
np np
pp pp
nN pNe pNe nN
nN pNe pNe nN
np np
pp pp
nn nn
~ 0.01 MurcaL L MurcaL L
nN pNe pNe nN
nn nn
np np
pp pp
nn
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”)
MAXIMAL COOLINGSTRONG PROTON AND MILD NEUTRON SUPERFLUIDITY
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.
top related