nuclear incompressibility and compact stars fridolin weber, san diego state university
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Nuclear Incompressibility and Nuclear Incompressibility and Compact StarsCompact Stars
Fridolin Weber, San Diego State University
Influence of Influence of Incompressibility & Symmetry Incompressibility & Symmetry
Energy on NS PropertiesEnergy on NS Properties Core composition (hyperons, bosons, quarks;
superfluid protons, superconducting quarks)
Neutron star masses (1.25 Msun
, 1.7 Msun
)
Fast rotation (Kepler, GW instabilities)
Do sub-millisecond pulsars exist?
Superconducting quark matter (CFL, 2SC, LOFF, ...)
r-modes
Cooling (mean free path, heat capacity, conductivity, neutrino emissivity)
Pulsar kicks
Magnetic fields
Gamma ray bursts
Signals of phase transitions
Evolutionary transitions (neutron star to strange star transition)
Surface gravity (mass accretion, frame dragging, red-shifted/blue-shifted photons)
Nuclear crust thickness (isolated neutron stars, LMXBs, pulsar glitches)
Gravity waves from neutron stars (e.g., r-modes, f-modes, ...)
Stellar cooling
Proto-neutron stars
X-ray burster
. . . .
Selected Neutron Star MassesSelected Neutron Star Masses
J1713+0747: 1.3 Msun
B1855+09: 1.6±0.2 Msun
J0621+1002: 1.7±0.6 Msun
+0.4-0.5
Vela X-1: 2.27± 0.17; 1.88±0.13
J1829+2456: companion mass 1.22 to 1.38 Msun
Vela X-1: 1.88±0.13 Msun
, 2.27±0.17 Msun
+0.3
J0751+1807: 2.1 Msun
+0.9
Cyg X-2: 1.44±0.06 Msun
, R=9.0±0.5 km @ 11 kpc
0.97±0.04 Msun
, R=7.7±0.4 km @ 9 kpc
J0737-3039: 1.249±0.001 Msun
D. Nice et al. (2004)
95% cfl
68% cfl
Mass-Radius Relationship of Mass-Radius Relationship of Neutron and Quark StarsNeutron and Quark Stars
“Neutron” stars R > 10 km
Quark starsR < 10 km~ ~
Metric: ds2 = − e−2ν dt2 + e2(α+β ) r2 sin2ϑ (dφ – Nφ dt)2 + e2(α–β) (dr2 + r2 dϑ2)
Christoffel symbols: Гσ
μν= gσλ (∂
νg
μλ + ∂
μg
νλ – ∂
λg
μν) / 2
Riemann tensor: Rτ
μνσ = ∂
νГτ
μσ – ∂
σГτ
μν + Гκ
μσГτ
κν – Γκ
μνΓτ
κσ
Ricci tensor: Rμν
= Rτμσν
gστ
Scalar curvature: R = Rμν
gμν
Kepler frequency: ΩK = r–1 eν–α–β U
K + Nφ at r=R
eq
Einstein's Field Equations for Rotating Compact ObjectsEinstein's Field Equations for Rotating Compact Objects
I=> Stellar properties: M, R
p, R
eq, I, z, Ω
K, ω
=> Stellar properties: M, R
p, R
eq, I, z, Ω
K, ω
Dependence of Particle Thresholds on SpinDependence of Particle Thresholds on SpinFrequency of a Neutron StarFrequency of a Neutron Star
F. Weber, Prog. Nucl. Part.Phys. 54 (2005) 193-288
60% change!!
Rotation at Mass Shedding FrequencyRotation at Mass Shedding Frequency
PK = 2π/Ω
K
= 2π√(R3/M)
Parkes radio telescope
strange quarkstars
strange quarkstars
“neutron”stars
“neutron”stars
CFL
1.6 ms
Quark-Hadron CompositionQuark-Hadron Composition(Relativistic Hartree)(Relativistic Hartree)
Hyperons Nucleons only
Stellar Composition (M~1.4 MStellar Composition (M~1.4 Msunsun))
p,nliquid
p,nliquid
“Traditional” NS Quark-hybrid star Quark-hybrid star
Quark-Hadron Composition in RotatingQuark-Hadron Composition in Rotating““Neutron” StarsNeutron” Stars
Equatorial direction Polar direction
30
10 0
(~5 km)
(~3 km)
Glendenning, Pei, Weber,PRL 79 (1997) 1603
ν=220 Hz
ν=65 Hz
Weber, J. Phys. G: Nucl. Part. Phys. 25 (1999) R195
Weber, Prog. Part. Nucl.Phys. 54 (2005) 193
Open issue: stability?
5.5 km
1.9 km
14.3 km
Differentially Rotating Stellar Objects
Ω
M=1.4 Msun
νeq
=290 Hzν
c=140 ν
eq
Pulsar B (1.25 MPulsar B (1.25 Msunsun) in J0737-3039) in J0737-3039
P. Podsiadlowski et al., MNRAS (in press)
K=240 MeV
m*/m=0.78
asym
=32 MeV
My analysis: variational calculation (WUU),My analysis: variational calculation (WUU), RMF, and RBHF (Brockmann B)RMF, and RBHF (Brockmann B) lead to Mlead to M
byby = 1.365 to 1.375 M = 1.365 to 1.375 Msunsun
provided provided
at nuclear matter saturation density.at nuclear matter saturation density.
Spin Frequency Evolution of Spin Frequency Evolution of Neutron Stars in LMXB'sNeutron Stars in LMXB's
Frequency Distribution of X-Ray Frequency Distribution of X-Ray Neutron StarsNeutron Stars
Glendenning & Weber, ApJ 559 (2001) L119
Histogram of Neutron Stars Spin Histogram of Neutron Stars Spin FrequenciesFrequencies(from L. Bildsten, astro-ph/0212004)
Solid lineis forMSPs in47 Tuc
Dashed line is for4U 1916-0534U 1702-4294U 1728-34KS 1731-260Aql X-1MXB 1658-2984U 1636-53MXB 1743-29SAX J1750.8-29804U 1608-52Sax J1808.4-3658XTE J1751-305XTE J0929-314
Populationdecline to high frequen-cies in 47 Tuc
Relativistic Nuclear Field-TheoryRelativistic Nuclear Field-TheoryL = Ψ
B(iγμ∂
μ – m
B) Ψ
B + Mesons (σ,ω,π,ρ,η,δ,ϕ) + Interactions
Baryons: (iγμ∂μ – m
B) Ψ
B = g
σB σ ψ
B +
g
ωB γμω
μψ
B + ...
Mesons: (∂μ∂μ + m
σ2) σ = Σ
B g
σB ψ
B ψ
B
T=V + ∫ V [g g] T
∑=∫ T g
g = g0 + g0 ∑ g
=> P(ρ)
T=V + ∫ V [g g] T
∑=∫ T g
g = g0 + g0 ∑ g
=> P(ρ)
σ, ω, π, ρ, ...
B1
B'1 B'
2
B2
Γ1
Γ2
T matrix
RXJ 1856.5-3754RXJ 1856.5-3754
Discovered serendipitously in study of pre-main-sequence stars in R CrA star forming region • Brightest INS candidate in X-rays HST parallax => 110-175 pc
(Walter & Lattimer 2002; Kaplan et al 2002; 175 pc - Kaplan 2003!)• Proper motion points to Upper Scorpius OB association => age~106yr
Braking of PulsarsBraking of Pulsars
n = (Ω d2Ω/dt2)/(dΩ/dt)2
= 3 – (I'' Ω2+3I' Ω)/(I' Ω+2I)
n = (Ω d2Ω/dt2)/(dΩ/dt)2
= 3 – (I'' Ω2+3I' Ω)/(I' Ω+2I)
Isolated pulsars spin down becauseof energy and angular momentumloss due to radiative processes
Crab/VLT/ESO
(I'≡dI/dΩ)
ddE/dt = d/dt (½ I Ω2) = - C Ωn+1
Braking index:
Ω
Possible Astrophysical Signal of Possible Astrophysical Signal of Quark DeconfinementQuark Deconfinement
Epoch over which “n” is anomalousEpoch over which “n” is anomalous
~108 years
About 10% of the existingmillisecondpulsar population could signalquark deconfinementin their centers!
Neutron Star TemperaturesNeutron Star Temperatures
Dany Page, Seoul, South Korea, 2003 (http://beauty.phys.pusan.ac.kr/~astro/)
Rotating Neutron Star (Pulsar)
Facts about pulsars:
M~1-2 Msun
R~10 km
P>1.58 ms (630 Hz) B~1012 G # ~108-1010 (1% M
Galaxy)
Facts about pulsars:
M~1-2 Msun
R~10 km
P>1.58 ms (630 Hz) B~1012 G # ~108-1010 (1% M
Galaxy)
ρ~1015 g/cm3
B
Ω
Nuclear Nuclear IncompressibilityIncompressibility
and and Compact StarsCompact Stars
Fridolin WeberDepartment of Physics
San Diego State University
JINA Workshop on Nuclear Incompressibility and the Nuclear Equation of State, July 14-15, 2005