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Physics of Compact Stars

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Physics of Compact Stars Physics of Compact Stars • Crab nebula: Supernova 1054 • Pulsars: rotating neutron stars • Death of a massive star • Pulsars: lab’s of many-particle physics • Equation of state and star structure • Phase diagram of nuclear matter • Rotation and accretion • Cooling of neutron stars • Neutrinos and gamma-ray bursts • Outlook: particle astrophysics David Blaschke - IFT, University of Wroclaw - Winter Semester 2007/08 1 Example: Crab nebula and Supernova 1054 1054 Chinese Astronomers observe ’Guest-Star’ in the vicinity of constellation Taurus – 6times brighter than Venus, red-white light – 1 Month visible during the day, 1 Jahr at evenings – Luminosity ≈ 400 Million Suns – Distance d ∼ 7.000 Lightyears (ly) (when d ≤ 50 ly Life on earth would be extingished) 1731 BEVIS: Telescope observation of the SN remnants 1758 MESSIER: Catalogue of nebulae and star clusters 1844 ROSSE: Name ’Crab nebula’ because of tentacle structure 1939 DUNCAN: extrapolates back the nebula expansion −! Explosion of a point source 766 years ago 1942 BAADE: Star in the nebula center could be related to its origin 1948 Crab nebula one of the brightest radio sources in the sky CHANDRA (BLAU) + HUBBLE (ROT) 1968 BAADE’s star identified as pulsar 2 Pulsars: Rotating Neutron stars 1967 Jocelyne BELL discovers (Nobel prize 1974 for HEWISH) pulsating radio frequency source (pulse in- terval: 1.34 sec; pulse duration: 0.01 sec) Today more than 1700 of such sources are known in the milky way ) PULSARS Pulse frequency extremely stable: ∆T=T ≈ 1 sec/1 million years 1968 Explanation of the phenomenon GOLD as ) RO- TATING NEUTRON STARS, since: – only Rotation explains high precision of pulses – only small objects (R ≈ 10 km) can have so small pulse duations 1969 Discovery of the pulsar in the Crab nebula Connection established: SUPERNOVA - NEUTRON STAR - PULSAR 1968 Discovery of the binary Pulsar PSR 1913+16 by HULSE and TAYLOR (Nobel prize 1993) 3 What happens in a Supernova-Explosion ? Two Szenarios after ceasing of nuclear fusion reactions in the star interior • Supernova Type I (Carbon core): Explosive ’Burning’, star is completely destroyed • Supernova Type II (Iron core): Implosion due to gravitational instability, subsequent shockwave explosion and neutrino emission ) blast of the star envelope, star interior collapses ) NEUTRON STAR or BACK HOLE Neutron star-Properties: • Radius: R ≈ 10 km • Density: ρ ≈ 1014 : : : 1015 g/cm3 30 • Mass: M ≈ M = 2 × 10 kg • Rotation: Period T < 1 sec, for progenitor star T ≈ 30 d (Sun) • Magnetic field: contraction increases the density of field lines dramatically 12 ! H=Hearth ≈ 10 4 Pulsars: Laboratories for Many-particle Physics Glitches: Superfluid Nuclear Matter 1970 1975 1980 11.21 11.208 11.206 Frequenzy f (Hz) 11.204 11.202 0 2000 4000 6000 Julian Date −2440000.5 Nature of Glitches: Vortex-Crust Unpinning ! suddenly smaller momet of inertia ! jump in Ω = dφ/dt (angular momentum conserva- tion) Lecture: Astronomie II online, Notebook University Rostock (NUR) http://www.mpg.uni-rostock.de/tap/astro/ 5 Phase diagram for QCD Matter at high densities Big Bang Quark-Gluon-Plasma 1.5 RHIC, LHC (construction) Challenge to Experiments DECONFINEMENT CERN-SPS FAIR (Project) and Questions to AGS Brookhaven Theory: H Hadron gas [T =140 MeV] [T =140 • How do Quarks get their SIS Darmstadt masses (χSB)? Quark Matter • Why are there no free Quarks QCD - Lattice Gauge Theory Super- Temperature Novae Heavy Ion Collisions and Gluons (Confinement)? CONFINEMENT COLOR SUPERCONDUCTIVITY 0.1 Nuclear matter Neutron / Quark Stars -3 1 Baryon Density 3 [n ο =0.16 fm ] Virtual Institute (2003-06): “Dense hadronic matter and QCD phase transitions” (UNIs Bielefeld, Darmstadt, Frankfurt, Giessen, Rostock, Tubingen¨ mit GSI Darmstadt) 6 Equation of State and Stability of Compact Stars Tolman-Oppenheimer-Volkoff Equations 1. Stability: General Relativistic Hydrostatic Equilibrium − dP (r) m(r)"(r) P (r) 4πr3P (r) 2Gm(r) 1 = −G 1 + 1 + 1 − dr r2 "(r) m(r) r NEWTON EINSTEIN CORRECTIONS GENERAL REL. THEORY R 2 2. Mass Distribution: m(R) = 0 "(r) 4π r dr R 2.5 0.7 0.6 0.5 RX J1856 0.4 EXO 0748-676 2.0 causality 4Uconstraint 1636-536 0.3 ] -3 2 10 ] 0.2 sun 1.5 4U 0614 +09 Flow constraint XTE J1739-285 DBHF (Bonn A) M [M 1.0 η η DBHF D = 0.92, V = 0.0 z = 0.1 P [MeV fm η = 0.92, η = 0.0 η η D V D = 1.00, V = 0.5 η η η = 1.02, η = 0.5 D = 1.00, V = 0.5 D V 1 0.5 η η η = 1.03, η = 0.5 D = 1.03, V = 0.5 10 D V η η η η D = 1.00, V = 0.0 D = 1.02, V = 0.5 0 0.2 0.4 0.6 0.8 1 8 10 12 14 -3 n [fm ] R [km] 7 N =1.55 N N =1.8 N NB=1.3 NO B O B O 15 R R e R Rotation and Star Structure e e 12 R R p R p H p Axially symmetric solutions of the EINSTEIN- 9 equations for compact stars show:: H r [km] H M • Deformation (Excentricity) 6 M • new density distribution (centrifugal forces) 3 Q Q • further general relativity effects M 0 0 2 4 6 0 2 4 6 0 2 4 6 Ω [kHz] Ω [kHz] Ω [kHz] Ω No Stationary Rotating Stars Phase transition to Quark matter depends on 150 88 Mass (Baryon number N) and Angular veloc- Ω 144 ity (Ω = dφ/dt) of the Star! 132 126 66 114 108 102 120 96 90 84 78 72 66 Phase diagram (Ω − N plane) =) 60 visualizes observable Signals: 44 • Braking index (spin-down) 22 • Population-clustering (accretion) Hadronic Stars Quark Core Stars Black Holes Moment of inertia () Phase transition! 0 2 4 6 [kHz] 22 11 1.51.5 N 2.252.25 1.751.75 1.251.251.25 1.5 1.75 2.0 N/N . 8 Low-mass X-ray Binary (LMXB) LMXB’s show: • Accretion (N - Evolution) • X-ray bursts with quasiperiodic Brightness Oscillations (QPO’s) • further general rel. effects (ISCO) 10 1.6 over 100 million years 9 about 60 million years 1.4 8 No Stationary Rotating Stars Phase transition Signal: 1.2 7 N (Ω) ) Population clustering at Ncrit(Ω) crit Ω Ω (N) ( 1.0 6 max max N 5 0.8 {kHz] Hadronic Stars [kHz] QPO-Phenomenon gives informations about: ν Ω 4 0.6 • Mass-radius relation 3 0.6 TG 0.4 Black Holes • 2 1.0 TG Rotation frequency 0.2 1 Quark Core Stars Ω−N plane () Hertzsprung-Russell- 0 0 1.2 1.4 1.6 1.8 2 2.2 Diagram for QPO’s! N [Nsun] 9 Cooling of Compact Stars-Results Cooling of Hybrid stars with 2SC Quark core T =40 MeV T = 0 HJ (Y - 3P *0.1) with K = 240 MeV with Med. effects, our crust, Gaussian FF 2 ν γ e ν e γ γ 1.10 γ 1.214 critical γ γ 1.217 QM γ γ 6.4 ν ν 2SC 1.25 e e ν e Crab 1.32 1.42 γ RX J0822-43 ν γ 1.5 γ e 1.65 1.75 γ 6.2 1E 1207-52 1.793 ν e γ γ RX J0002+62 [K]) s PSR J0205+64 in 3C58 6 PSR 0656+14 log(T PSR 1055-52 Vela Neutrinos carry energy off the star Geminga 5.8 CTA 1 =) Cooling evolution given by j dT (t) γ + j=URCA;::: ν RX J1865-3754 = − 5.6 P i dt i=q,e,γ;::: cV 1 2 3 4 5 6 7 P log(t[yr]) - • Enhanced Cooling by URCA ) Signal ν • 2SC+X phase, ∆X ∼ 30 keV e- • Pulsar in 3C58 - candidate for a Quark Star? Grigorian, DB, Voskresensky: Phys. Rev. C 71 d u (2005) 10 Magnetic Quark Star: Neutrino Beam { Gamma-Ray-Burst • Neutrinos trapped in a star when temperature T > 1 MeV (≈ 1010K) ! mean free path R vortex star surface • 2SC quark matter core with magnetic vortices (B∼ 1016 G) superconductor • Beamed emission neutrinos, ∆E ∼ 1052 erg R ν,ν G λ G ν G e + ν • Conversion of neutrinos ! photons: Gamma-Ray Burst (?) γ θ ν ν,ν γ ν e 1e+53 13 B = 10 G conversion 14 1e+52 B = 10 G 15 B = 10 G 1e+51 16 B = 10 G 17 L [erg/s] 1e+50 B = 10 G 30 20 T [MeV] 10 1 0.1 [grad] ν θ 0.01 0.1 1 10 100 1000 t [s] 11 Puzzling Compact Star Phenomena - Quark Star Candidates? Quasiperiodic Brightness Oscillations (QPO’s) in Low-mass X-Ray Binaries (LMXB’s) ) Limits for Mass - Radius - Relation ) 2 M too large mass for quark stars? ( Rossi-XTE LMXB ) Gamma-Ray Bursts (GRB), extragalactic, extremely bright, Connection to Supernova Explosions ) Which Engine ∼ 1052 erg ? ( INTEGRAL GRB 990123 ) Isolated X-ray source (RX J18565), 17 km radiation radius ) too big for a Neutron Star? ( HUBBLE RX J1856.5-3754 ) Pulsar in Supernova Remnant (3C58; AD 1181) with Temperature T = 106 K ) too cold for a Neutron Star? ( CHANDRA 3C58 ) 12 Wide variety of supernovas - progenitor mass dependence 13 Supernova Collapse in the Phase Diagram 2 Supernova evolution 10 in the phase diagram [MeV] T Nuclear matter 101 temperature 2SC 100 108 109 1010 1011 1012 1013 1014 1015 density ρ [g cm-3] 14 Supernova Collapse in the Phase Diagram (II) 2 Supernova evolution 10 in the phase diagram [MeV] T Nuclear matter 101 15 Msun (Harald Dimmelmeier) temperature 2SC 100 108 109 1010 1011 1012 1013 1014 1015 density ρ [g cm-3] 15 Supernova Collapse in the Phase Diagram 2 40 Msun 10 (Tobias Fischer) [MeV] T 101 15 Msun (Harald Dimmelmeier) temperature 100 108 109 1010 1011 1012 1013 1014 1015 density ρ [g cm-3] 16 The case of SN2006gy 17 The case of SN2006gy - a Quarknova ? Light curve: 70 days rise time Discovery: Sept.
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