General Relativity and Neutron Stars - III Rodrigo Negreiros – UFF - Brazil Different manifestations “rotation powered pulsars” • Spin-down due to magnetic field torque. • Kinetic energy is (mostly) converted to magnetic dipole radiation. • Period range from seconds to ms. • ~ 2000 known pulsars. • ~ 100 x-ray pulsars. • ~ 130 gamma-ray pulsars. • At least one white-dwarf pulsar. Magnetic Braking Model • For magnetic dipole radiation (n =3) • Characteristic age A few observed data- RPP Deviation from magnetic braking model • Multipolar electromagnetic radiation (n ≥ 5) • Quadrupolar gravitational radiation (n =5) • Magnetic field decay (n > 3) • Relativistic winds n < 3, • Growth of submerged magnetic field in the stellar crust, due to hypercritical accretion. (n < 3) (Muslimov & Page 1996, Bernal et al. 2010, 2013, Pons et al. 2012) • Modification to the moment of inertia (n < 3) (Glendenning 2003, F. Weber 2010) Magnetars • Luminosity exceeds the spin-down energy loss. • Sub-categorized in Anomalous X-ray pulsars (AXPs) e Soft-Gamma Ray Repeaters (SGRs) • Irregular high energy bursts. • Relatively high temperatures • Most likely powered by very high magnetic fields. Magnetars – few observed data Central Compact Objects (CCOs) • Central objects found in supernovae remnants. • Radio silente, X-ray bright. • Continuous x-ray flow, predominantly thermal. • Absence of pulsar wind nebula. CCO’s – few observed data • Most CCO’s are well modeled by a one or two component BB - Tbb = (2 – 7) x 10^6 K. • Estimated emission radius of Rbb ~ (0.3 – 5) km. Isolated Pulsars(INS) • Also labeled XDINS (X-ray dim Isolated Neutron Stars) • Similar to CCOs, except they are not associated with Supernovae remnant. • Emission almost exclusively thermal (soft X-ray), with dim optic/UV counterpart. • 7 Confirmed INS– The Magnificent 7! INS – Few observed data Accreting Neutron Stars • Binary systems whose emissions are powered by accretion. • Categorized as ➢Low Mass X-ray Binaries ➢Intermediate X-ray Binaries ➢High Mass X-ray Binaries • Possible precursors to milisecond pulsars Neutron Star Cooling • Provides an additional tool for probing the composition of compact stars. • Allow us to make use of a wealth of observed data. Microscopic Equation of State Macroscopic composition structure Thermal Evolution Neutron Star Cooling • Cooling is dominated by neutrino emission • Magnitude of emissivity strongly depends on composition. • Thermal evolution is also influenced by macroscopic properties. Compact Neutrinos Stars Photons Neutron Star Cooling • Neutron stars cool inside out! Neutron Star Cooling – Possible structures Neutron Star Cooling – Possible structures Neutron Star Cooling – Thermal equations • Relativistic equation for energy balance and transport. Microscopic Macroscopic Properties properties Neutron Star Cooling – “ingredients” • Macroscopic Ingredients ➢Radial distance ➢Mass profile ➢Pressure profile ➢Density Profile ➢Curvature • Microscopic Ingredients ➢Thermal conductivity ➢Specific Heat ➢Neutrino Emissivity ➢Photon Emissivity ➢Pairing Neutron Star Cooling – Neutrino Emissivities Core Crost Direct Urca process Electron Bremsstrahlung Modified Urca process e+e- Annihilation Bremsstrahlung Plasmon Decay Neutron Star Cooling – Fast/Slow Core-Crust thermal coupling τc ~ 100 years Slow Fast R. Negreiros, V.A. Dexheimer, S. Schramm, Phys.Rev.C 82, 035803 (2010) Neutron Star Cooling – Fast/Slow • Direct Urca Process leads to fast cooling Threshold: Proton fraction ~ 11 – 15 % Pairing Neutron Star Cooling Hadronic stars HV Hadronic stars HV G300 Neutron Star Cooling Hybrid Stars • Recall the composition R. Negreiros, V.A. Dexheimer, S. Schramm, Phys.Rev. C 82, 035803 (2010) Hybrid Stars R. Negreiros, V.A. Dexheimer, S. Schramm, Phys.Rev. C 82, 035803 (2010) Hybrid Stars • How importante is the quark core? Hybrid Stars Negreiros, Dexheimer, Schramm, Phys.Rev.C 85, 035805 (2012) Hybrid Stars Negreiros, Dexheimer, Schramm, Phys.Rev.C 85, 035805 (2012) Hybrid Stars Model A Negreiros, Dexheimer, Schramm, Phys.Rev.C 85, 035805 (2012) Neutron Star Cooling Quark Stars • Superconducting quark matter • Neutrino emission suppresion Quark Stars • Vortex expulsion Evolução Térmica– Estrelas de Quarks • Soft Gamma-Ray Repeaters (SGR´s) e Anomalous X-Ray Pulsars (AXP´s) • Emissão de flashes irregulars e ultra-energéticos de radiação X e Gamma • Temperaturas observadas muito altas. Negreiros et al; Phys.Rev.D81:043005,2010 Evolução Térmica– Estrelas de Quarks Negreiros et al; Phys.Rev.D81:043005,2010 Thermal Evolution of Rotating Neutron Stars • Traditional Approach Spherically Symmetric “Frozen-in” composition • Introduce a dynamic composition • Go beyond spherically symmetric scenario Thermal Evolution of Rotating Neutron Stars • Thermal Equations Negreiros, Schramm and Weber, Phys.Rev. D85 (2012) 104019 Thermal Evolution of Rotating Neutron Stars Mg = 1.48, ec = 350 MeV/fm³, freq = 750 Hz Polar hot spot ~80 years Negreiros, Schramm and Weber, Phys.Rev. D85 (2012) 104019 Axis-symmetric thermal evolution Negreiros, Schramm and Weber, Phys.Rev. D85 (2012) 104019 Thermal Evolution of Rotating Neutron Stars 1 Thinner crust on poles Thicker crust on equator 1 Expanding cold front 1 1 1 1 1 1 1 1 Thermal Evolution of Rotating Neutron Stars Thermal Evolution of Rotating Neutron Stars Thank you!.