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

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Expanding cold front 1

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1 Thermal Evolution of Rotating Neutron Stars

Thermal Evolution of Rotating Neutron Stars

Thank you!