What Can Neutron Stars Tell Us about QED and Vice Versa? 17 April 2018 Ilaria Caiazzo, Roberto Mignami, Roberto Taverna, Roberto Turolla, Silvia Zane, and others.
Outline Birefringence Magnetars X-ray Pulsars
Birefringence An Old Prediction
Birefringence An Old Prediction
Birefringence An Old Prediction
Birefringence Index of Refraction n = 4 10 24 T 2 B 2 What could be a signature of this birefringence? A time delay: t 10 3 R/c 10ns? n n 10 9 10 8 10 7 10 6 10 5 10 4 10 3 10 2 10 1 10 11 10 12 10 13 10 14 10 15 10 16 Magnetic Field [Gauss]
Birefringence Index of Refraction n = 4 10 24 T 2 B 2 What could be a signature of this birefringence? A time delay: t 10 3 R/c 10ns? This seems a bit too subtle. n n 10 9 10 8 10 7 10 6 10 5 10 4 10 3 10 2 10 1 10 11 10 12 10 13 10 14 10 15 10 16 Magnetic Field [Gauss]
Liquid Crystal Displays
Liquid Crystal Displays Wikipedia
Polarization-Limiting Radius The radius at which the polarization stops following the birefringence is called the polarization-limiting radius. Beyond here the modes are coupled.
Polarization-Limiting Radius The radius at which the polarization stops following the birefringence is called the polarization-limiting radius. Beyond here the modes are coupled. The polarization-limiting radius for a dipole field is r pl ) 2/5 ( α ν ) ( 1/5 µ sin β 45 c B QED ( ) 1.9 10 7 µ 2/5 ( ) E 1/5 10 30 G cm 3 (sin β) 2/5 cm, 4 kev
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03 r pl /R = 1.9 (AM Her, AMSP)
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03 r pl /R = 12 (XRP)
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03 Quasi-Tangential Region Wang, Lai 09 r pl /R = 12 (XRP)
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03
Why does this matter? r pl /R = 0 Heyl, Shaviv, Lloyd 03 r pl /R = 76 (Magnetar)
Places to Look Radius Magnetic Field µ 30 r pl at 4 kev Magnetar 10 6 10 15 10 33 3.0 10 8 XRP 10 6 10 12 10 30 1.9 10 7 ms XRP 10 6 10 9 10 27 1.2 10 6 AM Her 10 9 10 8 10 35 1.9 10 9
Deep in the atmosphere of the neutron star the plasma dominates, while outside the vacuum dominates. For large strengths of the magnetic field, the vacuum resonance may lie between the photospheres B B l 6.6 10 13 T 1/8 6 E 1/4 1 S 1/4 G where S = 1 e E/kT. This can have a strong effect on the appearance of spectral features and the high-energy slope. Ho, Lai 04
Magnetars X-ray Pulsars Magnetar Emission Caiazzo & Heyl 2016; 4U 0142+61 Taverna et al. 2016; SGR 1806-20 (350ks)
To Do #1 Outline Magnetars X-ray Pulsars Simulate with XIPE QED effects from thermal Realistic Hydrogen Atmosphere and Astrophysics of Strong Magnetic Field systems with ext component of Physics the atmosphere, and combine Heyl, Shaviv, Lloyd 03 for ure 15:Linear The expected fraction of linear polarization from the surface neutron polarization hydrogen atmospheres withoftstrongly =106.5magnetized K neutron starsstars andwith eff 6.5 rogenmagnetic atmospheresmoment and e ective temperatures of 10 K. (from Heyl et al. 2005). 30 degrees from the line of sight (astro-ph/050235)
Magnetars X-ray Pulsars RX J1856.5-3754 Mignami et al. 2016
Magnetars X-ray Pulsars Her X-1 Polarization Degree 0.25 0.20 0.15 0.10 0.05 0.00 0.05 0.10 9 km 10 km 11 km 12 km 15 km Q/I [ Polarization Degree ] 0.20 0.15 0.10 0.05 0.00 0.05 9 km 10 km 11 km 15 km extp 100ks 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Energy [kev] 2 3 4 5 6 7 8 Energy [kev] Caiazzo & Heyl 2017
y Outline Magnetars X-ray Pulsars Her X-1 Polarization Degree 0.25 0.20 0.15 0.10 0.05 0.00 0.05 0.10 0.10 0.05 0.00 0.05 0.2 0.3 0.4 0.5 0.6 x 9 km 10 km 11 km 12 km 15 km Q/I [ Polarization Degree ] 0.20 0.15 0.10 0.05 0.00 0.05 9 km 10 km 11 km 15 km extp 100ks 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Energy [kev] 2 3 4 5 6 7 8 Energy [kev] Caiazzo & Heyl 2017
Places to Look Radius Magnetic Field µ 30 r pl at 4 kev Magnetar 10 6 10 15 10 33 3.0 10 8 XRP 10 6 10 12 10 30 1.9 10 7 ms XRP 10 6 10 9 10 27 1.2 10 6