Double neutron star evolution from geometric constraints Robert Ferdman University of East Anglia Bonn NS Workshop X 14 November 2016
A tale of two DNSs PSR J0737-3039A/B J1756 2251 Spin period (s) 0.0227 / 2.77 0.0284 Pulsar/comp. mass (M ) 1.3381(7) / 1.2489(7) 1.341(7) / 1.230(7) Orbital/system parameters Orbital period (h) 2.45 7.67 Inclination ( ) 88.7 68.0 Eccentricity 0.0878 0.181 Trans. velocity (km/s) ~10 < 68 Compare with other DNS systems, e.g.: PSR B1534+12 PSR B1913+16 Eccentricity 0.27 0.62 Trans. velocity (km/s) 107 88
Geodetic precession Companion star perturbs spacetime around pulsar spin axis precesses about orbital angular momentum k δ K s 1 j Orbital plane J i δ: misalignment angle Plane of the sky line of sight varies over time pulse profile change I = i Observer line of sight RDF et al. (2013)
Geodetic precession Companion star perturbs spacetime around pulsar spin axis precesses about orbital angular momentum k δ K s 1 j Orbital plane J i δ: misalignment angle Plane of the sky line of sight varies over time pulse profile change I = i Observer line of sight RDF et al. (2013)
Geodetic precession PSR Precession Period (yr) δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 J0737 3039B 71 130.0(4) J1756 2251 496 J1906+0746* 165 89(-44, +85)
Geodetic precession B1534+12 PSR Precession Period (yr) B1913+16 δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 J0737 3039B 71 130.0(4) J1756 2251 496 J1906+0746* 165 89(-44, +85) (Stairs, Living Rev. Relativity 6, (2003), 5) (Taylor & Weisberg, 1989, ApJ, 345, 434; Weisberg, Romani, and Taylor, 1989, ApJ, 347, 1030; Kramer, 1998, ApJ, 509, 856)
Geodetic precession PSR Precession Period (yr) δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 Fit widths: J0737 3039B 71 130.0(4) beam region ½ opening angle pulse ½ width misalignment angle J1756 2251 (Rafikov & Lai 2006, ApJ, 641, 438) 496 J1906+0746* 165 89(-44, +85) (Damour & Taylor 1992, PRD, 45, 1840) spin/magnetic axis separation spin/los axis separation orbital inclination precession phase
Observations Green Bank Telescope 820 MHz J0737 3039: ~6 years (~8% P prec ) semi-annual concentrated campaigns 1-2 weeks x ~5-8 hr single-epoch combined profiles J1756 2251: ~9.5 years + Lovell ~2 years combined 6-month spans
PSR J0737 3039A RDF et al. 2013
PSR J0737 3039A RDF et al. 2013
PSR J1756 2251 RDF et al. (2014)
Precession and misalignment PSR Precession Period (yr) δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 < 3.2 J0737 3039B 71 130.0(4) J1756 2251 496 < 34 J1906+0746* 165 89(-44, +85)
Precession and misalignment PSR Precession Period (yr) δ( ) B1534+12 (years) 692 25(4) 95% B1913+16 298 18(6) J0737 3039A 75 < 3.2 J0737 3039B 71 130.0(4) RDF et al. (2014) J1756 2251 496 < 34 J1906+0746* 165 89(-44, +85)
Precession and misalignment PSR Precession 68% 95% Period (yr) δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 < 3.2 J0737 3039B 71 130.0(4) RDF et al. (2014) J1756 2251 496 < 34 J1906+0746* 165 89(-44, +85)
Precession and misalignment NEW from PALFA! { PSR Lazarus et al. (2016) { Precession Period (yr) δ( ) B1534+12 (years) 692 25(4) B1913+16 298 18(6) J0737 3039A 75 < 3.2 J0737 3039B 71 130.0(4) J1756 2251 496 < 34 J1906+0746* 165 89(-44, +85) J1913+1102 197? Pulsar mass: 1.65(5) Companion mass: 1.24(5) Eccentricity: 0.0895
PSR B1534+12 PSR B1913+16 High eccentricity Large transverse velocity Large spin-orbit misalignment Larger companion mass PSR J0737 3039 PSR J1756 2251 Low eccentricity Low transverse velocity Low spin-orbit misalignment Low companion mass High mass-loss Large pre-natal kick Asymmetric explosion Low mass-loss Low pre-natal kick Symmetric supernova event Type II SN VIOLENT CORE COLLAPSE Electron-capture SN Ultra-stripped Type Ic SN
Symmetric supernovae Electron capture: Secondary O-Ne-Mg core overcomes density threshold Electron degeneracy pressure Chandrasekhar mass Collapse! Faster than instability formation timescale Low kicks Critical mass for collapse B mass + binding energy Almost no mass ejected! Ultra-stripped Type Ic: Mass transfer from a He core to compact companion Very fast core collapse, low kick expected Very low ejecta mass Expected range of resulting NS similar to B pulsar and 1756 companion See Tauris et al. (2013), ApJ, 778, L23
Double neutron star evolution from geometric constraints Robert Ferdman University of East Anglia Bonn NS Workshop X 14 November 2016