Observing Rotation-powered Pulsars and Magnetars in the X-ray and Gamma-Ray Sky Wim Hermsen SRON Netherlands Institute for Space Research, Utrecht & Astronomical Institute Anton Pannekoek, Univ. of Amsterdam Cargese, 13-14 April 2006 Observing Rotation-powered Pulsars and Magnetars in the X-ray and Gamma-Ray Sky PART 1 • Population of Rotation-powered Pulsars and Magnetars • Rotation-Powered Pulsars - Status and Recent X-ray and Gamma-Ray Observations: Normal and millisecond pulsars - Review Emission Models, Comparison with Observations 2 Population of Rotation-powered Pulsars and Magnetars 3 Rotating Neutron Stars • Rotation-powered pulsars (mostly Radio Pulsars): . 34-38 -1 Ltot(EB) < Espin-down = E ~ 10 erg s • Magnetars: Soft Gamma-Ray Repeaters (SGRs) Anomalous X-ray Pulsars (AXPs) 33 -1 Ltot(EB) >> Espin-down ~ 10 erg s 36 -1 LX up to ~ 10 erg s (0.2 – 10 keV) 44 -1 LX/γ up to ~10 erg s in peak of giant SGR outburst 4 (Thompson & Duncan 1992; 1993; 1995;1996) 5 Rotation-Powered Pulsars and Magnetars RP Pulsars Magnetars Spinning-down neutron stars Similarities P ~ 1.5 ms – 8 s P ~ 5-11 s Pulsed high-energy emission Particle acceleration Glitches No bursts Bursts Differences Weak X-ray for same Ps Strong X-ray Radio No radio Rotation power Magnetic power 6 Pulsar Characteristic Parameters • Period P . • Period derivative P .. • Rotational energy loss E = IΩΩ I moment of inertia, Ω = 2π/P Ω . Light α • Spin-down flux F = E / 4πd2 Cylinder B d distance polar . cap • Characteristic age тc = P/2P • Open field line voltage . V = 4x1020 P-3/2P1/2 V null charge surface PC Ω . B = 0 closed field region • Averaged magnetic field strength at neutron star surface . 19 ½ BS = 3.3 x 10 (PP) (assuming simple magnetic dipole braking in vacuum) 7 Rotation-Powered Pulsars and Magnetars: . P–P diagram with B0 = Bs -9 • ~1500 radio pulsars 10 15 G -10 1 0 14 • ~30 X-ray pulsars G -11 • 10 γ-ray pulsars 1 0 13 G • 7 AXPs -12 B • 5 SGRs -13 0 = 5 SGRs 1 0 12 G -14 -15 1 0 11 Extreme B fields: G -16 14 15 derivative) Log (Period • AXPs & SGRs 10 –10 G -17 Radio pulsar AXP -18 8 10 SGR • Millisecond pulsars 10 –10 G Radio quiet pulsar HE pulsar -19 1 (old “recycled” pulsars, 0 10 G spun-up by accretion torques -20 10 9 in a binary system) G -3 -2 -1 0 1 2 Log[Period (s)] 8 Rotation-Powered Pulsars and Magnetars: . P–P diagram with BS, тC, VPC 10-9 1014 gauss 10-10 17 16 10 V 10 V 15 -11 10 V 14 10 10 V 1013 gauss High-confidence & -12 } 10 12 lower-confidence detections of 10 gauss 1013V high-energy (>100 MeV) 10-13 103 y gamma-ray pulsars -14 10 1012V . 104 y 10-15 5 10-16 10 y dP/dt P = (s/s) dP/dt 106 y 10-17 107 y -18 11 10 10 gauss 108 y Millisecond pulsar 10-19 10 PSR J0218+4232 10-20 10 gauss 109 gauss 10-21 0.001 0.010 0.100 1.000 10.000 P (s) 9 Rotation-Powered Pulsars - Status and Recent X-ray and Gamma-Ray Observations: Normal and millisecond pulsars 10 Crab and Vela profiles: Gamma rays (COS-B) down to the radio ≥ 25 years ago ! For 30 years Polar Cap models v.s. Outer Gap models ! Progress in our understanding of the production of non-thermal X- ray and gamma-ray emission in pulsar magnetospheres has ben slow. Particularly, because of the slow advance made in the observations. 11 Geometries of high-energy emission pulsar models Ω Light Cylinder α B polar cap slot gap null charge surface outer Ω . B = 0 closed field gap region 12 Gamma-ray pulsars • CGRO (20 keV-30 GeV) heritage: number of γ-ray pulsars increased from 2 (Crab, Vela) to 7 (10) • (10) include with lower significances also: PSR B0144+59, PSR B0656+14, PSR J0218+4232 (ms-psr!) • All relatively young (≤ few 100 kyr) and energetic • Established Galactic γ-ray source population, emitting over a wide high-energy range (0.5 keV – 10 GeV) Thompson, Harding, Hermsen, Ulmer, 1997 13 The seven highest-confidence gamma-ray pulsars on an EGRET all-sky map for E>100 MeV 14 The seven highest-confidence gamma-ray pulsars Crab B1509-58 Vela B1706-44 B1951+32 Geminga B1055-52 Radio ? Optical Soft X-Ray X-ray/ Gamma Ray Hard Gamma Intensity variation during one rotation of the neutron star neutron the of rotation one during variation Intensity Ray P ~ 33 ms P ~ 150 ms P ~ 89 ms P ~ 102 ms P ~ 39 ms P ~ 237 ms P ~ 197 ms djt 3/03 15 Multiwavelengths spectra of pulsed emission • Power peakes in γ-rays (hard X-rays for Crab) • No pulsed emission above 20 GeV • High-energy turnover • Middle-aged pulsars show multiple thermal X-ray components: cool BB T ~ 0.5 – 1 MK hot BB T > 1MK (old+msp) • For young pulsars non-thermal X-rays dominate Thompson, Harding, Hermsen, Ulmer, 1997 16 Correlation studies: Are they meaningfull using this small sample? 100 29 Crab Crab 28.5 L ~ E • J1513−5908 ∼ ergs/s 10 L E 28 γ psr • 34 B1509-58 J1709−4429 L ∝ E1/2 γ psr B1706-44 27.5 L ~ V ~ E1/2 J1048−5832 J1952+3252 B1046-58 27 Vela 1 J0218+4232 Vela B1951+32 26.5 ) over 1 sr, in W γ J1057−5226 J0218+4232 26 Geminga 0.1 log(L B1055-52 25.5 High-energy luminosity 10 luminosity High-energy Geminga J0659+1414 Assuming 1 steradian solid angle 25 0.01 24.5 B0656+14 27 28 29 30 31 32 1014 1015 1016 1017 log(dE /dt) in W psr Open Field Line Voltage V (4 x 1020 P-3/2 P1/2) . -3 LX ~ 10 E (with large scatter) For all model scenario’s measured values depend strongly on combination of inclination angle α between magnetic. and rotation axes, as well as the observers viewing angle ζ 17 Non-Thermal X-ray Detected Rotation-Powered Pulsarsa Recent compilation byKaspi Kaspi 18 Thermally Cooling Young Rotation-Powered Pulsarsa Recent compilation by Kaspi Most X-ray pulsars detected in “classical” X-ray range below 10 keV. 19 Observational gap between 10 keV and 100 MeV Crab Deep searches in archives and possibilities for currently operational missions. Detection of only four normal pulsars published: Crab PSR B1509-58 (not above 100 MeV) Vela PSR B0540-69 (not above 50 keV) Models are still mostly verified on Crab and Vela results, but not using all details! 20 Crab: Phase-Resolved Spectroscopy Crab 1st Peak P1 Bridge Emission 2nd Peak P2 Kuiper et al. 2001 E (MeV) 21 Vela pulse profiles from radio up to high-energy gamma rays Phase-resolved spectroscopy? Hermsen & Kuiper 2006, in prep. A&A Pk1 Pk1 Pk2 ? Pk3 Pk4 22 Vela Pulsar in the Ultraviolet (Romani, Kargaltsev, Pavlov 2005) Pk 1 Pk2 Pk3 Pk4 ► UV profiles also show sharp pulses Opt (~1 ms) for Pk2/soft, Pk3, Pk4 3.8-8.9 eV ► UV pulse at phase 1st Optical pulse (UV absolute ► New soft X-ray pulse (200-800 eV) phase uncertain) at phase 0.78 NOT in UV (< 11 eV) ► Pk4 (~ radio phase) Compton 7.1-10.9 eV up-scatter of radio photons from center of polar cap? OR Pk4 ~ at phase of giant micro pulses, similar to PSR J1937+21, 4-8 keV PSR B1821-24 and Crab: giant radio pulses at phases of non-thermal X-ray pulses 23 • Vela: Extremely structured high-energy phase histogram challenging the competing models • Are all light curves this structured in the X-ray range? • No, but we badly need more examples! Particularly to bridge the high-energy gamma-ray (> 100 MeV) results to the classical X-ray range below 10 keV • Middle-aged pulsars are very weak hard X-ray emitters. 24 Rotation-Powered Young Pulsars • Three young pulsars (< 10 kyr) at hard X-rays/soft γ-rays (CGRO/RXTE/BeppoSAX): PSR B0531+21 (Crab) PSR B1509-58 PSR B0540-69 (“twin” of Crab in LMC) • Different lightcurve shapes 25 Rotation-Powered Young Pulsars • Three young pulsars (< 10 kyr) at hard X-rays/soft γ-rays (CGRO/RXTE/BeppoSAX): PSR B0531+21 (Crab) PSR B1509-58 PSR B0540-69 (“twin” of Crab in LMC) • HE-spectra are different from older γ-ray pulsars ― Lx/Lγ larger ! 26 Increased Sample of Young Rotation-Powered Pulsars emitting at hard X-ray energies (Kuiper & Hermsen in prep.20prep.2006)06) ¾ We selected radio-dim/quiet young rotation-powered pulsars located in/near SNR’s: PSR J1846-0258 (Kes 75) PSR J1930+1852 (G54.1+0.3) PSR J1811-1925 (G11.2-0.3) PSR J1617-5055 (near RCW 103) ¾ Use of archival RXTE, BeppoSAX and ASCA data ¾ Follow-up with study with INTEGRAL 27 PSR J1846-0258 in SNR KES 75 ¾ Discovered by Gotthelf et al. (2000) in RXTE and ASCA ddataata ¾ “Slow” 324 ms pulsapulsar;r; Characteristic age : 723 year ¾ Radio quiequiett rotation powered pulsar ¾ In centre of SN-remnant Kes-75 (G29.7-0.3) (Chandra ACIS; Helfand et. al. 2003) 28 X-ray timing of the Kes-75 pulsar • PSR J1846-0258 monitored regularly by RXTE PCA since its discovery • Archival ASCA and BeppoSAX data • Baseline ~9.2 y : 10-10-1993 _ 25-01-2003 • Pulse period optimization per sub- observation using Z2-statistics 29 PSR J1846-0258 timing model 2 2 • Quadratic fit with ν0 ,dν0/dt and d ν0/dt yields accurate fit 2 parameters (χ r of 1.28; d.o.f.