The Magnetar Primer Shriharsh P. Tendulkar California Institute of Technology S. R. Kulkarni P. B. Cameron
The Neutron Star Household Pulsars (1967) Soft Gamma Repeaters (1979) Recycled Pulsars (MSPs etc) (1982) Isolated Neutron Stars ( ) Anomalous X-ray Pulsars (1995) Compact Central Objects (around 2003) RRaTs (2006) 13/02/13S. Tendulkar, RRI 20132
Where does everything fit? 13/02/13S. Tendulkar, RRI 2013 SGRs AXPs INSs RRaTs Standard Issue Pulsars MSPs 3
Where does everything fit? 13/02/13S. Tendulkar, RRI 2013 Magnetic Field Powered Rotation Powered “Accretion” Powered 4
AXPs Anomalous X-ray Pulsars L X ~ erg/s L rot ~10 32 erg/s No companions 13/02/13S. Tendulkar, RRI 2013 AXP 1E inside CTB 109 5
SGRs Soft Gamma Repeaters Short bursts: – ergs/s Giant flares – x ergs – -29 mag! 13/02/13S. Tendulkar, RRI 20136
What is a magnetar? Highly magnetized NS – B ≈ G – Young – Slowly rotating (P ≈ 5-10 s) 13/02/13S. Tendulkar, RRI 20137
What is a magnetar? 13/02/13S. Tendulkar, RRI Scientific American 2003 R. Duncan AXP SGR 8
Reasons for high B Spin down (1979 burst) – 8 sec in 10 4 years Energetics – Variability – No baryons Magnetic Containment 13/02/13S. Tendulkar, RRI 20139
Magnetar vs Pulsar Low B field ‘magnetar’ – SGR – B~7 x G Radio quiet, X-ray bright Unsteady pulses, ratty Pdot High B field pulsars – Few x G Radio bright, X-ray quiet Steady pulses, decline 13/02/13S. Tendulkar, RRI
Open Questions Formation – B-field Dynamo vs Fossil – Progenitors: Mass, Spin, High B-field? – Age – Kinematics (~1000 km/s?) – SN energies Evolution – Lifetime 13/02/13S. Tendulkar, RRI
Wider Relevance Neutron Star census – Millions might be floating around? – Star formation history etc. Fraction of short-hard GRBs (Ofek et al) – Rate of NS-NS mergers Energetic supernovae (Kasen & Bildsten 2010) 13/02/13S. Tendulkar, RRI
Astrometry 13/02/13S. Tendulkar, RRI
Why Astrometry? Kinematics – Comparison to other NS groups Ages – Model free Progenitors/Birth-places 13/02/13S. Tendulkar, RRI 2013 Challenges: – Can’t work in X-rays – Very few radio/IR counterparts 14
OIR Astrometry Hubble Space Telescope – Large FoV – Stable Distortion – Diffraction Limited Very precise astrometry! – ≈ mas/yr over 7 years (Kallivayalil et al. 2013) 13/02/13S. Tendulkar, RRI
Challenges in AO astrometry Small FoV (10-40”) Anisoplanatism – Changing PSF Variable Performance – Atmosphere dependent 13/02/13S. Tendulkar, RRI
Optimal Astrometry Tip-tilt Anisoplanatism 13/02/13S. Tendulkar, RRI 2013 Sasiela 1994 Cameron et al
Optimal Astrometry Use covariance information Position: p i = W d i d i = [x 0 -x i, x 1 -x i … y N -y i ] T for each epoch Choose weights W for lst. sq. optimization – Same weights for all epochs 13/02/13S. Tendulkar, RRI
Performance 13/02/13S. Tendulkar, RRI 2013 Palomar 5-m telescope Cameron et al 2009 Measurement NoiseTip-tilt Anisoplanatism 19
SGR Giant flare: 27 th Aug 1998 d ≈ 12 kpc OIR counterpart (Testa et al. 2008) 13/02/13S. Tendulkar, RRI arcsec Cluster of Massive Stars (Vrba et al. 2000) Turnoff mass ≈ 17 M (Davies et al. 2009) 20
SGR Giant flare: 27 th Dec 2004 d ≈ 15 kpc OIR counterpart (Israel et al. 2005) 13/02/13S. Tendulkar, RRI 2013 Cluster of Massive Stars (Fuchs et al. 1999) Turnoff mass ≈ 50 M (Bibby et al. 2008) 21
AXP 4U Brightest AXP d ≈ 3 kpc Counterpart (Hulleman et al. 2000) OIR pulsations (Kern & Martin 2002) No association 13/02/13S. Tendulkar, RRI
AXP 1E Center of CTB 109 d ≈ 3 kpc OIR counterpart (Hulleman et al. 2001) 13/02/13S. Tendulkar, RRI arcmin CTB 109
Results 13/02/13S. Tendulkar, RRI
SGR /02/13S. Tendulkar, RRI 2013 Galactic Rotation Expected Progenitor Velocity Measured Magnetar Velocity Galactic Plane 25
SGR /02/13S. Tendulkar, RRI 2013 Age = 6 kyr T C = 0.9 kyr V = 130 km/s 26
SGR /02/13S. Tendulkar, RRI 2013 Towards Galactic Center V = 350 km/s 27
SGR /02/13S. Tendulkar, RRI 2013 Tendulkar et al (2012) Age = 650 ± 300 yr T C = 160 yr 28
SGR /02/13S. Tendulkar, RRI
AXP 1E /02/13S. Tendulkar, RRI 2013 V = 160 km/s Opposite to Galactic Center 30
AXP 1E /02/13S. Tendulkar, RRI 2013 Current Center of CTB 109 Age = 14 kyr (Sasaki et al. 2013) Center of explosion DENSE MOLECULAR CLOUD Tendulkar et al. in prep 31
AXP 4U /02/13S. Tendulkar, RRI 2013 V = 100 km/s 32
AXP 4U /02/13S. Tendulkar, RRI 2013 Hunt for an association Tendulkar et al. in prep 33
Magnetar Kinematics MagnetarV tan (km/s)AssociationMethodReference AXP 1E 1810−197212±35 –VLBIHelfand et al (2007) AXP 1E ±120SNR G VLBIDeller et al (2012) SGR ±30ClusterLGSAOTendulkar et al (2012) SGR ±100ClusterLGSAOTendulkar et al (2012) AXP 1E ±17SNR CTB 109LGSAOTendulkar et al (subm) AXP 4U ±26 –LGSAOTendulkar et al (subm) 13/02/13S. Tendulkar, RRI
Magnetar Kinematics 13/02/13S. Tendulkar, RRI 2013 Tendulkar et al. in prep Matches the velocity distribution of normal pulsars (Hobbs 2005) 35
The NuSTAR Magnetar 13/02/13S. Tendulkar, RRI
Timeline 24 th April ‘13 SWIFT XRT brightening – 0.11 cts/s (1.3 x ergs/s) 13/02/13S. Tendulkar, RRI
Timeline 24 th April ‘13 SWIFT XRT brightening – 0.11 cts/s (1.3 x ergs/s) 26 th April ‘13 SWIFT BAT flare – 32 ms, 2500 cts/s 13/02/13S. Tendulkar, RRI
Timeline 26 th April ‘13 SWIFT BAT flare – 32 ms, 2500 cts/s 26 th April ‘13 NuSTAR ToO 6 hr obs – 3.76 sec period 13/02/13S. Tendulkar, RRI
Timeline 26 th April ‘13 NuSTAR ToO 6 hr obs – 3.76 sec period 29 th April ‘13 Chandra position – 3” away from GC (0.1 pc) 13/02/13S. Tendulkar, RRI
Timeline 29 th April ‘13 Chandra position – 3” away from GC (0.1 pc) 4 th May ‘13 NuSTAR – 7 hrs – Pdot = 6 x s/s – B ~ 1.5 x G 13/02/13S. Tendulkar, RRI
Timeline 4 th May ‘13 NuSTAR – 7 hrs – Pdot = 6 x s/s – B ~ 1.5 x G 6 th May ’13 Paper to ApJL – Kaya Mori et al. 13/02/13S. Tendulkar, RRI
Implications Very similar to other magnetars Probably born in O/WR stars – 6 Myr old 40 M More evidence for “transient” magnetars – Link to high-B pulsars 13/02/13S. Tendulkar, RRI
Astrometry 13/02/13S. Tendulkar, RRI
Galactic Rotation 13/02/13S. Tendulkar, RRI 2013 No quasars – Absolute astrometry is challenging Model galactic rotation – Along line of sight – SDSS stellar density – Estimate bulk motion Progenitor Velocity 45