the magnetar primer shriharsh p. tendulkar california institute of technology s. r. kulkarni p. b....

The Magnetar Primer

Shriharsh P. TendulkarCalifornia Institute of Technology

S. R. KulkarniP. B. Cameron

S. Tendulkar, RRI 2013 2

The Neutron Star Household

• Pulsars (1967)• Soft Gamma Repeaters (1979)• Recycled Pulsars (MSPs etc) (1982)• Isolated Neutron Stars (1992-1996) • Anomalous X-ray Pulsars (1995)• Compact Central Objects (around 2003)• RRaTs (2006)

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Where does everything fit?

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SGRsAXPs

INSsRRaTsStandard

Issue Pulsars

MSPs


Where does everything fit?

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Magnetic Field Powered

Rotation Powered

“Accretion” Powered


AXPs

• Anomalous X-ray Pulsars

• LX ~ 1035-36 erg/s

• Lrot ~1032 erg/s

• No companions

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AXP 1E 2259+586 inside CTB 109


SGRs

• Soft Gamma Repeaters

• Short bursts:– 1042 ergs/s

• Giant flares– 2-500 x 1044 ergs– -29 mag!

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What is a magnetar?

• Highly magnetized NS– B ≈ 1015 G– Young– Slowly rotating (P ≈ 5-10 s)

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What is a magnetar?

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1 2

3 4

Scientific American 2003R. Duncan

AXPSGR


Reasons for high B

• Spin down (1979 burst)– 8 sec in 104 years

• Energetics– Variability– No baryons

• Magnetic Containment

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Magnetar vs Pulsar

• Low B field ‘magnetar’– SGR 0418+5729– B~7 x 1012 G

• Radio quiet, X-ray bright

• Unsteady pulses, ratty Pdot

• High B field pulsars– Few x 1013 G

• Radio bright, X-ray quiet

• Steady pulses, decline

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Open Questions

• Formation– B-field Dynamo vs Fossil– Progenitors:

• Mass, Spin, High B-field?

– Age– Kinematics (~1000 km/s?)– SN energies

• Evolution– Lifetime

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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)

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Astrometry

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Why Astrometry?

• Kinematics– Comparison to other NS groups

• Ages– Model free

• Progenitors/Birth-places

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• Challenges:– Can’t work in X-rays– Very few radio/IR counterparts


OIR Astrometry

• Hubble Space Telescope– Large FoV– Stable Distortion– Diffraction Limited

• Very precise astrometry!– ≈ 0.020 mas/yr over 7 years

(Kallivayalil et al. 2013)

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Challenges in AO astrometry

• Small FoV (10-40”)

• Anisoplanatism– Changing PSF

• Variable Performance– Atmosphere

dependent

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Optimal Astrometry

• Tip-tilt Anisoplanatism

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Sasiela 1994

Cameron et al. 2009


Performance

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Palomar 5-m telescope

Cameron et al 2009Measurement Noise Tip-tilt Anisoplanatism


SGR 1900+14

• Giant flare: 27th Aug 1998• d ≈ 12 kpc• OIR counterpart (Testa et al. 2008)

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40 arcsec

Cluster of Massive Stars(Vrba et al. 2000)

Turnoff mass≈ 17 M

(Davies et al. 2009)


SGR 1806-20

• Giant flare: 27th Dec 2004• d ≈ 15 kpc• OIR counterpart (Israel et al. 2005)

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Cluster of Massive Stars(Fuchs et al. 1999)

Turnoff mass≈ 50 M

(Bibby et al. 2008)


AXP 4U 0142+61

• Brightest AXP• d ≈ 3 kpc

• Counterpart (Hulleman et al. 2000)

• OIR pulsations (Kern & Martin 2002)

• No association13/02/13


AXP 1E 2259+586

• Center of CTB 109• d ≈ 3 kpc

• OIR counterpart (Hulleman et al. 2001)

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CTB 109


Results

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SGR 1900+14

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Galactic Rotation

Expected Progenitor Velocity

MeasuredMagnetarVelocity

Galactic Plane


SGR 1900+14

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Age = 6 kyrTC = 0.9 kyr

V = 130 km/s


SGR 1806-20

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Towards Galactic Center

V = 350 km/s


SGR 1806-20

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Tendulkar et al (2012)

Age = 650 ± 300 yrTC = 160 yr


AXP 1E 2259+586

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V = 160 km/s

Opposite to Galactic Center


AXP 1E 2259+586

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Current Center of CTB 109

Age = 14 kyr(Sasaki et al. 2013)

Center of explosion DEN

SE M

OLE

CULA

R CL

OU

DTendulkar et al. in prep


AXP 4U 0142+61

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V = 100 km/s


AXP 4U 0142+61

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Hunt for an association

Tendulkar et al. in prep


Magnetar Kinematics

Magnetar Vtan (km/s) Association Method Reference

AXP 1E 1810−197 212±35 – VLBI Helfand et al (2007)

AXP 1E 1547.0-5408 280±120 SNR G327.4-0.13

VLBI Deller et al (2012)

SGR 1900+14 130±30 Cluster LGSAO Tendulkar et al (2012)

SGR 1806-20 350±100 Cluster LGSAO Tendulkar et al (2012)

AXP 1E 2259+586 157±17 SNR CTB 109 LGSAO Tendulkar et al (subm)

AXP 4U 0142+61 102±26 – LGSAO Tendulkar et al (subm)

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Magnetar Kinematics

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Tendulkar et al. in prep

Matches the velocity distribution of normal pulsars (Hobbs 2005)


The NuSTAR Magnetar

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Timeline

• 24th April ‘13 SWIFT XRT brightening– 0.11 cts/s (1.3 x 1035 ergs/s)

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Timeline

• 24th April ‘13 SWIFT XRT brightening– 0.11 cts/s (1.3 x 1035 ergs/s)

• 26th April ‘13 SWIFT BAT flare– 32 ms, 2500 cts/s

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Timeline

• 26th April ‘13 SWIFT BAT flare– 32 ms, 2500 cts/s

• 26th April ‘13 NuSTAR ToO6 hr obs

– 3.76 sec period

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Timeline

• 26th April ‘13 NuSTAR ToO6 hr obs

– 3.76 sec period

• 29th April ‘13 Chandra position– 3” away from GC (0.1 pc)

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Timeline

• 29th April ‘13 Chandra position– 3” away from GC (0.1 pc)

• 4th May ‘13 NuSTAR– 7 hrs– Pdot = 6 x 10-12 s/s– B ~ 1.5 x 1014 G

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Timeline

• 4th May ‘13 NuSTAR– 7 hrs– Pdot = 6 x 10-12 s/s– B ~ 1.5 x 1014 G

• 6th May ’13 Paper to ApJL– Kaya Mori et al.

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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

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Astrometry

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Galactic Rotation

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• No quasars– Absolute astrometry is

challenging

• Model galactic rotation– Along line of sight– SDSS stellar density– Estimate bulk motion

• Progenitor Velocity

the magnetar primer shriharsh p. tendulkar california institute of technology s. r. kulkarni p. b....

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