Anti-glitch induced by collision of a solid body with the magnetar 1E Y. F. Huang Collaborator: J. J. Geng Nanjing University

Outline 1. Background: glitches 2. Anti-glitch from 1E Our model: collision event 4. Discussion

Espinoza et al MNRAS 30 years timing history of PSR B

Espinoza et al MNRAS 4 large glitches in the Crab pulsar

Espinoza et al MNRAS More glitches

Espinoza et al MNRAS

Glitches of Magnetars RXS J and 1E Dib et al. 2008, ApJ

Shapiro & Teukolsky 2004

Explanations for glitches The origin is still debated: Superfluidity: interaction of quantized neutron vortex lines with the neutron-rich nuclear clusters in the inner crust (Pines & Alpar 1985; Negele & Vautherin 1973; Pizzochero 2011) Crust-cracking events (Ruderman et al. 1998) ? Pines & Alpar

Outline 1. Background: glitches 2. Anti-glitch from 1E Our model 4. Discussion

The Magnetar 1E P=6.979 s (v = Hz) d = 4+/-0.8 kpc A few history glitches observed 1E Credit: ESA/XMM-Newton/M. Sasaki et al.

History glitches: 2002 outburst 2002 outburst On June 18 Woods et al. 2004

History glitches: 9 years overview Icdem et al glitch Possible micro anti-glitch?

An anti-glitch in April 2012 Archibald et al. 2013, Nat.

Timing events in around April 2012

Model 1: Model 2: + + x 2 =45.4/44 x 2 =38.1/44 Archibald et al. 2013, Nat.

Model 1: Model 2: + + x 2 =45.4/44 x 2 =38.1/44 Archibald et al. 2013, Nat.

Model 1: +x 2 =45.4/44 A hard X-ray burst: Exb=1.1e38 erg (36ms, Fermi/GBM, keV) An X-ray afterglow: Ex=2.1e41 erg (2-10 keV, Fx ~ t ) Pulse profile: changed Foley et al. 2012

Possible models for anti-glitches Internal mechanisms Internal superfluid spins slower than the crust? (Thompson et al. 2000; Garcia & Ranea-Sandoval 2014, arXiv: ) External mechanisms Strong outflows (Tong 2013) Sudden twisting of magnetic fields (Lyutikov 2013) Accretion disk of retrograde matter (Katz 2013; Ouyed et al. 2013) Cannot explain the rarity or Not a sudden glitch, cannot explain the outburst.

Outline 1. Background: glitches 2. Anti-glitch from 1E Our model 4. Discussion

Our model: collision of a solid body with the magnetar Huang & Geng, ApJ, 2014, 782, L20 (arXiv: )

Our model: collision of a solid body with the magnetar Huang & Geng, ApJ, 2014, 782, L20 (arXiv: )

Colgate & Petschek 1981

Our model: collision process broken up distance: Collision duration: (Colgate & Petschek 1981) Huang & Geng, ApJ, 2014, 782, L20 (arXiv: )

Consistency with observations Association with an outburst Duration of the outburst (36ms) Energy release in the afterglow (2.1e41 erg) Amplitude of the anti-glitch ( ) Huang & Geng, ApJ, 2014, 782, L20 (arXiv: ) Credit: NASA

Outline 1. Background: glitches 2. Anti-glitch from 1E Our model 4. Discussion

Discussion: more collision events are possible The capture radius could be as large as: 20R ns R ns Tremaine & Zytkow 1986, ApJ

Collision possibility Asteroids disturbed by other planets? Oort-like cloud objects scatterd toward the NS? Collision of planets, generating small bodies? Neutron star escaping its original planet system? …… Collision rate: 1 per 5, e7 years for a single NS. (Mitrofanov & Sadgeev 1990)

Collision-induced glitches/anti-glitches Collision can produce either glitches or anti-glitches They can be either radiatively active or inactive Unlikely show any periodicity for a single NS More likely happen in young pulsars than old ones May have already been observed previously A new method to probe the capture events of neutron stars. Thank You!