Transitional Millisecond pulsars as accretion probes Caroline D’Angelo, Leiden University August 3, 2014 Amruta Jaodand, Anne Archibald, Jason Hessels, Alessandro Patruno, Slavko Bogdanov

Magnetospheric Accretion B field Spin Period General picture: B, P_*, L(Mdot)

Magnetospheric Accretion B field Spin Period General picture: B, P_*, L(Mdot)

Magnetically Regulated accretion: what determines spin rate? Spin up: accretion Spin down: Magnetically-launched outflows? (AE Aqr) Pulsar wind? (Parfrey, Spitkovsky talks) Transferred to accretion disk? (This work) Behaviour depends on Magnetic field strength, Spin rate, Accretion rate

J1023+0038: Accretion Model Probe Known B, P* Known timing solution Reasonable estimate of accretion rate Accretion at “quiescent” luminosities Pulsations – surface accretion in “propeller” regime Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important From X-ray luminosity:

J1023+0038: Accretion Model Probe Known B, P* Known timing solution Reasonable estimate of accretion rate Accretion at “quiescent” luminosities Pulsations – surface accretion Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important

J1023+0038: Accretion Model Probe Known B, P* Known timing solution Reasonable estimate of accretion rate Accretion at “quiescent” luminosities Pulsations – surface accretion Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important SEE AMRUTA JAODAND’S TALK ON THURSDAY

Magnetospheric Accretion B field Spin Period General picture: B, P_*, L(Mdot)

What is accretion rate that sets inner disk edge at corotation? Magnetospheric Accretion B field Spin Period What is accretion rate that sets inner disk edge at corotation? General picture: B, P_*, L(Mdot)

The ‘Critical' accretion rate pressure balance; ξ < 1 for rotating thin disk Angular momentum balance; η < 1 describes torque efficiency Critical accretion rate uncertain by ~40 Boundary of accretion/propeller regime Estimate Mdot so that Rin = Rc, accretion vs. barrier UNCERTAIN, depends on: magnetic field structure, disc/field interaction, disc structure (virialized flow) Radial inflow vs. disk-like: RIAF constraint

The ‘Critical' accretion rate pressure balance; ξ < 1 for rotating thin disk Angular momentum balance; η < 1 describes torque efficiency What happens when rm > rc? Critical accretion rate uncertain by ~40 Boundary of accretion/propeller regime Estimate Mdot so that Rin = Rc, accretion vs. barrier UNCERTAIN, depends on: magnetic field structure, disc/field interaction, disc structure (virialized flow) Radial inflow vs. disk-like: RIAF constraint

Simulations often Show transient accretion Lii et al. 2014 Make a picture of propeller outflow

Efficiency of outflow Constraints on RIAF solution

Propeller Trapped disc Strong outflow dominates Weak outflow; gas accretes Narrow range of produce pulsations Pulsations to low accretion rates Accretion flow dominates emission Stellar surface dominates emission Luminosity drops rapidly as accretion rate declines Luminosity drops gradually

Transitional Pulsars can be used to test these models Propeller Trapped disc Strong outflow dominates Weak outflow; gas accretes Narrow range of produce pulsations Pulsations to low accretion rates Accretion flow dominates emission Stellar surface dominates emission Luminosity drops rapidly as accretion rate declines Luminosity drops gradually Transitional Pulsars can be used to test these models

Simulations of strong accretion outflows how much mass outflows? How energetic? How much angular momentum is lost? use MHD simulations (unfortunately M. Romanova & collaborators couldn’t come present), some numerical limitations, but rough idea of inflow vs. outflow see intermittent bursts of accretion on v. fast timescales (few rotation periods)  

Efficiency of propeller Constraints on RIAF solution

Efficiency of propeller Constraints on RIAF solution

J1023+0038: An amazinG PROBE of accretion models Low accretion state: propeller?, radiatively-inefficient?) Pulsations – surface accretion * Known B, P* Known timing solution Reasonable estimate of accretion rate** Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important From X-ray luminosity:

J1023+0038: An amazinG PROBE of accretion models Low accretion state: propeller?, radiatively-inefficient?) Pulsations – surface accretion * Known B, P* Known timing solution Reasonable estimate of accretion rate** Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important From X-ray luminosity:

Caveats * Pulsations = surface accretion? Energy budget does not exclude X-rays generated by pulsar spin down. Could unchanged spin down suggest disk stays outside Light Cylinder?

J1023+0038: An amazinG PROBE of accretion models Low accretion state: propeller?, radiatively-inefficient?) Pulsations – surface accretion * Known B, P* Known timing solution Reasonable estimate of accretion rate** Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important From X-ray luminosity:

J1023+0038: An amazinG PROBE of accretion models Low accretion state: propeller?, radiatively-inefficient?) Pulsations – surface accretion * Known B, P* Known timing solution Reasonable estimate of accretion rate** Why are tMSP unique? What do they tell us about accretion physics? –good estimate of magnetic field strength (radio dipole spindown), precise timing solution (measure spindown in accretion state) – luminosity, B field, rotation rate, main physical parameters constrained, can ‘test’ mag. Accretion models, J1023: see *no change*, seems pulsar wind still active, accretion/ejection not important From X-ray luminosity:

Caveats * Pulsations = surface accretion? Energy budget does not exclude X-rays generated by pulsar spin down. Could unchanged spin down suggest disk stays outside Light Cylinder? ** Is X-ray luminosity really a good probe of accretion rate? (generate luminosity from spin down, lose mass to outflows, uncertain bolometric corrections)?

Compare Spindown Predictions Measured spin change: Accretion torques add >10% to spin-down rate: Limit on spin down (from enhanced pulsar wind, disk interaction, magnetically-launched wind): Predicted spin down depends on: spin-down source model, critical accretion rate, observed accretion rate Add picture of propeller vs. trapped disk Spell out again uncertainty on accretion rate (based on luminosity), uncertainty on Mdot for Rm

J1023+0038: Limits on propeller SPIN Higher accretion rate thinner disk

J1023+0038: Limits on propeller SPIN Higher accretion rate thinner disk

CONstraints on trapped disk picture?

CONstraints on trapped disk picture?

CONstraints on trapped disk picture? Max spin down: ‘Typical’ values (assumed in DS10):

Constraints from outflows? Flat radio spectrum: evidence for a jet? (Adam Deller) Other outflows? (Hernandez-Santisteban, Knigge) Can energy/outflow rate be constrained? Deller et al. 2015 Picture of Deller result – a strong outflow(?), Knigge/student? Energetic constraints, angular momentum loss constraints?

How much field is open? Pulsar wind shielded from disc ? Open field line region should be ~5 times larger in accreting state How strong is radio outflow? Constraints on spin up/down, propeller vs. trapped disc. For ms pulsar

COnclusions Transitional MSPs offer strong constraints on magnetospheric accretion models J1023 spin-down identical to dipole case Strong outflow predicts larger spin-down than constrained Trapped disc can work, on edge of parameter space Constraint on open field line region? Is something else going on?