No Longer!The Double Pulsar

Maura McLaughlinWest Virginia University

5 April 2012

Collaborators: Kramer (MPiFR), Stairs (UBC), Perera (WVU), Kim (WVU), Rosen (WVU), Lyutikov (Purdue), Lomiashvili (Purdue),

Gourgouliatos (Purdue), Breton (Southampton), Kaspi (McGill), Freire (MPiFR), Burgay (Cagliari), Ferdman (Manchester), Possenti (Cagliari), Lyne

(Manchester), Ransom (NRAO)

The Money Shot

Kramer et al. in preparation

Pulsar A BPeriod (ms) 22.7 2774

Stellar mass (⊙) 1.34 1.25Projected semi-major axis (lt-s) 1.4 1.5

Characteristic age (Myr) 210 150Surface magnetic field strength

(Gauss) 6x109 2x1012

Energy loss rate due to spin-down (erg/s)

5800x1030 2x1030

Distance (pc) 1150 1150Orbital inclination (degrees) 88.69 88.60

Orbital period (hours) 2.45 2.45Eccentricity 0.088 0.088

A B

Influence of B on A: Eclipses

A is eclipsed for ~ 30 seconds per orbit.

Occulting region of 0.05 lt-s; 10% of light-cylinder radius (~1010 cm) of B.

Can model eclipse shape to derive geometrical parameters of the system (α = 70o, θ = 130o) and measure 5o yr-1 rate of geodetic precession of B (Breton et al. 2008)

GBT @ 820 MHz

McLaughlin et al. 2004

Orbital phase (degrees)

Puls

ed fl

ux d

ensi

ty

Influence of B on A: Eclipses

A is eclipsed for ~ 30 seconds per orbit.

Occulting region of 0.05 lt-s; 10% of light-cylinder radius (~1010 cm) of B.

Pulsar B field is dipolar!

GBT @ 820 MHz

Orbital phase (degrees)

Puls

ed fl

ux d

ensi

ty

Influence of A on B: Bright Phases

Kramer and Stairs 2008

B bright at only two orbital phases.

GBT @ 820 MHz

B bright at only two orbital phases.

Due to A distorting B’s magnetosphere (Lyutikov 2005).

Influence of A on B: Bright Phases

Kramer and Stairs 2008

GBT @ 820 MHz

Bright phases evolve due to periastron advance (17o yr-1) and geodetic precession (5o yr-1) .

Influence of A on B: Bright Phases

Kramer and Stairs 2008

Light curves of B during BP1.

Perera et al. 2010

B shows dramatic pulse profile changes across orbit and with time.

March 2008: Bye Bye B

Geodetic Precession: Pulse Profiles

Pulse profiles of B during BP1Perera et al. 2010

We can fit the pulse profile evolution to a geometrical model. We find similar geometrical parameters as from eclipse model fitting (α = 70o, θ = 130o).

Emission beam is elliptical (a/b = 2.6) and only partially filled.

Radio reappearance is expected to occur in 2024.

Geodetic Precession: Pulse Profiles

Perera et al. 2010

Bow shock at 4 x 109 cm (30% RLC) from B. Can trace the magnetic field lines structure within this bow shock, given solved geometry. Will change with orbital phase and B spin phase.

Can estimate a magnetic field of 6 x 1011 G, half of timing-derived value.

Perera et al. submitted

Influence of A on B: Emission Heights

Influence of A on B: Emission Heights

Can estimate emission heights given magnetic field structure and shape of pulse profile.

Perera et al. submitted

Application: NS-NS Inspiral Rates

DP will merge in 85 Myr.

Can now incporate selection effects for B.

Kim et al. submitted

Application: NS-NS Inspiral Rates

DP will merge in 85 Myr.

There are roughly 1400(+4100,-900) DP-like systems in MW.

Given 445 Mpc horizon distance for Advanced LIGO, we calculate a detection rate of 8(+11,-5) yr -1.

Kim et al. submittedKim et al. submitted

J0737

B1534 B1913

Influence of A on B: Drifting Features

Single pulses from A

Single pulses from B

Drifting

GBT @ 820 MHz

McLaughlin et al. 2004

Influence of A on B: Drifting Features

The drifting is a direct signature of the influence on the EM radiation from A on B!

McLaughlin et al. 2004

Influence of A on B: Drifting Features

Response Delay =

Through a geometrical model (Freire et al. 2009, Rosen et al. in preparation), can fit for:

1) Rotation direction of A

2) Emission altitude in B, ε

3) Angle between A’s radio and EM beam, ϕe

Through a geometrical model (Freire et al. 2009, Rosen et al. in preparation), can fit for:

1) Rotation direction of A likely in direction of orbit

2) Emission altitude in B, ε ~500 RNS (within the bow shock)

3) Angle between A’s radio and EM beam, ϕe small and varying

Influence of A on B: Drifting Features

Response Delay =

Conclusions

After nine years, the Double Pulsar is still providing new insights.

We can fit B pulsar data with an elliptical, partially filled beam and can determine the geometrical parameters of the system.

B is expected to reappear in 2024.

We see evidence for the direct modulation of B pulsar emission through the EM field of A.

We estimate minimum B emission heights of ~100 RNS through geometrical modeling and ~500 RNS through drift-band fitting.

We estimate an Advanced LIGO NS-NS inspiral detection rate of 8(+11,-5) yr -1. More relativistic binaries essential for better statistics.

Advances in timing and GR tests will come with improved B timing precision.