1. A brief review of double-pulsar system, PSR J0737-3039
Burgay et al. (2005) ApJ 624, L113
Kaspi et al. (2004) ApJ 613, L137
Lyne et al. (2004) Science 303, 1153
McLaughlin et al. (2004) ApJ 616, L131
I’m very happy to be here and would like to express my special thanks to Bronek, who invited me to this academic institution for two weeks.
Today, I’d like to give a talk on the gamma-ray emission from pulsar outer magnetospheres.

2. Double-pulsar system J0737-3039
Double neutron star binaries are rare (7 confirmed).
Table: Observed double neutron star binaries
PSR eccen. a(Ro) Porb(days) period(ms)
J , 2773 J B J J J B
The only
binary
pulsar
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …
Catherine et al. (2006) ApJ 652, 540

3. Double-pulsar system J0737-3039
Doppler variations of P from J
→ double pulsar system
The double pulsar system J is
extremely compact (Porb=2.45 h),
mildly eccentric (e =0.088),
highly inclined (a =87.8o-89.6o).
Burgay et al. 2003, Nature 426, 531
Lyne et al. 2004, Science 303, 1153
The radio lightcurves show eclipse (by edge-on geom.).
Kaspi et al. 2004, ApJ 613, L137
Laboratory for magneto-ionic properties of a pulsar magnetosphere.

4. Evolution of the double-pulsar system
Consider a binary evolution scenario of two massive MS stars.
After a first mass transfer stage, the primary (more massive star) form a NS in a core-collapse supernova (Type II) explosion.
Under favorable conditions (small kick), the NS remains bound.
As the secondary evolves to a red giant, mass accretion takes place in an HMXB phase.
The accretion spins up the NS into millisecond period in years, dramatically reducing its magnetic field (to <1010G).
In a close binary, the secondary’s envelop enlarges to meet the NS to spirals in. The common envelop material expelled from the system, carrying most of the angular momentum, thereby significantly reducing the binary separation.
The very compact binary consists of a NS and a He star.
A sufficiently massive He star undergoes a core-collapse supernova explosion, leaving a young secondary NS.
Let us first briefly review the formation scenario of a double pulsar system.

5. Evolution of the double-pulsar system
Comparison of the two NSs:
Primary NS Secondary NS
comment recycled young
rotation period ~ 30 ms ~ 1000 ms
period derivative, Pdot ~ s s-1 ~ s s-1
characteristic age ~ 500 M years ~ 20 M years
P/(2*Pdot)
surface B field <1010G ~1012G
1019.5(P Pdot)0.5G
Because of this large lifetime difference, double pulsar binaries are rare.
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …

6. Double-pulsar system J0737-3039
J is the most extreme relativistic binary system ever discovered (Porb=2.45 h), with a remarkably high value of the periastron advance (dw/dt = 16.9o/yr).
Observational summary
pulsar PSR J A PSR J B
period ms ms
period derivative 1.75*10-18 s s *10-16 s s-1
eccentricity/dist / 600 pc
characteristic age 210 M years 50 M years
surface B 6.3*109 G 1.2*1012 G
spin-down lumino. 6*1033 ergs s-1 2*1030 ergs s-1
stellar mass (Mo) 1.337(5) (5)
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …

7. Probing pulsar magnetosphere
Because of the edge-on viewing angle (a ~88o), pulsar A experiences
a short eclipse by B’s magnetosphere due to synchrtrotron absorption.
Eclipse ingress takes
3.5 times longer than
egress, independent
of radio frequency.
Fig: Pulsar A eclipse
light curves. The
vertical solid line
denotes conjunction.
Kaspi et al. (2004)
ApJ 613, L137
27s (FWHM)
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …

8. Probing pulsar magnetosphere
When pulsar B is at longitude 270o (at superior conjunction),
A’s beam pass within
0.07 lt-s of pulsar B,
which is much smaller
than B’s light cylinder
radius, 0.45 lt-s.
Relative transverse
velocity ~ 680 km s-1
Eclipse duration ~ 60s
→ size~18,000 km
(0.060 lt-s)
~ impact parameter
(0.07 lt-s)
Lyne et al. (2004) Science 303, 1153
longitude=180o
top view
obs.
longitude=90o
longitude=0o
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …
B’s unperturbed
magnetosphere
(not to scale)
obs.
1~3o
side view

9. Probing pulsar magnetosphere
A’s transmitted pulsed flux modulates by the rotation of pulsar B.
1st eclipse
barycentric arrival time
of B’s pulses
(calculated)
2nd eclipse
3rd eclipse
rotational period of B
During the eclipse, …
2.8s
sum
(offset
corrected)
McLaughlin et al. (2006)
ApJ 616, L131

10. Probing pulsar magnetosphere
Dividing each 2.8 s window of B’s rotational phase into four equal regions, they calculated averaged light curves for each region (bottom fig.).
→ smooth light curves
Symmetric when B axis of B phases us or A.
Asymmetric when it is at right angles to the l. o. s.
McLaughlin et al. (2006)
ApJ 616, L131
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …

11. Synchrotron absorption model
Since A’s luminosity is about 3000 times greater than B,
A’s pulsar wind likely blow away B’s magnetosphere.
The bow shock compress wind plasma, leading to
a sharp jump in plasma
density and temperature.
→ synchrotron absorption.
magnetosheath
wind of A
magnetopause B A
to Earth
To begin with, I’d like to briefly review what is known and what is unknown in pulsar high-energy astrophysics.
Let me remind you that in a gamma-ray sky pulsars are point-like component …
Eclipse is symmetric when B’s
B axis is along the line of sight.
McLaughlin et al. (2004)
ApJ 616, L131
bow shock

12. One more issue …
Moreover, there exists three other candidate pulsars having statistical probability occurring by chance is about …
They are B reported by …

13. Pulsar B shows pulsed intensity variations
Pulsed radio flux from B increases systematically by almost two orders of magnitude during two short portions of its orbit. Lyne et al. (2004) Science 303, 1153
bright peak 1
bright peak 2
Moreover, there exists three other candidate pulsars having statistical probability occurring by chance is about …
They are B reported by …
one orbital revolution

14. Secular change of B’s pulse shape
bright peak 1
bright peak 2
The pulse shape of B secularly evolves.
18 months

15. Secular change of B’s pulse shape
The centroid of bp2 and the beginning of bp1 advance in orbital longitude at 3o/yr, while the centroid of bp1 does not move.
Bp2 centroid
Moreover, there exists three other candidate pulsars having statistical probability occurring by chance is about …
They are B reported by …
Bp1 beginnig

16. Secular change of B’s pulse shape
Is the advance of bp2’s centroid and bp1’s beginning (3o/yr) due to the geodesic precession (5.1o/yr) of B’s rotation axis with respect to the orbital angular momentum axis?
If so, B’s spin axis should be misaligned to the orbital angular momentum axis.
Periastron advance (17o/yr) appears to be unrelated…
Since pulsar A does not show evolution in its pulse shape or radio flux, A’s spin axis may be aligned to the orbital angular momentum axis.
Moreover, there exists three other candidate pulsars having statistical probability occurring by chance is about …
They are B reported by …

17. Jump-start model for B’s pulsed emission
It is still difficult to interpret the secular evolution of B’s pulse shape; however, excitation of B’s pulsed emission could be understood by a toy model. Lorimer (2004) Nature 428, 900

18. Summary
Still lots of things to do on this exciting double pulsar system.
What is known: binary separation, eccentricity, viewing angle
periastron advance (→ test of GR)
gravitational readshift
NS masses (1.33, 1.25 times solar masses)
A’s spin axis (parallel to orbital ang. mom.)
What is unknown: B’s spin axis (not parallel to orbital ang. m.)
B’s jump-start mechanism (stimulated PC?)
A’s eclipse (bow shock? hot closed zone?)