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.

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) J0737-3039 0.088 0.610 0.102 22.7, 2773 J1518+4904 0.249 8.634 8.634 40.9 B1534+12 0.274 1.606 0.421 37.9 J1756-2251 0.181 1.187 0.320 28.4 J1811-1736 0.828 14.982 18.779 104.1 J1829+2456 0.139 3.117 1.176 41.0 B1913+16 0.617 1.009 0.323 59.0 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

Double-pulsar system J0737-3039 Doppler variations of P from J0737-3039 → double pulsar system The double pulsar system J0737-3039 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.

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 106-107 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.

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 ~ 10-18 s s-1 ~ 10-15 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 …

Double-pulsar system J0737-3039 J0737-3039 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 J0737-3039A PSR J0737-3039B period 22.7 ms 2773 ms period derivative 1.75*10-18 s s-1 8.81*10-16 s s-1 eccentricity/dist. 0.0877 / 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) 1.250(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 …

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 …

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

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

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 …

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

One more issue … Moreover, there exists three other candidate pulsars having statistical probability occurring by chance is about … They are B0656+14 reported by …

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 B0656+14 reported by … one orbital revolution

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

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 B0656+14 reported by … Bp1 beginnig

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 B0656+14 reported by …

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

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?)