Qiao,G.J. Dept. of Astronomy, Peking Univ.

Collaborators:Zhang, B.(University of Nevada), Xu, R.X.(PKU), Han,J.L.(NAOC), Lin,W.P.(SHO),Lee,K.J.(PKU)

Xia,X.Y.

Radio and Gamma-ray emission of pulsars

Radio and Gamma-ray emission of pulsars

I. Radio emission (Inverse Compton scattering model: ICS )

II. Inner annular gap & gamma-ray emission Radio + Gamma ray emission

III. Pulsar: Neuron stars or Strange stars?

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core gap Annular gap

Strange stars

Pulsar emission beams

Observations

Emission beams

Rankin, 1983, ApJ,274,333

Theories

Ruderman & Sutherland (RS) Model

Ruderman & Shutherland,1975, ApJ,196,51

Emission beams in RS model

Ruderman & Sutherland, 1975

Emission beams

Hollow cone only!

Obs. & Theory(ICS)

(1) Core + Cones (2) Different components come from different locations (3) Pulse profile shapes changing with freq. (4) Mode changing (5) Bi-drifting

Pulsars: NS or Strange stars?

ICS Model: emission beams Core +cones⇒

Qiao, 1992

ICS: shift of emission beams

Different emission location→shift ofthe emission beams

Qiao & Lin, 1998, A&A,333,172

Poln: Beam shift→PA jumps

Xu, Qiao & Han, 1997, AA

Poln: PA jump

Xu, Qiao & Han, 1997, AA

ICS model: inner gap sparking →ω0

ω=2γ2ω0(1-βCosθi)

Qiao & Lin, 1998, A&A

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core gap Annular gap

Strange stars

RS model

Qiao,Liu, Zhang,& Han, 2001,AALyne & Manchester (1988) & Sieber et al. (1975),Kramer,(1994)

“S” shape PA & Obs.

Poln of integrated pulse in ICS

V—circular poln

L—Linear poln

I—Total Intensity

Position angle

Xu,Liu,Han,Qiao, 2000, ApJ

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core gap Annular gap

Strange stars

Mode changing of pulsars

Rankin, 1986

Zhang,Qiao,Lin,Han, 1997

Tree mode of sparking

Thermal ICS

Curvature radiation

Resonant ICS

Mode change pulsars

Zhang,Qiao,Lin,Han, 1997,ApJZhang,Qiao, Han, 1997,ApJ

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core gap Annular gap

Strange stars

☆ Polar cap (polar gap)

Basic Observational facts vs Theories

☆Radio--- Gamma-rays:

Obs.

Outer gapGamma-ray Radio

The magnetosphere of a NS

+

Inner annular gap

Inner annular gap

Qiao,Lee,Wang,Xu, Han, 2004a,ApJL

Inner annular gap

Qiao,Lee,Wang,Xu, 2004a, ApJL

Inner Annular Gap

Qiao,Lee,Wang,Xu, 2004a, ApJL

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core gap Annular gap

Strange stars

Mclaughlin 2003,astr-ph/0310454

Bi-drifting: Obs.

Drifting subpulses

PULSE LONGITUDE

Drifting subpulses

Taylor et al. (1975) Backer (1973)

Accelerators:

• Inner vacuum gap (Ruderman & Sutherland 1975)

requiring high binding energy of charges on stellar surface

Drifting sub-pulses

Xu,Qiao Zhang,

1999,ApJL,522,L112

Deshpannde & Rankin,

1999,ApJ, 524,1008

Inner Annular Gap : V= c E x B / B^2

Bi-drifting: fitting

Mclaughlin 2003,astr-ph/0310454

Qiao,Lee,Zhang,Xu,Wang,2004b, ApJL

Neutron stars:

Binding energy ≤ 10 KeV no gap can be formed!!! Binding energy > 10 KeV only one gap cab be formed: core or annular gap

Strange stars:

both core & annular gap can be Formed !

● Annular Gap mole: different Gamma-ray pulsars can be fitted ● Pulsars: Strange stars?

● Observational check: Polarization at high energy bands ● Theory: two caps=two gap?

Conclusion and discussion

Core beamBeam-frequencyMode changing

Bi-drifting Gamma-ray

Core flow Annular flow

Neutron stars

?

??

Qiao,Lee,Zhang,Wang & Xu,,2005,

• Can free flow produce drifting pulses?

• If not, can we distinguish NS from SS?

♣ More drifting phenomena need to be obs.

♣ Sub-millisecond pulsar need to be found?

100 m telescope will be helpful for the research above!

?

100m at EffelsbergNew Green Bank Telescope

Jodrell Bank KaShi,China ?

Thank you !

Multi-cones in the ICS model

Qiao,Wang,Wang,Xu, 2002,ChJAA

Multi-frequency fitting of PSR J0437-4715

Qiao,Wang,Wang,Xu, 2002,ChJAA

Magnetosphere of pulsars

Goldreich & Julian (1969)

Charge density — ρGJ

(Goldreich & Julian 1969 )

]sin)/(1[

1

24 22

crc

BE

0

Bc

rE

0 BE

0 BE

GJ

GJ

0// E

0// E

Acceleration electric fieldAcceleration electric field

Inner annular gap

Qiao,Lee,Wang,Xu, Han, 2004

Ruderman & Sutherland, 1975

Neutron stars: binding energy > 10KeV

Can’t form core and annular gap at the same time!

Strange stars: binding energy << 10KeV

Can form core and annular gap at the same time!

Interstellar DispersionIonised gas in the interstellar medium causes lower radio frequencies to arrive at the Earth with a small delay compared to higher frequencies.

Given a model for the distribution of ionised gas in the Galaxy, the amount of delay can be used to estimate the distance to the pulsar.

P--period

DM--dispersion measure

msDMdt highlow 2261015.4

Crab pulsar

Vela Pulsar

Geminga

Inner annular gap

Qiao,Lee,Wang,Xu, 2003

PAjumps: individual pulses ???

Stinebring et at. 1984

OPM Depolarization (Xu.R.X)

Orthogonal Poln Mode (OPM) →Depolarization (Low LP] ???

Or

Low LP →OPM ???

Daugherty &

Lerche, 1975

2

4.4 4exp( ), 1

/ 3q

e

Ble c m c B

The “Death line” of radio pulsars

2

4.4 4exp( ), 1

/ 3q

e

Ble c m c B

h lB B B

1/ 24( / )

3Rc

2 22 (1 cos ) 2i mE

3.5 1.5 1ln ln

2AP P D P P

The Death line of radio pulsars

Death and appearance line

Qiao et al.,2003

Sparking condition !

Does not Hubble line!

The Death line of radio pulsars

Qiao & Zhang,1996

The magnetosphere of a NS

Critical field line

NCS

Low L Poln→OPM ?

Xu & Qiao, 2000, Science in China

Outer Gap Model

Emission beams:

1 &4 ： toward out side

2 & 3 ： toward inside

Muslimov & Harding, 2003

Slot gap model

Beams in ICS model

Type I

Type II

Qiao,Liu,Zhang & Han, 2001

Obs. & ICS : Type I a

Obs. ICS

Qiao,Liu, Zhang,& Han, 2001,AALyne & Manchester (1988) & Sieber et al. (1975)

Obs. & ICS: Type Ib

Obs. ICS

Qiao,Liu, Zhang,& Han, 2001,AAKramer (1994).

Obs. & ICS : Type IIa

ICS Obs.

Qiao,Liu, Zhang,& Han, 2001,AAPhillips & Wolszczan (1992).

Magnetospere of pulsars

Am--mass of ion, Z-charge of ion

Outer gap, 1

Space charge limited flow

Inner gap

Holloway 1975 MN

Poln. of Individual pulses in ICS model

Xu,Liu,Han,Qiao, 2000, ApJ

Radio emission of pulsars

Observations & Theories☆ Emission beams: Core+Cones Emission locations☆ Polarization: linear, circular, “orthogonal mode”☆ Pulse profiles changing with frequencies

Rankin (1983, 1993)

Gil & Krawczyk 1996;Mitra & Deshpande 1999;

Gangadhara & Gupta 2001,

Lyne & Manchester 1988

Han & Manchester 2001

Core and Cones

ω=2γ2ω0(1-βCosθi)

ICS model: The low frequency wave can Propagate near the surface

Qiao & Lin, 1998, AA

Polar Cap Model

Inner annular gap

Qiao,Lee,Wang,Xu, 2003

Gamma-ray +radio emission

Radio + Gamma ray emission model ☆ Basic picture ☆ Pulse profiles fitting: radio + Gamma-rays

Gamma-ray emission of pulsars

● Current models ☆ Polar cap model ☆ Outer gap model ● Radio + Gamma ray emission model ☆ Basic picture ☆ Pulse profiles fitting: radio + Gamma-rays

• Pulsars are broad-band emitters (gamma-ray, X-ray, optical, radio)

• Pulsars must be particle accelerators

• Two preferred acceleration regions:

--- Polar cap region --- Outer gap region

Pulsar Gaps

●

Gamma-ray OBS. Of Radio Pulsars

谢 谢 !

Janssenet al. astr-ph/0406484: PSR B1818-13