Qiaogj

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

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

Qiao,G.J. Dept. of Astronomy, Peking Univ. Radio and Gamma-ray emission from pulsars

Slide2: 

Collaborators: Zhang, B.(University of Nevada), Xu, R.X.(PKU), Han,J.L.(NAOC), Lin,W.P.(SHO), Liu,G.F.(CFA, Harvard) Xue,Y.Q.(Purdue Univ. ) Wang,H.G.(CFA , GuangzhouUniversity), Lee,K.J.(PKU)

Slide3: 

Pulsars are discovered 40 years Key problems: The nature of PSR:NS & Quark stars ? Radiation:radiation mechanisms? Polar gaps? Outer gaps? or … Annular gaps?

Slide4: 

Observations Radio Gamma-ray Annular gap Polar gap Theories Narrow Wide Outer gap Spect; Cut wide Plausible

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §3.Annular gap §4.Free flow: slot gap & Annular gap : 

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §3.Annular gap §4.Free flow: slot gap & Annular gap Radio and Gamma-ray radiation of pulsars

Emission beams: 

Emission beams Rankin, 1983, ApJ,274,333 Manchester,R.N. 1995 J. Astroph. Astr. 16,107 Core emission !

Slide7: 

Emission beams in RS model Ruderman & Sutherland, 1975 Emission beams Hollow cone only! Low freq: wide beam!

Slide8: 

RS model Qiao,Liu, Zhang,& Han, 2001,AA Lyne & Manchester (1988) & Sieber et al. (1975),Kramer,(1994) There are various beam width- frequency relations, which can not be simple explained by RS model. ?

ICS Model: emission beams ⇒ Core +cones: 

ICS Model: emission beams ⇒ Core +cones Qiao, 1992 Qiao & Lin, A&A,1998

Slide10: 

Zhang, Qiao, Han, Lee, Wang , AA,2007 Different components of same frequency come from different altitudes.

Slide11: 

Polarization: Beam shift→PA jumps Xu, Qiao & Han, 1997, AA

Slide12: 

Zhang,Qiao,Lin,Han, 1997 Rankin, 1986

Slide13: 

Mode change pulsars Zhang,Qiao,Lin,Han, 1997,ApJ Zhang,Qiao, Han, 1997,ApJ

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §2.Annular gap §3.Free flow: slot gap & Annular gap : 

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §2.Annular gap §3.Free flow: slot gap & Annular gap Radio and Gamma-ray radiation of pulsars

Slide15: 

The magnetosphere of a NS For Crab Pulsar:  Goldreich & Julian, 1969,ApJ,157,869

1. Gap:inner gap & outer gap 2. Space Charge Limited Flow: Polar cap; Slot gap 3. Annular gap: 

1. Gap:inner gap & outer gap 2. Space Charge Limited Flow: Polar cap; Slot gap 3. Annular gap The annular gap: the important region

Basic Observational facts: 

Basic Observational facts David J. Thompson:astro-ph/0312272

Slide18: 

For inner gap Phase resolved spectrum, bridge is hard 1e1~1e3 Gev cut-off For outer gap Wide beams Thompson, astro-ph/0312272 , Kanbach, 2002,astro-ph/0209021

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §3.Annular gap §4.Free flow: slot gap & Annular gap : 

§1.Radio obs. & theories: Sparking; annular emission §2.The magnetosphere & acceleration polar gap; outer gap §3.Annular gap §4.Free flow: slot gap & Annular gap Radio and Gamma-ray radiation of pulsars

Slide20: 

Two polar cap regions Core region Annular region Outer gap

Slide21: 

The Inner Annular Gap Qiao,Lee,Wang,Xu, 2004a, ApJL The radio and gamma-ray can be understood by annular gap at same time.

Slide22: 

Mclaughlin 2003,astr-ph/0310454 Bi-drifting: Obs.

Slide23: 

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 :: 

Inner Annular Gap :

Bi-drifting: fitting: 

Bi-drifting: fitting Mclaughlin 2003,astr-ph/0310454 Qiao,Lee,Zhang,Xu,Wang,2004b, ApJL

§1.The magnetosphere & acceleration polar gap: phase resolute spectrum,cut off outer gap: gamma-ray wide beam §2.Annular gap §3.Free flow: slot gap & Annular gap §4.Radio obs. & theories: Sparking; annular emission : 

§1.The magnetosphere & acceleration polar gap: phase resolute spectrum,cut off outer gap: gamma-ray wide beam §2.Annular gap §3.Free flow: slot gap & Annular gap §4.Radio obs. & theories: Sparking; annular emission Radio and Gamma-ray radiation of pulsars

The annular flow accelerator --Can particles be accelerated in the annular region (the non-vacuum gap cases)?: 

The annular flow accelerator --Can particles be accelerated in the annular region (the non-vacuum gap cases)? Qiao,Lee,Zhang,Wang,Xu, astro-ph/0704.3801

The annular gap: 

The annular gap the annular gap must be taking into account! ⇒

Slide29: 

Pulsars: NS or Quark stars ? Free flow: sparking or not ? Free flow: can produce drifting sub-pulse? Annular gap & others: Obs. Test? Future obs. & theories

Slide30: 

PSR B1055-52 : observational constraints

Position angle sweep fit with Rotation Vector Model: 

~157o Position angle sweep fit with Rotation Vector Model Lyne & Manchester 1988 Inclination Angle a Viewing Angle z a Line of Sight W m z Pole A (MP) Pole B (IP) MP IP Double-pole origin Wang et al.2005

Slide32: 

PSR B1055-52 : observational constraints 1). Inclination angle a=74.7 dgree 2). Viewing angle z =114 dgree

Slide33: 

Thompson et al. 1992 Radio Observed emission beams Gamma-ray

Slide34: 

Observed emission beams Wang et al.2005 From observation, the radiation location can be determined uniquely for this star.

Slide35: 

Annular emission model Wang et al.2005 The observations show that the radiation position locates in the annular region.

Slide36: 

Thank you !

Spark Model: 

Spark Model Gil & Sendyk, 2000

Qiao & Lin, A&A,1998: 

Qiao & Lin, A&A,1998 ICS: shift of emission beams Different emission location→shift of the emission beams

Slide39: 

ω=2γ2ω0(1-βCosθi) The Inverse Compton Scattering (ICS) model Qiao & Lin,1998, A&A

Slide40: 

Polarization of integrated pulse in ICS (Xu et al. ApJ.2000 ) V—circular poln L—Linear poln I—Total Intensity Position angle

Slide41: 

Polarization: PA jump Xu, Qiao & Han, 1997, AA

Xu et al. ApJ. 2000: 

Polarization of Individual pulses in ICS model Xu et al. ApJ. 2000

Pulsar radiation : 

Pulsar radiation Radio: w/P∼3-4% Gamma-ray: Two pulses & very wide

Slide44: 

“S” shape PA & Obs. → The radiation location: near surface

The annular gap: 

The annular gap

Slide46: 

Drifting subpulses PULSE LONGITUDE Drifting subpulses Taylor et al. (1975) Backer (1973)

Slide47: 

Slot gap

Slot gap model: 

Slot gap model Arons,J. 1983, ApJ

Slide49: 

McCullon et al. 1976 Observation at radio band

Slide50: 

Obs. Obs.

authorStream Live Help