1 / 51

High Energy Astrophysics

High Energy Astrophysics. § Radiative Processes. Kunihito IOKA (KEK) 井岡　邦仁. Radiative Processes. ISM Wind SN. Acceleration of Relativistic Jet G >>1. External Shock. Internal Shock. g -sphere t ~1. GRB Prompt AGN Blazar. Synchrotron Inverse Compton Bremss , e ± , …

dugan
Download Presentation

High Energy Astrophysics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. High Energy Astrophysics § Radiative Processes Kunihito IOKA (KEK) 井岡　邦仁

  2. Radiative Processes ISM Wind SN Acceleration of Relativistic Jet G>>1 External Shock Internal Shock g-sphere t~1 GRB Prompt AGN Blazar • Synchrotron • Inverse Compton • Bremss, e±, … • Hadron GRB Afterglow AGN Hotspot Microquasar PWN, SNR

  3. Synchrotron Sources GRB afterglow Galama 98; Panaitescu & Kumar 00; Yost+ 03; Price+ 03; De Pasquale+ 10; many others

  4. Synchrotron Sources AGN Blazar & Hotspot Fossati+ 97, 98; Kubo+ 98; Donato+ 01; Kino & Takahara 04, Stawarz+ 07; many others

  5. Synchrotron Sources Pulsar Wind Nebula Aharonian+ 98; Meyer+ 10; Tanaka & Takahara10, 11; many others

  6. Synchrotron Sources Supernova Remnant Giordano+ 11, Ohira+ 11; Abdo+ 10; many others

  7. Synchrotron Characteristic Frequency Eq. of motion unobservable Period

  8. Power & Spectrum Power Spectrum Volume/Time Energy density B sT Thompson Cross Section

  9. Electron Distribution Number per unit ge (p=2: Equal E per log bin)

  10. Lorentz Boost Blueshift Lab time t Com. t’=t/G Obs. tobs=t/G2 E/tobs=GE’/(t’/G) ∝ gm0 Blueshift Next we need G, Ne, B, gm

  11. GRB Afterglow • G (Bulk Lorentz factor) • Adiabatic, n=const, spherical: • Ne (Electron number) • B (Magnetic field) • Shock jump condition • A fraction of energy ⇒ B Given: T, E, n, dL, ee, eB

  12. GRB Afterglow • gm(Minimum Lorentz factor) • Shock jump condition • A fraction of energy⇒ Electron Given: T, E, n, dL, ee, eB

  13. GRB Afterglow Evolution ~Observations

  14. Jet Break • Adiabatic, n=const, jet Harrison+ 99 Achromatic Break Break time ⇒ Opening angle

  15. Cooling Electrons lose energy by synchrotron Injection rate of e Second derivation

  16. Fast Cooling ⇔ Slow cooling in previous case Electrons lose energy by synchrotron (stationary) Second derivation

  17. Self-absorption Black body Surface area

  18. Cooling & Self-absorption n ~GcT (Fn,max, na, nm, nc) ⇒ (E, n, ee, eB)

  19. Synchrotron Shock Model Sari, Piran & Narayan 98 (Fn,max, na, nm, nc) ⇒ (E, n, ee, eB)

  20. Zhang & Meszaros 03

  21. Min. Energy Requirement Synchrotron observables Total Energy useful for limited observations

  22. Reverse Shock Emission ISM Ejecta G Contact Discontinuity Reverse Shock Forward Shock Radius p, e 4 3 2 1 Radius G2>>1, if G34~1 ⇒ RS emission is soft (Density is high at RS ⇒ Low temperature) while e2=e3 ⇒ Total energy is similar

  23. Optical Flash GRB990123 ９等 Zhang+ 03 Provide information on ejecta ⇒ G0, B0 Fox+ 03 GRB021211 Sari & Piran99 But somehow rare

  24. Electron Distribution • Blazar/Hotspot • p~1.4-1.8 (<2) • ⇒ Need gmax or gbr • Pulsar Wind Nebula • p~1-1.6 (<2) • ⇒ Need gmax or gbr to determine Etot to determine Etot p~2-3 p~2-3 p~1-2 p~1-2 ~106 ~104-105 ~103-104 ~109 ⇒ Pulsar Wind G~106

  25. Synchrotron Model for GRB Prompt? Internal Shock ⇒ 1. Electron 2. Magnetic Field ⇒ Synchrotron c/sw/ observed Yonetoku relation? But DG usually destroy correlations

  26. Amati/Yonetoku Relation Ep~600keV L531/2 Large DG/G usually destroys a correlation Amati 02 Yonetoku+KI 03 ~Typical g Energy

  27. Synchrotron Death line n-1/2 Superposition of syn-spectrum Fn Forbidden n1/3 n w/ cooling (fast)

  28. Inverse Compton Blumenthal & Gold 70 Comoving Frame ~ge2n ge Photon ~gen n ~gen Electron Thompson scattering change E little Obviously nIC<gemec2 (Energy conservation)

  29. Cross Section n s [cm2] Klein-Nishina Formula/Suppression In e-moving frame,

  30. IC Power Power Ratio to synchrotron Volume/Time Energy density e e B sT Thompson Cross Section Syncrotron IC

  31. IC+Syn Cooling Electrons lose energy by IC & Synchrotron Injection rate of e Second derivation

  32. SSC (SynchrotronSelf-Compton) nFn Syn-emitting electrons upscattersyn-photons Syn IC n fraction of Ue that is radiated IC-to-Syn ratio Ratio x ⇒ Unique UB & Ue

  33. SSC Spectrum Coincide Copy ×gm2 Copy ×gc2

  34. SSC Maximum Frequency Copy ×gm2 Copy ×gc2

  35. Klein-Nishina Suppression E.g., if ⇒ Softer by n-1 Copy ×gm2 Copy ×gc2

  36. External Compton Assume isotropic diffuse radiation In jet-comoving, ⇒ Enhance IC Bulk Compton by cold electron Sikora+ 94

  37. Nonthermal from Thermal • Electronsw/ temperature kT (>mec2) • Photon energy amplification per scattering • After k scattering • Probability of k scatterings is ~tk (<1) • Emergent spectrum is ~kT Unsaturated Compton; Also nonrelativisitc case

  38. Thermalization Consider photons w/ energy E (<<mec2) in electron bath w/ temperature T (<<mec2) How long does it take for thermalizationE→kT? Energy shift per scattering ⇒ Need many scatterings Even if t>1, non-thermal spec. survives E+DE E kT

  39. e± Signatures Lithwick & Sari 01 Murase & KI 08 Aoi+ 10 Gmec2 Target g energy Not exp. but power-law by finite-/multi-zone & time-dependence effects Optical depth ⇒ Information of G

  40. CTA • ~20GeV-100TeV • x10 Sensitivity • Dq~1-2 min • FOV~5-10 deg • ~20 s slew (LST) • ~2015 (?) • ~150€ Large Effective Area ⇒ 100-10000 of GeV-TeVg

  41. Hadronic Emission: pp High energy p collide with ambient p

  42. pp Cross-Section & Multiplicity PDG 0912.0023

  43. Hadronic or Leptonic? Abdo+ 11 Funk 11

  44. Funk 11 Funk 11

  45. Funk 11 Funk 11

  46. Hadronic Emission: pg d-function approximation Bhattacharjee & Sigl 00

  47. Other Processes • Photopair process • Adiabatic loss • Coulomb collision • Bremsstrahlung • Nuclear g-ray line • Photonuclear reactions • EM Cascade • Proton, muon, … synchrotron • High B QED processes, …

  48. § Radiation Processes • Synchrotron • nm, nc (fast/slow), na • (Fn,max, na, nm, nc) ⇒ (E, n, ee, eB) • Inverse Compton • nIC~g2n • PIC/Psyn=Ug/UB (SSC), EC • e± signatures • Hadronic: pp, pg • Problem: Can index Fnsyn~n1/3 change?

  49. Jitter Radiation

  50. Backup

More Related