Introdution JRGI Radiation Mechanism Summary A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN Dmitry Khangulyan, ISAS/JAXA (Japan) in collaboration with F.Aharonian, M.Barkov, S.Bogovalov and S.Kelner High Energy Phenomena in Relativistic Outflows III Barcelona, June 27 – July 1 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 1 / 23
Introdution JRGI Radiation Mechanism Summary Outline Introduction: Fast Gamma Ray Variability in AGN Blob Fomation Process: JRGI scenario Mechanism at work: Scenario related Constrants on Radiation Mechanism Summary: Specific case of PKS A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 2 / 23
Introdution JRGI Radiation Mechanism Summary VHE o bservation of fast transients in AGNs HESS observation of PKS2155-304 τ ≈ 200 s − 1 L γ ≈ 10 47 erg s − 1 L X ≈ 10 46 erg s − 1 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 3 / 23
Introdution JRGI Radiation Mechanism Summary Causality Constraint Proper Variability Minimum variability time-scale τ ′ = ∆ r ′ c Observer Variability τ = ∆ r ′ Γ( 1 − cos θ ) c δ − 1 = 10 − 2 ∆ r ′ ≈ 6 × 10 14 cm A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 4 / 23
Introdution JRGI Radiation Mechanism Summary What are the Blobs in Powerful Jets? There are a lot of hypothetical blobs Internal Shocks, Magnetic Reconnection, Change in Accretion, Instabilities.... A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 5 / 23
Introdution JRGI Radiation Mechanism Summary Fundamental Requirements on the blob properties BLOBS MUST BE SMALL AND CONTAIN A LOT OF ENERGY (OR BE ABLE TO TRIGGER POWERFUL INTERACTION) instabilities accretion can be very small hydrodynamical scale a lot of energy no energy shocks reconnection very intensive interaction a lot of energy at hydrodynamical scale hydrodynamical scale A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 6 / 23
Introdution JRGI Radiation Mechanism Summary Typical Hydrodynamical Length Scale HD scale is determined by r g and Γ j τ > r g Γ ⇒ M BH < 10 7 M ⊙ (e.g. Levinson&Bromberg, 2008) δ c = Light black hole launch extremely powerful jets? Blazars with short VHE variability powered by double black holes? (e.g. Rieger&Mannheim, 2002) These are possible options, but not necessary... A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 7 / 23
Introdution JRGI Radiation Mechanism Summary Blobs of external origin If blobs have external origin, they can be very small as compared to the hydrodynamical scale of the jet.... External blobs contain no energy (as compared to the jet) I.e. external blobs must be able to trigger an intensive interaction . To be heavy? Compact and heavy, i.e DENSE: stars? Specific realization of such blob formation: Jet-Red Giant Interaction Scenario A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 8 / 23
Introdution JRGI Radiation Mechanism Summary Jet Red Giant Interaction Scenario (JRGI) Sketch of the scenario Necessary Elements Powerful jet dyn P ram ≃ 10 3 L j , 46 z − 2 17 θ − 2 − 1 cm 2 A Red Giant in the jet vicinity ∆ M ≈ 6 × 10 28 L j , 46 z − 2 17 θ − 2 − 1 g similar models: Barkov et al (2010); Araudo et al (2010) A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 9 / 23
Introdution JRGI Radiation Mechanism Summary If Ablated, then Trapped and Accelerated Important Stages Sketch of the scenario Jet Crossing Time t jc ≈ 2 . 5 × 10 7 z 3 / 2 17 θ − 1 M − 1 / 2 BH , 8 s Expansion t exp ≈ 5 × 10 7 R − 1 / 2 M 1 / 2 c , 30 L − 1 / 2 j , 46 z 17 θ − 1 s ∗ , 2 M c , sc � 3 × 10 29 L j , 46 R ∗ , 2 z 17 M − 1 BH , 8 g Acceleration M c , jc � 2 . 5 × 10 31 L j , 46 r 2 c , 15 M − 1 BH , 8 g ∆ M ≈ 6 × 10 28 L j , 46 z − 2 17 θ − 2 − 1 g A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 10 / 23
Introdution JRGI Radiation Mechanism Summary JRGI is very SHORT, apparently Apparent intensity Dynamics of the Cloud Blob move relativistically Motion of the Cloud � � − Γ 2 L j r 2 d Γ c 1 c c = Γ 4 dt Γ 2 4 ω 2 c 2 M c c j Analytical approximation � 1 � D dg g 2 − g 2 dy = � 1 � 1 y 2 F = g 4 g 2 − g 2 y 2 L j r 2 c D ≡ . 4 θ 2 Γ 3 j z 0 c 3 M c t 0 ≈ 60 Γ j , 1 . 5 L − 1 j , 46 M c , 25 s A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 11 / 23
Introdution JRGI Radiation Mechanism Summary JRGI can appear very BRIGHT Apparent intensity Energy Budget Luminosity r 2 L γ = 4 Γ 2 c j ξ FL j ω 2 Size of the Cloud � L γ, 47 r c ≈ 5 × 10 14 M BH , 8 cm L j , 46 ξ − 1 � 1 � 1 F = g 4 g 2 − g 2 L max = 2 × 10 48 ξ − 1 L j , 46 Γ 2 j , 1 . 5 erg s − 1 y 2 E tot ≈ 10 50 ξ − 1 M c , 25 Γ 3 j , 1 . 5 erg t 0 ≈ 60 Γ j , 1 . 5 L − 1 j , 46 M c , 25 s A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 12 / 23
Introdution JRGI Radiation Mechanism Summary Variability Pattern: fast cooling is required Causality Limit τ > r c Γ j c ≈ 4 × 10 2 z − 1 / 2 L 1 / 2 γ, 47 L − 1 / 2 j , 46 ξ − 1 / 2 M 3 / 2 BH , 8 s 17 − 1 Interaction Duration τ ≈ 2 z 2 0 θ 2 Γ j c 2 M c τ ≈ 60 Γ j , 1 . 5 L − 1 j , 46 M c , 25 s r 2 L j c Change of Doppler Factor τ ≈ 2 r c v s δ � 5 × 10 4 M BH , 8 L 1 / 2 γ, 47 L − 1 / 2 j , 46 ξ − 1 / 2 δ − 1 s − 1 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 13 / 23
Introdution JRGI Radiation Mechanism Summary General Framework: Magnetically Driven Jets Structure of the Jet Γ j ≈ ω B j ≈ 120 L 1 / 2 17 L 1 / 2 j , 46 z − 1 17 θ − 1 − 1 G B c ≈ 12 z − 1 4 r g j , 46 G A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 14 / 23
Introdution JRGI Radiation Mechanism Summary Synchrotron Self Compton: does NOT work in JRGI � 1 / 2 B 0 = 0 . 7 ν 2 P ram , SSC ≈ 2 × 10 − 3 ν 4 � E γ, 11 dyn 16 16 γ = 5 × 10 4 E γ, 11 δ E γ, 11 cm ν 16 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 15 / 23
Introdution JRGI Radiation Mechanism Summary External Inverse Compton L 1 / 3 j , 46 M 1 / 3 BH , 8 E 4 / 3 3 × 10 3 s z 7 / 4 γ, 11 z 17 ≫ 17 t ′ cool = ν 2 / 3 ( 1 + f ) L 3 / 4 j , 46 M 1 / 4 BH , 8 ν 1 / 2 16 16 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 16 / 23
Introdution JRGI Radiation Mechanism Summary Klein-Nishina: severely absorbed KN ≈ 10 2 τ 2 Γ j s τ γγ ≈ 40M BH , 8 L j , 46 z − 2 t ′ 17 likely a general problem (Derishev, 2010) A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 17 / 23
Introdution JRGI Radiation Mechanism Summary Proton Synchrotron: in Powerful Jets Maximum Energy E γ, 11 ≈ 1 B 2 E 2 19 E γ, max ≈ 400 η − 1 δ GeV Hillas Criterion z 3 / 2 17 L − 1 / 2 γ, 47 L − 1 / 4 j , 46 η − 1 / 2 ξ 1 / 2 − 1 M − 1 BH , 8 < 0 . 2 1 Cooling Time τ psyn ≈ t sy δ ≈ 2 × 10 4 η 1 / 2 M 1 / 2 BH , 8 z 17 L − 3 / 4 s j , 46 1 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 18 / 23
Introdution JRGI Radiation Mechanism Summary EIC Models for PKS Parameter Space Constraints 1 L j , 46 > 0 . 5 ξ − 1 M BH , 8 Γ 2 j , 1 . 5 L j , 46 > 10 M 2 BH , 8 Γ − 2 j , 1 . 5 ξ − 1 − 1 BH , 8 Γ 10 / 3 M 2 j , 1 . 5 L j , 46 > 0 . 007 τ 4 / 3 ν 2 / 3 2 16 M 2 BH , 8 Γ 6 j , 1 . 5 ν 2 16 L j , 46 ≪ 0 . 4 E 4 11 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 19 / 23
Introdution JRGI Radiation Mechanism Summary Proton Synchrotron Models for PKS Parameter Space Constraints 1 L j , 46 > 0 . 5 ξ − 1 M BH , 8 Γ 2 j , 1 . 5 BH , 8 Γ − 2 j , 1 . 5 ξ − 1 L j , 46 > 10 M 2 − 1 BH , 8 Γ 8 / 3 M 2 j , 1 . 5 L j , 46 > 500 τ 4 / 3 2 A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 20 / 23
Introdution JRGI Radiation Mechanism Summary Conclusion Short variability ⇒ external origin of the blobs Jet – star interaction can be a feasible origin of blobs RG can loose a large amount of material from atmosphere Interaction of (powerful) jets with the ablated atmosphere is likely lead to a formation of blobs Emission triggered by a blob may appear very short SSC and EIC(Klein-Nishina) do not work EIC(Thomson) or proton synchrotron may readily provide required flux level and variability timescale A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 21 / 23
Introdution JRGI Radiation Mechanism Summary For non-blazar AGNs: observation of M87 (Raue, in prep) A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 22 / 23
Introdution JRGI Radiation Mechanism Summary For non-blazar AGNs: lightcurve of M87 (Barkov et al., in prep) A POSSIBLE SCENARIO of FORMATION of GAMMA RAY EMITTING BLOBS in AGN 23 / 23
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