Extragalactic Jets:Some Unaswered Questions and

the Prospects for GLAST

Roger BlandfordKIPAC

Stanford

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Some Pre-History

• 1918 Curtis: M87 Jet• 1943 Seyfert: AGN• 1939 Reber: Cyg A• 1953 Jennison & Das Gupta: Cyg A double• 1954 Baade & Minkowski: Cyg A ID• 1956 Burbidge: Energetics of M87• 1963 Hoyle & Fowler Gravitational Collapse• 1963 Swarup et al: Cyg A hotspots

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Some History

• 1963 Schmidt: 3C 273• 1964 Zeldovich, Novikov, Salpeter: Black Holes

• 1965 Dent: Variability of 3C 273• 1967 Rees: Relativistic expansion• 1967 Various: VLBI• 1969 Lynden Bell: Accretion Disks• 1971 Hargrave & Ryle: Cygnus A• 1971 Rees: Beam model of radio sources

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Primary Questions

• Prime Mover?

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Primary Questions• Prime Mover?

– Stars, superstars, supernovae, pulsars… holes

• Black Hole Engineering?– Energy flow: disks vs jets– Mechanism: (Electro)magnetic vs gas, Accretion vs spin?

• Galaxy Formation and Evolution– Mergers – AGN vs Starbursts– Jets vs winds– Feedback

• Environmental impact– (Re-)ionization– Cluster evolution…

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Observational Progress, Prospects

• FR1/2, SLE, core-jet… – Unification…

• Optical, IR, X-ray,-ray jets…– Non-EM (UHECR, GW, VHE ) limits?– 60-160 EGRET blazars, ~ 20 TeV BL Lacs

• AGN phenomenology– Grand unification?– Demography

• Massive Black Holes– M - relation– Spin?

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Theoretical Progress

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Jet-specific Issues• Anatomical

– Multi-frequency jet structure– Kinematics– Composition

• Physiological– Emission mechanisms– Pressures and powers– Confinement

• Sociological– Counts, LF, multivariate– Backgrounds

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Connecting to Primary Questions

• Inferences– Test Central Dogma:

• M’/M, M => AGN Taxonomy, Jet Properties, M => Scale?– Unify - remove orientation effects!

• Environment, history… of secondary importance

– Jet formation and collimation• Relate to GRB, XRB, PWN, YSO…

• Deductions– Power, thrust and composition– AGN role in galaxy evolution– Environmental impact

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Ten Challenges

1. Locate the sites of radio, emission2. Map jet velocity fields3. Identify the emission mechanism4. Understand the changing composition5. Measure external pressure6. Deduce jet confinement mechanism7. Infer jet powers, thrusts8. Test and apply central hypothesis9. BHGRMHD capability10.Quantify role in clusters

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1. Locate the sites of radio,

emission • Models

– One zone vs r<->E, • Map core, jet

?• Multiwavelength campaigns

– 3C279 etc– MKN 501 2 min at TeV energy

• opacity

• Statistical variability– Radio flux variation ~ GeV ~ TeV– Cross-correlate sample– Deduce ordering, indepedence

• Cause– BH vs environment vs local jet instability

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2. Map jet velocity fields • Lorentz boost is powerful amplifier– S ~ D3…– May see insignificant part of source

• Velocity shear is natural– Cores beamed away?– Jets decelerate

•FR2 vs FR1

• Essential for energetics– Statistical approaches?– GRBs?

~30c

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3. Identify the emission mechanism

• X-ray OK?– S vs EC-1 vs SC-1 vs CMBC-1

• Radio– Synchrotron radiation fits, but…– Evidence for intrinsic intraday variability

• Coherent emission– Cyclotron masers, current instabilities– Sun, Jupiter

• Sins of transmission vs sins of emission– Induced Compton, SRS…

• Gamma ray– Inverse Compton

• External vs internal

– Hadronic models• VHE detection

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4. Understand the changing composition

• What carries the power?– EM

• AC vs DC vs • Favorite near BH• Where do currents close?

– Hadrons • Ion plasma with ~ 10• VHE p (or n)

– Leptons (pair plasma)• Not close to BH

• Observational approaches– Faraday depolarisation– Bulk Comptonisation– …

B R2

V ~ I~ V / Z

0

P ~ V I

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5. Measure external pressure• Cluster X-ray emission

– Ambient n[r], T[r] =>P[r]– Cosmic ray partial pressure?

•Primordial•AGN produced

– Magnetic field

• Host galaxy ISM– X-rays– mm observations

•ALMA?

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6. Deduce jet confinement mechanism

• Ballistic propagation– Collimation at BH?– Hadronic models– Active collimation?

• Gas confinement– Equipartion pressures

• Magnetic Pinches– Relativistic Z-pinch

• Lmech~10LEM!

• Dipole vs Quadrupole

– RFP models…• Flux constraint, <B||

>~0

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On the Electrodynamics of Moving Bodies

Even field Odd current

Camenzind, Koide

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Pictor A

Current Flow

Nonthermal emission is ohmic dissipation of current flow?

Electromagnetic Transport1018 not 1017 ADC not ACNo internal shocksNew particle acceleration mechanisms

Pinch stabilized by velocity gradient

Equipartition in core

Wilson et al

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7. Infer jet powers, thrusts

• Jet measurements– Generally lower bounds

• Nature of Hot Spots– Multi-wavelength studies– Infer speeds– Dentist drills, splashes…

• Modeling of radio lobes– Mach number of external shock– Numerical simulation

• Time dependence?– tjet < tdisk?

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8. Test and apply “Central Dogma”

• EGRET– (-1) ~ 10-(6.7-4.7) cm-2 s-1 – ~100 blazars mostly FSRQ

• GLAST 2007? (-1) < 10-8.7 cm-2 s-1

– 103-4 blazars; not resolve bckgd– FR1s? M87

• Modes of accretion– Radiative efficiency, outflows

• Unification and evolution– FSRQ -> BL Lac?– Obscured vs unobscured AGN

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9. BHGRMHD capability• High dynamic range

– MRI simulations– Stable GR codes

• BL and KS!

– AMR implementation

• Global field structure– Radial vs vertical?

• Toroidal?

– Ergosphere vs disk?– Wind vs jet?

• Extra physics for wind

– Stability• Episodic outflow

– Dipolar vs quadrupolar

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10. Quantify role in clusters

• Sophisticated modeling– Chandra imaging– XMM spectroscopy

• Cooling gas “vanishes”– AGN heating?

– Lensing, SZ– Use for cosmography!

• Bubbles?– Stable interfaces?– Heating by wake

• Horizontal heat transport?• Sound / internal waves?

– BH mass constraint

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Ten Challenges

1. Locate the sites of radio, emission2. Map jet velocity fields3. Identify the emission mechanism4. Understand the changing composition5. Measure jet pressures6. Deduce jet confinement mechanism7. Infer jet powers, thrusts8. Test and apply central hypothesis9. BHGRMHD capability10.Quantify role in clusters