Cherenkov & Jansky: Our Understanding of AGN at the Highest - - PowerPoint PPT Presentation

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Cherenkov & Jansky: Our Understanding of AGN at the Highest - - PowerPoint PPT Presentation

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Cherenkov & Jansky: Our Understanding of AGN at the Highest Energies Jeremy S. Perkins (CRESST/UMBC/GSFC) on behalf of the VERITAS and Fermi LAT Collaborations Wednesday, November 9, 2011 VHE: E > 100 GeV Necessarily ground based -

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SLIDE 1

Cherenkov & Jansky: Our Understanding of AGN at the Highest Energies

Jeremy S. Perkins (CRESST/UMBC/GSFC) on behalf of the VERITAS and Fermi LAT Collaborations

Wednesday, November 9, 2011

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SLIDE 2

VHE: E > 100 GeV

  • Necessarily ground based - cannot get

enough effective area with space based instruments (Effective Area ~ Football Field.

  • Uses some type of Cherenkov technique:

Air (atmosphere) or Water

  • Three major arrays:

VERITAS, HESS, MAGIC

  • Upgrades done or are happening: MAGIC2,

HESS2, VERITAS Upgrade

  • New generation coming soon: HAWC, CTA

Wednesday, November 9, 2011

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SLIDE 3

Over 120 VHE Sources, About 40 Blazars

http://tevcat.uchicago.edu

Wednesday, November 9, 2011

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SLIDE 4

4C +21.35 M87 3C279 PKS1510-089 Centaurus A NGC1275

6 ‘misaligned’ AGN

Wednesday, November 9, 2011

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SLIDE 5

Active Galactic Nuclei @ VHE

  • AGN “Standard Model”: Black Hole and

Accretion Disk Power Relativisitc Jet

  • Viewing Angle Determines Source Type
  • Open Questions
  • Emission Mechanisms?
  • Jet Structure?
  • Black Hole Accretion?
  • Leptonic or Hadronic?
  • Emission Region?
  • EBL?
  • Quantum Gravity?

Image: Aurore Simonnet, Sonoma State University Illustration: Robert Naeye, NASA GSFC

Black Hole Torus of Neutral Gas and Dust Accretion Disk Radio Jet

“Blazar” Viewing down the jet

Wednesday, November 9, 2011

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SLIDE 6

Why only a handful of misaligned Blazars?

Urry & Padova (1995)

Blazars Radio Galaxies

  • Blazars benefit from high

doppler factors and gammas.

  • Jet emission possible at

large theta but less beaming

  • available. Same emission

mechanism as in blazars?

  • Possibly see lobe emission

from regions outside of the core.

Wednesday, November 9, 2011

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SLIDE 7
  • Modeling - how do these fit in with the emission

seen from blazars?

  • Are FR1’s the parent population of Blazars?
  • Viewing different types of AGN provide clues

to an overall AGN emission scheme.

  • Complicated Geometries (like spline-sheath)?
  • What’s the location of the

VHE/HE emission?

  • Hadronic vs. Leptonic scenarios?

What are we trying to Learn?

Wednesday, November 9, 2011

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SLIDE 8

NGC 1275

LAT 3-month and 11 month

  • localizations. Evidence for

long-term GeV variability (seen by Cos B, not by EGRET)

VERITAS upper limit combined with LAT measurement not compatible with a power-law.

Acciari et. al. (2009) - lead N. Galante ApJ, 2009, 699 - lead J. Kataoka w/ MOJAVE

Wednesday, November 9, 2011

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SLIDE 9

NGC 1275 Fermi

  • Flaring seen in 2009 along with GeV

hardening (Kataoka et al 2010).

  • Large Flare seen in 2010 along with a VHE

detection by MAGIC (Donato et al. Atel).

  • These flares might correlate

with Radio flares.

  • Important to use radio/GeV to

trigger T eV observations since nothing is usually seen.

2009

2010

LAT > 0.8 GeV

Wednesday, November 9, 2011

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SLIDE 10

Centaurus A

  • Nearest (3.7 MPc) radio

galaxy with giant radio lobes.

  • The LAT ‘sees’ both the

lobes and the core.

  • 10 degree extent in radio.

Credit: Ilana Feain, Tim Cornwell & Ron Ekers (CSIRO/ATNF); ATCA northern middle lobe pointing courtesy R. Morganti (ASTRON); Parkes data courtesy N. Junkes (MPIfR); ATCA & Moon photo: Shaun Amy, CSIRO Wednesday, November 9, 2011

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SLIDE 11

Cen A: LAT detection

Science, 2010, 328 - Lead by Cheung, Fukazawa, Knodlseder and Stawarz

Wednesday, November 9, 2011

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SLIDE 12

Inverse Compton Emission

  • IC (CMB+EBL) origin of LAT emission with B ~ 1 uG (near

equipartition).

  • IC component dominant, Ucmb/UB ~ 10 means that the B-field is low in

the lobes compared to other sources.

  • Should see hard X-ray emission (not seen)

Wednesday, November 9, 2011

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SLIDE 13

EBL Probe

  • Could probe EBL as IC/EBL dominates here at

energies above ~ GeV.

  • Deeper analysis is underway using the full 3 year

dataset.

Wednesday, November 9, 2011

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SLIDE 14

VHE Detection

  • Detection by HESS (long

integration)

  • VHE/HE spectra are barely

consistent.

  • IF FR I’s are the parent

population of blazars than SSC model should work but an SSC cannot explain the VHE emission

  • Different emission regions?

ApJ, 2009 - lead M. Raue and J.-P. Lenain

Wednesday, November 9, 2011

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SLIDE 15

90 cm VLA (NRAO/AUI/NSF) NEED REFERENCES FOR THESE PLOTS!!!!!

Wednesday, November 9, 2011

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SLIDE 16

90 cm VLA (NRAO/AUI/NSF) NEED REFERENCES FOR THESE PLOTS!!!!!

Wednesday, November 9, 2011

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SLIDE 17

90 cm VLA (NRAO/AUI/NSF) 43 GHz VLBA NEED REFERENCES FOR THESE PLOTS!!!!!

Wednesday, November 9, 2011

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SLIDE 18

90 cm VLA (NRAO/AUI/NSF) 43 GHz VLBA NEED REFERENCES FOR THESE PLOTS!!!!!

Wednesday, November 9, 2011

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SLIDE 19

90 cm VLA (NRAO/AUI/NSF) 43 GHz VLBA

Core HST-1 Knot A

NEED REFERENCES FOR THESE PLOTS!!!!!

Wednesday, November 9, 2011

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SLIDE 20

M87: The One and Only

  • Only non-blazar AGN detected by the

previous generation of VHE instruments.

  • What did we learn about it - EGRET?
  • Jet Angle ~ 30 degrees
  • Distance ~ 16 Mpc (no EBL, resolved

structures in radio)

  • Central Black hole: M ~ 3x109 M.

Wednesday, November 9, 2011

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SLIDE 21

LAT Understanding

  • MeV/GeV emission is 1 zone SSC with

moderate jet beaming: d ~ 2-4

  • Does not preclude non-core emission

ApJ, 2009, 707 - lead Cheung, McConville

Wednesday, November 9, 2011

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SLIDE 22
  • 2005 Flare description will be here.

Wednesday, November 9, 2011

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SLIDE 23
  • 2005 T

eV flare (HESS) coincided with X-ray/UV/radio flaring in knot HST

  • 1

(> 120 pc)

Wednesday, November 9, 2011

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SLIDE 24

VHE X-ray Radio HST

  • 1

Core No Core VHE Flare

Wednesday, November 9, 2011

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SLIDE 25

Using VHE lightcurve as a source function Accurately model the 43 GHz radio light curve as synchrotron self absorbed flux Why does the Radio Flux slowly Rise? Inject Electrons into a ‘slow

  • uter sheath’ of jet plasma

Radio-emitting plasma is optically thick at the beginning but then expands and thins

  • ut optically

Wednesday, November 9, 2011

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SLIDE 26
  • 2005 TeV flare (HESS)

coincided with X-ray/UV/ radio flaring in knot HST

  • 1 (> 120 pc)
  • 2008 TeV flare (VERITAS,

MAGIC, HESS) coincided with radio flaring in core (sub-pc)

  • 2010 TeV ~20% Crab

(highest ever) with LAT, VLBA and Chandra Coverage

Wednesday, November 9, 2011

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SLIDE 27

Brightest VHE flare ever seen (~20% Crab) Enough photons to divide spectra into different states

Wednesday, November 9, 2011

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SLIDE 28
  • 2005 TeV flare (HESS)

coincided with X-ray/UV/ radio flaring in knot HST

  • 1 (> 120 pc)
  • 2008 TeV flare (VERITAS,

MAGIC, HESS) coincided with radio flaring in core (sub-pc)

  • 2010 TeV ~20% Crab

(highest ever) with LAT, VLBA and Chandra Coverage

Wednesday, November 9, 2011

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SLIDE 29

Conclusions

  • Highly variable objects need highly

coordinated multiwavelength campaigns.

  • Next generation will see many more of

these - but monitoring + campaigning will still be the key. Use radio and HE to detect high states (keep Fermi going...)

Wednesday, November 9, 2011