The Fermi blazars divide

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The Fermi blazars divide
Gabriele Ghisellini Osservatorio Astronomico di
Brera In collaboration with L. Maraschi and F.
Tavecchio
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Bright Fermi blazars

• gt100 with gt10s detection
• 57 FSRQs and 42 BL Lacs
• Redshift for all FSRQs and for 30 BL Lacs

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FSRQs
TeV
g-ray energy spectral index ag
There is a sequence
Ghisellini, Maraschi, Tavecchio 2009
BL Lacs
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despite dramatic variability
Ghisellini, Maraschi, Tavecchio 2009
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BL Lac
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Fermi
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454.3
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Agile
Fermi
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0528
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Fermi
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279
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MAGIC
Fermi
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The blazar sequence
FSRQs
Steep
Lg
Fossati et al. 1998 Donato et al. 2001
BL Lacs
Flat
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Steep FSRQs
Flat BL Lacs
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The divide
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The blazar divide
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Celotti GG 2008
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Celotti GG 2008, Maraschi 2008
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GG, Tavecchio Ghirlanda in prep,
Celotti GG 2008, Maraschi 2008
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Ledlow Owen
Ghisellini Celotti 2000
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Ghisellini Celotti 2000
Ledlow Owen
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Jet power vs disk Lum.
BL Lacs, FSRQ FRI, FRII
Photon trapping
Pjet
Ldisk Pjet
e-p decoupling
Ldisk
10-2
Disk accretion rate (Eddington units)
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Mgt0.01MEdd
MeV
Far IR
Torus 1-10 pc
BLR
Standard disk
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Mlt0.01MEdd
TeV
X
TeV
BLR ltlt0.2 pc
ADAF disk
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Evolution? (e.g. Cavaliere DElia 2002)

• M should increase with redshift
• In the past more FSRQs (and FRII) positive
  evolution?
• Now more BL Lacs (and FRI) negative evolution?
• And taken together? Similar to radio-quiet or
  not?

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Conclusions/Predictions

• The most powerful Fermi blazars should be
  accreting near Eddington, and have the largest
  black hole masses
• Also radio-quiet should have much weaker broad
  lines for Mlt0.01MEdd
• As the survey goes on, including weaker sources.

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smaller M
0948
forbidden except extraordinary and rare states
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Conclusions/Predictions

• The most powerful Fermi blazars should be
  accreting near Eddington, and have the largest
  black hole masses
• Also radio-quiet should have much weaker broad
  lines for Mlt0.01MEdd

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From Ho, 2008, ARAA.. For radio-quiet 8. Low
luminosity AGNs are not simply scaled-down
versions of powerful AGNs. Their central engines
undergo fundamental changes when the accretion
rate ltlt Eddington. In this regime, the BLR and
obscuring torus disappear 9. Below L0.01
Eddington, the canonical accretion disk
transforms into an inner vertically thick and
radiatively inefficient accretion flow.
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M
Ljet propto Ldisk
M2
1/2
Ljet propto Ldisk
ADAF (Narayan et al.)
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By modeling, we find physical parameters in the
comoving frame. gpeak is the energy of electrons
emitting at the peak of the SED
EGRET blazars
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Low power slow cooling large gpeak
Big power fast cooling small gpeak
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tcool 1/(gpeak U) R/c
µ
2
g gpeakU const
µ
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Power of jets
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The power of blazar jets
G
Lr radiation
Le relat. electrons
Lp protons
LB B-field
R
1017 cm
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High power
If one p per e-
Relat. electrons
Celotti Ghisellini 2007
Powerful jets are not magnetically dominated
Magnetic Field
Radiation
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Low power
If one p per e-
Relat. electrons
Celotti Ghisellini 2007
Magnetic Field
Radiation
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