Decelerating Flows in TeV Blazars

1
Decelerating Flows in TeV Blazars

• Markos Georganopoulos
• Demosthenes Kazanas
• NASA/GSFC

2
Homogeneous TeV blazar models require high
Doppler boosting ( d50). Why?

• Because this is the only solution to the
  
• problem of the missing seed photons

Comoving frame ec 1/eb
Observers frame ec,obs d ec eb,obsd eb
d2 ec,obs eb,obs d 15 (E?ev ?16)1/2
eb
??? (?L? )
Coolingescape
??? (?)
3
Homogeneous TeV blazar models require high
Doppler boosting ( d50). Why?

• Because this is the only solution to the
  
• problem of the missing seed photons

Comoving frame ec 1/eb
Observers frame ec,obs d ec eb,obsd eb
d2 ec,obs eb,obs d 15 (E?ev ?16)1/2
eb
1 TeV
??? (?L? )
Coolingescape
Tavecchio et al 01
??? (?)
4
Homogeneous TeV blazar models require high
Doppler boosting ( d50). Why?

• Because this is the only solution to the
  
• problem of the missing seed photons

Comoving frame ec 1/eb
Observers frame ec,obs d ec eb,obsd eb
d2 ec,obs eb,obs d 15 (E?ev ?16)1/2
??? (?L? )
de Jager Stecker 02
??? (?)
5
Homogeneous TeV blazar models require high
Doppler boosting ( d50). Why?

• Because this is the only solution to the
  
• problem of the missing seed photons

Comoving frame ec 1/eb
Observers frame ec,obs d ec eb,obsd eb
d2 ec,obs eb,obs d 45 (E10Tev ?16)1/2
??? (?L? )
de Jager Stecker 02
??? (?)
6
Problems with high values of d
FR I - BL Lac Unification ( Urry Padovani 95)
G? 4, ?crit ? 15?
?jet?1/G
For dG50, ?obs1/G?1? Very well
aligned!!! Greatly over-estimates the parent
population of FR I sources.
?jet ?crit 15? gtgt 1/G

• Injected power increase LinjLobs ?2crit G2 ?
  200 Lobs 2 1046 erg/s
• This is typical of powerful blazars and FR IIs,
• NOT of FR Is and BL Lacs

7
Even Lorentz factors as low as ??15 fail to
reproduce the parent population of FR Is.

• Chiaberge et al. 00

Proposed solution (Chiaberge et al. 00) Velocity
structure in the jet fast spine, slow outer
layer. The fast spine dominates in BLs, the
slower outer layer in FR Is.
8
No fast spine is detected in Space VLBI
observations of MKN 421 MKN 501
Piner et al. 99 Edwards Piner 02
ßapp?0.6 c Sub-luminal speeds!

• Marscher 99 The flow must decelerate from the
  high
• energy to the radio emitting
  region.

9
Not only the two MKN, but a good fraction of BL
Lacs have small ßapp

• Jorstad et al. 01

10
Radiation beaming patterns for a relativistic and
decelerating flow.
Fast, relativistic flow, more energetic
electrons
Slower flow, lower energy electrons
11
Radiation beaming patterns for a relativistic and
decelerating flow.
Fast, relativistic flow, more energetic
electrons
Slower flow, lower energy electrons
Strongly beamed Synchrotron and SSC emission from
the fast part of the flow. Dominates the high
energy part of the observed synchrotron spectrum
in BL Lacs. The SSC emission contributes to the
observed GeV-TeV emission.
12
Radiation beaming patterns for a relativistic and
decelerating flow.
Fast, relativistic flow, more energetic
electrons
Slower flow, lower energy electrons
Less beamed radio synchrotron and SSC emission
from the slow part of the flow. Dominates the
radio and X-ray output in FR Is.
13
Upstream Compton (UC) Scattering.
Higher seed photon energy density Tighter beaming
pattern
?1 ?2
U U2G2rel
Synchrotron and SSC from each zone
L1 ? ?12a, L2 ? ?22a UC LUC?
?132a / ?21a
14
Radiation beaming patterns for a relativistic and
decelerating flow.
Fast, relativistic flow, more energetic
electrons
Slower flow, lower energy electrons
UC emission Synchrotron seed photons from the
slow part of the flow are scattered by the
upstream energetic electrons of the fast part of
the flow. UC is the major
contributor to the TeV flux.
15
Emission from a decelerating relativistic flow

• Flow decelerates from G15 to G4,
• R1016 cm
• ?max107, B0.1 G
• ?13?, ?26?

16
Emission from a decelerating relativistic flow
The more a flow decelerates, the higher the UC
peak energy and power.
17
BL Lac FR I Unification

• Trussoni et al. 03
• (LBL/LFRI)R?102.5
• (LBL/LFRI)O?103.9
• (LBL/LFRI)X?103.5

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1. The current situation

• In single velocity models, a 10 TeV peak energy
  requires high (d 45) Doppler factors to ease
  the problem of the missing seed photons.
• Such high Doppler factors are in strong conflict
  with FR Is being the parent population of BLs.
• The sub-luminal speeds observed in several BLs,
  argue for a decelerating flow in these sources.

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2. In a relativistic and decelerating flow

• Upstream Compton (UC) scattering solves the
  missing seed photon problem the upstream
  energetic electrons see the downstream
  synchrotron seed photon energy density boosted.
• High peak energies E 10 TeV, can be
  accommodated with smaller Lorentz factors
  (G?10-15).
• Such a scenario is in agreement with FR Is being
  the parent population of BL Lac objects.