Fabrizio Tavecchio - INAF/OA Brera
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Fabrizio Tavecchio Fabrizio Tavecchio - INAF/OA Brera - INAF/OA Brera Probing relativistic particles in jets
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Probing relativistic particles in jets. Fabrizio Tavecchio - INAF/OA Brera. Relativistic particles …. Standard scenario: particle acceleration through Fermi I type mechanism at a shock front (“diffusive shock acceleration”):. - PowerPoint PPT Presentation
Transcript of Fabrizio Tavecchio - INAF/OA Brera
Fabrizio TavecchioFabrizio Tavecchio - INAF/OA Brera - INAF/OA Brera
Probing relativistic particles in jets
Standard scenario:
particle acceleration through Fermi I type mechanism at a shock front (“diffusive shock acceleration”):
N() = No -n n=2 strong, non-relat. shocks; n=2.2 relativistic case
inj >>1 depending upon conditions in the plasma
< max limited by balance acc. rate = cooling rate
Relativistic particles …
Broken-power law distributions expected from continuous injection + cooling
But n2=n1+1 ~3 for blazars we need n2=4-5
n=2 also expected from cooling of high-energy e
… in jets
radiogalaxy, RL QSOsblazar
Urr
y &
Padovan
i 1995
Emission lines
EW>5 Å FSRQ
EW<5 Å BL Lac
Synchro
Radio IR Opt UV X Radio IR Opt UV X MeV GeVMeV GeV
Spectral Energy Distribution and emission mechanisms
Inverse Compton(also possiblehadronic models)
Log
Log N()
n1
n2
b
?
?
inj
CoolingCold particlesTotal number: jet power
max
Acceleration
The electron energy distribution
Foss
ati
et
al. 1
99
8;
Don
ato
et
al. 2
00
1
TheThe “blazar“blazar sequence”sequence”FSRQs
BL Lacs
Simbol - X
But see e.g. Padovani 2007
Log
Log N()
n1
n2
b
Low power blazars: probing the high energy end
The simplest model - SSC
Log
Log N()
n1
n2
b +Log
Log Usyn()
1
’ s
Log
Log L()
2
s
2
C
C =’s b2
L()~T c Usyn N() 2 V 4
Tavecchio et al. 2001
Low power blazars: probing the high energy end
Maraschi et al. 1999
Courtesy PO Petrucci
1999
TeV (Whipple)
X-r
ays
X-r
ays
TeV (Whipple)TeV (Whipple)TeV (Whipple)
X-raysX-rays
2000
Maraschi et al. 1999
Fossati et al., in prep
Mkn 421
Signatures of cooling/acceleration processes are expected.
The best way to detect them is through X-ray monitoring of TeV blazars,
since we can probe the synchrotron emission of the most energetic electrons.
t(hard/soft)~1000 s
If acc. due to shocks:
B~0.6 10-1 G
Soft
Medium
Hard
Ravasi
o e
t al. 2
004
Mkn 421 XMM-Newton Dec. 2002
TeV spectra and intergalactic absorption
Aharonian et al. 2006 using recent HESS data of the BL Lac 1101-232 (z=0.186) found that, even assuming the lowestlevel of the IR background (estimated through galaxy counts), the de-absorbed spectrum is very hard (<1.5).
The broad-band X-rayspectrum is required toconstrain the intrinsic slope
The broad-band X-rayspectrum is required toconstrain the intrinsic slope
High-Energy Observatories 2004-2020High-Energy Observatories 2004-2020
Log
Log N()
n1
n2
b
High power blazars: probing the low energy end
The simplest model - EC
Log
Log N()
n1
n2
b +Log
Log Uext()
’ o
Log
Log F()
2
s
2
C
Broad line region,Disk
C =’ob2
L()~T c Uext N() 2 V 4
’ o = o
High power blazars: probing the low energy end
Pian et al. 2006
ISGRI 20-40 keV A hard X-ray flare of 3C454.3
Variability …
Luigi Foschini’s talk
Extremely hard slopes…
Tavecchio et al. 2007, in press
Extremely hard! n=1.5!
Suzaku
SWIFT/BAT, 9-month survey
Sambruna et al. 2006
Cold matter: X-ray signatures
Celo
tti, G
his
elli
ni &
Fabia
n 2
00
7
Broad band spectra necessary to obtain effective constraints
Conclusions
The (hard) X-ray band is crucial to address several problemsrelated to the origin and dynamics of relativistic particles in jets
Low energy blazars: probe of the high energy end; particleacceleration; help for the estimate of the CIRB
High power: investigation of low energy electrons; variability; cold particles
