tadayuki takahashi institute of space and astronautical science (isas)
DESCRIPTION
Spectral and Temporal Variations of Blazars. Tadayuki Takahashi Institute of Space and Astronautical Science (ISAS). Hidetoshi Kubo(Kyoto), Jun Kataoka (Tokyo IT), Chiharu Tanihata (ISAS). 3C46 (1.4 GHz). Cosmic Ray Spectrum. core (AGN) + inner jet. knot. Yes:AGN. lobe. hot spot. - PowerPoint PPT PresentationTRANSCRIPT
Tadayuki TakahashiInstitute of Space and Astronautical Science (ISAS)
Spectral and Temporal Variations of Blazars
Hidetoshi Kubo(Kyoto), Jun Kataoka (Tokyo IT), Chiharu Tanihata (ISAS)
Cosmic-ray and Particle Accelerator
• Where are accelerators?
• What’s the maximum energy?
• How powerful?• “Black Holes” are
important players?
Blazars are ideal objects tostudy the behavior of particleaccelerators at the bottom of Jets
3C46 (1.4 GHz)
core (AGN) + inner jet
knot
lobe
hot spot
Yes:AGN
Cosmic Ray Spectrum
Gamma-ray Blazars
• Gamma-rays – Direct evidence of the exi
stence of GeV/TeV particles
– the emitting source cannot be
• too compact• too close to important sour
ces of X-ray photon (e.g. a hot accretion disk corona close to the black hole)
to avoid γγ-> e+e-
EGRET sky map of AGNs
TeV detection
Third EGRET AGN Catalogue
Mrk 421
Takahashi et al. 1996,1999Macomb et al. 1995
ASCA
Whipple (TeV)
EGRET
X-Gamma CorrelationsX and γ-rays are cospatial
Takahashi et al. 1999
1995
Fossatti et al. 2003
Gamma-ray Blazarsproduced in relativistic jets pointing close to the line of sight
observerBLK
Enhancement
by Relativistic Beaming(Lobs 〜 L4)BLKcos
Dominated by non-thermal highly variable
broad-band radiation
High PowerSmall Emax
Low PowerHigh EmaxKataoka 2002
Fit to Spectral Energy Distribution(SED) -> Parameters of Acceleratorsbased on the assumption of
–Synchrotron–Inverse Compton
•Sync. Photon (and External)•Peak frequency relations•Lumunosity relations
Solve “Parent” electron distributionfrom the spectra
• Self-consistent analysis can constrain– Size– Magnetic Field– Beaming Factor– Electron Distribution
(Kinetic Power)
X-ray band is sensitive to γmax and γmin
max = 105
5x105
min = 1 min = 1000
X-ray
Temporal Variations (TeV Blazars)at the maximum end of electron distribution
Takahashi et al. 1999
time (x 10,000 s)
cnts/s
1day
2000
2000
ASCA’s Long-look Observation (Still Difficult for XMM/Chandra)Daily FlareShape : almost symmetric : Light Crossing Effect in the blob
(not the effect of cooling/acceleration time constant)Offset Component (pedestal)
Spectral Variations (TeV Blazars)at the maximum end of electron distribution
Kataoka et al. 2001
Tanihata et al. 2003
Takahashi et al. 2000
Acceleration/Cooling
High if
shock velocity (vs) is high
or is high
€
∝B
€
∝1
B2γ
€
τ acc = τ coolτcool (Obs. Frame)B=0.1 Gauss= 10 0.5 keV … 17,000 s 5 keV … 5,000 s
(at X-rays)
Flare light curve is symmetric.No energy dependence foundin rise/decay.
Time dependent treatment• Time dependent modeling is important to study th
e spectral evolution (but available only very recently)– time scale of
• Acceleration and Cooling• Escape
(Kirk et al. 1999, Kataoka et al. 2000, Krawczynski et al. 2002)
• Predicts characteristic spectral evolution (such as “soft lag/hard lag”) , from the balance between τacc and τcool.
New Component (ex. with higher γmax)
Kataoka 2000
B=0.1 gauss
R=1016 cm3
…
Flare Light Curve
Injection
escape
Solve
the time evolution of electrons
tvar
Characteristic Time Scale
1 day
Mrk421
Mrk501
PKS2155-304
-Daily flares are commonly observed -Characteristic time scale : tvar 〜 40ks - 100ks
-
-Both-Structure Function-PSD
analysis indicate
time variablity <tvar is greatly suppressed for t < tvar
R 〜 ctvar 〜 1016 [cm]
Internal Shocks
€
R ~ ctvarΓ
tvar ~R
cΓ~D
cΓ 2
(R ~ Dsinθ ~ Dθ ~D
Γ)
€
tcatchup ~ 2Γ 2τ
D ~ 2cτΓ 2
€
tvar ~ τ
0.5 - 1 day variabilityroughly corresponds to 10 Rg for 109 M
(Rees 1978Ghisellini 1999, Spada et al. 2001Kataoka et al. 2001)D ~ BLK
2 D0 ~ 1017 [cm]
R ~ BLK D0
~ 1016 [cm]
d ~ 2D0
B.H.
shock
BLK
τ
(Kataoka et al. 2001,Iwashimizu et al. 2003)
Fast shell catches up the slow shell
Link to the Characteristic time scale of the ejection from BH.
Variablity
Light Curve Simulation
- Blobs mainly collide at D ~ 103-4 D0 = 1017-20 [cm]
- m = 10, D0 = 3×1013 [cm]
- Only the flares due to collisions at the smallest distance will be appeared as “shots (daily flares)”
Day-by-dayflares
Internal Energy
Flare time-scale (ksec)
No. of flaresoffset
log D (cm)
Time
Flarge
OFFSETsmaller
structure function
offset component
Tanihata et al. 2003
Simulation Observation
EUVE1keV6.3keV15keV
Rfo =0.7, Tchr =40 ks ⇒ D 0 =1x1013 cm
G =0.015, =15 (assumed) -> very narrow distribution is required
Light Curve (Flare, Energy dependent Amplitudes, SF/PSD are OK. Efficiency <0.01 %
Application to Mrk 421
Similar Analysisby Guetta et al. 2002provides Efficiency < several %still small
avrg
assumption
Energy carried out by the form of Jetdoes not go into electron acceleration/radiation
One more issue to tackle with
Absorption effect (TeV γ)by Diffuse Extragalactic Background Radiation
F. Aharonian 2003
Need to correct TeV spectra for the SED fitting, if the emission exceeds several TeV
Re-visiting SED AnalysisD
B.H.
shockshock
Takahara et al. (Poster 81)
1. IR absorption corrected for TeV spectra (important)
2. Fit quiescent phase to determine parameters. Use higher for flare, scale other parameters with
3. Collision takes place at longer distance for larger
4. maximum energy is higher for larger
Quiescenceδ=12, B=0.12G
δ=37, B=0.012GFlare in 2000
for Mrk 421Flare
Change of the parameters ofaccelerator ?
Another approach to fit FLARE
Paradigm Shift
Inhomogenious Model
(continuous flow)
Before CGRO/TeV/ASCA
Homogenious One Zone Model
After X-GammaCorrelation
Time-DependentOne Zone Model
After Detections ofFlare & Spectral Evolution
Time Dependent(Internal Shocks)
Multi Zone?
After CharacteristicTime Scale (Daily Flare)
Future Observations
ISAS
GLAST2006
AstroE2 GLAST
Kataoka et al. 1999
GLAST SKY
?
poster by Fukazawa et al.
Conclusion• We have a fairly good understanding of Blazar Spectra
(Parameters of Accelerators); ue>uB
• X-ray/TeV correlations give strong constraint on the model
• Low Efficiency in sub-pc jets (Blazar emission)– Most of the energy carried out from BH is transported to kpc-j
ets and Lobes (See Poster 32 by Kataoka)• Shift of Paradigm
Time Dependent Model is indispensable Internal Shock Model (Multi Zone?)
• Need sensible and Detector in hard-X and Gamma
Narrow FOV Compton Telescope for the NeXT mission in Japan
–Stack Configuration•Low Energy 24 layers of Strip Strip detectors (res. 400μm) and 6 mm thick CdTe Pixel (res. 1mm)
–High Energy Resolution of <1 - 3 keV
BGO
•Incident angle of γ-rays are defined by a well-type active collimator (Extremely Low Background)
ISAS