Tadayuki Takahashi Institute 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 to study the behavior of particle accelerators 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 existence of GeV/TeV particles –the emitting source cannot be too compact too close to important sources 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. 1996,1999 Macomb et al ASCA Whipple (TeV) EGRET X-Gamma Correlations X and γ-rays are cospatial Takahashi et al Fossatti et al. 2003

Gamma-ray Blazars produced in relativistic jets pointing close to the line of sight observer  BLK  Enhancement by Relativistic Beaming (L obs 〜 L  4 )  BLK  cos  Dominated by non-thermal highly variable broad-band radiation High Power Small Emax Low Power High Emax Kataoka 2002 Fit to Spectral Energy Distribution (SED) -> Parameters of Accelerators b ased on the assumption of –Synchrotron –Inverse Compton Sync. Photon (and External) Peak frequency relations Lumunosity relations

Solve “ Parent ” electron distribution from 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 = x10 5  min = 1  min = 1000 X-ray

Temporal Variations (TeV Blazars) at the maximum end of electron distribution Takahashi et al time (x 10,000 s) cnts/s 1day 2000 ASCA ’ s Long-look Observation (Still Difficult for XMM/Chandra) Daily Flare Shape : 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 Tanihata et al Takahashi et al. 2000

Acceleration/Cooling High if shock velocity ( v s) is high or  is high  cool (Obs. Frame) B=0.1 Gauss  = keV … 17,000 s 5 keV … 5,000 s (at X-rays) Flare light curve is symmetric. No energy dependence found in rise/decay.

Time dependent treatment Time dependent modeling is important to study the 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  acc and  cool. New Component (ex. with higher γmax) Kataoka 2000 B=0.1 gauss R=10 16 cm 3 … Flare Light Curve Injection escape Solve the time evolution of electrons

t var Characteristic Time Scale 1 day Mrk421 Mrk501 PKS Daily flares are commonly observed -Characteristic time scale : t var 〜 40ks - 100ks - -Both -Structure Function -PSD analysis indicate time variablity <tvar is greatly suppressed for t < t var R 〜 ct var  〜 [cm]

Internal Shocks day variability roughly corresponds to 10 Rg for 10 9 M (Rees 1978 Ghisellini 1999, Spada et al Kataoka et al. 2001) D ~  BLK 2 D 0 ～ [cm] R ~  BLK D 0 ~ [cm] d ~ 2D 0 B.H. shock    BLK  (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 ~ D 0 = [cm] -  ｍ = 10,    D 0 = 3×10 13 [cm] - Only the flares due to collisions at the smallest distance will be appeared as “shots (daily flares)” Day-by-day flares Internal Energy Flare time-scale (ksec) No. of flares offset log D (cm) Time F large  OFFSET smaller  structure function offset component Tanihata et al. 2003

Simulation Observation EUVE 1keV 6.3keV 15keV R fo =0.7, T chr =40 ks ⇒ D 0 =1x10 13 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 Analysis by Guetta et al provides Efficiency < several % still small assumption Energy carried out by the form of Jet does 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 Analysis D B.H. shock 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  Quiescence δ=12, B=0.12G δ=37, B=0.012G Flare in 2000 for Mrk 421 Flare Change of the parameters of accelerator ? Another approach to fit FLARE

Paradigm Shift Inhomogenious Model (continuous flow) Before CGRO/TeV/ASCA Homogenious One Zone Model After X-Gamma Correlation Time-Dependent One Zone Model After Detections of Flare & Spectral Evolution Time Dependent (Internal Shocks) Multi Zone? After Characteristic Time Scale (Daily Flare)

Future Observations ISAS GLAST 2006 AstroE2 GLAST Kataoka et al GLAST SKY ? poster by Fukazawa et al.

Conclusion We have a fairly good understanding of Blazar Spectra (Parameters of Accelerators); u e >u B 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- jets 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