Radio galaxyEllipticalFanaroff-Riley type I“Misaligned” BL Lac (~ 60)Distance 3.5 Mpc

Parameter Value

(J2000) 201.3650633

(J2000) -43.0191125

Galaxy Size 18 14 arcmin

Radio Source size 8 4 degrees

Distance 3.5 Mpc

Apparent Magnitude 7.96 mag

Total galaxy mass (41) 1011 M

Outer radio lobe 250 kpc

Inner radio lobe 5 kpc

Inner radio jet 1.35 kpc

Relativistic nuclear jet 1.65 pc

Radio core 0.008 pc

Dust lane radius 7 kpc

Optical image of Centaurus A (ESO/MPG 2.2-m telescope with WFI)

Outer lobes (408MHz) (20o20o, Haslman 1982 )

Outer lobes 6.9cm(4.75GHz) (5o9o, Junkes 1993)

Blue : Radio jetRed : COWhite : Atomic hydrogen gasYellow : shell(32’ 32’, Charmandaris 2000)

30 kpc ~ 0.3

Image size = 15 14 arcmin

RadioVLA(6cm)4.9GHz

Far infraredIRAS60-100m

Mid infraredSpitzer3.6 to 8m

VisibleDSS405-645nm

Near infrared2MASS1.2-2.17m

UltravioletGALEX130-300nm

Gamma

CANGAROO-III Angular resolution

X-rayChandra1-3 keV

0.25o

Oneeventresolution

10% of galaxies AGN

AGN - Time variation (1000sec) - It is 100 or more times brighter than the stars of the whole galaxy. - A massive black hole (MBH) as its nuclei

10% of AGN Jet (Blazar)

Jet - Super luminal motion 　　　　 - Radio lobe - Hot spot　　　　　 - Knot 　　

Unified model of AGN

Cen A 　60°

• Double-peaked structure= synchrotron + inverse Compton(Synchrotron Self-Compton model)

HBL

LBL

1~IC

sync

L

L

ray

Same cut as Crab ( L > 0.9 ) 2 distribution

Integral Flux 2- upper limit

7% Crab FluxOur flux limit is 10 times lower than previous results.

Possibility on HBL assumption

1~/

10~/ 8

sc

sc

LL

1580/1/ sc LL

Typical AGN model

But Cen A…

syncsync

B

sync

sync

ssc

UcRL

U

U

L

L

424

1

2

)12/(250

8/1

/3500580

/6~

2.0~

12

kpcRGB

BU

cceVUU

cceVU

kpcR

B

syncB

sync

IC peak

Synchrotron peak

Rad

io

Infr

ared

/ o p

t ica l X r

ay

Gam

ma

( MeV

) Gam

ma

( Te V

)

Relativistic beaming effect

Bai estimation

CANGAROO-III

Bai, J.M. et al 1999F(0.25-30TeV) = 6.410-9 erg cm-2 s-1 : BaiF(>530GeV) = 2.610-12 erg cm-2 s-1 : CANGAROO-III

The day-by-day results of Cen A observation

We cannot find any sign of bursts.

)/(

1)4/(3

22

MEd

d

M

dVvB

dE

dF

h

CDMqq

2nBv qq

The annihilation rate of the CDM can be written as

MdE

d

h /

1

The accelerator measurement on thefragmentation function

is limited to lower energy of such as 100 MeV. The gamma-ray flux is written

Cen A → 　 Giant Galaxy　　　　　　　 3.5 Mpc

Search for Gamma-rays from the Active radio galaxy Centaurus A with CAN

GAROO-III telescopes

We have observed the giant radio galaxy Centaurus A (Cen A) in the TeV energy region using the CANGAROOIIIstereoscopic system. The system has been in operation since 2004 and is an array of four Imaging Atmospheric

Cherenkov Telescopes (IACT) with about a 100 m spacing. The observations were carried out betweenMarch and April 2004. In total 20-hour data were obtained. No statistically significant gamma-ray signal has

been found above 530 GeV and we obtain an integral flux upper limit of 3.2 10-12 cm-2 sec-1 (2- level).This upper limit is less than 7 % of the gamma-ray flux from the Crab nebula. Although some groups reporteddetections of Cen A in the past, we give upper limits more than one-order of magnitude lower for this object.

S. Kabuki(a), R. Enomoto(b), M. Mori(b) and CANGAROO collaborators (a) Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan

(b) Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan

Radio images of Centaurus A

Multiwavelength images of Centaurus A

Active Galactic Nuclei (AGN)

Synchrotron self-Compton model

Result of Analysis

Estimation of Flux (burst)

Upper limit on density of CDM

In this paper, we showed the result of the first stereoscopic observation ofCen A with CANGAROO-III telescopes. The observation period was from March 16 to April 19 2004 and the total observation time was 1197 min. We could not detect a TeV gamma-ray signal and the 2- upper limit was obtained to be 3.210-12 cm-2 sec-1 at energies greater than 530 GeV. This 2- upper limit corresponds to be approximately 7 %-Crab flux. This is an order of magnitude lower than past results. We derived physical parameters for an HBL model using our upper limits and multi-wavelength spectra. Assuming a volume of the emission region to be that defined by our angular resolution, we obtained a limit on the magneticfield: B > 210 G (R/12 kpc)-1. Even using a size of an order of a light year, it exceeds one Gauss, a situation which can be hardly understood. We conclude that Cen A is not classified as a normal HBL.

Conclusions

Blazar ~ 1/ ~ ~10

cos

Define beaming factor

The flux can be written as Fobs ＝ 2+αF ＝ p F.If we see Mrk501 at 60 degrees inclination like Cen A,with typical values, ~5 and p~3, the flux changes by　 　　 p = 1.3×10-4 .If we assume Mrk501 is at the same distance of Cen A,　 (F Mrk501/F CenA)2 = (z Mrk501/z Cen A)2 = (0.034/0.0008)2 = 1.8104 Thus, even if its inclination is 60 degrees like Cen A, the gamma-ray signal could be detected.

The gamma-ray signal was undetectable. The problem of the inclination of the jet?

H.E.S.S. limit (Aharonian et al, 2005)

.