July 7-11, 2008 Radio Galaxies in the Chandra Era 1 Hard X-ray study of lobes of radio galaxy Fornax A Naoki Isobe (RIKEN/Suzaku Help Desk) Makoto Tashiro, Hiromi Seta, Yuichi Yaji (Saitama Univ.) Keiko Matsuta, Hidehiro Kaneda (ISAS/JAXA), Kazuo Makishima (RIKEN/Univ.of Tokyo) etc.

July 7-11, 2008 Radio Galaxies in the Chandra Era 2 Radio Galaxy Fornax A  Nearby radio galaxy (D = 18.6 Mpc)  The 1 st source, from which the lobe IC X-ray emission was detected with ASCA and ROSAT (e.g., Kaneda et al. 1995)  The flux of IC X-ray emission indicate a magnetic field of 1.2 G (Isobe et al. 2006), which is slightly smaller than the field under the minimum energy condition (1.55G).  The X-ray/radio distribution suggest a homogeneous electron and edge- strengthened magnetic field distributions (Tashiro et al. 2001). Color : ASCA (2-10 keV) Contour : VLA 1.4 GHz

July 7-11, 2008 Radio Galaxies in the Chandra Era 3 Radio Galaxy Fornax A  Nearby radio galaxy (D = 18.6 Mpc)  The 1 st source, from which the lobe IC X-ray emission was detected with ASCA and ROSAT (e.g., Kaneda et al. 1995)  The flux of IC X-ray emission indicate a magnetic field of 1.2 G (Isobe et al. 2006), which is slightly smaller than the field under the minimum energy condition (1.55G).  The X-ray/radio distribution suggest a homogeneous electron and edge- strengthened magnetic field distributions (Tashiro et al. 2001). XMM-Newton Spectrum of Fornax A east lobe  X = (Isobe et al. 2006)

July 7-11, 2008 Radio Galaxies in the Chandra Era 4 Radio Galaxy Fornax A  Nearby radio galaxy (D = 18.6 Mpc)  The 1 st source, from which the lobe IC X-ray emission was detected with ASCA and ROSAT (e.g., Kaneda et al. 1995)  The flux of IC X-ray emission from the east lobe indicate a magnetic field of 1.2 G (Isobe et al. 2006), which is slightly smaller than the field under the minimum energy condition (1.55G).  The X-ray/radio distribution suggest a homogeneous electron and edge- strengthened magnetic field distributions (Tashiro et al. 2001). ASCA (2-10 keV) VLA 1.4 GHz (Tashiro et al. 2001)

July 7-11, 2008 Radio Galaxies in the Chandra Era 5 What we have to do next  The Lorents factor of radio electrons is larger than that of X-ray ones  It is important to detect radio/X-ray emission from electrons with the same Lorentz factor.  2 options low-frequency radio Hard X-ray  Low-frequency radio observation is difficult.  Hard X-ray observation with Suzaku is the ideal tool. Spectral Energy Distribution (Isobe et al. 2006) Lorents factor  e

July 7-11, 2008 Radio Galaxies in the Chandra Era 6 The X-ray Observatory Suzaku  The 5 th Japanese X-ray satellite, launched July 10, (about 3 years old.)  2 X-ray detectors XIS (X-ray Imaging Spectrometer) 3 CCD cameras active 1 BI CCD (XIS1) 2 FI CCD (XIS0, 3) 0.2 – 10 keV Low background Good energy resolution HXD (Hard X-ray Detector) PIN Si-PIN diode : 10 – 60 keV GSO GSO scintillator : 60 – 300 keV Wide energy band low background HXDXIS Suzaku

July 7-11, 2008 Radio Galaxies in the Chandra Era 7 Suzaku observation of Fornax A HXD/PIN FoV (FWHM) XIS 0.5 – 10 keV VLA 1.4 GHz (Fomalont et l 1989) 2 Suzaku exposures : Host Galaxy (40 ks) and West Lobe (80 ks)

July 7-11, 2008 Radio Galaxies in the Chandra Era 8 Suzaku HXD/PIN Spectrum Comparison with Data & NXB Hard X-ray signals from the west lobe are significant up to 20 keV. NXB-Subtracted Comparison with Data & CXB CXB (Boldt 1987) Data NXB (Tuned) NXB-Subtracted 2% of NXB

July 7-11, 2008 Radio Galaxies in the Chandra Era 9 Wide-band X-ray spectrum of the west lobe 0.2 keV0.8 keV PL component  = 1.82 ±0.22 S 1keV = nJy

July 7-11, 2008 Radio Galaxies in the Chandra Era 10 Spectral Energy Distribution  e = 4200  R = 1.68 ± 0.05  X = 1.82 ± 0.22  e = 4200 Spectrum of the radio electrons is connected to that of IC X-ray electrons

July 7-11, 2008 Radio Galaxies in the Chandra Era 11 Physical quantities in lobes R (arcmin) (kpc) S 1.4GHz (Jy)  R  X S 1keV (nJy) ± ± East Lobe (XMM-Newton, Isobe et al. 2006) West Lobe (Suzaku, This Work ) ± ± ± B me (G) B IC (G) u B ( erg cm -3 ) u e ( erg cm -3 ) u e /u m ± ± ± ± ± ± ± ± 0.7

July 7-11, 2008 Radio Galaxies in the Chandra Era 12 Future perspective GLAST Sensitivity (5 s / 1year) Cheung et al st GLAST Symp. NeXT SXI/HXT

July 7-11, 2008 Radio Galaxies in the Chandra Era 13 Summary  IC X-ray emission was detected up to 20 keV from the west lobe of Fornax A, with Suzaku HXD.  The X-ray spectrum of the west lobe is described with a PL model with  = 1.82±0.22 and S 1keV = nJy.  A comparison between the radio and X-ray fluxes gives B = 1.4±0.1 G, which is slightly smaller than the minimum energy field B me = 1.59 G.  The X-ray photons of 20 keV corresponds to the electron Lorents factor of  e ～ As a result, we have succeeded in connecting the electron spectra of synchrotron and IC emitting electrons.

July 7-11, 2008 Radio Galaxies in the Chandra Era 14 References  Kaneda et al ApJ 453, L13  Iyomoto et al ApJ 503, L31  Tashiro et al ApJ 546, L19  Isobe et al ApJ 645, 256