Hard X-ray study of lobes of radio galaxy Fornax A

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. Radio Galaxies in the Chandra Era

2. Radio Galaxy Fornax A • Nearby radio galaxy (D = 18.6 Mpc) • The 1st source, from whichthe 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 mG (Isobe et al. 2006) , which is slightly smaller than the field under the minimum energy condition (1.55mG). • 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 Radio Galaxies in the Chandra Era

3. Radio Galaxy Fornax A • Nearby radio galaxy (D = 18.6 Mpc) • The 1st source, from whichthe 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 mG (Isobe et al. 2006) , which is slightly smaller than the field under the minimum energy condition (1.55mG). • 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 GX = 1.62 -0.15 +0.24 (Isobe et al. 2006) Radio Galaxies in the Chandra Era

4. Radio Galaxy Fornax A • Nearby radio galaxy (D = 18.6 Mpc) • The 1st source, from whichthe 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 mG (Isobe et al. 2006) , which is slightly smaller than the field under the minimum energy condition (1.55mG). • 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) Radio Galaxies in the Chandra Era

5. 102 103 104 103 104 105 Lorents factor ge What we have to do next Spectral Energy Distribution (Isobe et al. 2006) • 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. Radio Galaxies in the Chandra Era

6. The X-ray Observatory Suzaku Suzaku • The 5th Japanese X-ray satellite, launched July 10, 2005. (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) • Si-PIN diode : 10 – 60 keV • GSO scintillator : 60 – 300 keV • Wide energy band • low background HXD XIS Radio Galaxies in the Chandra Era

7. HXD/PIN FoV (FWHM) Suzaku observation of Fornax A 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) Radio Galaxies in the Chandra Era

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

9. Wide-band X-ray spectrum of the west lobe PL component G = 1.82 ±0.22 S1keV = 137 -29 +32 nJy 0.2 keV 0.8 keV Radio Galaxies in the Chandra Era

10. ge = 4200 ge = 4200 Spectral Energy Distribution GR= 1.68 ± 0.05 GX= 1.82 ± 0.22 Spectrum of the radio electrons is connected to that of IC X-ray electrons Radio Galaxies in the Chandra Era

11. Physical quantities in lobes West Lobe (Suzaku, This Work ) East Lobe (XMM-Newton, Isobe et al. 2006) R (arcmin) (kpc) S1.4GHz (Jy) GR GX S1keV (nJy) 10 54.1 44 ±5.9 1.68 ± 0.05 1.62 -0.15 +0.24 90 +8 -9 12 64.9 74 ± 7.7 1.68 ± 0.05 1.82 ± 0.22 137 -29 +32 1.55 1.23 ± 0.07 0.61 ± 0.07 3.0 ± 0.3 5.0 ± 1.0 1.59 1.4 ± 0.1 0.78 ± 0.10 2.36 ± 0.25 3.0 ± 0.7 Bme (mG) BIC (mG) uB (10-13 erg cm-3) ue (10-13 erg cm-3) ue/um Radio Galaxies in the Chandra Era

12. 103 104 105 GLAST Sensitivity (5 s / 1year) Cheung et al. 2006 Sambruna @ 1st GLAST Symp. NeXT SXI/HXT Future perspective 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 G = 1.82±0.22 and S1keV = 137-29+34 nJy. • A comparison between the radio and X-ray fluxes gives B = 1.4±0.1 mG, which is slightly smaller than the minimum energy field Bme = 1.59 mG. • The X-ray photons of 20 keV corresponds to the electron Lorents factor of ge～ 5000. As a result, we have succeeded in connecting the electron spectra of synchrotron and IC emitting electrons. Radio Galaxies in the Chandra Era

14. References • Kaneda et al. 1995 ApJ 453, L13 • Iyomoto et al. 1998 ApJ 503, L31 • Tashiro et al. 2001 ApJ 546, L19 • Isobe et al. 2006 ApJ 645, 256 Radio Galaxies in the Chandra Era