SUZAKU DIAGNOSTICS OF THE ENERGETICS IN THE LOBES OF THE GIANT RADIO GALAXY 3C 35

Journal Article · Tue Feb 01 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/727/2/82· OSTI ID:21567557

Isobe, Naoki ^[1]; Seta, Hiromi; Tashiro, Makoto S ^[2]; Gandhi, Poshak ^[3]

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1. Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
2. Department of Physics, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan)
3. Department of High Energy Astrophysics, ISAS/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 229-8510 (Japan)

The Suzaku observation of a giant radio galaxy 3C 35 revealed faint extended X-ray emission, associated with its radio lobes and/or host galaxy. After careful subtraction of the X-ray and non-X-ray background and contaminating X-ray sources, the X-ray spectrum of the faint emission was reproduced by a sum of the power-law (PL) and soft thermal components. The soft component was attributed to the thermal plasma emission from the host galaxy. The photon index of the PL component, {Gamma} = 1.35{sup +0.56}{sub -0.86}{sup +0.11}{sub -0.10}, where the first and second errors represent the statistical and systematic ones, was found to agree with the synchrotron radio index from the lobes, {Gamma}{sub R} = 1.7. Thus, the PL component was attributed to the inverse Compton (IC) X-rays from the synchrotron electrons in the lobes. The X-ray flux density at 1 keV was derived as 13.6 {+-} 5.4{sup +4.0}{sub -3.6} nJy with the photon index fixed at the radio value. The X-ray surface brightness from these lobes ({approx}0.2 nJy arcmin{sup -2}) is lowest among the lobes studied through the IC X-ray emission. In combination with the synchrotron radio flux density, 7.5 {+-} 0.2 Jy at 327.4 MHz, the electron energy density spatially averaged over the lobes was evaluated to be the lowest among those radio galaxies, as u{sub e} = (5.8 {+-} 2.3{sup +1.9}{sub -1.7}) x 10{sup -14} erg cm{sup -3} over the electron Lorentz factor of 10{sup 3}-10{sup 5}. The magnetic energy density was calculated as u{sub m} = (3.1{sup +2.5}{sub -1.0}{sup +1.4}{sub -0.9}) x 10{sup -14} erg cm{sup -3}, corresponding to the magnetic field strength of 0.88{sup +0.31}{sub -0.16}{sup +0.19}{sub -0.14} {mu}G. These results suggest that the energetics in the 3C 35 lobes are nearly consistent with equipartition between the electrons and magnetic fields.

• OSTI ID: 21567557
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 727; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
EMISSION
FLUX DENSITY
GALAXIES
IONIZING RADIATIONS
MAGNETIC FIELDS
RADIATIONS
RADIO GALAXIES
SPECTRA
X RADIATION
X-RAY SPECTRA