SUZAKU OBSERVATION OF THE GIANT RADIO GALAXY 3C 326

Journal Article · Fri Nov 20 04:00:00 EST 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/706/1/454· OSTI ID:21378201

Isobe, Naoki ^[1]; Tashiro, Makoto S; Seta, Hiromi ^[2]; Gandhi, Poshak; Hayato, Asami ^[3]; Nagai, Hiroshi ^[4]; Hada, Kazuhiro ^[5]; Matsuta, Keiko ^[6]

---

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. Cosmic Radiation Laboratory, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan)
4. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
5. Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
6. Graduate University for Advanced Studies (SOKENDAI), 3-1-1 Yoshinodai, Sagamihara, Kanagawa, 229-8510 (Japan)

A Suzaku observation of a giant radio galaxy, 3C 326, which has a physical size of about 2 Mpc, was conducted on 2008 January 19-21. In addition to several X-ray sources, diffuse emission was significantly detected and associated with its west lobe, but the east lobe was contaminated by an unidentified X-ray source WARP J1552.4+2007. After careful evaluation of the X-ray and non-X-ray background, the 0.4-7 keV X-ray spectrum of the west lobe is described by a power-law model modified with the Galactic absorption. The photon index and 1 keV flux density were derived as GAMMA = 1.82{sup +0.26}{sub -0.24} +- 0.04 and S {sub X} = 19.4{sup +3.3}{sub -3.2} +- 3.0 nJy, respectively, where the first and second errors represent the statistical and systematic ones. The diffuse X-rays were attributed to be inverse Compton (IC) radiation by the synchrotron radio electrons scattering off the cosmic microwave background photons. This radio galaxy is the largest among those with lobes detected through IC X-ray emission. A comparison of the radio to X-ray fluxes yields the energy densities of electron and magnetic field as u{sub e} = (2.3 +- 0.3 +- 0.3) x 10{sup -13} erg cm{sup -3} and u{sub m} = (1.2{sup +0.2}{sub -0.1} +- 0.2) x 10{sup -14} erg cm{sup -3}, respectively. The galaxy is suggested to host a low-luminosity nucleus with an absorption-corrected 2-10 keV luminosity of <2 x 10{sup 42} erg s{sup -1}, together with a relatively weak radio core. The energetics in the west lobe of 3C 326 were compared with those of moderate radio galaxies with a size of approx100 kpc. The west lobe of 3C 326 is confirmed to agree with the correlations for the moderate radio galaxies, u{sub e} propor to D {sup -2.2+}-{sup 0.4} and u{sub m} propor to D {sup -2.4+}-{sup 0.4}, where D is their total physical size. This implies that the lobes of 3C 326 are still being energized by the jet, despite the current weakness of the nuclear activity.

• OSTI ID: 21378201
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 706; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
BOSONS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
ENERGY DENSITY
ENERGY RANGE
FERMIONS
FLUX DENSITY
GALAXIES
IONIZING RADIATIONS
KEV RANGE
KEV RANGE 01-10
LEPTONS
LUMINOSITY
MAGNETIC FIELDS
MASSLESS PARTICLES
MICROWAVE RADIATION
OPTICAL PROPERTIES
PHOTONS
PHYSICAL PROPERTIES
RADIATION SOURCES
RADIATIONS
RADIO GALAXIES
RELICT RADIATION
SORPTION
SPECTRA
X RADIATION
X-RAY GALAXIES
X-RAY SOURCES
X-RAY SPECTRA