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Register a new userDeep Chandra X-ray Imaging of a Nearby Radio Galaxy 4C+29.30: X-ray/Radio Connection
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Aneta Siemiginowska
Publication date
2012
fields
Physics
and research's language is
English
Authors
Aneta Siemiginowska
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We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z=0.0647). The Chandra image resolves structures on sub-arcsec to arcsec scales, revealing complex X-ray morphology and detecting the main radio features: the nucleus, a jet, hotspots, and lobes. The nucleus is absorbed (N(H)=3.95 (+0.27/-0.33)x10^23 atoms/cm^2) with an unabsorbed luminosity of L(2-10 keV) ~ (5.08 +/-0.52) 10^43 erg/s characteristic of Type 2 AGN. Regions of soft (<2 keV) X-ray emission that trace the hot interstellar medium (ISM) are correlated with radio structures along the main radio axis indicating a strong relation between the two. The X-ray emission beyond the radio source correlates with the morphology of optical line-emitting regions. We measured the ISM temperature in several regions across the galaxy to be kT ~ 0.5 with slightly higher temperatures (of a few keV) in the center and in the vicinity of the radio hotspots. Assuming these regions were heated by weak shocks driven by the expanding radio source, we estimated the corresponding Mach number of 1.6 in the southern regions. The thermal pressure of the X-ray emitting gas in the outermost regions suggest the hot ISM is slightly under-pressured with respect to the cold optical-line emitting gas and radio-emitting plasma, which both seem to be in a rough pressure equilibrium. We conclude that 4C+29.30 displays a complex view of interactions between the jet-driven radio outflow and host galaxy environment, signaling feedback processes closely associated with the central active nucleus.
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We present results from a study of a nuclear emission of a nearby radio galaxy, 4C+29.30, over a broad 0.5-200 keV X-ray band. This study used new XMM-Newton (~17 ksec) and Chandra (~300 ksec) data, and archival Swift/BAT data from the 58-month catalog. The hard (>2 keV) X-ray spectrum of 4C+29.30 can be decomposed into an intrinsic hard power-law (Gamma ~ 1.56) modified by a cold absorber with an intrinsic column density N_{H,z} ~ 5x10^{23} cm^{-2}, and its reflection (|Omega/2pi| ~ 0.3) from a neutral matter including a narrow iron Kalpha emission line at the rest frame energy ~6.4 keV. The reflected component is less absorbed than the intrinsic one with an upper limit on the absorbing column of N^{refl}_{H,z} < 2.5x10^{22} cm^{-2}. The X-ray spectrum varied between the XMM-Newton and Chandra observations. We show that a scenario invoking variations of the normalization of the power-law is favored over a model with variable intrinsic column density. X-rays in the 0.5-2 keV band are dominated by diffuse emission modeled with a thermal bremsstrahlung component with temperature ~0.7 keV, and contain only a marginal contribution from the scattered power-law component. We hypothesize that 4C+29.30 belongs to a class of `hidden AGN containing a geometrically thick torus. However, unlike the majority of them, 4C+29.30 is radio-loud. Correlations between the scattering fraction and Eddington luminosity ratio, and the one between black hole mass and stellar velocity dispersion, imply that 4C+29.30 hosts a black hole with ~10^8 M_{Sun} mass.
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