Browsing by Author "Evans, D.A."

Now showing items 21-31 of 31

    • A Radio through X-Ray Study of the Jet/Companion-Galaxy Interaction in 3C 321 

      Evans, D.A.; Fong, W-F.; Hardcastle, M.J.; Kraft, R.P.; Lee, J.C.; Worrall, D.M.; Birkinshaw, M.; Croston, J.H.; Muxlow, T.W.B. (2008)

    • Shocks, seyferts, and the supernova remnant connection : A chandra observation of the circinus galaxy 

      Mingo, B.; Hardcastle, M.J.; Croston, J.H.; Evans, D.A.; Kraft, R.P.; Kharb, P.; Lenc, E. (2012-10-20)
      We analyze new Chandra observations of the nearest (D = 4 Mpc) Seyfert 2 active galaxy, Circinus, and match them to pre-existing radio, infrared, and optical data to study the kpc-scale emission. The proximity of Circinus ...

    • Spectral properties of X-ray binaries in Centaurus A 

      Burke, M.J.; Raychaudhury, S.; Kraft, R.P.; Forman, W.R.; Jones, C.; Murray, S.S.; Birkinshaw, M.; Evans, D.A.; Jordán, A.; Worrall, D.M.; Maccarone, T. J.; Croston, J.H.; Brassington, Nicola; Hardcastle, M.J.; Goodger, J.L.; Kainulainen, J.; Woodley, K.A.; Sivakoff, G.R.; Gilfanov, M.; Zhang, Z.; Sarazin, C.L.; Voss, R. (2013-04-01)
      We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states ...

    • The sudden death of the nearest quasar 

      Schawinski, K.; Virani, S.; Urry, C.M.; Natarajan, P.; Coppi, P.; Evans, D.A.; Keel, W.C.; Manning, A.; Lintott, C.J.; Kaviraj, S.; Bamford, S.P.; Józsa, G.I.G.; Garrett, M.; Van Arkel, H.; Gay, P.; Fortson, L. (2010-11-20)
      Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition ...

    • The Suzaku view of the disk-jet connection in the low-excitation radio galaxy NGC 6251 

      Evans, D.A.; Kraft, R.P.; Lee, J.C.; Summers, A.C.; Hardcastle, M.J.; Gandhi, P.; Croston, J.H. (2011-11)
      We present results from an 87 ks Suzaku observation of the canonical low-excitation radio galaxy (LERG) NGC6251. We have previously suggested that LERGs violate conventional active galactic nucleus unification schemes: ...

    • A Transient Black-Hole Low-Mass X-Ray Binary Candidate in Centaurus A 

      Sivakoff, G.R.; Kraft, R.P.; Jordan, A.; Juett, A.M.; Evans, D.A.; Forman, W.R.; Hardcastle, M.J.; Sarazin, C.L.; Birkinshaw, M.; Brassington, Nicola; Croston, J.H.; Harris, W.F.; Jones, C.; Murray, S.S.; Raychaudhury, S.; Woodley, K.A.; Worrall, D.M. (2008)
      We report the discovery of a bright transient X-ray source, CXOU J132518.2–430304, toward Centaurus A (Cen A) using six new Chandra X-Ray Observatory observations in 2007 March-May. Between 2003 and 2007, its flux has ...

    • A transient sub-Eddington black hole X-ray binary candidate in the dust lanes of Centaurus A 

      Burke, M.J.; Raychaudhury, S.; Kraft, R.P.; Forman, W.R.; Jones, C.; Murray, S.S.; Evans, D.A.; Jordán, A.; Brassington, Nicola; Hardcastle, M.J.; Goodger, J.L.; Sivakoff, G.R.; Woodley, K.A.; Kainulainen, J.; Birkinshaw, M.; Worrall, D.M.; Croston, J.H.; Gilfanov, M.; Zhang, Z.; Sarazin, C.L.; Voss, R. (2012-04-20)
      We report the discovery of a bright X-ray transient CXOU J132527.6-430023 in the nearby early-type galaxy NGC5128. The source was first detected over the course of five Chandra observations in 2007, reaching an unabsorbed ...

    • Where Centaurus A gets its X-ray knottiness 

      Worrall, D.M.; Birkinshaw, M.; Kraft, R.P.; Sivakoff, G.R.; Jordan, A.; Hardcastle, M.J.; Brassington, Nicola; Croston, J.H.; Evans, D.A.; Forman, W.R.; Harris, W.E.; Jones, C.; Juett, A.M.; Murray, S.S.; Nulsen, P.E.J.; Raychaudhury, S.; Sarazin, C.L.; Woodley, K.A. (2008)
      We report an X-ray spectral study of the transverse structure of the Centaurus A jet using new data from the Chandra Cen A Very Large Project. We find that the spectrum steepens with increasing distance from the jet axis, ...

    • X-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas Accretion 

      Evans, D.A.; Hardcastle, M.J.; Croston, J.H. (Astronomical Society of the Pacific, 2008)
      We present results from Chandra and XMM-Newton spectroscopic observations of the nuclei of z < 0.5 radio galaxies and quasars from the 3CRR catalog, and examine in detail the dichotomy in the properties of low- and ...

    • The X-ray nuclei of intermediate-redshift radio sources 

      Hardcastle, M.J.; Evans, D.A.; Croston, J.H. (2006)
      We present a Chandra and XMM-Newton spectral analysis of the nuclei of the radio galaxies and radio-loud quasars from the 3CRR sample in the redshift range 0.1 < z < 0.5. In the range of radio luminosity sampled by these ...

    • XMM-Newton Observations of the Nuclei of the Radio Galaxies 3C 305, DA 240, and 4C 73.08 

      Evans, D.A.; Hardcastle, M.J.; Lee, J.C.; Kraft, R.P.; Worrall, D.M.; Birkinshaw, M.; Croston, J.H. (2008)
      We present new XMM-Newton EPIC observations of the nuclei of the nearby radio galaxies 3C 305, DA 240, and 4C 73.08, and investigate the origin of their nuclear X-ray emission. The nuclei of the three sources appear to ...