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Astronomy & Astrophysics

The sources of extended continuum emission towards Q0151+048A:
The host galaxy and the Damped Ly Absorber +

J.U. Fynbo1,2, I. Burud3, Palle Møller2,

1 Institute of Physics and Astronomy, University of Århus C, Denmark
2 European Southern Observatory, Karl-Schwarzschild-StraBe 2, D-85748, Garching by Müchen, Germany
3 Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium

+ Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatotio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.


     We present deep imaging in the U, B and I bands obtained under excellent seeing conditions of the double quasar Q0151+048A,B and of the Damped Ly (DLA) absorbing galaxy at zabs = 1.9342 named S4.

     A detailed analysis of the images reveal, somewhat surprisingly, that extended objects centred on the quasars themselves are much brighter continuum sources than the DLA galaxy. Due to the complexity caused by the many superimposed objects, we are unable to certify whether or not continuum emission from the DLA galaxy is detected.

     The extended objects centred on the positions of the quasars are tentatively identified as the "host galaxies" of the quasars. The flux of those host galaxies is 2-6% of the quasar flux, and the light profile of the brightest one is clearly best fit with a de Vaucouleurs profile. We discuss two alternative interpretations of the origin of the extended flux: i) the early stage of a massive elliptical galaxy in the process of forming the bulk of its stars, or ii) quasar light scattered by dust.

Key Words

quasars: absorption lines - quasars: Q0151+048 - galaxies: intergalactic medium -
galaxies: photometry - methods: data analysis

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