submm-faint, star forming radio galaxies

(3''x3'' HST/ACS images of our z~2 SFRGs with contours showing 0.3'' MERLIN radio in overlay)

NAM Press Release   1 April 2008
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Cambridge Press Release   3 April 2008

  • New molecular gas and high resolution radio observations confirm a population of distant star forming galaxies similar to the ultraluminous ``submm galaxies'' (SMGs), but having slightly hotter temperatures.
  • The resulting lower submm fluxes mean these galaxies have gone largely unrecognized previously.
  • The volume density of this new `hot' population is uncertain, yet could contribute to the star formation rate density at z~2 just as significantly as SMGs.

    Confirming a Population of Hot-dust Dominated, Star Forming Ultraluminous Galaxies at High-Redshift
    Casey et al. 2009b (astro-ph/0906.5346) MNRAS in press

    Constraining star formation and AGN in z~2 massive galaxies using high-resolution MERLIN radio observations
    Casey et al. 2009a (astro-ph/0902.1528) MNRAS 395, 1249

    Interferometric CO Observations of submillimeter-faint, radio-selected starburst galaxies at z~2
    Chapman et al. 2008 (astro-ph/0807.3674) ApJ 689, 889

  • SFRGs

    The double radio components shown above (coupled with the HST/ACS 'disturbed' galaxy imagery) represent dramatic merging events in the early universe. Here we see them in submm-faint, star forming radio galaxies (SFRGs) whose classifications were unclear until high resolution radio distinguished these disturbed systems from AGN and otherwise relaxed star forming systems. Our observations suggest that such collisions probably triggered extreme black hole and galaxy growth in the early Universe, setting the stage for the birth of quasars.

    Where do they fit in with SMGs, and AGN radio sources?
           This is what we think.

    ongoing projects
    are found here. they include:

    (Simulation Credit: Tiziana Di Matteo (MPE/CMU), Volker Springel (MPE) & Lars Hernquist (Harvard))

    A simulation of two massive merging galaxies shows the probable history and fate of most SFRGs. In this movie, the brightness represents gas density while the color indicates temperature in the gas distribution.


    Scott Chapman & Caitlin Casey of Cambridge University
    Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK   
    tel (44) 1223 313290 or (44) 1223 766653

    Tom Muxlow & Rob Beswick of Jodrell Bank Observatory
    University of Manchester, Macclesfield, SK11 9DL, UK

    Ian Smail of the University of Durham
    Institute for Computational Cosmology, South Road, Durham DH1 3LE, UK

    Rob Ivison of the University of Edinburgh
    Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

    Andrew Blain of Caltech
    California Institute of Technology, Pasadena, CA, 91125, USA

    Frank Bertoldi of the University of Bonn, Germany

    Last revised: 1st of April, 2009