Browsing Physics & Atmospheric Science by Author "Lewis, Geraint F."

Now showing items 1-19 of 19

  • B1933+503, a dusty radio quasar at z>2: implications for blank field sub-mm surveys? 

    Chapman, Scott C.; Scott, Douglas; Lewis, Geraint F.; Borys, Colin; Fahlman, Gregory G. (1998-10-27)
    We present a detailed mm-wave and optical study of the gravitational lens system B1933+503, discovered by Sykes et al.(1998) in the radio. This object is probably the most complex lens system known, with 10 lensed components ...

  • A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (Part II); Distances to the Satellites of M31 

    Conn, Anthony R.; Ibata, Rodrigo A.; Lewis, Geraint F.; Parker, Quentin A.; Zucker, Daniel B.; Martin, Nicolas F.; McConnachie, Alan W.; Irwin, Mike J.; Tanvir, Nial; Fardal, Mark A.; Ferguson, Annette M. N.; Chapman, Scott C.; Valls-Gabaud, David (2012-09-21)
    In `A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (PART I),' a new technique was introduced for obtaining distances using the TRGB standard candle. Here we describe a useful complement to the technique ...

  • A Keck/DEIMOS Kinematic Study of Andromeda IX: dark matter on the smallest galactic scales 

    Chapman, Scott C.; Ibata, Rodrigo; Lewis, Geraint F.; Ferguson, Annette M. N.; Irwin, Mike; McConnachie, Alan; Tanvir, Nial (2005-10-20)
    We present the results of a kinematic survey of the dwarf spheroidal satellite of M31, And-IX, which appears to be the lowest surface brightness and also the faintest galaxy (M_V = -8.3) found to date. Using Keck/DEIMOS ...

  • A kinematic study of the Andromeda dwarf spheroidal system 

    Collins, Michelle L. M.; Chapman, Scott C.; Rich, R. Michael; Ibata, Rodrigo A.; Martin, Nicolas F.; Irwin, Michael J.; Bate, Nicholas F.; Lewis, Geraint F.; Peñarrubia, Jorge; Arimoto, Nobuo; Casey, Caitlin M.; Ferguson, Annette M. N.; Koch, Andreas; McConnachie, Alan W.; Tanvir, Nial (2013-02-26)
    We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I LRIS and Keck II DEIMOS spectrographs. Based on their g-i ...

  • The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties 

    Ibata, Rodrigo A.; Lewis, Geraint F.; McConnachie, Alan W.; Martin, Nicolas F.; Irwin, Michael J.; Ferguson, Annette M. N.; Babul, Arif; Bernard, Edouard J.; Chapman, Scott C.; Collins, Michelle; Fardal, Mark; Mackey, A. D.; Navarro, Julio; Penarrubia, Jorge; Rich, R. Michael; Tanvir, Nial; Widro, Lawrence (2013-11-22)
    We present an analysis of the large-scale structure of the halo of the Andromeda galaxy, based on the Pan-Andromeda Archeological Survey (PAndAS), currently the most complete map of resolved stellar populations in any ...

  • The M33 Globular Cluster System with PAndAS Data: The Last Outer Halo Cluster? 

    Cockcroft, Robert; Harris, William E.; Ferguson, Annette M. N.; Huxor, Avon; Ibata, Rodrigo; Irwin, Mike J.; McConnachie, Alan W.; Woodley, Kristin A.; Chapman, Scott C.; Lewis, Geraint F.; Puzia, Thomas H. (2011-01-12)
    We use CFHT/MegaCam data to search for outer halo star clusters in M33 as part of the Pan-Andromeda Archaeological Survey (PAndAS). This work extends previous studies out to a projected radius of 50 kpc and covers over 40 ...

  • The masses of Local Group dwarf spheroidal galaxies: The death of the universal mass profile 

    Collins, Michelle L. M.; Chapman, Scott C.; Rich, R. M.; Ibata, Rodrigo A.; Martin, Nicolas F.; Irwin, Michael J.; Bate, Nicholas F.; Lewis, Geraint F.; Peñarrubia, Jorge; Arimoto, Nobuo; Casey, Caitlin M.; Ferguson, Annette M. N.; Koch, Andreas; McConnachie, Alan W.; Tanvir, Nial (2013-09-12)
    We investigate the claim that all dwarf spheroidal galaxies (dSphs) reside within halos that share a common, universal mass profile as has been derived for dSphs of the Galaxy. By folding in kinematic information for 25 ...

  • Modeling the evolution of infrared luminous galaxies: the influence of the Luminosity-Temperature distribution 

    Lewis, Geraint F.; Chapman, Scott C.; Helou, George (2005-03)
    The evolution of the luminous infrared galaxy population is explored using a pure luminosity evolution model which incorporates the locally observed luminosity-temperature distribution for IRAS galaxies. Pure luminosity ...

  • PAndAS in the mist: The stellar and gaseous mass within the halos of M31 and M33 

    Lewis, Geraint F.; Braun, Robert; McConnachie, Alan W.; Irwin, Michael J.; Ibata, Rodrigo A.; Chapman, Scott C.; Ferguson, Annette M. N.; Martin, Nicolas F.; Fardal, Mark; Dubinski, John; Widrow, Larry; Mackey, A. Dougal; Babul, Arif; Tanvir, Nial; Rich, Michael (2012-11-16)
    Large scale surveys of the prominent members of the Local Group have provided compelling evidence for the hierarchical formation of massive galaxies, revealing a wealth of substructure that is thought to be the debris from ...

  • PAndAS' cubs: discovery of two new dwarf galaxies in the surroundings of the Andromeda and Triangulum galaxies 

    Martin, Nicolas F.; McConnachie, Alan W.; Irwin, Mike; Widrow, Lawrence M.; Ferguson, Annette M. N.; Ibata, Rodrigo A.; Dubinski, John; Babul, Arif; Chapman, Scott; Fardal, Mark; Lewis, Geraint F.; Navarro, Julio; Rich, R. Michael (2009-09-02)
    We present the discovery of two new dwarf galaxies, Andromeda XXI and Andromeda XXII, located in the surroundings of the Andromeda and Triangulum galaxies (M31 and M33). These discoveries stem from the first year data of ...

  • PAndAS' progeny: extending the M31 dwarf galaxy cabal 

    Richardson, Jenny C.; Irwin, Mike; McConnachie, Alan W.; Martin, Nicolas F.; Dotter, Aaron; Ferguson, Annette M. N.; Ibata, Rodrigo A.; Chapman, Scott; Lewis, Geraint F.; Tanvir, Nial R.; Rich, R. Michael (2011-02-14)
    We present the discovery of five new dwarf galaxies, Andromeda XXIII-XXVII, located in the outer halo of M31. These galaxies were found in the second year of data from the Pan-Andromeda Archaeological Survey (PAndAS) of ...

  • SCUBA observations of Hawaii 167 

    Lewis, Geraint F.; Chapman, Scott C. (2000-11)
    We present the first submillimetre observations of the z=2.36 broad absorption line system Hawaii 167. Our observations confirm the hypothesis that Hawaii 167 contains a massive quantity of dust, the optical depth of which ...

  • The Star Formation History and Dust Content in the Far Outer Disc of M31 

    Bernard, Edouard J.; Ferguson, Annette M. N.; Barker, Michael K.; Hidalgo, Sebastian L.; Ibata, Rodrigo A.; Irwin, Michael J.; Lewis, Geraint F.; McConnachie, Alan W.; Monelli, Matteo; Chapman, Scott C. (2011-11-22)
    We present a detailed analysis of two fields located 26 kpc (~5 scalelengths) from the centre of M31. One field samples the major axis populations--the Outer Disc field--while the other is offset by ~18' and samples the ...

  • The stellar halo and outer disk of M33 

    McConnachie, Alan W.; Chapman, Scott C.; Ibata, Rodrigo A.; Ferguson, Annette M. N.; Irwin, Mike J.; Lewis, Geraint F.; Tanvir, Nial R. (2006-08-10)
    We present first results from a Keck/DEIMOS spectroscopic survey of red giant branch (RGB) stars in M33. The radial velocity distributions of the stars in our fields are well described by three Gaussian components, ...

  • Submillimeter Observations of the Ultraluminous BAL Quasar APM 08279+5255 

    Lewis, Geraint F.; Chapman, Scott C.; Ibata, Rodrigo A.; Irwin, Michael J.; Totten, Edward J. (1998-9-20)
    With an inferred bolometric luminosity of $5\times10^{15}{\rm \lsun}$, the recently identified z=3.87, broad absorption line quasar APM 08279+5255 is apparently the most luminous object currently known. As half of its ...

  • Submillimetre observations of a sample of broad absorption line quasars 

    Lewis, Geraint F.; Chapman, Scott C.; Kuncic, Zdenka (2003-10-10)
    The broad absorption line (BAL) features seen in a small fraction of quasar optical/UV spectra are attributed to bulk outflows away from the quasar core. Observational evidence suggests that dust plays a key role in these ...

  • The Three-Dimensional Structure of the M31 Satellite System; Strong Evidence for an Inhomogeneous Distribution of Satellites 

    Conn, Anthony R.; Lewis, Geraint F.; Ibata, Rodrigo A.; Parker, Quentin A.; Zucker, Daniel B.; McConnachie, Alan W.; Martin, Nicolas F.; Valls-Gabaud, David; Tanvir, Nial; Irwin, Michael J.; Ferguson, Annette M. N.; Chapman, Scott C. (2013-01-29)
    We undertake an investigation into the spatial structure of the M31 satellite system utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and ...

  • Understanding the nature of the optically faint radio sources and their connection to the submillimeter population 

    Chapman, Scott C.; Lewis, Geraint F.; Scott, Douglas; Borys, Colin; Richards, Eric A. (2002-05-10)
    We present a sample of 43 submillimeter sources detected (at >3 sigma), drawn from our program to follow-up optically faint radio sources with SCUBA. These sources already have associated radio and in many cases optical ...

  • Unearthing Foundations of a Cosmic Cathedral: Searching the Stars for M33's Halo 

    Cockcroft, Robert; McConnachie, Alan W.; Harris, William E.; Ibata, Rodrigo; Irwin, Mike J.; Ferguson, Annette M. N.; Fardal, Mark A.; Babul, Arif; Chapman, Scott C.; Lewis, Geraint F.; Martin, Nicolas F.; Puzia, Thomas H. (2012-10-29)
    We use data from the Pan-Andromeda Archaeological Survey (PAndAS) to search for evidence of an extended halo component belonging to M33 (the Triangulum Galaxy). We identify a population of red giant branch (RGB) stars at ...