Browsing Research Articles (Physics) by Title

Now showing items 1-20 of 36

  • Black hole - galaxy correlations without self-regulation 

    Angles-Alcazar, Daniel; Ozel, Feryal; Dave, Romeel (American Astronomical Society, 2013)
    Recent models of black hole growth in a cosmological context have forwarded a paradigm in which the growth is self-regulated by feedback from the black hole itself. Here we use cosmological zoom simulations of galaxy formation ...

  • A deep search for faint galaxies associated with very low-redshift C iv absorbers: A case with cold-accretion characteristics 

    Burchett, Joseph N.; Tripp, Todd M.; Werk, Jessica K.; Howk, J. Christopher; Dave, Romeel; Prochaska, J. Xavier; Ford, Amanda Brady (The American Astronomical Society, 2013)
    Studies of QSO absorber–galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO ...

  • Einstein's legacy in galaxy surveys 

    Camera, Stefano; Maartens, Roy; Santos, Mario G. (Oxford University Press, 2015)
    Non-Gaussianity in the primordial fluctuations that seeded structure formation produces a signal in the galaxy power spectrum on very large scales. This signal contains vital information about the primordial Universe, but ...

  • Evolution from 4f-electron antiferromagnetic to ferromagnetic order in the CeCu(Ge1-xSnx) alloy series (0≤x≤1) 

    Altayeb, Anas; Sondezi, B. M.; Tchoula Tchokonte, Moise; Strydom, A. M.; Doyle, T. B.; Kaczorowski, D. (American Institute of Physics Inc., 2017)
    We report the evolution from ferromagnetic (FM) to antiferromagnetic (AFM) state in CeCu(Ge1-xSnx) investigated by means of magnetic and heat capacity measurements. X-ray diffraction studies for all compositions indicate ...

  • Existence domains of dust-acoustic solitons and supersolitons 

    Maharaj, S. K.; Bharuthram, Ramashwar; Singh, S. V.; Lakhina, G. S. (AIP PublishingAIP Publishing, 2013)
    Using the Sagdeev potential method, the existence of large amplitude dust-acoustic solitons and supersolitons is investigated in a plasma comprising cold negative dust, adiabatic positive dust, Boltzmann electrons, and ...

  • The faint radio source population at 15.7 GHz - II. Multi-wavelength properties 

    Whittam, I.H.; Riley, J.M.; Green, D.A.; Jarvis, Matt; Vaccari, M. (Oxford University Press, 2015)
    A complete, flux density limited sample of 96 faint (> 0:5 mJy) radio sources is selected from the 10C survey at 15.7 GHz in the Lockman Hole. We have matched this sample to a range of multi-wavelength catalogues, including ...

  • A framework for assessing the performance of pulsar search pipelines 

    van Heerden, E.; Karastergiou, A.; Roberts, J. (Oxford Unviersity Press, 2016)
    In this paper, we present a framework for assessing the effect of non-stationary Gaussian noise and radio frequency interference (RFI) on the signal to noise ratio, the number of false positives detected per true positive ...

  • Gaia Data Release 1. Open cluster astrometry: performance, limitations, and future prospects 

    van Leeuwen, F.; Vallenari, A.; Vaccari, M. (EDP Sciences, 2017)
    CONTEXT: The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are ...

  • Herschel-atlas/Gama: a difference between star formation rates in strong-line and weak-line radio galaxies 

    Hardcastle, M.J.; Ching, J.H.Y.; Jarvis, Matt (OUP, 2013)
    We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. ...

  • Herschel-ATLAS/GAMA: What determines the far-infrared properties of radio galaxies? 

    Virdee, J.S.; Hardcastle, M.J.; Jarvis, Matt (OUP, 2013)
    We perform a stacking analysis of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) data in order to obtain isothermal dust temperatures and rest-frame luminosities at 250 µm (L250), for a well-defined sample ...

  • The high-ion content and kinematics of low-redshift lyman limit systems 

    Fox, Andrew J.; Lehner, Nicholas; Dave, Romeel; Tumlinson, Jason; Howk, J. Christopher; Tripp, Todd M.; Prochaska, J. Xavier; O'Meara, John M.; Werk, Jessica K.; Bordoloi, Rongmon; Katz, Neal; Oppenheimer, Benjamin D. (The American Astronomical Society, 2013)
    We study the high-ion content and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman limit systems (LLSs) at 0.08 < z < 0.93 observed with the Cosmic Origins Spectrograph on ...

  • High-Precision Branching Ratio Measurement for the Superallowed + Emitter 74Rb 

    Dunlop, R.; Ball, G.C.; Leslie, J.R.; Svensson, C.E.; Towner, I.S.; Andreoiu, C.; Chagnon-Lessard, S.; Chester, A.; Cross, D.S.; Finlay, P.; Garnsworthy, A.B.; Garrett, P.E.; Glister, J.; Hackman, G.; Hadinia, B.; Leach, K. G.; Rand, E.T.; Starosta, K.; Tardiff, E.R.; Triambak, S.; Williams, S. J.; Wong, J.; Yates, S.W.; Zganjar, E.F. (American Physical Society, 2013)
    A high-precision branching-ratio measurement for the superallowed β + decay of 74Rb was performed at the TRIUMF Isotope Separator and Accelerator (ISAC) radioactive ion-beam facility. The scintillating electronpositron tagging ...

  • The host haloes of O I absorbers in the reionization epoch 

    Finlator, Kristian; Muñoz, Joseph A.; Dave, Romeel; Oppenheimer, B. D.; Peng Oh, S.; Özel, Feryal (Oxford University Press, 2013)
    We use a radiation hydrodynamic simulation of the hydrogen reionization epoch to study OI absorbers at z ∼ 6. The intergalactic medium (IGM) is reionized before it is enriched; hence, OI absorption originates within dark ...

  • Hot subdwarf stars in close-up view IV. Helium abundances and the 3He isotopic anomaly of subdwarf B stars 

    Geier, S.; Edelmann, H.; Kilkenny, David; O'Donoghue, D.; Marsh, T.R.; Copperwheat, C. (EDP Sciences, 2013)
    Atmospheric parameters and helium abundances of 44 bright subdwarf B stars have been determined. More than half of our sample consists of newly discovered stars from the Edinburgh Cape survey. We showed that effective ...

  • Hunting down horizon-scale effects with multi-wavelength surveys 

    Fonseca, Jose; Camera, Stefano; Santos, Mario G.; Maartens, Roy (American Astronomical Society, 2015)
    Next-generation cosmological surveys will probe ever larger volumes of the universe, including the largest scales, near and beyond the horizon. On these scales, the galaxy power spectrum carries signatures of local primordial ...

  • Isothermal dust models of Herschel-ATLAS galaxies 

    Smith, D.J.B.; Hardcastle, M.J.; Jarvis, Matt (Oxford University Press, 2013)
    We use galaxies from the Herschel-ATLAS survey, and a suite of ancillary simulations based on an isothermal dust model, to study our ability to determine the effective dust temperature, luminosity and emissivity index of ...

  • Mind the gap: Science and engineering education at the secondary–tertiary interface 

    Case, Jenni; Marshall, Delia; Grayson, Diane (Academy of Science of South Africa, 2013)
    In the South African higher education sector, there is increasing concern about the poor retention and throughput rates of undergraduate students. There is also concern that the participation rates in higher education, ...

  • Mufasa: The assembly of the red sequence 

    Dave, Romeel; Rafieferantso, Mika H.; Thompson, Robert J. (Oxford University Press, 2017)
    We examine the growth and evolution of quenched galaxies in the Mufasa cosmo- logical hydrodynamic simulations that include an evolving halo mass-based quench- ing prescription, with galaxy colours computed accounting ...

  • The neutral hydrogen content of galaxies in cosmological hydrodynamic simulations 

    Dave, Romeel; Katz, Neal; Oppernheimer, Benjamin D.; Kollmeier, Juna A.; Weinberg, David H. (Oxford University Press, 2013)
    We examine the global HI properties of galaxies in quarter billion particle cosmological simulations using GADGET-2, focusing on howgalactic outflows impactHI content.We consider four outflow models, including a new one ...

  • Nonlinear modulation of the HI power spectrum on ultra-large scales. I 

    Umeh, Obinna; Maartens, Roy; Santos, Mario G. (IOP Science, 2015)
    Intensity mapping of the neutral hydrogen brightness temperature promises to provide a three-dimensional view of the universe on very large scales. Nonlinear effects are typically thought to alter only the small-scale ...