Now showing items 1-12 of 12

  • Anti-lensing: the bright side of voids 

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma (American Physical Society, 2013)
    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magni ca- tion e ect from those under-dense regions is generally thought to give a small dimming contribution: objects on the far side ...
  • Clustering of quintessence on horizon scales and its imprint on HI intensity mapping 

    Duniya, Didam G.A.; Bertacca, Daniele; Maartens, Roy (IOP Science, 2013)
    Quintessence can cluster only on horizon scales. What is the effect on the observed matter distribution? To answer this, we need a relativistic approach that goes beyond the standard Newtonian calculation and deals properly ...
  • 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 ...
  • Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle 

    February, Sean; Clarkson, Chris; Maartens, Roy (IOP Science, 2013)
    A suggested solution to the dark energy problem is the void model, where accelerated expansion is replaced by Hubble-scale inhomogeneity. In these models, density perturbations grow on a radially inhomogeneous background. ...
  • 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 ...
  • The kinematic dipole in galaxy redshift surveys 

    Maartens, Roy; Clarkson, Chris; Chen, Song (IOP Publishing, 2018)
    In the concordance model of the Universe, the matter distribution { as observed in galaxy number counts or the intensity of line emission (such as the 21cm line of neutral hydrogen) - should have a kinematic dipole due ...
  • 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 ...
  • Null tests of the cosmological constant using supernovae 

    Yahya, Sahba; Seikel, Marina; Clarkson, Chris; Maartens, Roy; Smith, Mathew (American Physical Society, 2014)
    The standard concordance model of the Universe is based on the cosmological constant as the driver of accelerating expansion. This concordance model is being subjected to a growing range of inter-locking observations. ...
  • The observed galaxy bispectrum from single-field inflation in the squeezed limit 

    Koyama, Kazuya; Umeh, Obinna; Maartens, Roy; Bertacca, Daniele (IOP Publishing, 2018)
    Using the consistency relation in Fourier space, we derive the observed galaxy bispectrum from single- eld in ation in the squeezed limit, in which one of the three modes has a wavelength much longer than the other two. ...
  • Probing the imprint of interacting dark energy on very large scales 

    Duniya, Didam, G. A.; Bertacca, Daniele; Maartens, Roy (American Physical Society, 2015)
    The observed galaxy power spectrum acquires relativistic corrections from light-cone effects, and these corrections grow on very large scales. Future galaxy surveys in optical, infrared and radio bands will probe increasingly ...
  • Synergies between intensity maps of hydrogen lines 

    Fonseca, Jose; Maartens, Roy; Santos, Mario G. (Oxford University Press, 2018)
    We study synergies between Hi 21cm and Hα intensity map observations, focusing on SKA1- like and SPHEREx-like surveys. We forecast how well such a combination can measure features in the angular power spectrum on the ...
  • Testing homegeneity with Galaxy Star formation histories 

    Hoyle, Ben; Jimenez, Raul; Maartens, Roy; Heavens, Alan; Clarkson, Chris; Tojeiro, Rita (IOP Publishing, 2013)
    Observationally confirming spatial homogeneity on sufficiently large cosmological scales is of importance to test one of the underpinning assumptions of cosmology, and is also imperative for correctly interpreting dark ...