Browsing by Author "Baugh, C. M."

Now showing 1 - 6 of 6
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    Constraints on the dark energy equation of state from the imprint of baryons on the power spectrum of clusters
    (2005) Angulo, R.; Baugh, C. M.; Frenk, C. S.; Bower, R. G.; Jenkins, A.; Morris, S. L.
    Acoustic oscillations in the baryon-photon fluid leave a signature in the matter power spectrum. The overall shape of the spectrum and the wavelength of the oscillations depend upon the sound horizon scale at recombination. Using the Lambda cold dark matter Hubble Volume simulation, we show that the imprint of baryons is visible in the power spectrum of cluster-mass dark matter haloes, in spite of significant differences between the halo power spectrum and the prediction of linear perturbation theory. A measurement of the sound horizon scale can constrain the dark energy equation of state. We show that a survey of clusters at intermediate redshift (z similar to 1), like the Sunyaev-Zel'dovich survey proposed by the South Pole Telescope or a red sequence photometric survey with VISTA or the Dark Energy Survey, could potentially constrain the sound horizon scale to an accuracy of similar to 2 per cent, in turn fixing the ratio of the pressure of the dark energy to its density (w) to better than similar to 10 per cent. Our approach does not require knowledge of the cluster mass, unlike those that depend upon the abundance of clusters.
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    Halo merger tree comparison: impact on galaxy formation models
    (2022) Gomez, Jonathan S.; Padilla, N. D.; Helly, J. C.; Lacey, C. G.; Baugh, C. M.; Lagos, C. D. P.
    We examine the effect of using different halo finders and merger tree building algorithms on galaxy properties predicted using the galform semi-analytical model run on a high resolution, large volume dark matter simulation. The halo finders/tree builders hbt, rockstar, subfind, and VELOCI raptor differ in their definitions of halo mass, on whether only spatial or phase-space information is used, and in how they distinguish satellite and main haloes; all of these features have some impact on the model galaxies, even after the trees are post-processed and homogenized by galform. The stellar mass function is insensitive to the halo and merger tree finder adopted. However, we find that the number of central and satellite galaxies in galform does depend slightly on the halo finder/tree builder. The number of galaxies without resolved subhaloes depends strongly on the tree builder, with VELOCIraptor, a phase-space finder, showing the largest population of such galaxies. The distributions of stellar masses, cold and hot gas masses, and star formation rates agree well between different halo finders/tree builders. However, because VELOCIraptor has more early progenitor haloes, with these trees galform produces slightly higher star formation rate densities at high redshift, smaller galaxy sizes, and larger stellar masses for the spheroid component. Since in all cases these differences are small we conclude that, when all of the trees are processed so that the main progenitor mass increases monotonically, the predicted galform galaxy populations are stable and consistent for these four halo finders/tree builders.
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    Narrow-band surveys for very high redshift Lyman-alpha emitters
    (EDP SCIENCES S A, 2007) Nilsson, K. K.; Orsi, A.; Lacey, C. G.; Baugh, C. M.; Thommes, E.
    Context. Many current and future surveys aim to detect the highest redshift ( z greater than or similar to 7) sources through their Lyman-alpha (Ly alpha) emission, using the narrow- band imaging method. However, to date the surveys have only yielded non- detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies.
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    The effect of assembly bias on redshift-space distortions
    (2019) Padilla, Nelson; Contreras, S.; Zehavi, I.; Baugh, C. M.; Norberg, P.
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    The evolution of assembly bias
    (2019) Contreras, S.; Zehavi, I.; Padilla, Nelson; Baugh, C. M.; Jiménez, E.; Lacerna Zambrano, Iván Andrés
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    The galaxy-dark matter halo connection : which galaxy properties are correlated with the host halo mass?
    (2015) Contreras, S.; Baugh, C. M.; Norberg, P.; Padilla, Nelson