Topic
Cosmology
About: Cosmology is a research topic. Over the lifetime, 18004 publications have been published within this topic receiving 631028 citations. The topic is also known as: physical cosmology & cosmologies.
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TL;DR: In this article, the authors explore the possibility that a new universe can be created by producing a small bubble of false vacuum, which would then evolve to a larger bubble of the same mass.
246 citations
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TL;DR: In this article, the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to β decay and double-beta decay experiments.
Abstract: Neutrinos can play an important role in the evolution of the Universe,
modifying some of the cosmological observables In this contribution we
summarize the main aspects of cosmological relic neutrinos and we describe how
the precision of present cosmological data can be used to learn about neutrino
properties, in particular their mass, providing complementary information to
beta decay and neutrinoless double-beta decay experiments We show how the
analysis of current cosmological observations, such as the anisotropies of the
cosmic microwave background or the distribution of large-scale structure,
provides an upper bound on the sum of neutrino masses of order 1 eV or less,
with very good perspectives from future cosmological measurements which are
expected to be sensitive to neutrino masses well into the sub-eV range
246 citations
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TL;DR: Colossus as discussed by the authors is a Python package for calculations related to cosmology, the large-scale structure (LSS) of matter in the universe, and the properties of dark matter halos.
Abstract: This paper introduces Colossus, a public, open-source python package for calculations related to cosmology, the large-scale structure (LSS) of matter in the universe, and the properties of dark matter halos. The code is designed to be fast and easy to use, with a coherent, well-documented user interface. The cosmology module implements Friedman–Lemaitre–Robertson–Walker cosmologies including curvature, relativistic species, and different dark energy equations of state, and provides fast computations of the linear matter power spectrum, variance, and correlation function. The LSS module is concerned with the properties of peaks in Gaussian random fields and halos in a statistical sense, including their peak height, peak curvature, halo bias, and mass function. The halo module deals with spherical overdensity radii and masses, density profiles, concentration, and the splashback radius. To facilitate the rapid exploration of these quantities, Colossus implements more than 40 different fitting functions from the literature. I discuss the core routines in detail, with particular emphasis on their accuracy. Colossus is available at bitbucket.org/bdiemer/colossus.
245 citations
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TL;DR: In this paper, the authors use the joint measurement of geometry and growth from anisotropic galaxy clustering in the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) CMASS sample reported by Reid et al. to constrain dark energy (DE) properties and possible deviations from the general relativity (GR) assuming GR and taking a prior on the linear matter power spectrum at high redshift from the cosmic microwave background (CMB).
Abstract: We use the joint measurement of geometry and growth from anisotropic galaxy clustering in the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) CMASS sample reported by Reid et al to constrain dark energy (DE) properties and possible deviations from the general relativity (GR) Assuming GR and taking a prior on the linear matter power spectrum at high redshift from the cosmic microwave background (CMB), anisotropic clustering of the CMASS DR9 galaxies alone constrains Ωm = 0308 ± 0022 and 100Ωk = 59 ± 48 for w = −1, or w = −091 ± 012 for Ωk = 0 When combined with the full CMB likelihood, the addition of the anisotropic clustering measurements to the spherically averaged baryon acoustic oscillation location increases the constraining power on DE by a factor of 4 in a flat cold dark matter (CDM) cosmology with constant DE equation of state w (giving w = −087 ± 005) This impressive gain depends on our measurement of both the growth of structure and the Alcock–Paczynski effect, and is not realized when marginalizing over the amplitude of redshift-space distortions Combining with both the CMB and Type Ia supernovae, we find Ωm = 0281 ± 0014 and 1000Ωk = −92 ± 50 for w = −1, or w0 = −113 ± 012 and wa = 065 ± 036 assuming Ωk = 0 Finally, when a ΛCDM background expansion is assumed, the combination of our estimate of the growth rate with previous growth measurements provides tight constraints on the parameters describing possible deviations from GR giving γ = 064 ± 005 For one-parameter extensions of the flat ΛCDM model, we find a ∼2σ preference either for w > −1 or slower growth than in GR However, the data are fully consistent with the concordance model, and evidence for these additional parameters is weaker than 2σ
244 citations
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TL;DR: In this paper, the authors use high-resolution N-body simulations of galactic dark matter haloes to test if this remarkable property can be understood within the context of the cold dark matter (CDM) cosmology.
Abstract: The 11 known satellite galaxies within 250 kpc of the Milky Way lie close to a great circle on the sky. We use high-resolution N-body simulations of galactic dark matter haloes to test if this remarkable property can be understood within the context of the cold dark matter (CDM) cosmology. We construct halo merger trees from the simulations and use a semi-analytic model to follow the formation of satellite galaxies. We find that in all six of our simulations, the 11 brightest satellites are indeed distributed along thin, disc-like structures analogous to that traced by the satellites of the Milky Way. This is in sharp contrast to the overall distributions of dark matter in the halo and of subhaloes within it, which, although triaxial, are not highly aspherical. We find that the spatial distribution of satellites is significantly different from that of the most massive subhaloes but is similar to that of the subset of subhaloes that had the most massive progenitors at earlier times. The elongated disc-like structure delineated by the satellites has its long axis aligned with the major axis of the dark matter halo. We interpret our results as reflecting the preferential infall of satellites along the spines of a few filaments of the cosmic web.
244 citations