1,328 research outputs found
Cosmological exploitation of cosmic void statistics - New numerical tools in the CosmoBolognaLib to extract cosmological constraints from the void size function
We present new numerical tools to analyse cosmic void catalogues, implemented
inside the CosmoBolognaLib, a large set of Open Source C++/Python numerical
libraries. The CosmoBolognaLib provides a common numerical environment for
cosmological calculations. This work extends these libraries by adding new
algorithms for cosmological analyses of cosmic voids, covering the existing gap
between theory and observations. We implemented new methods to model the size
function of cosmic voids, in both observed and simulated samples of dark matter
and biased tracers. Moreover, we provide new numerical tools to construct
unambiguous void catalogues. The latter are designed to be independent of the
void finder, in order to allow a high versatility in comparing independent
results. The implemented Open Source software is available at the GitHub
repository https://github.com/federicomarulli/CosmoBolognaLib. We provide also
a full doxygen documentation and some example codes that explain how to use
these libraries.Comment: 8 pages, 5 figures, reviewed version published in Astronomy &
Astrophysic
Cosmological constraints from a joint analysis of cosmic growth and expansion
Combining measurements on the expansion history of the Universe and on the
growth rate of cosmic structures is key to discriminate between alternative
cosmological frameworks and to test gravity. Recently, Linder (2017) proposed a
new diagram to investigate the joint evolutionary track of these two
quantities. In this letter, we collect the most recent cosmic growth and
expansion rate datasets to provide the state-of-the-art observational
constraints on this diagram. By performing a joint statistical analysis of both
probes, we test the standard CDM model, confirming a mild tension
between cosmic microwave background predictions from Planck mission and cosmic
growth measurements at low redshift (). Then we test alternative models
allowing the variation of one single cosmological parameter at a time. In
particular, we find a larger growth index than the one predicted by general
relativity ). However, also a standard model with
total neutrino mass of eV provides a similarly accurate
description of the current data. By simulating an additional dataset consistent
with next-generation dark-energy mission forecasts, we show that growth rate
constraints at will be crucial to discriminate between alternative
models.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS lette
Cosmic voids in coupled dark energy cosmologies: the impact of halo bias
In this work we analyse the properties of cosmic voids in standard and
coupled dark energy cosmologies. Using large numerical simulations, we
investigate the effects produced by the dark energy coupling on three
statistics: the filling factor, the size distribution and the stacked profiles
of cosmic voids. We find that the bias of the tracers of the density field used
to identify the voids strongly influences the properties of the void
catalogues, and, consequently, the possibility of using the identified voids as
a probe to distinguish coupled dark energy models from the standard CDM cosmology. In fact, on one hand coupled dark energy models are
characterised by an excess of large voids in the cold dark matter distribution
as compared to the reference standard cosmology, due to their higher
normalisation of linear perturbations at low redshifts. Specifically, these
models present an excess of large voids with Mpc h^{-1},
at , respectively. On the other hand, we do not find any
significant difference in the properties of the void detected in the
distribution of collapsed dark matter halos. These results imply that the
tracer bias has a significant impact on the possibility of using cosmic void
catalogues to probe cosmology.Comment: 11 pages, 8 figures and 2 tables. Submitted to MNRA
The Parable of the Tares and Matthew\u27s Stratagy Vis-a-Vis Extreme Sectarian Impulses From Within His Community
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