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 $\Lambda$CDM model, confirming a mild tension between cosmic microwave background predictions from Planck mission and cosmic growth measurements at low redshift ($z<2$). 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 $\gamma=0.65^{+0.05}_{-0.04}$). However, also a standard model with total neutrino mass of $0.26\pm0.10$ 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 $z>1$ will be crucial to discriminate between alternative models.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS lette