arXiv subjects

Alfonso Veropalumbo

Publications and source records attributed to Alfonso Veropalumbo.

21 records · Page 2Linked to original sources

arXiv2016

CosmoBolognaLib: C++ libraries for cosmological calculations

We present the CosmoBolognaLib, a large set of Open Source C++ numerical libraries for cosmological calculations. CosmoBolognaLib is a living project aimed at defining a common numerical environment for cosmological investigations of the large-scale structure of the Universe. In particular, one of the primary focuses of this software is to help in handling astronomical catalogues, both real and simulated, measuring one-point, two-point and three-point statistics in configuration space, and performing cosmological analyses. In this paper, we discuss the main features of this software, providing an overview of all the available C++ classes implemented up to now. Both the CosmoBolognaLib and their associated doxygen documentation can be freely downloaded at https://github.com/federicomarulli/CosmoBolognaLib. We provide also some examples to explain how these libraries can be included in either C++ or Python codes.

astro-ph.CO↗

arXiv2015

Measuring the distance-redshift relation with the baryon acoustic oscillations of galaxy clusters

We analyse the largest spectroscopic samples of galaxy clusters to date, and provide observational constraints on the distance-redshift relation from baryon acoustic oscillations. The cluster samples considered in this work have been extracted from the Sloan Digital Sky Survey at three median redshifts, $z=0.2$, $z=0.3$, and $z=0.5$. The number of objects is $12910$, $42215$, and $11816$, respectively. We detect the peak of baryon acoustic oscillations for all the three samples. The derived distance constraints are: $r_s/D_V(z=0.2)=0.18 \pm 0.01$, $r_s/D_V(z=0.3)=0.124 \pm 0.004$ and $r_s/D_V(z=0.5)=0.080 \pm 0.002$. Combining these measurements, we obtain robust constraints on cosmological parameters. Our results are in agreement with the standard $Λ$ cold dark matter model. Specifically, we constrain the Hubble constant in a $Λ$CDM model, $H_0 = 64_{-9}^{+14} \, \mathrm{km} \, \mathrm{s}^{-1}\mathrm{Mpc}^{-1}$, the density of curvature energy, in the $oΛ$CDM context, $Ω_K = -0.015_{-0.36}^{+0.34}$, and finally the parameter of the dark energy equation of state in the $ow$CDM case, $w = -1.01_{-0.44}^{+0.44}$. This is the first time the distance-redshift relation has been constrained using only the peak of baryon acoustic oscillations of galaxy clusters.

astro-ph.CO↗

arXiv2015

New constraints on $σ_8$ from a joint analysis of stacked gravitational lensing and clustering of galaxy clusters

The joint analysis of clustering and stacked gravitational lensing of galaxy clusters in large surveys can constrain the formation and evolution of structures and the cosmological parameters. On scales outside a few virial radii, the halo bias, $b$, is linear and the lensing signal is dominated by the correlated distribution of matter around galaxy clusters. We discuss a method to measure the power spectrum amplitude $σ_8$ and $b$ based on a minimal modelling. We considered a sample of $\sim 120000$ clusters photometrically selected from the Sloan Digital Sky Survey in the redshift range $0.1<z<0.6$. The auto-correlation was studied through the two-point function of a subsample of $\sim 70000$ clusters; the matter-halo correlation was derived from the weak lensing signal of the subsample of $\sim 1200$ clusters with Canada-France-Hawaii Lensing Survey data. We obtained a direct measurement of $b$, which increases with mass in agreement with predictions of the $Λ$CDM paradigm. Assuming $Ω_\mathrm{M}=0.3$, we found $σ_8=0.78\pm0.16$. We used the same clusters for measuring both lensing and clustering and the estimate of $σ_8$ did require neither the mass-richness relation, nor the knowledge of the selection function, nor the modelling of $b$. With an additional theoretical prior on the bias, we obtained $σ_8=0.75\pm0.08$.

astro-ph.CO↗