arXiv subjects

Pedro C. Ferreira

Publications and source records attributed to Pedro C. Ferreira.

3 recordsLinked to original sources

arXiv2016

Thermodynamics of nonsingular bouncing universes

Homogeneous and isotropic, nonsingular, bouncing world models are designed to evade the initial singularity at the beginning of the cosmic expansion. Here, we study the thermodynamics of the subset of these models governed by general relativity. Considering the entropy of matter, radiation and that the entropy of the apparent horizon is proportional to its area, we argue that these models do not respect the generalised second law of thermodynamics, also away from the bounce.

gr-qc↗

arXiv2013

On detecting interactions in the dark sector with H(z) data

An interesting approach to the cosmological coincidence problem is to allow dark matter and dark energy interact with each other also nongravitationally. We consider two general Ansätze for such an interaction and appraise their ability to address the coincidence problem. We determine the average accuracy required on the cosmic expansion rate data to distinguish interacting cosmological models from the conventional $Λ$CDM scenario. We find that among the planned surveys the Wide Field Infrared Survey Telescope has the best chance to detect an interaction, though at a low significance level. To unambiguously determine the existence of an interaction one must, therefore, combine the said expansion data with other probes.

gr-qc↗

arXiv2012

Modeling and Analysis Generic Interface for eXternal numerical codes (MAGIX)

The modeling and analysis generic interface for external numerical codes (MAGIX) is a model optimizer developed under the framework of the coherent set of astrophysical tools for spectroscopy (CATS) project. The MAGIX package provides a framework of an easy interface between existing codes and an iterating engine that attempts to minimize deviations of the model results from available observational data, constraining the values of the model parameters and providing corresponding error estimates. Many models (and, in principle, not only astrophysical models) can be plugged into MAGIX to explore their parameter space and find the set of parameter values that best fits observational/experimental data. MAGIX complies with the data structures and reduction tools of ALMA (Atacama Large Millimeter Array), but can be used with other astronomical and with non-astronomical data.

astro-ph.IM↗