24 research outputs found
Coupled dark energy: a dynamical analysis with complex scalar field
The dynamical analysis for coupled dark energy with dark matter is presented,
where a complex scalar field is taken into account and it is considered in the
presence of a barothropic fluid. We consider three dark energy candidates:
quintessence, phantom and tachyon. The critical points are found and their
stabilities analyzed, leading to the three cosmological eras (radiation, matter
and dark energy), for a generic potential. The results presented here enlarge
the previous analyses found in the literature.Comment: 9 pages, version accepted for publication in EPJC. arXiv admin note:
text overlap with arXiv:1505.0324
Dynamical analysis for a vector-like dark energy
In this paper we perform a dynamical analysis for a vector field as a
candidate for the dark energy, in the presence of a barothropic fluid. The
vector is one component of the so-called cosmic triad, which is a set of three
identical copies of an abelian field pointing mutually in orthogonal
directions. In order to generalize the analysis, we also assumed the
interaction between dark energy and the barotropic fluid, with a
phenomenological coupling. Both matter and dark energy eras can be successfully
described by the critical points, indicating that the dynamical system theory
is a viable tool to analyze asymptotic states of such cosmological models.Comment: 6 pages, 3 figures, version to appear in EPJ
Cosmological tracking solution and the Super-Higgs mechanism
In this paper we argue that minimal supergravity with flat K\"ahler metric
and a power-law superpotential can relate the Super-Higgs mechanism for the
local spontaneous supersymmetry breaking and the cosmological tracking
solution, leading in turn to a late-time accelerated expansion of the universe
and alleviating the coincidence problem.Comment: 5 pages, 1 figure, minor corrections, to appear in EPJ
Interacting Dark Energy: Possible Explanation for 21-cm Absorption at Cosmic Dawn
A recent observation points to an excess in the expected 21-cm brightness
temperature from cosmic dawn. In this paper, we present an alternative
explanation of this phenomenon, an interaction in the dark sector. Interacting
dark energy models have been extensively studied recently and there is a whole
variety of such in the literature. Here we particularize to a specific model in
order to make explicit the effect of an interaction.Comment: 5 pages, 2 figures. Discussion improved, new references, conclusions
unchanged. Accepted in EPJ
The BINGO Project IX: Search for Fast Radio Bursts -- A Forecast for the BINGO Interferometry System
The Baryon Acoustic Oscillations (BAO) from Integrated Neutral Gas
Observations (BINGO) radio telescope will use the neutral Hydrogen emission
line to map the Universe in the redshift range , with
the main goal of probing BAO. In addition, the instrument optical design and
hardware configuration support the search for Fast Radio Bursts (FRBs). In this
work, we propose the use of a BINGO Interferometry System (BIS) including new
auxiliary, smaller, radio telescopes (hereafter \emph{outriggers}). The
interferometric approach makes it possible to pinpoint the FRB sources in the
sky. We present here the results of several BIS configurations combining BINGO
horns with and without mirrors ( m, m, and m) and 5, 7, 9, or 10 for
single horns. We developed a new {\tt Python} package, the {\tt FRBlip}, which
generates synthetic FRB mock catalogs and computes, based on a telescope model,
the observed signal-to-noise ratio (S/N) that we used to compute numerically
the detection rates of the telescopes and how many interferometry pairs of
telescopes (\emph{baselines}) can observe an FRB. FRBs observed by more than
one baseline are the ones whose location can be determined. We thus evaluate
the performance of BIS regarding FRB localization. We found that BIS will be
able to localize 23 FRBs yearly with single horn outriggers in the best
configuration (using 10 outriggers of 6 m mirrors), with redshift ; the full localization capability depends on the number and the type of
the outriggers. Wider beams are best to pinpoint FRB sources because potential
candidates will be observed by more baselines, while narrow beams look deep in
redshift. The BIS can be a powerful extension of the regular BINGO telescope,
dedicated to observe hundreds of FRBs during Phase 1. Many of them will be well
localized with a single horn + 6 m dish as outriggers.(Abridged)Comment: 12 pages, 9 figures, 5 tables, submitted to A&