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Víctor Cárdenas

Publications and source records attributed to Víctor Cárdenas.

3 recordsLinked to original sources

Approximations for the divergence of the local large-scale structure velocity field and its implications for Tilted Cosmology

We characterize the peculiar velocity field of the local large-scale structure reconstructed from the $2M++$ survey, by treating it as a fluid, extracting the divergence via different approximations over a range pf averaged scales. This reconstructed field is important for cosmology, since it was used to correct the peculiar redshifts of the last SNIA compilation Pantheon+. The results have intriguing implications for the LLSS fluid dynamics and particularly for the ``Tilted Cosmology'' model, although those results have to be taken carefully as the velocity field could contain significant bias due to the reconstruction procedure. Those possible bias and its influence in our results are discussed. Representative values of the apparent deceleration parameter ($\Tilde{q}$) are computed, in order to compare our results with the theoretical predictions of the tilted-universe scenario. We conclude that better velocity field reconstructions are necessary in order to constrain the parameters implied in LLSS research and alternative cosmologies.

astro-ph.CO↗

Stealth's cosmologies

We present a novel approach to construct cosmological models endowed with a particular scalar field, the stealth. The model is constructed by studying a scalar field no-minimally coupled to the gravitational field with sources; as sources, we used a perfect fluid and analyzed the simplest case of dust and the power-law cosmology. Surprisingly, we find that these stealth fields, which have no back-reaction to background space-time, have a contribution to cosmological dynamics. Furthermore, we provide analytic expressions of the stealth's contributions to the energy density in both cases, and for the pressure in the power-low cosmology, which means that such contributions to cosmological evolution are quantifiable. Additionally, we discuss the behaviors of the self-interaction potential for some cases.

gr-qc↗

Semi-holographic model including the radiation component

In this letter we study the semi holographic model which corresponds to the radiative version of the model proposed by Zhang et al. (Phys. Lett. B 694 (2010), 177) and revisited by Cárdenas et al. (Mon. Not. Roy. Astron. Soc. 438 (2014), 3603). This inclusion makes the model more realistic, so allows us to test it with current observational data and then answer if the inconsistency reported by Cárdenas et al. is relaxed.

gr-qc↗