Suchergebnisse

Some of the most important quintessential inflation scenarios, such as the Peebles–Vilenkin model, are described in detail. These models are able to explain the early- and late-time accelerated expansions of our universe, and the phase transition from the end of inflation to the beginning of kination where the adiabatic evolution of the universe was broken in order to produce enough particles to reheat the universe with a viable temperature, thereby aligning with the Hot Big Bang universe. In addition, while considering the reheating to be due to the gravitational production of superheavy particles conformally coupled to gravity, we checked that the considered scenarios do not suffer problems due to the overproduction of gravitational waves at the end of inflation, and thus the validity of Big Bang nucleosynthesis is preserved ; The investigation of J.d.H. has been supported by MINECO (Spain) grant MTM2017-84214-C2-1-P, and in part by the Catalan Government 2017-SGR-247 ; Peer Reviewed ; Postprint (published version)

The relation between the reheating temperature, the number of e-folds and the spectral index is shown for the Starobinsky model and some of its descendants through a very detailed calculation of these three quantities. The conclusion is that for viable temperatures between 1 MeV and 109 GeV the corresponding values of the spectral index enter perfectly in its 2s C.L., which shows the viability of this kind of models ; This investigation has been supported by MINECO (Spain) Grant MTM2017-84214-C2-1-P and in part by the Catalan Government 2017-SGR-247. ; Peer Reviewed ; Postprint (published version)

The dynamics of interacting dark matter-dark energy models is characterized through an interaction rate function quantifying the energy flow between these dark sectors. In most of the interaction functions, the expansion rate Hubble function is considered and sometimes it is argued that, as the interaction function is a local property, the inclusion of the Hubble function may influence the overall dynamics. This is the starting point of the present article where we consider a very simple interacting cosmic scenario between vacuum energy and the cold dark matter characterized by various interaction functions originated from a general interaction function. ; J.dH. has been supported by MINECO (Spain) Grant No. MTM2017-84214-C2-1-P, and in part by the Catalan Government 2017-SGR-247 ; Peer Reviewed ; Postprint (published version)

An exponential kind of quintessential inflation potential motivated by supergravity is studied. This type belongs to the class of a-attractor models. The model was studied for the first time by Dimopoulos and Owen in [J. Cosmol. Astropart. Phys. 06 (2017) 027], in which the authors introduced a negative cosmological constant in order to ensure a zero-vacuum energy density at late times. However, in this paper, we disregard this cosmological constant, showing that the obtained results are very close to the ones obtained recently in the context of Lorentzian quintessential inflation and thus depicting with great accuracy the early- and late-time acceleration of our Universe. The model is compatible with the recent observations. Finally, we review the treatment of the a-attractor and we show that our potential depicts the late time cosmic acceleration with an effective equation of state equal to -1 ; The investigation of J. d. H. has been supported byMINECO (Spain) Grant No.MTM2017-84214- C2-1-P and in part by the Catalan Government Grant NO. 2017-SGR-247 ; Peer Reviewed ; Postprint (published version)

Recently a new kind of quintessential inflation coming from the Lorentzian distribution has been introduced in [1,2]. The model leads to a very simple potential, which basically depends on two parameters, belonging to the class of a-attractors and depicting correctly the early and late time accelerations of our universe. The potential emphasizes a cosmological seesaw mechanism (CSSM) that produces a large inflationary vacuum energy in one side of the potential and a very small value of dark energy on the right hand side of the potential. Here we show that the model agrees with the recent observations and with the reheating constraints. Therefore the model gives a reasonable scenario beyond the standard ¿CDM that includes the inflationary epoch ; The investigation of J. de Haro has been supported by MINECO (Spain) grant MTM2017-84214-C2-1-P and in part by the Catalan Government 2017-SGR-247 ; Peer Reviewed ; Postprint (author's final draft)