We investigate observational constraints on cosmological parameters combining 15 measurements of the transversal BAO scale (obtained free any fiducial cosmology) with Planck-CMB data to explore parametric space some models. how much Planck + can constraint minimum $\Lambda$CDM model, and extensions, including neutrinos mass $M_{\nu}$, possibility for a dynamical dark energy (DE) scenario. Assuming cosmology, we find $H_0 = 69.23 \pm 0.50$ km s${}^{-1}$ Mpc${}^{-1}$, $M_{\nu} < 0.11$ eV...

We show that the 32 $H(z)$ data from cosmic chronometers have overestimated uncertainties and make use of a Bayesian method to correct reduce it. then corrected constrain flat $\Lambda$CDM O$\Lambda$CDM parameters. For model, we got as result $H_{0} = 67.1\pm 4.0$ km s$^{-1}$ Mpc$^{-1}$ $\Omega _{m} 0.333 ^{+0.041}_{-0.057}$. While for found 67.2\pm 4.8$ Mpc$^{-1}$, 0.36\pm 0.16$ _{\Lambda} =0.71 ^{+0.36}_{-0.28}$. These results goes $22\%$ up $28\%$ uncertainty reduction when compared...

Abstract In this study, we used geometric distances at high redshifts (both luminosity and angular) to perform a cosmographic analysis with the Padé method, which stabilizes behaviour of series in redshift regime. However, our analyses, did not assume validity Cosmic Distance Duality Relation (CDDR), but allowed for potential violations, such as d L ( z ) = η )(1+ 2 A ), where three different functional forms are considered. By incorporating updated data from supernovae (SN), baryon acoustic...

A new accelerating cosmology driven only by baryons plus cold dark matter (CDM) is proposed in the framework of general relativity. In this model present stage Universe powered negative pressure describing gravitationally-induced particle production particles. This kind scenario has one free parameter and differential equation governing evolution scale factor exactly same $\Lambda$CDM model. For a spatially flat Universe, as predicted inflation ($\Omega_{dm}+\Omega_{baryon}=1$), it found...

Creation of cold dark matter (CCDM) can macroscopically be described by a negative pressure, and, therefore, the mechanism is capable to accelerate Universe, without need an additional energy component. In this framework, we discuss evolution perturbations considering Neo-Newtonian approach where, unlike in standard Newtonian cosmology, fluid pressure taken into account even homogeneous and isotropic background equations (Lima, Zanchin, Brandenberger, MNRAS 291, L1, 1997). The density...

We study the effect of shear and rotation on results previously obtained dealing with application spherical collapse model (SCM) to generalized Chaplygin gas (gCg)-dominated universes. The system is composed baryons gCg studied for different values parameter $\ensuremath{\alpha}$ gCg. show that joint slowing down respect simple SCM. This result utmost importance so-called unified dark matter models, since described slowdown in growth density perturbations can solve one main problems quoted...

The possibility of an expanding decelerating Universe in the distant future is investigated context a quintessence scalar field cosmology. Such conceivable evolution tested against SNe Ia and $H(z)$ cosmic chronometers data, also through model independent method based on Gaussian processes. extension exponential Ratra-Peebles (RP) quintessential cosmology whose potential now depends pair parameters ($\ensuremath{\alpha},\ensuremath{\lambda}$) predicts decelerated expansion future. Different...

We analyze the interaction between dark energy and matter from a thermodynamical perspective. By assuming they have different temperatures, we study possibility of occurring decay into energy, characterized by negative parameter $Q$. find that, if at least one fluids has nonvanishing chemical potential, for instance ${\ensuremath{\mu}}_{x}<0$ ${\ensuremath{\mu}}_{\mathrm{dm}}=0$ or ${\ensuremath{\mu}}_{x}=0$ ${\ensuremath{\mu}}_{\mathrm{dm}}>0$, is possible, where ${\ensuremath{\mu}}_{x}$...

In this work it has been developed a new approach to study the stability of system composed by an ELKO field interacting with dark matter, which could give some contribution in order alleviate cosmic coincidence problem. It is assumed that potential characterizes not specified, but related constant parameter $$\delta $$ . The strength interaction between matter and characterized $$\beta also both energy density are their pressures equations state parameters $$\omega _\phi _m$$ ,...

This paper aims to put constraints on the transition redshift $z_t$, which determines onset of cosmic acceleration, in cosmological-model independent frameworks. In order perform our analyses, we consider a flat universe and {assume} parametrization for comoving distance $D_C(z)$ up third degree $z$, second Hubble parameter $H(z)$ linear deceleration $q(z)$. For each case, show that {type Ia supernovae} data complement other {space} tighter constrains are obtained. By {combining} type...

ABSTRACT By using recent H(z) and supernovae Type Ia (SNe Ia) data, we reconstruct the evolution of kinematic parameters H(z), q(z), jerk, snap, a model-independent, non-parametric method, namely, Gaussian processes. Throughout present analysis, have allowed for spatial curvature prior, based on Planck 18 constraints. In case SNe Ia, modify python package (gapp) in order to obtain reconstruction fourth derivative function, thereby allowing us snap from comoving distances. Furthermore, method...

Abstract Scalar Fields (SF) have emerged as natural candidates for dark energy quintessential or phantom fields, they are the main ingredient of inflation theories. Instead assuming some form scalar field potential, however, this work reconstructs SF potential directly from observational data, namely, Hubble and SNe Ia data. We show that two popular forms potentials, power-law quadratic free-field, compatible with reconstructions thus obtained, at least choices priors matter density...

Abstract In this paper we study the effects of torsion space-time in expansion Universe as a candidate to dark energy. The analysis is done by reconstructing function along cosmic evolution using observational data Supernovae type Ia, Hubble parameter and Baryon Acoustic Oscillation measurements. We have used kinematic model for parameterization comoving distance parameter, then free parameters models are constrained data. reconstruction obtained directly from data, parameterizations.

Abstract The standard procedure to explain the accelerated expansion of Universe is assume existence an exotic component with negative pressure, generically called dark energy. Here, we propose a new accelerating flat cosmology without energy, driven by creation pressure reduced relativistic gas (RRG). When hybrid matter RRG identified cold matter, it describes so-called CCDM whose dynamics equivalent $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi>...

A component of dark energy has been recently proposed to explain the current acceleration Universe. Unless some unknown symmetry in Nature prevents or suppresses it, such a field may interact with pressureless matter, giving rise so-called models coupled quintessence. In this paper we propose new cosmological scenario where radiation and baryons are conserved, while is decaying into cold matter. The dilution matter particles, attenuated respect usual ${a}^{\ensuremath{-}3}$ scaling due...

Abstract A Friedmann like cosmological model in Einstein–Cartan framework is studied when the torsion function assumed to be proportional a single $$\phi (t)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>ϕ</mml:mi><mml:mo>(</mml:mo><mml:mi>t</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> coming just from spin vector contribution of ordinary matter. By analysing four different types written terms one, two and three free parameters, we found that with (t)=-...

In this paper we study a model of interacting dark energy - matter where the ratio between these components is not constant, changing from early to late times in such way that can solve or alleviate cosmic coincidence problem (CP). The interaction arises an assumed relation form $\rho_x \propto \rho_d^\alpha$, $\rho_x$ and $\rho_d$ are densities components, respectively, $\alpha$ free parameter. For equation state parameter $w=-1$ found that, if $\alpha=0$, standard $\Lambda$CDM recovered,...

ABSTRACT An approach to estimate the spatial curvature Ωk from data independently of dynamical models is suggested, through kinematic parametrizations comoving distance [DC(z)] with third-degree polynomial, Hubble parameter [H(z)] a second-degree polynomial and deceleration [q(z)] first-order polynomial. All these were done as function redshift z. We used SNe Ia set Pantheon compilation 1048 moduli estimated in range 0.01 &amp;lt; z 2.3 systematic statistical errors 31 H(z) cosmic...

ABSTRACT The Co-varying Physical Couplings (CPC) framework is a modified gravity set up assuming Einstein Field Equations wherein the quantities {G, c, Λ} are promoted to space–time functions. Bianchi identity and requirement of stress-energy tensor conservation entangle possible variations couplings Λ}, which forced co-vary as dictated by General Constraint (GC). In this paper, we explore cosmological model G, Λ functions redshift respecting GC CPC framework. We assume linear...

A new age--redshift test is proposed in order to constrain H0 on the basis of existence old high-redshift galaxies (OHRGs). In flat Λ cold dark matter model, value heavily dependent mass density parameter ΩM = 1 − ΩΛ. Such a degeneracy can be broken through joint analysis involving OHRG and baryon acoustic oscillation signature. By assuming galaxy incubation time, tinc 0.8 ± 0.4 Gyr, our yields 71 4 km s−1 Mpc−1 (1σ) with best-fit 0.27 0.03. results are good agreement independent studies...

In this work the exact Friedmann-Robertson-Walker equations for an Elko spinor field coupled to gravity in Einstein-Cartan framework are presented. The torsion functions coupling spin-connection can be exactly solved and FRW system assume a relatively simple form. limit of slowly varying there is relevant contribution acting as time cosmological model Λ(t)=Λ*+3β H2, where Λ* β constants. Observational data using distance luminosity from magnitudes supernovae constraint parameters Ωm β, which...

In this work the results from quantum process of matter creation have been used in order to constrain mass dark particles an accelerated Cold Dark Matter model (Creation Matter, CCDM). take into account a back reaction effect due particle phenomenon, it has assumed small deviation $\varepsilon$ for scale factor dominated era form $t^{\frac{2}{3}+\varepsilon}$. Based on recent $H(z)$ data, best fit values created and parameter found as $m=1.6\times10^3$ GeV, restricted 68.3\% c.l. interval ($1.5

We compile 41 H(z) data from literature and use them to constrain OΛCDM flat ΛCDM parameters. show that the available suffers uncertainties overestimation propose a Bayesian method reduce them. As result of this method, using only, we find, in context OΛCDM, H0 = 69.5 ± 2.5 km s−1 Mpc−1, Ωm 0.242 0.036, |$\Omega _\Lambda =0.68\pm 0.14$|⁠. In model, have found 70.4 1.2 Mpc−1 0.256 0.014. This corresponds an uncertainty reduction up |${\approx }30\hbox{ per cent}$| when compared uncorrected...