arXiv subjects

Javier de Cruz Perez

Publications and source records attributed to Javier de Cruz Perez.

At least 19 recordsLinked to original sources

arXiv2026

J-PAS and PFS surveys in the era of dark energy and neutrino mass measurements

Fisher-matrix forecasts are presented for the cosmological surveys of the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) and the Subaru Prime Focus Spectrograph (PFS). The wide, low-redshift coverage of J-PAS and the high-density, high-redshift mapping of PFS are strongly complementary: combining the two reduces marginalized uncertainties on all primary parameters compared with either survey individually. Adding the joint J-PAS+PFS data to next-generation CMB measurements from the Simons Observatory (SO) and \textsc{LiteBird} yields an expected precision of $σ(\sum m_ν)=0.017\,$eV in the $Λ$CDM$+\sum m_ν+N_{\rm eff}$ framework, sufficient to disfavour the inverted neutrino hierarchy at $2.34\,σ$ if the true mass sum equals the normal-ordering minimum. Motivated by recent DESI results, we also forecast within a $w_0w_a$CDM$+\sum m_ν+N_{\rm eff}$ cosmology, adopting the DESI\,DR2 best-fit values ($w_0=-0.758$, $w_a=-0.82$) as fiducial. The combination CMB+J-PAS+PFS then delivers $σ(w_0)=0.044$ and $σ(w_a)=0.18$, corresponding to a $5.1\,σ$ preference for a time-varying dark-energy equation of state. These findings show that J-PAS and PFS, especially when coupled with Stage-IV CMB observations, will provide competitive tests of neutrino physics and the dynamics of cosmic acceleration.

astro-ph.CO↗

arXiv2025

Is the $w_0w_a$CDM cosmological parameterization evidence for dark energy dynamics partially caused by the excess smoothing of Planck CMB anisotropy data?

We study the performance of the spatially-flat dynamical dark energy (DE) $w_0w_a$CDM parameterization, with redshift-dependent DE fluid equation of state parameter $w(z) = w_0 + w_a z/(1+z)$, with and without a varying CMB lensing consistency parameter $A_L$, against Planck cosmic microwave background (CMB) data (P18 and lensing) and a combination of non-CMB data composed of baryonic acoustic oscillation (BAO) measurements that do not include DESI BAO data, Pantheon+ type Ia supernovae (SNIa) observations, Hubble parameter [$H(z)$] measurements, and growth factor ($fσ_8$) data points. From our most restrictive data set, P18+lensing+non-CMB, for the $w_0w_a$CDM+$A_L$ parameterization, we obtain $w_0=-0.879\pm 0.060$, $w_a=-0.39^{+0.26}_{-0.22}$, the asymptotic limit $w(z\to\infty) = w_0+w_a=-1.27^{+0.20}_{-0.17}$, and $A_L=1.078^{+0.036}_{-0.040}$ (all $1σ$ errors). This joint analysis of CMB and non-CMB data favors DE dynamics over a cosmological constant at $\sim 1σ$ and $A_L>1$ at $\sim 2σ$, i.e. more smoothing of the Planck CMB anisotropy data than is predicted by the best-fit model. For the $w_0w_a$CDM parameterization with $A_L=1$ the evidence in favor of DE dynamics is larger, $\sim 2σ$, suggesting that at least part of the evidence for DE dynamics comes from the excess smoothing of the Planck CMB anisotropy data. For the $w_0w_a$CDM parameterization with $A_L=1$, there is a difference of $2.8σ$ between P18 and non-CMB cosmological parameter constraints and $2.7σ$ between P18+lensing and non-CMB constraints. When $A_L$ is allowed to vary these tensions reduced to $1.9σ$ and $2.1σ$ respectively. Our P18+lensing+non-CMB data compilation positively favors the $w_0w_a$CDM parameterization without and with a varying $A_L$ parameter over the flat $Λ$CDM model, and $w_0w_a$CDM+$A_L$ is also positively favored over $w_0w_a$CDM.

astro-ph.CO↗

arXiv2024

Using non-DESI data to confirm and strengthen the DESI 2024 spatially-flat $w_0w_a$CDM cosmological parameterization result

We use a combination of Planck cosmic microwave background (CMB) anisotropy data and non-CMB data that include Pantheon+ type Ia supernovae (SNIa), Hubble parameter [$H(z)$], growth factor ($fσ_8$) measurements, and a collection of baryon acoustic oscillation (BAO) data, but not recent DESI 2024 BAO measurements, to confirm the DESI 2024 (DESI+CMB+PantheonPlus) data compilation support for dynamical dark energy with an evolving equation of state parameter $w(z) = w_0 + w_a z/(1+z)$. From our joint compilation of CMB and non-CMB data, in a spatially-flat cosmological model, we obtain $w_0 = -0.850 \pm 0.059$ and $w_a = -0.59^{+0.26}_{-0.22}$ and find that this dynamical dark energy is favored over a cosmological constant by $\sim 2σ$. Our data constraints on the flat $w_0w_a$CDM parameterization are slightly more restrictive than the DESI 2024 constraints, with the DESI 2024 and our values of $w_0$ and $w_a$ differing by $-0.27σ$ and $0.44σ$, respectively. Our data compilation slightly more strongly favors the flat $w_0w_a$CDM model over the flat $Λ$CDM model than does the DESI 2024 data compilation. We note that our CMB and non-CMB data $w_0w_a$CDM parameterization cosmological constraints are discrepant at 2.7$σ$, a little larger than the 1.9$σ$ discrepancy between DESI DR1 BAO and CMB data flat $Λ$CDM model cosmological constraints. We also show that if we remove the Pantheon+ SNIa contribution from the non-CMB data, for the $w_0w_a$CDM parameterization we still find tension between P18 and non-CMB data (2.5$σ$) and P18+lensing and non-CMB data (2.4$σ$). Even after the exclusion of Pantheon+ SNIa data the $Λ$CDM model is still disfavoured at $\sim 2σ$ c.l.

astro-ph.CO↗

arXiv2024

Updated observational constraints on spatially-flat and non-flat $Λ$CDM and XCDM cosmological models

We study 6 LCDM models, with 4 allowing for non-flat geometry and 3 allowing for a non-unity lensing consistency parameter $A_L$. We also study 6 XCDM models with a dynamical dark energy density X-fluid with equation of state $w$. For the non-flat models we use two different primordial power spectra, Planck $P(q)$ and new $P(q)$. These models are tested against: Planck 2018 CMB power spectra (P18) and lensing potential power spectrum (lensing), and an updated compilation of BAO, SNIa, $H(z)$, and $fσ_8$ data [non-CMB data]. P18 data favor closed geometry for the LCDM and XCDM models and $w<-1$ (phantom-like dark energy) for the XCDM models while non-CMB data favor open geometry for the LCDM models and closed geometry and $w>-1$ (quintessence-like dark energy) for the XCDM models. When P18 and non-CMB data are jointly analyzed there is weak evidence for open geometry and moderate evidence for quintessence-like dark energy. Regardless of data used, $A_L>1$ is always favored. The XCDM model constraints obtained from CMB data and from non-CMB data are incompatible, ruling out the 3 $A_L = 1$ XCDM models at $> 3σ$. In the 9 models not ruled out, for the P18+lensing+non-CMB data set we find little deviation from flat geometry and moderate deviation from $w=-1$. In all 6 non-flat models (not ruled out), open geometry is mildly favored, and in all 3 XCDM+$A_L$ models (not ruled out) quintessence-like dark energy is moderately favored (by at most $1.6 σ$). In the $A_L = 1$ non-flat LCDM cases, we find for P18+lensing+non-CMB data $Ω_k = 0.0009 \pm 0.0017$ [$0.0008 \pm 0.0017$] for the Planck [new] $P(q)$ model, favoring open geometry. The flat LCDM model remains the simplest (largely) observationally-consistent cosmological model. Our cosmological parameter constraints obtained for the flat LCDM model (and other models) are the most restrictive results to date (Abridged).

astro-ph.CO↗

arXiv2023

Running vacuum in Brans-Dicke theory: a possible cure for the $σ_8$ and $H_0$ tensions

Extensions of the gravitational framework of Brans-Dicke (BD) are studied by considering two different scenarios: i) `BD-$Λ$CDM', in which a rigid cosmological constant, $Λ$, is included, thus constituting a BD version of the vanilla concordance $Λ$CDM model (the current standard model of cosmology with flat three-dimensional geometry), and ii) `BD-RVM', a generalization of i) in which the vacuum energy density (VED), $ρ_{\textrm{vac}}$, is a running quantity evolving with the square of the Hubble rate: $δρ_{\textrm{vac}}(H)\propto ν\, m^2_{\textrm{Pl}} (H^2-H_0^2)$ (with $|ν|\ll 1$). This dynamical scenario is motivated by recent studies of quantum field theory (QFT) in curved spacetime, which lead to the running vacuum model (RVM). We solve the background as well as the perturbation equations for each cosmological model and test their performance against the modern wealth of cosmological data, namely a compilation of the latest SNIa+$H(z)$+BAO+LSS+CMB observations. We utilize the AIC and DIC statistical information criteria in order to determine if they can fit better the observations than the concordance model. The two BD extensions are tested by considering three different datasets. According to the AIC and DIC criteria, both BD extensions i) and ii) are competitive, but the second one (the BD-RVM scenario) is particularly favored when it is compared with the vanilla model. This fact may indicate that the current observations favor a mild dynamical evolution of the Newtonian coupling $G_N$ as well as of the VED. This is in agreement with recent studies suggesting that the combination of these two features can be favorable for a possible resolution of the $σ_8$ and $H_0$ tensions. In this work, we show that the Brans-Dicke theory with running vacuum has the potential to alleviate the two tensions at the same time.

astro-ph.CO↗

arXiv2023

Running vacuum in the Universe: phenomenological status in light of the latest observations, and its impact on the $σ_8$ and $H_0$ tensions

A substantial body of phenomenological and theoretical work over the last few years strengthens the possibility that the vacuum energy density (VED) of the universe is dynamical, and in particular that it adopts the `running vacuum model' (RVM) form, in which the VED evolves mildly as $δρ_{\rm vac}(H)\sim ν_{\rm eff} m_{\rm Pl}^2{\cal O}\left(H^2\right)$, where $H$ is the Hubble rate and $ν_{\rm eff}$ is a (small) free parameter. This dynamical scenario is grounded on recent studies of quantum field theory (QFT) in curved spacetime and also on string theory. It turns out that what we call the `cosmological constant', $Λ$, is no longer a rigid parameter but the nearly sustained value of $8πG(H)ρ_{\rm vac}(H)$ around (any) given epoch $H(t)$, where $G(H)$ is the gravitational coupling, which can also be very mildly running (logarithmically). Of particular interest is the possibility suggested in past works that such a running may help to cure the cosmological tensions afflicting the $Λ$CDM. In the current study, we reanalyze it in full and we find it becomes further buttressed. Using the modern cosmological data, namely a compilation of the latest $SNIa+BAO+$H(z)$+LSS+CMB$ observations, we probe to which extent the RVM provides a quality fit better than the concordance $Λ$CDM model, paying particular emphasis on its impact on the $σ_8$ and $H_0$ tensions. We utilize the Einstein-Boltzmann system solver $CLASS$ and the Monte Carlo sampler $MontePython$ for the statistical analysis, as well as the statistical $DIC$ criterion to compare the running vacuum against the rigid vacuum ($ν_{\rm eff} = 0$). We show that with a tiny amount of vacuum dynamics ($|ν_{\rm eff}|\ll 1$) the global fit can improve significantly with respect to the $Λ$CDM and the mentioned tensions may subside to inconspicuous levels.

astro-ph.CO↗

arXiv2023

Current data are consistent with flat spatial hypersurfaces in the $Λ$CDM cosmological model but favor more lensing than the model predicts

We study the performance of three pairs of tilted $Λ$CDM cosmological models, two pairs allowing for non-flat spatial hypersurfaces with CMB temperature and polarization power spectrum data (P18) from Planck, P18 lensing (lensing), and non-CMB data (non-CMB). For the six models, we measure cosmological parameters and study whether or not pairs of the data sets are mutually consistent in these models. Half of these models allow the lensing consistency parameter $A_L$ to be an additional free parameter, while the other three have $A_L = 1$. The tilted spatially-flat models assume the usual primordial spatial inhomogeneity power spectrum. The tilted non-flat models assume either the primordial power spectrum used in the Planck group analyses [Planck $P(q)$] or a recently computed power spectrum [new $P(q)$]. In the tilted non-flat models with $A_L=1$ we find differences between P18 data and non-CMB data cosmological parameter constraints, which are large enough to rule out the Planck $P(q)$ model at 3$σ$ but not the new $P(q)$ model. While both P18 data and non-CMB data separately favor a closed geometry when P18+non-CMB data are jointly analyzed the evidence in favor of non-flat hypersurfaces subsides. Differences between P18 data and non-CMB data cosmological constraints subside when $A_L$ is allowed to vary. From the most restrictive P18+lensing+non-CMB data combination we get almost model-independent constraints and find that the $A_L>1$ option is preferred over the $Ω_k<0$ one, with the $A_L$ parameter, for all models, being larger than unity by $\sim 2.5σ$. According to the deviance information criterion, in the P18+lensing+non-CMB analysis, the varying $A_L$ option is on the verge of being strongly favored over the $A_L=1$ one, which could indicate a problem for the standard tilted flat $Λ$CDM model (Abridged abstract).

astro-ph.CO↗

arXiv2021

BD-$Λ$CDM and Running Vacuum Models: Theoretical background and current observational status

We present an analysis of the Brans-Dicke cosmological model with a cosmological constant and cold dark matter (BD-$Λ$CDM). We find that the BD-$Λ$CDM is favored by the overall cosmological data (SNIa+BAO+$H(z)$+LSS+CMB) when it is compared with the standard model of cosmology. The BD-$Λ$CDM model can be viewed from the GR perspective as a Running Vacuum Model (RVM) with a time evolving vacuum energy density. Due to this fact and also to its time evolving effective gravitational coupling, the model can alleviate the $σ_8$ and the $H_0$ tensions at a time. We also present the results for different types of RVM's when they are tested in the light of the cosmological data and we show that a mild dynamics for the vacuum energy density can help to smooth out the aforementioned tensions, thus improving the performance of $Λ$CDM model.

astro-ph.CO↗

arXiv2021

Running vacuum against the $H_0$ and $σ_8$ tensions

The cosmological term, $Λ$, was introduced $104$ years ago by Einstein in his gravitational field equations. Whether $Λ$ is a rigid quantity or a dynamical variable in cosmology has been a matter of debate for many years, especially after the introduction of the general notion of dark energy (DE). $Λ$ is associated to the vacuum energy density, $ρ_{\rm vac}$, and one may expect that it evolves slowly with the cosmological expansion. Herein we present a devoted study testing this possibility using the promising class of running vacuum models (RVM's). We use a large string $SNIa+BAO+H(z)+LSS+CMB$ of modern cosmological data, in which for the first time the CMB part involves the full Planck 2018 likelihood for these models. We test the dependence of the results on the threshold redshift $z_*$ at which the vacuum dynamics is activated in the recent past and find positive signals up to $\sim4.0σ$ for $z_*\simeq 1$. The RVM's prove very competitive against the standard $Λ$CDM model and give a handle for solving the $σ_8$ tension and alleviating the $H_0$ one.

astro-ph.CO↗

arXiv2020

Brans-Dicke cosmology with a $Λ$- term: a possible solution to $Λ$CDM tensions

We present a full-fledged analysis of Brans-Dicke cosmology with a cosmological constant and cold dark matter (BD-$Λ$CDM for short). We extend the scenarios where the current cosmological value of the BD-field is restricted by the local astrophysical domain to scenarios where that value is fixed only by the cosmological observations, which should be more natural in view of the possible existence of local screening mechanims. Our analysis includes both the background and perturbations equations in different gauges. We find that the BD-$Λ$CDM is favored by the overall cosmological data as compared to the concordance GR-$Λ$CDM model, namely data on distant supernovae, cosmic chronometers, local measurements of the Hubble parameter, baryonic acoustic oscillations, Large-Scale Structure formation and the cosmic microwave background under full Planck 2018 CMB likelihood. We also test the impact of Strong and Weak-Lensing data on our results, which can be significant. We find that the BD-$Λ$CDM can mimic effective quintessence with a significance of about $3-3.5σ$ c.l. (depending on the lensing datasets). The fact that the BD-$Λ$CDM behaves effectively as a Running Vacuum Model (RVM) when viewed from the GR perspective helps to alleviate some of the existing tensions with the data, such as the $σ_8$ excess predicted by GR-$Λ$CDM. On the other hand, the BD-$Λ$CDM model has a crucial bearing on the acute $H_0$-tension with the local measurements, which is rendered virtually harmless owing to the small increase of the effective value of the gravitational constant with the expansion. The simultaneous alleviation of the two tensions is a most remarkable feature of BD-gravity with a cosmological constant in the light of the current observations, and hence goes in support of BD-$Λ$CDM against GR-$Λ$CDM

astro-ph.CO↗

arXiv2019

Brans-Dicke gravity with a cosmological constant smoothes out $Λ$CDM tensions

We analyze Brans-Dicke gravity with a cosmological constant, $Λ$, and cold dark matter (BD-$Λ$CDM for short) in the light of the latest cosmological observations on distant supernovae, Hubble rate measurements at different redshifts, baryonic acoustic oscillations, large scale structure formation data, gravitational weak-lensing and the cosmic microwave background under full Planck 2015 CMB likelihood. Our analysis includes both the background and perturbations equations. We find that BD-$Λ$CDM is observationally favored as compared to the concordance $Λ$CDM model, which is traditionally defined within General Relativity (GR). In particular, some well-known persisting tensions of the $Λ$CDM with the data, such as the excess in the mass fluctuation amplitude $σ_8$ and specially the acute $H_0$-tension with the local measurements, essentially disappear in this context. Furthermore, viewed from the GR standpoint, BD-$Λ$CDM cosmology mimics quintessence at $\gtrsim3σ$ c.l. near our time.

astro-ph.CO↗

arXiv2019

Signs of Dynamical Dark Energy in Current Observations

Investigations on dark energy (DE) are currently inconclusive about its time evolution. Hints of this possibility do however glow now and then in the horizon. Herein we assess the current status of dynamical dark energy (DDE) in the light of a large body of updated $SNIa+H(z)+BAO+LSS+CMB$ observations, using the full Planck 2015 CMB likelihood. The performance of the $Λ$CDM model (with equation of state $w=-1$ for $Λ$) is confronted with that of the general XCDM and CPL parametrizations, as well as with the traditional $Φ$CDM model based on the scalar field potential $V\sim Φ^{-α}$. In particular, we gauge the impact of the bispectrum in the LSS and BAO parts, and show that the subset of $CMB+BAO+LSS$ observations may contain the bulk of the DDE signal. The departure from $w=-1$ is significant: roughly $2.6σ$ for XCDM and $2.9σ$ for $Φ$CDM. In both cases the full Bayesian evidence is found to be positive even for a prior range of the DDE parameters extending over several standard deviations from the mean when the bispectrum is taken into account. Positive signs follow as well from the preliminary results of Planck 2018 data using the compressed CMB likelihood. As a bonus we also find that the $σ_8$-tension becomes reduced with DDE.

astro-ph.CO↗

arXiv2018

Brans-Dicke cosmology mimicking running vacuum

Brans-Dicke (BD) cosmology is reconsidered from an approach in which the model can be formulated in $Λ$CDM form, but at the expense of replacing the rigid cosmological constant $Λ$ with a dynamical quasivacuum component which depends on a small parameter $ε$. The product of $ε$ times the BD-parameter $ω_{\rm BD}$ becomes exactly determined in terms of the ordinary cosmological parameters. The GR limit is recovered for $ω_{\rm BD}\to\infty$ when $ε\to 0$. We solve the background cosmology of the model as well as the perturbations equations. When fitted to the cosmological data, we find that the BD-cosmology, transcribed in such an effective GR form, appears to be competitive with the $Λ$CDM and emulates the running vacuum model.

gr-qc↗

arXiv2018

Possible signals of vacuum dynamics in the Universe

We study a generic class of time-evolving vacuum models which can provide a better phenomenological account of the overall cosmological observations as compared to the $Λ$CDM. Among these models, the running vacuum model (RVM) appears to be the most motivated and favored one, at a confidence level of $\sim 3σ$. We further support these results by computing the Akaike and Bayesian information criteria. Our analysis also shows that we can extract fair signals of dynamical dark energy (DDE) by confronting the same set of data to the generic XCDM and CPL parametrizations. In all cases we confirm that the combined triad of modern observations on Baryonic Acoustic Oscillations, Large Scale Structure formation, and the Cosmic Microwave Background, provide the bulk of the signal sustaining a possible vacuum dynamics. In the absence of any of these three crucial data sources, the DDE signal can not be perceived at a significant confidence level. Its possible existence could be a cure for some of the tensions existing in the $Λ$CDM when confronted to observations.

astro-ph.CO↗

arXiv2018

Dynamical dark energy versus $Λ=$const. in light of observations

After about two decades of the first observational papers confirming the accelerated expansion of the universe, we are still facing the question whether the cause of it is a rigid cosmological constant $Λ$-term or a mildly evolving dynamical dark energy (DDE). While studies focusing mainly on CMB measurements do not perceive signs of physics beyond the $Λ$CDM, in this work we show that if we take a large string $SNIa+BAO+H(z)+LSS+CMB$ of modern cosmological observations, in which not only the CMB but also a rich sample of large scale structure formation data are included, one can extract $\sim 3.3σ$ signs of DDE using a simple XCDM parameterization. These signs can be enhanced up to near $3.8σ$ in the context of the running vacuum model (RVM), in which the vacuum energy density is in interaction with dark matter. Recently the RVM has been shown to provide an efficient and economical solution to the $σ_8$-tension, which is one of the intriguing phenomenological problems that has not been possible to solve within the $Λ$CDM so far. This fact contributes to strengthen the possibility that dynamical vacuum energy, or in general DDE, could be presently favored by the observations.

gr-qc↗

arXiv2017

The $H_0$ tension in light of vacuum dynamics in the Universe

Despite the outstanding achievements of modern cosmology, the classical dispute on the precise value of $H_0$, which is the first ever parameter of modern cosmology and one of the prime parameters in the field, still goes on and on after over half a century of measurements. Recently the dispute came to the spotlight with renewed strength owing to the significant tension (at $>3σ$ c.l.) between the latest Planck determination obtained from the CMB anisotropies and the local (distance ladder) measurement from the Hubble Space Telescope (HST), based on Cepheids. In this work, we investigate the impact of the running vacuum model (RVM) and related models on such a controversy. For the RVM, the vacuum energy density $ρ_Λ$ carries a mild dependence on the cosmic expansion rate, i.e. $ρ_Λ(H)$, which allows to ameliorate the fit quality to the overall $SNIa+BAO+H(z)+LSS+CMB$ cosmological observations as compared to the concordance $Λ$CDM model. By letting the RVM to deviate from the vacuum option, the equation of state $w=-1$ continues to be favored by the overall fit. Vacuum dynamics also predicts the following: i) the CMB range of values for $H_0$ is more favored than the local ones, and ii) smaller values for $σ_8(0)$. As a result, a better account for the LSS structure formation data is achieved as compared to the $Λ$CDM, which is based on a rigid (i.e. non-dynamical) $Λ$ term.

astro-ph.CO↗

arXiv2017

Vacuum dynamics in the Universe versus a rigid $Λ=$const

In this year, in which we celebrate 100 years of the cosmological term, $Λ$, in Einstein's gravitational field equations, we are still facing the crucial question whether $Λ$ is truly a fundamental constant or a mildly evolving dynamical variable. After many theoretical attempts to understand the meaning of $Λ$, and in view of the enhanced accuracy of the cosmological observations, it seems now mandatory that this issue should be first settled empirically before further theoretical speculations on its ultimate nature. In this work, we summarize the situation of some of these studies. Devoted analyses made recently show that the $Λ=$const. hypothesis, despite being the simplest, may well not be the most favored one. The overall fit to the cosmological observables $SNIa+BAO+H(z)+LSS+CMB$ singles out the class RVM of the "running" vacuum models, in which $Λ=Λ(H)$ is an affine power-law function of the Hubble rate. It turns out that the performance of the RVM as compared to the "concordance" $Λ$CDM model (with $Λ=$const.) is much better. The evidence in support of the RVM may reach $\sim 4σ$ c.l., and is bolstered with Akaike and Bayesian criteria providing strong evidence in favor of the RVM option. We also address the implications of this framework on the tension between the CMB and local measurements of the current Hubble parameter.

astro-ph.CO↗

arXiv2017

Dynamical dark energy: scalar fields and running vacuum

Recent analyses in the literature suggest that the concordance $Λ$CDM model with rigid cosmological term, $Λ=$const., may not be the best description of the cosmic acceleration. The class of "running vacuum models", in which $Λ=Λ(H)$ evolves with the Hubble rate, has been shown to fit the string of $SNIa+BAO+H(z)+LSS+CMB$ data significantly better than the $Λ$CDM. Here we provide further evidence on the time-evolving nature of the dark energy (DE) by fitting the same cosmological data in terms of scalar fields. As a representative model we use the original Peebles & Ratra potential, $V\proptoΦ^{-α}$. We find clear signs of dynamical DE at $\sim 4σ$ c.l., thus reconfirming through a nontrivial scalar field approach the strong hints formerly found with other models and parametrizations.

astro-ph.CO↗