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The Cosmic Distance Duality Relation (CDDR) defines a fundamental link in modern cosmology between geometric distance measurements and redshift. Any observed deviations from the CDDR could suggest the need for new physics beyond the $\Lambda$CDM model. In this study, we model geometric distances (both luminosity and angular) using a cosmographic expansion with the Pade method, which stabilizes the behavior of the cosmographic series at high redshifts. This approach allows us to determine geometric distances independently of any specific model. By incorporating updated data from supernovae (SN), baryon acoustic oscillations (BAO), and cosmic chronometers (CC), we obtain observational constraints for parametric models that quantify the CDDR, alongside all baseline cosmographic parameters. We find that potential CDDR violations introduce new statistical correlations in the cosmographic parameters ($H_0$, $q_0$, and $j_0$). However, within this framework, we do not observe significant deviations from the CDDR, and our results remain consistent with the predictions of the $\Lambda$CDM model. This work offers a novel and straightforward method for testing the CDDR by fixing background evolution through cosmographic techniques, thereby paving the way for new geometric observational tests of possible deviations from standard cosmology., Comment: 9 pages, 5 figures

In recent years, Cosmic Microwave Background (CMB) observations, Weak Lensing surveys, and $f(z)\sigma_8(z)$ measurements from Redshift-Space Distortions (RSD) have revealed a significant ($\sim$3$-$5$\sigma$) discrepancy in the inferred value of the matter clustering parameter $S_8$. In this work, we investigate the implications of RSD for a cosmological framework postulating an interaction between Dark Energy (DE) and Dark Matter (DM). We explore scenarios where DM can transfer energy-momentum to DE or vice versa. The energy-momentum flow is characterized by the strength and the sign of the coupling parameter $\xi$. Our baseline analysis combines RSD measurements with the latest data from Baryon Acoustic Oscillations (BAO) observed by DESI, Type Ia Supernovae from the PantheonPlus sample, and CMB data from Planck. We demonstrate that RSD measurements provide significant additional information. When energy-momentum flows from DM to DE (i.e., $\xi < 0$), these measurements set stringent new bounds on the interaction strength. Conversely, when energy-momentum flows from DE to DM ($\xi > 0$), they favor interactions at more than the $2\sigma$ confidence level. Models with $\xi > 0$ can effectively resolve the tension in $S_8$, presenting them as compelling alternatives., Comment: 13 pages, 6 figures. Comments welcome and appreciated

In this study, we investigate deviations from the Planck-$\Lambda$CDM model in the late universe ($z \lesssim 2.5$) using the Gaussian Processes method, with minimal assumptions. Our goal is to understand where exploring new physics in the late universe is most relevant. We analyze recent Cosmic Chronometers (CC), Type Ia Supernovae (SN), and Baryon Acoustic Oscillations (BAO) data. By examining reconstructions of the dimensionless parameter $\delta(z)$, which measures deviations of the Hubble parameter from the Planck-$\Lambda$CDM predictions, we identify intriguing features at low ($z \lesssim 0.5$) and high ($z \gtrsim 2$) redshifts. Deviations from the Planck-$\Lambda$CDM model were not significant between $0.5\lesssim z \lesssim2$. Using the combined CC+SN+BAO dataset, we gain insights into dark energy (DE) dynamics, resembling characteristics of omnipotent DE, extending beyond quintessence and phantom models. DE exhibits n-quintessence traits for $z\gtrsim2$, transitioning with a singularity around $z\sim2$ to usual phantom traits in $1\lesssim z\lesssim2$. DE characteristics differ between scenarios ($H_0$-SH0ES and $H_0$-$\Lambda$\&CMB), with $H_0$-SH0ES leaning towards phantom traits and $H_0$-$\Lambda$\&CMB towards quintessence. We suggest exploring new physics at $z\lesssim0.5$ and $1.5\lesssim z\lesssim2.5$, particularly around $z = 2$, to understand cosmological tensions such as $H_0$ and $S_8$., Comment: 15 pages, 11 figures. Accepted for publication in EPJC

The idea of a rapid sign-switching cosmological constant (mirror AdS-dS transition) in the late universe at $z\sim1.7$, known as the $\Lambda_{\rm s}$CDM model, has significantly improved the fit to observational data and provides a promising scenario for alleviating major cosmological tensions, such as the $H_0$ and $S_8$ tensions. However, in the absence of a fully predictive model, implementing this fit required conjecturing that the dynamics of the linear perturbations are governed by general relativity. Recent work embedding the $\Lambda_{\rm s}$CDM model with the Lagrangian of a type-II minimally modified gravity known as VCDM has propelled $\Lambda_{\rm s}$CDM to a fully predictive model, removing the uncertainty related to the aforementioned assumption; we call this new model $\Lambda_{\rm s}$VCDM. In this work, we demonstrate that not only does $\Lambda_{\rm s}$CDM fit the data better than the standard $\Lambda$CDM model, but the new model, $\Lambda_{\rm s}$VCDM, performs even better in alleviating cosmological tensions while also providing a better fit to the data, including CMB, BAO, SNe Ia, and Cosmic Shear measurements. Our findings highlight the $\Lambda_{\rm s}$CDM framework, particularly the $\Lambda_{\rm s}$VCDM model, as a compelling alternative to the standard $\Lambda$CDM model, especially by successfully alleviating the $H_0$ tension. Additionally, these models predict higher values for $\sigma_8$, indicating enhanced structuring, albeit with lower present-day matter density parameter values and consequently reduced $S_8$ values, alleviating the $S_8$ tension as well. This demonstrates that the data are well fit by a combination of background and linear perturbations, both having dynamics differing from those of $\Lambda$CDM. This paves the way for further exploration of new ways for embedding the sign-switching cosmological constant into other models., Comment: 15 pages, 5 figures, 2 tables

In this work, we obtain Hubble constant ($H_0$) estimates by using two galaxy cluster gas mass fraction measurement samples, Type Ia supernovae luminosity distances, and the validity of the cosmic distance duality relation. Notably, the angular diameter distance (ADD) to each galaxy cluster in the samples is determined by combining its gas mass fraction measurement with galaxy clustering observations, more precisely, the $\Omega_b/\Omega_m$ ratio. Such a combination results in a $H_0$ estimate that is independent of a specific cosmological framework. In one of the samples, the gas fraction measurements were calculated in spherical shells at radii near $r_{\rm 2500}$ (44 data points), while in the other (103 data points) the measurements were calculated within $ r_{\rm 500}$. We find $H_0=72.7^{+6.3}_{-5.6}$ km/s/Mpc at 68\% CL for the joint analysis of these data sets. We also investigate the impact on the $H_0$ determination by exploring the precision and number of gas mass fraction data by performing a data Monte Carlo simulation. Our simulations show that future measurements could achieve a precision of up to 5\% for $H_0$., Comment: 9 pages, 5 figures. H0 estimate updated with joint analysis of the two gas mass fraction samples

We investigate the implications of the Baryon Acoustic Oscillation measurements released by the Dark Energy Spectroscopic Instrument (DESI) for Interacting Dark Energy (IDE) models characterized by an energy-momentum flow from Dark Matter to Dark Energy. By combining Planck-2018 and DESI data, we observe a preference for interactions exceeding the 95% confidence level, yielding a present-day expansion rate $H_0=71.4\pm1.5$ km/s/Mpc, in agreement with SH0ES. This preference remains robust when including measurements of the expansion rate $H(z)$ obtained from the relative ages of massive, early-time, and passively-evolving galaxies, as well as when considering distance moduli measurements from Type-Ia Supernovae sourced from the Pantheon-plus catalog using the SH0ES Cepheid host distances as calibrators. Overall, high and low redshift data can be equally or better explained within the IDE framework compared to $\Lambda$CDM, while also yielding higher values of $H_0$ in better agreement with the local distance ladder estimate., Comment: 6 pages, 3 figures

We present a comprehensive reassessment of the state of Interacting Dark Energy (IDE) cosmology, namely models featuring a non-gravitational interaction between Dark Matter (DM) and Dark Energy (DE). To achieve high generality, we extend the dark sector physics by considering two different scenarios: a non-dynamical DE equation of state $w_0\neq-1$, and a dynamical $w(a)=w_0+w_a(1-a)$. In both cases, we distinguish two different physical regimes resulting from a phantom or quintessence equation of state. To circumvent early-time superhorizon instabilities, the energy-momentum transfer should occur in opposing directions within the two regimes, resulting in distinct phenomenological outcomes. We study quintessence and phantom non-dynamical and dynamical models in light of two independent Cosmic Microwave Background (CMB) experiments - the Planck satellite and the Atacama Cosmology Telescope. We analyze CMB data both independently and in combination with Supernovae (SN) distance moduli measurements from the Pantheon-Plus catalog and Baryon Acoustic Oscillations (BAO) from the SDSS-IV eBOSS survey. Our results update and extend the state-of-the-art analyses, significantly narrowing the parameter space allowed for these models and limiting their overall ability to reconcile cosmological tensions. Although considering different combinations of data leaves some freedom to increase $H_0$ towards the value measured by the SH0ES collaboration, our most constraining dataset (CMB+BAO+SN) indicates that fully reconciling the tension solely within the framework of IDE remains challenging., Comment: 21 pages, 4 figures, 9 tables. V2: additional references added, clarified some aspects of the results, their interpretation, and implications. Version accepted for publication in PRD

The Baryon Acoustic Oscillations (BAO) phenomenon provides a unique opportunity to establish a standard ruler at any epoch in the history of the evolving universe. The key lies in identifying a suitable cosmological tracer to conduct the measurement. In this study, we focus on quantifying the sound horizon scale of BAO in the Local Universe. Our chosen cosmological tracer is a sample of blue galaxies from the SDSS survey, positioned at the effective redshift $z_{{\eff}} = 0.166$. Utilizing Planck-CMB input values for redshift-to-distance conversion, we derive the BAO scale $s_{\scalebox{0.65}{\rm BAO}} = 100.28 ^{+10.79} _{-22.96}$ Mpc$/h$ at the 1$\sigma$ confidence level. Subsequently, we extrapolate the BAO signal scale in redshift space: $\Delta z_{\scalebox{0.6}{\rm BAO}}(z_{\rm eff}=0.166)=0.0361^{+0.00262}_ {-0.0055}$. This measurement holds the potential to discriminate among dark energy models within the Local Universe. To validate the robustness of our methodology for BAO scale measurement, we conduct three additional BAO analyses using different cosmographic approaches for distance calculation from redshifts. These tests aim to identify possible biases or systematics in our measurements of $s_{\scalebox{0.65}{\rm BAO}}$. Encouragingly, our diverse cosmographic approaches yield results in statistical agreement with the primary measurement, indicating no significant deviations. Conclusively, our study contributes with a novel determination of the BAO scale in the Local Universe, at $z_{{\eff}} = 0.166$, achieved through the analysis of the SDSS blue galaxies cosmic tracer., Comment: Accepted for publication in MNRAS

Understanding the behavior of the matter power spectrum on non-linear scales beyond the $\Lambda$CDM model is crucial for accurately predicting the large-scale structure (LSS) of the Universe in non-standard cosmologies. In this work, we present an analysis of the non-linear matter power spectrum within the framework of interacting dark energy-dark matter cosmologies (IDE). We employ N-body simulations and theoretical models to investigate the impact of IDE on these non-linear scales. Beginning with N-body simulations characterized by a fixed parameter space delineated by prior observational research, we adeptly fit the simulated spectra with a simple parametric function, achieving accuracy within 5\%. Subsequently, we refine a modified halo model tailored to the IDE cosmology, exhibiting exceptional precision in fitting the simulations down to scales of approximately 1 h/Mpc. To assess the model's robustness, we conduct a forecast analysis for the Euclid survey, employing our refined model. We find that the coupling parameter $\xi$ will be constrained to $\sigma(\xi) = 0.0046$. This marks a significant improvement by an order of magnitude compared to any other current observational tests documented in the literature. These primary findings pave the way for a novel preliminary approach, enabling the utilization of IDE models for observational constraints concerning LSS data on non-linear scales., Comment: 14 pages, 6 figures and 1 table

The Kerr spacetime is a fundamental solution of general relativity (GR), describing the gravitational field around a rotating, uncharged black hole (BH). Kerr spacetime has been crucial in modern astrophysics and it serves as a foundation for the study of gravitational waves (GWs). Possible deviations in Kerr geometry may indicate deviations from GR predictions. In this work, we consider the Johannsen-Psaltis metric, which is a beyond-Kerr metric characterized by a single free parameter, and then we probe this theory framework using several GWs observations from the third Gravitational-wave Transient Catalog (GWTC-3). We find that, for most of the events analyzed, there are no significant deviations from the null hypothesis, i.e. the Kerr metric. Our main findings demonstrate alignment and certain enhancements when compared to previous estimates documented in the literature., Comment: 8 pages, 4 figures

This paper simplifies the induced four-dimensional gravitational equations originating from a five-dimensional bulk within the framework of Nash's embeddings, incorporating them into a well-known $\mu-\Sigma$ modified gravity (MG) parametrization. By leveraging data from Planck Public Release 4 (PR4), BICEP/Keck Array 2018, Planck cosmic microwave background lensing, and baryon acoustic oscillation observations, we establish a stringent lower limit for the tensor-to-scalar ratio parameter: $r < 0.0303$ at a confidence level (CL) of 95\%. This finding suggests the presence of extrinsic dynamics influencing standard four-dimensional cosmology. Notably, this limit surpasses those typically obtained through Bayesian analysis using Markov Chain Monte Carlo (MCMC) techniques, which yield $r<0.038$, or through the frequentist profile likelihood method, which yields $r<0.037$ at 95\% CL., Comment: 14 pages, 3 figures, accepted version in PRD

We investigated a possible interaction between cold dark matter and dark energy, corresponding to a well-known interacting dark energy model discussed in the literature within the context of resolving the Hubble tension. We put constraints on it in a novel way, by creating new likelihoods with an analytical marginalization over the Hubble parameter $H_0$, the sound horizon $r_d$, and the supernova absolute magnitude $M_B$. Our aim is to investigate the impacts on the coupling parameter of the interacting model, $\xi$, and the equation of state of dark energy $w$ and the matter density parameter $\Omega_{m,0}$. The late-time cosmological probes used in our analysis include the PantheonPlus (calibrated and uncalibrated), cosmic chronometers, and baryon acoustic oscillation samples and the Pantheon for comparison. Through various combinations of these datasets, we demonstrate hints of an up to $2\sigma$ deviation from the standard $\Lambda$ cold dark matter model., Comment: published in Astronomy & Astrophysics

We have successfully integrated $\Lambda_{\rm s}$CDM, a promising model for alleviating cosmological tensions, into a theoretical framework by endowing it with a specific Lagrangian from the VCDM model, a type-II minimally modified gravity. In this theory, we demonstrate that an auxiliary scalar field with a linear potential induces an effective cosmological constant, enabling the realization of an abrupt mirror AdS-dS transition in the late universe through a piecewise linear potential. To eliminate the sudden singularity in this setup and ensure stable transitions, we smooth out this potential. Realized within the VCDM theory, the $\Lambda_{\rm s}$CDM model facilitates two types of rapid smooth mirror AdS-dS transitions: (i) the agitated transition, associated with a smooth jump in the potential, where $\Lambda_{\rm s}$, and consequently $H$, exhibits a bump around the transition's midpoint; and (ii) the quiescent transition, associated with a smooth change in the slope of the potential, where $\Lambda_{\rm s}$ transitions gracefully. These transitions are likely to leave distinct imprints on the background and perturbation dynamics, potentially allowing the observational data to distinguish between them. This novel theoretical framework propels $\Lambda_{\rm s}$CDM into a fully predictive model capable of exploring the evolution of the Universe including the late-time AdS-dS transition epoch, and extends the applicability of the model. We believe further research is crucial in establishing $\Lambda_{\rm s}$CDM as a leading candidate or guide for a new concordance cosmological model., Comment: 9 pages (including appendices), 4 figures, and no tables

The very first light captured by the James Webb Space Telescope (JWST) revealed a population of galaxies at very high redshifts more massive than expected in the canonical $\Lambda$CDM model of structure formation. Barring, among others, a systematic origin of the issue, in this paper, we test alternative cosmological perturbation histories. We argue that models with a larger matter component $\Omega_m$ and/or a larger scalar spectral index $n_s$ can substantially improve the fit to JWST measurements. In this regard, phenomenological extensions related to the dark energy sector of the theory are appealing alternatives, with Early Dark Energy emerging as an excellent candidate to explain (at least in part) the unexpected JWST preference for larger stellar mass densities. Conversely, Interacting Dark Energy models, despite producing higher values of matter clustering parameters such as $\sigma_8$, are generally disfavored by JWST measurements. This is due to the energy-momentum flow from the dark matter to the dark energy sector, implying a smaller matter energy density. Upcoming observations may either strengthen the evidence or falsify some of these appealing phenomenological alternatives to the simplest $\Lambda$CDM picture., Comment: 35 pages, 6 figures, 8 tables. V2: New independent JWST datasets included in the analysis; clarified some points on the analysis methodology; clarified some results; additional references added. Version accepted for publication in JCAP

Alternative cosmological models have been proposed to alleviate the tensions reported in the concordance cosmological model, or to explain the current accelerated phase of the universe. One way to distinguish between General Relativity and modified gravity models is using current astronomical data to measure the growth index $\gamma$, a parameter related to the growth of matter perturbations, which behaves differently in different metric theories. We propose a model independent methodology for determining $\gamma$, where our analyses combine diverse cosmological data sets, namely $\{ f(z_i) \}$, $\{ [f\sigma_8](z_i) \}$, and $\{ H(z_i) \}$, and use Gaussian Processes, a non-parametric approach suitable to reconstruct functions. This methodology is a new consistency test for $\gamma$ constant. Our results show that, for the redshift interval $0 < z < 1$, $\gamma$ is consistent with the constant value $\gamma = 0.55$, expected in General Relativity theory, within $2 \sigma$ confidence level (CL). Moreover, we find $\gamma(z=0)$ = 0.311 $\pm 0.144 $ and $\gamma(z=0) = 0.609 \pm 0.200$ for the reconstructions using the $\{ f(z_i) \}$ and $\{ [f\sigma_8](z_i) \}$ data sets, respectively, values that also agree at a 2$\sigma$ CL with $\gamma = 0.55$. Our methodology and analyses can be considered as an alternative approach in light of the current discussion in the literature that suggests a possible evidence for the growth index evolution., Comment: 11 pages and 8 figures

In this work, we derive for the first time observational constraints on the extended Minimal Theory of Massive Gravity (eMTMG) framework in light of Planck-CMB data, geometrical measurements from Baryon Acoustic Oscillation (BAO), Type Ia supernovae from the recent Pantheon+ samples, and also using the auto and cross-correlations cosmic shear measurements from KIDS-1000 survey. Given the great freedom of dynamics choice for the theory, we consider an observationally motivated subclass in which the background evolution of the Universe goes through a transition from a (positive or negative) value of the effective cosmological constant to another value. From the statistical point of view, we did not find evidence of such a transition, i.e. deviation from the standard $\Lambda$CDM behavior, and from the joint analysis using Planck + BAO + Pantheon+ data, we constrain the graviton mass to $< 6.6 \times 10^{-34}$ eV at 95% CL. We use KIDS-1000 survey data to constrain the evolution of the scalar perturbations of the model and its limits for the growth of structure predicted by the eMTMG scenario. In this case, we find small evidence at 95% CL for a non-zero graviton mass. We interpret and discuss these results in light of the current tension on the $S_8$ parameter. We conclude that, within the subclass considered, the current data are only able to impose upper bounds on the eMTMG dynamics. Given its potentialities beyond the subclass, eMTMG can be classified as a good candidate for modified gravity, serving as a framework in which observational data can effectively constrain (or confirm) the graviton mass and deviations from the standard $\Lambda$CDM behavior., Comment: 16 pages, uses REVTeX, 2 figures

The pursuit of understanding the mysteries surrounding dark energy has sparked significant interest within the field of cosmology. While conventional approaches, such as the cosmological constant, have been extensively explored, alternative theories incorporating scalar field-based models and modified gravity have emerged as intriguing avenues. Among these, teleparallel theories of gravity, specifically the $f(T,\phi)$ formulation, have gained prominence as a means to comprehend dark energy within the framework of teleparallelism. In this study, we investigate two well-studied models of teleparallel dark energy and examine the presence of cosmological singularities within these scenarios. Using the Goriely-Hyde procedure, we examine the dynamical systems governing the cosmological equations of these models. Our analysis reveals that both models exhibit Type IV singularities, but only for a limited range of initial conditions. These results could indicate a potential edge for teleparallel cosmological models over their other modified gravity counterparts, as the models we examine seem to be only allowing for weak singularities that too under non general conditions., Comment: v2, mateches the published version in EPJC, 15 pages with no figures. arXiv admin note: text overlap with arXiv:2310.00452

In this work, we constrain the Hubble constant parameter, $H_0$, using a combination of the Pantheon sample and galaxy clusters (GC) measurements from minimal cosmological assumptions. Assuming the validity of the cosmic distance duality relation, an estimator is created for $H_0$ that only depends on simple geometrical distances, which is evaluated from Pantheon and a GC angular diameter distance sample afterward. The statistical and systematic errors in GC measurements are summed in quadrature in our analysis. We find $H_0 = 67.22 \pm 6.07$ ${\rm km \ s^{-1} Mpc^{-1}}$ in $1\sigma$ confidence level (C.L.). This measurement presents an error of around 9\%, showing that future and better GC measurements can shed light on the current Hubble tension, Comment: 8 pages, two figures

The cosmic acceleration problem remains one of the most significant challenges in cosmology. One of the proposed solutions to this problem is the modification of gravity on large scales. In this paper, we explore the well-known $\mu$-$\Sigma$ parametrization scenarios and confront them with observational data, including the cosmic microwave background (CMB) radiation from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology Telescope (ACT), and South Pole Telescope (SPT), as well as large-scale structure data from the Sloan Digital Sky Survey (SDSS: BAO+RSD) and Pantheon Supernovae (SN) catalog. We employ a Bayesian framework to constrain the model parameters and discuss the implications of our results on the viability of modified gravity theories. Our analysis reveals the strengths and limitations of the $\mu$-$\Sigma$ parametrization and provides valuable insights into the nature of gravity on cosmological scales. From the joint analysis of the ACT + WMAP + SDSS + SN, we find $\mu_0 -1 = 0.02 \pm 0.19$ and $\Sigma_0 -1 = 0.021 \pm 0.068$ at 68% CL. In light of the SPT + WMAP + SDSS + SN, we find $\mu_0 -1 = 0.07 \pm 0.18$ and $\Sigma_0 -1 = -0.009^{+0.078}_{-0.11}$ at 68% CL. In all the analyses carried out, we do not find any deviations from the theory of general relativity. Our results represent an observational update on the well-known $\mu$-$\Sigma$ parameterization in view of current CMB data, independent and competitive with the constraints obtained with the Planck data., Comment: 7 pages, 2 figures, 4 tables. References updated; matches version published in MNRAS

We critically examine the state of current constraints on the dark energy (DE) equation of state (EoS) $w$. Our study is motivated by the observation that, while broadly consistent with the cosmological constant value $w=-1$, several independent probes appear to point towards a slightly phantom EoS ($w \sim -1.03$) which, if confirmed, could have important implications for the Hubble tension. We pay attention to the apparent preference for phantom DE from Planck Cosmic Microwave Background (CMB) data alone, whose origin we study in detail and attribute to a wide range of (physical and geometrical) effects. We deem the combination of Planck CMB, Baryon Acoustic Oscillations, Type Ia Supernovae, and Cosmic Chronometers data to be particularly trustworthy, inferring from this final consensus dataset $w=-1.013^{+0.038}_{-0.043}$, in excellent agreement with the cosmological constant value. Overall, despite a few scattered hints, we find no compelling evidence forcing us away from the cosmological constant (yet)., Comment: 37 pages, 10 figures, 3 tables. v2: additional references added, clarified some points on the analysis methodology, clarified some results. Version accepted for publication in JCAP

Measurements of the $H_0$ and $\sigma_8$ parameters within the standard cosmological model recently highlighted significant statistical tensions between the cosmic microwave background and low-redshift probes, such as local distance ladder, weak lensing and galaxy clustering surveys. In this work, we frame geometrical distances in a model-independent way by means of cosmographic approximations in the range $z \in (0, 2.3)$ to take into account a robust dataset composed of Baryon Acoustic Oscillations (BAO), type Ia Supernovae (SN), Cosmic Chronometer (CC) data, and measurements from Redshift Space Distortions (RSD). From the joint analysis BAO\,+\,SN\,+\,CC\,+\,RSD, we find an accuracy of $\sim$1.4\% and $\sim$3.7\% on $H_0$ and $\sigma_8$, respectively. Our result for $H_0$ is at 2$\sigma$ tension with local measurements by the SH0ES team, while our $\sigma_8$ estimate is at 2.6$\sigma$ tension with Planck-CMB analysis. This inference shows a tension statistically smaller when compared to those estimated via the $\Lambda$CDM model. We also find that the jerk parameter can deviate more than 3$\sigma$ from the $\Lambda$CDM prediction. Under the same cosmographic setup, we also present results by considering a SH0ES Gaussian prior on $H_0$ that allows for improved accuracy of the parameter space of the models. The present work brings observational constraints on $H_0$ and $\sigma_8$ into a new model-independent perspective, which differs from the predictions obtained within the $\Lambda$CDM paradigm., Comment: 12 pages, 6 figures. Matches the version published in PRD

We present a comprehensive analysis of the $\Lambda_{\rm s}$CDM model, which explores the recent conjecture suggesting a rapid transition of the Universe from anti-de Sitter vacua to de Sitter vacua (viz., the cosmological constant switches sign from negative to positive) at redshift ${z_\dagger\sim 2}$, inspired by the graduated dark energy (gDE) model. Our analysis shows that, predicting $z_\dagger\approx1.7$, $\Lambda_{\rm s}$CDM simultaneously addresses the major cosmological tensions of the standard $\Lambda$CDM model, viz., the Hubble constant $H_0$, the Type Ia Supernovae absolute magnitude $M_{\rm B}$, and the growth parameter $S_8$ tensions, along with other less significant tensions such as the BAO Lyman-$\alpha$ discrepancy., Comment: 7 pages, 3 figures, 1 table, and Supplemental material (7 pages, 8 figures, 2 tables)

This paper introduces the class of omnipotent dark energy (DE) models characterized by nonmonotonic energy densities that are capable of attaining negative values with corresponding equation of state parameters featuring phantom divide line (PDL) crossings and singularities. These nontrivial features are phenomenologically motivated by findings of previous studies that reconstruct cosmological functions from observations, and the success of extensions of $\Lambda$CDM, whose actual or effective DE density is omnipotent, in alleviating the observational discordance within $\Lambda$CDM. As an example, we focus on one embodiment of omnipotent DE, viz., the DE parametrization introduced in Di Valentino et al. [Dark energy with phantom crossing and the H0 tension, Entropy 23, 404 (2021)] (DMS20). By updating and extending the datasets used in the original paper where it was introduced, we confirm the effectiveness of DMS20 in alleviating the observational discrepancies. Additionally, we uncover that its negative DE density feature, importance of which was not previously investigated, plays a crucial role in alleviating the tensions, along with the PDL crossing feature that the parametrization presupposes. In particular, we find that there is a positive correlation between the $H_0$ parameter and the scale ($a_p$) at which DE density transitions from negative to positive, in agreement with previous studies that incorporate this transition feature. For our full dataset, the model yields $H_0=70.05 \pm 0.64$ (68% CL) relaxing the $H_0$ tension with a preference of crossing to negative DE densities ($a_p>0$ at 99% CL), along with the constraint $a_m=0.922^{+0.041}_{-0.035}$ on the scale of the presupposed PDL crossing., Comment: 18 pages, 6 figures, 4 tables; matches the version published in Physical Review D

We analyze a cosmological model featuring an interaction between dark energy and dark matter in light of the measurements of the Cosmic Microwave Background released by three independent experiments: the most recent data by the Planck satellite and the Atacama Cosmology Telescope, and WMAP (9-year data). We show that different combinations of the datasets provide similar results, always favoring an interacting dark sector with a $95\%$~CL significance in the majority of the cases. Remarkably, such a preference remains consistent when cross-checked through independent probes, while always yielding a value of the expansion rate $H_0$ consistent with the local distance ladder measurements. We investigate the source of this preference by scrutinizing the angular power spectra of temperature and polarization anisotropies as measured by different experiments., Comment: 15 pages, 2 figures, 1 table, accepted for publication on JCAP

Modification of general relativity (GR) inspired by theories like $f(R)$ gravity is among the most popular ones to explain the late-time acceleration of the Universe as an alternative to the $\Lambda$CDM model. In this work, we use the state-of-the-art BAO+BBN data and the most recent Type Ia supernovae (SNe Ia) sample namely PantheonPlus, including the Cepheid host distances and covariance from SH0ES samples, to robustly constrain the $f(R)$ gravity framework via two of the most popular $f(R)$ models in literature, namely, the Hu-Sawicki and Starobinsky models. Additionally, we consider how the time variation of the Newton's gravitational constant affects the supernovae distance modulus relation. We find a minor evidence for $f(R)$ gravity under the Hu-Sawicki dynamics from BAO+BBN and BAO+BBN+uncalibrated supernovae joint analysis, but the inclusion of Cepheid host distances, makes the model compatible with GR. Further, we notice tendency of this model to relax the $H_0$ tension. In general, in all the analyses carried out in this study with the late time probes, we find both the $f(R)$ models to be consistent with GR at 95\% CL., Comment: 9 pages, 3 figures, 1 table, matches the version published in Physics of Dark Universe

We explore observational constraints on a cosmological model with an interaction between dark energy (DE) and dark matter (DM), using a compilation of 15 measurements of the 2D BAO (i.e., transversal) scale in combination with Planck-CMB data, to explore the parametric space of a class of interacting DE models. We find that 2D BAO measurements can generate different observational constraints compared to the traditional approach of studying the matter clustering in the 3D BAO measurements. Contrary to the observations for the $\Lambda$CDM and IDE models when analyzed with Planck-CMB + 3D BAO data, we note that Planck-CMB + 2D BAO data favor high values of the Hubble constant $H_0$. From the joint analysis with Planck-CMB + 2D BAO + Gaussian prior on $H_0$, we find $H_0 = 73.4 \pm 0.88$ km/s/Mpc. We conclude that the $H_0$ tension is solved in the IDE model with strong statistical evidence (more than 3$\sigma$) for the IDE cosmologies., Comment: 7 Pages, 2 Figures, 2 Tables. Matches the version published in PRD

In this work, we explore how modified gravity theories based on the non-metricity scalar, known as $f(Q)$ gravity, affect the propagation of gravitational waves from inspiraling of binary systems. We discuss forecast constraints on $f(Q)$ gravity by considering standard siren events in two contexts: i) simulated sources of gravitational waves as black hole - neutron star binary systems, emitting in the frequency band of the third-generation detector represented by the Einstein Telescope (ET); ii) three standard siren mock catalogs based on the merger of massive black hole binaries that are expected to be observed in the operating frequency band of the Laser Interferometer Space Antenna (LISA). We find that, within the ET sensitivity, in combination with supernova and cosmic chronometer data, it will be possible to test deviations from general relativity at $<3\%$ accuracy in the redshift range $0

3XMM J185246.6+003317 is a transient magnetar located in the vicinity of the supernova remnant Kes\,79. So far, observations have only set upper limits to its surface magnetic field and spindown, and there is no estimate for its mass and radius. Using ray-tracing modelling and Bayesian inference for the analysis of several light curves spanning a period of around three weeks, we have found that it may be one of the most massive neutron stars to date. In addition, our analysis suggests a multipolar magnetic field structure with a subcritical field strength and a carbon atmosphere composition. Due to the time-resolution limitation of the available light curves, we estimate the surface magnetic field and the mass to be $\log_{10} (B/{\rm G}) = 11.89^{+0.19}_{-0.93}$ and $M=2.09^{+0.16}_{-0.09}$~$M_{\odot}$ at $1\sigma$ confidence level, while the radius is estimated to be $R=12.02^{+1.44}_{-1.42}$ km at $2\sigma$ confidence level. They were verified by simulations, i.e., data injections with known model parameters, and their subsequent recovery. The best-fitting model has three small hot spots, two of them in the southern hemisphere. These are, however, just first estimates and conclusions, based on a simple ray-tracing model with anisotropic emission; we also estimate the impact of modelling on the parameter uncertainties and the relevant phenomena on which to focus in more precise analyses. We interpret the above best-fitting results as due to accretion of supernova layers/interstellar medium onto 3XMM J185246.6+003317 leading to burying and a subsequent re-emergence of the magnetic field, and a carbon atmosphere being formed possibly due to hydrogen/helium diffusive nuclear burning. Finally, we briefly discuss some consequences of our findings for superdense matter constraints., Comment: 14 pages, 5 figures, 4 tables. Accepted for publication in Journal of High Energy Astrophysics (JHEAP)

Cosmic Probes of Fundamental Physics take two primary forms: Very high energy particles (cosmic rays, neutrinos, and gamma rays) and gravitational waves. Already today, these probes give access to fundamental physics not available by any other means, helping elucidate the underlying theory that completes the Standard Model. The last decade has witnessed a revolution of exciting discoveries such as the detection of high-energy neutrinos and gravitational waves. The scope for major developments in the next decades is dramatic, as we detail in this report., Comment: Report of theTopical Group on Cosmic Probes of Fundamental Physics, for the U.S. decadal Particle Physics Planning Exercise (Snowmass 2021)

We investigate two new observational perspectives in the context of torsional gravitational modification of general relativity, i.e., the $f(T)$ gravity: i) We use Pantheon data of type Ia supernovae motivated by a time variation of the Newton's constant on the supernovae distance modulus relation, and find that a joint analysis with Baryon Acoustic Oscillations (BAO) and Big Bang Nucleosynthesis (BBN), i.e., Pantheon+BAO+BBN, provides constraints on the effective free parameter of the theory to be well compatible with the $\Lambda$CDM prediction; ii) We present the framework of $f(T)$ gravity at the level of linear perturbations with the phenomenological functions, namely the effective gravitational coupling $\mu$ and the light deflection parameter $\Sigma$, which are commonly used to parameterize possible modifications of the Poisson equation relating the matter density contrast to the lensing and the Newtonian potentials, respectively. We use the available Cosmic Microwave Background (CMB) data sets from the Planck 2018 release to constrain the free parameters of the $f(T)$ power-law gravity and $\Lambda$CDM models. We find that CMB data, and its joint analyses with Pantheon and BAO data constrain the $f(T)$ power-law gravity scenario to be practically indistinguishable from the $\Lambda$CDM model. We obtain the strongest limits ever reported on $f(T)$ power-law gravity scenario at the cosmological level., Comment: 13 pages, 2 tables, 6 figures; New discussions added; Matches the version published in Physical Review D

Using the latest observational data from Planck-CMB and its combination with the pre-reconstructed full-shape (FS) galaxy power spectrum measurements from the BOSS DR12 sample and eBOSS LRG DR16 sample, we report the observational constraints on the cosmic neutrino properties given by the extended $\Lambda$CDM scenario: $\Lambda$CDM + $N_{\rm eff}$ + $\sum m_{\nu}$ + $c^2_{\rm eff}$ + $c^2_{\rm vis}$ + $\xi_{\nu}$, and its particular case $\Lambda$CDM + $c^2_{\rm eff}$ + $c^2_{\rm vis}$ + $\xi_{\nu}$, where $N_{\rm eff}$, $\sum m_{\nu}$, $c^2_{\rm eff}$, $c^2_{\rm vis}$, $\xi_{\nu}$ are the effective number of species, the total neutrino mass, the sound speed in the neutrinos rest frame, the viscosity parameter and the degeneracy parameter quantifying a cosmological leptonic asymmetry, respectively. We observe that the combination of FS power spectrum measurements with the CMB data significantly improves the parametric space of the models compared to the CMB data alone case. We find no evidence for neutrinos properties other than the ones predicted by the standard cosmological theory. Our most robust observational constraints are given by CMB + BOSS analysis. For the generalized extended $\Lambda$CDM scenario, we find $c^2_{\rm eff}=0.3304^{+0.0064}_{-0.0075}$, $c^2_{\rm vis}=0.301^{+0.037}_{-0.033}$, $\xi_{\nu} < 0.05$, $N_{\rm eff}=2.90 \pm 0.15$ at 68\% CL, with $\sum m_{\nu} < 0.116$ eV at 95\% CL. These are the strongest limits ever reported for these extended $\Lambda$CDM scenarios., Comment: 22 pages, 4 figures, 3 tables; Substantial changes in the text with updated results; matches the version published in JCAP except some additional refs in this version

We explore the role of redshift-space galaxy clustering data in constraining non-gravitational interactions between dark energy (DE) and dark matter (DM), for which state-of-the-art limits have so far been obtained from late-time background measurements. We use the joint likelihood for pre-reconstruction full-shape (FS) galaxy power spectrum and post-reconstruction Baryon Acoustic Oscillation (BAO) measurements from the BOSS DR12 sample, alongside Cosmic Microwave Background (CMB) data from \textit{Planck}: from this dataset combination we infer $H_0=68.02^{+0.49}_{-0.60}\,{\rm km}/{\rm s}/{\rm Mpc}$ and the 2$\sigma$ lower limit $\xi>-0.12$, among the strongest limits ever reported on the DM-DE coupling strength $\xi$ for the particular model considered. Contrary to what has been observed for the $\Lambda$CDM model and simple extensions thereof, we find that the CMB+FS combination returns tighter constraints compared to the CMB+BAO one, suggesting that there is valuable additional information contained in the broadband of the power spectrum. We test this finding by running additional CMB-free analyses and removing sound horizon information, and discuss the important role of the equality scale in setting constraints on DM-DE interactions. Our results reinforce the critical role played by redshift-space galaxy clustering measurements in the epoch of precision cosmology, particularly in relation to tests of non-minimal dark sector extensions of the $\Lambda$CDM model., Comment: 18 Pages, 4 Figures, 2 Tables. Matches the version published in PRD

In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant $H_0$, the $\sigma_8$--$S_8$ tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the $5.0\,\sigma$ tension between the {\it Planck} CMB estimate of the Hubble constant $H_0$ and the SH0ES collaboration measurements. After showing the $H_0$ evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the {\it Planck} CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density $\Omega_m$, and the amplitude or rate of the growth of structure ($\sigma_8,f\sigma_8$). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the $H_0$--$S_8$ tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals.[Abridged], Comment: Contribution to Snowmass 2021. 224 pages, 27 figures. Accepted for publication in JHEAp

Measurements of the cosmological parameter $S_8$ provided by cosmic microwave background and large scale structure data reveal some tension between them, suggesting that the clustering features of matter in these early and late cosmological tracers could be different. In this work, we use a supervised learning method designed to solve Bayesian approach to regression, known as Gaussian Processes regression, to quantify the cosmic evolution of $S_8$ up to $z \sim 1.5$. For this, we propose a novel approach to find firstly the evolution of the function $\sigma_8(z)$, then we find the function $S_8(z)$. As a sub-product we obtain a minimal cosmological model-dependent $\sigma_8(z=0)$ and $S_8(z=0)$ estimates. We select independent data measurements of the growth rate $f(z)$ and of $[f\sigma_8](z)$ according to criteria of non-correlated data, then we perform the Gaussian reconstruction of these data sets to obtain the cosmic evolution of $\sigma_8(z)$, $S_8(z)$, and the growth index $\gamma(z)$. Our statistical analyses show that $S_8(z)$ is compatible with Planck $\Lambda$CDM cosmology; when evaluated at the present time we find $\sigma_8(z=0) = 0.766 \pm 0.116$ and $S_8(z=0) = 0.732 \pm 0.115$. Applying our methodology to the growth index, we find $\gamma(z=0) = 0.465 \pm 0.140$. Moreover, we compare our results with others recently obtained in the literature. In none of these functions, i.e. $\sigma_8(z)$, $S_8(z)$, and $\gamma(z)$, do we find significant deviations from the standard cosmology predictions., Comment: 8 pages and 10 figures. Accepted for publication in EPJC

Motivated by future gravitational waves observations, we perform forecasts analysis to constrain a possible time variation of the fine structure constant ($\alpha$) within the context of the so-called runaway dilaton model. For this purpose, some gravitational-wave standard sirens mock data within the perspective of Einstein Telescope and LISA mission were considered jointly with current strong gravitational lensing systems observations. We find that future standard sirens observations can also play an important role in the search for possible variations of $\alpha$ within the methodology presented in this work., Comment: Accepted version by the Astroparticle Physics

We propose a novel approach to obtain the growth rate of cosmic structures, $f(z)$, from the evolution of the cosmic homogeneity scale, $R_{\text{H}}(z)$. Our methodology needs two ingredients in a specific functional form: $R_{\text{H}}(z)$ data and the matter two-point correlation function today, i.e., $\xi(r, z=0)$. We use a Gaussian Process approach to reconstruct the function $R_{\text{H}}$. In the absence of suitable observational information of the matter correlation function in the local Universe, $z \simeq 0$, we assume a fiducial cosmology to obtain $\xi(r, z=0)$. For this reason, our final result turns out to be a consistency test of the cosmological model assumed. Our results show a good agreement between: (i) the growth rate $f^{R_{\text{H}}}(z)$ obtained through our approach, (ii) the $f^{\Lambda\text{CDM}}(z)$ expected in the fiducial model, and (iii) the best-fit $f(z)$ from data compiled in the literature. Moreover, using this data compilation, we perform a Gaussian Process to reconstruct the growth rate function $f^{\text{data}}(z)$ and compare it with the function $f^{R_{\text{H}}}(z)$ finding a concordance of $< \!2 \,\sigma$, a good result considering the few data available for both reconstruction processes. With more accurate $R_{\text{H}}(z)$ data, from forthcoming surveys, the homogeneity scale function might be better determined and would have the potential to discriminate between $\Lambda$CDM and alternative scenarios as a new cosmological observable., Comment: Accepted for publication in MNRAS

In this manuscript we reassess the potential of interacting dark matter-dark energy models in solving the Hubble constant tension. These models have been proposed but also questioned as possible solutions to the $H_0$ problem. Here we examine several interacting scenarios against cosmological observations, focusing on the important role played by the calibration of Supernovae data. In order to reassess the ability of interacting dark matter-dark energy scenarios in easing the Hubble constant tension, we systematically confront their theoretical predictions using a prior on the Supernovae Ia absolute magnitude $M_B$, which has been argued to be more robust and certainly less controversial than using a prior on the Hubble constant $H_0$. While some data combinations do not show any preference for interacting dark sectors and in some of these scenarios the clustering $\sigma_8$ tension worsens, interacting cosmologies with a dark energy equation of state $w<-1$ are preferred over the canonical $\Lambda$CDM picture even with CMB data alone and also provide values of $\sigma_8$ in perfect agreement with those from weak lensing surveys. Future cosmological surveys will test these exotic dark energy cosmologies by accurately measuring the dark energy equation of state and its putative redshift evolution., Comment: 12 pages, 5 figures, 5 tables. Version accepted for publication in PRD

Standard sirens (SS) are the gravitational wave analog of the astronomical standard candles, and can provide powerful information about the dynamics of the Universe up to very high $z$ values. In this work, we generate three mock SS catalogs based on the merger of massive black hole binaries which are expected to be observed in the LISA operating frequency band. Then, we perform an analysis to test modifications of general relativity (GR) inspired by the No Slip gravity framework. We find that in the best scenarios, we can constrain the free parameters which quantify deviations from GR to 21\% accuracy, while the Hubble parameter can be simultaneously fit to 6\% accuracy. In combination with CMB information, we find a 15\% accuracy on the modified gravity free parameters and 0.7\% accuracy on the Hubble parameter. The SS events at very large cosmological distances to be observed in LISA band will provide a unique way to test nature of gravity, but in the context of the analysis performed here, it will not be possible to distinguish the No Slip gravity from GR., Comment: 8 pages, 6 figures, 3 tables, improved version. Accepted for publication in MNRAS

A possible detection of sub-solar mass ultra-compact objects would lead to new perspectives on the existence of black holes that are not of astrophysical origin and/or pertain to formation scenarios of exotic ultra-compact objects. Both possibilities open new perspectives for better understanding of our universe. In this work, we investigate the significance of detection of sub-solar mass binaries with components mass in the range: $10^{-2} M_\odot$ up to 1$M_\odot$, within the expected sensitivity of the ground-based gravitational waves detectors of third-generation, viz., the Einstein Telescope (ET) and the Cosmic Explorer (CE). Assuming a minimum of amplitude signal-to-noise ratio for detection, viz., $\rho = 8$, we find that the maximum horizon distances for an ultra-compact binary system with components mass $10^{-2} \, M_\odot$ and 1$M_\odot$ are 40 Mpc and 1.89 Gpc, respectively, for ET, and 125 Mpc and 5.8 Gpc, respectively, for CE. Other cases are also presented in the text. We derive the merger rate, and discuss consequences on the abundances of primordial black hole (PBH), $f_{\rm PBH}$. Considering the entire mass range [$10^{-2}$ - 1]$M_\odot$, we find $f_{\rm PBH} < 0.70$ ($<$ $0.06$) for ET (CE), respectively., Comment: 7 Pages, 4 Figures, 1 Table

It has been intensively discussed if modifications in the dynamics of the Universe at late times is able or not to solve the $H_0$ tension. On the other hand, it has also been argued that the $H_0$ tension is actually a tension on the supernova absolute magnitude $M_B$. In this work, we robustly constraint $M_B$ using Pantheon Supernovae Ia (SN) sample, Baryon Acoustic Oscillations (BAO), and Big Bang Nucleosynthesis (BBN) data, and assess the $M_B$ tension by comparing three theoretical models, namely the standard $\Lambda$CDM, the $w$CDM and a non-gravitational interaction (IDE) between dark energy (DE) and dark matter (DM). We find that the IDE model can solve the $M_B$ tension with a coupling different from zero at 95\% CL, confirming the results obtained using a $H_0$ prior., Comment: 8 pages, 2 Figures, 2 Tables. Matches the version published in PRD

We investigate the Minimal Theory of Massive Gravity (MTMG) in the light of different observational data sets which are in tension within the $\Lambda$CDM cosmology. In particular, we analyze MTMG model, for the first time, with the Planck-CMB data, and how these precise measurements affect the free parameters of the theory. The MTMG model can affect the CMB power spectrum at large angular scales and cause a suppression on the amplitude of the matter power spectrum. We find that on adding Planck-CMB data, the graviton has a small, positive, but non-zero mass at 68\% confidence level, and from this perspective, we show that the tension between redshift space distortions measurements and Planck-CMB data in the parametric space $S_8 - \Omega_m$ can be resolved within the MTMG scenario. Through a robust and accurate analysis, we find that the $H_0$ tension between the CMB and the local distance ladder measurements still remains but can be reduced to $\sim3.5\sigma$ within the MTMG theory. The MTMG is very well consistent with the CMB observations, and undoubtedly, it can serve as a viable candidate amongst other modified gravity theories., Comment: 14 pages, 7 figures, 2 tables. Matches the version published in PRD

Within the $\Lambda$CDM model, measurements from recent Cosmic Microwave Background (CMB) and weak lensing (WL) surveys have uncovered a $\sim 3\sigma$ disagreement in the inferred value of the parameter $S_8 \equiv \sigma_8\sqrt{\Omega_m/0.3}$, quantifying the amplitude of late-time matter fluctuations. Before questioning whether the $S_8$ discrepancy calls for new physics, it is important to assess the view of measurements other than CMB and WL ones on the discrepancy. Here, we examine the role of measurements of the growth rate $f(z)$ in arbitrating the $S_8$ discrepancy, considering measurements of $f\sigma_8(z)$ from Redshift-Space Distortions (RSD). Our baseline analysis combines RSD measurements with geometrical measurements from Baryon Acoustic Oscillations (BAO) and Type Ia Supernovae (SNeIa), given the key role of the latter in constraining $\Omega_m$. From this combination and within the $\Lambda$CDM model we find $S_8 = 0.762^{+0.030}_{-0.025}$, and quantify the agreement between RSD+BAO+SNeIa and \textit{Planck} to be at the $2.2\sigma$ level: the mild disagreement is therefore compatible with a statistical fluctuation. We discuss combinations of RSD measurements with other datasets, including the $E_G$ statistic. This combination increases the discrepancy with \textit{Planck}, but we deem it significantly less robust. Our earlier results are stable against an extension where we allow the dark energy equation of state $w$ to vary. We conclude that, from the point of view of combined growth rate and geometrical measurements, there are hints, but no strong evidence yet, for the \textit{Planck} $\Lambda$CDM cosmology over-predicting the amplitude of matter fluctuations at redshifts $z \lesssim 1$. From this perspective, it might therefore still be premature to claim the need for new physics from the $S_8$ discrepancy., Comment: 13 pages, 1 table, 3 figures. Accepted for publication in MNRAS

As is well known, pulsars are extremely stable rotators. However, although slowly, they spin down thanks to brake mechanisms, which are in fact still subject of intense investigation in the literature. Since pulsars are usually modelled as highly magnetized neutron stars that emit beams of electromagnetic radiation out of their magnetic poles, it is reasonable to consider that the spindown has to do with a magnetic brake. Although an interesting and simple idea, a pure magnetic brake is not able to adequately account for the spindown rate. Thus, many alternative spindown mechanisms appear in the literature, among them the pulsar wind model, where a wind of particles coming from the pulsar itself can carry part of its rotational kinetic energy. Such a spindown mechanism depends critically on three parameters, namely, the dipole magnetic field $B$, the angle between the magnetic and rotation axes $(\phi)$, and the density of primary particles $(\zeta)$ of the pulsar's magnetosphere. Differently from a series of articles in this subject, we consider for the first time in the literature a statistical modelling which includes a combination of a dipole magnetic and wind brakes. As a result, we are able to constrain the above referred parameters in particular for Crab and Vela pulsars., Comment: 6 Pages, 6 Figures, 1 Table. Accepted for publication in the Astrophysical Journal (ApJ)

Interacting dark matter (DM) - dark energy (DE) models have been intensively investigated in the literature for their ability to fit various data sets as well as to explain some observational tensions persisting within the $\Lambda$CDM cosmology. In this work, we employ the Gaussian processes (GP) algorithm to perform a joint analysis by using the geometrical cosmological probes such as Cosmic chronometers, Supernova Type Ia, Baryon Acoustic Oscillations, and the H0LiCOW lenses sample to infer a reconstruction of the coupling function between the dark components in a general framework, where the DE can assume a dynamical character via its equation of state. In addition to the joint analysis with these data, we simulate a catalogue with standard siren events from binary neutron star mergers, within the sensitivity predicted by the Einstein Telescope, to reconstruct the dark sector coupling with more accuracy in a robust way. We find that the particular case, where $w = -1$ is fixed on the DE nature, has a statistical preference for an interaction in the dark sector at late times. In the general case, where $w(z)$ is analysed, we find no evidence for such dark coupling, and the predictions are compatible with the $\Lambda$CDM paradigm. When the mock events of the standard sirens are considered to improve the kernel in GP predictions, we find a preference for an interaction in the dark sector at late times., Comment: 8 page, 4 figures, Comments are welcome. This is the final version published in MNRAS, with the correction of some types and without changing the results

Gaussian processes (GP) provide an elegant and model-independent method for extracting cosmological information from the observational data. In this work, we employ GP to perform a joint analysis by using the geometrical cosmological probes such as Supernova Type Ia (SN), Cosmic chronometers (CC), Baryon Acoustic Oscillations (BAO), and the H0LiCOW lenses sample to constrain the Hubble constant $H_0$, and reconstruct some properties of dark energy (DE), viz., the equation of state parameter $w$, the sound speed of DE perturbations $c^2_s$, and the ratio of DE density evolution $X = \rho_{\rm de}/\rho_{\rm de,0}$. From the joint analysis SN+CC+BAO+H0LiCOW, we find that $H_0$ is constrained at 1.1\% precision with $H_0 = 73.78 \pm 0.84$ km s$^{-1}$Mpc$^{-1}$, which is in agreement with SH0ES and H0LiCOW estimates, but in $\sim$6.2$\sigma$ tension with the current CMB measurements of $H_0$. With regard to the DE parameters, we find $c^2_s < 0$ at $\sim$2$\sigma$ at high $z$, and the possibility of $X$ to become negative for $z > 1.5$. We compare our results with the ones obtained in the literature, and discuss the consequences of our main results on the DE theoretical framework., Comment: 13 pages, 9 captioned figures. Matches the version published in EPJC

The current cosmological probes have provided a fantastic confirmation of the standard $\Lambda$ Cold Dark Matter cosmological model, that has been constrained with unprecedented accuracy. However, with the increase of the experimental sensitivity a few statistically significant tensions between different independent cosmological datasets emerged. While these tensions can be in portion the result of systematic errors, the persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the need for new physics. In this Letter of Interest we will focus on the $4.4\sigma$ tension between the Planck estimate of the Hubble constant $H_0$ and the SH0ES collaboration measurements. After showing the $H_0$ evaluations made from different teams using different methods and geometric calibrations, we will list a few interesting new physics models that could solve this tension and discuss how the next decade experiments will be crucial., Comment: Snowmass2021 - Letter of Interest

A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios. The recent observations, while broadly consistent with a spatially flat standard $\Lambda$ Cold Dark Matter ($\Lambda$CDM) model, are showing tensions that still allow (and, in some cases, even suggest) a few percent deviations from a flat universe. In particular, the Planck Cosmic Microwave Background power spectra, assuming the nominal likelihood, prefer a closed universe at more than 99\% confidence level. While new physics could be in action, this anomaly may be the result of an unresolved systematic error or just a statistical fluctuation. However, since a positive curvature allows a larger age of the Universe, an accurate determination of the age of the oldest objects provides a smoking gun in confirming or falsifying the current flat $\Lambda$CDM model., Comment: Snowmass2021 - Letter of Interest