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Abstract In this study, we investigate deviations from the Planck- $$\Lambda $$ Λ CDM model in the late universe ( $$z \lesssim 2.5$$ z ≲ 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 $$\delta (z)$$ δ ( z ) , which measures deviations of the Hubble parameter from the Planck- $$\Lambda $$ Λ CDM predictions, we identify intriguing features at low ( $$z \lesssim 0.5$$ z ≲ 0.5 ) and high ( $$z \gtrsim 2$$ z ≳ 2 ) redshifts. Deviations from the Planck- $$\Lambda $$ Λ CDM model were not significant between $$0.5\lesssim z \lesssim 2$$ 0.5 ≲ z ≲ 2 . 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 $$z\gtrsim 2$$ z ≳ 2 , transitioning with a singularity around $$z\sim 2$$ z ∼ 2 to usual phantom traits in $$1\lesssim z\lesssim 2$$ 1 ≲ z ≲ 2 . DE characteristics differ between scenarios ( $$H_0$$ H 0 -SH0ES and $$H_0$$ H 0 - $$\Lambda $$ Λ &CMB), with $$H_0$$ H 0 -SH0ES leaning towards phantom traits and $$H_0$$ H 0 - $$\Lambda $$ Λ &CMB towards quintessence. We suggest exploring new physics at $$z\lesssim 0.5$$ z ≲ 0.5 and $$1.5\lesssim z\lesssim 2.5$$ 1.5 ≲ z ≲ 2.5 , particularly around $$z = 2$$ z = 2 , to understand cosmological tensions such as $$H_0$$ H 0 and $$S_8$$ S 8 .

Abstract 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 $$\gamma $$ γ , a parameter related to the growth of matter perturbations, which behaves differently in different metric theories. We propose a model independent methodology for determining $$\gamma $$ γ , where our analyses combine diverse cosmological data sets, namely $$\{ f(z_i) \}$$ { f ( z i ) } , $$\{ [f\sigma _8](z_i) \}$$ { [ f σ 8 ] ( z i ) } , and $$\{ H(z_i) \}$$ { H ( z i ) } , and use Gaussian Processes, a non-parametric approach suitable to reconstruct functions. This methodology is a new consistency test for $$\gamma $$ γ constant. Our results show that, for the redshift interval $$0< z < 1$$ 0 < z < 1 , $$\gamma $$ γ is consistent with the constant value $$\gamma = 0.55$$ γ = 0.55 , expected in General Relativity theory, within $$2 \sigma $$ 2 σ confidence level (CL). Moreover, we find $$\gamma (z=0)$$ γ ( z = 0 ) = 0.311 $$\pm 0.144 $$ ± 0.144 and $$\gamma (z=0) = 0.609 \pm 0.200$$ γ ( z = 0 ) = 0.609 ± 0.200 for the reconstructions using the $$\{ f(z_i) \}$$ { f ( z i ) } and $$\{ [f\sigma _8](z_i) \}$$ { [ f σ 8 ] ( z i ) } data sets, respectively, values that also agree at a 2 $$\sigma $$ σ CL with $$\gamma = 0.55$$ γ = 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.

Abstract The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational-wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational-wave observations by LISA to probe the universe.

Abstract The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA’s first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed; ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or interme-diate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe.

Abstract Measurements of the cosmological parameter $$S_8$$ 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 $$S_8$$ S 8 up to $$z \sim 1.5$$ z ∼ 1.5 . For this, we propose a novel approach to find firstly the evolution of the function $$\sigma _8(z)$$ σ 8 ( z ) , then we find the function $$S_8(z)$$ S 8 ( z ) . As a sub-product we obtain a minimal cosmological model-dependent $$\sigma _8(z=0)$$ σ 8 ( z = 0 ) and $$S_8(z=0)$$ S 8 ( z = 0 ) estimates. We select independent data measurements of the growth rate f(z) and of $$[f\sigma _8](z)$$ [ f σ 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 $$\sigma _8(z)$$ σ 8 ( z ) , $$S_8(z)$$ S 8 ( z ) , and the growth index $$\gamma (z)$$ γ ( z ) . Our statistical analyses show that $$S_8(z)$$ S 8 ( z ) is compatible with Planck $$\Lambda $$ Λ CDM cosmology; when evaluated at the present time we find $$\sigma _8(z=0) = 0.766 \pm 0.116$$ σ 8 ( z = 0 ) = 0.766 ± 0.116 and $$S_8(z=0) = 0.732 \pm 0.115$$ S 8 ( z = 0 ) = 0.732 ± 0.115 . Applying our methodology to the growth index, we find $$\gamma (z=0) = 0.465 \pm 0.140$$ γ ( z = 0 ) = 0.465 ± 0.140 . Moreover, we compare our results with others recently obtained in the literature. In none of these functions, i.e. $$\sigma _8(z)$$ σ 8 ( z ) , $$S_8(z)$$ S 8 ( z ) , and $$\gamma (z)$$ γ ( z ) , do we find significant deviations from the standard cosmology predictions.

The NANOGrav 15 yr data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations.

Abstract 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 $$H_0$$ H 0 , and reconstruct some properties of dark energy (DE), viz., the equation of state parameter w, the sound speed of DE perturbations $$c^2_s$$ c s 2 , and the ratio of DE density evolution $$X = \rho _\mathrm{de}/\rho _\mathrm{de,0}$$ X = ρ de / ρ de , 0 . From the joint analysis SN+CC+BAO+H0LiCOW, we find that $$H_0$$ H 0 is constrained at 1.1% precision with $$H_0 = 73.78 \pm 0.84\ \hbox {km}\ \hbox {s}^{-1}\,\hbox {Mpc}^{-1}$$ H 0 = 73.78 ± 0.84 km s - 1 Mpc - 1 , which is in agreement with SH0ES and H0LiCOW estimates, but in $$\sim 6.2 \sigma $$ ∼ 6.2 σ tension with the current CMB measurements of $$H_0$$ H 0 . With regard to the DE parameters, we find $$c^2_s < 0$$ c s 2 < 0 at $$\sim 2 \sigma $$ ∼ 2 σ at high z, and the possibility of X to become negative for $$z > 1.5$$ 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.

Abstract We use observations related to the variation of fundamental constants, in order to impose constraints on the viable and most used f(T) gravity models. In particular, for the fine-structure constant we use direct measurements obtained by different spectrographic methods, while for the effective Newton constant we use a model-dependent reconstruction, using direct observational Hubble parameter data, in order to investigate its temporal evolution. We consider two f(T) models and we quantify their deviation from $$\Lambda $$ Λ CDM cosmology through a sole parameter. Our analysis reveals that this parameter can be slightly different from its $$\Lambda $$ Λ CDM value, however, the best-fit value is very close to the $$\Lambda $$ Λ CDM one. Hence, f(T) gravity is consistent with observations, nevertheless, as every modified gravity, it may exhibit only small deviations from $$\Lambda $$ Λ CDM cosmology, a feature that must be taken into account in any f(T) model-building.

La conservación debe darse con base en la realidad social, económica y ecológica de nuestros países. Tomando en cuenta lo anterior y como punto inicial en una exposición sobre los efectos que se pueden producir en la zona marítimo-terrestre por una mala planificación o un abuso en los desarrollos comunales y turísticos de dichas zonas, se puede afirmar que ninguna medida para el desarrollo de la industria turística debe atentar contra la misma razón de ser de la industria, o sea, los recursos naturales y las bellezas escénicas.

The Sunyaev–Zel’dovich (SZ) effect is a global distortion of the Cosmic Microwave Background (CMB) spectrum as a result of its interaction with a hot electron plasma in the intracluster medium of large structures gravitationally viralized such as galaxy clusters (GC). Furthermore, this hot gas of electrons emits X-rays due to its fall in the gravitational potential well of the GC. The analysis of SZ and X-ray data provides a method for calculating distances to GC at high redshifts. On the other hand, many galaxies and GC produce a Strong Gravitational Lens (SGL) effect, which has become a useful astrophysical tool for cosmology. We use these cosmological tests in addition to more traditional ones to constrain some alternative dark energy (DE) models, including the study of the history of cosmological expansion through the cosmographic parameters. Using Akaike and Bayesian Information Criterion, we find that the w C D M and Λ C D M models are the most favoured by the observational data. In addition, we found at low redshift a peculiar behavior of slowdown of the universe, which occurs in dynamical DE models when we use data from GC.

In order to explain the current acceleration of the universe, the fine-tuning problem of the cosmological constant Λ and the cosmic coincidence problem, different alternative models have been proposed in the literature. We use the most recent observational data from CMB (Planck 2018 final data release) and LSS (SDSS, WiggleZ, VIPERS) to constrain dynamical dark energy (DE) models. The CMB shift parameter, which traditionally has been used to determine the main cosmological parameters of the standard model Λ CDM , is employed in addition to data from redshift-space distortions through the growth parameter A (z) = f (z) σ 8 (z) to constrain the mass variance σ 8 . BAO data are also used to study the history of the cosmological expansion and the main properties of DE. From the evolution of q (z) , we found a slowdown of acceleration behavior at low redshifts, and by using the Akaike and Bayesian Information Criteria (AIC, BIC), we discriminate different models to find those that are better suited to the observational data, finding that the interacting dark energy (IDE) model is the most favored by observational data, including information from SNIa and Hz. The analysis shows that the IDE model is followed closely by EDE and Λ CDM models, which in some cases fit better the observational data with individual probes. [ABSTRACT FROM AUTHOR]

We have shown that the connection between the number of bits and the area of the holographic screen, where both were established in Verlinde's theory of entropic gravity, may depend on the previously chosen thermostatistics theory. Starting from the Boltzmann-Gibbs (BG) theory, we have reobtained the usual dependence of the number of bits and the holographic screen area. After that, using the Kaniadakis microcanonical entropy formula within the entropic gravity formalism, we have derived another relation between the bits number and the holographic screen area. We have used this new relation to derive three Newtonian-type accelerations in the context of Kaniadakis' statistics which are a modified gravitational acceleration, a modified MOND theory and a modified Friedmann equation. We have obtained a kappa version of the Tully-Fisher (TF) relation which displays a dependence of the distance from the star in contrast to the standard TF expression. [ABSTRACT FROM AUTHOR]

In this paper we have shown that the connection between the number of bits and the area of the holographic screen, where both were established in Verlinde's theory of entropic gravity, may depend on the thermostatistics theory previously chosen. Starting from the Boltzmann-Gibbs (BG) theory, we have reobtained the usual dependence of both, bits number and area. After that, using Tsallis' entropy concept within the entropic gravity formalism, we have derived another relation between the bits number and the holographic screen area. We have used this new relation to derive three Newtonian-type accelerations in the context of Tsallis' statistics which are a modified gravitational acceleration, a modified MOND theory and a modified Friedmann equation. Moreover we have obtained a nonextensive version of the Tully-Fisher (TF) relation which shows a dependence of the distance of the star in contrast to the standard TF expression. The BG limit gives the standard TF law. [ABSTRACT FROM AUTHOR]

In this work, we have illustrated the difference between both Tsallis and Kaniadakis entropies through cosmological models obtained from the formalism proposed by Padmanabhan, which is called holographic equipartition law. Similarly to the formalism proposed by Komatsu, we have obtained an extra driving constant term in the Friedmann equation if we deform the Tsallis entropy by Kaniadakis' formalism. We have considered initially Tsallis entropy as the black-hole (BH) area entropy. This constant term may lead the universe to be in an accelerated or decelerated mode. On the other hand, if we start with the Kaniadakis entropy as the BH area entropy and then by modifying the Kappa expression by Tsallis' formalism, the same absolute value but with opposite sign is obtained. In an opposite limit, no driving inflation term of the early universe was derived from both deformations. [ABSTRACT FROM AUTHOR]

The study of avian diversity in agroecosystems is a topic of great interest for understanding the dynamics of bird communities in urban environments. The objective of this study was to identify the level of overlap in the selection of nesting sites of some bird species in orange orchards located in the town of Algemesí, province of Valencia, Spain, and their vertical distribution in relation to nesting microsites. An intensive search for tree nests was carried out, and microsite variables such as tree height, canopy coverage, nest location height, and distance from the nest to the edge were measured. Statistical analyses included PERMANOVA and discriminant analysis to identify significant differences and groupings among species based on nesting variables. In total, 98 nests belonging to six species of passerine birds (Sylvia melanocephala, Turdus merula, Serinus serinus, Chloris chloris, Turdus philomelos, and Muscicapa striata) were found. Different phenological patterns were observed among the species, and nesting site characteristics varied depending on nest location height and distance to the edge. The choice of nesting site for Turdus philomelos varied compared to the other species. These results suggest that the different life histories of the species influence the segregation of nesting sites, which in turn affects the coexistence and structure of the bird community.