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We are merging a large participatory science effort with machine learning to enhance the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX). Our overall goal is to remove false positives, allowing us to use lower signal-to-noise data and sources with low goodness-of-fit. With six million classifications through Dark Energy Explorers, we can confidently determine if a source is not real at over 94% confidence level when classified by at least 10 individuals; this confidence level increases for higher signal-to-noise sources. To date, we have only been able to apply this direct analysis to 190,000 sources. The full sample of HETDEX will contain around 2–3 million sources, including nearby galaxies ([O ii ] emitters), distant galaxies (Ly α emitters or LAEs), false positives, and contamination from instrument issues. We can accommodate this tenfold increase by using machine learning with visually vetted samples from Dark Energy Explorers. We have already increased by over tenfold the number of sources that have been visually vetted from our previous pilot study where we only had 14,000 visually vetted LAE candidates. This paper expands on the previous work by increasing the visually vetted sample from 14,000 to 190,000. In addition, using our currently visually vetted sample, we generate a real or false positive classification for the full candidate sample of 1.2 million LAEs. We currently have approximately 17,000 volunteers from 159 countries around the world. Thus, we are applying participatory or citizen scientist analysis to our full HETDEX data set, creating a free educational opportunity that requires no prior technical knowledge. [ABSTRACT FROM AUTHOR]

We point out that dark matter and dark energy arise naturally in a recently proposed model of combinatorial quantum gravity. Dark energy is due to the ground-state curvature at finite coupling, dark matter arises from allotropy in the discrete structure of space-time. The stable structure of the space-time 'crystal' represents the curved background, the coexisting metastable allotropes of higher curvature and energy are natural candidates for dark matter. We thus suggest that dark energy and dark matter are two manifestation of quantum gravity. [ABSTRACT FROM AUTHOR]

Cosmological information is usually extracted from the Lyman- |$\alpha$| (Ly  |$\alpha$|⁠) forest correlations using only either large-scale information interpreted through linear theory or using small-scale information interpreted by means of expensive hydrodynamical simulations. A complete cosmological interpretation of the three-dimensional (3D) correlations at all measurable scales is challenged by the need of more realistic models including the complex growth of non-linear small scales that can only be studied within large hydrodynamical simulations. Past works were often limited by the trade-off between the simulated cosmological volume and the resolution of the low-density intergalactic medium from which the Ly  |$\alpha$| signal originates. We conduct a suite of hydrodynamical simulations of the intergalactic medium, including one of the largest Ly  |$\alpha$| simulations ever performed in terms of volume (640 |$\, h^{-1}\, \mathrm{Mpc}$|⁠), alongside simulations in smaller volumes with resolutions up to 25 |$\, h^{-1}\, \mathrm{kpc}$|⁠ , which will be further improved to show resolution convergence in future studies. We compare the 3D Ly  |$\alpha$| power spectra (⁠|$P_{3\mathrm{D},\alpha }$|⁠) predicted by those simulations to different non-linear models. The inferred Ly  |$\alpha$| bias and redshift space distortion parameters, |$b_\alpha$| and |$\beta _\alpha$| are in remarkable agreement with those measured in SDSS (Sloan Digital Sky Survey) and DESI (Dark Energy Spectroscopic Instrument) data. We find that, contrary to intuition, the convergence of large-scale modes of the |$P_{3\mathrm{D},\alpha }$|⁠ , which determines |$\beta _\alpha$|⁠ , is primarily influenced by the resolution of the simulation box through mode coupling, rather than the box size itself. Finally, we study the Baryon Acoustic Oscillation (BAO) signal encoded in |$P_{3\mathrm{D},\alpha }$|⁠. For the first time with a hydrodynamical simulation, we clearly detect the BAO signal; however, we only marginally detect its damping, associated with the non-linear growth of the structures. [ABSTRACT FROM AUTHOR]

Studies have shown that the morphologies of galaxies are substantially transformed following coalescence after a merger, but post-mergers are notoriously difficult to identify, especially in imaging that is shallow or low resolution. We train convolutional neural networks (CNNs) to identify simulated post-merger galaxies in a range of image qualities, modelled after five real surveys: the Sloan Digital Sky Survey (SDSS), the Dark Energy Camera Legacy Survey (DECaLS), the Canada–France Imaging Survey (CFIS), the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), and the Legacy Survey of Space and Time (LSST). Holding constant all variables other than imaging quality, we present the performance of the CNNs on reserved test set data for each image quality. The success of CNNs on a given data set is found to be sensitive to both imaging depth and resolution. We find that post-merger recovery generally increases with depth, but that limiting 5 |$\sigma$| point-source depths in excess of |$\sim 25$| mag, similar to what is achieved in CFIS, are only marginally beneficial. Finally, we present the results of a cross-survey inference experiment, and find that CNNs trained on a given image quality can sometimes be applied to different imaging data to good effect. The work presented here therefore represents a useful reference for the application of CNNs for merger searches in both current and future imaging surveys. [ABSTRACT FROM AUTHOR]

We present an in-depth investigation of galaxy clustering based on a new suite of realistic large-box galaxy formation simulations in |$f(R)$| gravity, with a subgrid physics model that has been recalibrated to reproduce various observed stellar and gas properties. We focus on the two-point correlation functions of the luminous red galaxies (LRGs) and emission line galaxies (ELGs), which are primary targets of ongoing and future galaxy surveys such as Dark Energy Spectroscopic Instrument (DESI). One surprising result is that, due to several non-trivial effects of modified gravity on matter clustering and the galaxy–halo connection, the clustering signal does not depend monotonically on the fifth-force strength. For LRGs, this complicated behaviour poses a challenge to meaningfully constraining this model. For ELGs, in contrast, this can be straightforwardly explained by the time evolution of the fifth force, which means that weaker |$f(R)$| models can display nearly the same – up to 25 per cent – deviations from Lambda cold dark matter model as the strongest ones, albeit at lower redshifts. This implies that even very weak |$f(R)$| models can be strongly constrained, unlike with most other observations. Our results show that galaxy formation acquires a significant environment dependence in |$f(R)$| gravity, which, if not properly accounted for, may lead to biased constraints on the model. This highlights the essential role of hydrodynamical simulations in future tests of gravity exploring precision galaxy-clustering data from the likes of DESI and Euclid. [ABSTRACT FROM AUTHOR]

Low-density cosmic voids gravitationally lens the cosmic microwave background (CMB), leaving a negative imprint on the CMB convergence |$\kappa$|⁠. This effect provides insight into the distribution of matter within voids, and can also be used to study the growth of structure. We measure this lensing imprint by cross-correlating the Planck CMB lensing convergence map with voids identified in the Dark Energy Survey Year 3 (DES Y3) data set, covering approximately 4200 deg |$^2$| of the sky. We use two distinct void-finding algorithms: a 2D void-finder that operates on the projected galaxy density field in thin redshift shells, and a new code, Voxel , which operates on the full 3D map of galaxy positions. We employ an optimal matched filtering method for cross-correlation, using the Marenostrum Institut de Ciències de l'Espai N -body simulation both to establish the template for the matched filter and to calibrate detection significances. Using the DES Y3 photometric luminous red galaxy sample, we measure |$A_\kappa$|⁠ , the amplitude of the observed lensing signal relative to the simulation template, obtaining |$A_\kappa = 1.03 \pm 0.22$| (⁠|$4.6\sigma$| significance) for Voxel and |$A_\kappa = 1.02 \pm 0.17$| (⁠|$5.9\sigma$| significance) for 2D voids, both consistent with Lambda cold dark matter expectations. We additionally invert the 2D void-finding process to identify superclusters in the projected density field, for which we measure |$A_\kappa = 0.87 \pm 0.15$| (⁠|$5.9\sigma$| significance). The leading source of noise in our measurements is Planck noise, implying that data from the Atacama Cosmology Telescope, South Pole Telescope and CMB-S4 will increase sensitivity and allow for more precise measurements. [ABSTRACT FROM AUTHOR]

Type Ia Supernovae (SNe Ia) are a critical tool in measuring the accelerating expansion of the universe. Recent efforts to improve these standard candles have focused on incorporating the effects of dust on distance measurements with SNe Ia. In this paper, we use the state-of-the-art Dark Energy Survey 5 year sample to evaluate two different families of dust models: empirical extinction models derived from SNe Ia data and physical attenuation models from the spectra of galaxies. In this work, we use realistic simulations of SNe Ia to forward-model different models of dust and compare summary statistics in order to test different assumptions and impacts on SNe Ia data. Among the SNe Ia-derived models, we find that a logistic function of the total-to-selective extinction |$R_V$| best recreates the correlations between supernova distance measurements and host galaxy properties, though an additional 0.02 mag of grey scatter is needed to fully explain the scatter in SNIa brightness in all cases. These empirically derived extinction distributions are highly incompatible with the physical attenuation models from galactic spectral measurements. From these results, we conclude that SNe Ia must either preferentially select extreme ends of galactic dust distributions, or that the characterization of dust along the SNe Ia line-of-sight is incompatible with that of galactic dust distributions. [ABSTRACT FROM AUTHOR]

We assess the usefulness of gradient-based samplers, such as the no-U-turn sampler (NUTS), by comparison with traditional Metropolis–Hastings (MH) algorithms, in tomographic |$3\times 2$| point analyses. Specifically, we use the Dark Energy Survey (DES) Year 1 data and a simulated dataset for the Large Synoptic Survey Telescope (LSST) survey as representative examples of these studies, containing a significant number of nuisance parameters (20 and 32, respectively) that affect the performance of rejection-based samplers. To do so, we implement a differentiable forward model using jax-cosmo , and we use it to derive parameter constraints from both data sets using the nuts algorithm implemented in numpyro , and the Metropolis–Hastings algorithm as implemented in cobaya. When quantified in terms of the number of effective number of samples taken per likelihood evaluation, we find a relative efficiency gain of |$\mathcal {O}(10)$| in favour of NUTS. However, this efficiency is reduced to a factor |$\sim 2$| when quantified in terms of computational time, since we find the cost of the gradient computation (needed by nuts) relative to the likelihood to be |$\sim 4.5$| times larger for both experiments. We validate these results making use of analytical multivariate distributions (a multivariate Gaussian and a Rosenbrock distribution) with increasing dimensionality. Based on these results, we conclude that gradient-based samplers such as NUTS can be leveraged to sample high-dimensional parameter spaces in Cosmology, although the efficiency improvement is relatively mild for moderate (⁠|$\mathcal {O}(50)$|⁠) dimension numbers, typical of tomographic large-scale structure analyses. [ABSTRACT FROM AUTHOR]

We present griz photometric light curves for the full 5 yr of the Dark Energy Survey Supernova (DES-SN) program, obtained with both forced point-spread function photometry on difference images (DiffImg) performed during survey operations, and scene modelling photometry (SMP) on search images processed after the survey. This release contains 31,636 DiffImg and 19,706 high-quality SMP light curves, the latter of which contain 1635 photometrically classified SNe that pass cosmology quality cuts. This sample spans the largest redshift (z) range ever covered by a single SN survey (0.1 < z < 1.13) and is the largest single sample from a single instrument of SNe ever used for cosmological constraints. We describe in detail the improvements made to obtain the final DES-SN photometry and provide a comparison to what was used in the 3 yr DES-SN spectroscopically confirmed Type Ia SN sample. We also include a comparative analysis of the performance of the SMP photometry with respect to the real-time DiffImg forced photometry and find that SMP photometry is more precise, more accurate, and less sensitive to the host-galaxy surface brightness anomaly. The public release of the light curves and ancillary data can be found at github.com/des-science/DES-SN5YR and doi: 10.5281/zenodo.12720777. [ABSTRACT FROM AUTHOR]

This paper proposes a new model for anisotropic compact stars with quintessence in Rastall teleparallel gravity via embedding approach. In the gravity, the acquired field equations encompassing the anisotropic matter source as well as the quintessence field are studied using the specific character of the scalar torsion T for the observed stars candidates PSRJ 1416–2230, 4U 1608–52, CenX–3, EXO 1785–248 and SMC X–1. All of the stellar structures under consideration are said to be advantageously independent of any central singularity and are stable. A thorough graphical analysis reveals that numerous physical properties critical for forming stellar structures are satisfied. [ABSTRACT FROM AUTHOR]

In this paper, we have explored cold dark matter and holographic dark energy cosmological model with big rip singularity. To obtain the solution of the field equation, we supposed that scalar expansion is proportional to shear scalar σ 2 , which leads to P 1 = (P 2) n , where P 1 , P 2 are metric potentials and n is constant. Big bang and big rip singularity are investigated. The state-finder parameter is analyzed. The physical and geometrical parameters of the universe are explained. [ABSTRACT FROM AUTHOR]

This work reports a study on bounce cosmology with a highly generalized holographic dark fluid inspired by Nojiri and Odintsov [Eur. Phys. J. C 77 (2017) 1–8]. The holographic dark fluid that is mostly used for late-time acceleration has been implemented to reconstruct toward realization of cosmological bounce. We first used the most generalized Nojiri–Odintsov (NO) cutoff to implement the holographic dark fluid. Accordingly, we have reconstructed this dark fluid via some solutions of scale factors. With those solutions, we have explored the evolution of different cosmological parameters. We have examined the effects of each reconstructed parameter in the context of the realization of the cosmic bounce. Next, we use the analytical inferences of the scalar spectral index, tensor-to-scalar ratio, and slow-roll characteristics of the model to study a bounce inflationary scenario. Since inflation is usually associated with the existence of scalar fields, we looked at a possible relationship between NO generalized holographic dark energy and scalar field models. Plotting the evolution of the potential results from the scalar fields against time. Finally, we investigated the GSL of thermodynamics in the pre- and post-bounce scenarios. [ABSTRACT FROM AUTHOR]

This paper considers the only sectors to constitute the present universe as the dark matter and dark energy. The proposed new agegraphic dark energy model studies the gradual transition from matter to dark energy in sequential order, including the current dominance of the matter sector by dark energy. The model utilizes concepts of Tsallis entropy and the Karolyhazy relation with conformal time η as the time scale. Various evolutionary aspects of the universe are characterized by Tsallis parameter δ and the model constant c. Expressions for dynamic behavior of dark energy, as a differential equation, equation of state and deceleration parameters are obtained to describe the thermal history of universe evolution. Also, the stability of the model is analyzed through squared sound speed parameter. The analysis is made by considering an interaction as well as independence among the constituent sectors of the universe. [ABSTRACT FROM AUTHOR]

In this paper, we consider the single-parameter ℛ+cℛ2 gravitational action and use constraints from astrophysics and the laboratory to derive a natural relation between the coefficient c and the value of the cosmological constant. We find that the renormalization of c from the energy of the inflationary phase to the infrared, where the acceleration of the expansion of the universe takes place, is correlated with the evolution of the vacuum energy. Our results suggest that the coefficient of the ℛ2 term may provide an unexpected bridge between high-energy physics and cosmological phenomena such as inflation and dark energy. [ABSTRACT FROM AUTHOR]

In [1], we pointed out that in the Dark Dimension scenario [2] theoretical issues arise when the prediction for the vacuum energy ρ, that is obtained from swampland conjectures in string theory, is confronted with the corresponding result for ρ in the effective field theory (EFT) limit. One of the problems concerns the widely spread belief that in higher dimensional EFTs with compact dimensions the vacuum energy is automatically finite. On the contrary, our analysis shows that ρ contains (previously missed) UV-sensitive terms. Our work was challenged in [3]. Here we show why in our opinion the claims in [3] are flawed, and provide further support to our findings. We conclude presenting ideas on the physical mechanism that should dispose of the large UV contributions to ρ. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of a new iterative density reconstruction algorithm. This algorithm uses a decreasing smoothing scale to better reconstruct the density field in Lagrangian space. We implement this algorithm to run on the quijote simulations, and extend it to (a) include a smoothing kernel that smoothly goes from anisotropic to isotropic, and (b) a variant that does not correct for redshift space distortions. We compare the performance of this algorithm with the standard reconstruction method. Our examinations of the methods include cross-correlation of the reconstructed density field with the linear density field, reconstructed two-point functions, and BAO parameter fitting. We also examine the impact of various parameters, such as smoothing scale, anisotropic smoothing, tracer type/bias, and the inclusion of second order perturbation theory. We find that the two reconstruction algorithms are comparable in most of the areas we examine. In particular, both algorithms give consistent fittings of BAO parameters. The fits are robust over a range of smoothing scales. We find the iterative algorithm is significantly better at removing redshift space distortions. The new algorithm will be a promising method to be employed in the ongoing and future large-scale structure surveys. [ABSTRACT FROM AUTHOR]

In this paper, our investigation focuses on the cosmic history in modified f(Q) gravity, a different theory that describes the gravitational force using a non-metricity scalar. The equations of the theory are solved by assuming a parametric form for the deceleration parameter. The parameters of the model are estimated by using the Cosmic Chronometer dataset. A number of parameters, like the deceleration parameter, whose signature changes with redshift and shows typical behavior in late-time cosmology, are subject of our analysis. We also show the evolution of other parameters, such as the equation of state parameter and energy density. The parametrization approach used here in f(Q) modified gravity provides a better description of the late-time cosmic evolution without dark energy. [ABSTRACT FROM AUTHOR]

In this paper, we deal with spacetimes allowing a semi-symmetric connection whose metric tensor is recurrent. We investigate the impact of this connection on spacetimes and establish a nontrivial example. We physically explain the properties of spacetime that we obtained. Under a certain condition, we demostrate that a spacetime admitting such a connection becomes the GRW spacetime as well as the anti-de Sitter and represents the dark matter era. Finally, we scrutinize in case such a spacetime admits a Ricci soliton and generalized Ricci soliton. [ABSTRACT FROM AUTHOR]

We explore the influence of radio-mode feedback on the properties of the cool circumgalactic medium (CGM). To this end, we assemble a statistical sample of approximately 30,000 radio galaxies with background quasars by combining optical spectroscopic measurements of luminous red galaxies and quasars from the year 1 data set of the Dark Energy Spectroscopic Instrument and radio sources from the LOw-Frequency ARray Two-metre Sky Survey (LoTSS) DR2 catalog and the Very Large Array Sky Survey (VLASS) quick-look catalog. Galaxies with similar optical properties but with no radio counterparts in LoTSS and VLASS are selected as the control group. We measure the cool CGM properties of radio galaxies and their control samples traced by Mg ii absorption lines, including covering fraction, rest equivalent width, and gas kinematics. Our results show no significant difference in the properties of gas around radio galaxies and their control sample, indicating that the operating radio-mode feedback of massive galaxies does not produce detectable effects on the properties of the cool CGM. Finally, we show that the CGM of radio galaxies contains a nonnegligible amount of cool gas with approximately 1010 M ⊙. This abundance can place a stringent constraint on the radio-mode feedback models. [ABSTRACT FROM AUTHOR]

Flux excesses in the early-time light curves of Type Ia supernovae (SNe Ia) are predicted by multiple theoretical models and have been observed in a number of nearby SNe Ia over the last decade. However, the astrophysical processes that cause these excesses may affect their use as standardizable candles for cosmological parameter measurements. We perform a systematic search for early-time excesses in SNe Ia observed by the Zwicky Transient Facility (ZTF) to study whether SNe Ia with these excesses yield systematically different Hubble residuals. We analyze two compilations of SN Ia light curves from ZTF's first year of operations: 127 high-cadence light curves from Y. Yao et al. and 305 light curves from the ZTF cosmology data release of S. Dhawan et al. We detect significant early-time excesses for 17 SNe Ia in these samples and find that the excesses have a median g − r color of 0.10 ± 0.11 mag; we do not find a clear preference for blue excesses as predicted by several models. Using the SALT3 model, we measure Hubble residuals for these two samples, finding that excess-having SNe Ia may have lower Hubble residuals (HR) after correcting for shape, color, and host-galaxy mass, at ∼2–3 σ significance; our baseline result is ΔHR = −0.056 ± 0.026 mag (2.2 σ). We compare the host-galaxy masses of excess-having and no-excess SNe Ia and find they are consistent, though at marginal significance excess-having SNe Ia may prefer lower-mass hosts. Additional discoveries of early excess SNe Ia will be a powerful way to understand potential biases in SN Ia cosmology and probe the physics of SN Ia progenitors. [ABSTRACT FROM AUTHOR]

In the emerging era of big data astrophysics, large-scale extragalactic surveys will soon provide high-quality imaging for billions of celestial objects to answer major questions in astrophysics such as the nature of dark matter and dark energy. Precision cosmology with surveys requires accurate photometric redshift (photo- z) estimation with well-constrained uncertainties as inputs for weak lensing models to measure cosmological parameters. Machine learning methods have shown promise in optimizing the information gained from galaxy images in photo- z estimation; however, many of these methods are limited in their ability to estimate accurate uncertainties. In this work, we present one of the first applications of Bayesian convolutional neural networks (BCNNs) for photo- z estimation and uncertainties. In addition, we use conformal mapping to calibrate the photo- z uncertainties to achieve good statistical coverage. We use the public GalaxiesML data set of ∼300k galaxies from the Hyper Suprime-Cam survey containing five-band photometric images and known spectroscopic redshifts from 0 < z < 4. We find that the performance is much improved when using images compared to photometry, with the BCNN achieving 0.098 rms error, a standard outlier rate of 3.9%, a 3 σ outlier rate of 4.5%, and a bias of 0.0007. The performance drops significantly beyond z > 1.5 due to the relative lack of training data beyond those redshifts. This investigation demonstrates the power of using images directly and we advocate that future photo- z analysis of large-scale surveys include galaxy images. [ABSTRACT FROM AUTHOR]

In the Emergent scenario, the Universe should evolve from a nonsingular state replacing the typical singularity of General Relativity, for any initial condition. For the scalar field model by Ellis and Maartens [Class. Quantum Grav. 21 (2003) 223] we show that only a set of measure zero of trajectories leads to emergence, either from a static state (an Einstein model), or from a de Sitter state. Assuming a scenario based on CDM interacting with a Dark Energy fluid, we show that in general flat and open models expand from a nonsingular unstable de Sitter state at high energies; for some closed models this state is a transition phase with a bounce, other closed models are cyclic. A subset of these models are qualitatively in agreement with the observable Universe, accelerating at high energies, going through a matter-dominated decelerated era, then accelerating toward a de Sitter phase. [ABSTRACT FROM AUTHOR]

Extracting precise cosmology from weak lensing surveys requires modelling the non-linear matter power spectrum, which is suppressed at small scales due to baryonic feedback processes. However, hydrodynamical galaxy formation simulations make widely varying predictions for the amplitude and extent of this effect. We use measurements of Dark Energy Survey Year 3 weak lensing (WL) and Atacama Cosmology Telescope DR5 kinematic Sunyaev–Zel'dovich (kSZ) to jointly constrain cosmological and astrophysical baryonic feedback parameters using a flexible analytical model, 'baryonification'. First, using WL only, we compare the |$S_8$| constraints using baryonification to a simulation-calibrated halo model, a simulation-based emulator model, and the approach of discarding WL measurements on small angular scales. We find that model flexibility can shift the value of |$S_8$| and degrade the uncertainty. The kSZ provides additional constraints on the astrophysical parameters, with the joint WL + kSZ analysis constraining |$S_8=0.823^{+0.019}_{-0.020}$|⁠. We measure the suppression of the non-linear matter power spectrum using WL + kSZ and constrain a mean feedback scenario that is more extreme than the predictions from most hydrodynamical simulations. We constrain the baryon fractions and the gas mass fractions and find them to be generally lower than inferred from X-ray observations and simulation predictions. We conclude that the WL + kSZ measurements provide a new and complementary benchmark for building a coherent picture of the impact of gas around galaxies across observations. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive overview of how fitting of baryon acoustic oscillations (BAO) is carried out within the upcoming Dark Energy Spectroscopic Instrument's (DESI) 2024 results using its DR1 data set, and the associated systematic error budget from theory and modelling of the BAO. We derive new results showing how non-linearities in the clustering of galaxies can cause potential biases in measurements of the isotropic (⁠|$\alpha _{\mathrm{iso}}$|⁠) and anisotropic (⁠|$\alpha _{\mathrm{ap}}$|⁠) BAO distance scales, and how these can be effectively removed with an appropriate choice of reconstruction algorithm. We then demonstrate how theory leads to a clear choice for how to model the BAO and develop, implement, and validate a new model for the remaining smooth-broad-band (i.e. without BAO) component of the galaxy clustering. Finally, we explore the impact of all remaining modelling choices on the BAO constraints from DESI using a suite of high-precision simulations, arriving at a set of best practices for DESI BAO fits, and an associated theory and modelling systematic error. Overall, our results demonstrate the remarkable robustness of the BAO to all our modelling choices and motivate a combined theory and modelling systematic error contribution to the post-reconstruction DESI BAO measurements of no more than 0.1 per cent (0.2 per cent) for its isotropic (anisotropic) distance measurements. We expect the theory and best practices laid out to here to be applicable to other BAO experiments in the era of DESI and beyond. [ABSTRACT FROM AUTHOR]

Bounce cosmological models containing a dark viscous fluid in a spatially flat Friedmann–Robertson–Walker (FRW) universe are considered. The universe’s evolution is described in terms of generalized equation of state (EoS) parameters, in the presence of the bulk viscosity. Entropic cosmology plays a key role in the discussion, and the matter bounce behavior is described based on a nonsingular, generalized entropy function, recently proposed by S. D. Odintsov and T. Paul. Three different forms of the scale factor are investigated: an exponential, a power-law and a double-exponential function, respectively. Appropriate bounce cosmological models are formulated, via the relevant parameters of the modified EoS, and analytical expressions for the corresponding infrared cut-off are obtained, via the particle horizon. Results are displayed in holographic form, making use of generalized holographic cut-offs first introduced by S. Nojiri and S. D. Odintsov. In addition, the viability of the corresponding bounce cosmological models is investigated, taking into account the actual thermodynamic properties of our universe, by means of a no-singular, generalized entropy function. In the asymptotic case, an expression for the generalized entropy is obtained, which remarkably has the additivity property. [ABSTRACT FROM AUTHOR]

According to the “dark dimension” (DD) scenario, we might live in a universe with a single compact extra dimension, whose mesoscopic size is dictated by the measured value of the cosmological constant. This scenario is based on swampland conjectures that lead to the relation ρswamp ∼ mKK4 between the vacuum energy ρswamp and the size of the extra dimension mKK−1 (mKK is the mass scale of a Kaluza–Klein tower), and on the corresponding result ρEFT from the effective field theory (EFT) limit. We show that ρEFT contains previously missed UV-sensitive terms, whose presence invalidates the widely spread belief (based on existing literature) that the calculation gives automatically the finite result ρEFT ∼ mKK4 (with no need for fine-tuning). This renders the matching between ρswamp and ρEFT a nontrivial issue. We then comment on the necessity to find a mechanism that implements the suppression of the aforementioned UV-sensitive terms. This should finally allow to frame the DD scenario in a self-consistent framework, also in view of its several phenomenological applications based on EFT calculations. [ABSTRACT FROM AUTHOR]

The editorial discusses recent observational data indicating that the cosmic expansion is accelerating, with dark energy and dark matter comprising a significant portion of the universe's energy density. Various telescopes and satellites are expected to provide further insights into modern cosmology. The text also explores different theories to explain the accelerated expansion, including dark energy and extended theories of gravitation. Additionally, the editorial highlights important subjects in modern cosmology, such as physics in the early universe, dark matter, and gravitational waves. [Extracted from the article]

We perform observational confrontation and cosmographic analysis of f (T , T G) gravity and cosmology. This higher-order torsional gravity is based on both the torsion scalar, as well as on the teleparallel equivalent of the Gauss–Bonnet combination, and gives rise to an effective dark-energy sector which depends on the extra torsion contributions. We employ observational data from the Hubble function and supernova Type Ia Pantheon datasets, applying a Markov chain Monte Carlo sampling technique, and we provide the iso-likelihood contours, as well as the best-fit values for the parameters of the power-law model, an ansatz which is expected to be a good approximation of most realistic deviations from general relativity. Additionally, we reconstruct the effective dark-energy equation-of-state parameter, which exhibits a quintessence-like behavior, while in the future the Universe enters into the phantom regime, before it tends asymptotically to the cosmological constant value. Furthermore, we perform a detailed cosmographic analysis, examining the deceleration, jerk, snap, and lerk parameters, showing that the transition to acceleration occurs in the redshift range 0.52 ≤ z t r ≤ 0.89 , as well as the preference of the scenario for quintessence-like behavior. Finally, we apply the Om diagnostic analysis to cross-verify the behavior of the obtained model. [ABSTRACT FROM AUTHOR]

This study is about the consequences of fermionic q-deformation on Friedmann equations and its effects on cosmology within the framework of Verlinde’s entropic gravity proposal. We begin by examining the thermodynamic properties of q-deformed fermion gas model in two-dimensional space. We then extend our research to derive modified Friedmann equations using the Friedmann-Robertson-Walker (FRW) metric to study cosmological dynamics using q-deformed MOND theory. The study describes the effective energy density, pressure, and equation of state of dark energy within this modified framework. Finally, by providing an analytical expression for the effective density parameter of dark energy, we provide valuable insights into the interaction between quantum deformation and cosmological events. [ABSTRACT FROM AUTHOR]

The Regular Phantom Black Hole (RPBH)s are of theoretical and observational importance, some of their properties have been studied. In this work, some of thermodynamical properties such as entropy, temperature, etc., in three background cases, that is, flat, de–Sitter (dS) and Anti–de Sitter (AdS) are studied. Many of the RPBH properties, including horizon radius, are (directly or indirectly) dependent on a scale parameter b$b$. Due to the slightly different structure from Schwarzschild—like metrics, the method to express relations between thermodynamical variables requires a new function of the scale parameter. The local and global stability through the Heat Capacity (HC) and Gibbs free Energy (GE), respectively are also treated. In the AdS case, the regularized metric allows a Hawking‐Page like phase transition of first order. The calculations and graphs show the results in the flat background, are very similar to Schwarzschild black hole and the asymptotically AdS RPBH is more compatible with physical laws than the dS and flat backgrounds. [ABSTRACT FROM AUTHOR]

The authors show that in the f(Q)$f(Q)$ gravity with a non‐metricity scalar Q$Q$, the curvatures in Einstein's gravity, that is, the Riemann curvature constructed from the standard Levi‐Civita connection, could not be excluded or naturally appear. The first observation is that even in f(Q)$f(Q)$ gravity, the conservation of the matter energy‐momentum tensor is not described by the covariant derivatives in the non‐metricity gravity but that is given by the Levi‐Civita connection. The commutator of the covariant derivatives in Einstein's gravity inevitably induces the Riemann curvature. There is no symmetry nor principle which prohibits the Riemann curvature in non‐metricity gravity. Based on this observation, the authors propose and investigate fQ,G$f\left(Q, \mathcal {G} \right)$ gravity with the Gauss–Bonnet invariant G$\mathcal {G}$ and its generalizations. The authors also show how fQ,G$f\left(Q, \mathcal {G} \right)$ models realizing any given the Friedmann–Lemaître–Robertson– Walker (FLRW) spacetime can be reconstructed. The reconstruction formalism to cosmology is applied. Explicitly, the gravity models which realize slow roll or constant roll inflation, dark energy epoch as well as the unification of the inflation and dark energy are found. The dynamical autonomous system and the gravitational wave in the theory under investigation are discussed. It is found the condition that the de Sitter spacetime becomes the (stable) fixed point of the system. We show that in the f(Q)$f(\mathcal{Q})$ gravity with a non‐metricity scalar Q$Q$, the curvatures in Einstein's gravity, that is, the Riemann curvature constructed from the standard Levi‐Civita connection, could not be excluded or naturally appear. The first observation is that even in f(Q)$f(\mathcal{Q})$ gravity, the conservation of the matter energy‐momentum tensor is not described by the covariant derivatives in the non‐metricity gravity but that is given by the Levi‐Civita connection. The commutator of the covariant derivatives in Einstein's gravity inevitably induces the Riemann curvature. There is no symmetry nor principle which prohibits the Riemann curvature in non‐metricity gravity. Based on this observation, we propose and investigate f(Q,G)$f({\mathcal{Q},\mathcal{G}})$ gravity with the Gauss–Bonnet invariant G$\mathcal{G}$ and its generalisations. We show how f(Q,G)$f({\mathcal{Q},\mathcal{G}})$ models realising any given the Friedmann–Lemaître–Robertson– Walker (FLRW) spacetime can be reconstructed. We apply the reconstruction formalism to cosmology. Explicitly, the gravity models which realise slow roll or constant roll inflation, dark energy epoch as well as the unification of the inflation and dark energy are found. The dynamical autonomous system and the gravitational wave in the theory under investigation are discussed. It is found the condition that the de Sitter spacetime becomes the (stable) fixed point of the system. [ABSTRACT FROM AUTHOR]

We propose a toy model of a spherical universe made up of an exotic dark gas with temperature T in thermal equilibrium with a black body in adiabatic expansion. Each particle of this exotic gas mimics a kind of particle of dark energy represented by the vacuum energy, being quantized into virtual particles with extremely small masses that form such gas representing the own tissue of the expanding space–time governed by a negative pressure whose origin is the equation of state of vacuum, i.e., p = −ρ, where ρ is the vacuum energy density. So, each vacuum particle occupies a tiny area of space so-called Planck area L p 2 , which represents the minimum area of the whole space–time given by the spherical surface with area 4 π R H 2 , where RH is the Hubble radius. We realize that such spherical surface is the surface of the black body for representing the dark universe as if it were the surface of an expanding balloon. Thus, we are able to derive the law of universal gravitation, thus leading us to understand the cosmological anti-gravity. We estimate the very small order of magnitude of the cosmological constant and the acceleration of expansion of the dark sphere. In this toy model, as the dark universe can be thought of as a large black body, when we obtain its power and frequency of emission of radiation, we find very low values. We conclude that such radiation and frequency of the black body made up of dark energy is a background gravitational wave with very low frequency in the order of 10−17Hz due to the slight stretching of the fabric of space–time. [ABSTRACT FROM AUTHOR]

The present work investigates a new model of the gravastar in a framework of 5-Dimensional (5D) Einstein-Gauss-Bonnet (EGB) gravitational theory. Adopting the approach of Mazur and Mottala (Proc. Natl. Acad. Sci., 101, 9545–9550, 2001, 2004) we divide the geometry of the stellar spherical object into three different portions, as follows (i) interior portion (ii) intermediate spherical thin shell and (iii) exterior portion. The interior portion contains dark energy having negative pressure. The thin shell region is made up of ultra-relativistic plasma where pressure and energy density are directly proportional. The exterior portion is completely vacuumed. By considering these assumptions, a set of stable and non-singular exact solutions for a gravastar has been investigated. In our model, graphical behavior shows that the obtained solution is physically reasonable and interesting. [ABSTRACT FROM AUTHOR]

We present a method for modelling the cluster–galaxy correlation function in redshift space, down to |$\sim$| Mpc scales. The method builds upon the so-called galaxy infall kinematics (GIK) model, a parametric model for the pairwise velocities of galaxies with respect to nearby galaxy clusters. We fit the parameters of the GIK model to a suite of simulations run with different cosmologies, and use Gaussian processes to emulate how the GIK parameters depend upon cosmology. This emulator can then be combined with knowledge of the real-space clustering of clusters and galaxies, to predict the cluster–galaxy correlation function in redshift space, |$\xi _\mathrm{cg}^s$|⁠. Fitting this model to an observed |$\xi _\mathrm{cg}^s$| enables the extraction of cosmological parameter constraints, and we present forecasts for a survey like that currently being done by the Dark Energy Spectroscopic Instrument (DESI). We also perform tests of the robustness of our constraints from fitting to mock data extracted from N -body simulations, finding that fitting to scales |$\lesssim 3 \, h^{-1}\, \mathrm{Mpc}$| leads to a biased inference on cosmology, due to model mis-specification on these scales. Finally, we discuss what steps will need to be taken in order to apply our method to real data. [ABSTRACT FROM AUTHOR]

JWST has revealed a large population of UV-bright galaxies at |$z\gtrsim 10$| and possibly overly massive galaxies at |$z\gtrsim 7$|⁠ , challenging standard galaxy formation models in the ΛCDM cosmology. We use an empirical galaxy formation model to explore the potential of alleviating these tensions through an Early Dark Energy (EDE) model, originally proposed to solve the Hubble tension. Our benchmark model demonstrates excellent agreement with the UV luminosity functions (UVLFs) at |$4\lesssim z \lesssim 10$| in both ΛCDM and EDE cosmologies. In the EDE cosmology, the UVLF measurements at |$z\simeq 12$| based on spectroscopically confirmed galaxies (eight galaxies at |$z\simeq 11\!-\!13.5$|⁠) exhibit no tension with the benchmark model. Photometric constraints at |$12 \lesssim z\lesssim 16$| can be fully explained within EDE via either moderately increased star-formation efficiencies (⁠|$\epsilon _{\ast}\sim 3\!-\!10\ \hbox{per cent}$| at |$M_{\rm halo}\sim 10^{10.5}{\, \rm M_\odot }$|⁠) or enhanced UV variabilities (⁠|$\sigma _{\rm UV}\sim 0.8\!-\!1.3$|  mag at |$M_{\rm halo}\sim 10^{10.5}{\, \rm M_\odot }$|⁠) that are within the scatter of hydrodynamical simulation predictions. A similar agreement is difficult to achieve in |$\Lambda$| CDM, especially at |$z\gtrsim 14$|⁠ , where the required |$\sigma _{\rm UV}$| exceeds the maximum value seen in simulations. Furthermore, the implausibly large cosmic stellar mass densities inferred from some JWST observations are no longer in tension with cosmology when the EDE is considered. Our findings highlight EDE as an intriguing unified solution to a fundamental problem in cosmology and the recent tensions raised by JWST observations. Data at the highest redshifts reached by JWST will be crucial for differentiating modified galaxy formation physics from new cosmological physics. [ABSTRACT FROM AUTHOR]

A theoretical investigation is presented for the bright and dark solitons in GaAs, GaSb, InP, and GaN quantum magnetized semiconductor plasma systems. The plasma system consists of electrons, holes, and ions, all existed in a quantizing magnetic field. The Zakharov–Kuznetsov (ZK) equation is derived by using the reductive perturbation method. The bright and the dark soliton solutions are derived for the ZK equation. The electric field and the soliton energy were also derived. The present results are considered to be beneficial in understanding the waves propagating in quantum semiconductor plasmas on an ultrafast time scale in semiconductors nanostructures that are applicable for quantum computing. [ABSTRACT FROM AUTHOR]

This paper is an investigation of dark energy cosmological models in non-coincident gauge formulation of non-metricity gravity with boundary term. We have considered an arbitrary function f (Q , C) = Q + λ C m , where Q is the non-metricity scalar, C is the boundary term derived by C = R ˚ − Q , and λ , m are the model parameters, to obtain the modified field equations from action. We have parameterized the Hubble function as H (a) = k 0 (a (t) − n + k 1) with n , k 0 , k 1 are arbitrary constants and a (t) is the scale-factor depending upon cosmic time. We have compared this Hubble function with H (z) datasets and obtained best fit values of model parameters using likelihood analysis. Using these best fit values of model parameters, we have done our result analysis and discussion with cosmological parameters viz effective equation of state parameter, energy density, energy conditions, deceleration parameter, om diagnostic analysis and age of the universe. We have found a transit phase universe model with effective EoS parameter − 1. 1 8 < ω eff < − 0. 2 over redshift − 1 < z < 3. [ABSTRACT FROM AUTHOR]

This research investigates the impact of modified gravity on cosmic scales, focusing on f (Q) cosmology. By applying energy conditions, the study reconstructs various f (Q) models, considering an accelerating Universe, quintessence, and a cosmological constant Λ. Using up-to-date observational data, including the Supernova Pantheon sample and cosmic chronometer data, Hubble constants H 0 are estimated as 7 0. 3 7 − 0. 9 2 + 0. 8 4 km/s/Mpc (from H (z) data) and 7 0. 0 2 − 0. 2 5 + 0. 4 4 km/s/Mpc (from pantheon compilation of SN Ia data). The matter energy density parameter ( Ω 0 m ) is calculated as 0. 2 6 − 0. 0 1 0 0. 0 1 5 (OHD) and 0. 2 7 − 0. 0 1 4 0. 0 2 5 (SN Ia). Furthermore, as a function of red-shift z , explicit expressions of f (Q) and the EOS parameter ω are produced, and their graphical analysis describes the late time acceleration of the Universe without the usage of dark energy. [ABSTRACT FROM AUTHOR]

We investigate the physical measurability of the infrared instability of a de Sitter phase in the formalism recently proposed. We find that the logarithmic decay of the effective cosmological constant is only measurable if an additional clock field is introduced. [ABSTRACT FROM AUTHOR]