Search

We present a precise measurement of cosmological time dilation using the light curves of 1504 Type Ia supernovae from the Dark Energy Survey spanning a redshift range |$0.1\lesssim z\lesssim 1.2$|⁠. We find that the width of supernova light curves is proportional to |$(1+z)$|⁠ , as expected for time dilation due to the expansion of the Universe. Assuming Type Ia supernovae light curves are emitted with a consistent duration |$\Delta t_{\rm em}$|⁠ , and parametrizing the observed duration as |$\Delta t_{\rm obs}=\Delta t_{\rm em}(1+z)^b$|⁠ , we fit for the form of time dilation using two methods. First, we find that a power of |$b \approx 1$| minimizes the flux scatter in stacked subsamples of light curves across different redshifts. Secondly, we fit each target supernova to a stacked light curve (stacking all supernovae with observed bandpasses matching that of the target light curve) and find |$b=1.003\pm 0.005$| (stat) |$\pm \, 0.010$| (sys). Thanks to the large number of supernovae and large redshift-range of the sample, this analysis gives the most precise measurement of cosmological time dilation to date, ruling out any non-time-dilating cosmological models at very high significance. [ABSTRACT FROM AUTHOR]

We have obtained Integral Field Unit (IFU) spectra of 75 Type Ia supernova (SN Ia) host galaxies from the Foundation Supernova Survey to search for correlations between the properties of individual galaxies and SN Hubble residuals. After standard corrections for light-curve width and SN colour have been applied, we find correlations between Hubble residuals and the equivalent width (EW) of the [ |${\rm O\, {\small II}}$| ] |$\lambda \lambda$| 3727, 3729 doublet (2.3 |$\sigma$|⁠), an indicator of the specific star formation rate. When splitting our sample by SN colour, we find no colour dependence impacting the correlation between EW[ |${\rm O\, {\small II}}$| ] and Hubble residual. However, when splitting by colour, we reveal a correlation between the Hubble residuals of blue SNe Ia and the Balmer decrement (2.2 |$\sigma$|⁠), an indicator of dust attenuation. These correlations remain after applying a mass-step correction, suggesting that the mass-step correction does not fully account for the limitations of the colour correction used to standardize SNe Ia. Rather than a mass correction, we apply a correction to SNe from star-forming galaxies based on their measurable EW[ |${\rm O\, {\small II}}$| ]. We find that this correction also removes the host galaxy mass-step, while also greatly reducing the significance of the correlation with the Balmer decrement for blue SNe Ia. We find that correcting for EW[ |${\rm O\, {\small II}}$| ], in addition to or in place of the mass-step, may further reduce the scatter in the Hubble diagram. [ABSTRACT FROM AUTHOR]

We report constraints on a variety of non-standard cosmological models using the full 5-yr photometrically classified type Ia supernova sample from the Dark Energy Survey (DES-SN5YR). Both Akaike Information Criterion (AIC) and Suspiciousness calculations find no strong evidence for or against any of the non-standard models we explore. When combined with external probes, the AIC and Suspiciousness agree that 11 of the 15 models are moderately preferred over Flat- |$\Lambda$| CDM suggesting additional flexibility in our cosmological models may be required beyond the cosmological constant. We also provide a detailed discussion of all cosmological assumptions that appear in the DES supernova cosmology analyses, evaluate their impact, and provide guidance on using the DES Hubble diagram to test non-standard models. An approximate cosmological model, used to perform bias corrections to the data holds the biggest potential for harbouring cosmological assumptions. We show that even if the approximate cosmological model is constructed with a matter density shifted by |$\Delta \Omega _{\rm m}\sim 0.2$| from the true matter density of a simulated data set the bias that arises is subdominant to statistical uncertainties. Nevertheless, we present and validate a methodology to reduce this bias. [ABSTRACT FROM AUTHOR]

Reconstructing the intrinsic Ly  |$\alpha$| line flux from high- z QSOs can place constraints on the neutral hydrogen content of the intergalactic medium during reionization. There are now |$\gtrsim 10$| different Ly  |$\alpha$| reconstruction pipelines using different methodologies to predict the Ly  |$\alpha$| line flux from correlations with the spectral information redwards of Ly  |$\alpha$|⁠. However, there have been few attempts to directly compare the performance of these pipelines. Therefore, we devised a blind QSO challenge to compare these reconstruction pipelines on a uniform set of objects. Each author was provided de-identified, observed rest-frame QSO spectra with spectral information only redwards of 1260 Å rest-frame to ensure unbiased reconstruction. We constructed two samples of 30 QSOs, from X-Shooter and Sloan Digital Sky Survey (SDSS) both spanning |$3.5\lt z\lt 4.5$|⁠. Importantly, the purpose of this comparison study was not to champion a single, best-performing reconstruction pipeline but rather to explore the relative performance of these pipelines over a range of QSOs with broad observational characteristics to infer general trends. In summary, we find machine-learning approaches in general provide the strongest 'best guesses' but underestimate the accompanying statistical uncertainty, although these can be recalibrated, while pipelines that decompose the spectral information, for example principal component or factor analysis, generally perform better at predicting the Ly  |$\alpha$| profile. Further, we found that reconstruction pipelines trained on SDSS QSOs performed similarly on average for both the X-Shooter and SDSS samples indicating no discernible biases owing to differences in the observational characteristics of the training set or QSO being reconstructed, although the recovered distributions of reconstructions for X-Shooter were broader likely due to an increased fraction of outliers. [ABSTRACT FROM AUTHOR]

We report measurements of the galaxy two-point correlation function at cosmic dawn, using photometrically selected sources from the JWST Advanced Deep Extragalactic Survey (JADES). The JWST/NIRCam data set comprises approximately |$N_g \simeq 7000$| photometrically selected Lyman Break Galaxies (LBGs), spanning in the redshift range |$5\le z\lt 11$|⁠. The primary objective of this study is to extend clustering measurements beyond redshift |$z\gt 10$|⁠ , finding a galaxy bias |$b=9.6\pm 1.7$| for the sample at |$\overline{z} = 10.6$|⁠. The result suggests that the observed sources are hosted by dark matter haloes of approximately |$M_{h}\sim 10^{10.6}~\mathrm{{\rm M}_{\odot }}$|⁠ , in broad agreement with theoretical and numerical modelling of early galaxy formation during the epoch of reionization. Furthermore, the JWST JADES data set enables an unprecedented investigation of clustering of dwarf galaxies two orders of magnitude fainter than the characteristic |$L_*$| luminosity (i.e. with |$M_{F200W}\simeq -15.8$|⁠) during the late stages of the epoch of reionization at |$z\sim 6$|⁠. By analysing clustering as a function of luminosity, we find that |$b(M_{F200W})$| aligns with previous results for brighter galaxies and then decreases with |$M_{F200W}$|⁠ , as theoretically expected for fainter candidates. These initial results demonstrate the potential for further quantitative characterization of the interplay between assembly of dark matter and light during cosmic dawn that the growing samples of JWST observations are enabling. [ABSTRACT FROM AUTHOR]

The most recent SH0ES measurement of the Hubble constant employs corrections of type Ia supernova magnitudes due to extinction in their host galaxies. These corrections are estimated using a probabilistic model which is trained on Hubble flow (⁠|$z\gt 0.03$|⁠) supernovae and extrapolated to the calibration galaxies (those with observed Cepheids), despite the fact that the latter are selected based on criteria favouring discy and dust-rich systems. We show that this standard approach underestimates the brightness of reddened supernovae in the high stellar-mass (⁠|$M_{\star }\gt 10^{10}\, \mathrm{M}_{\odot }$|⁠) calibration galaxies. This can be traced back to the fact that for these galaxies, a low total-to-selective extinction coefficient (⁠|$R_{\rm B}\sim 3$|⁠) is assumed, while for the low stellar-mass analogues a more standard |$R_{\rm B}\sim 4$| is adopted. We propose a minimalistic modification of the extinction model in the calibration galaxies in order to alleviate this systematic effect. The modification is twofold and it involves: (i) the same, Milky Way-like distribution of |$R_{\rm B}$| (with mean |$R_{\rm B}$| of 4.3 – consistent with the extinction curve used for colour corrections of the Cepheids – and scatter 0.4) and (ii) a modified shape of the |$E(B-V)$| reddening distribution while keeping the same effective slope of the supernova peak magnitude–colour relation and the same mean |$E(B-V)$| reddening as measured for supernovae in the Hubble flow. We show that this new approach yields a significantly better fit (⁠|$\Delta \mathrm{ BIC}=-11$|⁠) to the calibration data and results in a lower value of |$H_{0}$|⁠. Our result is |$H_{0}=70.5\pm 1$|  km s |$^{-1}$|  Mpc |$^{-1}$| implying a reduction of the Hubble constant tension from |$5.2\sigma$| to |$2.8\sigma$|⁠. [ABSTRACT FROM AUTHOR]

Current and future Type Ia Supernova (SN Ia) surveys will need to adopt new approaches to classifying SNe and obtaining their redshifts without spectra if they wish to reach their full potential. We present here a novel approach that uses only photometry to identify SNe Ia in the 5-yr Dark Energy Survey (DES) data set using the SuperNNova classifier. Our approach, which does not rely on any information from the SN host-galaxy, recovers SNe Ia that might otherwise be lost due to a lack of an identifiable host. We select |$2{,}298$| high-quality SNe Ia from the DES 5-yr data set an almost complete sample of detected SNe Ia. More than 700 of these have no spectroscopic host redshift and are potentially new SNIa compared to the DES-SN5YR cosmology analysis. To analyse these SNe Ia, we derive their redshifts and properties using only their light curves with a modified version of the SALT2 light-curve fitter. Compared to other DES SN Ia samples with spectroscopic redshifts, our new sample has in average higher redshift, bluer and broader light curves, and fainter host-galaxies. Future surveys such as LSST will also face an additional challenge, the scarcity of spectroscopic resources for follow-up. When applying our novel method to DES data, we reduce the need for follow-up by a factor of four and three for host-galaxy and live SN, respectively, compared to earlier approaches. Our novel method thus leads to better optimization of spectroscopic resources for follow-up. [ABSTRACT FROM AUTHOR]

Multiple observations now suggest that the hydrogen reionization may have ended well below redshift six. While there has previously been no conclusive proof of extended neutral islands in the |$z \lt 6$| intergalactic medium, it is possible that such islands give rise to the giant Ly  |$\alpha$| absorption troughs seen in the spectra of high-redshift quasars. Here, we present evidence that the deepest and longest known Ly  |$\alpha$| trough at |$z \,\lt\, 6$|⁠ , towards ULAS J0148 + 0600 (J0148), is associated with damping wing absorption. The evidence comes from a window of strong Ly  |$\alpha$| transmission at the edge of the J0148 proximity zone. We show that the relatively smooth profile of this transmission window is highly unlikely to arise from resonant absorption alone, but is consistent with the presence of a damping wing. We further argue that the damping wing is unlikely to arise from a compact source due to the lack of associated metal lines, and is more likely to arise from an extended neutral island associated with the giant Ly  |$\alpha$| trough. We investigate the physical conditions that may give rise to the strong transmission window, and speculate that it may signal an usually deep void, nearby ionizing sources, and/or the recent passage of an ionization front. [ABSTRACT FROM AUTHOR]

The most recent SH0ES measurement of the Hubble constant employs corrections of type Ia supernova magnitudes due to extinction in their host galaxies. These corrections are estimated using a probabilistic model which is trained on Hubble flow (⁠|$z\gt 0.03$|⁠) supernovae and extrapolated to the calibration galaxies (those with observed Cepheids), despite the fact that the latter are selected based on criteria favouring discy and dust-rich systems. We show that this standard approach underestimates the brightness of reddened supernovae in the high stellar-mass (⁠|$M_{\star }\gt 10^{10}\, \mathrm{M}_{\odot }$|⁠) calibration galaxies. This can be traced back to the fact that for these galaxies, a low total-to-selective extinction coefficient (⁠|$R_{\rm B}\sim 3$|⁠) is assumed, while for the low stellar-mass analogues a more standard |$R_{\rm B}\sim 4$| is adopted. We propose a minimalistic modification of the extinction model in the calibration galaxies in order to alleviate this systematic effect. The modification is twofold and it involves: (i) the same, Milky Way-like distribution of |$R_{\rm B}$| (with mean |$R_{\rm B}$| of 4.3 – consistent with the extinction curve used for colour corrections of the Cepheids – and scatter 0.4) and (ii) a modified shape of the |$E(B-V)$| reddening distribution while keeping the same effective slope of the supernova peak magnitude–colour relation and the same mean |$E(B-V)$| reddening as measured for supernovae in the Hubble flow. We show that this new approach yields a significantly better fit (⁠|$\Delta \mathrm{ BIC}=-11$|⁠) to the calibration data and results in a lower value of |$H_{0}$|⁠. Our result is |$H_{0}=70.5\pm 1$|  km s |$^{-1}$|  Mpc |$^{-1}$| implying a reduction of the Hubble constant tension from |$5.2\sigma$| to |$2.8\sigma$|⁠. [ABSTRACT FROM AUTHOR]

Recent quasar absorption line observations suggest that reionization may end as late as |$z \approx 5.3$|⁠. As a means to search for large neutral hydrogen islands at |$z\ \lt\ 6$|⁠ , we revisit long dark gaps in the Ly  |$\beta$| forest in Very Large Telescope/X-Shooter and Keck/Echellette Spectrograph and Imager quasar spectra. We stack the Ly  |$\alpha$| forest corresponding to both edges of these Ly  |$\beta$| dark gaps and identify a damping wing-like extended absorption profile. The average redshift of the stacked forest is |$z=5.8$|⁠. By comparing these observations with reionization simulations, we infer that such a damping wing-like feature can be naturally explained if these gaps are at least partially created by neutral islands. Conversely, simulated dark gaps lacking neutral hydrogen struggle to replicate the observed damping wing features. Furthermore, this damping wing-like profile implies that the volume-averaged neutral hydrogen fraction must be |$\langle x_{\rm H\,{\small {I}}} \rangle \ge 6.1 \pm 3.9~{{\ \rm per\ cent}}$| at |$z = 5.8$|⁠. Our results offer robust evidence that reionization extends below |$z=6$|⁠. [ABSTRACT FROM AUTHOR]

In the context of the cosmological and constrained Exploring the Local Universe with the reConstructed Initial Density field (ELUCID) simulation, this study explores the statistical characteristics of filaments within the cosmic web, focussing on aspects such as the distribution of filament lengths and their radial density profiles. Using the classification of the cosmic web environment through the Hessian matrix of the density field, our primary focus is on how cosmic structures react to the two variables |$R_{\rm s}$| and |$\lambda _{\rm th}$|⁠. The findings show that the volume fractions of knots, filaments, sheets, and voids are highly influenced by the threshold parameter |$\lambda _{\rm th}$|⁠ , with only a slight influence from the smoothing length |$R_{\rm s}$|⁠. The central axis of the cylindrical filament is pinpointed using the medial-axis thinning algorithm of the COsmic Web Skeleton (COWS) method. It is observed that median filament lengths tend to increase as the smoothing lengths increase. Analysis of filament length functions at different values of |$R_{\rm s}$| indicates a reduction in shorter filaments and an increase in longer filaments as |$R_{\rm s}$| increases, peaking around |$2.5R_{\rm s}$|⁠. The study also shows that the radial density profiles of filaments are markedly affected by the parameters |$R_{\rm s}$| and |$\lambda _{\rm th}$|⁠ , showing a valley at approximately |$2R_{\rm s}$|⁠ , with increases in the threshold leading to higher amplitudes of the density profile. Moreover, shorter filaments tend to have denser profiles than their longer counterparts. [ABSTRACT FROM AUTHOR]

Analyses of cosmic shear typically condense weak lensing information over a range of scales to a single cosmological parameter, |$S_8$|⁠. This paper presents a method to extract more information from Stage IV cosmic shear measurements by directly reconstructing the matter power spectrum from linear to non-linear scales. We demonstrate that cosmic shear surveys will be sensitive to the shape of the matter power spectrum on non-linear scales. We show that it should be possible to distinguish between different models of baryonic feedback and we investigate the impact of intrinsic alignments and observational systematics on forecasted constraints. In addition to providing important information on galaxy formation, power spectrum reconstruction should provide a definitive answer to the question of whether weak lensing measurements of |$S_8$| on linear scales are consistent with the Planck Lambda cold dark matter cosmology. In addition, power spectrum reconstruction may lead to new discoveries on the composition of the dark sector. [ABSTRACT FROM AUTHOR]

The Hubble constant (⁠|$H_0$|⁠), a crucial parameter in cosmology, quantifies the expansion rate of the universe so its precise measurement is important to understand the fundamental dynamics of our evolving universe. One of the major limitations of measuring |$H_0$| using time-delay cosmography is the presence of the mass-sheet degeneracy (MSD) in the lens mass modelling. We propose and quantitatively assess the use of galaxy–galaxy shear measurements to break the MSD in the strong lensing mass modelling. We use stacked galaxy–galaxy lensing profiles and corresponding covariance matrices from Huang et al. to constrain the MSD in lens mass modelling with a highly flexible mass profile. Our analyses show that if ideally all galaxy–galaxy lensing measurements from the Hyper Suprime-Cam survey can be used to constrain the MSD, we can achieve |$\sim 10~{{\ \rm per\ cent}}$| precision on the MSD constraint. We forecast that galaxy–galaxy lensing measurements from Legacy Survey of Space and Time (LSST)-like surveys can in general constrain the MSD with |$\sim 1\,\mathrm{ per\,cent}-3~{{\ \rm per\ cent}}$| precision. Furthermore, if we push weak lensing measurements to a lower angular scale of |$\sim 0.04\,\rm Mpc$|⁠ , a survey like LSST can provide |$\sim 1~{{\ \rm per\ cent}}$| precision on the MSD constraint, enabling a measurement of |$H_0$| at the 1 per cent level. We demonstrate that galaxy–galaxy weak lensing can robustly constrain the MSD independent of stellar kinematics of the deflector, with wide-field survey data alone. [ABSTRACT FROM AUTHOR]

In this paper, we compile a Fermi sample of the long gamma-ray bursts (GRB) observations from 15 years of GBM catalogue with identified redshift, in which the GOLD sample contains 123 long GRBs at |$z\le 5.6$| and the FULL sample contains 151 long GRBs with redshifts at |$z\le 8.2$|⁠. The Amati relation (the |$E_{\rm p,i}$| – |$E_{\rm iso}$| correlation) is calibrated at |$z\lt 1.4$| by a Gaussian Process from the latest observational Hubble data with the cosmic chronometers method so that GRBs at high-redshift |$z\ge 1.4$| can be used to constrain cosmological models via the Markov chain Monte Carlo (MCMC) method. From the cosmology-independent GRBs with the GOLD sample at |$z\ge 1.4$| and the Pantheon + sample of type Ia supernovae (SNe Ia) at |$0.01\lt z\le 2.3$|⁠ , we obtain |$\Omega _{\rm m} = 0.354\pm 0.018, H_0 = 73.05\pm 0.2\, \rm {km\,s^{-1}\,Mpc^{-1}}$| for the flat Lambda cold dark matter (⁠|$\Lambda$| CDM) model; |$w_0 = -1.22^{+0.18}_{-0.15}$| for the flat w CDM model; and |$w_{a} = -1.12^{+0.45}_{-0.83}$| for the flat Chevallier–Polarski–Linder model at the 1 |$\sigma$| confidence level. Our results with the GOLD and FULL sample are almost identical, which are more stringent than the previous results with GRBs. [ABSTRACT FROM AUTHOR]

The Hubble constant |$H_0$| tension has emerged as the most serious crisis in modern cosmology, potentially indicating that the |$\Lambda$| CDM model may not describe our Universe accurately. In this paper, we establish a new, cosmological-model-independent method to study the cosmic background dynamics. Using the latest Pantheon+ Type Ia supernova (SN Ia) sample and the model-independent SN Ia sample (P+1690), we derive values for the luminosity distance, the Hubble parameter, and the deceleration parameter at five different redshift points ranging from 0.12 to 0.52. Our analysis shows that results obtained from the Pantheon+ sample align with the predictions of the |$\Lambda$| CDM model within 2 |$\sigma$| confidence level (CL), while those obtained from the P+1690 sample exhibit deviations of about |$2\sim 3\sigma$| CL. Furthermore, we explore the equation of state (EoS) of dark energy and find that while the EoS values from the Pantheon+ sample remain consistent with |$-1$| within 2 |$\sigma$| CL, the P+1690 sample does not conform to this standard. These findings remain unchanged after the inclusion of the Hubble parameter measurements in our analysis. Our results indicate that the |$\Lambda$| CDM model remains compatible with the Pantheon+ SN Ia and the Hubble parameter measurements at 2 |$\sigma$| CL. [ABSTRACT FROM AUTHOR]

Patchy reionization generates kinematic Sunyaev–Zel'dovich (kSZ) anisotropies in the cosmic microwave background (CMB). Large-scale velocity perturbations along the line of sight modulate the small-scale kSZ power spectrum, leading to a trispectrum (or four-point function) in the CMB that depends on the physics of reionization. We investigate the challenges in detecting this trispectrum and use tools developed for CMB lensing, such as realization-dependent bias subtraction and cross-correlation based estimators, to counter uncertainties in the instrumental noise and assumed CMB power spectrum. We also find that both lensing and extragalactic foregrounds can impart larger trispectrum contributions than the reionization kSZ signal. We present a range of mitigation methods for both of these sources of contamination, validated on microwave-sky simulations. We use ACT DR6 and Planck data to calculate an upper limit on the reionization kSZ trispectrum from a measurement dominated by foregrounds. The upper limit is about 50 times the signal predicted from recent simulations. [ABSTRACT FROM AUTHOR]

We present constraints on the dark scattering model through cosmic shear measurements from the Kilo Degree Survey (KiDS-1000), using an accelerated pipeline with novel emulators produced with CosmoPower. Our main emulator, for the dark scattering non-linear matter power spectrum, is trained on predictions from the halo model reaction framework, previously validated against simulations. Additionally, we include the effects of baryonic feedback from HMCode2016 , whose contribution is also emulated. We analyse the complete set of statistics of KiDS-1000, namely band powers, COSEBIs, and correlation functions, for dark scattering in two distinct cases. In the first case, taking into account only KiDS cosmic shear data, we constrain the amplitude of the dark energy–dark matter interaction to be |$\vert A_{\rm ds} \vert \lesssim 20$| |$\rm b\,GeV^{-1}$| at 68  per cent C.L. Furthermore, we add information from the cosmic microwave background (CMB) from Planck, along with baryon acoustic oscillations (BAO) from 6dFGS, SDSS, and BOSS, approximating a combined weak lensing+CMB+BAO analysis. From this combination, we constrain |$A_{\rm ds} = 10.6^{+4.5}_{-7.3}$| |$\rm b\,GeV^{-1}$| at 68  per cent C.L. We confirm that with this estimated value of |$A_{\rm ds}$| the interacting model considered in this work offers a promising alternative to solve the |$S_8$| tension. [ABSTRACT FROM AUTHOR]

The detailed nature of dark energy remains a mystery, leaving the possibility that its effects might be explained by changes to the laws of gravity on large scales. The peculiar velocities of galaxies directly trace the strength of gravity on cosmic scales and provide a means to further constrain such models. We generate constraints on different scenarios of gravitational physics by measuring peculiar velocity (PV) and galaxy clustering two-point correlations, using redshifts and distances from the 6-degree Field Galaxy Survey and the Sloan Digital Sky Survey PV samples, and fitting them against models characteristic of different cosmologies. Our best-fitting results are all found to be in statistical agreement with general relativity, in which context we measure the low-redshift growth of structure to be |$f\sigma _8 = 0.329^{+0.081}_{-0.083}$|⁠ , consistent with the prediction of the standard Lambda cold dark matter model. We also fit the modified gravity scenarios of Dvali–Gabadadze–Porrati and a Hu–Sawicki model of |$f(R)$| gravity, finding the |$2\sigma$| limit of their characteristic parameters to be |$r_{\rm c}H_0/c\gt 6.987$| and |$-\log _{10}(|f_{R0}|)\gt 4.703$|⁠ , respectively. These constraints are comparable to other literature values, though it should be noted that they are significantly affected by the prior adopted for their characteristic parameters. When applied to much larger upcoming PV surveys such as DESI, this method will place rapidly improving constraints on modified gravity models of cosmic expansion and growth. [ABSTRACT FROM AUTHOR]

The ability of Big Bang Nucleosynthesis theory to accurately predict the primordial abundances of helium and deuterium, as well as the baryon content of the Universe, is considered one of the most significant achievements in modern physics. In the present study, we consider two highly motivated hybrid |$f(T)$| models and constrain them using the observations from the Big Bang Nucleosynthesis era. In addition, using late-time observations of Cosmic Chronometers and Gamma-Ray Bursts, the ranges of the model parameters are confined which are in good agreement with early time bounds. Subsequently, the common ranges obtained from the analysis for early and late time are summarized. Further, we verify the intermediating epochs by investigating the profiles of cosmographic parameters using the model parameter values from the common range. From this study, we find the considered teleparallel models are viable candidates to explain the primordial-intermediating-present epochs. [ABSTRACT FROM AUTHOR]

High precision mapping of H |$_{2}$| O megamaser emission from active galaxies has revealed more than a dozen Keplerian H |$_{2}$| O maser discs, which enable a |$\sim$| 4 per cent uncertainty estimate of the Hubble constant as well as providing accurate masses for the central black holes. These discs often have well-defined inner and outer boundaries of maser emission on sub-parsec scales. In order to better understand the physical conditions that determine the inner and outer radii of a maser disc, we examine the distributions of gas density and X-ray heating rate in a warped molecular disc described by a power-law surface density profile. For a suitable choice of the disc mass, we find that the outer radius |$R_{\rm out}$| of the maser disc predicted from our model can match the observed value, with |$R_{\rm out}$| mainly determined by the maximum heating rate or the minimum density for efficient maser action, depending on the combination of the Eddington ratio, black hole mass, and disc mass. Our analysis also indicates that the inner radius for maser action is comparable to the dust sublimation radius, suggesting that dust may play a role in determining the inner radius of a maser disc. Finally, our model predicts that H |$_{2}$| O gigamaser discs could exist at the centres of high-z quasars, with disc sizes of |$\gtrsim 10-30$| pc. [ABSTRACT FROM AUTHOR]

Deep learning (DL) has recently been proposed as a novel approach for 21cm foreground removal. Before applying DL to real observations, it is essential to assess its consistency with established methods, its performance across various simulation models, and its robustness against instrumental systematics. This study develops a commonly used U-Net and evaluates its performance for post-reionization foreground removal across three distinct sky simulation models based on pure Gaussian realizations, the Lagrangian perturbation theory, and the Planck sky model. Consistent outcomes across the models are achieved provided that training and testing data align with the same model. On average, the residual foreground in the U-Net reconstructed data is |$\sim 10~{{\ \rm per\ cent}}$| of the signal across angular scales at the considered redshift range. Comparable results are found with traditional approaches. However, blindly using a network trained on one model for data from another model yields inaccurate reconstructions, emphasizing the need for consistent training data. The study then introduces frequency-dependent Gaussian beams and bandpass fluctuations to the test data. The network struggles to denoise data affected by 'unexpected' systematics without prior information. However, after re-training consistently with systematics-contaminated data, the network effectively restores its reconstruction accuracy. Our results highlight the importance of incorporating prior knowledge during network training compared with established blind methods. Our work provides critical guidelines for using DL for 21cm foreground removal, tailored to specific data attributes. Notably, it is the first time that DL has been applied to the Planck sky model being most realistic foregrounds at present. [ABSTRACT FROM AUTHOR]

This study investigates the clustering and bias of Luminous Red Galaxies (LRG) in the BOSS-LOWZ, -CMASS, -COMB, and eBOSS samples, using two types of simulated lightcones: (i) high-fidelity lightcones from Uchuu N -body simulation, employing SHAM technique to assign LRG to (sub)haloes, and (ii) 16 000 covariance lightcones from GLAM-Uchuu N -body simulations, including LRG using HOD data from Uchuu. Our results indicate that Uchuu and glam lightcones closely replicate BOSS/eBOSS data, reproducing correlation function and power spectrum across scales from redshifts 0.2 to 1.0, from 2 to |$150 \,h^{-1}\,\mathrm{Mpc}$| in configuration space, from 0.005 to |$0.7\, h\,\mathrm{Mpc}^{-1}$| in Fourier space, and across different LRG stellar masses. Furthermore, comparing with existing MD-Patchy and EZmock BOSS/eBOSS lightcones based on approximate methods, our GLAM-Uchuu lightcones provide more precise clustering estimates. We identify significant deviations from observations within |$20 \,h^{-1}\,\mathrm{Mpc}$| scales in MD-Patchy and EZmock , with our covariance matrices indicating that these methods underestimate errors by between 10 per cent and 60 per cent. Lastly, we explore the impact of cosmology on galaxy clustering. Our findings suggest that, given the current level of uncertainties in BOSS/eBOSS data, distinguishing models with and without massive neutrino effects on large-scale structure (LSS) is challenging. This paper highlights the Uchuu and GLAM-Uchuu simulations' robustness in verifying the accuracy of Planck cosmological parameters, providing a strong foundation for enhancing lightcone construction in future LSS surveys. We also demonstrate that generating thousands of galaxy lightcones is feasible using N -body simulations with adequate mass and force resolution. [ABSTRACT FROM AUTHOR]

Exploring the marks left by galactic accretion in the Milky Way helps us understand how our Galaxy was formed. However, finding and studying accreted stars and the galaxies they came from has been challenging. This study uses a simulation from the Numerical Investigation of a Hundred Astronomical Objects project, which now includes a wider range of chemical compositions, to find better ways to spot these accreted stars. By comparing our findings with data from the GALAH spectroscopic survey, we confirm that the observationally established diagnostics of [Al/Fe] versus [Mg/Mn] also show a separation of in situ and accreted stars in the simulation, but stars from different accretion events tend to overlap in this plane even without observational uncertainties. Looking at the relationship between stellar age and linear or logarithmic abundances, such as [Fe/H], we can clearly separate different groups of these stars if the uncertainties in their chemical makeup are less than 0.15 dex and less than 20 per cent for their ages. This method shows promise for studying the history of the Milky Way and other galaxies. Our work highlights how important it is to have accurate measurements of stellar ages and chemical content. It also shows how simulations can help us understand the complex process of galaxies merging and suggest how these events might relate to the differences we see between our Galaxy's thin and thick disc stars. This study provides a way to compare theoretical models with real observations, opening new paths for research in both our own Galaxy and beyond. [ABSTRACT FROM AUTHOR]

Context. Weak gravitational lensing offers a powerful method to investigate the projected matter density distribution within galaxy clusters, granting crucial insights into the broader landscape of dark matter on cluster scales. Aims. In this study, we make use of the large photometric galaxy cluster data set derived from the publicly available Third Data Release of the Kilo-Degree Survey, along with the associated shear signal. Our primary objective is to model the peculiar sharp transition in the cluster profile slope, that is what is commonly referred to as the splashback radius. The data set under scrutiny includes 6962 galaxy clusters, selected by AMICO (an optimised detection algorithm of galaxy clusters) on the KiDS-DR3 data, in the redshift range of 0.1 ≤ z ≤ 0.6, all observed at a signal-to-noise ratio greater than 3.5. Methods. Employing a comprehensive Bayesian analysis, we model the stacked excess surface mass density distribution of the clusters. We adopt a model from recent results on numerical simulations that capture the dynamics of both orbiting and infalling materials, separated by the region where the density profile slope undergoes a pronounced deepening. Results. We find that the adopted profile successfully characterizes the cluster masses, consistent with previous works, and models the deepening of the slope of the density profiles measured with weak-lensing data up to the outskirts. Moreover, we measure the splashback radius of galaxy clusters and show that its value is close to the radius within which the enclosed overdensity is 200 times the mean matter density of the Universe, while theoretical models predict a larger value consistent with a low accretion rate. This points to a potential bias of optically selected clusters preferentially characterized by a high density at small scales compared to a pure mass-selected cluster sample. [ABSTRACT FROM AUTHOR]

Although it is well known that the bulk of dark matter (DM) has to be cold, the existence of an additional sub-dominant, hot species remains a valid possibility. In this paper we investigate the potential of the cosmic shear power spectrum to constrain such a mixed (hot plus cold) DM scenario with two additional free parameters, the hot-to-total DM fraction (fhdm) and the thermal mass of the hot component (mhdm). Running a Bayesian inference analysis for both the Kilo-Degree Survey cosmic shear data (KiDS-1000) as well as the cosmic microwave background (CMB) temperature and polarisation data from Planck, we derive new constraints for the mixed DM scenario. We find a 95% confidence limit of fhdm < 0.08 for a very hot species of mhdm ≤ 20 eV. This constraint is weakened to fhdm < 0.25 for mhdm ≤ 80 eV. Scenarios with masses above mhdm ∼ 200 eV remain unconstrained by the data. Next to providing limits, we investigate the potential of mixed DM to address the clustering (or S8) tension between lensing and the CMB. We find a reduction of the 2D (Ωm − S8) tension from 2.9σ to 1.6σ when going from a pure cold DM to a mixed DM scenario. When computing the 1D Gaussian tension on S8 the improvement is milder, from 2.4σ to 2.0σ. [ABSTRACT FROM AUTHOR]

The physics of the accelerating Universe (PAU) camera is an optical narrow band and broad band imaging instrument mounted at the prime focus of the William Herschel Telescope. We describe the image calibration procedure of the PAU survey data. We rely on an external photometric catalogue to calibrate our narrow band data using stars that have been observed by both data sets. We fit stellar templates to the stellar broad-band photometry of the Sloan Digital Sky Survey and synthesize narrow band photometry that we compare to the PAUS narrow band data to determine their calibration. Consequently, the PAUS data are in the AB system as inherited from its reference calibrator. We do several tests to check the performance of the calibration. We find it self-consistent when comparing repeated observations of the same objects, with a good overall accuracy to the AB system which we estimate to be at the 2 per cent precision level and no significant trends as a function of narrow band filter or wavelength. Repeated observations allow us to build a spatial map of the illumination pattern of the system. We also check the wavelength dependence of the calibration comparing to stellar spectra. We find that using only blue stars reduces the effects of variations in the stellar template fitting to broad-band colours, improving the overall precision of the calibration to around 1 per cent and its wavelength uniformity. The photometric redshift performance obtained with the PAUS data attests to the validity of our calibration to reach the PAUS science goals. [ABSTRACT FROM AUTHOR]

Galaxy clustering measurements are a key probe of the matter density field in the Universe. With the era of precision cosmology upon us, surveys rely on precise measurements of the clustering signal for meaningful cosmological analysis. However, the presence of systematic contaminants can bias the observed galaxy number density, and thereby bias the galaxy two-point statistics. As the statistical uncertainties get smaller, correcting for these systematic contaminants becomes increasingly important for unbiased cosmological analysis. We present and validate a new method for understanding and mitigating both additive and multiplicative systematics in galaxy clustering measurements (two-point function) by joint inference of contaminants in the galaxy overdensity field (one-point function) using a maximum-likelihood estimator (MLE). We test this methodology with Kilo-Degree Survey-like mock galaxy catalogues and synthetic systematic template maps. We estimate the cosmological impact of such mitigation by quantifying uncertainties and possible biases in the inferred relationship between the observed and the true galaxy clustering signal. Our method robustly corrects the clustering signal to the sub-per cent level and reduces numerous additive and multiplicative systematics from |$1.5 \sigma$| to less than |$0.1\sigma$| for the scenarios we tested. In addition, we provide an empirical approach to identifying the functional form (additive, multiplicative, or other) by which specific systematics contaminate the galaxy number density. Even though this approach is tested and geared towards systematics contaminating the galaxy number density, the methods can be extended to systematics mitigation for other two-point correlation measurements. [ABSTRACT FROM AUTHOR]

We examine the sky distribution of radio galaxies in the NRAO VLA Sky Survey (NVSS) and the Rapid ASKAP Continuum Survey (RACS). Analyses of these samples have reported tension between their inferred dipoles and the kinematic dipole of the cosmic microwave background (CMB). This represents a challenge to the traditional assumption that the Universe is homogeneous and isotropic on large scales: the cosmological principle. We find that NVSS and RACS contain local radio sources that give a non-negligible contribution to the overall dipole signal. These need to be adequately accounted for since the aim is to probe the composition of the Universe at large scales. By appropriately considering these sources, the inferred dipole amplitude in either sample is reduced. None the less, we find support for a dipole aligning with that of the CMB but larger in amplitude, especially in the joint analysis. However, the 'clustering dipole' – the contribution of local sources to the net inferred dipole – appears to align with the direction of the CMB dipole, and its magnitude increases as deeper nearby sources are considered up to a comoving distance of ≈130 Mpc (h  = 0.7). The significance of this observation in the context of the cosmological principle is unclear and prompts further inquiry. [ABSTRACT FROM AUTHOR]

The advent of JWST now allows entire star cluster populations to be imaged in galaxies at cosmologically significant redshifts, bringing with it the need to apply K -corrections to their magnitudes and colour indices. Since the stellar populations within star clusters can be well approximated by a single age and metallicity, their spectral energy distributions are very different from those of galaxies or supernovae, and their K -corrections behave differently. We derive the photometric K -corrections versus redshift for model star clusters that cover a wide range of ages and metallicities, illustrating the results particularly for the broad-band filters on the Hubble Space Telescope /Advanced Camera for Surveys and the JWST /Near-Infrared Camera that are most commonly being used for imaging of populations of star clusters in distant galaxies. In an appendix, we introduce a webtool called rescuer (REdshifted Star ClUstERs) that can generate K -values and their uncertainties for any user-defined combination of cluster properties. [ABSTRACT FROM AUTHOR]

The spectroscopic survey of the China's Space Survey Telescope (CSST) is expected to obtain a huge number of slitless spectra, including more than one hundred million galaxy spectra and millions of active galactic nuclei (AGNs) spectra. By making use of these spectra, we can measure the Baryon Acoustic Oscillation (BAO) signals over large redshift ranges with excellent precisions. In this work, we predict the CSST measurements of the post-reconstruction galaxy power spectra at |$0\lt z\lt 1.2$| and pre-reconstruction AGN power spectra at |$0\lt z\lt 4$|⁠ , and derive the BAO signals at different redshift bins by constraining the BAO scaling parameters using the Markov Chain Monte Carlo method. Our result shows that the CSST spectroscopic survey can provide accurate BAO measurements with precisions higher than 1 and 3 per cent for the galaxy and AGN surveys, respectively. By comparing with current measurements in the same range at low redshifts, this can improve the precisions by a factor of |$2\sim 3$|⁠ , and similar precisions can be obtained in the pessimistic case. We also investigate the constraints on the cosmological parameters using the measured BAO data by the CSST , and obtain stringent constraint results for the energy density of dark matter, Hubble constant, and equation of state of dark energy. [ABSTRACT FROM AUTHOR]

Fitting model spectral energy distributions (SEDs) to galaxy photometric data is a widely used method to recover galaxy parameters from galaxy surveys. However, the parameter space used to describe galaxies is wide and interdependent, and distinctions between real and spurious correlations that are found between these parameters can be difficult to discern. In this work, we use the SED fitting code bagpipes (Bayesian Analysis of Galaxies for Physical Inference and Parameter EStimation) to investigate degeneracies between galaxy parameters and the effect of the choice of different sets of photometric bands. In particular, we focus on optical to infrared wavelength coverage, and on two parameters describing the galaxies' dust attenuation law: AV and δ, which characterize dust column density and the slope of a flexible dust attenuation law, respectively. We demonstrate that (1) a degeneracy between the residual (the difference between truth and recovered values) AV and star formation rate exists, but this is lifted when Wide-Field Infrared Survey Explorer bands are included, and (2) bagpipes is able to accurately recover the input AV and δ distributions and relations (differences in slope of less than 1.7σ for a flat relation and less than 1.2σ for an observationally motivated relation) and is not introducing spurious correlations between these parameters. Our findings suggest that the information needed to constrain AV and δ well enough individually exists in the data, especially when infrared is added. This indicates that recent works finding a correlation between AV and δ are not being misled by fitting degeneracies from their SED fitting code. [ABSTRACT FROM AUTHOR]

Gravitational waves from neutron star mergers have long been considered a promising way to measure the Hubble constant, H 0, which describes the local expansion rate of the Universe. While black hole mergers are more abundantly observed, their expected lack of electromagnetic emission and poor gravitational-wave localization make them less well suited for measuring H 0. Black hole mergers within the discs of Active Galactic Nuclei (AGN) could be an exception. Accretion from the AGN disc may produce an electromagnetic signal, pointing observers to the host galaxy. Alternatively, the low number density of AGNs could help identify the host galaxy of |$1{\!-\!}5~{{\ \rm per\ cent}}$| of mergers. Here we show that black hole mergers in AGN discs may be a sensitive way to determine H 0 with gravitational waves. If 1 per cent (10 per cent) of LIGO's observations occur in AGN discs with identified host galaxies, we could measure H 0 with 12 per cent (4 per cent) uncertainty in five years, possibly comparable to the sensitivity of neutron star mergers and set to considerably improve current gravitational wave measurements. [ABSTRACT FROM AUTHOR]

Clusters of galaxies trace the most non-linear peaks in the cosmic density field. The weak gravitational lensing of background galaxies by clusters can allow us to infer their masses. However, galaxies associated with the local environment of the cluster can also be intrinsically aligned due to the local tidal gradient, contaminating any cosmology derived from the lensing signal. We measure this intrinsic alignment in Dark Energy Survey (DES) Year 1 REDMAPPER clusters. We find evidence of a non-zero mean radial alignment of galaxies within clusters between redshifts 0.1–0.7. We find a significant systematic in the measured ellipticities of cluster satellite galaxies that we attribute to the central galaxy flux and other intracluster light. We attempt to correct this signal, and fit a simple model for intrinsic alignment amplitude (AIA) to the measurement, finding AIA = 0.15 ± 0.04, when excluding data near the edge of the cluster. We find a significantly stronger alignment of the central galaxy with the cluster dark matter halo at low redshift and with higher richness and central galaxy absolute magnitude (proxies for cluster mass). This is an important demonstration of the ability of large photometric data sets like DES to provide direct constraints on the intrinsic alignment of galaxies within clusters. These measurements can inform improvements to small-scale modelling and simulation of the intrinsic alignment of galaxies to help improve the separation of the intrinsic alignment signal in weak lensing studies.

Combining different observational probes, such as galaxy clustering and weak lensing, is a promising technique for unveiling the physics of the Universe with upcoming dark energy experiments. The galaxy redshift sample from the Dark Energy Spectroscopic Instrument (DESI) will have a significant overlap with major ongoing imaging surveys specifically designed for weak lensing measurements: The Kilo-Degree Survey (KiDS), the Dark Energy Survey (DES), and the Hyper Suprime-Cam (HSC) survey. In this work, we analyse simulated redshift and lensing catalogues to establish a new strategy for combining high-quality cosmological imaging and spectroscopic data, in view of the first-year data assembly analysis of DESI. In a test case fitting for a reduced parameter set, we employ an optimal data compression scheme able to identify those aspects of the data that are most sensitive to cosmological information and amplify them with respect to other aspects of the data. We find this optimal compression approach is able to preserve all the information related to the growth of structures.

We describe the target selection and characteristics of the DESI Peculiar Velocity Survey, the largest survey of peculiar velocities (PVs) using both the fundamental plane (FP) and the Tully-Fisher (TF) relationship planned to date. We detail how we identify suitable early-type galaxies (ETGs) for the FP and suitable late-type galaxies (LTGs) for the TF relation using the photometric data provided by the DESI Legacy Imaging Survey DR9. Subsequently, we provide targets for 373 533 ETGs and 118 637 LTGs within the Dark Energy Spectroscopic Instrument (DESI) 5-yr footprint. We validate these photometric selections using existing morphological classifications. Furthermore, we demonstrate using survey validation data that DESI is able to measure the spectroscopic properties to sufficient precision to obtain PVs for our targets. Based on realistic DESI fibre assignment simulations and spectroscopic success rates, we predict the final DESI PV Survey will obtain ∼133 000 FP-based and ∼53 000 TF-based PV measurements over an area of 14 000 deg2. We forecast the ability of using these data to measure the clustering of galaxy positions and PVs from the combined DESI PV and Bright Galaxy Surveys (BGS), which allows for cancellation of cosmic variance at low redshifts. With these forecasts, we anticipate a 4 per cent statistical measurement on the growth rate of structure at z < 0.15. This is over two times better than achievable with redshifts from the BGS alone. The combined DESI PV and BGS will enable the most precise tests to date of the time and scale dependence of large-scale structure growth at z < 0.15.

The shear measurement from the Dark Energy Camera Legacy Survey (DECaLS) provides an excellent opportunity for galaxy-galaxy lensing study with the Dark Energy Spectroscopic Instrument (DESI) galaxies, given the large (∼9000 deg2) sky overlap. We explore this potential by combining the DESI 1 per cent survey and DECaLS Data Release 8 (DR8). With ∼106 deg2 sky overlap, we achieve significant detection of galaxy-galaxy lensing for Bright Galaxy Survey (BGS) and luminous red galaxy (LRG) as lenses. Scaled to the full BGS sample, we expect the statistical errors to improve from to a promising level of at. This brings stronger requirements for future systematics control. To fully realize such potential, we need to control the residual multiplicative shear bias |m| < 0.006 and the bias in the mean redshift |Δz| < 0.008, requiring the introduced bias in the measurement is

We present, for the first time, an observational test of the consistency relation for the large-scale structure (LSS) of the Universe through a joint analysis of the anisotropic two- and three-point correlation functions (2PCF and 3PCF) of galaxies. We parameterize the breakdown of the LSS consistency relation in the squeezed limit by Es, which represents the ratio of the coefficients of the shift terms in the second-order density and velocity fluctuations. Es ≠ 1 is a sufficient condition under which the LSS consistency relation is violated. A novel aspect of this work is that we constrain Es by obtaining information about the non-linear velocity field from the quadrupole component of the 3PCF without taking the squeezed limit. Using the galaxy catalogues in the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12, we obtain, indicating that there is no violation of the LSS consistency relation in our analysis within the statistical errors. Our parameterization is general enough that our constraint can be applied to a wide range of theories, such as multicomponent fluids, modified gravity theories, and their associated galaxy bias effects. Our analysis opens a new observational window to test the fundamental physics using the anisotropic higher-order correlation functions of galaxy clustering.

JWST has recently sparked a new era of Lyα spectroscopy, delivering the first measurements of the Lyα escape fraction and velocity profile in typical galaxies at z ≃ 6−10. These observations offer new prospects for insight into the earliest stages of reionization. But to realize this potential, we need robust models of Lyα properties in galaxies at z ≃ 5−6 when the IGM is mostly ionized. Here, we use new JWST observations from the JADES and FRESCO surveys combined with VLT/MUSE and Keck/DEIMOS data to characterize statistical distributions of Lyα velocity offsets, escape fractions, and EWs in z ≃ 5−6 galaxies. We find that galaxies with large Lyα escape fractions (>0.2) are common at z ≃ 5−6, comprising 30 per cent of Lyman break selected samples. Comparing to literature studies, our census suggests that Lyα becomes more prevalent in the galaxy population towards higher redshift from z ∼ 3 to z ∼ 6, although we find that this evolution slows considerably between z ∼ 5 and z ∼ 6, consistent with modest attenuation from residual H i in the mostly ionized IGM at z ≃ 5−6. We find significant evolution in Lyα velocity profiles between z ≃ 2−3 and z ≃ 5−6, likely reflecting the influence of resonant scattering from residual intergalactic H i on the escape of Lyα emission near line centre. This effect will make it challenging to use Lyα peak offsets as a probe of Lyman continuum leakage at z ≃ 5−6. We use our z ≃ 5−6 Lyα distributions to make predictions for typical Lyα properties at z ≳ 8 and discuss implications of a recently discovered Lyα emitter at z ≃ 8.5 with a small peak velocity offset (156 km s−1). [ABSTRACT FROM AUTHOR]

Strong gravitational lensing is a powerful probe of the distribution of matter on sub-kpc scales. It can be used to test the existence of completely dark sub-haloes surrounding galaxies, as predicted by the standard cold dark matter model, or to test alternative dark matter models. The constraining power of the method depends strongly on photometric and astrometric precision and accuracy. We simulate and quantify the capabilities of upcoming adaptive optics systems and advanced instruments on ground-based telescopes, focusing as an illustration on the Keck Telescope (OSIRIS + KAPA, LIGER + KAPA) and the Thirty Meter Telescope (TMT; IRIS + NFIRAOS). We show that these new systems will achieve dramatic improvements over current ones in both photometric and astrometric precision. Narrow line flux ratio errors below 2 per cent, and submilliarcsecond astrometric precision will be attainable for typical quadruply imaged quasars. With TMT, the exposure times required will be of order a few minutes per system, enabling the follow-up of 100–1000 systems expected to be discovered by the Rubin, Euclid, and Roman Telescopes. [ABSTRACT FROM AUTHOR]

There have been many efforts in the last three decades to embed the empirical Modified Newtonian Dynamics (MOND) programme into a robust theoretical framework. While many such theories can explain the profile of galactic rotation curves, they usually cannot explain the evolution of the primordial fluctuations and the formation of large-scale structures in the Universe. The Aether Scalar Tensor theory seems to have overcome this difficulty, thereby providing the first compelling example of an extension of general relativity able to successfully challenge the particle dark matter hypothesis. Here, we study the phenomenology of this theory in the quasistatic weak-field regime and specifically for the idealized case of spherical isolated sources. We find the existence of three distinct gravitational regimes, that is, Newtonian, MOND, and a third regime characterized by the presence of oscillations in the gravitational potential which do not exist in the traditional MOND paradigm. We identify the transition scales between these three regimes and discuss their dependence on the boundary conditions and other parameters in the theory. Aided by analytical and numerical solutions, we explore the dependence of these solutions on the theory parameters. Our results could help in searching for interesting observable phenomena at low redshift pertaining to galaxy dynamics as well as lensing observations, however, this may warrant proper N -body simulations that go beyond the idealized case of spherical isolated sources. [ABSTRACT FROM AUTHOR]

We use the spherical collapse model to demonstrate that the observable average density of virialized clusters depends on the properties of dark energy along with the properties of gravity on cluster scales and can therefore be used as a probe of these properties. As an application of this approach, we derive the predicted virialized densities and radii of cluster mass structures for a wide range of values of the cosmological constant (including negative values) as a function of the turnaround redshift. For the value of ΩΛ,0 = −0.7 (with Ω m ,0 = 0.3), we find an amplification of the density of virialized clusters which can be as large as 80 per cent compared to Planck18/lambda Cold Dark Matter (ΛCDM) for a turnaround redshift z max ≳ 2. Such an amplification may lead to more efficient early galaxy formation in this class of models, in accordance with the recent findings of JWST , which may be partially pertinent to the Λ sign switching models (ΛsCDM), which have been suggested as potential solutions to the observed Hubble and S 8 discrepancies. [ABSTRACT FROM AUTHOR]

Cosmological parameters can be measured by comparing peculiar velocities with those predicted from a galaxy density field. Previous work has tested the accuracy of this approach with N -body simulations, but generally on idealized mock galaxy surveys. However, systematic biases may arise solely due to survey selection effects such as flux-limited samples, edge-effects, and complications due to the obscuration of the Galactic plane. In this work, we explore the impact of each of these effects individually as well as collectively using the semi-analytic models from numerical simulations to generate mock catalogues that mimic the 2M++ density field. We find the reconstruction and analysis methods used for our 2M++ mocks produce a value of f σ8 that is biased high by a factor 1.04 ± 0.01 compared to the true value. Moreover, a cosmic volume matching that of 2M++ has a cosmic variance uncertainty in f σ8 of |$\sim 5~{{\ \rm per\ cent}}$|⁠. The systematic bias is a function of distance: it is unbiased close to the origin but is biased slightly high for distances in the range 100–180  h −1 Mpc. Correcting for this small bias, we find that recent peculiar velocity samples yield |$f\sigma _8^{\textrm {lin}} = 0.362\pm 0.023$|⁠ , a value that is in tension with the extrapolations from cosmic microwave background measurements. The predicted peculiar velocities from 2M++ have an error of 170 km s−1 that slowly increases with distance, exceeding 200 km s−1 only at distances of 180–200  h −1Mpc. Finally, the residual bulk flow speeds found in previous work are shown to be not in conflict with those expected in the Λ cold dark matter model. [ABSTRACT FROM AUTHOR]

The Merian survey is mapping ∼ 850 deg2 of the Hyper Suprime-Cam Strategic Survey Program (HSC-SSP) wide layer with two medium-band filters on the 4-m Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory, with the goal of carrying the first high signal-to-noise (S/N) measurements of weak gravitational lensing around dwarf galaxies. This paper presents the design of the Merian filter set: N708 (λ c  = 7080 Å, Δλ = 275 Å) and N540 (λ c  = 5400 Å, Δλ = 210 Å). The central wavelengths and filter widths of N708 and N540 were designed to detect the |$\rm H\alpha$| and |$\rm [OIII]$| emission lines of galaxies in the mass range |$8\lt \rm \log M_*/M_\odot \lt 9$| by comparing Merian fluxes with HSC broad-band fluxes. Our filter design takes into account the weak lensing S/N and photometric redshift performance. Our simulations predict that Merian will yield a sample of ∼ 85 000 star-forming dwarf galaxies with a photometric redshift accuracy of σΔ z /(1 + z) ∼ 0.01 and an outlier fraction of |$\eta =2.8~{{\ \rm per\ cent}}$| over the redshift range 0.058 < z < 0.10. With 60 full nights on the Blanco/Dark Energy Camera (DECam), the Merian survey is predicted to measure the average weak lensing profile around dwarf galaxies with lensing S/N ∼32 within r < 0.5 Mpc and lensing S/N ∼90 within r < 1.0 Mpc. This unprecedented sample of star-forming dwarf galaxies will allow for studies of the interplay between dark matter and stellar feedback and their roles in the evolution of dwarf galaxies. [ABSTRACT FROM AUTHOR]

We propose that observations of supermassive galaxies contain cosmological statistical constraining power similar to conventional cluster cosmology, and we provide promising indications that the associated systematic errors are comparably easier to control. We consider a fiducial spectroscopic and stellar mass complete sample of galaxies drawn from the Dark Energy Spectroscopic Instrument (DESI) and forecast how constraints on Ωm–σ8 from this sample will compare with those from number counts of clusters based on richness λ. At fixed number density, we find that massive galaxies offer similar constraints to galaxy clusters. However, a mass-complete galaxy sample from DESI has the potential to probe lower halo masses than standard optical cluster samples (which are typically limited to λ ≳ 20 and M halo ≳ 1013.5 M⊙  h −1); additionally, it is straightforward to cleanly measure projected galaxy clustering w p for such a DESI sample, which we show can substantially improve the constraining power on Ωm. We also compare the constraining power of M *-limited samples to those from larger but mass-incomplete samples [e.g. the DESI Bright Galaxy Survey (BGS) sample]; relative to a lower number density M *-limited samples, we find that a BGS-like sample improves statistical constraints by 60 per cent for Ωm and 40 per cent for σ8, but this uses small-scale information that will be harder to model for BGS. Our initial assessment of the systematics associated with supermassive galaxy cosmology yields promising results. The proposed samples have a ∼10 per cent satellite fraction, but we show that cosmological constraints may be robust to the impact of satellites. These findings motivate future work to realize the potential of supermassive galaxies to probe lower halo masses than richness-based clusters and to potentially avoid persistent systematics associated with optical cluster finding. [ABSTRACT FROM AUTHOR]

Gravitational waves (GWs) provide a new avenue to test Einstein's General Relativity (GR) using the ongoing and upcoming GW detectors by measuring the redshift evolution of the effective Planck mass proposed by several modified theories of gravity. We propose a model-independent, data-driven approach to measure any deviation from GR in the GW propagation effect by combining multimessenger observations of GW sources accompanied by EM counterparts, commonly known as bright sirens [Binary Neutron Star (BNS) and Neutron Star Black Hole systems (NSBH)]. We show that by combining the GW luminosity distance measurements from bright sirens with the Baryon Acoustic Oscillation (BAO) measurements derived from galaxy clustering, and the sound horizon measurements from the Cosmic Microwave Background (CMB), we can make a data-driven reconstruction of deviation of the variation of the effective Planck mass (jointly with the Hubble constant) as a function of cosmic redshift. Using this technique, we achieve a precise measurement of GR with redshift (z) with a precision of approximately 7.9 per cent for BNSs at redshift z = 0.075 and 10 per cent for NSBHs at redshift z = 0.225 with 5 yr of observation from LIGO-Virgo-KAGRA network of detectors. Employing Cosmic Explorer and Einstein Telescope for just 1 yr yields the best precision of about 1.62 per cent for BNSs and 2 per cent for NSBHs at redshift z = 0.5 on the evolution of the frictional term, and a similar precision up to z = 1. This measurement can discover potential deviation from any kind of model that impacts GW propagation with ongoing and upcoming observations. [ABSTRACT FROM AUTHOR]

This work explores the relationships between galaxy sizes and related observable galaxy properties in a large volume cosmological hydrodynamical simulation. The objectives of this work are to develop a better understanding of both the correlations between galaxy properties and the influence of environment on galaxy physics in order to build an improved model for the galaxy sizes, building off of the fundamental plane. With an accurate intrinsic galaxy size predictor, the residuals in the observed galaxy sizes can potentially be used for multiple cosmological applications, including making measurements of galaxy velocities in spectroscopic samples, estimating the rate of cosmic expansion, and constraining the uncertainties in the photometric redshifts of galaxies. Using projection pursuit regression, the model accurately predicts intrinsic galaxy sizes and have residuals which have limited correlation with galaxy properties. The model decreases the spatial correlation of galaxy size residuals by a factor of ∼5 at small scales compared to the baseline correlation when the mean size is used as a predictor. [ABSTRACT FROM AUTHOR]

In this paper, we use quasars calibrated from type Ia supernova (SN Ia) to constrain cosmological models. We consider three different X-ray luminosity (L X)–ultraviolet luminosity (L UV) relations of quasars, i.e. the standard L X– L UV relation and two redshift–evolutionary relations (Type I and Type II), respectively, constructed from copula and considering a redshift correction to the luminosity of quasars. Only in the case of the Type I relation, quasars can always provide effective constraints on the ΛCDM (cosmological constant Λ plus cold dark matter) model. Furthermore, we show that, when the observational Hubble data (OHD) are added, the constraints on the absolute magnitude M of SN Ia and the Hubble constant H 0 can be obtained. In the ΛCDM model, the OHD measurements plus quasars with the Type I relation yields M  =  |$-19.321^{+0.085}_{-0.076}$|⁠ , which is in good agreement with the measurement from SH0ES (M  = −19.253 ± 0.027), and H 0 =  |$70.80\pm 3.6~\mathrm{km~s^{-1}\, Mpc^{-1}}$|⁠ , falling between the measurements from SH0ES and the Planck cosmic microwave background radiation data. [ABSTRACT FROM AUTHOR]