Redshift Bins Research Articles

Faster cosmological analysis with power spectrum without simulations

ABSTRACT Future surveys could obtain tighter constraints on the cosmological parameters with the galaxy power spectrum than with the cosmic microwave background. However, the inclusion of multiple overlapping tracers, redshift bins, and more non-linear scales means that generating the necessary ensemble of simulations for model-fitting presents a computational burden. In this work, we combine full-shape fitting of galaxy power spectra, analytical covariance matrix estimates, the massively optimized parameter estimation and data compression (MOPED) method, and the Taylor expansion interpolation of the power spectrum for the first time to constrain the cosmological parameters directly from a state-of-the-art set of galaxy clustering measurements. We find it takes less than a day to compute the analytical covariance while it takes several months to calculate the simulated ones. Combining MOPED with the Taylor expansion interpolation of the power spectrum, we can constrain the cosmological parameters in just a few hours instead of a few days. We also find that even without a priori knowledge of the best-fitting cosmological or galaxy bias parameters, the analytical covariance matrix with the MOPED compression still gives consistent cosmological constraints to within 0.1σ after two iterations. Therefore, the pipeline we have developed here can significantly speed up the analysis for future surveys.

A JWST investigation into the bar fraction at redshifts 1 ≤ z ≤ 3

ABSTRACT The presence of a stellar bar in a disc galaxy indicates that the galaxy hosts in its main part a dynamically settled disc and that bar-driven processes are taking place in shaping its evolution. Studying the cosmic evolution of the bar fraction in disc galaxies is therefore essential to understand galaxy evolution in general. Previous studies have found, using the Hubble Space Telescope (HST), that the bar fraction significantly declines from the local Universe to redshifts near one. Using the first four pointings from the JWST Cosmic Evolution Early Release Science Survey and the initial public observations for the Public Release Imaging for Extragalactic Research, we extend the studies of the bar fraction in disc galaxies to redshifts 1 ≤ $z$ ≤ 3, that is, for the first time beyond redshift two. We only use galaxies that are also present in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey on the Extended Groth Strip and Ultra Deep Survey HST observations. An optimized sample of 368 close-to-face-on galaxies is visually classified to find the fraction of bars in disc galaxies in two redshift bins: 1 ≤ $z$ ≤ 2 and 2 < $z$ ≤ 3. The bar fraction decreases from $\approx 17.8^{+ 5.1}_{- 4.8}$ per cent to $\approx 13.8^{+ 6.5}_{- 5.8}$ per cent (from the lower to the higher redshift bin), but is about twice the bar fraction found using bluer HST filters. Our results show that bar-driven evolution might commence at early cosmic times and that dynamically settled discs are already present at a lookback time of ∼11 Gyr.

Impact of property covariance on cluster weak lensing scaling relations

ABSTRACT We present an investigation into a hitherto unexplored systematic that affects the accuracy of galaxy cluster mass estimates with weak gravitational lensing. Specifically, we study the covariance between the weak lensing signal, ΔΣ, and the ‘true’ cluster galaxy number count, Ngal, as measured within a spherical volume that is void of projection effects. By quantifying the impact of this covariance on mass calibration, this work reveals a significant source of systematic uncertainty. Using the MDPL2 simulation with galaxies traced by the SAGE semi-analytic model, we measure the intrinsic property covariance between these observables within the three-dimensional vicinity of the cluster, spanning a range of dynamical mass and redshift values relevant for optical cluster surveys. Our results reveal a negative covariance at small radial scales (R ≲ R200c) and a null covariance at large scales (R ≳ R200c) across most mass and redshift bins. We also find that this covariance results in a $2{\!-\!}3~{{\ \rm per\ cent}}$ bias in the halo mass estimates in most bins. Furthermore, by modelling Ngal and ΔΣ as multi-(log)-linear equations of secondary halo properties, we provide a quantitative explanation for the physical origin of the negative covariance at small scales. Specifically, we demonstrate that the Ngal–ΔΣ covariance can be explained by the secondary properties of haloes that probe their formation history. We attribute the difference between our results and the positive bias seen in other works with (mock)-cluster finders to projection effects. These findings highlight the importance of accounting for the covariance between observables in cluster mass estimation, which is crucial for obtaining accurate constraints on cosmological parameters.

The DESI one-per cent survey: exploring the halo occupation distribution of luminous red galaxies and quasi-stellar objects with AbacusSummit

ABSTRACT We present the first comprehensive halo occupation distribution (HOD) analysis of the Dark Energy Spectroscopic Instrument (DESI) One-Percent Survey luminous red galaxy (LRG) and Quasi Stellar Object (QSO) samples. We constrain the HOD of each sample and test possible HOD extensions by fitting the redshift-space galaxy 2-point correlation functions in 0.15 < r < 32 h−1 Mpc in a set of fiducial redshift bins. We use AbacusSummit cubic boxes at Planck 2018 cosmology as model templates and forward model galaxy clustering with the AbacusHOD package. We achieve good fits with a standard HOD model with velocity bias, and we find no evidence for galaxy assembly bias or satellite profile modulation at the current level of statistical uncertainty. For LRGs in 0.4 < z < 0.6, we infer a satellite fraction of $f_\mathrm{sat} = 11\pm 1~{y{\ \mathrm{per\,cent}}}$, a mean halo mass of $\log _{10}\overline{M}_h/M_\odot =13.40^{+0.02}_{-0.02}$, and a linear bias of $b_\mathrm{lin} = 1.93_{-0.04}^{+0.06}$. For LRGs in 0.6 < z < 0.8, we find $f_\mathrm{sat}=14\pm 1~{{\ \mathrm{per\,cent}}}$, $\log _{10}\overline{M}_h/M_\odot =13.24^{+0.02}_{-0.02}$, and $b_\mathrm{lin}=2.08_{-0.03}^{+0.03}$. For QSOs, we infer $f_\mathrm{sat}=3^{+8}_{-2}\mathrm{per\,cent}$, $\log _{10}\overline{M}_h/M_\odot = 12.65^{+0.09}_{-0.04}$, and $b_\mathrm{lin} = 2.63_{-0.26}^{+0.37}$ in redshift range 0.8 < z < 2.1. Using these fits, we generate a large suite of high fidelity galaxy mocks, forming the basis of systematic tests for DESI Y1 cosmological analyses. We also study the redshift-evolution of the DESI LRG sample from z = 0.4 up to z = 1.1, revealling significant and interesting trends in mean halo mass, linear bias, and satellite fraction.

Covariance matrices for the Lyman-α forest using the lognormal approximation

We investigate the nature of correlations in the small-scale flux statistics of the Lyman-α (Lyα) forest across redshift bins. Understanding and characterising these correlations is important for unbiased cosmological and astrophysical parameter inference using the Lyα forest. We focus on the 1-dimensional flux power spectrum (FPS) and mean flux (F̅) simulated using the semi-numerical lognormal model we developed in earlier work. The lognormal model can capture the effects of long wavelength modes with relative ease as compared to full smoothed particle hydrodynamical (SPH) simulations that are limited by box volume. For a single redshift bin of size Δz ≃ 0.1, we show that the lognormal model predicts positive cross-correlations between k-bins in the FPS, and a negative correlation for F̅ × FPS, in qualitative agreement with SPH simulations and theoretical expectations. For measurements across two neighbouring redshift bins of width Δ z each (using long flux skewers of length 2Δ z that are 'split' in half), the lognormal model predicts an anti-correlation for FPS × FPS and a positive correlation for F̅ × FPS, caused by modes with the longest wavelengths. This is in contrast to SPH simulations which predict a negligible magnitude for cross-redshift correlations derived from such `split' skewers, and we discuss possible reasons for this difference. Finally, we perform a preliminary test of the impact of neglecting long wavelength modes on parameter inference, finding that whereas the correlation structure of neighbouring redshift bins has relatively little impact, the absence of long wavelength modes in the model can lead to ≳ 2 - σ biases in the inference of astrophysical parameters. Our results motivate a more careful treatment of long wavelength modes in analyses that rely on the small-scale Lyα forest for parameter inference.

EPOCHS. II. The Ultraviolet Luminosity Function from 7.5 < z < 13.5 Using 180 arcmin2 of Deep, Blank Fields from the PEARLS Survey and Public JWST Data

We present an analysis of the ultraviolet luminosity function (UV LF) and star formation rate density of distant galaxies (7.5 < z < 13.5) in the “blank” fields of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) survey combined with Early Release Science data from the CEERS, GLASS, and NGDEEP surveys/fields and the first data release of JADES. We use strict quality cuts on EAZY photometric redshifts to obtain a reliable selection and characterization of high-redshift (z > 6.5) galaxies from a consistently processed set of deep, near-infrared imaging. Within an area of 180 arcmin2, we identify 1046 candidate galaxies at redshifts z > 6.5 and we use this sample to study the UV LF in four redshift bins between 7.5 < z < 13.5. The measured number density of galaxies at z = 8 and z = 9 matches those of past observations undertaken by the Hubble Space Telescope (HST). Our z = 10.5 measurements lie between early James Webb Space Telescope (JWST) results and past HST results, indicating cosmic variance may be the cause of previous high density measurements. However, the number densities of UV-luminous galaxies at z = 12.5 are high compared to predictions from simulations. When examining the star formation rate density of galaxies at this period, our observations are still largely consistent with a constant star formation efficiency, are slightly lower than previous early estimations using JWST, and support galaxy driven reionization at z ≤ 8.

The universal power spectrum of quasars in optical wavelengths

Context. The optical variability of quasars is one of the few windows through which we can explore the behaviour of accretion discs around supermassive black holes. Aims. We aim to establish the dependence of variability properties, such as characteristic timescales and the variability amplitude, on basic quasar parameters such as black hole mass and the accretion rate, controlling for the rest-frame wavelength of emission. Methods. Using large catalogues of quasars, we selected the g-band light curves for 4770 objects from the Zwicky Transient Facility archive. All the selected objects fall into a narrow redshift bin, 0.6 &lt; z &lt; 0.7, but cover a wide range of accretion rates in Eddington units (REdd) and black hole masses (M). We grouped these objects into 26 independent bins according to these parameters, calculated low-resolution g-band variability power spectra for each of these bins, and approximated the power spectra with a simple analytic model that features a break at a timescale, tb. Results. We find a clear dependence of the break timescale, tb, on REdd, on top of the known dependence of tb on the black hole mass, M. In our fits, tb ∝ M0.65 − 0.55REdd0.35−0.3, where the ranges in the exponents correspond to the best-fitting parameters of different power spectrum models. This mass dependence is slightly steeper than that found in other studies. Scaling tb to the orbital timescale of the innermost stable circular orbit (ISCO), tISCO, results approximately in tb/tISCO ∝ (REdd/M)0.35. In the standard thin disc model, (REdd/M) ∝ Tmax4, where Tmax is the maximum disc temperature, so that tb/tISCO appears to scale approximately with the maximum temperature of the disc to a small power. The observed values of tb are ∼10 longer than the orbital timescale at the light-weighted average radius of the disc region emitting in the (observer frame) g-band. The different scaling of the break frequency with M and REdd shows that the shape of the variability power spectrum cannot be solely a function of the quasar luminosity, even for a single rest-frame wavelength. Finally, the best-fitting models have slopes above the break in the range between −2.5 and −3. A slope of −2, as in the damped random walk models, fits the data significantly worse.

Modes of the Dark Ages 21 cm field accessible to a lunar radio interferometer.

At redshifts beyond [Formula: see text], the 21 cm line from neutral hydrogen is expected to be essentially the only viable probe of the three-dimensional matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target this signal, as it is protected from terrestrial radio frequency interference, and has no ionosphere to attenuate and absorb radio emission at low frequencies (tens of MHz and below). We forecast the sensitivity of low-frequency lunar radio arrays to the bispectrum of the 21 cm brightness temperature field, which can in turn be used to probe primordial non-Gaussianity generated by particular early universe models. We account for the loss of particular regions of Fourier space due to instrumental limitations and systematic effects, and predict the sensitivity of different representative array designs to local-type non-Gaussianity in the bispectrum, parametrized by [Formula: see text]. Under the most optimistic assumption of sample variance-limited observations, we find that [Formula: see text] could be achieved for several broad redshift bins at [Formula: see text] if foregrounds can be removed effectively. These values degrade to between [Formula: see text] and 0.7 for [Formula: see text] to [Formula: see text], respectively, when a large foreground wedge region is excluded. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Putting flat [formula omitted]CDM in the (Redshift) bin

Flat ΛCDM cosmology is specified by two constant fitting parameters at the background level in the late Universe, the Hubble constant H0 and matter density (today) Ωm. Mathematically, H0 and Ωm are either integration constants arising from solving ordinary differential equations or are directly related to integration constants. Seen in this context, if fits of the ΛCDM model to cosmological probes at different redshifts lead to different (H0,Ωm) parameters, this is a mismatch between mathematics and observation. Here, in mock observational Hubble data (OHD) (geometric probes of expansion history) we demonstrate evolution in distributions of best fit parameters with effective redshift. As a result, considerably different (H0,Ωm) best fits from Planck-ΛCDM cannot be precluded in high redshift bins. We explore if OHD, Type Ia supernovae and standardisable quasar samples exhibit redshift evolution of best fit ΛCDM parameters. In all samples, we confirm a decreasing H0 and increasing Ωm trend with increasing bin redshift. Through comparison with mocks, we confirm that similar behaviour can arise randomly within the flat ΛCDM model with probabilities as low as p=0.0021 (3.1σ). We present complementary profile distribution analysis confirming the shifts in cosmological parameters in high redshift bins. In particular, we identify a redshift range where Planck (H0,Ωm) values are disfavoured at 99.6% (2.9σ) confidence level in a combination of OHD and supernovae data.

Absence of radio-bright dominance in a near-infrared selected sample of red quasars

Context. The dichotomy between red and blue quasars is still an open question. It is debated whether red quasars are simply blue quasars that are observed at certain inclination angles or if they provide insight into a transitional phase in the evolution of quasars. Aims. We investigate the relation between quasar colors and radio-detected fraction because radio observations of quasars provide a powerful tool in distinguishing between quasar models. Methods. We present the eHAQ+GAIA23 sample, which contains quasars from the High A(V) Quasar (HAQ) Survey, the Extended High A(V) Quasar (eHAQ) Survey, and the Gaia quasar survey. All quasars in this sample have been found using a near-infrared color selection of target candidates that have otherwise been missed by the Sloan Digital Sky Survey (SDSS). We implemented a redshift-dependent color cut in g* − i* to select red quasars in the sample and divided them into redshift bins, while using a nearest-neighbors algorithm to control for luminosity and redshift differences between our red quasar sample and a selected blue sample from the SDSS. Within each bin, we cross-matched the quasars to the Faint Images of the Radio Sky at Twenty centimeters (FIRST) survey and determined the radio-detection fraction. Results. For redshifts 0.8 &lt; z ≤ 1.5, the red and blue quasars have a radio-detection fraction of 0.153−0.032+0.037 and 0.132−0.030+0.034, respectively. The red and blue quasars with redshifts 1.5 &lt; z ≤ 2.4 have radio-detection fractions of 0.059−0.016+0.019 and 0.060−0.016+0.019, respectively, and the red and blue quasars with redshifts z &gt; 2.4 have radio-detection fractions of 0.029−0.012+0.017 and 0.058−0.019+0.024, respectively. For the WISE color-selected red quasars, we find a radio-detection fraction of 0.160−0.034+0.038 for redshifts 0.8 &lt; z ≤ 1.5, 0.063−0.017+0.020 for redshifts 1.5 &lt; z ≤ 2.4, and 0.051−0.022+0.030 for redshifts z &gt; 2.4. In other words, we find similar radio-detection fractions for red and blue quasars within &lt; 1σ uncertainty, independent of redshift. This disagrees with what has been found in the literature for red quasars in SDSS. It should be noted that the fraction of broad absorption line (BAL) quasars in red SDSS quasars is about five times lower. BAL quasars have been observed to be more frequently radio quiet than other quasars, therefore the difference in BAL fractions could explain the difference in radio-detection fraction. Conclusions. The dusty torus of a quasar is transparent to radio emission. When we do not observe a difference between red and blue quasars, it leads us to argue that orientation is the main cause of quasar redness. Moreover, the observed higher proportion of BAL quasars in our dataset relative to the SDSS sample, along with the higher rate of radio detections, indicates an association of the redness of quasars and the inherent BAL fraction within the overall quasar population. This correlation suggests that the redness of quasars is intertwined with the inherent occurrence of BAL quasars within the entire population of quasars. In other words, the question why some quasars appear red or exhibit BAL characteristics might not be isolated; it could be directly related to the overall prevalence of BAL quasars in the quasar population. This finding highlights the need to explore the underlying factors contributing to both the redness and the frequency of BAL quasars, as they appear to be interconnected phenomena.

Galaxies Going Bananas: Inferring the 3D Geometry of High-redshift Galaxies with JWST-CEERS

The 3D geometries of high-redshift galaxies remain poorly understood. We build a differentiable Bayesian model and use Hamiltonian Monte Carlo to efficiently and robustly infer the 3D shapes of star-forming galaxies in James Webb Space Telescope Cosmic Evolution Early Release Science observations with logM*/M⊙=9.0–10.5 at z = 0.5–8.0. We reproduce previous results from the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey in a fraction of the computing time and constrain the mean ellipticity, triaxiality, size, and covariances with samples as small as ∼50 galaxies. We find high 3D ellipticities for all mass–redshift bins, suggesting oblate (disky) or prolate (elongated) geometries. We break that degeneracy by constraining the mean triaxiality to be ∼1 for logM*/M⊙=9.0–9.5 dwarfs at z > 1 (favoring the prolate scenario), with significantly lower triaxialities for higher masses and lower redshifts indicating the emergence of disks. The prolate population traces out a “banana” in the projected b/a–loga diagram with an excess of low-b/a, large- loga galaxies. The dwarf prolate fraction rises from ∼25% at z = 0.5–1.0 to ∼50%–80% at z = 3–8. Our results imply a second kind of disk settling from oval (triaxial) to more circular (axisymmetric) shapes with time. We simultaneously constrain the 3D size–mass relation and its dependence on 3D geometry. High-probability prolate and oblate candidates show remarkably similar Sérsic indices (n ∼ 1), nonparametric morphological properties, and specific star formation rates. Both tend to be visually classified as disks or irregular, but edge-on oblate candidates show more dust attenuation. We discuss selection effects, follow-up prospects, and theoretical implications.

The rise and fall of dust in the Universe

ABSTRACT We estimate how the mean density of dust in the Universe varies with redshift, using submillimetre continuum observations and a method designed to minimize the effect of dust temperature. We have used the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) to show that the median temperature of dust in galaxies is $\simeq 22\ \mathrm{ K}$ and does not vary significantly with redshift out to z = 1. With this as our estimate of the mass-weighted dust temperature, we have used an 850-μm survey of the field of the Cosmological Evolution Survey (COSMOS) to estimate the mean density of dust in 10 redshift bins over the range 0 &amp;lt; z &amp;lt; 5.5. We find that the mean density of dust increased by a factor of ≃10 from z = 5 to z = 2, declined slightly to z = 1, and then steeply to the present day. The relationship between the mean density of dust and redshift is similar to the relationship between the mean star formation rate and redshift, although the increase for the former is steeper from z = 5 to z = 2. We have also used the submillimetre measurements to estimate the mean density of gas over the same redshift range. The values we estimate for the dust-traced gas are much lower and with a different redshift dependence than those for estimates of the mean density of atomic gas but similar to those for estimates of the mean density of the CO-traced gas. We find that the depletion time for the dust-traced gas in the Universe as a whole declines with redshift in the same way as seen for individual galaxies.

Early dark energy constraints with late-time expansion marginalization

Early dark energy (EDE) is an extension to the ΛCDM model that includes an additional energy density contribution near recombination. The model was proposed to reduce the tension between the measurements of the Hubble constant H 0 from the cosmic microwave background (CMB) and from the local cosmic distance ladder. Some analyses in the recent literature have shown intriguing hints for EDE. However, this model increases the tension in the derived clustering of galaxies (as measured by the so-called S 8 parameter) between CMB and large scale structure (LSS) measurements. This new tension limits the contribution of EDE during recombination, and thus its effect on the Hubble tension. In this work, we investigate whether the inclusion of a general, smooth late-time dark energy modification can increase back the EDE contribution when LSS data is included in the analysis. In order to generalize the late expansion with respect to the ΛCDM model, we substitute the cosmological constant by a late dark energy fluid model with a piecewise constant equation of state w(z) in redshift bins. We show that, when analysing this generalized model with combinations of CMB, LSS and type Ia supernovae data from several experiments no significant changes on S 8 and EDE parameter constraints is found. The contribution to the EDE fraction constraint with late-time expansion marginalization is f EDE = 0.067+0.019 -0.027 using 3 redshift bins, with similar results for 5 and 10 redshift bins. This work shows that in order to solve simultaneously the Hubble and S 8 tensions, one needs a mechanism for increasing the clustering of matter at late times different from a simple change in the background evolution of late dark energy.

Covering factor in AGNs: Evolution versus selection

Aims. In every proposed unification scheme for active galactic nuclei (AGNs), an integral element is the presence of circumnuclear dust arranged in torus-like structures, partially obscuring the nuclear (accretion-associated) radiation. A crucial model parameter in this context is the covering factor (CF), which can be defined as the ratio of the infrared luminosity of the dusty torus, LIR, to the accretion disk bolometric luminosity, Lagn. Recent research has discussed the potential redshift evolution of the CF. Our study aims to determine whether this observed evolution is genuine or if selection effects significantly influence it. Methods. Based on cross-matched multiwavelength photometrical data from the five major surveys (SDSS, GALEX, UKIDSS, WISE, Spitzer), a sample of over 17 000 quasars was derived. The main parameters of quasars, such as black hole masses and the Eddington ratios, were calculated based on the spectroscopic data. The data were divided into two redshift bins: low-z quasars (redshift from 0.7 to 1.1) and high-z quasars (from 2.0 to 2.4). The associated smaller datasets with higher quality data were constructed from the WISE W3 and W4 detections with S/N &gt; 5 and the Spitzer MIPS 24 μm photometry. The CF was determined by computing the ratio of integrated luminosities, LIR and Lagn, using two methods: power-law fitting and the area between all photometric points. We explored different selection effects and their influence on CF estimates. Finally, statistical tests were employed to assess the hypothesis of CF evolution within the higher-quality datasets. Results. We identified an issue with the accuracy of the WISE W4 filter. Whenever feasible, it is recommended to utilize Spitzer MIPS 24 μm data. Luminosities obtained through direct integration of all photometric data points exhibit higher accuracy compared to values derived from a power-law approximation. The Efron &amp; Petrosian test confirmed the presence of luminosity evolution with redshift for both LIR and Lagn. The low-z and high-z samples both exhibit a similar correlation between Lagn and LIR. The calculated median CF values are comparable within the errors: log CFlow-z = −0.18 ± 0.11 and log CFhigh-z = −0.01 ± 0.13. Additionally, the Spitzer photometry dataset reinforces this consistency with log CFlow-z = −0.19 ± 0.11 and log CFhigh-z = −0.18 ± 0.11. Conclusions. No discernible evolution of the CF was observed in the subsample of quasars with high supermassive black hole (SMBH) mass bin or high luminosities, as the CF values for low-z and high-z quasars have the same distributions. The relationship between LIR and Lagn deviates slightly from the expected 1:1 scaling, suggesting a more intricate connection between CF and Lagn. However, no statistically significant dependence of CF on luminosities could be claimed across the entire dataset (merged redshifts). It is worth noting that the low-z/low-luminosity portion of the CF distribution is influenced by contamination, possibly due to polar dust, as suggested in the literature, while the high-z/high-luminosity segment is affected by observational biases.

Model independent dark matter properties from cosmic growth

Dark matter dominates the matter budget of the universe but its nature is unknown. Deviations from the standard model, where dark matter clusters with the same gravitational strength as baryons, and has the same pressureless equation of state as baryons, can be tested by cosmic growth measurements. We take a model independent approach, allowing deviations in bins of redshift, and compute the constraints enabled by ongoing cosmic structure surveys through redshift space distortions and peculiar velocities. These can produce constraints at the 3-14% level in four independent redshift bins over z = [0,4].

The mass distribution in the outskirts of clusters of galaxies as a probe of the theory of gravity

We show that ς, the radial location of the minimum in the differential radial mass profile M′(r) of a galaxy cluster, can probe the theory of gravity. We derived M′(r) of the dark matter halos of galaxy clusters from N-body cosmological simulations that implement two different theories of gravity: standard gravity in the ΛCDM model, and f(R). We extracted 49 169 dark matter halos in 11 redshift bins in the range 0 ≤ z ≤ 1 and in three different mass bins in the range 0.9 &lt; M200c/1014 h−1 M⊙ &lt; 11. We investigated the correlation of ς with the redshift and the mass accretion rate (MAR) of the halos. We show that ς decreases from ∼3R200c to ∼2R200c when z increases from 0 to 1 in the ΛCDM model. At z ∼ 0.1, ς decreases from 2.8R200c to ∼2.5R200c when the MAR increases from ∼104 h−1 M⊙ yr−1 to ∼2 × 105 h−1 M⊙ yr−1. In the f(R) model, ς is ∼15% larger than in ΛCDM. The median test shows that for samples of ≳400 dark matter halos at z ≤ 0.8, ς is able to distinguish between the two theories of gravity with a p-value ≲10−5. Upcoming advanced spectroscopic and photometric programs will allow a robust estimation of the mass profile of enormous samples of clusters up to large clustercentric distances. These samples will allow us to statistically exploit ς as probe of the theory of gravity, which complements other large-scale probes.

Cosmology from weak lensing peaks and minima with Subaru Hyper Suprime-Cam Survey first-year data

ABSTRACT We present cosmological constraints derived from peak counts, minimum counts, and the angular power spectrum of the Subaru Hyper Suprime-Cam first-year (HSC Y1) weak lensing shear catalogue. Weak lensing peak and minimum counts contain non-Gaussian information and hence are complementary to the conventional two-point statistics in constraining cosmology. In this work, we forward-model the three summary statistics and their dependence on cosmology, using a suite of N-body simulations tailored to the HSC Y1 data. We investigate systematic and astrophysical effects including intrinsic alignments, baryon feedback, multiplicative bias, and photometric redshift uncertainties. We mitigate the impact of these systematics by applying cuts on angular scales, smoothing scales, signal-to-noise ratio bins, and tomographic redshift bins. By combining peaks, minima, and the power spectrum, assuming a flat-ΛCDM model, we obtain $S_{8} \equiv \sigma _8\sqrt{\Omega _m/0.3}= 0.810^{+0.022}_{-0.026}$, a 35 per cent tighter constraint than that obtained from the angular power spectrum alone. Our results are in agreement with other studies using HSC weak lensing shear data, as well as with Planck 2018 cosmology and recent CMB lensing constraints from the Atacama Cosmology Telescope and the South Pole Telescope.

Improving precision and accuracy in cosmology with model-independent spectrum and bispectrum

A new and promising avenue was recently developed for analyzing large-scale structure data with a model-independent approach, in which the linear power spectrum shape is parametrized with a large number of freely varying wavebands rather than by assuming specific cosmological models. We call this method FreePower. Here we show, using a Fisher matrix approach, that precision of this method for the case of the one-loop power spectrum is greatly improved with the inclusion of the tree-level bispectrum. We also show that accuracy can be similarly improved by employing perturbation theory kernels whose structure is entirely determined by symmetries instead of evolution equations valid in particular models (like in the usual Einstein-de Sitter approximation). The main result is that with the Euclid survey one can precisely measure the Hubble function, distance and (k-independent) growth rate f(z) in seven redshift bins in the range z ∈ [0.6, 2.0]. The typical errors for the lower zbins are around 1% (for H), 0.7–1% (for D), and 2–3% (for f). The use of general perturbation theory allows us, for the first time, to study constraints on the nonlinear kernels of cosmological perturbations, that is, beyond the linear growth factor, showing that they can be probed at the 10–20% level. We find that the combination of spectrum and bispectrum is particularly effective in constraining the perturbation parameters, both at linear and quadratic order.

Cosmological constraints from the tomography of DES-Y3 galaxies with CMB lensing from ACT DR4

We present a measurement of the cross-correlation between the MagLim galaxies selected from the Dark Energy Survey (DES) first three years of observations (Y3) and cosmic microwave background (CMB) lensing from the Atacama Cosmology Telescope (ACT) Data Release 4 (DR4), reconstructed over ∼ 436 deg2 of the sky. Our galaxy sample, which covers ∼ 4143 deg2, is divided into six redshift bins spanning the redshift range of 0.20<z<1.05. We adopt a blinding procedure until passing all consistency and systematics tests. After imposing scale cuts for the cross-power spectrum measurement, we reject the null hypothesis of no correlation at 9.1σ. We constrain cosmological parameters from a joint analysis of galaxy and CMB lensing-galaxy power spectra considering a flat ΛCDM model, marginalized over 23 astrophysical and systematic nuisance parameters. We find the clustering amplitude S 8 ≡ σ 8(Ω m /0.3)0.5 = 0.75+0.04 -0.05. In addition, we constrain the linear growth of cosmic structure as a function of redshift. Our results are consistent with recent DES Y3 analyses and suggest a preference for a lower S 8 compared to results from measurements of CMB anisotropies by the Planck satellite, although at a mild level (< 2σ) of statistical significance.

Modified gravity and massive neutrinos: constraints from the full shape analysis of BOSS galaxies and forecasts for Stage IV surveys

We constrain the growth index γ by performing a full-shape analysis of the power spectrum multipoles measured from the BOSS DR12 data. We adopt a theoretical model based on the Effective Field theory of the Large Scale Structure (EFTofLSS) and focus on two different cosmologies: γCDM and γνCDM, where we also vary the total neutrino mass. We explore different choices for the priors on the primordial amplitude As and spectral index ns , finding that informative priors are necessary to alleviate degeneracies between the parameters and avoid strong projection effects in the posterior distributions. Our tightest constraints are obtained with 3σ Planck priors on As and ns : we obtain γ = 0.647 ± 0.085 for γCDM and γ = 0.612+0.075 -0.090, Mν < 0.30 for γνCDM at 68% c.l., in both cases ∼ 1σ consistent with the ΛCDM prediction γ ≃ 0.55. Additionally, we produce forecasts for a Stage-IV spectroscopic galaxy survey, focusing on a DESI-like sample. We fit synthetic data-vectors for three different galaxy samples generated at three different redshift bins, both individually and jointly. Focusing on the constraining power of the Large Scale Structure alone, we find that forthcoming data can give an improvement of up to ∼ 85% in the measurement of γ with respect to the BOSS dataset when no CMB priors are imposed. On the other hand, we find the neutrino mass constraints to be only marginally better than the current ones, with future data able to put an upper limit of Mν < 0.27 eV. This result can be improved with the inclusion of Planck priors on the primordial parameters, which yield Mν < 0.18 eV.