Beyond-\(\Lambda\)CDM physics or systematic errors may cause subsets of a cosmological data set to appear inconsistent when analyzed assuming \(\Lambda\)CDM. We present an application of internal ...consistency tests to measurements from the Dark Energy Survey Year 1 (DES Y1) joint probes analysis. Our analysis relies on computing the posterior predictive distribution (PPD) for these data under the assumption of \(\Lambda\)CDM. We find that the DES Y1 data have an acceptable goodness of fit to \(\Lambda\)CDM, with a probability of finding a worse fit by random chance of \({p = 0.046}\). Using numerical PPD tests, supplemented by graphical checks, we show that most of the data vector appears completely consistent with expectations, although we observe a small tension between large- and small-scale measurements. A small part (roughly 1.5%) of the data vector shows an unusually large departure from expectations; excluding this part of the data has negligible impact on cosmological constraints, but does significantly improve the \(p\)-value to 0.10. The methodology developed here will be applied to test the consistency of DES Year 3 joint probes data sets.
Phys. Rev. D 103, 023528 (2021) We analyze Dark Energy Survey (DES) data to constrain a cosmological model
where a subset of parameters -- focusing on $\Omega_m$ -- are split into
versions associated ...with structure growth (e.g. $\Omega_m^{\rm grow}$) and
expansion history (e.g. $\Omega_m^{\rm geo}$). Once the parameters have been
specified for the $\Lambda$CDM cosmological model, which includes general
relativity as a theory of gravity, it uniquely predicts the evolution of both
geometry (distances) and the growth of structure over cosmic time. Any
inconsistency between measurements of geometry and growth could therefore
indicate a breakdown of that model. Our growth-geometry split approach
therefore serves as both a (largely) model-independent test for
beyond-$\Lambda$CDM physics, and as a means to characterize how DES observables
provide cosmological information. We analyze the same multi-probe DES data as
arXiv:1811.02375 : DES Year 1 (Y1) galaxy clustering and weak lensing, which
are sensitive to both growth and geometry, as well as Y1 BAO and Y3 supernovae,
which probe geometry. We additionally include external geometric information
from BOSS DR12 BAO and a compressed Planck 2015 likelihood, and external growth
information from BOSS DR12 RSD. We find no significant disagreement with
$\Omega_m^{\rm grow}=\Omega_m^{\rm geo}$. When DES and external data are
analyzed separately, degeneracies with neutrino mass and intrinsic alignments
limit our ability to measure $\Omega_m^{\rm grow}$, but combining DES with
external data allows us to constrain both growth and geometric quantities. We
also consider a parameterization where we split both $\Omega_m$ and $w$, but
find that even our most constraining data combination is unable to separately
constrain $\Omega_m^{\rm grow}$ and $w^{\rm grow}$. Relative to $\Lambda$CDM,
splitting growth and geometry weakens bounds on $\sigma_8$ but does not alter
constraints on $h$.
We present simulation-based cosmological \(w\)CDM inference using Dark Energy Survey Year 3 weak-lensing maps, via neural data compression of weak-lensing map summary statistics: power spectra, peak ...counts, and direct map-level compression/inference with convolutional neural networks (CNN). Using simulation-based inference, also known as likelihood-free or implicit inference, we use forward-modelled mock data to estimate posterior probability distributions of unknown parameters. This approach allows all statistical assumptions and uncertainties to be propagated through the forward-modelled mock data; these include sky masks, non-Gaussian shape noise, shape measurement bias, source galaxy clustering, photometric redshift uncertainty, intrinsic galaxy alignments, non-Gaussian density fields, neutrinos, and non-linear summary statistics. We include a series of tests to validate our inference results. This paper also describes the Gower Street simulation suite: 791 full-sky PKDGRAV dark matter simulations, with cosmological model parameters sampled with a mixed active-learning strategy, from which we construct over 3000 mock DES lensing data sets. For \(w\)CDM inference, for which we allow \(-1<w<-\frac{1}{3}\), our most constraining result uses power spectra combined with map-level (CNN) inference. Using gravitational lensing data only, this map-level combination gives \(\Omega_{\rm m} = 0.283^{+0.020}_{-0.027}\), \({S_8 = 0.804^{+0.025}_{-0.017}}\), and \(w < -0.80\) (with a 68 per cent credible interval); compared to the power spectrum inference, this is more than a factor of two improvement in dark energy parameter (\(\Omega_{\rm DE}, w\)) precision.
We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, \(\Lambda\)CDM and \(w\)CDM, by using a combined analysis of galaxy clustering and ...weak gravitational lensing from the first-year data of the Dark Energy Survey (DES Y1) in combination with external data. We consider four extensions of the minimal dark energy-dominated scenarios: 1) nonzero curvature \(\Omega_k\), 2) number of relativistic species \(N_{\rm eff}\) different from the standard value of 3.046, 3) time-varying equation-of-state of dark energy described by the parameters \(w_0\) and \(w_a\) (alternatively quoted by the values at the pivot redshift, \(w_p\), and \(w_a\)), and 4) modified gravity described by the parameters \(\mu_0\) and \(\Sigma_0\) that modify the metric potentials. We also consider external information from Planck CMB measurements; BAO measurements from SDSS, 6dF, and BOSS; RSD measurements from BOSS; and SNIa information from the Pantheon compilation. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, we find \(\Omega_k=0.0020^{+0.0037}_{-0.0032}\) at the 68% confidence level, and \(N_{\rm eff}<3.28\, (3.55)\) at 68% (95%) confidence. For the time-varying equation-of-state, we find the pivot value \((w_p, w_a)=(-0.91^{+0.19}_{-0.23}, -0.57^{+0.93}_{-1.11})\) at pivot redshift \(z_p=0.27\) from DES alone, and \((w_p, w_a)=(-1.01^{+0.04}_{-0.04}, -0.28^{+0.37}_{-0.48})\) at \(z_p=0.20\) from DES Y1 combined with external data; in either case we find no evidence for the temporal variation of the equation of state. For modified gravity, we find the present-day value of the relevant parameters to be \(\Sigma_0= 0.43^{+0.28}_{-0.29}\) from DES Y1 alone, and \((\Sigma_0, \mu_0)=(0.06^{+0.08}_{-0.07}, -0.11^{+0.42}_{-0.46})\) from DES Y1 combined with external data, consistent with predictions from GR.
We constrain extensions to the \(\Lambda\)CDM model using measurements from the Dark Energy Survey's first three years of observations and external data. The DES data are the two-point correlation ...functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. We use simulated data and blind analyses of real data to validate the robustness of our results. In many cases, constraining power is limited by the absence of nonlinear predictions that are reliable at our required precision. The models are: dark energy with a time-dependent equation of state, non-zero spatial curvature, sterile neutrinos, modifications of gravitational physics, and a binned \(\sigma_8(z)\) model which serves as a probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find \((w_{\rm p}, w_a)= (-0.99^{+0.28}_{-0.17},-0.9\pm 1.2)\) at 68% confidence with \(z_{\rm p}=0.24\) from the DES measurements alone, and \((w_{\rm p}, w_a)= (-1.03^{+0.04}_{-0.03},-0.4^{+0.4}_{-0.3})\) with \(z_{\rm p}=0.21\) for the combination of all data considered. Curvature constraints of \(\Omega_k=0.0009\pm 0.0017\) and effective relativistic species \(N_{\rm eff}=3.10^{+0.15}_{-0.16}\) are dominated by external data. For massive sterile neutrinos, we improve the upper bound on the mass \(m_{\rm eff}\) by a factor of three compared to previous analyses, giving 95% limits of \((\Delta N_{\rm eff},m_{\rm eff})\leq (0.28, 0.20\, {\rm eV})\). We also constrain changes to the lensing and Poisson equations controlled by functions \(\Sigma(k,z) = \Sigma_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}\) and \(\mu(k,z)=\mu_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}\) respectively to \(\Sigma_0=0.6^{+0.4}_{-0.5}\) from DES alone and \((\Sigma_0,\mu_0)=(0.04\pm 0.05,0.08^{+0.21}_{-0.19})\) for the combination of all data. Overall, we find no significant evidence for physics beyond \(\Lambda\)CDM.
We compare Einstein-Boltzmann solvers that include modifications to General Relativity and find that, for a wide range of models and parameters, they agree to a high level of precision. We look at ...three general purpose codes that primarily model general scalar-tensor theories, three codes that model Jordan-Brans-Dicke (JBD) gravity, a code that models f(R) gravity, a code that models covariant Galileons, a code that models Hořava-Lifschitz gravity and two codes that model non-local models of gravity. Comparing predictions of the angular power spectrum of the cosmic microwave background and the power spectrum of dark matter for a suite of different models, we find agreement at the sub-percent level. This means that this suite of Einstein-Boltzmann solvers is now sufficiently accurate for precision constraints on cosmological and gravitational parameters.
Reverberation mapping measurements have been used to constrain the relationship between the size of the broad-line region and luminosity of active galactic nuclei (AGN). This \(R-L\) relation is used ...to estimate single-epoch virial black hole masses, and has been proposed for use to standardise AGN to determine cosmological distances. We present reverberation measurements made with H\(\beta\) from the six-year Australian Dark Energy Survey (OzDES) Reverberation Mapping Program. We successfully recover reverberation lags for eight AGN at \(0.12<z< 0.71\), probing higher redshifts than the bulk of H\(\beta\) measurements made to date. Our fit to the \(R-L\) relation has a slope of \(\alpha=0.41\pm0.03\) and an intrinsic scatter of \(\sigma=0.23\pm0.02\) dex. The results from our multi-object spectroscopic survey are consistent with previous measurements made by dedicated source-by-source campaigns, and with the observed dependence on accretion rate. Future surveys, including LSST, TiDES and SDSS-V, which will be revisiting some of our observed fields, will be able to build on the results of our first-generation multi-object reverberation mapping survey.
We cross-correlate positions of galaxies measured in data from the first three years of the Dark Energy Survey with Compton-\(y\)-maps generated using data from the South Pole Telescope (SPT) and the ...{\it Planck} mission. We model this cross-correlation measurement together with the galaxy auto-correlation to constrain the distribution of gas in the Universe. We measure the hydrostatic mass bias or, equivalently, the mean halo bias-weighted electron pressure \(\langle b_{h}P_{e}\rangle\), using large-scale information. We find \(\langle b_{h}P_{e}\rangle\) to be \(0.16^{+0.03}_{-0.04},0.28^{+0.04}_{-0.05},0.45^{+0.06}_{-0.10},0.54^{+0.08}_{-0.07},0.61^{+0.08}_{-0.06},0.63^{+0.07}_{-0.08}\) meV cm\(^{-3}\) at redshifts \(z \sim 0.30, 0.46, 0.62,0.77, 0.89, 0.97\). These values are consistent with previous work where measurements exist in the redshift range. We also constrain the mean gas profile using small-scale information, enabled by the high-resolution of the SPT data. We compare our measurements to different parametrized profiles based on the cosmo-OWLS hydrodynamical simulations. We find that our data are consistent with the simulation that assumes an AGN heating temperature of \(10^{8.5}\)K but are incompatible with the model that assumes an AGN heating temperature of \(10^{8.0}\)K. These comparisons indicate that the data prefer a higher value of electron pressure than the simulations within \(r_{500c}\) of the galaxies' halos.
We characterise the properties and evolution of Bright Central Galaxies (BCGs) and the surrounding intracluster light (ICL) in galaxy clusters identified in overlapping regions of the Dark Energy ...Survey and Atacama Cosmology Telescope Survey (DES-ACT), covering the redshift range \(0.20<z<0.80\). Using this sample, we measure no change in the ICL's stellar content (between 50-300\,kpc) over this redshift range in clusters with log\(_{10}(M_{\rm 200m,SZ}\)/M\(_{\odot})>\)14.4. We also measure the stellar mass - halo mass (SMHM) relation for the BCG+ICL system and find that the slope, \(\beta\), which characterises the dependence of \(M_{\rm 200m,SZ}\) on the BCG+ICL stellar mass, increases with radius. The outskirts are more strongly correlated with the halo than the core, which supports that the BCG+ICL system follows a two-phase growth, where recent growth (\(z<2\)) occurs beyond the BCG's core. Additionally, we compare our observed SMHM relation results to the IllustrisTNG 300-1 cosmological hydrodynamic simulations and find moderate qualitative agreement in the amount of diffuse light. However, the SMHM relation's slope is steeper in TNG300-1 and the intrinsic scatter is lower, likely from the absence of projection effects in TNG300-1. Additionally, we find that the ICL exhibits a colour gradient such that the outskirts are bluer than the core. Moreover, for the lower halo mass clusters (log\(_{10}(M_{\rm 200m,SZ}\)/M\(_{\odot})<\)14.59 ), we detect a modest change in the colour gradient's slope with lookback time, which combined with the absence of stellar mass growth may suggest that lower mass clusters have been involved in growth via tidal stripping more recently than their higher mass counterparts.
We analyze Dark Energy Survey (DES) data to constrain a cosmological model where a subset of parameters -- focusing on \(\Omega_m\) -- are split into versions associated with structure growth (e.g. ...\(\Omega_m^{\rm grow}\)) and expansion history (e.g. \(\Omega_m^{\rm geo}\)). Once the parameters have been specified for the \(\Lambda\)CDM cosmological model, which includes general relativity as a theory of gravity, it uniquely predicts the evolution of both geometry (distances) and the growth of structure over cosmic time. Any inconsistency between measurements of geometry and growth could therefore indicate a breakdown of that model. Our growth-geometry split approach therefore serves as both a (largely) model-independent test for beyond-\(\Lambda\)CDM physics, and as a means to characterize how DES observables provide cosmological information. We analyze the same multi-probe DES data as arXiv:1811.02375 : DES Year 1 (Y1) galaxy clustering and weak lensing, which are sensitive to both growth and geometry, as well as Y1 BAO and Y3 supernovae, which probe geometry. We additionally include external geometric information from BOSS DR12 BAO and a compressed Planck 2015 likelihood, and external growth information from BOSS DR12 RSD. We find no significant disagreement with \(\Omega_m^{\rm grow}=\Omega_m^{\rm geo}\). When DES and external data are analyzed separately, degeneracies with neutrino mass and intrinsic alignments limit our ability to measure \(\Omega_m^{\rm grow}\), but combining DES with external data allows us to constrain both growth and geometric quantities. We also consider a parameterization where we split both \(\Omega_m\) and \(w\), but find that even our most constraining data combination is unable to separately constrain \(\Omega_m^{\rm grow}\) and \(w^{\rm grow}\). Relative to \(\Lambda\)CDM, splitting growth and geometry weakens bounds on \(\sigma_8\) but does not alter constraints on \(h\).
