Interactions of large inorganic polyanions along a positively charged Langmuir film of dimethyldioctadecylammonium bromide were studied by Brewster angle microscopy (BAM). Because of their large size ...(>10 Å) and high refractive index, their adsorption along the organic monolayer induces an increase of the interface reflectivity and can be directly monitored by BAM. Furthermore, they strongly modify the morphology of the film and a coexistence of three phases (gaseous, liquid expanded, and liquid condensed) is easily obtained at a temperature close to 20 °C. Around this “triple point”, nucleation of liquid-condensed domains is observed along the gaseous/liquid-expanded interface, inducing unusual structures such as strings of liquid-expanded domains. Those experiments demonstrate that inorganic/organic Langmuir films based on the semiamphiphilic ionic association could present a variety of morphologies as rich as those of classical amphiphilic molecules at the gas/water interface.
We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and the Kilo-Degree Survey (KiDS-1000) in a collaborative effort between the two survey teams. We find consistent ...cosmological parameter constraints between DES Y3 and KiDS-1000 which, when combined in a joint-survey analysis, constrain the parameter S8=σ8√(Ωm/0.3) with a mean value of 0.790 +0.018 −0.014. The mean marginal is lower than the maximum a posteriori estimate, S8=0.801, owing to skewness in the marginal distribution and projection effects in the multi-dimensional parameter space. Our results are consistent with S8 constraints from observations of the cosmic microwave background by Planck, with agreement at the 1.7σ level. We use a Hybrid analysis pipeline, defined from a mock survey study quantifying the impact of the different analysis choices originally adopted by each survey team. We review intrinsic alignment models, baryon feedback mitigation strategies, priors, samplers and models of the non-linear matter power spectrum.
We used a simulation model to estimate the economic opportunity costs and the density of large stems retained for patch retention in two temperate oak stands representative of the oak/hickory forest ...type in the eastern United States. Opportunity/retention costs ranged from $321.0 to $760.7/ha $129.9 to $307.8/acre depending on the species mix in the stand, the logging technology used, and rotation lengths. The resulting capital recovery costs ranged from $12.8 to $30.4/ha/year $5.2 to $12.3/acre/year depending on the degree of retention desired, the logging technology used, and the species composition of the tract. Opportunity/capital recovery costs are greatest in stands that have high-value species mix, are harvested with low-cost logging technologies, and/or managed on longer rotations. The approach described in this paper can be used to help forest landowners, managers, loggers, and other decision/policy makers understand the opportunity/capital recovery costs and ecological benefits associated with patch retention.
We present galaxy-galaxy lensing measurements using a sample of low surface brightness galaxies (LSBGs) drawn from the Dark Energy Survey Year 3 (Y3) data as lenses. LSBGs are diffuse galaxies with a ...surface brightness dimmer than the ambient night sky. These dark-matter-dominated objects are intriguing due to potentially unusual formation channels that lead to their diffuse stellar component. Given the faintness of LSBGs, using standard observational techniques to characterize their total masses proves challenging. Weak gravitational lensing, which is less sensitive to the stellar component of galaxies, could be a promising avenue to estimate the masses of LSBGs. Our LSBG sample consists of 23,790 galaxies separated into red and blue color types at \(g-i\ge 0.60\) and \(g-i< 0.60\), respectively. Combined with the DES Y3 shear catalog, we measure the tangential shear around these LSBGs and find signal-to-noise ratios of 6.67 for the red sample, 2.17 for the blue sample, and 5.30 for the full sample. We use the clustering redshifts method to obtain redshift distributions for the red and blue LSBG samples. Assuming all red LSBGs are satellites, we fit a simple model to the measurements and estimate the host halo mass of these LSBGs to be \(\log(M_{\rm host}/M_{\odot}) = 12.98 ^{+0.10}_{-0.11}\). We place a 95% upper bound on the subhalo mass at \(\log(M_{\rm sub}/M_{\odot})<11.51\). By contrast, we assume the blue LSBGs are centrals, and place a 95% upper bound on the halo mass at \(\log(M_\mathrm{host}/M_\odot) < 11.84\). We find that the stellar-to-halo mass ratio of the LSBG samples is consistent with that of the general galaxy population. This work illustrates the viability of using weak gravitational lensing to constrain the halo masses of LSBGs.
Characterization of the redshift distribution of ensembles of galaxies is pivotal for large scale structure cosmological studies. In this work, we focus on improving the Self-Organizing Map (SOM) ...methodology for photometric redshift estimation (SOMPZ), specifically in anticipation of the Dark Energy Survey Year 6 (DES Y6) data. This data set, featuring deeper and fainter galaxies than DES Year 3 (DES Y3), demands adapted techniques to ensure accurate recovery of the underlying redshift distribution. We investigate three strategies for enhancing the existing SOM-based approach used in DES Y3: 1) Replacing the Y3 SOM algorithm with one tailored for redshift estimation challenges; 2) Incorporating \(\textit{g}\)-band flux information to refine redshift estimates (i.e. using \(\textit{griz}\) fluxes as opposed to only \(\textit{riz}\)); 3) Augmenting redshift data for galaxies where available. These methods are applied to DES Y3 data, and results are compared to the Y3 fiducial ones. Our analysis indicates significant improvements with the first two strategies, notably reducing the overlap between redshift bins. By combining strategies 1 and 2, we have successfully managed to reduce redshift bin overlap in DES Y3 by up to 66\(\%\). Conversely, the third strategy, involving the addition of redshift data for selected galaxies as an additional feature in the method, yields inferior results and is abandoned. Our findings contribute to the advancement of weak lensing redshift characterization and lay the groundwork for better redshift characterization in DES Year 6 and future stage IV surveys, like the Rubin Observatory.
The residuals of the distance moduli of Type Ia supernovae (SN Ia) relative to a Hubble diagram fit contain information about the inhomogeneity of the universe, due to weak lensing magnification by ...foreground matter. By correlating the residuals of the Dark Energy Survey Year 5 SN Ia sample (DES-SN5YR) with extra-galactic foregrounds from the DES Y3 Gold catalog, we detect the presence of lensing at \(6.0 \sigma\) significance. This is the first detection with a significance level above \(5\sigma\). Constraints on the effective mass-to-light ratios and radial profiles of dark-matter haloes surrounding individual galaxies are also obtained. We show that the scatter of SNe Ia around the Hubble diagram is reduced by modifying the standardisation of the distance moduli to include an easily calculable de-lensing (i.e., environmental) term. We use the de-lensed distance moduli to recompute cosmological parameters derived from SN Ia, finding in Flat \(w\)CDM a difference of \(\Delta \Omega_{\rm M} = +0.036\) and \(\Delta w = -0.056\) compared to the unmodified distance moduli, a change of \(\sim 0.3\sigma\). We argue that our modelling of SN Ia lensing will lower systematics on future surveys with higher statistical power. We use the observed dispersion of lensing in DES-SN5YR to constrain \(\sigma_8\), but caution that the fit is sensitive to uncertainties at small scales. Nevertheless, our detection of SN Ia lensing opens a new pathway to study matter inhomogeneity that complements galaxy-galaxy lensing surveys and has unrelated systematics.
We present a Bayesian population modeling method to analyze the abundance of galaxy clusters identified by the South Pole Telescope (SPT) with a simultaneous mass calibration using weak gravitational ...lensing data from the Dark Energy Survey (DES) and the Hubble Space Telescope (HST). We discuss and validate the modeling choices with a particular focus on a robust, weak-lensing-based mass calibration using DES data. For the DES Year 3 data, we report a systematic uncertainty in weak-lensing mass calibration that increases from 1% at \(z=0.25\) to 10% at \(z=0.95\), to which we add 2% in quadrature to account for uncertainties in the impact of baryonic effects. We implement an analysis pipeline that joins the cluster abundance likelihood with a multi-observable likelihood for the Sunyaev-Zel'dovich effect, optical richness, and weak-lensing measurements for each individual cluster. We validate that our analysis pipeline can recover unbiased cosmological constraints by analyzing mocks that closely resemble the cluster sample extracted from the SPT-SZ, SPTpol ECS, and SPTpol 500d surveys and the DES Year 3 and HST-39 weak-lensing datasets. This work represents a crucial prerequisite for the subsequent cosmological analysis of the real dataset.
We present the angular diameter distance measurement obtained with the
Baryonic Acoustic Oscillation feature from galaxy clustering in the completed
Dark Energy Survey, consisting of six years (Y6) ...of observations. We use the Y6
BAO galaxy sample, optimized for BAO science in the redshift range 0.6<$z$<1.2,
with an effective redshift at $z_{\rm eff}$=0.85 and split into six tomographic
bins. The sample has nearly 16 million galaxies over 4,273 square degrees. Our
consensus measurement constrains the ratio of the angular distance to sound
horizon scale to $D_M(z_{\rm eff})/r_d$ = 19.51$\pm$0.41 (at 68.3% confidence
interval), resulting from comparing the BAO position in our data to that
predicted by Planck $\Lambda$CDM via the BAO shift parameter
$\alpha=(D_M/r_d)/(D_M/r_d)_{\rm Planck}$. To achieve this, the BAO shift is
measured with three different methods, Angular Correlation Function (ACF),
Angular Power Spectrum (APS), and Projected Correlation Function (PCF)
obtaining $\alpha=$ 0.952$\pm$0.023, 0.962$\pm$0.022, and 0.955$\pm$0.020,
respectively, which we combine to $\alpha=$ 0.957$\pm$0.020, including
systematic errors. When compared with the $\Lambda$CDM model that best fits
Planck data, this measurement is found to be 4.3% and 2.1$\sigma$ below the
angular BAO scale predicted. To date, it represents the most precise angular
BAO measurement at $z$>0.75 from any survey and the most precise measurement at
any redshift from photometric surveys. The analysis was performed blinded to
the BAO position and it is shown to be robust against analysis choices, data
removal, redshift calibrations and observational systematics.
