58 research outputs found
Dark Energy Survey Year 3 results: Magnification modeling and impact on cosmological constraints from galaxy clustering and galaxy-galaxy lensing
We study the effect of magnification in the Dark Energy Survey Year 3
analysis of galaxy clustering and galaxy-galaxy lensing, using two different
lens samples: a sample of Luminous red galaxies, redMaGiC, and a sample with a
redshift-dependent magnitude limit, MagLim. We account for the effect of
magnification on both the flux and size selection of galaxies, accounting for
systematic effects using the Balrog image simulations. We estimate the impact
of magnification on the galaxy clustering and galaxy-galaxy lensing cosmology
analysis, finding it to be a significant systematic for the MagLim sample. We
show cosmological constraints from the galaxy clustering auto-correlation and
galaxy-galaxy lensing signal with different magnifications priors, finding
broad consistency in cosmological parameters in CDM and CDM.
However, when magnification bias amplitude is allowed to be free, we find the
two-point correlations functions prefer a different amplitude to the fiducial
input derived from the image simulations. We validate the magnification
analysis by comparing the cross-clustering between lens bins with the
prediction from the baseline analysis, which uses only the auto-correlation of
the lens bins, indicating systematics other than magnification may be the cause
of the discrepancy. We show adding the cross-clustering between lens redshift
bins to the fit significantly improves the constraints on lens magnification
parameters and allows uninformative priors to be used on magnification
coefficients, without any loss of constraining power or prior volume concerns.Comment: 21 pages, 13 figures, See this
https://www.darkenergysurvey.org/des-year-3-cosmology-results-papers/ URL for
the full DES Y3 cosmology releas
Detection of the significant impact of source clustering on higher-order statistics with DES Year 3 weak gravitational lensing data
We measure the impact of source galaxy clustering on higher-order summary statistics of weak gravitational lensing data. By comparing simulated data with galaxies that either trace or do not trace the underlying density field, we show this effect can exceed measurement uncertainties for common higher-order statistics for certain analysis choices. We evaluate the impact on different weak lensing observables, finding that third moments and wavelet phase harmonics are more affected than peak count statistics. Using Dark Energy Survey Year 3 data we construct null tests for the source-clustering-free case, finding a p-value of p = 4 × 10−3 (2.6σ) using third-order map moments and p = 3 × 10−11 (6.5σ) using wavelet phase harmonics. The impact of source clustering on cosmological inference can be either be included in the model or minimized through ad-hoc procedures (e.g. scale cuts). We verify that the procedures adopted in existing DES Y3 cosmological analyses were sufficient to render this effect negligible. Failing to account for source clustering can significantly impact cosmological inference from higher-order gravitational lensing statistics, e.g. higher-order N-point functions, wavelet-moment observables, and deep learning or field level summary statistics of weak lensing maps
Detection of the significant impact of source clustering on higher-order statistics with DES Year 3 weak gravitational lensing data
We demonstrate and measure the impact of source galaxy clustering on
higher-order summary statistics of weak gravitational lensing data. By
comparing simulated data with galaxies that either trace or do not trace the
underlying density field, we show this effect can exceed measurement
uncertainties for common higher-order statistics for certain analysis choices.
Source clustering effects are larger at small scales and for statistics applied
to combinations of low and high redshift samples, and diminish at high
redshift. We evaluate the impact on different weak lensing observables, finding
that third moments and wavelet phase harmonics are more affected than peak
count statistics. Using Dark Energy Survey Year 3 data we construct null tests
for the source-clustering-free case, finding a -value of
(2.6 ) using third-order map moments and (6.5
) using wavelet phase harmonics. The impact of source clustering on
cosmological inference can be either be included in the model or minimized
through \textit{ad-hoc} procedures (e.g. scale cuts). We verify that the
procedures adopted in existing DES Y3 cosmological analyses (using map moments
and peaks) were sufficient to render this effect negligible. Failing to account
for source clustering can significantly impact cosmological inference from
higher-order gravitational lensing statistics, e.g. higher-order N-point
functions, wavelet-moment observables (including phase harmonics and scattering
transforms), and deep learning or field level summary statistics of weak
lensing maps. We provide recipes both to minimise the impact of source
clustering and to incorporate source clustering effects into forward-modelled
mock data.Comment: 5 pages, 2 figures, submitted to MNRAS Letter
Non-local contribution from small scales in galaxy-galaxy lensing: Comparison of mitigation schemes
Recent cosmological analyses with large-scale structure and weak lensing
measurements, usually referred to as 32pt, had to discard a lot of
signal-to-noise from small scales due to our inability to precisely model
non-linearities and baryonic effects. Galaxy-galaxy lensing, or the
position-shear correlation between lens and source galaxies, is one of the
three two-point correlation functions that are included in such analyses,
usually estimated with the mean tangential shear. However, tangential shear
measurements at a given angular scale or physical scale carry
information from all scales below that, forcing the scale cuts applied in real
data to be significantly larger than the scale at which theoretical
uncertainties become problematic. Recently there have been a few independent
efforts that aim to mitigate the non-locality of the galaxy-galaxy lensing
signal. Here we perform a comparison of the different methods, including the Y
transformation described in Park et al. (2021), the point-mass marginalization
methodology presented in MacCrann et al. (2020) and the Annular Differential
Surface Density statistic described in Baldauf et al. (2010). We do the
comparison at the cosmological constraints level in a noiseless simulated
combined galaxy clustering and galaxy-galaxy lensing analysis. We find that all
the estimators perform equivalently using a Rubin Observatory Legacy Survey of
Space and Time (LSST) Year 1 like setup. This is because all the estimators
project out the mode responsible for the non-local nature of the galaxy-galaxy
lensing measurements, which we have identified as . We finally apply all
the estimators to DES Y3 data and confirm that they all give consistent
results.Comment: 9+3 pages, 3+3 figures. To be submitted to MNRA
CIBERER : Spanish national network for research on rare diseases: A highly productive collaborative initiative
Altres ajuts: Instituto de Salud Carlos III (ISCIII); Ministerio de Ciencia e Innovación.CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low-prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15-year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research
The Dark Energy Survey Year 3 and eBOSS: constraining galaxy intrinsic alignments across luminosity and colour space
We present direct constraints on galaxy intrinsic alignments using the Dark
Energy Survey Year 3 (DES Y3), the Extended Baryon Oscillation Spectroscopic
Survey (eBOSS) and its precursor, the Baryon Oscillation Spectroscopic Survey
(BOSS). Our measurements incorporate photometric red sequence (redMaGiC)
galaxies from DES with median redshift , luminous red galaxies
(LRGs) from eBOSS at , and also a SDSS-III BOSS CMASS sample at
. We measure two point intrinsic alignment correlations, which we fit
using a model that includes lensing, magnification and photometric redshift
error. Fitting on scales Mpc, we make a detection of
intrinsic alignments in each sample, at (assuming a simple
one parameter model for IAs). Using these red samples, we measure the
IA-luminosity relation. Our results are statistically consistent with previous
results, but offer a significant improvement in constraining power,
particularly at low luminosity. With this improved precision, we see detectable
dependence on colour between broadly defined red samples. It is likely that a
more sophisticated approach than a binary red/blue split, which jointly
considers colour and luminosity dependence in the IA signal, will be needed in
future. We also compare the various signal components at the best fitting point
in parameter space for each sample, and find that magnification and lensing
contribute of the total signal. As precision continues to improve,
it will certainly be necessary to account for these effects in future direct IA
measurements. Finally, we make equivalent measurements on a sample of Emission
Line Galaxies (ELGs) from eBOSS at . We report a null detection,
constraining the IA amplitude (assuming the nonlinear alignment model) to be
( at CL).Comment: Submitted to MNRAS; 22 pages, 11 figure
Dark Energy Survey Year 3 Results: Redshift Calibration of the MagLim Lens Sample from the combination of SOMPZ and clustering and its impact on Cosmology
We present an alternative calibration of the MagLim lens sample redshift
distributions from the Dark Energy Survey (DES) first three years of data (Y3).
The new calibration is based on a combination of a Self-Organising Maps based
scheme and clustering redshifts to estimate redshift distributions and inherent
uncertainties, which is expected to be more accurate than the original DES Y3
redshift calibration of the lens sample. We describe in detail the methodology,
we validate it on simulations and discuss the main effects dominating our error
budget. The new calibration is in fair agreement with the fiducial DES Y3
redshift distributions calibration, with only mild differences () in
the means and widths of the distributions. We study the impact of this new
calibration on cosmological constraints, analysing DES Y3 galaxy clustering and
galaxy-galaxy lensing measurements, assuming a CDM cosmology. We
obtain , and , which implies a shift in the
plane compared to the fiducial DES Y3 results, highlighting the importance of
the redshift calibration of the lens sample in multi-probe cosmological
analyses
DES Y3 + KiDS-1000: Consistent cosmology combining cosmic shear surveys
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 with a mean value of
. The mean marginal is lower than the maximum a
posteriori estimate, , owing to skewness in the marginal
distribution and projection effects in the multi-dimensional parameter space.
Our results are consistent with constraints from observations of the
cosmic microwave background by Planck, with agreement at the 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.Comment: 38 pages, 21 figures, 15 tables, submitted to the Open Journal of
Astrophysics. Watch the core team discuss this analysis at
https://cosmologytalks.com/2023/05/26/des-kid
SPT Clusters with DES and HST Weak Lensing. I. Cluster Lensing and Bayesian Population Modeling of Multi-Wavelength Cluster Datasets
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 to 10\% at , 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 SZ, 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.Comment: submitted to PR
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