518 research outputs found
Dark Energy Survey Year 1 results : cosmological constraints from cluster abundances, weak lensing, and galaxy correlations
We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4 × 2pt þ N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ωm ¼ 0.305þ0.055 −0.038 and σ8 ¼ 0.783þ0.064 −0.054 . This result is consistent with constraints from the DES-Y1 galaxy clustering and weak lensing two-point correlation functions for the flat νΛCDM model. Consequently, we combine cluster abundances and all two-point correlations from across all three cosmic tracer fields (6 × 2pt þ N) and find improved constraints on cosmological parameters as well as on the cluster observable-mass scaling relation. This analysis is an important advance in both optical cluster cosmology and multiprobe analyses of upcoming wide imaging surveys
RedMaPPer: Evolution and Mass Dependence of the Conditional Luminosity Functions of Red Galaxies in Galaxy Clusters
We characterize the luminosity distribution, halo mass dependence, and
redshift evolution of red galaxies in galaxy clusters using the SDSS Data
Release 8 RedMaPPer cluster sample. We propose a simple prescription for the
relationship between the luminosity of both central and satellite galaxies and
the mass of their host halos, and show that this model is well-fit by the data.
Using a larger galaxy cluster sample than previously employed in the
literature, we find that the luminosities of central galaxies scale as , with , and that
the scatter of the central--galaxy luminosity at fixed (
) is dex, with the error bar
including systematics due to miscentering of the cluster finder, photometry,
and photometric redshift estimation. Our data prefers a positive correlation
between the luminosity of central galaxies and the observed richness of
clusters at a fixed halo mass, with an effective correlation coefficient
. The characteristic luminosity of
satellites becomes dimmer from to by after
accounting for passive evolution. We estimate the fraction of galaxy clusters
where the brightest galaxy is not the central to be .
We discuss implications of these findings in the context of galaxy evolution
and the galaxy--halo connection.Comment: 29 pages, 17 figures, 5 tables. Accepted by AP
Dark Energy Survey Year 1 Clusters are Consistent with Planck
The recent Dark Energy Survey Year 1 (DES-Y1) analysis of galaxy cluster
abundances and weak lensing produced and
constraints in 5.6 tension with Planck. It is suggested in that work
that this tension is driven by unmodelled systematics in optical cluster
selection. We present a novel simulation-based forward modeling framework that
explicitly incorporates cluster selection into its model predictions. Applying
this framework to the DES-Y1 data we find consistency with Planck, resolving
the tension found in the DES-Y1 analysis. An extension of this approach to the
final DES data set will produce robust constraints on CDM parameters
and correspondingly strong tests of cosmological models.Comment: 6 pages, 2 figures, 1 table, Supplemental material with 2 figures.
Submitted to Physical Review Letter
Buzzard to Cardinal: Improved Mock Catalogs for Large Galaxy Surveys
We present the Cardinal mock galaxy catalogs, a new version of the Buzzard simulation that has been updated to support ongoing and future cosmological surveys, including the Dark Energy Survey (DES), DESI, and LSST. These catalogs are based on a one-quarter sky simulation populated with galaxies out to a redshift of z = 2.35 to a depth of mr = 27. Compared to the Buzzard mocks, the Cardinal mocks include an updated subhalo abundance matching model that considers orphan galaxies and includes mass-dependent scatter between galaxy luminosity and halo properties. This model can simultaneously fit galaxy clustering and group–galaxy cross-correlations measured in three different luminosity threshold samples. The Cardinal mocks also feature a new color assignment model that can simultaneously fit color-dependent galaxy clustering in three different luminosity bins. We have developed an algorithm that uses photometric data to further improve the color assignment model and have also developed a novel method to improve small-scale lensing below the ray-tracing resolution. These improvements enable the Cardinal mocks to accurately reproduce the abundance of galaxy clusters and the properties of lens galaxies in the DES data. As such, these simulations will be a valuable tool for future cosmological analyses based on large sky surveys
UNIT project: Universe -body simulations for the Investigation of Theoretical models from galaxy surveys
We present the UNIT -body cosmological simulations project, designed to
provide precise predictions for nonlinear statistics of the galaxy
distribution. We focus on characterizing statistics relevant to emission line
and luminous red galaxies in the current and upcoming generation of galaxy
surveys. We use a suite of precise particle mesh simulations (FastPM) as well
as with full -body calculations with a mass resolution of M to investigate the recently suggested
technique of Angulo & Pontzen 2016 to suppress the variance of cosmological
simulations We study redshift space distortions, cosmic voids, higher order
statistics from down to . We find that both two- and three-point
statistics are unbiased. Over the scales of interest for baryon acoustic
oscillations and redshift-space distortions, we find that the variance is
greatly reduced in the two-point statistics and in the cross correlation
between halos and cosmic voids, but is not reduced significantly for the
three-point statistics. We demonstrate that the accuracy of the two-point
correlation function for a galaxy survey with effective volume of 20
(Gpc) is improved by about a factor of 40, indicating that two
pairs of simulations with a volume of 1 (Gpc) lead to the
equivalent variance of 150 such simulations. The -body simulations
presented here thus provide an effective survey volume of about seven times the
effective survey volume of DESI or Euclid. The data from this project,
including dark matter fields, halo catalogues, and their clustering statistics,
are publicly available at http://www.unitsims.org.Comment: 12 pages, 9 figures. This version matches the one accepted by MNRAS.
The data from this project are publicly available at: http://www.unitsims.or
Covariance matrices for variance-suppressed simulations
Cosmological -body simulations provide numerical predictions of the
structure of the universe against which to compare data from ongoing and future
surveys. The growing volume of the surveyed universe, however, requires
increasingly large simulations. It was recently proposed to reduce the variance
in simulations by adopting fixed-amplitude initial conditions. This method has
been demonstrated not to introduce bias in various statistics, including the
two-point statistics of galaxy samples typically used for extracting
cosmological parameters from galaxy redshift survey data. However, we must
revisit current methods for estimating covariance matrices for these
simulations to be sure that we can properly use them. In this work, we find
that it is not trivial to construct the covariance matrix analytically, but we
demonstrate that EZmock, the most efficient method for constructing mock
catalogues with accurate two- and three-point statistics, provides reasonable
covariance matrix estimates for variance-suppressed simulations. We further
investigate the behavior of the variance suppression by varying galaxy bias,
three-point statistics, and small-scale clustering.Comment: 9 pages, 7 figure
CosmoDC2: A Synthetic Sky Catalog for Dark Energy Science with LSST
This paper introduces cosmoDC2, a large synthetic galaxy catalog designed to
support precision dark energy science with the Large Synoptic Survey Telescope
(LSST). CosmoDC2 is the starting point for the second data challenge (DC2)
carried out by the LSST Dark Energy Science Collaboration (LSST DESC). The
catalog is based on a trillion-particle, 4.225 Gpc^3 box cosmological N-body
simulation, the `Outer Rim' run. It covers 440 deg^2 of sky area to a redshift
of z=3 and is complete to a magnitude depth of 28 in the r-band. Each galaxy is
characterized by a multitude of properties including stellar mass, morphology,
spectral energy distributions, broadband filter magnitudes, host halo
information and weak lensing shear. The size and complexity of cosmoDC2
requires an efficient catalog generation methodology; our approach is based on
a new hybrid technique that combines data-driven empirical approaches with
semi-analytic galaxy modeling. A wide range of observation-based validation
tests has been implemented to ensure that cosmoDC2 enables the science goals of
the planned LSST DESC DC2 analyses. This paper also represents the official
release of the cosmoDC2 data set, including an efficient reader that
facilitates interaction with the data
Constraints on dark matter to dark radiation conversion in the late universe with DES-Y1 and external data
84siWe study a class of decaying dark matter models as a possible resolution to the observed discrepancies between early- and late-time probes of the universe. This class of models, dubbed DDM, characterizes the evolution of comoving dark matter density with two extra parameters. We investigate how DDM affects key cosmological observables such as the CMB temperature and matter power spectra. Combining 3x2pt data from Year 1 of the Dark Energy Survey,Planck-2018 CMB temperature and polarization data, Supernova (SN) Type Ia data from Pantheon, and BAO data from BOSS DR12, MGS and 6dFGS, we place new constraints on the amount of dark matter that has decayed and the rate with which it converts to dark radiation. The fraction of the decayed dark matter in units of the current amount of dark matter, , is constrained at 68% confidence level to be <0.32 for DES-Y1 3x2pt data, <0.030 for CMB+SN+BAO data, and <0.037 for the combined dataset. The probability that the DES and CMB+SN+BAO datasets are concordant increases from 4% for the CDM model to 8% (less tension) for DDM. Moreover, tension in between DES-Y1 3x2pt and CMB+SN+BAO is reduced from 2.3 to 1.9. We find no reduction in the Hubble tension when the combined data is compared to distance-ladder measurements in the DDM model. The maximum-posterior goodness-of-fit statistics of DDM and CDM are comparable, indicating no preference for the DDM cosmology over CDM....partially_openopenChen, Angela; Huterer, Dragan; Lee, Sujeong; Ferté, Agnès; Weaverdyck, Noah; Alonso Alves, Otavio; Leonard, C. Danielle; MacCrann, Niall; Raveri, Marco; Porredon, Anna; Di Valentino, Eleonora; Muir, Jessica; Lemos, Pablo; Liddle, Andrew; Blazek, Jonathan; Campos, Andresa; Cawthon, Ross; Choi, Ami; Dodelson, Scott; Elvin-Poole, Jack; Gruen, Daniel; Ross, Ashley; Secco, Lucas F.; Sevilla, Ignacio; Sheldon, Erin; Troxel, Michael A.; Zuntz, Joe; Abbott, Tim; Aguena, Michel; Allam, Sahar; Annis, James; Avila, Santiago; Bertin, Emmanuel; Bhargava, Sunayana; Bridle, Sarah; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Costanzi, Matteo; Crocce, Martin; da Costa, Luiz; Elidaiana da Silva Pereira, Maria; Davis, Tamara; Doel, Peter; Eifler, Tim; Ferrero, Ismael; Fosalba, Pablo; Frieman, Josh; Garcia-Bellido, Juan; Gaztanaga, Enrique; Gerdes, David; Gruendl, Robert; Gschwend, Julia; Gutierrez, Gaston; Hinton, Samuel; Hollowood, Devon L.; Honscheid, Klaus; Hoyle, Ben; James, David; Jarvis, Mike; Kuehn, Kyler; Lahav, Ofer; Maia, Marcio; Marshall, Jennifer; Menanteau, Felipe; Miquel, Ramon; Morgan, Robert; Palmese, Antonella; Paz-Chinchon, Francisco; Plazas Malagón, Andrés; Roodman, Aaron; Sanchez, Eusebio; Scarpine, Vic; Schubnell, Michael; Serrano, Santiago; Smith, Mathew; Suchyta, Eric; Tarle, Gregory; Thomas, Daniel; To, Chun-Hao; Varga, Tamas Norbert; Weller, Jochen; Wilkinson, ReeseChen, Angela; Huterer, Dragan; Lee, Sujeong; Ferté, Agnès; Weaverdyck, Noah; Alonso Alves, Otavio; Leonard, C. Danielle; Maccrann, Niall; Raveri, Marco; Porredon, Anna; Di Valentino, Eleonora; Muir, Jessica; Lemos, Pablo; Liddle, Andrew; Blazek, Jonathan; Campos, Andresa; Cawthon, Ross; Choi, Ami; Dodelson, Scott; Elvin-Poole, Jack; Gruen, Daniel; Ross, Ashley; Secco, Lucas F.; Sevilla, Ignacio; Sheldon, Erin; Troxel, Michael A.; Zuntz, Joe; Abbott, Tim; Aguena, Michel; Allam, Sahar; Annis, James; Avila, Santiago; Bertin, Emmanuel; Bhargava, Sunayana; Bridle, Sarah; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Costanzi, Matteo; Crocce, Martin; da Costa, Luiz; Elidaiana da Silva Pereira, Maria; Davis, Tamara; Doel, Peter; Eifler, Tim; Ferrero, Ismael; Fosalba, Pablo; Frieman, Josh; Garcia-Bellido, Juan; Gaztanaga, Enrique; Gerdes, David; Gruendl, Robert; Gschwend, Julia; Gutierrez, Gaston; Hinton, Samuel; Hollowood, Devon L.; Honscheid, Klaus; Hoyle, Ben; James, David; Jarvis, Mike; Kuehn, Kyler; Lahav, Ofer; Maia, Marcio; Marshall, Jennifer; Menanteau, Felipe; Miquel, Ramon; Morgan, Robert; Palmese, Antonella; Paz-Chinchon, Francisco; Plazas Malagón, Andrés; Roodman, Aaron; Sanchez, Eusebio; Scarpine, Vic; Schubnell, Michael; Serrano, Santiago; Smith, Mathew; Suchyta, Eric; Tarle, Gregory; Thomas, Daniel; Chun-Hao, To; Varga, Tamas Norbert; Weller, Jochen; Wilkinson, Rees
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