Top PDF Dark Energy Survey Year 1 results: Cosmological constraints from cosmic shear

Dark Energy Survey Year 1 results: Cosmological constraints from cosmic shear

Dark Energy Survey Year 1 results: Cosmological constraints from cosmic shear

For both catalogs, we use only objects that pass the default recommended selection FLAGS_SELECT (see selection criteria defined in [40] ). We additionally limit objects to have photo- z point estimates within the redshift range 0.2 –1.3 (cf. Sec. II B ) and to fall within the large, contiguous southern portion of the footprint (dec < −35) that overlaps with the SPT survey. Finally, we limit our study to objects that are contained within the RED M A G I C mask described in [55] , which additionally removes a few tens of deg 2 from the original shape catalog footprint, bringing its final effective area to 1321 deg 2 . This final mask, while not strictly necessary for cosmic shear, is applied to make this work consistently with the joint cosmological constraints combin- ing weak lensing and galaxy clustering in [53] , where the same footprint is assumed in our covariance calculation. This has the added benefit of reducing depth variation across the field, and thus spatial variations in our redshift distribution. We derive the measurement noise σ 2 m;i for
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Dark Energy Survey Year 1 results: cosmological constraints from cosmic shear

Dark Energy Survey Year 1 results: cosmological constraints from cosmic shear

For both catalogs, we use only objects that pass the default recommended selection FLAGS_SELECT (see selection criteria defined in [40] ). We additionally limit objects to have photo- z point estimates within the redshift range 0.2 –1.3 (cf. Sec. II B ) and to fall within the large, contiguous southern portion of the footprint (dec < −35) that overlaps with the SPT survey. Finally, we limit our study to objects that are contained within the RED M A G I C mask described in [55] , which additionally removes a few tens of deg 2 from the original shape catalog footprint, bringing its final effective area to 1321 deg 2 . This final mask, while not strictly necessary for cosmic shear, is applied to make this work consistently with the joint cosmological constraints combin- ing weak lensing and galaxy clustering in [53] , where the same footprint is assumed in our covariance calculation. This has the added benefit of reducing depth variation across the field, and thus spatial variations in our redshift distribution. We derive the measurement noise σ 2 m;i for
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Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

The shape distortions produced by gravitational lensing, while cosmologically informative, are extremely difficult to measure, since the induced source galaxy ellipticities are at the percent level, and a number of systematic effects can ob- scure the signal. Indeed, the first detections of weak lens- ing were made by cross-correlating observed shapes of source galaxies with massive foreground lenses [21, 22]. A wa- tershed moment came in the year 2000 when four research groups nearly simultaneously announced the first detections of cosmic shear [23–26]. While these and subsequent weak lensing measurements are also consistent with ΛCDM, only recently have they begun to provide competitive constraints on cosmological parameters [27–36]. Galaxy–galaxy lensing measurements have also matured to the point where their com- bination with galaxy clustering breaks degeneracies between the cosmological parameters and bias, thereby helping to con- strain dark energy [22, 37–48]. The combination of galaxy clustering, cosmic shear, and galaxy–galaxy lensing measure- ments powerfully constrains structure formation in the late universe. As for cosmological analyses of samples of galaxy clusters [see 49, for a review], redshift space distortions in the clustering of galaxies [50, and references therein] and other measurements of late-time structure, a primary test is whether these are consistent, in the framework of ΛCDM, with mea- surements from cosmic microwave background (CMB) exper- iments that are chiefly sensitive to early-universe physics [51– 54] as well as lensing of its photons by the large-scale struc- tures [e.g. 55–57].
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Accounting for baryons in cosmological constraints from cosmic shear

Accounting for baryons in cosmological constraints from cosmic shear

processes directly, so baryonic simulations rely on a variety of effective models for these processes. Effective models for baryonic processes remain quite uncertain, and it is not possible to produce a definitive prediction for the influences of baryonic processes on observables, such as convergence power spectra. The utility of a simulation suite such as OWLS is that it provides a range of distinct, but plausible, predictions for observables so that system- atic errors induced by our ignorance of baryonic physics can be estimated. An important advantage of the test that we present here is that we are applying a mitigation strat- egy developed on the simulations of Rudd et al. [18] to an independent set of simulations that were performed using markedly different simulation strategies. The details of the OWLS simulations have been given in Refs. [26,42–46], while the OWLS power spectra were the subject of Ref. [27], to which we refer the reader as these details are not of immediate importance in the present paper. Follow-up studies by McCarthy et al. [47] and McCarthy et al. [48] suggest that the properties of galaxies and hot gas in galaxy groups are modeled most reliably in the ‘‘AGN’’ simulation, which includes strong feedback from active galactic nuclei.
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Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Figure 14 shows the results in the extended wCDM param- eter space using Planck alone, and DES alone, combined, and with the addition of BAO+SNe. As discussed in [51], the con- straints on the dark energy equation of state from Planck alone are misleading. They stem from the measurement of the dis- tance to the last scattering surface, and that distance (in a flat universe) depends upon the Hubble constant as well, so there is a strong w − h degeneracy. The low values of w seen in Figure 14 from Planck alone correspond to very large values of h, ruled out by local distance indicators. Since DES is not sensitive to the Hubble constant, it does not break this degen- eracy. Additionally, the Bayes factor in Eq. (VI.4) that quan- tifies whether adding the extra parameter w is warranted is R w = 0.018. Therefore, opening up the dark energy equation of state is not favored on a formal level for the DES+Planck combination. Finally, the Bayes factor for combining DES and Planck (no lensing) in wCDM is equal to 0.18, which we identified earlier as “substantial” evidence in favor of the hypothesis that these two data sets are not consistent in the context of this model. These factors degrade the legitimacy of the value w = −1.34 +0.08 −0.15 returned by the DES+Planck combination.
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Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing

Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana- Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo `a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Minist´erio da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energ´eticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ci`encies de l ’Espai, the Institut de Física d’Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. This work was based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under Grants No. AST-1138766 and No. AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under Grants No. AYA2015-71825, No. ESP2015-88861, No. FPA2015-68048, No. SEV-2012-0234, No. SEV- 2016-0597, and No. MDM-2015-0509, some of which include European Research Development Fund (ERDF) funds from the European Union. I. F. A. E. is partially funded by the Centres de Recerce de Catalunya (CERCA) program of the Generalitat de Catalunya. Research leading to these results has received funding from the European
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Dark Energy Survey Year 1 results: The impact of galaxy neighbours on weak lensing cosmology with IM3SHAPE

Dark Energy Survey Year 1 results: The impact of galaxy neighbours on weak lensing cosmology with IM3SHAPE

1 I N T R O D U C T I O N A standard and well-tested prediction of general relativity is that a concentration of mass will distort the spacetime around it, and thus produce a curious phenomenon called gravitational lensing. The most obvious manifestation is about massive galaxy clusters, where background galaxies can be elongated into crescent-shaped arcs. So-called strong lensing of galaxies was first observed in the late 1980s and has been confirmed many times since. A subtler, but from a cosmologist’s perspective more powerful, consequence of gravitational lensing is that background fluctuations in the density of dark matter will induce coherent distortions to photons’ paths. This effect is known as cosmic shear, and it was first detected by four groups at around the same time close to two decades ago (Bacon, Refregier & Ellis 2000 ; Kaiser, Wilson & Luppino 2000 ; Van Waerbeke et al. 2000 ; Wittman et al. 2000 ). Cosmic shear has the potential to be the single most powerful probe in the toolbox of modern cosmology. The spatial correlations due to lensing are a direct imprint of the large-scale mass distribution of the Uni- verse. Thus it allows one to study the total mass of the Universe and the growth of structure within it (Maoli et al. 2001 ; Jarvis et al. 2006 ; Massey et al. 2007b ; Heymans et al. 2013 ; Kilbinger et al. 2013 ; Dark Energy Survey Collaboration 2016 ; Jee et al.
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Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

4 VA L I DAT I N G T H E R E D S H I F T D I S T R I B U T I O N U S I N G C O S M O S M U LT I B A N D P H OT O M E T RY In Bonnett et al. ( 2016 ), we made use of COSMOS photometric redshifts as an independent estimate and validation of the redshift distribution of the WL source galaxies. We made cuts in magnitude, full width at half-maximum, and surface brightness to the source catalogue from DECam images in the COSMOS field that were depth-matched to the main survey area. These cuts approximated the selection function of the shape catalogues used for the cosmic shear analysis. Similar techniques that find COSMOS samples of galaxies matched to a lensing source catalogue by a combination of magnitude, colour, and morphological properties have been applied by numerous studies (Applegate et al. 2014 ; Hoekstra et al. 2015 ; Okabe & Smith 2016 ; Cibirka et al. 2017 ; Amon et al. 2018 ). In this work, we modify the approach to reduce statistical and systematic uncertainty on its estimate of mean redshift and carefully estimate the most significant sources of systematic error.
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Dark Energy Survey Year 1 results: the impact of galaxy neighbours on weak lensing cosmology with IM3SHAPE

Dark Energy Survey Year 1 results: the impact of galaxy neighbours on weak lensing cosmology with IM3SHAPE

1 I N T R O D U C T I O N A standard and well-tested prediction of general relativity is that a concentration of mass will distort the spacetime around it, and thus produce a curious phenomenon called gravitational lensing. The most obvious manifestation is about massive galaxy clusters, where background galaxies can be elongated into crescent-shaped arcs. So-called strong lensing of galaxies was first observed in the late 1980s and has been confirmed many times since. A subtler, but from a cosmologist’s perspective more powerful, consequence of gravitational lensing is that background fluctuations in the density of dark matter will induce coherent distortions to photons’ paths. This effect is known as cosmic shear, and it was first detected by four groups at around the same time close to two decades ago (Bacon, Refregier & Ellis 2000 ; Kaiser, Wilson & Luppino 2000 ; Van Waerbeke et al. 2000 ; Wittman et al. 2000 ). Cosmic shear has the potential to be the single most powerful probe in the toolbox of modern cosmology. The spatial correlations due to lensing are a direct imprint of the large-scale mass distribution of the Uni- verse. Thus it allows one to study the total mass of the Universe and the growth of structure within it (Maoli et al. 2001 ; Jarvis et al. 2006 ; Massey et al. 2007b ; Heymans et al. 2013 ; Kilbinger et al. 2013 ; Dark Energy Survey Collaboration 2016 ; Jee et al.
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Dark Energy Survey Year 1 results: cross-correlation redshifts – methods and systematics characterization

Dark Energy Survey Year 1 results: cross-correlation redshifts – methods and systematics characterization

our calibration procedure, as a function of WL source red- shift bin and photo-z code, are provided in § 4.5 , and stand at the level of ∆hzi . 0.02. We further address the impact of changing our fiducial choices concerning the angular scales and method used for the clustering-based estimate, and discuss how our method- ology could be improved. In particular, future works have to efficiently deal with the problem of the redshift evolution of the galaxy–matter bias of the science sample. This could be achieved by further splitting the science sample in lumi- nosity/color cells. Other probes, like galaxy-galaxy lensing, could be also used to break the degeneracy between galaxy bias and redshift distribution. Lensing magnification, whose impact is marginal in this study, might no longer be negli- gible as survey requirements become more stringent. Lastly, we note that as clustering-based methods improve and sys- tematic errors become sub-dominant with respect to statis- tical errors, full modeling of the cross-covariance between clustering-based n(z) and other 2-point correlation functions will be required so as not to bias the cosmological analysis. The calibration strategy presented in this paper is fully implemented in the DES Y1 cosmic shear and combined two-point function analysis ( Troxel et al. 2017 ; DES Col- laboration 2017 ). Its direct application to DES Y1 data is discussed in two other companion papers ( Davis et al. 2017b ;
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Dark Energy Survey Year 1 results: curved-sky weak lensing mass map

Dark Energy Survey Year 1 results: curved-sky weak lensing mass map

few advances over the SV studies were made: first, given the large area of the mass map on the sky, it was necessary to go beyond the flat-sky approximation and employ curved-sky estimators. The im- plementation of the curved-sky reconstruction borrows from tools developed for CMB polarization analyses and has been studied in detail in the context of weak lensing mass mapping and cosmic shear (Heavens 2003; Castro, Heavens & Kitching 2005; Heavens, Kitching & Taylor 2006; Kitching et al. 2014; Leistedt et al. 2017; Wallis et al. 2017). The first all-sky curved weak lensing maps con- structed from simulations were presented in Fosalba et al. (2008), which was an extension from the work on constructing mock galaxy catalogues in Gaztanaga & Bernardeau (1998). Second, we move from a single redshift bin to multiple redshift bins, a first step to- wards constructing a 3D weak lensing map. These tomographic bins match those used in the DES Y1 cosmology analysis, thus making our maps very complementary to the series of DES Y1 pa- pers that focus on two-point statistics (DES Collaboration 2017; MacCrann et al., in preparation; Prat et al. 2017; Troxel et al. 2017). Specifically, this paper presents the spatial configuration and phase information of the data that goes into these cosmolog- ical analyses. Finally, we explore for the first time the possibility
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Dark Energy Survey year 1 results: redshift distributions of the weak-lensing source galaxies

Dark Energy Survey year 1 results: redshift distributions of the weak-lensing source galaxies

In Bonnett et al. ( 2016 ), we made use of COSMOS photometric redshifts as an independent estimate and validation of the redshift distribution of the WL source galaxies. We made cuts in magnitude, full width at half-maximum, and surface brightness to the source catalogue from DECam images in the COSMOS field that were depth-matched to the main survey area. These cuts approximated the selection function of the shape catalogues used for the cosmic shear analysis. Similar techniques that find COSMOS samples of galaxies matched to a lensing source catalogue by a combination of magnitude, colour, and morphological properties have been applied by numerous studies (Applegate et al. 2014 ; Hoekstra et al. 2015 ; Okabe & Smith 2016 ; Cibirka et al. 2017 ; Amon et al. 2018 ). In this work, we modify the approach to reduce statistical and systematic uncertainty on its estimate of mean redshift and carefully estimate the most significant sources of systematic error.
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Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

In Bonnett et al. ( 2016 ) we made use of COSMOS photo- metric redshifts as an independent estimate and validation of the redshift distribution of the weak lensing source galaxies. We made cuts in magnitude, FWHM and surface brightness to the source catalogue from DECam images in the COS- MOS field that were depth-matched to the main survey area. These cuts approximated the selection function of the shape catalogues used for the cosmic shear analysis. Similar tech- niques that find COSMOS samples of galaxies matched to a lensing source catalog by a combination of magnitude, color and morphological properties have been applied by numer- ous studies ( Applegate et al. 2014 ; Hoekstra et al. 2015 ; Ok- abe & Smith 2016 ; Cibirka et al. 2017 ; Amon et al. 2017 ). In the present work, we modify the approach to reduce sta- tistical and systematic uncertainty on its estimate of mean redshift and carefully estimate the most significant sources of systematic error.
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Dark Energy Survey Year 1 Results: Weak Lensing Shape Catalogues

Dark Energy Survey Year 1 Results: Weak Lensing Shape Catalogues

8 SUMMARY AND DISCUSSION We have presented two independent catalogues of shape measure- ments of galaxies imaged in Year One of the Dark Energy Sur- vey, covering 1500 square degrees of the Southern sky and con- taining 34.8 million (for METACALIBRATION ) and 21.9 million (for IM 3 SHAPE ) objects. They have passed a battery of tests that demonstrate that, when appropriately used with calibration and er- ror models, they are suitable for weak lensing science. In compan- ion papers we also demonstrate that these catalogues lead to con- sistent cosmological constraints: in Troxel et al. ( 2017 ) we study constraints from cosmic shear, in Prat et al. ( 2017 ) we examine galaxy-galaxy lensing, and in DES Collaboration et al. ( 2017 ) we study both in conjunction with galaxy density correlation functions. This work is the first application of the metacalibration method to real data, and demonstrates its significant power in the face of noise and model biases, and especially for its approach to dealing with the pernicious issue of selection biases. This work also makes use of the most sophisticated image simulations currently used for lensing noise and model bias calibration, which account for a wide range of systematic effects that would otherwise produce a significantly biased IM 3 SHAPE catalogue. We emphasize the im- portance of carefully ensuring that simulations match the data in as many ways as possible, including PSF patterns, masks, weights, and processing selections.
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Dark Energy Survey year 1 results: Galaxy-galaxy lensing

Dark Energy Survey year 1 results: Galaxy-galaxy lensing

We present galaxy-galaxy lensing measurements from 1321 sq. deg. of the Dark Energy Survey (DES) Year 1 (Y1) data. The lens sample consists of a selection of 660,000 red galaxies with high- precision photometric redshifts, known as redMaGiC, split into five tomographic bins in the redshift range 0.15 < z < 0.9. We use two different source samples, obtained from the Metacalibration (26 million galaxies) and im3shape (18 million galaxies) shear estimation codes, which are split into four photometric redshift bins in the range 0.2 < z < 1.3. We perform extensive testing of potential systematic effects that can bias the galaxy-galaxy lensing signal, including those from shear estimation, photometric redshifts, and observational properties. Covariances are obtained from jackknife subsamples of the data and validated with a suite of log-normal simulations. We use the shear-ratio geometric test to obtain independent constraints on the mean of the source redshift distributions, providing validation of those obtained from other photo-z studies with the same data. We find consistency between the galaxy bias estimates obtained from our galaxy-galaxy lensing measurements and from galaxy clustering, therefore showing the galaxy-matter cross-correlation coefficient r to be consistent with one, measured over the scales used for the cosmological analysis. The results in this work present one of the three two-point correlation functions, along with galaxy clustering and cosmic shear, used in the DES cosmological analysis of Y1 data, and hence the methodology and the systematics tests presented here provide a critical input for that study as well as for future cosmological analyses in DES and other photometric galaxy surveys.
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Dark Energy Survey Year 1 Results: Cross-correlation between Dark Energy Survey Y1 galaxy weak lensing and South Pole Telescope+Planck CMB weak lensing

Dark Energy Survey Year 1 Results: Cross-correlation between Dark Energy Survey Y1 galaxy weak lensing and South Pole Telescope+Planck CMB weak lensing

−0.28 . The data do not constrain m 1 well (i.e., the constraint is prior dominated), which could be explained by the small overlap between the CMB lensing and the galaxy lensing kernel for this bin. These results are consistent with the constraints from cosmic shear measurements when the parameters are marginalized over in the same way: m 1;2;3;4 ¼½0.02 þ0.15 −0.16 ;−0.04 þ0.09 −0.10 ;−0.10 þ0.05 −0.05 ;−0.05 þ0.06 −0.06 , but significantly weaker than the imposed priors in [12] , which point to best-fit values of 0.012 þ0.023 −0.023 for all the bins. These results are summarized in Table III , and the posterior distributions are shown in Fig. 5 . Our analysis demonstrates the potential of using cross-correlation measurements between galaxy lensing and CMB lensing to constrain shear calibration bias. However, to reach the level of DES priors, the signal to noise of the galaxy-CMB lensing cross correlations would have to improve by a factor of approximately 30.
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First cosmological results using Type Ia supernovae from the Dark Energy Survey: measurement of the Hubble constant

First cosmological results using Type Ia supernovae from the Dark Energy Survey: measurement of the Hubble constant

Figure 1. Here we illustrate the inverse distance ladder method. The white data points are the BAO distance measurements, and the black data points are the SNe Ia data. The DES-SN3YR sample comprises the higher redshift DES SNe (illustrated with hexagonal points), and the Low-z SNe (illustrated with triangular points). The red line shows our best-fitting cosmographical model, and the shaded region is the 68 per cent confidence region. The blue dashed line and shaded region illustrates the equivalent constraints from just the BAO data, without any supernovae. The blue, BAO-only region is very large at z > 0.7 because we fit only for r s , and not the absolute distance scale at the CMB.
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Measuring Cosmic Acceleration And Constraining Dark Energy Models With Transients Discovered In The Dark Energy Survey

Measuring Cosmic Acceleration And Constraining Dark Energy Models With Transients Discovered In The Dark Energy Survey

SN Ia cosmological constraints rely on the ability to internally transform each SN flux mea- surement in ADU (Analog/Digital Units) into a ‘top-of-the-galaxy’ brightness. This is done in two steps, first via measurements of Hubble Space Telescope (HST) CalSpec 1 standard stars to obtain a top-of-the-atmosphere brightness, which is discussed here. Second, we ob- tain top-of-the-galaxy brightness by accounting for the Milky Way extinction along the line of sight, values for which are obtained from Schlegel et al. (1998) & Schlafly & Finkbeiner (2011a). Measurements of cosmological parameters using SNe Ia are sensitive to filter cali- bration uncertainties (internal) due to the fact that at higher redshift, constraints of the SN light curve models rely on observed fluxes in a different set of filters than at lower redshift. A dependence in SN cosmological distances as a function of redshift could arise from differ- ences in the calibration between the low-z and DES subsets (external). Below we discuss the steps taken to both internally and externally calibrate the DES-SN measurements.
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Dark Energy Survey year 1 results: constraints on extended cosmological models from galaxy clustering and weak lensing

Dark Energy Survey year 1 results: constraints on extended cosmological models from galaxy clustering and weak lensing

Dark matter and dark energy leave numerous unambigu- ous imprints in the expansion rate of the universe and in the rate of growth of cosmic structures as a function of time. The theoretical modeling and direct measurements of these signatures have led to a renaissance in data-driven cosmol- ogy. Numerous ground- and space-based sky surveys have dramatically improved our census of dark matter and dark energy over the past two decades, and have led to a consensus model with ∼5% energy density in baryons, ∼25% in cold (nonrelativistic) dark matter (CDM), and ∼70% in dark energy. These probes, reviewed in [4 –6] , include the cosmic microwave background (CMB; [7] ); galaxy clustering including the location of the baryon acoustic oscillation (BAO) feature and the impact of redshift space distortions (RSD); distances to type Ia supernovae (SNe Ia); weak gravitational lensing (WL [8] ), given by tiny distortions in the shapes of galaxies due to the deflection of light by intervening large-scale structure; and the abundance of clusters of galaxies [9] .
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Dark Energy Survey Year-1 results: galaxy mock catalogues for BAO

Dark Energy Survey Year-1 results: galaxy mock catalogues for BAO

In order to analyse the data, we need an adequate theoretical framework. Even though there are analytic models that can help us understand the structure formation of the Universe (Zel’dovich 1970 ; Press & Schechter 1974 ; Kaiser 1984 , 1987 ; Bond et al. 1991 ; Moutarde et al. 1991 ; Cooray & Sheth 2002 ), most realistic models are based on numerical simulations. Simulations have the additional advantages that they allow us to easily include observational effects such as masks and redshift uncertainties and can realistically mimic how these couple with other sources of uncertainty such as cosmic variance or shot noise. For the estimation of the covariance matrices of our measurements, we need a number of the order of hundreds to thousands of simulations, depending on the size of the data vector analysed (Dodelson & Schneider 2013 ), in order that the uncertainty in the covariance matrices is subdominant for the final results. As full N-Body simulations require considerable computing resources, running that number of N-Body simulations is unfeasible. Approx- imate mock catalogues are an alternative to simulate our data set in a much more computationally efficient way (Coles & Jones 1991 ; Bond & Myers 1996 ; Scoccimarro & Sheth 2002 ; Manera et al. 2013 ; Monaco et al. 2013 ; Tassev, Zaldarriaga & Eisenstein 2013 ; White, Tinker & McBride 2014; Avila et al. 2015; Chuang et al. 2015a,b ; Kitaura et al. 2016 ; Monaco 2016 ). These methods are limited in accuracy at small scales, however, these methods have
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