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Beschreibung: In this paper we present and validate the galaxy sample used for the analysis of the Baryon Acoustic Oscillation signal (BAO) in the Dark Energy Survey (DES) Y3 data. The definition is based on a colour and redshift-dependent magnitude cut optimized to select galaxies at redshifts higher than 0.5, while ensuring a high quality determination. The sample covers ∼ 4100 square degrees to a depth of i = 22.3 (AB) at 10σ. It contains 7,031,993 galaxies in the redshift range from z= 0.6 to 1.1, with a mean effective redshift of 0.835. Redshifts are estimated with the machine learning algorithm DNF, and are validated using the VIPERS PDR2 sample. We find a mean redshift bias of zbias ∼ 0.01 and a mean uncertainty, in units of 1 + z, of σ68 ∼ 0.03. We evaluate the galaxy population of the sample, showing it is mostly built upon Elliptical to Sbc types. Furthermore, we find a low level of stellar contamination of $lesssim 4{{ m per cent}}$. We present the method used to mitigate the effect of spurious clustering coming from observing conditions and other large-scale systematics. We apply it to the BAO sampleand calculate weights that are used to get a robust estimate of the galaxy clustering signal. This paper is one of a series dedicated to the analysis of the BAO signal in DES Y3. In the companion papers we present the galaxy mock catalogues used to calibrate the analysis and the angular diameter distance constraints obtained through the fitting to the BAO scale.

Print ISSN: 0035-8711

Digitale ISSN: 1365-2966

Thema: Physik

Publiziert von Oxford University Press im Namen von The Royal Astronomical Society.

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Dark Energy Survey Year 3 Results: Deep Field optical + near-infrared images and catalogue (2021)

Hartley, W G ; Choi, A ; Amon, A ; [weitere]

Oxford University Press

In: Monthly Notices of the Royal Astronomical Society. 2021; Published 2021 Oct 27. doi: 10.1093/mnras/stab3055. [early online release]

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Publikationsdatum: 2021-10-27

Beschreibung: We describe the Dark Energy Survey (DES) Deep Fields, a set of images and associated multi-wavelength catalogue (ugrizJHKs) built from Dark Energy Camera (DECam) and Visible and Infrared Survey Telescope for Astronomy (VISTA) data. The DES Deep Fields comprise 11 fields (10 DES supernova fields plus COSMOS), with a total area of ∼30 square degrees in ugriz bands and reaching a maximum i-band depth of 26.75 (AB, 10σ, 2″). We present a catalogue for the DES 3-year cosmology analysis of those four fields with full 8-band coverage, totalling 5.88 sq. deg. after masking. Numbering 2.8million objects (1.6million post masking), our catalogue is drawn from images coadded to consistent depths of r = 25.7, i = 25, z = 24.3 mag. We use a new model-fitting code, built upon established methods, to deblend sources and ensure consistent colours across the u-band to Ks-band wavelength range. We further detail the tight control we maintain over the point-spread function modelling required for the model fitting, astrometry and consistency of photometry between the four fields. The catalogue allows us to perform a careful star-galaxy separation and produces excellent photometric redshift performance (NMAD = 0.023 at i 〈 23). The Deep-Fields catalogue will be made available as part of the cosmology data products release, following the completion of the DES 3-year weak lensing and galaxy clustering cosmology work.

Print ISSN: 0035-8711

Digitale ISSN: 1365-2966

Thema: Physik

Publiziert von Oxford University Press im Namen von The Royal Astronomical Society.

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Constraining Merging Galaxy Clusters with X-ray and Lensing Simulations & Observations: The case of Abell 2146 (2021)

Chadayammuri, Urmila ; ZuHone, John ; Nulsen, Paul ; [weitere]

Oxford University Press

In: Monthly Notices of the Royal Astronomical Society. 2021; Published 2021 Oct 30. doi: 10.1093/mnras/stab2629. [early online release]

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Publikationsdatum: 2021-10-30

Beschreibung: Galaxy cluster mergers are a powerful laboratory for testing cosmological and astrophysical models. However, interpreting individual merging clusters depends crucially on their merger configuration, defined by the masses, velocities, impact parameters, and orientation of the merger axis with respect to the plane of the sky. In this work, we investigate the impact of merger parameters on the X-ray emitting intracluster medium and gravitational lensing maps using a suite of idealised simulations of binary cluster mergers performed using the GAMER-2 code. As a test case, we focus on modeling the Bullet Cluster-like merging system Abell 2146, in which deep Chandra X-ray and lensing observations revealed prominent merger shocks as well as the mass distribution and substructures associated with this merging cluster. We identify the most interesting parameter combinations, and evaluate the effects of various parameters on the properties of merger shocks observed by deep Chandra and lensing observations. We show that due to gravitational compression of the cluster halos during the merger, previous mass estimates from weak lensing are too high. The plane of the merger is tilted further from the plane of the sky than estimated previously, up to 30○ from the plane of the sky. We discuss the applicability of our results to multi-wavelength observations of merging galaxy clusters and their use as probes of cosmology and plasma physics.

Print ISSN: 0035-8711

Digitale ISSN: 1365-2966

Thema: Physik

Publiziert von Oxford University Press im Namen von The Royal Astronomical Society.

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