27 research outputs found
Primordial non-Gaussianity with Angular correlation function: Integral constraint and validation for DES
Local primordial non-Gaussianity (PNG) is a promising observable of the
underlying physics of inflation, characterised by . We
present the methodology to measure from the Dark Energy
Survey (DES) data using the 2-point angular correlation function (ACF) with
scale-dependent bias. One of the focuses of the work is the integral
constraint. This condition appears when estimating the mean number density of
galaxies from the data and is key in obtaining unbiased
constraints. The methods are analysed for two types of simulations:
GOLIAT-PNG N-body small area simulations with equal to -100 and
100, and 1952 Gaussian ICE-COLA mocks with that follow the DES
angular and redshift distribution. We use the ensemble of GOLIAT-PNG mocks to
show the importance of the integral constraint when measuring PNG, where we
recover the fiducial values of within the when including
the integral constraint. In contrast, we found a bias of when not including it. For a DES-like scenario, we forecast a bias of
, equivalent to , when not using the IC
for a fiducial value of . We use the ICE-COLA mocks to validate
our analysis in a realistic DES-like setup finding it robust to different
analysis choices: best-fit estimator, the effect of IC, BAO damping,
covariance, and scale choices. We forecast a measurement of within
when using the DES-Y3 BAO sample, with the ACF in the
range.Comment: Version after MNRAS reviewer comments. Improved discussion in Section
7. 16 pages, 11 figure
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Recommended from our members
SPHEREx: NASA's near-infrared spectrophotometric all-sky survey
SPHEREx, the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and ices Explorer, is a NASA MIDEX mission planned for launch in 2024. SPHEREx will carry out the first all-sky spectral survey at wavelengths between 0.75”m and 5”m with spectral resolving power ~40 between 0.75 and 3.8”m and ~120 between 3.8 and 5”m At the end of its two-year mission, SPHEREx will provide 0.75-to-5”m spectra of each 6.â2 x 6.â2 pixel on the sky - 14 billion spectra in all. This paper updates an earlier description of SPHEREx presenting changes made during the mission's Preliminary Design Phase, including a discussion of instrument integration and test ow and a summary of the data processing, analysis, and distribution plans
The Vertical Structure of a Sediment-Stratified Turbolent Flow of Finite Depth
The vertical strucutre of a steady, horizontally uniform, sediment-stratified turbolent flow of finite depth is uniquely determined by four dimensionless parameters (the Rouse number, the relative friction velocity, the sediment Richardson number and the relative height), if the dependencies of the reference level and the reference suspended sediment concentration on the excess bottom shear stress are accounted for. The solution to the appropriate boundary-value problem is expected to show the property of complete similarity in the sediment Richardson number because the characteristic value of the sediment Richardson number is orders of magnitude greater than those of the other dimensionless parameters. This hypothesis is confirmed under conditions which are typical of estuaries and shallow waters by results of numerical experiments obtained using a b-L turbolence model. These results clearly demonstrate the dependence of the vertical mean velocity shear and suspended sediment concentration on the Rouse number and the relative friction velocity.JRC.(SAI)-Space Application Institut
Universal Structure of the Sediment Bottom Logarithmic Layer
Abstract not availableJRC.(IRSA)-Institute For Remote Sensing Application
A Hypothesis on Momentum and Heat Transfer near the Sea-Atmosphere Interface and a Related Simple Model
Abstract not availableNA-NOT AVAILABL
A lagrangian Model of the Phytoplankton Dynamics in the Mauritanian Upwelling Zone
Abstract not availableJRC.(IRSA)-Institute For Remote Sensing Application
Modelling the Thermal Surface Signature of Wave Breaking.
Abstract not availableJRC.(SAI)-Space Application Institut
Numerical Verification Exercises with Different Computer Models for Simulating Sea Circulation Pattern. The Vertical Diffusion of Momentum in a Forced Barotropic Sea
Abstract not availableNA-NOT AVAILABL
Universal Structure of the Sediment-Stratified Bottom Logarithmic Layer
Abstract not availableJRC.(IRSA)-Institute For Remote Sensing Application