11 research outputs found
Detecting Baryon Acoustic Oscillations in Dark Matter from Kinematic Weak Lensing Surveys
We investigate the feasibility of extracting Baryon Acoustic Oscillations
(BAO) from cosmic shear tomography. We particularly focus on the BAO scale
precision that can be achieved by future spectroscopy-based, kinematic weak
lensing (KWL) surveys \citep[e.g.,][]{Huff13} in comparison to the traditional
photometry-based weak lensing surveys. We simulate cosmic shear tomography data
of such surveys with a few simple assumptions to focus on the BAO information,
extract the spacial power spectrum, and constrain the recovered BAO feature.
Due to the small shape noise and the shape of the lensing kernel, we find that
a Dark Energy Task Force Stage IV version of such KWL survey can detect the BAO
feature in dark matter by - and measure the BAO scale at the
precision level of 4\% while it will be difficult to detect the feature in
photometry-based weak lensing surveys. With a more optimistic assumption, a
KWL-Stage IV could achieve a BAO scale measurement with
- confidence. A built-in spectroscopic galaxy survey within such
KWL survey will allow cross-correlation between galaxies and cosmic shear,
which will tighten the constraint beyond the lower limit we present in this
paper and therefore possibly allow a detection of the BAO scale bias between
galaxies and dark matter.Comment: 18 pages, 10 figures; revised arguments in section 2, results
unchange
Theoretical Systematics of Future Baryon Acoustic Oscillation Surveys
Future Baryon Acoustic Oscillation surveys aim at observing galaxy clustering
over a wide range of redshift and galaxy populations at great precision,
reaching tenths of a percent, in order to detect any deviation of dark energy
from the \LCDM model. We utilize a set of paired quasi-\Nb\, FastPM
simulations that were designed to mitigate the sample variance effect on the
BAO feature and evaluated the BAO systematics as precisely as . We
report anisotropic BAO scale shifts before and after density field
reconstruction in the presence of redshift-space distortions over a wide range
of redshift, galaxy/halo biases, and shot noise levels. We test different
reconstruction schemes and different smoothing filter scales, and introduce
physically-motivated BAO fitting models. For the first time, we derive a
Galilean-invariant infrared resummed model for halos in real and redshift
space. We test these models from the perspective of robust BAO measurements and
non-BAO information such as growth rate and nonlinear bias. We find that
pre-reconstruction BAO scale has moderate fitting-model dependence at the level
of for matter while the dependence is substantially reduced to
less than for halos. We find that post-reconstruction BAO shifts are
generally reduced to below in the presence of galaxy/halo bias and show
much smaller fitting model dependence. Different reconstruction conventions can
potentially make a much larger difference on the line-of-sight BAO scale, upto
. Meanwhile, the precision (error) of the BAO measurements is quite
consistent regardless of the choice of the fitting model or reconstruction
convention.Comment: 33 pages, 19 figures, 4 tables. Submitted to MNRAS. Matches version
accepted to MNRAS. Moderate changes were made during revision including a
comparison between TreePM and FastPM BAO featur
DESI mock challenge: constructing DESI galaxy catalogues based on FastPM simulations
Together with larger spectroscopic surveys such as the Dark Energy Spectroscopic Instrument (DESI), the precision of large scale structure studies and thus the constraints on the cosmological parameters are rapidly improving. Therefore, one must buildrealistic simulations and robust covariance matrices. We build galaxy catalogues by applying a halo occupation distribution(HOD) model upon the FASTPM simulations, such that the resulting galaxy clustering reproduces high-resolution N-bodysimulations. While the resolution and halo finder are different from the reference simulations, we reproduce the reference galaxytwo-point clustering measurements â monopole and quadrupole â to a precision required by the DESI Year 1 emission line galaxysample down to non-linear scales, i.e. k 10 Mpc hâ1. Furthermore, we compute covariance matrices basedon the resulting FASTPM galaxy clustering â monopole and quadrupole. We study for the first time the effect of fitting on Fourierconjugate (e.g. power spectrum) on the covariance matrix of the Fourier counterpart (e.g. correlation function). We estimate theuncertainties of the two parameters of a simple clustering model and observe a maximum variation of 20 per cent for the differentcovariance matrices. Nevertheless, for most studied scales the scatter is between 2 and 10 per cent. Consequently, using thecurrent pipeline we can precisely reproduce the clustering of N-body simulations and the resulting covariance matrices providerobust uncertainty estimations against HOD fitting scenarios. We expect our methodology will be useful for the coming DESIdata analyses and their extension for other studies
The DESI -body Simulation Project II: Suppressing Sample Variance with Fast Simulations
International audienceDark Energy Spectroscopic Instrument (DESI) will construct a large and precise three-dimensional map of our Universe. The survey effective volume reaches \sim20\Gpchcube. It is a great challenge to prepare high-resolution simulations with a much larger volume for validating the DESI analysis pipelines. \textsc{AbacusSummit} is a suite of high-resolution dark-matter-only simulations designed for this purpose, with 200\Gpchcube (10 times DESI volume) for the base cosmology. However, further efforts need to be done to provide a more precise analysis of the data and to cover also other cosmologies. Recently, the CARPool method was proposed to use paired accurate and approximate simulations to achieve high statistical precision with a limited number of high-resolution simulations. Relying on this technique, we propose to use fast quasi--body solvers combined with accurate simulations to produce accurate summary statistics. This enables us to obtain 100 times smaller variance than the expected DESI statistical variance at the scales we are interested in, e.g. k < 0.3\hMpc for the halo power spectrum. In addition, it can significantly suppress the sample variance of the halo bispectrum. We further generalize the method for other cosmologies with only one realization in \textsc{AbacusSummit} suite to extend the effective volume times. In summary, our proposed strategy of combining high-fidelity simulations with fast approximate gravity solvers and a series of variance suppression techniques sets the path for a robust cosmological analysis of galaxy survey data
Recommended from our members
The DESI Experiment Part II: Instrument Design
DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark
energy experiment that will study baryon acoustic oscillations and the growth
of structure through redshift-space distortions with a wide-area galaxy and
quasar redshift survey. The DESI instrument is a robotically-actuated,
fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over
a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm
spectrographs with resolution between 2000 and 5500,
depending on wavelength. The DESI instrument will be used to conduct a
five-year survey designed to cover 14,000 deg. This powerful instrument
will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak,
Arizona, along with a new optical corrector, which will provide a three-degree
diameter field of view. The DESI collaboration will also deliver a
spectroscopic pipeline and data management system to reduce and archive all
data for eventual public use
Recommended from our members
The DESI Experiment Part II: Instrument Design
DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark
energy experiment that will study baryon acoustic oscillations and the growth
of structure through redshift-space distortions with a wide-area galaxy and
quasar redshift survey. The DESI instrument is a robotically-actuated,
fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over
a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm
spectrographs with resolution between 2000 and 5500,
depending on wavelength. The DESI instrument will be used to conduct a
five-year survey designed to cover 14,000 deg. This powerful instrument
will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak,
Arizona, along with a new optical corrector, which will provide a three-degree
diameter field of view. The DESI collaboration will also deliver a
spectroscopic pipeline and data management system to reduce and archive all
data for eventual public use
Recommended from our members
The DESI Experiment Part I: Science,Targeting, and Survey Design
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark
energy experiment that will study baryon acoustic oscillations (BAO) and the
growth of structure through redshift-space distortions with a wide-area galaxy
and quasar redshift survey. To trace the underlying dark matter distribution,
spectroscopic targets will be selected in four classes from imaging data. We
will measure luminous red galaxies up to . To probe the Universe out to
even higher redshift, DESI will target bright [O II] emission line galaxies up
to . Quasars will be targeted both as direct tracers of the underlying
dark matter distribution and, at higher redshifts ( 2.1 < z < 3.5), for the
Ly- forest absorption features in their spectra, which will be used to
trace the distribution of neutral hydrogen. When moonlight prevents efficient
observations of the faint targets of the baseline survey, DESI will conduct a
magnitude-limited Bright Galaxy Survey comprising approximately 10 million
galaxies with a median . In total, more than 30 million galaxy
and quasar redshifts will be obtained to measure the BAO feature and determine
the matter power spectrum, including redshift space distortions
Overview of the DESI Legacy Imaging Surveys
The DESI Legacy Imaging Surveys (http://legacysurvey.org/) are a combination of three public projects (the Dark Energy Camera Legacy Survey, the BeijingâArizona Sky Survey, and the Mayall z-band Legacy Survey) that will jointly image â14,000 deg2 of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The combined survey footprint is split into two contiguous areas by the Galactic plane. The optical imaging is conducted using a unique strategy of dynamically adjusting the exposure times and pointing selection during observing that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering a catalog, constructed by using a probabilistic inference-based approach to estimate source shapes and brightnesses. The catalog includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12, and 22 ÎŒm) observed by the Wide-field Infrared Survey Explorer satellite during its full operational lifetime. The project plans two public data releases each year. All the software used to generate the catalogs is also released with the data. This paper provides an overview of the Legacy Surveys project
The DESI experiment part I: science, targeting, and survey design
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to . To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to . Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts (), for the Ly- forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median . In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions