1,860 research outputs found
Halo Occupation Distribution of Emission Line Galaxies: fitting method with Gaussian Processes
The halo occupation distribution (HOD) framework is an empirical method to
describe the connection between dark matter halos and galaxies, which is
constrained by small scale clustering data. Efficient fitting procedures are
required to scan the HOD parameter space. This paper describes such a method
based on Gaussian Processes to iteratively build a surrogate model of the
posterior of the likelihood surface from a reasonable amount of likelihood
computations, typically two orders of magnitude less than standard Monte Carlo
Markov chain algorithms. Errors in the likelihood computation due to stochastic
HOD modelling are also accounted for in the method we propose. We report
results of reproducibility, accuracy and stability tests of the method derived
from simulation, taking as a test case star-forming emission line galaxies,
which constitute the main tracer of the Dark Energy Spectroscopic Instrument
and have so far a poorly constrained galaxy-halo connection from observational
data
Constraining CDM with density-split clustering
The dependence of galaxy clustering on local density provides an effective
method for extracting non-Gaussian information from galaxy surveys. The
two-point correlation function (2PCF) provides a complete statistical
description of a Gaussian density field. However, the late-time density field
becomes non-Gaussian due to non-linear gravitational evolution and higher-order
summary statistics are required to capture all of its cosmological information.
Using a Fisher formalism based on halo catalogues from the Quijote simulations,
we explore the possibility of retrieving this information using the
density-split clustering (DS) method, which combines clustering statistics from
regions of different environmental density. We show that DS provides more
precise constraints on the parameters of the CDM model compared to
the 2PCF, and we provide suggestions for where the extra information may come
from. DS improves the constraints on the sum of neutrino masses by a factor of
and by factors of 5, 3, 4, 6, and 6 for , , , ,
and , respectively. We compare DS statistics when the local density
environment is estimated from the real or redshift-space positions of haloes.
The inclusion of DS autocorrelation functions, in addition to the
cross-correlation functions between DS environments and haloes, recovers most
of the information that is lost when using the redshift-space halo positions to
estimate the environment. We discuss the possibility of constructing
simulation-based methods to model DS clustering statistics in different
scenarios.Comment: Submitted to MNRAS. Source code for all figures in the paper is
provided in the caption
Combined full shape analysis of BOSS galaxies and eBOSS quasars using an iterative emulator
Standard full-shape clustering analyses in Fourier space rely on a fixed
power spectrum template, defined at the fiducial cosmology used to convert
redshifts into distances, and compress the cosmological information into the
Alcock-Paczynski parameters and the linear growth rate of structure. In this
paper, we propose an analysis method that operates directly in the cosmology
parameter space and varies the power spectrum template accordingly at each
tested point. Predictions for the power spectrum multipoles from the TNS model
are computed at different cosmologies in the framework of .
Applied to the final eBOSS QSO and LRG samples together with the low-z DR12
BOSS galaxy sample, our analysis results in a set of constraints on the
cosmological parameters , , ,
and . To reduce the number of computed models, we construct an iterative
process to sample the likelihood surface, where each iteration consists of a
Gaussian process regression. This method is validated with mocks from N-body
simulations. From the combined analysis of the (e)BOSS data, we obtain the
following constraints: and without any external prior. The eBOSS quasar sample
alone shows a discrepancy compared to the Planck prediction.Comment: 13 pages, 7 figure
Angular clustering properties of the DESI QSO target selection using DR9 Legacy Imaging Surveys
The quasar target selection for the upcoming survey of the Dark Energy Spectroscopic Instrument (DESI) will be fixed for the next 5 yr. The aim of this work is to validate the quasar selection by studying the impact of imaging systematics as well as stellar and galactic contaminants, and to develop a procedure to mitigate them. Density fluctuations of quasar targets are found to be related to photometric properties such as seeing and depth of the Data Release 9 of the DESI Legacy Imaging Surveys. To model this complex relation, we explore machine learning algorithms (random forest and multilayer perceptron) as an alternative to the standard linear regression. Splitting the footprint of the Legacy Imaging Surveys into three regions according to photometric properties, we perform an independent analysis in each region, validating our method using extended Baryon Oscillation Spectroscopic Survey (eBOSS) EZ-mocks. The mitigation procedure is tested by comparing the angular correlation of the corrected target selection on each photometric region to the angular correlation function obtained using quasars from the Sloan Digital Sky Survey (SDSS) Data Release 16. With our procedure, we recover a similar level of correlation between DESI quasar targets and SDSS quasars in two-thirds of the total footprint and we show that the excess of correlation in the remaining area is due to a stellar contamination that should be removed with DESI spectroscopic data. We derive the Limber parameters in our three imaging regions and compare them to previous measurements from SDSS and the 2dF QSO Redshift Survey.This research is supported by the Director, Office of Science, Office of High Energy Physics of the U.S. Department of Energy under contract no. DE-AC02-05CH11231, and by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract; additional support for DESI is provided by the U.S. National Science Foundation, Division of Astronomical Sciences under contract no. AST-0950945 to the NSFâs National OpticalâInfrared Astronomy Research Laboratory; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology, Mexico; the Ministry of Economy of Spain, and by the DESI Member Institutions.
ADM was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Number DE-SC0019022
The Completed SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Growth rate of structure measurement from cosmic voids
We present a void clustering analysis in configuration-space using the
completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation
Spectroscopic Survey (eBOSS) DR16 samples. These samples consist of Luminous
Red Galaxies (LRG) combined with the high redshift tail of the SDSS-III Baryon
Oscillation Spectroscopic Survey (BOSS) DR12 CMASS galaxies (called as
LRG+CMASS sample), Emission Line Galaxies (ELG) and quasars (QSO). We build
void catalogues from the three eBOSS DR16 samples using a ZOBOV-based
algorithm, providing 2,814 voids, 1,801 voids and 4,347 voids in the LRG+CMASS,
ELG and QSO samples, respectively, spanning the redshift range . We
measure the redshift space distortions (RSD) around voids using the anisotropic
void-galaxy cross-correlation function and we extract the distortion parameter
. We test the methodology on realistic simulations before applying it to
the data, and we investigate all our systematic errors on these mocks. We find
, and , for
the LRG+CMASS, ELG and QSO sample, respectively. The quoted errors include
systematic and statistical contributions. In order to convert our measurements
in terms of the growth rate , we use consensus values of linear bias
from the eBOSS DR16 companion papers~\citep{eBOSScosmo}, resulting in the
following constraints: ,
and . Our
measurements are consistent with other measurements from eBOSS DR16 using
conventional clustering techniques.Comment: 17 pages, 8 figure
Efficient CRISPR/Cas9-mediated editing of trinucleotide repeat expansion in myotonic dystrophy patient-derived iPS and myogenic cells
International audienceCRISPR/Cas9 is an attractive platform to potentially correct dominant genetic diseases by gene editing with unprecedented precision. In the current proof-of-principle study, we explored the use of CRISPR/Cas9 for gene-editing in myotonic dys-trophy type-1 (DM1), an autosomal-dominant muscle disorder, by excising the CTG-repeat expansion in the 3-untranslated-region (UTR) of the human myotonic dystrophy protein kinase (DMPK) gene in DM1 patient-specific induced pluripotent stem cells (DM1-iPSC), DM1-iPSC-derived myogenic cells and DM1 patient-specific myoblasts. To eliminate the pathogenic gain-of-function mutant DMPK transcript , we designed a dual guide RNA based strategy that excises the CTG-repeat expansion with high efficiency , as confirmed by Southern blot and single molecule real-time (SMRT) sequencing. Correction efficiencies up to 90% could be attained in DM1-iPSC as confirmed at the clonal level, following ribonucle-oprotein (RNP) transfection of CRISPR/Cas9 components without the need for selective enrichment. Expanded CTG repeat excision resulted in the disappearance of ribonuclear foci, a quintessential cellular phenotype of DM1, in the corrected DM1-iPSC, DM1-iPSC-derived myogenic cells and DM1 myoblasts. Consequently, the normal intracellular localization of the muscleblind-like splicing regulator 1 (MBNL1) was restored, resulting in the normalization of splicing pattern of SERCA1. This study validates the use of CRISPR/Cas9 for gene editing of repeat expansions
The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey : pairwise-inverse probability and angular correction for fibre collisions in clustering measurements
HJS is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0014329. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. This project has received funding from the European Research Council (ERC) under the European Unionâs Horizon 2020 research and innovation programme (grant agreement No 693024).The completed extended Baryon Oscillation Spectroscopic Survey (eBOSS) catalogues contain redshifts of 344â080 quasars at 0.8 < z < 2.2, 174â816 luminous red galaxies between 0.6 < z < 1.0, and 173â736 emission-line galaxies over 0.6 < z < 1.1 in order to constrain the expansion history of the Universe and the growth rate of structure through clustering measurements. Mechanical limitations of the fibre-fed spectrograph on the Sloan telescope prevent two fibres being placed closer than 62 arcsec in a single pass of the instrument. These âfibre collisionsâ strongly correlate with the intrinsic clustering of targets and can bias measurements of the two-point correlation function resulting in a systematic error on the inferred values of the cosmological parameters. We combine the new techniques of pairwise-inverse probability and the angular upweighting (PIP+ANG) to correct the clustering measurements for the effect of fibre collisions. Using mock catalogues, we show that our corrections provide unbiased measurements, within data precision, of both the projected wp(rp) and the redshift-space multipole Ο(â = 0, 2, 4)(s) correlation functions down to 0.1hâ1Mpcâ , regardless of the tracer type. We apply the corrections to the eBOSS DR16 catalogues. We find that, on scales sâł20hâ1Mpcsâł20hâ1Mpc for Οâ, as used to make baryon acoustic oscillation and large-scale redshift-space distortion measurements, approximate methods such as nearest-neighbour upweighting are sufficiently accurate given the statistical errors of the data. Using the PIP method, for the first time for a spectroscopic program of the Sloan Digital Sky Survey, we are able to successfully access the one-halo term in the clustering measurements down to âŒ0.1hâ1Mpc scales. Our results will therefore allow studies that use the small-scale clustering to strengthen the constraints on both cosmological parameters and the halo occupation distribution models.Publisher PDFPeer reviewe
The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: exploring the Halo Occupation Distribution model for Emission Line Galaxies
We study the modelling of the Halo Occupation Distribution (HOD) for the
eBOSS DR16 Emission Line Galaxies (ELGs). Motivated by previous theoretical and
observational studies, we consider different physical effects that can change
how ELGs populate haloes. We explore the shape of the average HOD, the fraction
of satellite galaxies, their probability distribution function (PDF), and their
density and velocity profiles. Our baseline HOD shape was fitted to a
semi-analytical model of galaxy formation and evolution, with a decaying
occupation of central ELGs at high halo masses. We consider Poisson and
sub/super-Poissonian PDFs for satellite assignment. We model both NFW and
particle profiles for satellite positions, also allowing for decreased
concentrations. We model velocities with the virial theorem and particle
velocity distributions. Additionally, we introduce a velocity bias and a net
infall velocity. We study how these choices impact the clustering statistics
while keeping the number density and bias fixed to that from eBOSS ELGs. The
projected correlation function, , captures most of the effects from the
PDF and satellites profile. The quadrupole, , captures most of the
effects coming from the velocity profile. We find that the impact of the mean
HOD shape is subdominant relative to the rest of choices. We fit the clustering
of the eBOSS DR16 ELG data under different combinations of the above
assumptions. The catalogues presented here have been analysed in companion
papers, showing that eBOSS RSD+BAO measurements are insensitive to the details
of galaxy physics considered here. These catalogues are made publicly
available.Comment: Data available here: http://popia.ft.uam.es/eBOSS_ELG_OR_mocks. A
description of eBOSS and links to all associated publications can be found
here: https://www.sdss.org/surveys/eboss/ ; 24 pages, 17 Figures; Published
in MNRAS 25 Sep 202
Local primordial non-Gaussianity from the large-scale clustering of photometric DESI luminous red galaxies
We use angular clustering of luminous red galaxies from the Dark Energy
Spectroscopic Instrument (DESI) imaging surveys to constrain the local
primordial non-Gaussianity parameter fNL. Our sample comprises over 12 million
targets, covering 14,000 square degrees of the sky, with redshifts in the range
0.2< z < 1.35. We identify Galactic extinction, survey depth, and astronomical
seeing as the primary sources of systematic error, and employ linear regression
and artificial neural networks to alleviate non-cosmological excess clustering
on large scales. Our methods are tested against log-normal simulations with and
without fNL and systematics, showing superior performance of the neural network
treatment in reducing remaining systematics. Assuming the universality
relation, we find fNL at 68\%(95\%) confidence.
With a more aggressive treatment, including regression against the full set of
imaging maps, our maximum likelihood value shifts slightly to fNL and
the uncertainty on fNL increases due to the removal of large-scale clustering
information. We apply a series of robustness tests (e.g., cuts on imaging,
declination, or scales used) that show consistency in the obtained constraints.
Despite extensive efforts to mitigate systematics, our measurements indicate
fNL > 0 with a 99.9 percent confidence level. This outcome raises concerns as
it could be attributed to unforeseen systematics, including calibration errors
or uncertainties associated with low-\ell systematics in the extinction
template. Alternatively, it could suggest a scale-dependent fNL model--causing
significant non-Gaussianity around large-scale structure while leaving cosmic
microwave background scales unaffected. Our results encourage further studies
of fNL with DESI spectroscopic samples, where the inclusion of 3D clustering
modes should help separate imaging systematics.Comment: 19 pages, 15 figures, 6 tables (Appendix excluded). Submitted to
MNRA
- âŠ