分类： 天文学 >> 天文学 提交时间： 2023-02-19
C. Zhou
A. Tong
M. A. Troxel
J. Blazek
C. Lin
D. Bacon
L. Bleem
A. Carnero Rosell
C. Chang
M. Costanzi
J. DeRose
J. P. Dietrich
A. Drlica-Wagner
D. Gruen
R. A. Gruendl
B. Hoyle
M. Jarvis
N. MacCrann
B. Mawdsley
T. McClintock
摘要： Clusters of galaxies are sensitive to the most nonlinear peaks in the cosmic density field. The weak gravitational lensing of background galaxies by clusters can allow us to infer their masses. However, galaxies associated with the local environment of the cluster can also be intrinsically aligned due to the local tidal gradient, contaminating any cosmology derived from the lensing signal. We measure this intrinsic alignment in Dark Energy Survey (DES) Year 1 redMaPPer clusters. We find evidence of a non-zero mean radial alignment of galaxies within clusters between redshift 0.1-0.7. We find a significant systematic in the measured ellipticities of cluster satellite galaxies that we attribute to the central galaxy flux and other intracluster light. We attempt to correct this signal, and fit a simple model for intrinsic alignment amplitude ($A_{\textrm{IA}}$) to the measurement, finding $A_{\textrm{IA}}=0.15\pm 0.04$, when excluding data near the edge of the cluster. We find a significantly stronger alignment of the central galaxy with the cluster dark matter halo at low redshift and with higher richness and central galaxy absolute magnitude (proxies for cluster mass). This is an important demonstration of the ability of large photometric data sets like DES to provide direct constraints on the intrinsic alignment of galaxies within clusters. These measurements can inform improvements to small-scale modeling and simulation of the intrinsic alignment of galaxies to help improve the separation of the intrinsic alignment signal in weak lensing studies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
A. Biekert
C. Chang
L. Chaplinsky
C. W. Fink
W. D. Frey
M. Garcia-Sciveres
W. Guo
S. A. Hertel
X. Li
J. Lin
M. Lisovenko
R. Mahapatra
D. N. McKinsey
S. Mehrotra
N. Mirabolfathi
P. K. Patel
B. Penning
H. D. Pinckney
M. Reed
R. K. Romani
摘要： A portable monoenergetic 24 keV neutron source based on the $^{124}$Sb-$^9$Be photoneutron reaction and an iron filter has been constructed and characterized. The coincidence of the neutron energy from SbBe and the low interaction cross-section with iron (mean free path up to 29 cm) makes pure iron specially suited to shield against gamma rays from $^{124}$Sb decays while letting through the neutrons. To increase the $^{124}$Sb activity and thus the neutron flux, a $>$1 GBq $^{124}$Sb source was produced by irradiating a natural Sb metal pellet with a high flux of thermal neutrons in a nuclear reactor. The design of the source shielding structure makes for easy transportation and deployment. A hydrogen gas proportional counter is used to characterize the neutrons emitted by the source and a NaI detector is used for gamma background characterization. At the exit opening of the neutron beam, the characterization determined the neutron flux in the energy range 20-25 keV to be 5.36$\pm$0.20 neutrons per cm$^2$ per second and the total gamma flux to be 213$\pm$6 gammas per cm$^2$ per second (numbers scaled to 1 GBq activity of the $^{124}$Sb source). A liquid scintillator detector is demonstrated to be sensitive to neutrons with incident kinetic energies from 8 to 17 keV, so it can be paired with the source as a backing detector for neutron scattering calibration experiments. This photoneutron source provides a good tool for in-situ low energy nuclear recoil calibration for dark matter experiments and coherent elastic neutrino-nucleus scattering experiments.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. Prat
J. Zuntz
Y. Omori
C. Chang
T. Tröster
E. Pedersen
C. García-García
E. Phillips-Longley
J. Sanchez
D. Alonso
E. Gawiser
K. Heitmann
M. Ishak
M. Jarvis
E. Kovacs
P. Larsen
Y. -Y. Mao
L. Medina Varela
Z. Zhang
The LSST Dark Energy Science Collaboration
摘要： We present TXPipe, a modular, automated and reproducible pipeline for generating data vectors in cosmology analyses. The pipeline is developed within the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration (DESC), and designed for cosmology analyses using LSST data. In this paper, we present the pipeline for the so-called 3$\times$2pt analysis - a combination of three two-point functions that measure the auto- and cross-correlation between galaxy density and shapes. We perform the analysis both in real and harmonic space using TXPipe and other LSST-DESC tools. We validate the pipeline using Gaussian simulations and show that the pipeline accurately measures data vectors and recovers the input cosmology to the accuracy level required for the first year of LSST data. We also apply the pipeline to a realistic mock galaxy sample extracted from the CosmoDC2 simulation suite Korytov et al. (2019). TXPipe establishes a baseline framework that can be built upon as the LSST survey proceeds. Furthermore, the pipeline is designed to be easily extended to science probes beyond the 3$\times$2pt analysis.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
A. Amon
D. Gruen
M. A. Troxel
N. MacCrann
S. Dodelson
A. Choi
C. Doux
L. F. Secco
S. Samuroff
E. Krause
J. Cordero
J. Myles
J. DeRose
R. H. Wechsler
M. Gatti
A. Navarro-Alsina
G. M. Bernstein
B. Jain
J. Blazek
A. Alarcon
摘要： This work, together with its companion paper, Secco and Samuroff et al. (2021), presents the Dark Energy Survey Year 3 cosmic shear measurements and cosmological constraints based on an analysis of over 100 million source galaxies. With the data spanning 4143 deg$^2$ on the sky, divided into four redshift bins, we produce the highest significance measurement of cosmic shear to date, with a signal-to-noise of 40. We conduct a blind analysis in the context of the $\Lambda$CDM model and find a 3% constraint of the clustering amplitude, $S_8\equiv \sigma_8 (\Omega_{\rm m}/0.3)^{0.5} = 0.759^{+0.025}_{-0.023}$. A $\Lambda$CDM-Optimized analysis, which safely includes smaller scale information, yields a 2% precision measurement of $S_8= 0.772^{+0.018}_{-0.017}$ that is consistent with the fiducial case. The two low-redshift measurements are statistically consistent with the Planck Cosmic Microwave Background result, however, both recovered $S_8$ values are lower than the high-redshift prediction by $2.3\sigma$ and $2.1\sigma$ ($p$-values of 0.02 and 0.05), respectively. The measurements are shown to be internally consistent across redshift bins, angular scales and correlation functions. The analysis is demonstrated to be robust to calibration systematics, with the $S_8$ posterior consistent when varying the choice of redshift calibration sample, the modeling of redshift uncertainty and methodology. Similarly, we find that the corrections included to account for the blending of galaxies shifts our best-fit $S_8$ by $0.5\sigma$ without incurring a substantial increase in uncertainty. We examine the limiting factors for the precision of the cosmological constraints and find observational systematics to be subdominant to the modeling of astrophysics. Specifically, we identify the uncertainties in modeling baryonic effects and intrinsic alignments as the limiting systematics.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. Sánchez
Y. Omori
C. Chang
L. E. Bleem
T. Crawford
A. Drlica-Wagner
S. Raghunathan
G. Zacharegkas
T. M. C. Abbott
M. Aguena
A. Alarcon
S. Allam
O. Alves
A. Amon
S. Avila
E. Baxter
K. Bechtol
B. A. Benson
G. M. Bernstein
E. Bertin
摘要： We cross-correlate positions of galaxies measured in data from the first three years of the Dark Energy Survey with Compton-$y$-maps generated using data from the South Pole Telescope (SPT) and the {\it Planck} mission. We model this cross-correlation measurement together with the galaxy auto-correlation to constrain the distribution of gas in the Universe. We measure the hydrostatic mass bias or, equivalently, the mean halo bias-weighted electron pressure $\langle b_{h}P_{e}\rangle$, using large-scale information. We find $\langle b_{h}P_{e}\rangle$ to be $[0.16^{+0.03}_{-0.04},0.28^{+0.04}_{-0.05},0.45^{+0.06}_{-0.10},0.54^{+0.08}_{-0.07},0.61^{+0.08}_{-0.06},0.63^{+0.07}_{-0.08}]$ meV cm$^{-3}$ at redshifts $z \sim [0.30, 0.46, 0.62,0.77, 0.89, 0.97]$. These values are consistent with previous work where measurements exist in the redshift range. We also constrain the mean gas profile using small-scale information, enabled by the high-resolution of the SPT data. We compare our measurements to different parametrized profiles based on the cosmo-OWLS hydrodynamical simulations. We find that our data are consistent with the simulation that assumes an AGN heating temperature of $10^{8.5}$K but are incompatible with the model that assumes an AGN heating temperature of $10^{8.0}$K. These comparisons indicate that the data prefer a higher value of electron pressure than the simulations within $r_{500c}$ of the galaxies' halos.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. Prat
G. Zacharegkas
Y. Park
N. MacCrann
E. R. Switzer
S. Pandey
C. Chang
J. Blazek
R. Miquel
A. Alarcon
O. Alves
A. Amon
F. Andrade-Oliveira
K. Bechtol
M. R. Becker
G. M. Bernstein
R. Chen
A. Choi
H. Camacho
A. Campos
摘要： Recent cosmological analyses with large-scale structure and weak lensing measurements, usually referred to as 3$\times$2pt, had to discard a lot of signal-to-noise from small scales due to our inability to precisely model non-linearities and baryonic effects. Galaxy-galaxy lensing, or the position-shear correlation between lens and source galaxies, is one of the three two-point correlation functions that are included in such analyses, usually estimated with the mean tangential shear. However, tangential shear measurements at a given angular scale $\theta$ or physical scale $R$ carry information from all scales below that, forcing the scale cuts applied in real data to be significantly larger than the scale at which theoretical uncertainties become problematic. Recently there have been a few independent efforts that aim to mitigate the non-locality of the galaxy-galaxy lensing signal. Here we perform a comparison of the different methods, including the Y transformation described in Park et al. (2021), the point-mass marginalization methodology presented in MacCrann et al. (2020) and the Annular Differential Surface Density statistic described in Baldauf et al. (2010). We do the comparison at the cosmological constraints level in a noiseless simulated combined galaxy clustering and galaxy-galaxy lensing analysis. We find that all the estimators perform equivalently using a Rubin Observatory Legacy Survey of Space and Time (LSST) Year 1 like setup. This is because all the estimators project out the mode responsible for the non-local nature of the galaxy-galaxy lensing measurements, which we have identified as $1/R^2$. We finally apply all the estimators to DES Y3 data and confirm that they all give consistent results.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
DES Collaboration
T. M. C. Abbott
M. Aguena
A. Alarcon
O. Alves
A. Amon
J. Annis
S. Avila
D. Bacon
E. Baxter
K. Bechtol
M. R. Becker
G. M. Bernstein
S. Birrer
J. Blazek
S. Bocquet
A. Brandao-Souza
S. L. Bridle
D. Brooks
D. L. Burke
摘要： We constrain extensions to the $\Lambda$CDM model using measurements from the Dark Energy Survey's first three years of observations and external data. The DES data are the two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. We use simulated data and blind analyses of real data to validate the robustness of our results. In many cases, constraining power is limited by the absence of nonlinear predictions that are reliable at our required precision. The models are: dark energy with a time-dependent equation of state, non-zero spatial curvature, sterile neutrinos, modifications of gravitational physics, and a binned $\sigma_8(z)$ model which serves as a probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find $(w_{\rm p}, w_a)= (-0.99^{+0.28}_{-0.17},-0.9\pm 1.2)$ at 68% confidence with $z_{\rm p}=0.24$ from the DES measurements alone, and $(w_{\rm p}, w_a)= (-1.03^{+0.04}_{-0.03},-0.4^{+0.4}_{-0.3})$ with $z_{\rm p}=0.21$ for the combination of all data considered. Curvature constraints of $\Omega_k=0.0009\pm 0.0017$ and effective relativistic species $N_{\rm eff}=3.10^{+0.15}_{-0.16}$ are dominated by external data. For massive sterile neutrinos, we improve the upper bound on the mass $m_{\rm eff}$ by a factor of three compared to previous analyses, giving 95% limits of $(\Delta N_{\rm eff},m_{\rm eff})\leq (0.28, 0.20\, {\rm eV})$. We also constrain changes to the lensing and Poisson equations controlled by functions $\Sigma(k,z) = \Sigma_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}$ and $\mu(k,z)=\mu_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}$ respectively to $\Sigma_0=0.6^{+0.4}_{-0.5}$ from DES alone and $(\Sigma_0,\mu_0)=(0.04\pm 0.05,0.08^{+0.21}_{-0.19})$ for the combination of all data. Overall, we find no significant evidence for physics beyond $\Lambda$CDM.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
S. Pandey
M. Gatti
E. Baxter
J. C. Hill
X. Fang
C. Doux
G. Giannini
M. Raveri
J. DeRose
H. Huang
E. Moser
N. Battaglia
A. Alarcon
A. Amon
M. Becker
A. Campos
C. Chang
R. Chen
A. Choi
K. Eckert
摘要： Hot, ionized gas leaves an imprint on the cosmic microwave background via the thermal Sunyaev Zel'dovich (tSZ) effect. The cross-correlation of gravitational lensing (which traces the projected mass) with the tSZ effect (which traces the projected gas pressure) is a powerful probe of the thermal state of ionized baryons throughout the Universe, and is sensitive to effects such as baryonic feedback. In a companion paper (Gatti et al. 2021), we present tomographic measurements and validation tests of the cross-correlation between galaxy shear measurements from the first three years of observations of the Dark Energy Survey, and tSZ measurements from a combination of Atacama Cosmology Telescope and ${\it Planck}$ observations. In this work, we use the same measurements to constrain models for the pressure profiles of halos across a wide range of halo mass and redshift. We find evidence for reduced pressure in low mass halos, consistent with predictions for the effects of feedback from active galactic nuclei. We infer the hydrostatic mass bias ($B \equiv M_{500c}/M_{\rm SZ}$) from our measurements, finding $B = 1.8\pm0.1$ when adopting the ${\it Planck}$-preferred cosmological parameters. We additionally find that our measurements are consistent with a non-zero redshift evolution of $B$, with the correct sign and sufficient magnitude to explain the mass bias necessary to reconcile cluster count measurements with the ${\it Planck}$-preferred cosmology. Our analysis introduces a model for the impact of intrinsic alignments (IA) of galaxy shapes on the shear-tSZ correlation. We show that IA can have a significant impact on these correlations at current noise levels.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
S. Samuroff
R. Mandelbaum
J. Blazek
A. Campos
N. MacCrann
G. Zacharegkas
A. Amon
J. Prat
S. Singh
J. Elvin-Poole
A. J. Ross
A. Alarcon
E. Baxter
K. Bechtol
M. R. Becker
G. M. Bernstein
A. Carnero Rosell
M. Carrasco Kind
R. Cawthon
C. Chang
摘要： We present direct constraints on galaxy intrinsic alignments using the Dark
Energy Survey Year 3 (DES Y3), the Extended Baryon Oscillation Spectroscopic
Survey (eBOSS) and its precursor, the Baryon Oscillation Spectroscopic Survey
(BOSS). Our measurements incorporate photometric red sequence (redMaGiC)
galaxies from DES with median redshift $z\sim0.2-1.0$, luminous red galaxies
(LRGs) from eBOSS at $z\sim0.8$, and also a SDSS-III BOSS CMASS sample at
$z\sim0.5$. We measure two point intrinsic alignment correlations, which we fit
using a model that includes lensing, magnification and photometric redshift
error. Fitting on scales $6
分类： 天文学 >> 天文学 提交时间： 2023-02-19
C. Sánchez
A. Alarcon
G. M. Bernstein
J. Sanchez
S. Pandey
M. Raveri
J. Prat
N. Weaverdyck
I. Sevilla-Noarbe
C. Chang
E. Baxter
Y. Omori
B. Jain
O. Alves
A. Amon
K. Bechtol
M. R. Becker
J. Blazek
A. Choi
A. Campos
摘要： The fiducial cosmological analyses of imaging galaxy surveys like the Dark Energy Survey (DES) typically probe the Universe at redshifts $z < 1$. This is mainly because of the limited depth of these surveys, and also because such analyses rely heavily on galaxy lensing, which is more efficient at low redshifts. In this work we present the selection and characterization of high-redshift galaxy samples using DES Year 3 data, and the analysis of their galaxy clustering measurements. In particular, we use galaxies that are fainter than those used in the previous DES Year 3 analyses and a Bayesian redshift scheme to define three tomographic bins with mean redshifts around $z \sim 0.9$, $1.2$ and $1.5$, which significantly extend the redshift coverage of the fiducial DES Year 3 analysis. These samples contain a total of about 9 million galaxies, and their galaxy density is more than 2 times higher than those in the DES Year 3 fiducial case. We characterize the redshift uncertainties of the samples, including the usage of various spectroscopic and high-quality redshift samples, and we develop a machine-learning method to correct for correlations between galaxy density and survey observing conditions. The analysis of galaxy clustering measurements, with a total signal-to-noise $S/N \sim 70$ after scale cuts, yields robust cosmological constraints on a combination of the fraction of matter in the Universe $\Omega_m$ and the Hubble parameter $h$, $\Omega_m h = 0.195^{+0.023}_{-0.018}$, and 2-3% measurements of the amplitude of the galaxy clustering signals, probing galaxy bias and the amplitude of matter fluctuations, $b \sigma_8$. A companion paper $\textit{(in preparation)}$ will present the cross-correlations of these high-$z$ samples with CMB lensing from Planck and SPT, and the cosmological analysis of those measurements in combination with the galaxy clustering presented in this work.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
S. Pandey
E. Krause
J. DeRose
N. MacCrann
B. Jain
M. Crocce
J. Blazek
A. Choi
H. Huang
C. To
X. Fang
J. Elvin-Poole
J. Prat
A. Porredon
L. F. Secco
M. Rodriguez-Monroy
N. Weaverdyck
Y. Park
M. Raveri
E. Rozo
摘要： We constrain cosmological and galaxy-bias parameters using the combination of galaxy clustering and galaxy-galaxy lensing measurements from the Dark Energy Survey Year-3 data. We describe our modeling framework, and choice of scales analyzed, validating their robustness to theoretical uncertainties in small-scale clustering by analyzing simulated data. Using a linear galaxy bias model and redMaGiC galaxy sample, we obtain constraints on the matter density to be $\Omega_{\rm m} = 0.325^{+0.033}_{-0.034}$. We also implement a non-linear galaxy bias model to probe smaller scales that includes parameterization based on hybrid perturbation theory and find that it leads to a 17% gain in cosmological constraining power. We perform robustness tests of our methodology pipeline and demonstrate the stability of the constraints to changes in the theoretical model. Using the redMaGiC galaxy sample as foreground lens galaxies, we find the galaxy clustering and galaxy-galaxy lensing measurements to exhibit significant signals akin to de-correlation between galaxies and mass on large scales, which is not expected in any current models. This likely systematic measurement error biases our constraints on galaxy bias and the $S_8$ parameter. We find that a scale-, redshift- and sky-area-independent phenomenological de-correlation parameter can effectively capture the impact of this systematic error. We trace the source of this de-correlation to a color-dependent photometric issue and minimize its impact on our result by changing the selection criteria of redMaGiC galaxies. Using this new sample, our constraints on the $S_8$ parameter are consistent with previous studies, and we find a small shift in the $\Omega_{\rm m}$ constraints compared to the fiducial redMaGiC sample. We constrain the mean host halo mass of the redMaGiC galaxies in this new sample to be approximately $1.6 \times 10^{13} M_{\odot}/h$.
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