分类： 天文学 >> 天文学 提交时间： 2023-02-19
Euclid Collaboration
H. Bretonnière
U. Kuchner
M. Huertas-Company
E. Merlin
M. Castellano
D. Tuccillo
F. Buitrago
C. J. Conselice
A. Boucaud
B. Häußler
M. Kümmel
W. G. Hartley
A. Alvarez Ayllon
E. Bertin
F. Ferrari
L. Ferreira
R. Gavazzi
D. Hernández-Lang
G. Lucatelli
摘要： The various Euclid imaging surveys will become a reference for studies of galaxy morphology by delivering imaging over an unprecedented area of 15 000 square degrees with high spatial resolution. In order to understand the capabilities of measuring morphologies from Euclid-detected galaxies and to help implement measurements in the pipeline, we have conducted the Euclid Morphology Challenge, which we present in two papers. While the companion paper by Merlin et al. focuses on the analysis of photometry, this paper assesses the accuracy of the parametric galaxy morphology measurements in imaging predicted from within the Euclid Wide Survey. We evaluate the performance of five state-of-the-art surface-brightness-fitting codes DeepLeGATo, Galapagos-2, Morfometryka, Profit and SourceXtractor++ on a sample of about 1.5 million simulated galaxies resembling reduced observations with the Euclid VIS and NIR instruments. The simulations include analytic S\'ersic profiles with one and two components, as well as more realistic galaxies generated with neural networks. We find that, despite some code-specific differences, all methods tend to achieve reliable structural measurements (10% scatter on ideal S\'ersic simulations) down to an apparent magnitude of about 23 in one component and 21 in two components, which correspond to a signal-to-noise ratio of approximately 1 and 5 respectively. We also show that when tested on non-analytic profiles, the results are typically degraded by a factor of 3, driven by systematics. We conclude that the Euclid official Data Releases will deliver robust structural parameters for at least 400 million galaxies in the Euclid Wide Survey by the end of the mission. We find that a key factor for explaining the different behaviour of the codes at the faint end is the set of adopted priors for the various structural parameters.
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. 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
H. Camacho
F. Andrade-Oliveira
A. Troja
R. Rosenfeld
L. Faga
R. Gomes
C. Doux
X. Fang
M. Lima
V. Miranda
T. F. Eifler
O. Friedrich
M. Gatti
G. M. Bernstein
J. Blazek
S. L. Bridle
A. Choi
C. Davis
J. DeRose
E. Gaztanaga
摘要： We perform a cosmic shear analysis in harmonic space using the first year of data collected by the Dark Energy Survey (DES-Y1). We measure the cosmic weak lensing shear power spectra using the Metacalibration catalogue and perform a likelihood analysis within the framework of CosmoSIS. We set scale cuts based on baryonic effects contamination and model redshift and shear calibration uncertainties as well as intrinsic alignments. We adopt as fiducial covariance matrix an analytical computation accounting for the mask geometry in the Gaussian term, including non-Gaussian contributions. A suite of 1200 lognormal simulations is used to validate the harmonic space pipeline and the covariance matrix. We perform a series of stress tests to gauge the robustness of the harmonic space analysis. Finally, we use the DES-Y1 pipeline in configuration space to perform a similar likelihood analysis and compare both results, demonstrating their compatibility in estimating the cosmological parameters $S_8$, $\sigma_8$ and $\Omega_m$. The methods implemented and validated in this paper will allow us to perform a consistent harmonic space analysis in the upcoming DES data.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
A. Amon
N. C. Robertson
H. Miyatake
C. Heymans
M. White
J. DeRose
S. Yuan
R. H. Wechsler
T. N. Varga
S. Bocquet
A. Dvornik
S. More
A. J. Ross
H. Hoekstra
A. Alarcon
M. Asgari
J. Blazek
A. Campos
R. Chen
A. Choi
摘要： We evaluate the consistency between lensing and clustering probes of
large-scale structure based on measurements of projected galaxy clustering from
BOSS combined with overlapping galaxy-galaxy lensing from three surveys: DES
Y3, HSC Y1, and KiDS-1000. An intra-lensing-survey study finds good agreement
between these lensing data. We model the observations using the Dark Emulator
and fit the data at two fixed cosmologies: Planck, with $S_8=0.83$, and a
Lensing cosmology with $S_8=0.76$. For a joint analysis limited to scales with
$R>5.25h^{-1}$Mpc, we find that both cosmologies provide an acceptable fit to
the data. Full utilisation of the small-scale clustering and lensing
measurements is hindered by uncertainty in the impact of baryon feedback and
assembly bias, which we account for with a reasoned theoretical error budget.
We incorporate a systematic scaling parameter for each redshift bin, $A$, that
decouples the lensing and clustering to capture any inconsistency. When a wide
range of scales ($0.15
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
A. Porredon
M. Crocce
J. Elvin-Poole
R. Cawthon
G. Giannini
J. De Vicente
A. Carnero Rosell
I. Ferrero
E. Krause
X. Fang
J. Prat
M. Rodriguez-Monroy
S. Pandey
A. Pocino
F. J. Castander
A. Choi
A. Amon
I. Tutusaus
S. Dodelson
I. Sevilla-Noarbe
摘要： Two of the most sensitive probes of the large scale structure of the universe are the clustering of galaxies and the tangential shear of background galaxy shapes produced by those foreground galaxies, so-called galaxy-galaxy lensing. Combining the measurements of these two two-point functions leads to cosmological constraints that are independent of the galaxy bias factor. The optimal choice of foreground, or lens, galaxies is governed by the joint, but conflicting requirements to obtain accurate redshift information and large statistics. We present cosmological results from the full 5000 sq. deg. of the Dark Energy Survey first three years of observations (Y3) combining those two-point functions, using for the first time a magnitude-limited lens sample (MagLim) of 11 million galaxies especially selected to optimize such combination, and 100 million background shapes. We consider two cosmological models, flat $\Lambda$CDM and $w$CDM. In $\Lambda$CDM we obtain for the matter density $\Omega_m = 0.320^{+0.041}_{-0.034}$ and for the clustering amplitude $S_8 = 0.778^{+0.037}_{-0.031}$, at 68% C.L. The latter is only 1$\sigma$ smaller than the prediction in this model informed by measurements of the cosmic microwave background by the Planck satellite. In $w$CDM we find $\Omega_m = 0.32^{+0.044}_{-0.046}$, $S_8=0.777^{+0.049}_{-0.051}$, and dark energy equation of state $w=-1.031^{+0.218}_{-0.379}$. We find that including smaller scales while marginalizing over non-linear galaxy bias improves the constraining power in the $\Omega_m-S_8$ plane by $31$% and in the $\Omega_m-w$ plane by $41$% while yielding consistent cosmological parameters from those in the linear bias case. These results are combined with those from cosmic shear in a companion paper to present full DES-Y3 constraints from the three two-point functions (3x2pt).
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
J. Myles
D. Gruen
A. Amon
A. Alarcon
J. DeRose
S. Everett
S. Dodelson
G. M. Bernstein
A. Campos
I. Harrison
N. MacCrann
J. McCullough
M. Raveri
C. Sánchez
M. A. Troxel
B. Yin
T. M. C. Abbott
S. Allam
O. Alves
F. Andrade-Oliveira
摘要： We present a method for mapping variations between probability distribution functions and apply this method within the context of measuring galaxy redshift distributions from imaging survey data. This method, which we name PITPZ for the probability integral transformations it relies on, uses a difference in curves between distribution functions in an ensemble as a transformation to apply to another distribution function, thus transferring the variation in the ensemble to the latter distribution function. This procedure is broadly applicable to the problem of uncertainty propagation. In the context of redshift distributions, for example, the uncertainty contribution due to certain effects can be studied effectively only in simulations, thus necessitating a transfer of variation measured in simulations to the redshift distributions measured from data. We illustrate the use of PITPZ by using the method to propagate photometric calibration uncertainty to redshift distributions of the Dark Energy Survey Year 3 weak lensing source galaxies. For this test case, we find that PITPZ yields a lensing amplitude uncertainty estimate due to photometric calibration error within 1 per cent of the truth, compared to as much as a 30 per cent underestimate when using traditional methods.
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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