分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Weak lensing studies via cosmic voids are a promising probe of Modified Gravity (MG). The Excess Surface mass Density (ESD) is widely used as a lensing statistics in weak lensing researches. In this paper we use the ray-tracing method to study the ESD around voids in simulations based on the Cubic Galileon (CG) gravity. With the compilation of N-body simulation and ray-tracing method, changes on the structure formation and deflection angle resulting from MG can both be considered, making the extraction of lensing signals more realistic. We find good agreements between the measurement and theoretical prediction of ESD for CG gravity. Meanwhile, the effect on the deflection angle is found to be incomparable to that on the structure formation in CG, indicating an equivalence between ESD (statistics) and the projection of 3D dark matter density field for this gravity. Finally, we demonstrate that it is impossible to distinguish CG and General Relativity in our simulation with an effective survey area $\sim1550deg^2$ and a galaxy number density of $10arcmin^{-2}$, implying that void lensing statistics may not be the optimal probe on testing CG gravity. The methodology employed in this paper that combines N-body simulation and ray-tracing method can be a robust way to measure the lensing signals from simulations based on the MGs, and especially on that who significantly modifies the deflection angle.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Context. A novel high-performance exact pair counting toolkit called Fast Correlation Function Calculator (FCFC) is presented, which is publicly available at https://github.com/cheng-zhao/FCFC. Aims. As the rapid growth of modern cosmological datasets, the evaluation of correlation functions with observational and simulation catalogues has become a challenge. High-efficiency pair counting codes are thus in great demand. Methods. We introduce different data structures and algorithms that can be used for pair counting problems, and perform comprehensive benchmarks to identify the most efficient ones for real-world cosmological applications. We then describe the three levels of parallelisms used by FCFC -- including SIMD, OpenMP, and MPI -- and run extensive tests to investigate the scalabilities. Finally, we compare the efficiency of FCFC against alternative pair counting codes. Results. The data structures and histogram update algorithms implemented in FCFC are shown to outperform alternative methods. FCFC does not benefit much from SIMD as the bottleneck of our histogram update algorithm is mostly cache latency. Nevertheless, the efficiency of FCFC scales well with the numbers of OpenMP threads and MPI processes, albeit the speedups may be degraded with over a few thousand threads in total. FCFC is found to be faster than most (if not all) other public pair counting codes for modern cosmological pair counting applications.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Context. A novel high-performance exact pair counting toolkit called Fast Correlation Function Calculator (FCFC) is presented, which is publicly available at https://github.com/cheng-zhao/FCFC. Aims. As the rapid growth of modern cosmological datasets, the evaluation of correlation functions with observational and simulation catalogues has become a challenge. High-efficiency pair counting codes are thus in great demand. Methods. We introduce different data structures and algorithms that can be used for pair counting problems, and perform comprehensive benchmarks to identify the most efficient ones for real-world cosmological applications. We then describe the three levels of parallelisms used by FCFC -- including SIMD, OpenMP, and MPI -- and run extensive tests to investigate the scalabilities. Finally, we compare the efficiency of FCFC against alternative pair counting codes. Results. The data structures and histogram update algorithms implemented in FCFC are shown to outperform alternative methods. FCFC does not benefit much from SIMD as the bottleneck of our histogram update algorithm is mostly cache latency. Nevertheless, the efficiency of FCFC scales well with the numbers of OpenMP threads and MPI processes, albeit the speedups may be degraded with over a few thousand threads in total. FCFC is found to be faster than most (if not all) other public pair counting codes for modern cosmological pair counting applications.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Cheng Zhao
Chia-Hsun Chuang
Julian Bautista
Arnaud de Mattia
Anand Raichoor
Ashley J. Ross
Jiamin Hou
Richard Neveux
Charling Tao
Etienne Burtin
Kyle S. Dawson
Sylvain de la Torre
Héctor Gil-Marín
Jean-Paul Kneib
Will J. Percival
Graziano Rossi
Amélie Tamone
Jeremy L. Tinker
Gong-Bo Zhao
Shadab Alam
摘要： We produce 1000 realizations of synthetic clustering catalogues for each type of the tracers used for the baryon acoustic oscillation and redshift space distortion analysis of the Sloan Digital Sky Surveys-IV extended Baryon Oscillation Spectroscopic Survey final data release (eBOSS DR16), covering the redshift range from 0.6 to 2.2, to provide reliable estimates of covariance matrices and test the robustness of the analysis pipeline with respect to observational systematics. By extending the Zel'dovich approximation density field with an effective tracer bias model calibrated with the clustering measurements from the observational data, we accurately reproduce the two- and three-point clustering statistics of the eBOSS DR16 tracers, including their cross-correlations in redshift space with very low computational costs. In addition, we include the gravitational evolution of structures and sample selection biases at different redshifts, as well as various photometric and spectroscopic systematic effects. The agreements on the auto-clustering statistics between the data and mocks are generally within 1 $\sigma$ variances inferred from the mocks, for scales down to a few $h^{-1}\,{\rm Mpc}$ in configuration space, and up to $0.3\,h\,{\rm Mpc}^{-1}$ in Fourier space. For the cross correlations between different tracers, the same level of consistency presents in configuration space, while there are only discrepancies in Fourier space for scales above $0.15\,h\,{\rm Mpc}^{-1}$. The accurate reproduction of the data clustering statistics permits reliable covariances for multi-tracer analysis.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Zhejie Ding
Chia-Hsun Chuang
Yu Yu
Lehman H. Garrison
Adrian E. Bayer
Yu Feng
Chirag Modi
Daniel J. Eisenstein
Martin White
Andrei Variu
Cheng Zhao
Hanyu Zhang
Jennifer Meneses Rizo
David Brooks
Kyle Dawson
Peter Doel
Enrique Gaztanaga
Robert Kehoe
Alex Krolewski
Martin Landriau
摘要： Dark 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-$N$-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 $\sim 20$ 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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Cheng Zhao
Andrei Variu
Mengfan He
Daniel Forero Sanchez
Amélie Tamone
Chia-Hsun Chuang
Francisco-Shu Kitaura
Charling Tao
Jiaxi Yu
Jean-Paul Kneib
Will J. Percival
Huanyuan Shan
Gong-Bo Zhao
Etienne Burtin
Kyle S. Dawson
Graziano Rossi
Donald P. Schneider
Axel de la Macorra
摘要： We construct cosmic void catalogues with the DIVE void finder upon SDSS BOSS DR12 and eBOSS DR16 galaxy samples with BAO reconstruction applied, and perform a joint BAO analysis using different types of galaxies and the corresponding voids. The BAO peak is evident for the galaxy-galaxy, galaxy-void, and void-void correlation functions of all datasets, including the ones cross correlating luminous red galaxy and emission line galaxy samples. Two multi-tracer BAO fitting schemes are then tested, one combining the galaxy and void correlation functions with a weight applied to voids, and the other using a single BAO dilation parameter for all clustering measurements of different tracers. Both methods produce consistent results with mock catalogues, and on average ~10 per cent improvements of the BAO statistical uncertainties are observed for all samples, compared to the results from galaxies alone. By combining the clustering of galaxies and voids, the uncertainties of BAO measurements from the SDSS data are reduced by 5 to 15 per cent, yielding 0.9, 0.8, 1.1, 2.3, and 2.9 per cent constraints on the distance $D_{_{\rm V}}(z)$, at effective redshifts of 0.38, 0.51, 0.70, 0.77, and 0.85, respectively. When combined with BAO measurements from SDSS MGS, QSO, and Ly$\alpha$ samples, as well as the BBN results, we obtain $H_0 = 67.58 \pm 0.91\,{\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$, $\Omega_{\rm m} = 0.290 \pm 0.015$, and $\Omega_\Lambda h^2 = 0.3241 \pm 0.0079$ in the flat-$\Lambda$CDM framework, where the 1$\,\sigma$ uncertainties are around 6, 6, and 17 per cent smaller respectively, compared to constraints from the corresponding anisotropic BAO measurements without voids and LRG-ELG cross correlations.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Gong-Bo Zhao
Yuting Wang
Atsushi Taruya
Weibing Zhang
Hector Gil-Marin
Arnaud de Mattia
Ashley J. Ross
Anand Raichoor
Cheng Zhao
Will J. Percival
Shadab Alam
Julian E. Bautista
Etienne Burtin
Chia-Hsun Chuang
Jiamin Hou
Kyle S. Dawson
Jean-Paul Kneib
Kazuya Koyama
Helion du Mas des Bourboux
Eva-Maria Mueller
摘要： We perform a joint BAO and RSD analysis using the eBOSS DR16 LRG and ELG samples in the redshift range of $z\in[0.6,1.1]$, and detect a RSD signal from the cross power spectrum at a $\sim4\sigma$ confidence level, i.e., $f\sigma_8=0.317\pm0.080$ at $z_{\rm eff}=0.77$. Based on the chained power spectrum, which is a new development in this work to mitigate the angular systematics, we measurement the BAO distances and growth rate simultaneously at two effective redshifts, namely, $D_{\rm M}/r_{\rm d} \ (z=0.70)=17.96\pm0.51, \ D_{\rm H}/r_{\rm d} \ (z=0.70)=21.22\pm1.20, \ f\sigma_8 \ (z=0.70) =0.43\pm0.05$, and $D_{\rm M}/r_{\rm d} \ (z=0.845)=18.90\pm0.78, \ D_{\rm H}/r_{\rm d} \ (z=0.845)=20.91\pm2.86, \ f\sigma_8 \ (z=0.845) =0.30\pm0.08$. Combined with BAO measurements including those from the eBOSS DR16 QSO and Lyman-$\alpha$ sample, our measurement has raised the significance level of a nonzero $\Omega_{\rm \Lambda}$ to $\sim11\sigma$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Agne Semenaite
Ariel G. Sánchez
Andrea Pezzotta
Jiamin Hou
Alexander Eggemeier
Martin Crocce
Cheng Zhao
Joel R. Brownstein
Graziano Rossi
Donald P. Schneider
摘要： We analyse the full shape of anisotropic clustering measurements from the extended Baryon Oscillation Spectroscopic survey (eBOSS) quasar sample together with the combined galaxy sample from the Baryon Oscillation Spectroscopic Survey (BOSS). We obtain constraints on the cosmological parameters independent of the Hubble parameter $h$ for the extensions of the $\Lambda$CDM models, focusing on cosmologies with free dark energy equation of state parameter $w$. We combine the clustering constraints with those from the latest CMB data from Planck to obtain joint constraints for these cosmologies for $w$ and the additional extension parameters - its time evolution $w_{\rm{a}}$, the physical curvature density $\omega_{K}$ and the neutrino mass sum $\sum m_{\nu}$. Our joint constraints are consistent with flat $\Lambda$CDM cosmological model within 68\% confidence limits. We demonstrate that the Planck data are able to place tight constraints on the clustering amplitude today, $\sigma_{12}$, in cosmologies with varying $w$ and present the first constraints for the clustering amplitude for such cosmologies, which is found to be slightly higher than the $\Lambda$CDM value. Additionally, we show that when we vary $w$ and allow for non-flat cosmologies and the physical curvature density is used, Planck prefers a curved universe at $4\sigma$ significance, which is $\sim2\sigma$ higher than when using the relative curvature density $\Omega_{\rm{K}}$. Finally, when $w$ is varied freely, clustering provides only a modest improvement (of 0.021 eV) on the upper limit of $\sum m_{\nu}$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Andrei Variu
Cheng Zhao
Daniel Forero-Sánchez
Chia-Hsun Chuang
Francisco-Shu Kitaura
Charling Tao
Amélie Tamone
Jean-Paul Kneib
摘要： Baryonic Acoustic Oscillations (BAOs) studies based on the clustering of voids and matter tracers provide important constraints on cosmological parameters related to the expansion of the Universe. However, modelling the void exclusion effect is an important challenge for fully exploiting the potential of these kind of analyses. We thus develop two numerical methods to describe the clustering of cosmic voids. Neither model requires additional cosmological information beyond that assumed within the galaxy de-wiggled model. The models consist in power spectra whose performance we assess in comparison to a parabolic model on both Patchy boxes and light-cones. Moreover, we test their robustness against systematic effects and the reconstruction technique. The void model power spectra and the parabolic model with a fixed parameter provide strongly correlated values for the Alcock-Paczynski ($\alpha$) parameter, for boxes and light-cones likewise. The resulting $\alpha$ values - for all three models - are unbiased and their uncertainties are correctly estimated. However, the numerical models show less variation with the fitting range compared to the parabolic one. The Bayesian evidence suggests that the numerical techniques are often favoured compared to the parabolic model. Moreover, the void model power spectra computed on boxes can describe the void clustering from light-cones as well as from boxes. The same void model power spectra can be used for the study of pre- and post-reconstructed data-sets. Lastly, the two numerical techniques are resilient against the studied systematic effects. Consequently, using either of the two new void models, one can more robustly measure cosmological parameters.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Weak lensing studies via cosmic voids are a promising probe of Modified Gravity (MG). The Excess Surface mass Density (ESD) is widely used as a lensing statistics in weak lensing researches. In this paper we use the ray-tracing method to study the ESD around voids in simulations based on the Cubic Galileon (CG) gravity. With the compilation of N-body simulation and ray-tracing method, changes on the structure formation and deflection angle resulting from MG can both be considered, making the extraction of lensing signals more realistic. We find good agreements between the measurement and theoretical prediction of ESD for CG gravity. Meanwhile, the effect on the deflection angle is found to be incomparable to that on the structure formation in CG, indicating an equivalence between ESD (statistics) and the projection of 3D dark matter density field for this gravity. Finally, we demonstrate that it is impossible to distinguish CG and General Relativity in our simulation with an effective survey area $\sim1550deg^2$ and a galaxy number density of $10arcmin^{-2}$, implying that void lensing statistics may not be the optimal probe on testing CG gravity. The methodology employed in this paper that combines N-body simulation and ray-tracing method can be a robust way to measure the lensing signals from simulations based on the MGs, and especially on that who significantly modifies the deflection angle.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Next-generation spectroscopic surveys such as the MegaMapper, MUltiplexed Survey Telescope (MUST), MaunaKea Spectroscopic Explorer (MSE), and Wide Spectroscopic Telescope (WST) are foreseen to increase the number of galaxy/quasar redshifts by an order of magnitude, with hundred millions of spectra that will be measured at $z>2$. We perform a Fisher matrix analysis for these surveys on the baryonic acoustic oscillation (BAO), the redshift-space distortion (RSD) measurement, the non-Gaussianity amplitude $f_{\rm NL}$, and the total neutrino mass $M_\nu$. For BAO and RSD parameters, these surveys may achieve precision at sub-percent level (<0.5 per cent), representing an improvement of factor 10 w.r.t. the latest database. For NG, these surveys may reach an accuracy of $\sigma(f_{\rm NL})\sim 1$. They can also put a tight constraint on $M_\nu$ with $\sigma(M_\nu) \sim 0.02\,\rm eV$ if we do joint analysis with Planck and even $ 0.01\,\rm eV$ if combined with other data. In addition, we introduce a general survey model, to derive the cosmic volume and number density of tracers, given instrumental facilities and survey strategy. Using our Fisher formalism, we can explore (continuously) a wide range of survey observational parameters, and propose different survey strategies that optimise the cosmological constraints. Fixing the fibre number and survey duration, we show that the best strategy for $f_{\rm NL}$ and $M_\nu$ measurement is to observe large volumes, despite the noise increase. However, the strategy differs for the apparent magnitude limit. Finally, we prove that increasing the fibre number improves $M_{\nu}$ measurement but not significantly $f_{\rm NL}$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jiaxi Yu
Cheng Zhao
Chia-Hsun Chuang
Julian Bautista
Ginevra Favole
Jean-Paul Kneib
Faizan Mohammad
Ashley Ross
Anand Raichoor
Charling Tao
Kyle Dawson
Graziano Rossi
摘要： SubHalo Abundance Matching (SHAM) is an empirical method for constructing
galaxy catalogues based on high-resolution $N$-body simulations. We apply SHAM
on the UNIT simulation to simulate SDSS BOSS/eBOSS Luminous Red Galaxies (LRGs)
within a wide redshift range of $0.2 < z < 1.0$. Besides the typical SHAM
scatter parameter $\sigma$, we include $v_{\rm smear}$ and $V_{\rm ceil}$ to
take into account the redshift uncertainty and the galaxy incompleteness
respectively. These two additional parameters are critical for reproducing the
observed 2PCF multipoles on 5--25$\,h^{-1}\,{\rm Mpc}$. The redshift
uncertainties obtained from the best-fitting $v_{\rm smear}$ agree with those
measured from repeat observations for all SDSS LRGs except for the LOWZ sample.
We explore several potential systematics but none of them can explain the
discrepancy found in LOWZ. Our explanation is that the LOWZ galaxies might
contain another type of galaxies which needs to be treated differently. The
evolution of the measured $\sigma$ and $V_{\rm ceil}$ also reveals that the
incompleteness of eBOSS galaxies decreases with the redshift. This is the
consequence of the magnitude lower limit applied in eBOSS LRG target selection.
Our SHAM also set upper limits for the intrinsic scatter of the galaxy--halo
relation given a complete galaxy sample: $\sigma_{\rm int}<0.31$ for LOWZ at
$0.2
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Andrés Balaguera-Antolínez
Francisco-Shu Kitaura
Shadab Alam
Chia-Hsun Chuang
Yu Yu
Ginevra Favole
Cheng Zhao
David Brooks
Axel de la Macorra
Andreu Font-Ribera
Satya Gontcho A Gontcho
Klaus Honscheid
Robert Kehoe
Aron Meisner
Ramon Miquel
Gregory Tarlè
Mariana Vargas-Magaña
Zhimin Zhou
摘要： This work presents for the first time galaxy catalogues constructed based on halo distributions obtained with effective bias models at the field level. In particular, it relies on the Bias Assignment Method (BAM) and explores the accuracy in the summary statistics using different non-local dependencies in the halo bias. Moreover, improvements in the hierarchy of halo properties assignment are introduced, which are key to accurately applying halo occupation distribution (HOD) to construct emission-line galaxy catalogues, target for experiments such as the Dark Energy Spectroscopic Instrument (DESI). We introduce novel cosmic-web dependent corrections to the analytical velocity field, to model redshift space distortions at the N-body level -- both in the halo and galaxy distributions -- in the monopole, quadrupole, and hexadecapole up to $k\sim0.3\,h^{-1}{\rm Mpc}$. We demonstrate the high accuracy of the mocks in the one (abundance), two- (e.g. power spectrum), three- (e.g. bispectrum), four- (covariance matrices of two-point statistics), and six-point statistics (covariance matrices of three-point statistics), both in real and redshift space. BAM offers a robust way to produce fast and accurate halo distributions which can be used to generate a variety of multi-tracer catalogs with precise covariance matrices of several cosmological probes.
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