Pub Date : 2020-09-16DOI: 10.1103/PHYSREVD.103.063507
C. Vergès, J. Errard, R. Stompor
Reaching the sufficient sensitivity to detect primordial B-modes requires modern CMB polarisation experiments to rely on new technologies, necessary for the deployment of arrays thousands of detectors with a broad frequency coverage and operating them for extended periods of time. This increased complexity of experimental design unavoidably introduces new instrumental and systematic effects, which may impact performance of the new instruments. In this work we extend the standard data analysis pipeline by including a (parametric) model of instrumental effects directly in the data model. We then correct for them in the analysis, accounting for the additional uncertainty in the final results. We embed these techniques within a general, end-to-end formalism for estimating the impact of the instrument and foreground models on constraints on the amplitude of the primordial B-mode signal. We focus on the parametric component separation approach which we generalize to allow for simultaneous estimation of instrumental and foreground parameters. We demonstrate the framework by studying the effects induced by an achromatic half-wave plate (HWP), which lead to a frequency-dependent variation of the instrument polarisation angle, and experimental bandpasses which define observational frequency bands. We assume a typical Stage-3 CMB polarisation experiment, and show that maps recovered from raw data collected at each frequency band will unavoidably be linear mixtures of the Q and U Stokes parameters. We then derive a new generalized data model appropriate for such cases, and extend the component separation approach to account for it. We find that some of the instrumental parameters, in particularly those describing the HWP can be successfully constrained by the data themselves without need for external information, while others, like bandpasses, need to be known with good precision in advance.
{"title":"Framework for analysis of next generation, polarized CMB data sets in the presence of Galactic foregrounds and systematic effects","authors":"C. Vergès, J. Errard, R. Stompor","doi":"10.1103/PHYSREVD.103.063507","DOIUrl":"https://doi.org/10.1103/PHYSREVD.103.063507","url":null,"abstract":"Reaching the sufficient sensitivity to detect primordial B-modes requires modern CMB polarisation experiments to rely on new technologies, necessary for the deployment of arrays thousands of detectors with a broad frequency coverage and operating them for extended periods of time. This increased complexity of experimental design unavoidably introduces new instrumental and systematic effects, which may impact performance of the new instruments. In this work we extend the standard data analysis pipeline by including a (parametric) model of instrumental effects directly in the data model. We then correct for them in the analysis, accounting for the additional uncertainty in the final results. We embed these techniques within a general, end-to-end formalism for estimating the impact of the instrument and foreground models on constraints on the amplitude of the primordial B-mode signal. We focus on the parametric component separation approach which we generalize to allow for simultaneous estimation of instrumental and foreground parameters. \u0000We demonstrate the framework by studying the effects induced by an achromatic half-wave plate (HWP), which lead to a frequency-dependent variation of the instrument polarisation angle, and experimental bandpasses which define observational frequency bands. We assume a typical Stage-3 CMB polarisation experiment, and show that maps recovered from raw data collected at each frequency band will unavoidably be linear mixtures of the Q and U Stokes parameters. We then derive a new generalized data model appropriate for such cases, and extend the component separation approach to account for it. We find that some of the instrumental parameters, in particularly those describing the HWP can be successfully constrained by the data themselves without need for external information, while others, like bandpasses, need to be known with good precision in advance.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82167712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Schrabback, S. Bocquet, M. Sommer, H. Zohren, J. L. V. D. Busch, B. Hernandez-Martin, H. Hoekstra, S. Raihan, M. Schirmer, D. Applegate, M. Bayliss, B. Benson, L. Bleem, J. Dietrich, B. Floyd, S. Hilbert, J. Hlavacek-Larrondo, M. Mcdonald, A. Saro, A. Stark, N. Weissgerber
Expanding from previous work we present weak lensing measurements for a total sample of 30 distant ($z_mathrm{median}=0.93$) massive galaxy clusters from the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) Survey, measuring galaxy shapes in Hubble Space Telescope (HST) Advanced Camera for Surveys images. We remove cluster members and preferentially select $zgtrsim 1.4$ background galaxies via $V-I$ colour, employing deep photometry from VLT/FORS2 and Gemini-South/GMOS. We apply revised calibrations for the weak lensing shape measurements and the source redshift distribution to estimate the cluster masses. In combination with earlier Magellan/Megacam results for lower-redshifts clusters we infer refined constraints on the scaling relation between the SZ detection significance and the cluster mass, in particular regarding its redshift evolution. The mass scale inferred from the weak lensing data is lower by a factor $0.76^{+0.10}_{-0.14}$ (at our pivot redshift $z=0.6$) compared to what would be needed to reconcile a Planck $nuLambda$CDM cosmology with the observed SPT-SZ cluster counts. In order to sensitively test the level of (dis-)agreement between SPT clusters and Planck, further expanded weak lensing follow-up samples are needed.
{"title":"Mass calibration of distant SPT galaxy clusters through expanded weak-lensing follow-up observations with HST, VLT, & Gemini-South","authors":"T. Schrabback, S. Bocquet, M. Sommer, H. Zohren, J. L. V. D. Busch, B. Hernandez-Martin, H. Hoekstra, S. Raihan, M. Schirmer, D. Applegate, M. Bayliss, B. Benson, L. Bleem, J. Dietrich, B. Floyd, S. Hilbert, J. Hlavacek-Larrondo, M. Mcdonald, A. Saro, A. Stark, N. Weissgerber","doi":"10.1093/mnras/stab1386","DOIUrl":"https://doi.org/10.1093/mnras/stab1386","url":null,"abstract":"Expanding from previous work we present weak lensing measurements for a total sample of 30 distant ($z_mathrm{median}=0.93$) massive galaxy clusters from the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) Survey, measuring galaxy shapes in Hubble Space Telescope (HST) Advanced Camera for Surveys images. We remove cluster members and preferentially select $zgtrsim 1.4$ background galaxies via $V-I$ colour, employing deep photometry from VLT/FORS2 and Gemini-South/GMOS. We apply revised calibrations for the weak lensing shape measurements and the source redshift distribution to estimate the cluster masses. In combination with earlier Magellan/Megacam results for lower-redshifts clusters we infer refined constraints on the scaling relation between the SZ detection significance and the cluster mass, in particular regarding its redshift evolution. The mass scale inferred from the weak lensing data is lower by a factor $0.76^{+0.10}_{-0.14}$ (at our pivot redshift $z=0.6$) compared to what would be needed to reconcile a Planck $nuLambda$CDM cosmology with the observed SPT-SZ cluster counts. In order to sensitively test the level of (dis-)agreement between SPT clusters and Planck, further expanded weak lensing follow-up samples are needed.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90999600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-14DOI: 10.1103/physrevd.102.123545
L. Thiele, J. Hill, Kendrick M. Smith
The one-point probability distribution function (PDF) is a powerful summary statistic for non-Gaussian cosmological fields, such as the weak lensing (WL) convergence reconstructed from galaxy shapes or cosmic microwave background maps. Thus far, no analytic model has been developed that successfully describes the high-convergence tail of the WL convergence PDF for small smoothing scales from first principles. Here, we present a halo-model formalism to compute the WL convergence PDF, building upon our previous results for the thermal Sunyaev-Zel'dovich field. Furthermore, we extend our formalism to analytically compute the covariance matrix of the convergence PDF. Comparisons to numerical simulations generally confirm the validity of our formalism in the non-Gaussian, positive tail of the WL convergence PDF, but also reveal the convergence PDF's strong sensitivity to small-scale systematic effects in the simulations (e.g., due to finite resolution). Finally, we present a simple Fisher forecast for a Rubin Observatory-like survey, based on our new analytic model. Considering the ${A_s, Omega_m, Sigma m_nu}$ parameter space and assuming a Planck CMB prior on $A_s$ only, we forecast a marginalized constraint $sigma(Sigma m_nu) approx 0.08$ eV from the WL convergence PDF alone, even after marginalizing over parameters describing the halo concentration-mass relation. This error bar on the neutrino mass sum is comparable to the minimum value allowed in the normal hierarchy, illustrating the strong constraining power of the WL convergence PDF. We make our code publicly available at this https URL.
{"title":"Accurate analytic model for the weak lensing convergence one-point probability distribution function and its autocovariance","authors":"L. Thiele, J. Hill, Kendrick M. Smith","doi":"10.1103/physrevd.102.123545","DOIUrl":"https://doi.org/10.1103/physrevd.102.123545","url":null,"abstract":"The one-point probability distribution function (PDF) is a powerful summary statistic for non-Gaussian cosmological fields, such as the weak lensing (WL) convergence reconstructed from galaxy shapes or cosmic microwave background maps. Thus far, no analytic model has been developed that successfully describes the high-convergence tail of the WL convergence PDF for small smoothing scales from first principles. Here, we present a halo-model formalism to compute the WL convergence PDF, building upon our previous results for the thermal Sunyaev-Zel'dovich field. Furthermore, we extend our formalism to analytically compute the covariance matrix of the convergence PDF. Comparisons to numerical simulations generally confirm the validity of our formalism in the non-Gaussian, positive tail of the WL convergence PDF, but also reveal the convergence PDF's strong sensitivity to small-scale systematic effects in the simulations (e.g., due to finite resolution). Finally, we present a simple Fisher forecast for a Rubin Observatory-like survey, based on our new analytic model. Considering the ${A_s, Omega_m, Sigma m_nu}$ parameter space and assuming a Planck CMB prior on $A_s$ only, we forecast a marginalized constraint $sigma(Sigma m_nu) approx 0.08$ eV from the WL convergence PDF alone, even after marginalizing over parameters describing the halo concentration-mass relation. This error bar on the neutrino mass sum is comparable to the minimum value allowed in the normal hierarchy, illustrating the strong constraining power of the WL convergence PDF. We make our code publicly available at this https URL.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"34 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75794437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Contarini, F. Marulli, L. Moscardini, A. Veropalumbo, C. Giocoli, M. Baldi
Cosmic voids are progressively emerging as a new viable cosmological probe. Their abundance and density profiles are sensitive to modifications of gravity, as well as to dark energy and neutrinos. The main goal of this work is to investigate the possibility of exploiting cosmic void statistics to disentangle the degeneracies resulting from a proper combination of $f(R)$ modified gravity and neutrino mass. We use large N-body simulations to analyse the density profiles and size function of voids traced by both dark matter particles and haloes. We find clear evidence of the enhancement of gravity in $f(R)$ cosmologies in the void density profiles at $z=1$. However, these effects can be almost completely overridden by the presence of massive neutrinos because of their thermal free-streaming. On the other hand, we find that the void size function at high redshifts and for large voids is an effective probe to disentangle these degenerate cosmological models, which is key in the prospective of the upcoming wide field redshift surveys.
{"title":"Cosmic voids in modified gravity models with massive neutrinos","authors":"S. Contarini, F. Marulli, L. Moscardini, A. Veropalumbo, C. Giocoli, M. Baldi","doi":"10.1093/mnras/stab1112","DOIUrl":"https://doi.org/10.1093/mnras/stab1112","url":null,"abstract":"Cosmic voids are progressively emerging as a new viable cosmological probe. Their abundance and density profiles are sensitive to modifications of gravity, as well as to dark energy and neutrinos. The main goal of this work is to investigate the possibility of exploiting cosmic void statistics to disentangle the degeneracies resulting from a proper combination of $f(R)$ modified gravity and neutrino mass. We use large N-body simulations to analyse the density profiles and size function of voids traced by both dark matter particles and haloes. We find clear evidence of the enhancement of gravity in $f(R)$ cosmologies in the void density profiles at $z=1$. However, these effects can be almost completely overridden by the presence of massive neutrinos because of their thermal free-streaming. On the other hand, we find that the void size function at high redshifts and for large voids is an effective probe to disentangle these degenerate cosmological models, which is key in the prospective of the upcoming wide field redshift surveys.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87197874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-07DOI: 10.1103/PhysRevD.103.123508
The Gambit Cosmology Workgroup Patrick Stocker, C. Bal'azs, Sanjay Bloor, T. Bringmann, T. Gonzalo, Will Handley, Selim Hotinli, C. Howlett, F. Kahlhoefer, Janina J. Renk, P. Scott, A. Vincent, M. White
We determine the upper limit on the mass of the lightest neutrino from the most robust recent cosmological and terrestrial data. Marginalising over possible effective relativistic degrees of freedom at early times ($N_mathrm{eff}$) and assuming normal mass ordering, the mass of the lightest neutrino is less than 0.037 eV at 95% confidence; with inverted ordering, the bound is 0.042 eV. This improves nearly 60% on other recent limits, bounding the mass of the lightest neutrino to be barely larger than the largest mass splitting. We show the impacts of realistic mass models, and different sources of $N_mathrm{eff}$.
{"title":"Strengthening the bound on the mass of the lightest neutrino with terrestrial and cosmological experiments","authors":"The Gambit Cosmology Workgroup Patrick Stocker, C. Bal'azs, Sanjay Bloor, T. Bringmann, T. Gonzalo, Will Handley, Selim Hotinli, C. Howlett, F. Kahlhoefer, Janina J. Renk, P. Scott, A. Vincent, M. White","doi":"10.1103/PhysRevD.103.123508","DOIUrl":"https://doi.org/10.1103/PhysRevD.103.123508","url":null,"abstract":"We determine the upper limit on the mass of the lightest neutrino from the most robust recent cosmological and terrestrial data. Marginalising over possible effective relativistic degrees of freedom at early times ($N_mathrm{eff}$) and assuming normal mass ordering, the mass of the lightest neutrino is less than 0.037 eV at 95% confidence; with inverted ordering, the bound is 0.042 eV. This improves nearly 60% on other recent limits, bounding the mass of the lightest neutrino to be barely larger than the largest mass splitting. We show the impacts of realistic mass models, and different sources of $N_mathrm{eff}$.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81172879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Guandalin, J. Adamek, P. Bull, C. Clarkson, L. Abramo, Louis Coates
Planned efforts to probe the largest observable distance scales in future cosmological surveys are motivated by a desire to detect relic correlations left over from inflation, and the possibility of constraining novel gravitational phenomena beyond General Relativity (GR). On such large scales, the usual Newtonian approaches to modelling summary statistics like the power spectrum and bispectrum are insufficient, and we must consider a fully relativistic and gauge-independent treatment of observables such as galaxy number counts in order to avoid subtle biases, e.g. in the determination of the $f_{rm NL}$ parameter. In this work, we present an initial application of an analysis pipeline capable of accurately modelling and recovering relativistic spectra and correlation functions. As a proof of concept, we focus on the non-zero dipole of the redshift-space power spectrum that arises in the cross-correlation of different mass bins of dark matter halos, using strictly gauge-independent observable quantities evaluated on the past light cone of a fully relativistic N-body simulation in a redshift bin $1.7 le z le 2.9$. We pay particular attention to the correct estimation of power spectrum multipoles, comparing different methods of accounting for complications such as the survey geometry (window function) and evolution/bias effects on the past light cone, and discuss how our results compare with previous attempts at extracting novel GR signatures from relativistic simulations.
在未来的宇宙学调查中，计划探索最大可观测距离尺度的努力，是出于探测暴胀遗留下来的遗迹相关性的愿望，以及约束广义相对论(GR)之外的新引力现象的可能性。在如此大的尺度上，通常的牛顿方法来建模总结统计，如功率谱和双谱是不够的，我们必须考虑一个完全相对论和独立于测量的处理观测，如星系数计数，以避免微妙的偏差，例如在确定$f_{rm NL}$参数。在这项工作中，我们提出了一个能够准确建模和恢复相对论光谱和相关函数的分析管道的初步应用。作为概念证明，我们重点研究了在暗物质晕的不同质量仓相互关联中产生的红移空间功率谱的非零偶极子，使用严格独立于量规的可观测量在红移仓$1.7 le z le 2.9$的完全相对论n体模拟的过去光锥上进行评估。我们特别关注功率谱多极的正确估计，比较了计算复杂性的不同方法，如测量几何形状(窗函数)和过去光锥的演化/偏差效应，并讨论了我们的结果如何与之前从相对论模拟中提取新GR特征的尝试进行比较。
{"title":"Observing relativistic features in large-scale structure surveys – I. Multipoles of the power spectrum","authors":"C. Guandalin, J. Adamek, P. Bull, C. Clarkson, L. Abramo, Louis Coates","doi":"10.1093/mnras/staa3890","DOIUrl":"https://doi.org/10.1093/mnras/staa3890","url":null,"abstract":"Planned efforts to probe the largest observable distance scales in future cosmological surveys are motivated by a desire to detect relic correlations left over from inflation, and the possibility of constraining novel gravitational phenomena beyond General Relativity (GR). On such large scales, the usual Newtonian approaches to modelling summary statistics like the power spectrum and bispectrum are insufficient, and we must consider a fully relativistic and gauge-independent treatment of observables such as galaxy number counts in order to avoid subtle biases, e.g. in the determination of the $f_{rm NL}$ parameter. In this work, we present an initial application of an analysis pipeline capable of accurately modelling and recovering relativistic spectra and correlation functions. As a proof of concept, we focus on the non-zero dipole of the redshift-space power spectrum that arises in the cross-correlation of different mass bins of dark matter halos, using strictly gauge-independent observable quantities evaluated on the past light cone of a fully relativistic N-body simulation in a redshift bin $1.7 le z le 2.9$. We pay particular attention to the correct estimation of power spectrum multipoles, comparing different methods of accounting for complications such as the survey geometry (window function) and evolution/bias effects on the past light cone, and discuss how our results compare with previous attempts at extracting novel GR signatures from relativistic simulations.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"78 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80246696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We explore the implications of a single observer's viewpoint on measurements of galaxy clustering statistics. We focus on the Bardeen potentials, which imprint characteristic scale-dependent signatures in the observed galaxy power spectrum. The existence of an observer breaks homogeneity as it singles out particular field values at her/his position, like a spontaneous symmetry breaking. As a result, spatial averaging of the data must be performed while holding the Bardeen potentials fixed at the observer's position. In practice, this can be implemented with the formalism of constrained random fields. In the traditional Cartesian Fourier decomposition, this constraint imprints a signature in the observed galaxy power spectrum at wavenumbers comparable to the fundamental mode of the survey. For typical fluctuations however, this effect is within the cosmic variance. In a spherical Bessel Fourier decomposition, this constraint affects the monopole of the observed galaxy distribution solely, like in CMB data. As a corollary, the scale-dependence of the non-Gaussian bias induced by a local primordial non-Gaussianity is not significantly affected by the observer's viewpoint.
{"title":"Statistics of a single sky: constrained random fields and the imprint of Bardeen potentials on galaxy clustering","authors":"V. Desjacques, Yonadav Barry Ginat, R. Reischke","doi":"10.1093/mnras/stab1228","DOIUrl":"https://doi.org/10.1093/mnras/stab1228","url":null,"abstract":"We explore the implications of a single observer's viewpoint on measurements of galaxy clustering statistics. We focus on the Bardeen potentials, which imprint characteristic scale-dependent signatures in the observed galaxy power spectrum. The existence of an observer breaks homogeneity as it singles out particular field values at her/his position, like a spontaneous symmetry breaking. As a result, spatial averaging of the data must be performed while holding the Bardeen potentials fixed at the observer's position. In practice, this can be implemented with the formalism of constrained random fields. In the traditional Cartesian Fourier decomposition, this constraint imprints a signature in the observed galaxy power spectrum at wavenumbers comparable to the fundamental mode of the survey. For typical fluctuations however, this effect is within the cosmic variance. In a spherical Bessel Fourier decomposition, this constraint affects the monopole of the observed galaxy distribution solely, like in CMB data. As a corollary, the scale-dependence of the non-Gaussian bias induced by a local primordial non-Gaussianity is not significantly affected by the observer's viewpoint.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80621682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1103/physrevd.102.123521
D. Wadekar, M. Ivanov, R. Scoccimarro
We use analytic covariance matrices to carry out a full-shape analysis of the galaxy power spectrum multipoles from the Baryon Oscillation Spectroscopic Survey (BOSS). We obtain parameter estimates that agree well with those based on the sample covariance from two thousand galaxy mock catalogs, thus validating the analytic approach and providing substantial reduction in computational cost. We also highlight a number of additional advantages of analytic covariances. First, the analysis does not suffer from sampling noise, which biases the constraints and typically requires inflating parameter error bars. Second, it allows us to study convergence of the cosmological constraints when recomputing the analytic covariances to match the best-fit power spectrum, which can be done at a negligible computational cost, unlike when using mock catalogs. These effects reduce the systematic error budget of cosmological constraints, which suggests that the analytic approach may be an important tool for upcoming high-precision galaxy redshift surveys such as DESI and Euclid. Finally, we study the impact of various ingredients in the power spectrum covariance matrix and show that the non-Gaussian part, which includes the regular trispectrum and super-sample covariance, has a marginal effect ($lesssim 10 %$) on the cosmological parameter error bars. We also suggest improvements to analytic covariances that are commonly used in Fisher forecasts.
{"title":"Cosmological constraints from BOSS with analytic covariance matrices","authors":"D. Wadekar, M. Ivanov, R. Scoccimarro","doi":"10.1103/physrevd.102.123521","DOIUrl":"https://doi.org/10.1103/physrevd.102.123521","url":null,"abstract":"We use analytic covariance matrices to carry out a full-shape analysis of the galaxy power spectrum multipoles from the Baryon Oscillation Spectroscopic Survey (BOSS). We obtain parameter estimates that agree well with those based on the sample covariance from two thousand galaxy mock catalogs, thus validating the analytic approach and providing substantial reduction in computational cost. We also highlight a number of additional advantages of analytic covariances. First, the analysis does not suffer from sampling noise, which biases the constraints and typically requires inflating parameter error bars. Second, it allows us to study convergence of the cosmological constraints when recomputing the analytic covariances to match the best-fit power spectrum, which can be done at a negligible computational cost, unlike when using mock catalogs. These effects reduce the systematic error budget of cosmological constraints, which suggests that the analytic approach may be an important tool for upcoming high-precision galaxy redshift surveys such as DESI and Euclid. Finally, we study the impact of various ingredients in the power spectrum covariance matrix and show that the non-Gaussian part, which includes the regular trispectrum and super-sample covariance, has a marginal effect ($lesssim 10 %$) on the cosmological parameter error bars. We also suggest improvements to analytic covariances that are commonly used in Fisher forecasts.","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"131 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84484118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-31DOI: 10.1016/j.physletb.2021.136427
Y. Akrami, M. Sasaki, A. Solomon, V. Vardanyan
{"title":"Multi-field dark energy: Cosmic acceleration on a steep potential","authors":"Y. Akrami, M. Sasaki, A. Solomon, V. Vardanyan","doi":"10.1016/j.physletb.2021.136427","DOIUrl":"https://doi.org/10.1016/j.physletb.2021.136427","url":null,"abstract":"","PeriodicalId":8431,"journal":{"name":"arXiv: Cosmology and Nongalactic Astrophysics","volume":"176 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76635521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-26DOI: 10.1051/0004-6361/201937138
P. Bergamini, A. Agnello, G. Caminha
Lensing by galaxy clusters is a versatile probe of cosmology and extragalactic astrophysics, but the accuracy of some of its predictions is limited by the simplified models adopted to reduce the (otherwise untractable) number of degrees of freedom. We aim at cluster lensing models where the parameters of all cluster-member galaxies are free to vary around some common scaling relations with non-zero scatter, and deviate significantly from them if and only if the data require it. We have devised a Bayesian hierarchical inference framework, which enables the determination of all lensing parameters and of the scaling-relation hyperparameters, including intrinsic scatter, from lensing constraints and (if given) stellar kinematic measurements. We achieve this through BayesLens, a purpose-built wrapper around common, parametric lensing codes for the lensing likelihood and samples the posterior on parameters and hyperparameters, which we release with this paper. We have run functional tests of our code against simple mock cluster lensing datasets with realistic uncertainties. The parameters and hyperparameters are recovered within their 68% credibility ranges, and the positions of all the "observed" multiple images are accurately reproduced by the BayeLens best-fit model, without overfitting. We have shown that an accurate description of cluster member galaxies is attainable, despite the large number of degrees of freedom, through fast and tractable inference. This extends beyond the state-of-the-art of current cluster lensing models. The precise impact on studies of cosmography, galaxy evolution and high-redshift galaxy populations can then be quantified on real galaxy clusters. While other sources of systematics exist and may be significant in real clusters, our results show that the contribution of intrinsic scatter in cluster-member populations can now be controlled.
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