In the hierarchical structure formation model of the universe, galaxy clusters are assembled through a series of mergers. Accordingly, it is expected that galaxy clusters in the early universe are actively forming and dynamically young. Located at a high redshift of z=1.71, SpARCS1049+56 offers a unique look into the galaxy cluster formation process. This cluster has been shown to be rich in cluster galaxies and to have intense star formation. Its high redshift pushes a weak-lensing analysis beyond the regime of the optical spectrum into that of the infrared. Equipped with deep Hubble Space Telescope Wide Field Camera 3 UVIS and IR observations, we present a weak-lensing characterization of SpARCS1049+56. As few IR weak-lensing studies have been performed, we discuss the details of PSF modeling and galaxy shape measurement for an IR weak-lensing procedure and the systematics that come with the territory. It will be critical to understand these systematics in future weak-lensing studies in the IR with the next generation space telescopes such as JWST, Euclid, and WFIRST. Through a careful analysis, the mass distribution of this young galaxy cluster is mapped and the convergence peak is detected at a 3.3 sigma level. The weak-lensing mass of the cluster is estimated to be $3.5\pm1.2\times10^{14}\ \text{M}_\odot$ and is consistent with the mass derived from a mass-richness scaling relation. This mass is extreme for a cluster at such a high redshift and suggests that SpARCS1049+56 is rare in the standard $Λ$CDM universe.
Upcoming surveys such as \LSST{} and \Euclid{} will significantly improve the power of weak lensing as a cosmological probe. To maximise the information that can be extracted from these surveys, it is important to explore novel statistics that complement standard weak lensing statistics such as the shear-shear correlation function and peak counts. In this work, we use a recently proposed weak lensing observable -- weak lensing voids -- to make parameter constraint forecasts for an LSST-like survey. We use the \cosmoslics{} $w$CDM simulation suite to measure void statistics as a function of cos…
Next-generation galaxy surveys will be able to measure perturbations on scales beyond the equality scale. On these ultra-large scales, primordial non-Gaussianity leaves signatures that can shed light on the mechanism by which perturbations in the early Universe are generated. We perform a forecast analysis for constraining local type non-Gaussianity and its two-parameter extension with a simple scale-dependence. We combine different clustering measurements from future galaxy surveys -- a 21cm intensity mapping survey and two photometric galaxy surveys -- via the multi-tracer approach. Furtherm…
We show that peculiar velocities of Type Ia supernovae can be used to derive constraints on the sum of neutrino masses, $Σm_ν$, and dark energy equation of state, $w = w_0+w_a(1-a)$, from measurements of the magnitude-redshift relation, complementary to galaxy redshift and weak lensing surveys. Light from a supernova propagates through a perturbed Universe so the luminosity distance is modified from its homogeneous prediction. This modification is proportional to the matter density fluctuation and its time derivative due to gravitational lensing and peculiar velocity respectively. At low redsh…
The presence of massive neutrinos affects structure formation, leaving imprints on large-scale structure observables such as the weak lensing field. The common lensing analyses with two-point statistics are insensitive to the large amount of non-Gaussian information in the density field. We investigate non-Gaussian tools, in particular the Minkowski Functionals (MFs)---morphological descriptors including area, perimeter, and genus---in an attempt to recover the higher-order information. We use convergence maps from the Cosmological Massive Neutrino Simulations (\texttt{MassiveNus}) and assume …
Measuring the total neutrino mass is one of the most exciting opportunities available with next-generation cosmological data sets. We study the possibility of detecting the total neutrino mass using large-scale clustering in 21cm intensity mapping and photometric galaxy surveys, together with CMB information. We include the scale-dependent halo bias contribution due to the presence of massive neutrinos, and use a multi-tracer analysis in order to reduce cosmic variance. The multi-tracer combination of an SKAO-MID 21cm intensity map with Stage~4 CMB dramatically shrinks the uncertainty on total…
Constraining Neutrino Mass with the Void Weak Lensing Effect
Tsinghua University（清华大学）；Shanghai Astronomical Observatory (SHAO)（上海天文台）；University of Chinese Academy of Sciences（中国科学院大学）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
The possible time variation of the fundamental constants of nature has been an active subject of research since the large-number hypothesis was proposed by Dirac. In this paper, we propose a new method to investigate a possible time variation of the speed of light ($c$) along with the fine-structure constant ($α$) using Strong Gravitational Lensing (SGL) and Type Ia Supernovae (SNe Ia) observations. We assume a general approach to describe the mass distribution of lens-type galaxies, the one in favor of the power-law index model (PLAW). We also consider the runaway dilaton model to describe a …
Modern weak-lensing observations are becoming increasingly sensitive to baryonic feedback processes which are still poorly understood. So far, this challenge has been faced either by imposing scale-cuts in the data or by modelling baryonic effects with simple, one-parameter models. In this paper, we rely on a more general, seven-parameter prescription of baryonic feedback effects, which is primarily motivated by observations and has been shown to agree with a plethora of hydrodynamical simulations. By combining weak-lensing data from the Kilo-Degree Survey (KiDS-1000) with observations of gas …
Massive neutrinos influence the background evolution of the Universe as well as the growth of structure. Being able to model this effect and constrain the sum of their masses is one of the key challenges in modern cosmology. Weak-lensing cosmological constraints will also soon reach higher levels of precision with next-generation surveys like LSST, WFIRST and Euclid. We use the MassiveNus simulations to derive constraints on the sum of neutrino masses $M_ν$, the present-day total matter density $Ω_{\rm m}$, and the primordial power spectrum normalization $A_{\rm s}$ in a tomographic setting. W…
Gravitational waves (GWs) are subject to gravitational lensing in the same way as electromagnetic radiation. However, to date, no unequivocal observation of a lensed GW transient has been reported. Independently, GW observatories continue to search for the stochastic GW signal which is produced by many transient events at high redshift. We exploit a surprising connection between the lensing of individual transients and limits to the background radiation produced by the unresolved population of binary back hole mergers: we show that it constrains the fraction of individually resolvable lensed b…
Ongoing and planned weak lensing (WL) surveys are becoming deep enough to contain information on angular scales down to a few arcmin. To fully extract information from these small scales, we must capture non-Gaussian features in the cosmological WL signal while accurately accounting for baryonic effects. In this work, we account for baryonic physics via a baryonic correction model that modifies the matter distribution in dark matter-only $N$-body simulations, mimicking the effects of galaxy formation and feedback. We implement this model in a large suite of ray-tracing simulations, spanning a …
Weak lensing peak counts are a powerful statistical tool for constraining cosmological parameters. So far, this method has been applied only to surveys with relatively small areas, up to several hundred square degrees. As future surveys will provide weak lensing datasets with size of thousands of square degrees, the demand on the theoretical prediction of the peak statistics will become heightened. In particular, large simulations of increased cosmological volume are required. In this work, we investigate the possibility of using simulations generated with the fast Comoving-Lagrangian accelera…
We study the cross correlation of damped Ly$α$ systems (DLAs) and their background quasars, using the most updated DLA catalog and the Planck 2018 CMB lensing convergence field. Our measurement suggests that the DLA bias $b_{\rm DLA}$ is smaller than $3.1$, corresponding to $\log(M/M_\odot h^{-1})\leq 12.3$ at a confidence of $90\%$. These constraints are broadly consistent with Alonso et al. (2018) and previous measurements by cross-correlation between DLAs and the Ly$α$ forest (e.g. Font-Ribera et al. 2012; Perez-Rafols et al. 2018). Further, our results demonstrate the potential of obtainin…
Constraining Multiplicative Bias in CFHTLenS Weak Lensing Shear Data
最近的一些宇宙学分析发现，来自加拿大-法国-夏威夷望远镜透镜巡天（CFHTLenS）数据的约束与来自其他数据集（如普朗克宇宙微波背景（CMB）温度各向异性）的约束之间存在紧张关系。类似地，CFHTLenS数据与普朗克CMB透镜数据的直接互相关产生了与基于普朗克或WMAP导出的宇宙学参数的预期相比非常低的振幅（Liu & Hill 2015）。这些结果的一个潜在解释是影响CFHTLenS星系形状测量的乘法偏差，从中推断出剪切。CFHTLenS管道中使用模拟来校准此类偏差，但迄今为止尚未提出数据驱动的约束。在本文中，我们将CFHTLenS星系密度图与CFHTLenS剪切图和普朗克CMB透镜图进行交叉关联，以校准CFHTLenS中的额外乘法剪切偏差（m）（超出已经应用于CFHTLenS星系剪切的乘法校正），遵循Vallinotto（2012）和Das等人建议的方法。我们分析了三个星等有限的星系样本，发现使用最深的样本（i<24）的2-4sigma证据m<1，而其他的则与m=1一致（无偏差）。这与暗星系的形状最容易受到测量偏差的影响的预期相匹配。我们的结果m基本上是独立的假设宇宙学，只有弱敏感的假设星系的偏见。我们考虑三个星系的偏见模型，发现在所有情况下，最适合的乘法剪切偏置小于统一。m~0.9的值足以使从CFHTLenS剪切两点统计推断的密度波动幅度与从普朗克CMB温度数据推断的密度波动…
Strong gravitational lensing along with the distance sum rule method can constrain both cosmological parameters as well as density profiles of galaxies without assuming any fiducial cosmological model. To constrain galaxy parameters and cosmic curvature $(Ω_{k0})$, we use the distance ratio data from a recently compiled database of $161$ galactic scale strong lensing systems. We use databases of supernovae type-Ia (Pantheon) and Gamma Ray Bursts (GRBs) for calculating the luminosity distance. To study the model of the lens galaxy, we consider a general lens model namely, the Extended Power-Law…
Gravitational lensing has long been used to measure or constrain cosmology models. Although the lensing effect of gravitational waves has not been observed by LIGO/Virgo, it is expected that there can be a few to a few hundreds lensed events to be detected by the future Japanese space-borne interferometers DECIGO and B-DECIGO, if they are running for 4 years. Given the predicted lensed gravitational wave events, one can estimate the constraints on the cosmological parameters via the lensing statistics and the time delay methods. With the lensing statistics method, the knowledge of the lens red…
We quantify the cosmological constraining power of the `lensing PDF' - the one-point probability density of weak lensing convergence maps - by modelling this statistic numerically with an emulator trained on $w$CDM cosmic shear simulations. After validating our methods on Gaussian and lognormal fields, we show that `multi-scale' PDFs - measured from maps with multiple levels of smoothing - offer considerable gains over two-point statistics, owing to their ability to extract non-Gaussian information: for a mock Stage-III survey, lensing PDFs yield 33\% tighter constraints on the clustering para…
We demonstrate the utility and constraining power of a new statistic for investigating galaxy bias: the galaxy-lensing phase difference. The statistic consists in taking the differences of the phases of the harmonic wave-modes between the weak lensing convergence field and the galaxy count field. We use dark matter simulations populated with galaxies up to redshift $z=1$ to test the performance of this estimator. We find that phase differences are sensitive to the absolute value of the second order bias ($c_2=b_2/b_1$), and demonstrate why this is the case. For a $\sim$1500 sq. deg. galaxy sur…
We investigate cosmological parameter inference from realistic simulated weak lensing image data using only galaxy position angles, as opposed to full-ellipticity information. We demonstrate that input shear fields can be accurately reconstructed using only the statistics of source galaxy position angles and that, from these shear fields, we can successfully recover power spectra and infer the input cosmology. This paper builds on previous work on angle-only weak lensing estimation by extending the method to deal with variable and anisotropic PSF convolution and variable shear fields. Previous…
Strongly gravitational lensing systems (SGL) encodes cosmology information in source/lens distance ratios $\mathcal{D}_{\rm obs}=\mathcal{D}_{\rm ls}/\mathcal{D}_{\rm s}$, which can be used to precisely constrain cosmological parameters. In this paper, based on future measurements of 390 strong lensing systems from the forthcoming LSST survey, we have successfully reconstructed the distance ratio $\mathcal{D}_{\rm obs}$ (with the source redshift $z_s\sim 4.0$), directly from the data without assuming any parametric form. A recently developed method based on model-independent reconstruction app…
Galaxy cluster mergers are a powerful laboratory for testing cosmological and astrophysical models. However, interpreting individual merging clusters depends crucially on their merger configuration, defined by the masses, velocities, impact parameters, and orientation of the merger axis with respect to the plane of the sky. In this work, we investigate the impact of merger parameters on the X-ray emitting intracluster medium and gravitational lensing maps using a suite of idealised simulations of binary cluster mergers performed using the GAMER-2 code. As a test case, we focus on modeling the …
We measure the harmonic-space auto-power spectrum of the galaxy overdensity in the LOFAR Two-metre Sky Survey (LoTSS) First Data Release and its cross correlation with the map of the lensing convergence of the cosmic microwave background (CMB) from the Planck collaboration. We report a $\sim5σ$ detection of the cross-correlation. We show that the combination of the clustering power spectrum and CMB lensing cross-correlation allows us to place constraints on the high-redshift tail of the redshift distribution, one of the largest sources of uncertainty in the use of continuum surveys for cosmolo…
We investigate the prospects of detecting the cross correlation of CMBR weak-lensing convergence field with the large scale tracers of the underlying dark matter distribution in the post-reionization epoch. The cross-correlation is then used to make error projections for dark energy equation of state (EoS)for models with a time evolving dark energy. We study the cross-correlation angular power spectrum of the weak-lensing field with the Lyman-$α$ forest and the redshifted HI 21 cm signal from the post reionization epoch. The angular power spectra is expressed as a line of sight average over th…
This paper aims to perform a phenomenological parametrisation of the standard cosmological model, $Λ$CDM, to weigh the different physical processes that define the pattern of the angular power spectra of the Cosmic Microwave Background (CMB) anisotropies. We use six phenomenological amplitudes to account for the Sachs-Wolfe, early and late Integrated Sachs-Wolfe, polarization contribution, Doppler and lensing effects. To do so, we have adapted the CLASS Boltzmann code and used the Markov Chain Monte Carlo (MCMC) sampler of Cobaya to explore the Planck 2018 likelihood to constrain different com…
