The small-scale cosmic microwave background (CMB) is dominated by anisotropies from the kinematic Sunyaev-Zeldovich (kSZ) effect, and upcoming experiments will measure it very precisely, but the optical depth degeneracy limits the cosmological information that can be extracted. At the same time, fast radio bursts (FRBs) are an exciting new frontier for astrophysics, but their usefulness as cosmological probes is currently unclear. We show that FRBs are uniquely suited for breaking the kSZ optical depth degeneracy. This opens up new possibilities for constraining cosmology with the kSZ effect, and new cosmological applications for FRBs.
The epoch of reionization is one of the major phase transitions in the history of the universe, and is a focus of ongoing and upcoming cosmic microwave background (CMB) experiments with improved sensitivity to small-scale fluctuations. Reionization also represents a significant contaminant to CMB-derived cosmological parameter constraints, due to the degeneracy between the Thomson-scattering optical depth, $τ$, and the amplitude of scalar perturbations, $A_s$. This degeneracy subsequently hinders the ability of large-scale structure data to constrain the sum of the neutrino masses, a major tar…
Toward Precision Kinetic Sunyaev-Zel'dovich Cosmology---1. The Matter - Momentum Bispectrum at One-Loop Order
Massachusetts Institute of Technology（麻省理工学院）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；Center for Theoretical Physics – a Leinweber Institute, Massachusetts Institute of Technology（麻省理工学院莱因韦伯理论物理中心）
The apparent accelerating expansion of the Universe, determined from observations of distant supernovae, and often taken to imply the existence of dark energy, may alternatively be explained by the effects of a giant underdense void if we relax the assumption of homogeneity on large scales. Recent studies have made use of the spherically-symmetric, radially-inhomogeneous Lemaitre-Tolman-Bondi (LTB) models to derive strong constraints on this scenario, particularly from observations of the kinematic Sunyaev-Zel'dovich (kSZ) effect which is sensitive to large scale inhomogeneity. However, most o…
We prove from the modified gravity (MG) galaxy/halo mock catalogs that the shape of the pairwise kinematic Sunyaev-Zeldovich (kSZ) power spectrum $P_{\rm kSZ}$ has constraining power on discriminating different gravity theories on cosmological scales. By varying the effective optical depth $τ_{\rm T}$ as a free parameter, we verify that the $τ_{\rm T}$-$f$ (the linear growth rate) degeneracy in the linear theory of $P_{\rm kSZ}$ is broken down by the non-linear structure growth and the scale-dependence of $f$ in some MG theories. Equivalently speaking, the shape of $P_{\rm kSZ}$ alone could be…
Compton scattering of the cosmic microwave background (CMB) from hot ionized gas produces a range of effects, and the leading order effects are the kinetic and thermal Sunyaev Zel'dovich (kSZ and tSZ) effects. In the near future, CMB surveys will provide the precision to probe beyond the leading order effects. In this work we study the cosmological information content of the next order term which combines the tSZ and kSZ effects, hereafter called the thermal-kinetic Sunyaev Zel'dovich (tkSZ) effect. As the tkSZ effect has the same velocity dependence as the kSZ effect, it will also have many o…
Velocity fields can be reconstructed at cosmological scales from their influence on the correlation between the cosmic microwave background and large-scale structure. Effects that induce such correlations include the kinetic Sunyaev Zel'dovich (kSZ) effect and the moving-lens effect, both of which will be measured to high precision with upcoming cosmology experiments. Galaxy measurements also provide a window into measuring velocities from the effect of redshift-space distortions (RSDs). The information that can be accessed from the kSZ or RSDs, however, is limited by astrophysical uncertainti…
We identify a new cosmological signal, the Doppler-boosted Cosmic Infrared Background (DB-CIB), arising from the peculiar motion of the galaxies whose thermal dust emission source the cosmic infrared background (CIB). This new observable is an independent probe of the cosmic velocity field, highly analogous to the well-known kinematic Sunyaev-Zel'dovich (kSZ) effect. Interestingly, DB-CIB does not suffer from the 'kSZ optical depth degeneracy', making it immune from the complex astrophysics of galaxy formation. We forecast that the DB-CIB effect is detectable in the cross-correlation of CCAT-P…
We study the potential of the kinematic SZ effect as a probe for cosmology, focusing on the pairwise method. The main challenge is disentangling the cosmologically interesting mean pairwise velocity from the cluster optical depth and the associated uncertainties on the baryonic physics in clusters. Furthermore, the pairwise kSZ signal might be affected by internal cluster motions or correlations between velocity and optical depth. We investigate these effects using the Magneticum cosmological hydrodynamical simulations, one of the largest simulations of this kind performed to date. We produce …
Future ground-based CMB experiments will generate competitive large-scale structure datasets by precisely characterizing CMB secondary anisotropies over a large fraction of the sky. We describe a method for constraining the growth rate of structure to sub-1% precision out to $z\approx 1$, using a combination of galaxy cluster peculiar velocities measured using the kinetic Sunyaev-Zel'dovich (kSZ) effect, and the velocity field reconstructed from galaxy redshift surveys. We consider only thermal SZ-selected cluster samples, which will consist of $\mathcal{O}(10^4-10^5)$ sources for Stage 3 and …
The study of neutrinos in astrophysics requires the combination of different observational probes. The temperature anisotropies of the cosmic microwave background induced via the kinematic Sunyaev-Zel'dovich (kSZ) effect may provide interesting information since they are expected to receive significant contribution from high-redshift plasma. We present a set of cosmological hydrodynamical simulations that include a treatment of the neutrino component considering four different sum of neutrino masses: $Σm_ν=(0,0.15,0.3,0.6)$ eV. Using their outputs, we modelled the kSZ effect due to the large-s…
General relativity predicts that the rotational momentum flux of matter twists the spacetime via a vector gravitomagnetic (frame-dragging) field, which remains undetected in cosmology. This vector field induces an additional gravitational lensing effect; at the same time, the momentum field sources the kinetic Sunyaev-Zel'dovich (kSZ) effect. The common origin of these two effects allows us to probe the gravitomagnetic signal via their cross-correlations. In this paper, we explore the possibility of detecting the gravitomagnetic field in $Λ$CDM by cross-correlating the weak-lensing convergence…
Estimation and mitigation of foregrounds in projected kSZ velocity reconstruction
University of Cambridge（剑桥大学）；Kavli Institute for Cosmology Cambridge（卡弗里宇宙学剑桥研究所）；Berkeley Center for Cosmological Physics, Department of Physics, University of California, Berkeley（加州大学伯克利分校物理系宇宙学物理中心）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）
The recent emergence of detections of the kinetic Sunyaev-Zel'dovich (kSZ) effect through cross-correlation techniques is encouraging for the prospects of future cosmic microwave background (CMB) experiments. Extracting information on the large-scale velocity fields and constraining cosmological parameters from such kSZ measurements requires an understanding of the optical depth to CMB photons through halos. Using cosmological hydrodynamic simulations we find that there exists a low-scatter relation between the optical depth and thermal Sunyaev-Zel'dovich (tSZ) signal of halos within a physica…
We present a 5.4$σ$ detection of the pairwise kinematic Sunyaev-Zel'dovich (kSZ) effect using Atacama Cosmology Telescope (ACT) and $\it{Planck}$ CMB observations in combination with Luminous Red Galaxy samples from the Sloan Digital Sky Survey (SDSS) DR15 catalog. Results are obtained using three ACT CMB maps: co-added 150 GHz and 98 GHz maps, combining observations from 2008-2018 (ACT DR5), which overlap with SDSS DR15 over 3,700 sq. deg., and a component-separated map using night-time only observations from 2014-2015 (ACT DR4), overlapping with SDSS DR15 over 2,089 sq. deg. Comparisons of t…
The kinematic Sunyaev-Zel'dovich (kSZ) effect --- the Doppler boosting of cosmic microwave background (CMB) photons due to Compton-scattering off free electrons with non-zero bulk velocity --- probes the abundance and distribution of baryons in the Universe. All kSZ measurements to date have explicitly required spectroscopic redshifts. Here, we implement a novel estimator for the kSZ -- large-scale structure cross-correlation based on projected fields: it does not require redshift estimates for individual objects, allowing kSZ measurements from large-scale imaging surveys. We apply this estima…
The pairwise kinematic Sunyaev-Zel'dovich (kSZ) signal from galaxy clusters is a probe of their line-of-sight momenta, and thus a potentially valuable source of cosmological information. In addition to the momenta, the amplitude of the measured signal depends on the properties of the intra-cluster gas and observational limitations such as errors in determining cluster centers and redshifts. In this work we simulate the pairwise kSZ signal of clusters at z<1, using the output from a cosmological N-body simulation and including the properties of the intra-cluster gas via a model that can be vari…
The Copernican principle, a cornerstone of modern cosmology, remains largely unproven at Gpc radial scale and above. Here we will show that, violations of this type will inevitably cause a first order anisotropic kinetic Sunyaev Zel'dovich (kSZ) effect. If large scale radial inhomogeneities have amplitude large enough to explain the "dark energy" phenomena, the induced kSZ power spectrum will be much larger than the ACT/SPT upper limit. This single test confirms the Copernican principle and rules out the adiabatic void model as a viable alternative to dark energy.
The Atacama Cosmology Telescope: A Test of the Gravitational Force Law on Cosmological Scales Using the Kinematic Sunyaev-Zeldovich Effect
University of Pennsylvania（宾夕法尼亚大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理研究所）；University of Southern California（南加州大学）；Columbia University（哥伦比亚大学）；Stanford University（斯坦福大学）；Simons Society of Fellows, Simons Foundation（西蒙斯基金会西蒙斯学者协会）；Cornell University（康奈尔大学）；Sapienza University of Rome（罗马第一大学）；Cardiff University（卡迪夫大学）；University of California, Riverside（加州大学河滨分校）；Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学物理学院天体物理研究所）；Centro de Astro-Ingeniería, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学天文工程中心）
We present the mean pairwise momentum of clusters, as observed through the kinematic Sunvaev-Zel'dovich (kSZ) effect, as a novel probe of massive neutrinos. We find that kSZ measurements with current and upcoming surveys will provide complementary constraints on the sum of neutrino masses from large scale structure and will improve on Planck satellite measurements of the primordial cosmic microwave background (CMB) and CMB lensing. Central to the constraints is a distinctive scale dependency of the kSZ neutrino signature on the mean pairwise momentum of clusters that we do not expect to be mir…
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 …
We present high signal-to-noise measurements (up to 12$σ$) of the average thermal Sunyaev Zel'dovich (tSZ) effect from optically selected galaxy groups and clusters and estimate their baryon content within a 2.1$^\prime$ radius aperture. Sources from the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey (BOSS) DR15 catalog overlap with 3,700 sq. deg. of sky observed by the Atacama Cosmology Telescope (ACT) from 2008 to 2018 at 150 and 98 GHz (ACT DR5), and 2,089 sq. deg. of internal linear combination component-separated maps combining ACT and $\it{Planck}$ data (ACT DR4)…
The thermal and kinematic Sunyaev-Zel'dovich effects (tSZ, kSZ) probe the thermodynamic properties of the circumgalactic and intracluster medium (CGM and ICM) of galaxies, groups, and clusters, since they are proportional, respectively, to the integrated electron pressure and momentum along the line-of-sight. We present constraints on the gas thermodynamics of CMASS galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) using new measurements of the kSZ and tSZ signals obtained in a companion paper. Combining kSZ and tSZ measurements, we measure within our model the amplitude of energy…
Recent results of ground-based telescopes, giving high-quality measurements of the CMB temperature power spectrum on small scales motivate the need for an accurate model of foregrounds, which dominate the primary signal at these multipoles. In a previous work, we have shown that cosmological information could be retrieved from the power spectrum of the thermal SZ effect. In this work, we introduce a physically motivated model of the Epoch of Reionisation in the cosmological analysis of CMB data, which is coherent on all scales. In particular, at high multipoles, the power spectrum of the kinet…
Future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev-Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth ($τ$) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on $τ$ are necessary. In this work, we prese…
The scattering of cosmic microwave background (CMB) photons off the free-electron gas in galaxies and clusters leaves detectable imprints on high resolution CMB maps: the thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ respectively). We use combined microwave maps from the Atacama Cosmology Telescope (ACT) DR5 and Planck in combination with the CMASS and LOWZ galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and DR12), to study the gas associated with these galaxy groups. Using individual reconstructed velocities, we perform a stacking analysis and rejec…
We use microwave temperature maps from two seasons of data from the Atacama Cosmology Telescope (ACTPol) at 146 GHz, together with the Constant Mass CMASS galaxy sample from the Baryon Oscillation Spectroscopic Survey to measure the kinematic Sunyaev-Zeľdovich (kSZ) effect over the redshift range z = 0.4 - 0.7. We use galaxy positions and the continuity equation to obtain a reconstruction of the line-of-sight velocity field. We stack the cosmic microwave background temperature at the location of each halo, weighted by the corresponding reconstructed velocity. The resulting best fit kSZ model i…
Perhaps the most controversial idea in modern cosmology is that our observable universe is contained within one bubble among many, all inhabiting the eternally inflating multiverse. One of the few way to test this idea is to look for evidence of the relic inhomogeneities left by the collisions between other bubbles and our own. Such relic inhomogeneities induces a coherent bulk flow over gigaparsec scales. Therefore, bubble collisions leave unique imprints in the cosmic microwave background (CMB) through the kinetic Sunyaev Zel'dovich (kSZ) effect, temperature anisotropies induced by the scatt…
Measurements of the kinetic Sunyaev-Zel'dovich (kSZ) effect from instruments such as the South Pole Telescope (SPT) and the Atacama Cosmology Telescope (ACT) will soon put improved constraints on reionization. Popular models assume that UV photons alone are responsible for reionization of the intergalactic medium. We explore the effects of a significant contribution of X-rays to reionization on the kSZ signal. Because X-rays have a large mean free path through the neutral intergalactic medium, they introduce partial ionization in between the sharp-edged bubbles created by UV photons. This smoo…
Breaking the Mass-sheet Degeneracy in Time-delay Cosmology with Lensed and Unlensed Type Ia Supernovae
College of Physics, Hebei Normal University（河北师范大学物理学院）；Shijiazhuang Key Laboratory of Astronomy and Space Science, Hebei Normal University（河北师范大学石家庄天文与空间科学重点实验室）；School of Physics and Technology, Wuhan University（武汉大学物理科学与技术学院）
Detection of the Pairwise Kinematic Sunyaev-Zel'dovich Effect and Pairwise Velocity with DESI DR1 Galaxies and ACT DR6 and Planck CMB Data
Cornell University（康奈尔大学）；University of Pennsylvania（宾夕法尼亚大学）；Duke University（杜克大学）；Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK（剑桥大学天文研究所）；Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge, CB3 0HA, UK（卡弗里宇宙学剑桥研究所）；Ludwig-Maximilians-Universität（慕尼黑大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）；Università degli Studi di Milano（米兰大学）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
Uncertain feedback processes in galaxies affect the distribution of matter, currently limiting the power of weak lensing surveys. If we can identify cosmological statistics that are robust against these uncertainties, or constrain these effects by other means, then we can enhance the power of current and upcoming observations from weak lensing surveys such as DES, Euclid, the Rubin Observatory, and the Roman Space Telescope. In this work, we investigate the potential of the electron density auto-power spectrum as a robust probe of cosmology and baryonic feedback. We use a suite of (magneto-)hy…
First Cosmological Constraints from the Joint Analysis of Galaxy Clustering and the Kinetic Sunyaev-Zel'dovich Effect
School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）；CSST Science Center for the Guangdong–Hong Kong–Macau Greater Bay Area, SYSU（中山大学深空巡天科学中心）
Patchy reionization leaves a number of imprints on the small-scale cosmic microwave background (CMB) temperature fluctuations, the largest of which is the kinematic Sunyaev-Zel'dovich (kSZ), the Doppler shift of CMB photons scattering off moving electrons in ionized bubbles. It has long been known that in the CMB power spectrum, this imprint of reionization is largely degenerate with the kSZ signal produced by late-time galaxies and clusters, thus limiting our ability to constrain reionization. Following Smith & Ferraro (2017), it is possible to isolate the reionization contribution in a model…
Measuring cosmic bulk flow with kinetic Sunyaev-Zel'dovich velocity reconstruction
Perimeter Institute for Theoretical Physics（Perimeter理论物理研究所）；Department of Physics and Astronomy, York University（约克大学物理与天文学系）；Department of Physics and Astronomy, University of Waterloo（滑铁卢大学物理与天文学系）；Waterloo Centre for Astrophysics, University of Waterloo（滑铁卢大学滑铁卢天体物理中心）
Cosmological parameter constraints from the CMB power spectra alone suffer several well-known degeneracies. These degeneracies can be broken by numerical artefacts and also a variety of physical effects that become quantitatively important with high-accuracy data e.g. from the Planck satellite. We study degeneracies in models with flat and non-flat spatial sections, non-trivial dark energy and massive neutrinos, and investigate the importance of various physical degeneracy-breaking effects. We test the CAMB power spectrum code for numerical accuracy, and demonstrate that the numerical calculat…
Degeneracy is a method to accommodate exact, low energy vacuum states in scalar-tensor gravitational models despite the presence of an arbitrarily large vacuum energy. However, this approach requires very particular combinations of scalar field and metric couplings in the Lagrangian. In this work we study departures from the restrictive degeneracy condition -- starting from a fiducial model containing an exact Minkowski space solution, we break the degeneracy condition in numerous simple ways to test if the resulting models maintain certain key features -- specifically the dynamical cancellati…
We present a numerical analysis supporting the evidence that the redshift evolution of the drifting coefficient of the field cluster mass function is capable of breaking several cosmic degeneracies. This evidence is based on the data from the CoDECS and DUSTGRAIN-pathfinder simulations performed separately for various non-standard cosmologies including coupled dark energy, $f(R)$ gravity and combinations of $f(R)$ gravity with massive neutrinos as well as for the standard $Λ$CDM cosmology. We first numerically determine the field cluster mass functions at various redshifts in the range of $0\l…
Probing Baryons with the Kinematic Sunyae Zel'dovich Effect and Machine Learning Derived Peculiar Velocities using DESI DR2 and ACT DR6
Cornell University（康奈尔大学）；University of Pennsylvania（宾夕法尼亚大学）；Kavli Institute for Cosmology Cambridge（卡弗里宇宙学剑桥研究所）；Academia Sinica (ASIAA)（中央研究院天文及天体物理研究所）；Duke University（杜克大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Boston University（波士顿大学）；Instituto Avanzado de Cosmología A. C.（先进宇宙学研究所）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）
We study the fit of cosmological models with two additional free parameters $N_\mathrm{eff}$ and $ξ_e$ in addition to the parameters of $Λ$CDM. We introduce extra radiation components such as hot axions or sterile neutrinos in addition to the energy density of neutrinos with large neutrino degeneracy. Then, a larger $N_\mathrm{eff}$ is allowed without spoiling Big Bang Nucleosynthesis (BBN), as positive neutrino degeneracy $ξ_e$ could improve BBN fit. By analysing the data from Planck, baryon acoustic oscillation (BAO), BBN and type-Ia supernovae (SNeIa), it can be seen that the Hubble tension…
We show the advantages of a wedding cake design for Sunyaev-Zel'dovich cluster surveys. We show that by dividing up a cluster survey into a wide and a deep survey, one can essentially recover the cosmological information that would be diluted in a single survey of the same duration due to the uncertainties in our understanding of cluster physics. The parameter degeneracy directions of the deep and wide surveys are slightly different, and combining them breaks these degeneracies effectively. A variable depth survey with a few thousand clusters is as effective at constraining cosmological parame…
A new measurement of the FRB DM-galaxy cross correlation and a first joint analysis with the kinematic SZ effect
Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Owens Valley Radio Observatory, California Institute of Technology（加州理工学院欧文谷射电天文台）；Department of Astronomy/Steward Observatory, University of Arizona（亚利桑那大学天文学系/斯蒂沃德天文台）；Department of Physics, University of Arizona（亚利桑那大学物理系）
Line intensity mapping is rapidly gaining prominence as a tool to understand galaxy evolution and cosmology at high redshift. However, the standard power spectrum analysis for these surveys suffers from a tight degeneracy between the overall mean line intensity and the bias of the emitting galaxies. We outline a new formalism for the Voxel Intensity Distribution (VID), a one-point statistic which is known to contain information beyond the power spectrum. We use this new calculation to show for the first time that the VID can be used to break this key degeneracy in intensity mapping data.
Measurement of the galaxy-velocity power spectrum of DESI tracers with the kinematic Sunyaev-Zeldovich effect using DESI DR2 and ACT DR6
Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；Berkeley Center for Cosmological Physics, Department of Physics, University of California, Berkeley（加州大学伯克利分校物理系宇宙学物理中心）；Center for Cosmology and AstroParticle Physics, The Ohio State University（俄亥俄州立大学宇宙学与天体粒子物理中心）；Department of Physics, The Ohio State University（俄亥俄州立大学物理系）；Department of Physics, Boston University（波士顿大学物理系）；Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano（米兰大学阿尔多·庞特莫利物理系）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；Department of Physics & Astronomy, University College London（伦敦大学学院物理与天文学系）
