arXiv subjects

Amy Wayland

Publications and source records attributed to Amy Wayland.

10 recordsLinked to original sources

arXiv2026

Joint analysis of the Macquart relation and the dispersion measure power spectrum: cross-covariance and redshift self-calibration

The dispersion measures (DMs) of fast radio bursts (FRBs) trace ionised baryons along the line of sight, probing baryonic feedback. Two complementary observables can be constructed from an FRB catalogue: the DM-redshift (Macquart) relation of host-identified FRBs, and the angular power spectrum of the DM field of the full catalogue. Their joint analysis requires their cross-covariance. We derive it within the halo model and show it is a super-sample effect: only the monopole of an individual DM correlates with the angular power spectrum, yielding an exact, model-independent bound on the correlation coefficient. We validate the calculation against log-normal forward simulations of $10^4$ FRBs. For individual DMs, the correlation with the bandpowers is at the per cent level. Neglecting the cross-covariance changes the width of the $χ^2$ distribution by only 0.8 per cent, so the two observables can be treated as effectively independent for wide-area surveys. In a joint forecast with an LSST-like weak lensing survey, adding the Macquart relation tightens constraints on the physical baryon density by 32 per cent and on the mean host contribution by a factor of 4.1, while improving baryonification parameters by only about 5 per cent, indirectly through the host contribution. Finally, we show that the redshift distribution of FRBs without identified hosts, which enters every DM power spectrum, can be reconstructed by inverting their DMs with the jointly fitted mean relation without biasing the inferred parameters, whereas a 20 per cent error in the mean relation biases the DM power spectrum by up to 2$σ$ per band for $5\times 10^5$ FRBs.

astro-ph.CO↗

arXiv2026

Sound-Horizon-Agnostic Forecast for Constraints on $H_0$ and $Σm_ν$ from BAO, CMB Lensing, Supernovae and LSST-like Galaxy Lensing

We present a sound-horizon-agnostic forecast for constraints on the Hubble constant $H_0$ and the sum of the neutrino masses $Σm_ν$ from a combination of LSST-like galaxy weak lensing, Simons-Observatory-like CMB lensing, the completed DESI BAO program, and expanded supernova samples. Treating the sound horizon at baryon drag $r_d$ as a free parameter, the method provides a consistency test of $Λ$CDM without relying on the standard early-Universe calibration of $r_d$. The analysis incorporates realistic galaxy weak-lensing systematics, explicitly marginalizing over photometric-redshift calibration, multiplicative shear biases, intrinsic alignments, and baryonic feedback, and extends the CMB-lensing analysis to $L_{\max}=5000$. For fixed $Σm_ν$, we forecast uncertainties of $σ(H_0)\simeq 1.5$ km/s/Mpc with our least informative prior set, $σ(H_0)\simeq 1.3$ km/s/Mpc with more restrictive priors, and $σ(H_0)\simeq 0.7$ km/s/Mpc with an additional informative prior on the amplitude of primordial fluctuations $A_s$. Allowing $Σm_ν$ to vary weakens the $H_0$ constraints, while still yielding a forecast 95% CL upper limit of about 0.4 eV on $Σm_ν$. We also clarify the scope of the $r_d$-agnostic approach through validation tests using mock data from modified recombination and early dark energy models. The method recovers unbiased constraints on $H_0$ for the former but not the latter, highlighting its dependence on assumptions about early-Universe physics.

astro-ph.CO↗

arXiv2026

The impact of feedback and cosmology on Cosmic Infrared Background cross-correlations

We study the evolution and clustering properties of the star formation rate density (SFR) $ρ_{\rm SFR}$ in the FLAMINGO suite of hydrodynamical simulations, with the aim of exploring the possibility of constraining AGN and stellar feedback prescription, as well as the effect of cosmology, using cross-correlations between the Cosmic Infrared Background (CIB) and other tracers of the large-scale structure. Specifically, we consider tomographic measurements of the bias-weighted SFR-density $\langle bρ_{\rm SFR}\rangle$, as well as cross-correlations between the CIB and cosmic shear as a probe of the $ρ_{\rm SFR}$-matter correlation. Most of the FLAMINGO models calibrated against the $z=0$ galaxy stellar mass function (SMF) yield similar predictions for the distribution and clustering of star-forming systems, and thus it is difficult to derive clean conclusions regarding the impact of AGN feedback or cosmology on CIB statistics. However, we show that current measurements of $\langle bρ_{\rm SFR}\rangle$, as well as CIB-shear cross-correlations clearly disfavour models with strong stellar feedback, as well as simulations with strong kinetic (jet-driven) AGN feedback, even under the fiducial SMF calibration. This study demonstrates the potential of CIB cross-correlations to study aspects of the physics of star and galaxy formation in a cosmological setting.

astro-ph.CO↗

arXiv2026

Joint measurements of thermal Sunyaev-Zel'dovich and cosmic infrared background cross-correlations with cosmic shear

The cross-correlation between weak lensing (WL) and the thermal Sunyaev-Zel'dovich (tSZ) effect probes the connection between the matter distribution and the thermal state of baryons at low redshift ($z\lesssim1$). A key systematic in such measurements is contamination by extragalactic foregrounds, particularly the cosmic infrared background (CIB). Here we describe the CIB spectral energy distribution (SED) with a small number of physically motivated spectral parameters, calibrated against external measurements of the radiation field intensity in galaxies. Their uncertainty is then propagated into the recovered WL$\times$tSZ signal in component separation at the level of the multi-frequency cross-power spectra rather than the map level. Applying this method to cosmic shear from the Dark Energy Survey and frequency maps from Planck, we show that the resulting measurements of the WL$\times$tSZ power spectrum are insensitive to variations in the effective CIB spectral index, radio source contamination, and the scale and redshift dependence of the SED. The measurements are robust to realistic foreground uncertainties, supporting their use as probes of baryonic feedback and cosmology, and providing a framework for future high-precision surveys. We compare our measurements with the Flamingo suite of hydrodynamical simulations and find that they are compatible with the Flamingo predictions for a low amplitude of matter fluctuations, parametrised by $S_8$, strongly disfavouring the larger $S_8$ preferred by Planck. This result is independent of the impact of baryonic feedback as modelled in Flamingo.

astro-ph.CO↗

arXiv2026

The moving lens effect: analytical modelling and foreground suppression

The moving lens (ML) effect is a secondary anisotropy of the cosmic microwave background (CMB) generated by the transverse motion of gravitational potentials, providing a direct probe of the large-scale cosmic velocity field. Its detection relies on cross-correlating a CMB map with the transverse galaxy momentum field, constructed from the galaxy overdensity and a velocity field reconstructed from it. Restricting the reconstruction to large-scale modes strongly suppresses contamination from small-scale astrophysical foregrounds while preserving the ML signal. In this work, we develop a theoretical framework for the ML estimator and its foreground contamination. We show that the signal and foregrounds have a distinct dependence on the direction of the long-wavelength mode represented by the reconstructed galaxy velocity. In the squeezed limit enforced by the velocity reconstruction filter, the bispectrum sourcing the foreground correlation becomes independent of this direction, causing its leading contribution to vanish after angular averaging. In turn, the ML signal survives by matching this directional dependence, with its amplitude reduced only by the filtered velocity variance. Using the halo model, we derive the leading corrections beyond the squeezed limit and show that the residual contamination remains parametrically suppressed. Finally, we model the cross-correlation exactly in the curved sky, and show that it is sourced solely by the longitudinal component of the galaxy momentum field, in the form of a spin-1 $E$-mode, with all other contributions either strongly suppressed on small scales or exactly zero.

astro-ph.CO↗

arXiv2026

Dipoles for everyone: the pseudo-$C_\ell$ approach to directional stacking

Stacking (i.e. averaging) the value of a given astrophysical field around sources allows us to detect new cosmological signatures, such as the kinematic Sunyaev-Zel'dovich, and gain insight on the astrophysical properties of galaxies and their environment. Further information may be gained by orienting these stacks along preferred axes defined by a local directed field, such as the transverse galaxy velocities, galaxy shapes, or the local tidal forces. Examples of this are searches for the moving lens effect, the detection of dipole signatures, or the study of cosmic filaments. Here we show that all directional stacking signals may be reconstructed, without loss of information, in terms of the cross-power spectrum between the quantity of interest and the $E$ and $B$ modes of the spin field used to define the preferred axes weighted by the local galaxy density. The power spectrum approach has several practical advantages, in terms of speed, finite-resolution effects, data visualisation, and combination with other cosmological probes. We also argue that, in some cases, such as stacking using velocities or tidal forces reconstructed from the density field, the recovered signal may be dominated by information that is already present in the cross-spectrum between the target field and the galaxy overdensity itself.

astro-ph.CO↗

arXiv2026

Probing baryonic feedback with fast radio bursts: joint analyses with cosmic shear and galaxy clustering

Cosmological inference from weak lensing (WL) surveys is increasingly limited by uncertainties in baryonic physics, which suppress the non-linear matter power spectrum on small scales. Multi-probe analyses that incorporate complementary tracers of the gas distribution around haloes offer a pathway to calibrate these effects and recover unbiased cosmological information. In this work, we forecast the constraining power of a joint analysis combining fiducial data from a Stage-IV WL survey with measurements of the dispersion measure from fast radio bursts (FRBs). We evaluate the ability of this approach to simultaneously constrain cosmological parameters and the astrophysical processes governing baryonic feedback, and we quantify the impact of key FRB systematics, including redshift uncertainties and source clustering. We find that, even after accounting for these effects, a 3$\times$2-point analysis of WL and FRBs significantly improves cosmological constraints, reducing the degradation factor on $S_8$ by $\sim 80\%$ compared to WL alone. We further show that FRBs alone are sensitive only to a degenerate combination of the key baryonic parameters, $\log_{10} M_{\rm c}$ and $η_{\rm b}$, and that the inclusion of WL measurements breaks this degeneracy. Finally, we extend our framework to incorporate galaxy clustering measurements using Luminous Red Galaxy and Emission Line Galaxy samples, performing a unified 6$\times$2-point analysis of WL, dispersion measures of FRBs, and galaxy clustering. While this combined approach tightens constraints on $Ω_{\rm m}$ and $\log_{10} M_{\rm c}$, it does not lead to a significant improvement in $S_8$ constraints beyond those obtained from WL and FRBs alone.

astro-ph.CO↗

arXiv2025

kSZ for everyone: the pseudo-Cl approach to stacking

We present a harmonic-space estimator for the cross-correlation between the kinematic Sunyaev-Zel'dovich effect and the reconstructed galaxy momentum field that offers several practical advantages over the traditional stacking approach. The estimator is easy to deploy using relatively modest computational resources and recovers all information available in the galaxy-kSZ cross-correlation. In particular, by using well-understood power spectrum estimation techniques, its statistical uncertainties, including potential correlated uncertainties with other large-scale structure observables, can be easily and accurately estimated. Moreover, standard kSZ stacking measurements can be reconstructed exactly from the estimator at a lower computational cost, employing harmonic-space, catalog-level techniques to recover all small-scale information.

astro-ph.CO↗

arXiv2025

Detailed theoretical modelling of the kinetic Sunyaev-Zel'dovich stacking power spectrum

We examine, from first principles, the angular power spectrum between the kinematic Sunyaev-Zel'dovich effect (kSZ) and the reconstructed galaxy momentum - the basis of existing and future "kSZ stacking" analyses. We present a comprehensive evaluation of all terms contributing to this cross-correlation, including both the transverse and longitudinal modes of the density-weighted velocity field, as well as all irreducible correlators that contribute to the momentum power spectrum. This includes the dominant component, involving the convolution of the electron-galaxy and velocity-velocity power spectra, an additional disconnected cross-term, and a connected non-Gaussian trispectrum term. Using this framework, we examine the impact of other commonly neglected contributions, such as the two-halo component of the dominant term, and the impact of satellite galaxies. Finally, we assess the sensitivity of upcoming CMB experiments to these effects and determine that they will be sensitive to the cross-term, the connected non-Gaussian trispectrum term, the two-halo contribution and impact of satellite galaxies, at a significance level of $\sim 4-6 σ$. On the other hand, the contribution from longitudinal modes is negligible in all cases. These results identify the astrophysical observables that must be accurately modelled to obtain unbiased constraints on cosmology and astrophysics from near-future kSZ measurements.

astro-ph.CO↗

arXiv2025

Calibrating baryonic effects in cosmic shear with external data in the LSST era

Cosmological constraints derived from weak lensing (WL) surveys are limited by baryonic effects, which suppress the non-linear matter power spectrum on small scales. By combining WL measurements with data from external tracers of the gas around massive structures, it is possible to calibrate baryonic effects and, therefore, obtain more precise cosmological constraints. In this study, we generate mock data for a Stage-IV weak lensing survey such as the Legacy Survey of Space and Time (LSST), X-ray gas fractions, and stacked kinetic Sunyaev-Zel'dovich (kSZ) measurements, to jointly constrain cosmological and astrophysical parameters describing baryonic effects (using the Baryon Correction Model - BCM). First, using WL data alone, we quantify the level to which the BCM parameters will need to be constrained to recover the cosmological constraints obtained under the assumption of perfect knowledge of baryonic feedback. We identify the most relevant baryonic parameters and determine that they must be calibrated to a precision of $\sim 10$-$20\%$ to avoid significant degradation of the fiducial WL constraints. We forecast that long-term X-ray data from $\sim 5000$ clusters should be able to reach this threshold for the parameters that characterise the abundance of hot virialised gas. Constraining the distribution of ejected gas presents a greater challenge, however, but we forecast that long-term kSZ data from a CMB-S4-like experiment should achieve the level of precision required for full self-calibration.

astro-ph.CO↗