arXiv subjects

Abhishek S. Maniyar

Publications and source records attributed to Abhishek S. Maniyar.

At least 19 recordsLinked to original sources

arXiv2026

Non-linear halo bias for accurate modelling of cosmic infrared background anisotropies

Halo models provide the standard framework for interpreting cosmic infrared background (CIB) anisotropies and inferring the connection between dusty star-forming galaxies and their host dark matter halos. Recent studies have shown that inaccuracies in the modelling of halo clustering may bias the inferred parameters governing star formation in dark matter halos. In this work, we investigate whether a more detailed description of halo clustering can alleviate these shortcomings. We incorporate a scale-dependent, non-linear correction to the halo bias within a halo-model framework based on a simple SFR-halo mass parametrisation. We consider both a full mass-dependent implementation and a computationally efficient approximation. We also investigate the impact of updated (sub)halo mass functions. We validate the revised framework using mock observations derived from a dedicated simplified version of the SIDES-Uchuu simulation, combining the SIDES empirical galaxy model with the Uchuu N-body simulation, specifically designed to match the SFR prescriptions adopted in our halo-model. The corrections modify the predicted CIB clustering by up to 30% on intermediate scales, while the effective implementation reproduces the full treatment at the sub-percent level. The updated model removes the scale-dependent discrepancies previously identified and accurately reproduces the measured power spectra over the full multipole range. In MCMC analyses, the input SFR parameters are recovered with substantially reduced biases, with all input parameters recovered within their $1σ$ confidence intervals. Our results demonstrate that accurately modelling non-linear halo clustering is essential not only to reproduce CIB anisotropies, but also to reliably recover the underlying galaxy-halo connection. The framework presented here provides a validated foundation for future analyses of observational data.

astro-ph.CO↗

arXiv2026

Peering Beyond the Veil of Last Scattering: A View of the Universe with CMB Spectral Distortions

The frequency spectrum of the cosmic microwave background is the most precise blackbody ever measured in nature, with deviations constrained at the level of almost one part per million from the COBE satellite. Nevertheless, departures away from a perfect blackbody are present in standard $Λ$CDM cosmology, lurking just beneath the surface of our current observational bounds. These spectral distortions provide invaluable information on our thermal history in both the post- and pre-recombination epochs, allowing us to peer beyond last scattering and into the primordial Universe. Here, we present an overview of the underlying physics responsible for generating CMB spectral distortions at all epochs. As an illustration of this rich physics, we review a comprehensive set of mechanisms capable of generating distortions both within and beyond the standard $Λ$CDM paradigm. We also discuss the information that can be gleaned by going beyond the monopole (sky-averaged) spectrum and exploiting the spatial information present in anisotropic spectral distortions. To supplement our discussion of the diverse science of spectral distortions, we provide an overview of the upcoming and proposed experimental landscape. We highlight that the combination of the TMS, COSMO, and BISOU experiments will provide the first discovery of a monopole $y$-type distortion within the coming decade. From space, the proposed FOSSIL experiment is forecasted to improve upon the original COBE/FIRAS measurement by roughly three orders of magnitude in sensitivity, bringing with it the detection of the $Λ$CDM $μ$-type distortion sourced by the dissipation of small scale acoustic modes in the pre-recombination plasma. With transformational measurements on the horizon, CMB spectral distortions offer a uniquely sensitive probe of the thermal history of the Universe at redshifts $z \lesssim 2 \times 10^6$.

astro-ph.CO↗

arXiv2026

Foreground Mitigation for CMB Lensing with the Global Minimum Variance Quadratic Estimator

Weak gravitational lensing of the cosmic microwave background (CMB) is a powerful probe of cosmology, providing insight into structure formation and the evolution of the universe. Current and upcoming CMB experiments such as SPT-3G and the Simons Observatory (SO) provide high-resolution, low-noise temperature and polarization maps that are ideal for lensing reconstruction. The global minimum variance (GMV) quadratic estimator for CMB lensing reduces reconstruction noise over the standard quadratic estimator (SQE). In this work, we extend the GMV framework to incorporate the tSZ-deproj and cross-ILC foreground mitigation techniques, which enhance robustness against contamination from astrophysical sources. For a simulation study using SPT-3G Ext-10k and SO Extended configurations at $\ell_{\mathrm{max}}^T = 3500$, the lensing bias at $L < 1000$ is reduced from $\sim4\%$ with standard GMV and SQE to $2\%$ with tSZ-deproj, and to $< 1\%$ with cross-ILC. These methods enable the construction of foreground-cleaned lensing maps suitable for cross-correlation analyses, with direct relevance for current and future surveys.

astro-ph.CO↗

arXiv2025

The Atacama Cosmology Telescope: A search for late-time anisotropic screening of the Cosmic Microwave Background

Since the formation of the first stars, most of the gas in the Universe has been ionized. Spatial variations in the density of this ionized gas generate cosmic microwave background anisotropies via Thomson scattering, a process known as the ``anisotropic screening'' effect. We propose and implement for the first time a new estimator to cross-correlate unWISE galaxies and anisotropic screening, as measured by the Atacama Cosmology Telescope and Planck satellite. We do not significantly detect the effect; the null hypothesis is consistent with the data at 1.7 $σ$ (resp. 0.016 $σ$) for the blue (resp. green) unWISE sample. We obtain an upper limit on the integrated optical depth within a 6 arcmin disk to be $\barτ< 0.033$ arcmin$^2$ at 95\% confidence for the blue sample and $\barτ< 0.057$ arcmin$^2$ for the green sample. Future measurements with Simons Observatory and CMB-S4 should detect this effect significantly. Complementary to the kinematic Sunyaev-Zel'dovich effect, this probe of the gas distribution around halos will inform models of feedback in galaxy formation and baryonic effects in galaxy lensing.

astro-ph.CO↗

arXiv2025

A new "temperature inversion" estimator to detect CMB patchy screening by large-scale structure

Thomson scattering of cosmic microwave background (CMB) photons imprints various properties of the baryons around galaxies on the CMB. One such imprint, called patchy screening, is a direct probe of the gas density profile around galaxies. It usefully complements the information from the kinematic and thermal Sunyaev-Zel'dovich effects and does not require individual redshifts. In this paper, we derive new estimators of patchy screening called the "temperature inversion" (TI) and "signed" estimators, analogous to the gradient inversion estimator of CMB lensing. Pedagogically, we clarify the relation between these estimators and the standard patchy screening quadratic estimator (QE). The new estimators trade optimality for robustness to biases caused by the dominant CMB lensing and foreground contaminants, allowing the use of smaller angular scales. We perform a simulated analysis to realistically forecast the expected precision of patchy screening measurements from four CMB experiments, ACT, SPT, Simons Observatory (SO) and CMB-S4, cross-correlated with three galaxy samples from BOSS, unWISE and the simulated Rubin LSST Data Challenge 2 catalog. Our results give further confidence in the first detection of this effect from the ACT$\times$unWISE data in the companion paper and show patchy screening will be a powerful observable for future surveys like SO, CMB-S4 and LSST. Implementations of the patchy screening QE and the TI and signed estimators are publicly available in our LensQuEst and ThumbStack software packages, available at https://github.com/EmmanuelSchaan/LensQuEst and https://github.com/EmmanuelSchaan/ThumbStack , respectively.

astro-ph.CO↗

arXiv2025

The Cosmic Microwave Background -- Secondary Anisotropies

The cosmic microwave background (CMB), the relic radiation from the early Universe, offers a unique window into both primordial conditions and the intervening large-scale structure (LSS) it traverses. Interactions between CMB photons and the evolving Universe imprint secondary anisotropies -- modifications to the CMB's intensity and polarization caused by gravitational effects and scattering processes. These anisotropies serve as a powerful probe of fundamental physics while also revealing astrophysical processes governing the thermodynamics and distribution of baryonic matter. In this chapter, we provide a comprehensive review of the physical mechanisms underlying secondary anisotropies, their observational status, and their potential to advance precision cosmology. With the increasing sensitivity of CMB experiments and synergy with LSS surveys, secondary anisotropies are poised to unveil unprecedented insights into the Universe's composition, evolution, and dynamics.

astro-ph.CO↗

arXiv2024

Constraining Cosmology With the CMB $\times$ LIM-Nulling Convergence

Lensing reconstruction maps from the cosmic microwave background (CMB) provide direct observations of the matter distribution of the universe without the use of a biased tracer. Such maps, however, constitute projected observables along the line of sight that are dominated by their low-redshift contributions. To cleanly access high-redshift information, Maniyar et al. showed that a linear combination of lensing maps from both CMB and line intensity mapping (LIM) observations can exactly null the low-redshift contribution to CMB lensing convergence. In this paper we explore the scientific returns of this nulling technique. We show that LIM-nulling estimators can place constraints on standard $Λ$CDM plus neutrino mass parameters that are competitive with traditional CMB lensing. Additionally, we demonstrate that as a clean probe of the high-redshift universe, LIM-nulling can be used for model-independent tests of cosmology beyond $Λ$CDM and as a probe of the high-redshift matter power spectrum.

astro-ph.CO↗

arXiv2024

A New Probe of the High-z BAO scale: BAO tomography With CMB $\times$ LIM-Nulling Convergence

Standard rulers such as the baryon acoustic oscillation (BAO) scale serve as workhorses for precision tests of cosmology, enabling distance measurements that probe the geometry and expansion history of our Universe. Aside from BAO measurements from the cosmic microwave background (CMB), most standard ruler techniques operate at relatively low redshifts and depend on biased tracers of the matter density field. In a companion paper, we explored the scientific reach of nulling estimators, where CMB lensing convergence maps are cross-correlated with linear combinations of similar maps from line intensity mapping (LIM) to precisely null out the low-redshift contributions to CMB lensing. We showed that nulling estimators can be used to constrain the high redshift matter power spectrum and showed that this spectrum exhibits discernible BAO features. Here we propose using these features as a standard ruler at high redshifts that does not rely on biased tracers. Forecasting such a measurement at $z \sim 5$, we find that next-generation instruments will be able to constrain the BAO scale to percent-level precision at $7.2 \%$, while our futuristic observing scenario can constrain the BAO scale to $4\%$ precision. This constitutes a fundamentally new kind of BAO measurement during early epochs in our cosmic history.

astro-ph.CO↗

arXiv2024

The star formation, dust, and abundance of galaxies with unWISE-CIB cross-correlations

The cosmic infrared background (CIB) is the accumulated infrared (IR) radiation mainly from interstellar dust heated up by early stars. In this work, we measure the cross-correlation between galaxies from the unWISE catalog and the CIB maps from the Planck satellite to simultaneously constrain the cosmic star formation rate (SFR), dust spectral energy distribution (SED), and the halo occupation distribution (HOD). The unWISE galaxy catalog is divided into three tomographic bins centered at $z\sim 0.6, 1.1, 1.5$, and the CIB maps are at 353, 545, and 857 GHz. We measure the cross-correlations between these galaxy samples and CIB maps and get a 194$σ$ signal within an angular scale $100<\ell<2000$, from which we constrain two CIB halo models from previous literature and one new model. The SFR, SED, and HOD model parameters are constrained consistently among the three models. Specifically, the dust temperature at $z=0$ is constrained $T_0={21.14}^{+1.02}_{-1.34}$ K, which is slightly lower than $T_0=24.4\pm1.9$ K measured by the Planck collaboration. The halo mass that gives the most efficient star formation is around $10^{{11.79}^{+0.73}_{-0.86}}M_{\odot}$. From the model parameters, combined with the SFR density at $z=0$ synthesized from multi-wavelength observations, we break the degeneracy between SED and SFR and recover the cosmic star formation history that is consistent with multi-wavelength surveys. We also constrain the graybody SED model in agreement with previous measurements from infrared flux stacking. From the HOD constraints, we derive an increasing trend of galaxy linear bias along redshifts that agrees with the results from cross- and auto-correlation with unWise galaxies. This study indicates the power of using CIB-galaxy cross-correlation to study star formation, dust, and abundance of galaxies across cosmic time.

astro-ph.CO↗

arXiv2023

Characterizing the Conditional Galaxy Property Distribution using Gaussian Mixture Models

Line-intensity mapping (LIM) is a promising technique to constrain the global distribution of galaxy properties. To combine LIM experiments probing different tracers with traditional galaxy surveys and fully exploit the scientific potential of these observations, it is necessary to have a physically motivated modeling framework. As part of developing such a framework, in this work we introduce and model the conditional galaxy property distribution (CGPD), i.e. the distribution of galaxy properties conditioned on the host halo mass and redshift. We consider five galaxy properties, including the galaxy stellar mass, molecular gas mass, galaxy radius, gas phase metallicity and star formation rate (SFR), which are important for predicting the emission lines of interest. The CGPD represents the full distribution of galaxies in the five dimensional property space; many important galaxy distribution functions and scaling relations, such as the stellar mass function and SFR main sequence, can be derived from integrating and projecting it. We utilize two different kinds of cosmological galaxy simulations, a semi-analytic model and the IllustrisTNG hydrodynamic simulation, to characterize the CGPD and explore how well it can be represented using a Gaussian mixture model (GMM). We find that with just a few ($\sim 3$) Gaussian components, a GMM can describe the CGPD of the simulated galaxies to high accuracy for both simulations. The CGPD can be mapped to LIM or other observables by constructing the appropriate relationship between galaxy properties and the relevant observable tracers.

astro-ph.GA↗

arXiv2023

Extragalactic CO emission lines in the CMB experiments: a forgotten signal and a foreground

High resolution cosmic microwave background (CMB) experiments have allowed us to precisely measure the CMB temperature power spectrum down to very small scales (multipole $\ell \sim 3000$). Such measurements at multiple frequencies enable separating the primary CMB anisotropies with other signals like CMB lensing, thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ), and cosmic infrared background (CIB). In this paper, we explore another signal of interest at these frequencies that should be present in the CMB maps: extragalactic CO molecular rotational line emissions, which are the most widely used tracers of molecular gas in the line intensity mapping experiments. Using the SIDES simulations adopted for top hat bandpasses at 150 and 220 GHz, we show that the cross-correlation of the CIB with CO lines has a contribution similar to the CIB-tSZ correlation and the kSZ power, thereby contributing a non-negligible amount to the total power at these scales. This signal, therefore, may significantly impact the recently reported $\geq 3σ$ detection of the kSZ power spectrum from the South Pole Telescope (SPT) collaboration, as the contribution of the CO lines is not considered in such analyses. Our results also provide a new way of measuring the CO power spectrum in cross-correlation with the CIB. Finally, these results show that the CO emissions present in the CMB maps will have to be accounted for in all the CMB auto-power spectrum and cross-correlation studies involving a LSS tracer.

astro-ph.CO↗

arXiv2022

Cosmic star formation history with tomographic cosmic infrared background-galaxy cross-correlation

In this work, we probe the star formation history of the Universe using tomographic cross-correlation between the cosmic infrared background (CIB) and galaxy samples. The galaxy samples are from the Kilo-Degree Survey (KiDS), while the CIB maps are made from \planck\, sky maps. We measure the cross-correlation in harmonic space with a significance of 43$σ$. We model the cross-correlation with a halo model, which links CIB anisotropies to star formation rates (SFR) and galaxy abundance. We assume that SFR has a lognormal dependence on halo mass, while galaxy abundance follows the halo occupation distribution (HOD) model. The cross-correlations give a best-fit maximum star formation efficiency of $η_{\mathrm{max}}= 0.41^{+0.09}_{-0.14}$ at a halo mass $\log_{10}(M_{\mathrm{peak}}/M_{\odot})= {12.14\pm 0.36}$. The derived star formation rate density (SFRD) is well constrained up to $z\sim 1.5$. The constraining power at high redshift is mainly limited by the KiDS survey depth. A combination with external SFRD measurements from previous studies gives $\log_{10}(M_{\mathrm{peak}}/M_{\odot})=12.42^{+0.35}_{-0.19}$. This tightens the SFRD constraint up to $z=4$, yielding a peak SFRD of $0.09_{-0.004}^{+0.003}\,M_{\odot} \mathrm { year }^{-1} \mathrm{Mpc}^{-3}$ at $z=1.74^{+0.06}_{-0.02}$, corresponding to a lookback time of $10.05^{+0.12}_{-0.03}$ Gyr. Both constraints are consistent, and the derived SFRD agrees with previous studies and simulations. Additionally, we estimate the galaxy bias $b$ of KiDS galaxies from the constrained HOD parameters and yield an increasing bias from $b=1.1_{-0.31}^{+0.17}$ at $z=0$ to $b=1.96_{-0.64}^{+0.18}$ at $z=1.5$. Finally, we provide a forecast for future galaxy surveys and conclude that, due to their considerable depth, future surveys will yield a much tighter constraint on the evolution of the SFRD.

astro-ph.GA↗

arXiv2022

Constraining the Star Formation Rate using Joint CIB Continuum and [CII] Intensity Mapping

Line intensity mapping (LIM) experiments probing the nearby universe can expect a considerable amount of cosmic infrared background (CIB) contiuum emission coming from near and far-infrared galaxies. For the purpose of using the LIM data to constrain the star formation rate (SFR), we argue that the CIB continuum - traditionally treated as contamination - can be combined with the LIM signal to enhance the SFR constraints achievable. We first present a power spectrum model that is capable of joining continuum and line emissions that assume the same prior SFR model. We subsequently analyze the effectiveness of the joint model in the context of the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM), which utilizes the [CII] molecular line to study the SFR. We numerically compute the theoretical power spectra according to our model and the EXCLAIM survey specifics, and perform Fisher analysis to obtain SFR parameter constraints. We find that although the joint model has no considerable advantage over LIM alone assuming the current survey level of EXCLAIM, its effects become significant when we consider more optimistic values of survey resolution and angular span that are expected of future LIM experiments. By manipulating the Fisher formalism, we show that the CIB is not only an additional SFR sensitive signal, but also serves to break the SFR parameter degeneracy that naturally emerges from the [CII] Fisher matrix. For this reason, addition of the CIB will allow improvements in the survey parameters to be better reflected in the SFR constraints, and can be effectively utilized by future LIM experiments.

astro-ph.CO↗

arXiv2022

Constraints on primordial non-Gaussianity from halo bias measured through CMB lensing cross-correlations

Local non-Gaussianities in the initial conditions of the Universe, parameterized by $f_{\rm NL}$, induce a scale-dependence in the large-scale bias of halos in the late Universe. This effect is a promising path to constrain multi-field inflation theories that predict non-zero $f_{\rm NL}$. While most existing constraints from the halo bias involve auto-correlations of the galaxy distribution, cross-correlations with probes of the matter density provide an alternative channel with fewer systematics. We present the strongest large-scale structure constraint on local primordial non-Gaussianity that uses cross-correlations alone. We use the cosmic infrared background (CIB) consisting of dusty galaxies as a halo tracer and cosmic microwave background (CMB) lensing as a probe of the underlying matter distribution, both from \textit{Planck} data. Milky Way dust is a key challenge in using the large-scale modes of the CIB. Importantly, the cross-correlation of the CIB with CMB lensing is far less affected by Galactic dust compared to the CIB auto-spectrum, which picks up an additive bias from Galactic dust. We find no evidence for primordial non-Gaussianity and find $-87<f_{\rm NL}<19$ with a Gaussian $σ(f_{\rm NL})\approx 41$, assuming universality of the halo mass function. We find that future CMB lensing data from Simons Observatory and CMB-S4 could achieve $σ(f_{\rm NL})$ of 23 and 20 respectively. The constraining power of such an analysis is limited by current Galactic dust cleaning techniques, requiring us to use a minimum multipole of $\ell=70$. If this challenge is overcome with improved analysis techniques or external data, constraints as tight as $σ(f_{\rm NL})=4$ can be achieved through the cross-correlation technique. More optimistically, constraints better than $σ(f_{\rm NL})=2$ could be achieved if the CIB auto-spectrum is dust-free down to the largest scales.

astro-ph.CO↗

arXiv2022

Snowmass2021: Opportunities from Cross-survey Analyses of Static Probes

Cosmological data in the next decade will be characterized by high-precision, multi-wavelength measurements of thousands of square degrees of the same patches of sky. By performing multi-survey analyses that harness the correlated nature of these datasets, we will gain access to new science, and increase the precision and robustness of science being pursued by each individual survey. However, effective application of such analyses requires a qualitatively new level of investment in cross-survey infrastructure, including simulations, associated modeling, coordination of data sharing, and survey strategy. The scientific gains from this new level of investment are multiplicative, as the benefits can be reaped by even present-day instruments, and can be applied to new instruments as they come online.

hep-ex↗

arXiv2022

Doppler boosted dust emission and CIB-galaxy cross-correlations: a new probe of cosmology and astrophysics

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-Prime and DESI-like experiments. We show that it also acts as a new CMB foreground which can bias future kSZ cross-correlations, if not properly accounted for.

astro-ph.CO↗

arXiv2022

An empirical representation of a physical model for the ISM [CII], CO, and [CI] emission at redshift $1\leq z\leq9$

Sub-millimeter emission lines produced by the interstellar medium (ISM) are strong tracers of star formation and are some of the main targets of line intensity mapping (LIM) surveys. In this work we present an empirical multi-line emission model that simultaneously covers the mean, scatter, and correlations of [CII], CO J=1-0 to J=5-4, and [CI] lines in redshift range $1\leq z\leq9$. We assume the galaxy ISM line emission luminosity versus halo mass relations can be described by double power laws with redshift-dependent log normal scatter. The model parameters are then derived by fitting to the state of the art semi-analytic simulation results that have successfully reproduced multiple sub-millimeter line observations at $0\leq z\lesssim6$. We cross check the line emission statistics predicted by the semi-analytic simulation and our empirical model, finding that at $z\geq1$ our model reproduces the simulated line intensities with fractional error less than about 10%. The fractional difference is less than 25% for the power spectra. Grounded on physically-motivated and self-consistent galaxy simulations, this computationally efficient model will be helpful in forecasting ISM emission line statistics for upcoming LIM surveys.

astro-ph.GA↗

arXiv2021

Joint analyses of 2D CMB lensing and 3D galaxy clustering in the spherical Fourier-Bessel basis

Cross-correlating cosmic microwave background (CMB) lensing and galaxy clustering has been shown to greatly improve the constraints on the local primordial non-Gaussianity (PNG) parameter $f_{\rm NL}$ by reducing sample variance and also parameter degeneracies. To model the full use of the 3D information of galaxy clustering, we forecast $f_{\rm NL}$ measurements using the decomposition in the spherical Fourier-Bessel (SFB) basis, which can be naturally cross-correlated with 2D CMB lensing in spherical harmonics. In the meantime, such a decomposition would also enable us to constrain the growth rate of structure, a probe of gravity, through the redshift-space distortion (RSD). As a comparison, we also consider the tomographic spherical harmonic (TSH) analysis of galaxy samples with different bin sizes. Assuming galaxy samples that mimic a few future surveys, we perform Fisher forecasts using linear modes for $f_{\rm NL}$ and the growth rate exponent $γ$, marginalized over standard $Λ$ cold dark matter ($Λ$CDM) cosmological parameters and two nuisance parameters that account for clustering bias and magnification bias. Compared to TSH analysis using only one bin, SFB analysis could improve $σ(f_{\rm NL})$ by factors 3 to 12 thanks to large radial modes. With future wide-field and high-redshift photometric surveys like the LSST, the constraint $σ(f_{\rm NL}) < 1$ could be achieved using linear angular multipoles up to $\ell_{\rm min}\simeq 20$. Compared to using galaxy auto-power spectra only, joint analyses with CMB lensing could improve $σ(γ)$ by factors 2 to 5 by reducing degeneracies with other parameters, especially the clustering bias. For future spectroscopic surveys like the DESI or $\textit{Euclid}$, using linear scales, $γ$ could be constrained to $3\,\%$ precision assuming the GR fiducial value.

astro-ph.CO↗