arXiv subjects

Carmelita Carbone

Publications and source records attributed to Carmelita Carbone.

At least 19 recordsLinked to original sources

arXiv2026

Detecting the neutrino mass via the cross-correlation between matter tracers and the ISWRS effect?

This work explores the potential to detect the nonlinear Integrated Sachs Wolfe effect, namely the Rees-Sciama effect (ISWRS), by cross-correlating current and future Cosmic Microwave Background (CMB) experiments -- Simons Observatory, CMB-S4, CMB-HD, and PICO -- with ongoing Large Scale Structure (LSS) surveys, such as Euclid and the Vera Rubin Observatory (LSST). We model the cross-correlation of the ISWRS effect with gravitational potential tracers like galaxy clustering, cosmic shear, and CMB-lensing potential, to forecast results from these experiments. Our analysis also accounts for the presence of massive neutrinos to assess the feasibility of identifying the $ν$$Λ$CDM model and constraining the neutrino mass sum, M$ν$. Our findings indicate that the CMB-lensing potential reconstructed by CMB-HD is expected to provide the most promising results, achieving $\gtrsim$ 5$σ$ detections even under conservative assumptions for detector noise and foregrounds, thereby allowing differentiation between $ν$$Λ$CDM models. Galaxy clustering can also yield significant detections, whereas cosmic shear can provide valuable results only if non-linearities are accurately modelled, beyond the capabilities of currently available analytical approaches. These latter LSS probes do not provide strong constraining power on M$ν$. While our findings suggest that future CMB experiments and LSS surveys will enable the detection of the ISWRS effect, they do not imply significant prospects for imposing new constraints on neutrino masses in the near future.

astro-ph.CO↗

arXiv2026

Methodological Frontiers in 21-cm Intensity Mapping: the Treatment of Systematics and Foreground Contamination

The distribution of neutral hydrogen (HI) in the post-reionization universe traces the cosmic large-scale structure and therefore serves as a powerful cosmological probe. An efficient way to measure its distribution over wide sky areas and redshift ranges is through single-dish intensity mapping, which exploits the autocorrelation signal of each dish in a telescope array while scanning the same sky patch. Thanks to its broad frequency coverage and technical capabilities, SKA-Mid will enable measurements of the integrated 21 cm emission from HI up to redshift $z\sim3$, making single-dish intensity mapping a key observable for probing dark matter and dark energy. Isolating the faint 21 cm cosmological signal without introducing biases is, however, challenging. The 21 cm signal is several orders of magnitude weaker than the astrophysical foregrounds, and its analysis is further affected by instrumental systematics. Overcoming these difficulties requires detailed modelling together with continuous improvements and innovations in data-analysis techniques. Over the past decade, the international community has developed and tested new methods to address current observational challenges and prepare for forthcoming SKA-Mid observations. This chapter reviews recent advances in map-making and component-separation techniques, with particular emphasis on telescope-specific systematics such as beam response and correlated noise. We focus on results obtained in controlled simulation environments, providing a valuable framework for assessing the strengths and limitations of different approaches. Developing robust algorithms capable of accurately handling instrumental effects and sky-model uncertainties is a crucial step toward fully exploiting the cosmological potential of HI intensity-mapping surveys in the SKA Observatory era.

astro-ph.CO↗

arXiv2026

cloelib: A Flexible Python Library for Computing Cosmological Observables in the Euclid Era

cloelib is a Python library developed to compute cosmological observables within the Cosmology Likelihood for Observables in Euclid (CLOE) ecosystem (cloe-org). As cosmology enters a precision era driven by galaxy survey missions such as Euclid, there is a growing need for flexible, efficient, and differentiable software capable of supporting next-generation inference pipelines. cloelib addresses these demands through a modular architecture that interfaces seamlessly with established Boltzmann solvers whilst incorporating JAX-based automatic differentiation to enable gradient-based methods. The library defines consistent protocols for background evolution, perturbations, and non-linear structure formation, and supports a wide range of observables, including photometric and spectroscopic large-scale structure probes, as well as cross-correlations with the Cosmic Microwave Background and galaxy clusters. In its finalised form, cloelib is intended to serve as the reference theory computation infrastructure for Euclid's first cosmological release, bridging traditional numerical cosmology with modern optimisation techniques and emerging machine learning approaches to inference.

astro-ph.CO↗

arXiv2026

cloelike: A Python Library for Cosmological Likelihood Inference in the Euclid Era

cloelike is a Python package providing modular, composable Gaussian likelihood classes for the main cosmological large-scale structure observables targeted by the ESA Euclid space mission. It is a core component of the CLOE (Cosmology Likelihood for Observables in Euclid) ecosystem and interfaces directly with cloelib for theoretical predictions and euclidlib for reading official Euclid data products. The package implements Gaussian likelihoods covering harmonic angular power spectra and real-space two-point correlation functions for weak lensing (WL), photometric galaxy clustering (GCph), and Galaxy-Galaxy Lensing (GGL) in all joint probe combinations (3x2pt, 2x2pt), as well as spectroscopic full-shape power spectrum multipoles, and baryonic Acoustic oscillations (BAO). cloelike is actively used in internal Euclid Consortium analyses and is openly released to support community validation and reproducibility.

astro-ph.CO↗

arXiv2026

DEMNUni: the Sunyaev-Zel'dovich effect in the presence of massive neutrinos and dynamical dark energy

In recent years, the study of secondary anisotropies in the Cosmic Microwave Background has become a fundamental instrument to test our understanding of the Universe. Using a set of lightcones produced with the ``Dark Energy and Massive Neutrino Universe'' $N$-body simulations, we study how different dark energy equations of state and neutrino masses impact the properties of the thermal Sunyaev-Zel'dovich (tSZ) effect, focusing on the signal arising from galaxy clusters and groups. We analyse the distribution of values for the Compton-$y$ parameter and study its angular power spectrum. We find that the distribution of the logarithmic Compton parameter can be fitted with a skewed Gaussian, with a mean that, at fixed dark energy model, decreases linearly with an approximate slope of $10 f_ν$. Regarding the power spectrum of the thermal SZ effect, we find that an increase in $\sum {m_ν}$ is observed as a power-law scaling with respect to $σ_8^{\mathrm{cb}}$, with exponents ranging from 7.3 to 8.1. We also find that models with massless neutrinos typically overestimate Compton-$y$ data extracted from Planck measurements; a better agreement with the simulations is obtained for $\sum m_ν= 0.16$ or $\sum m_ν=0.32$ eV. For all the \texttt{DEMNUni} models we forecast the cumulative signal-to-noise ratio for thermal SZ observations with the LAT instrument of the Simons Observatory; furthermore, we compute a tailored $χ_\mathrm{SNR}^2$ estimator to infer if such models can be distinguished from the reference $Λ$CDM.

astro-ph.CO↗

arXiv2026

Radio sirens: inferring $H_0$ with binary black holes and neutral hydrogen in the era of the Einstein Telescope and the SKA Observatory

A new synergy between gravitational waves (GWs) and the study of the large-scale structure of the Universe is now emerging. Along this line of research, we combine simulated observations of stellar-origin black hole mergers and neutral hydrogen 21 cm line intensity mapping to probe the expansion rate of the Universe through the distance-redshift relation. GW signals from binary black holes provide direct distance information, while neutral hydrogen intensity maps offer a tomographic view of the large-scale structure of the Universe. Using the 3-dimensional density fields of hydrogen as a redshift prior for GW events, we explore a novel dark-sirens-like approach, here termed radio sirens, to measure the late-time expansion history of the Universe. We study the performance of the next-generation GW observatories, such as the Einstein Telescope, to ensure enough statistics and access to high-redshift data. On the other hand, future spectroscopic intensity mapping surveys with the SKA-Mid telescope are expected to trace the underlying dark matter distribution at large scales up to redshift $z\sim 3$. This combined methodology allows us to constrain the Hubble constant to $\sim 8\%$ precision, using around 3,000 GW events with signal-to-noise ratios greater than 150. This corresponds to an improvement of around $90\%$ compared to not considering the information from the neutral hydrogen maps.

astro-ph.CO↗

arXiv2026

Painting a full radio sky -- Empirical mock catalogues with multiple source populations for future radio surveys

Upcoming radio surveys will probe the sky with unprecedented depth and sky coverage, enabling a broad range of cosmological and astrophysical applications, as well as powerful synergies with experiments at other wavelengths. The preparation and scientific exploitation of these surveys require realistic mock catalogues that capture the complexity of the radio sky and the interplay of its emitting components. We present a modular and extensible algorithm for generating empirical simulations over the full radio sky, i.e. a solid angle of $4π$ steradians ($f_{\rm sky}=1$), down to redshift $z=5$, comprising both radio continuum and line emission. The framework combines a simulated dark-matter light-cone with empirically sampled galaxy populations and a probabilistic galaxy-halo assignment scheme, producing self-consistent mock catalogues including multiple radio populations on the same light-cone. We release two public catalogues: a shallow catalogue, fully constrained by existing observational data and limited to flux thresholds of $S_\text{1.4 GHz}^\text{lim} \sim 8\times10^{-5}\ \text{Jy}$ at $1.4\ \text{GHz}$ and $S_\text{21}^\text{lim} \sim 2\ \text{Jy}\cdot\text{Hz}$ for the HI 21 cm line; and a deep catalogue extending the calibrated empirical model to better sensitivities, broadly matching future SKAO surveys, with flux limits of $S_\text{1.4 GHz}^\text{lim} \sim 4\times10^{-5}\ \text{Jy}$ and $S_\text{21}^\text{lim} \sim 0.3\ \text{Jy}\cdot\text{Hz}$. The catalogues include radio continuum active galactic nuclei and star-forming galaxies, together with HI-emitting galaxies, for a total of more than 260 million sources in the shallow catalogue and more than 1 billion in the deep catalogue. We validate the simulations by analysing their statistical properties: the mocks reproduce the targeted clustering and population statistics while retaining minimal physical assumptions.

astro-ph.GA↗

arXiv2026

Needlets and foreground removal for SKAO hydrogen intensity maps

Intensity Mapping (IM) of the 21-cm line of the neutral hydrogen (\textsc{Hi}) has become a compelling new technique to map the large-scale structure of the Universe. One of the main challenges is the presence of strong foreground emissions of several orders of magnitude larger than the \textsc{Hi}~signal. Here, we implement a version of the Principal Component Analysis, a blind component-separation technique, based on a kind of spherical wavelets called needlets. These functions exploit double localization both in real and in harmonic space. We test Need-PCA performances on a set of maps that simulates the SKA MID radio telescope in the AA4 configuration. We compare our results with other component separation methods such as Generalised Morphological Component Analysis (GMCA) and Generalized Needlet Internal Linear Combination (GNILC). All the methods have comparable results, recovering the \textsc{Hi}~signal within 10\% accuracy across the frequency channels, in the multipole range 30 $\lesssim \ell \lesssim$ 136. We also test our pipeline in the presence of systematics such as polarization leakage. We find that the cleaning methods are insensitive to the presence of such systematic, yielding the same results as in the leakage-free case. Finally, under the assumption of a realistic telescope beam with sidelobes, we find that standard PCA and GMCA fails to recover the \textsc{Hi}~signal at larger scales, while the Need-PCA and Need-GMCA are less affected. GNILC tends to over-clean, yielding to a loss of the signal.

astro-ph.IM↗

arXiv2026

Probing Cosmic Expansion and Early Universe with Einstein Telescope

Over the next two decades, gravitational-wave (GW) observations are expected to evolve from a discovery-driven endeavour into a precision tool for astrophysics, cosmology, and fundamental physics. Current second-generation ground-based detectors have established the existence of compact-binary mergers and enabled GW multi-messenger astronomy, but they remain limited in sensitivity, redshift reach, frequency coverage, and duty cycle. These limitations prevent them from addressing many fundamental open questions in cosmology. By the 2040s, wide-field electromagnetic surveys will have mapped the luminous Universe with unprecedented depth and accuracy. Nevertheless, key problems including the nature of dark matter, the physical origin of cosmic acceleration, the properties of gravity on cosmological scales, and the physical conditions of the earliest moments after the Big Bang will remain only partially constrained by electromagnetic observations alone. Progress on these fronts requires access to physical processes and epochs that do not emit light. Gravitational waves provide a unique and complementary observational channel: they propagate over cosmological distances largely unaffected by intervening matter, probe extreme astrophysical environments, and respond directly to the geometry of spacetime. In this context, next-generation GW observatories such as the Einstein Telescope (ET) will be transformative for European astronomy. Operating at sensitivities and frequencies beyond existing detectors, ET will observe binary black holes and neutron stars out to previously inaccessible redshifts, enable continuous high signal-to-noise monitoring of compact sources, and detect gravitational-wave backgrounds of astrophysical and cosmological origin. Together with space-based detectors, ET will play a central role in advancing our understanding of cosmic evolution and fundamental physics.

astro-ph.CO↗

arXiv2025

Standard Sirens in 2040s: Probing the Cosmic Expansion History with Gravitational Waves and Spectroscopic Galaxy Surveys

Gravitational waves (GWs) from compact binary coalescences have matured into a robust cosmological probe, providing self-calibrated luminosity distance measurements independent of any cosmic distance ladder, hence the term "standard sirens". The binary neutron star merger GW170817 delivered the first such measurement of the Hubble constant, demonstrating that GWs offer a path to precision cosmology with systematics orthogonal to standard cosmological probes. To convert GW distances into cosmological parameters, redshift information is essential. To maximize the scientific potential, the redshift must be obtained from individual galaxies, either by identifying electromagnetic counterparts of GW events (bright sirens) or by statistically associating potential hosts within the GW localization volume (dark sirens). The precision of these redshifts sets the achievable accuracy. Forecasts show that photometric uncertainties degrade cosmological constraints by up to an order of magnitude compared to spectroscopic ones. Wide-field, high-multiplex spectroscopic facilities will therefore be an essential infrastructure for GW cosmology in the 2040s.

astro-ph.IM↗

arXiv2025

Improving Bayesian inference in PTA data analysis: importance nested sampling with Normalizing Flows

We present a detailed study of Bayesian inference workflows for pulsar timing array data with a focus on enhancing efficiency, robustness and speed through the use of normalizing flow-based nested sampling. Building on the Enterprise framework, we integrate the i-nessai sampler and benchmark its performance on realistic, simulated datasets. We analyze its computational scaling and stability, and show that it achieves accurate posteriors and reliable evidence estimates with substantially reduced runtime, by up to three orders of magnitude depending on the dataset configuration, with respect to conventional single-core parallel-tempering MCMC analyses. These results highlight the potential of flow-based nested sampling to accelerate PTA analyses while preserving the quality of the inference.

astro-ph.IM↗

arXiv2025

Cross-correlations of the Cosmic Neutrino Background: HR-DEMNUni simulation analysis

We use the high-resolution HR-DEMNUni simulations to compute cross-correlations of the Cosmic Neutrino Background quantities, like neutrino density, deflection angle, and velocity, with other quantities, like cold dark matter density and effective weak lensing convergence, by accounting for the space-time delay between signals on Earth. We provide this to theoretically illustrate how much can be learned from these cross-correlation signals, once the cosmic neutrino background is detected with instruments in multiple locations. Against a naive expectation of null cross-correlation, we show that the signal is non zero, specially at the largest scales. We also discuss the scenario of co-located cross-correlations between dark matter, weak lensing and a future neutrino-induced photon emission signal. As cross-correlations will be comparable to auto-correlations of the cosmic neutrino background itself and are less affected by cosmic variance and shotnoise, these might be the ones to be measured first. Our predictions thus provide the imprint of what cosmological massive neutrinos, with total mass $\sum{m_ν} \sim 0.1$ eV, should look like from cosmological observations.

astro-ph.CO↗

arXiv2025

The Science of the Einstein Telescope

Einstein Telescope (ET) is the European project for a gravitational-wave (GW) observatory of third-generation. In this paper we present a comprehensive discussion of its science objectives, providing state-of-the-art predictions for the capabilities of ET in both geometries currently under consideration, a single-site triangular configuration or two L-shaped detectors. We discuss the impact that ET will have on domains as broad and diverse as fundamental physics, cosmology, early Universe, astrophysics of compact objects, physics of matter in extreme conditions, and dynamics of stellar collapse. We discuss how the study of extreme astrophysical events will be enhanced by multi-messenger observations. We highlight the ET synergies with ground-based and space-borne GW observatories, including multi-band investigations of the same sources, improved parameter estimation, and complementary information on astrophysical or cosmological mechanisms obtained combining observations from different frequency bands. We present advancements in waveform modeling dedicated to third-generation observatories, along with open tools developed within the ET Collaboration for assessing the scientific potentials of different detector configurations. We finally discuss the data analysis challenges posed by third-generation observatories, which will enable access to large populations of sources and provide unprecedented precision.

gr-qc↗

arXiv2025

Redshift-Space Distortions in Massive Neutrinos Cosmologies

We study the Kaiser formula for biased tracers in massive neutrino cosmologies by comparing its predictions with a large set of N-body simulations. In particular, we examine the ambiguity in the definition of the peculiar velocity contribution at linear level, whether it should be expressed in terms of the total matter velocity field or only the cold-matter component, comprised of cold dark matter and baryons. We revisit and extend previous qualitative studies on the topic with larger statistics and including a full fit of halo power spectrum and halo-matter cross-power spectrum measurements. We find clear evidence that the clustering of halos in redshift space is correctly described assuming that halo velocity is tracing the velocity field of cold-matter. The opposite assumption provides a worse fit to the simulated data and can lead to a spurious running of nuisance parameters in the perturbative galaxy power spectrum model.

astro-ph.CO↗

arXiv2025

Effort: a fast and differentiable emulator for the Effective Field Theory of the Large Scale Structure of the Universe

We present the official release of the EFfective Field theORy surrogaTe (Effort), a novel and efficient emulator designed for the Effective Field Theory of Large-Scale Structure (EFTofLSS). This tool combines state-of-the-art numerical methods and clever preprocessing strategies to achieve exceptional computational performance without sacrificing accuracy. To validate the emulator reliability, we compare Bayesian posteriors sampled using Effort via Hamiltonian MonteCarlo methods to the ones sampled using the widely-used pybird code, via the Metropolis-Hastings sampler. On a large-volume set of simulations, and on the BOSS dataset, the comparison confirms excellent agreement, with deviations compatible with MonteCarlo noise. Looking ahead, Effort is poised to analyze next-generation cosmological datasets and to support joint analyses with complementary tools.

astro-ph.CO↗

arXiv2024

Cosmological forecasts from the combination of Stage-IV photometric galaxy surveys and the magnification from forthcoming GW observatories

In this work we have investigated the synergy between Stage-IV galaxy surveys and future GW observatories for constraining the underlying cosmological model of the Universe, focussing on photometric galaxy clustering, cosmic shear and GW magnification as cosmological probes. We have implemented a Fisher matrix approach for the evaluation of the full $6\times2$pt statistics composed by the angular power spectra of the single probes together with their combination. For our analysis, we have in particular considered dynamical dark energy and massive neutrino scenarios. We have found that the improvement to galaxy survey performance is below 1\%, in the case $\ell^{\rm GW}_{\rm max}=100$ and a luminosity distance error of $σ_{d_L}/d_L=10\%$. However, when extending the analysis to $\ell^{\rm GW}_{\rm max}=1000$, we find that the GW magnification improves the galaxy survey performance on all the cosmological parameters, reducing their errors by $3\%$-$5\%$, when $σ_{d_L}/d_L=10\%$, and by $10\%$-$18\%$ when $σ_{d_L}/d_L=1\%$, especially for $M_ν$, $w_0$ and $w_a$. However, here our analysis is unavoidably optimistic: a much more detailed and realistic approach will be needed, especially by including systematic effects. But we can conclude that, in the case of future gravitational wave observatories the inclusion of the gravitational wave magnification can improve Stage-IV galaxy surveys performance on constraining the underlying cosmological model of the Universe.

astro-ph.CO↗

arXiv2024

The universal multiplicity function: counting halos and voids

We present a novel combination of the excursion-set approach with the peak theory formalism in Lagrangian space and provide accurate predictions for halo and void statistics over a wide range of scales. The set-up is based on an effective moving barrier. Besides deriving the corresponding numerical multiplicity function, we introduce a new analytical formula reaching the percent level agreement with the exact numerical solution obtained via Monte Carlo realizations down to small scales, $\sim 10^{12} h^{-1}\mathrm{M_\odot}$. In the void case, we derive the dependence of the effective moving barrier on the void formation threshold, $δ_{\rm v}$, by comparison against the Lagrangian void size function measured in the Dark Energy and Massive Neutrinos Universe simulations. We discuss the mapping from Lagrangian to Eulerian space for both halos and voids; adopting the spherical symmetry approximation, we obtain a strong agreement at intermediate and large scales. Finally, using the effective moving barrier, we derive Lagrangian void density profiles accurately matching measurements from cosmological simulations, a major achievement towards using void profiles for precision cosmology with the next generation of galaxy surveys.

astro-ph.CO↗

arXiv2024

Neutrino Halo profiles: HR-DEMNUni simulation analysis

Using the high-resolution HR-DEMNUni simulations, we computed neutrino profiles within virialized dark matter haloes. These new high-resolution simulations allowed us to revisit fitting formulas proposed in the literature and provided updated fitting parameters that extend to less massive haloes and lower neutrino masses than previously in the literature, in accordance with new cosmological limits. The trend we observe for low neutrino masses is that, for dark matter halo masses below $\sim 4\times10^{14}$$h^{-1}M_\odot$, the presence of the core becomes weaker and the profile over the whole radius is closer to a simple power law. We also characterized the neutrino density profile dependence on the solid angle within clustered structures: a forward-backward asymmetry larger than 10% was found when comparing the density profiles from neutrinos along the direction of motion of cold dark matter particles within the same halo. In addition, we looked for neutrino wakes around halo centres produced by the peculiar motion of the halo itself. Our results suggest that the wakes effect is observable in haloes with masses greater than $3\times10^{14}$ $h^{-1}M_\odot$ where a mean displacement of $0.06$\hmpc was found.

astro-ph.CO↗