Publications (43)
Understanding and inverse design of implicit bias in stochastic learning: a geometric perspective
Nicola Aladrah, Emanuele Ballarin, Matteo Biagetti +3
A key challenge in machine learning is to explain how learning dynamics select among the many solutions that achieve identical loss values in overparameterized models - a phenomeno…
Inflation: Theory and Observations
Ana Achúcarro, Matteo Biagetti, Matteo Braglia +19
Cosmic inflation provides a window to the highest energy densities accessible in nature, far beyond those achievable in any realistic terrestrial experiment. Theoretical insights i…
The reach of next-to-leading-order perturbation theory for the matter bispectrum
Davit Alkhanishvili, Cristiano Porciani, Emiliano Sefusatti +4
We provide a comparison between the matter bispectrum derived with different flavours of perturbation theory at next-to-leading order and measurements from an unprecedentedly large…
Inflation and Dark Energy from spectroscopy at
Simone Ferraro, Michael J. Wilson, Muntazir Abidi +140
The expansion of the Universe is understood to have accelerated during two epochs: in its very first moments during a period of Inflation and much more recently, at , when D…
Cosmology with Persistent Homology: a Fisher Forecast
Jacky H. T. Yip, Matteo Biagetti, Alex Cole +2
Persistent homology naturally addresses the multi-scale topological characteristics of the large-scale structure as a distribution of clusters, loops, and voids. We apply this tool…
Primordial Non-Gaussianity
P. Daniel Meerburg, Daniel Green, Muntazir Abidi +175
Our current understanding of the Universe is established through the pristine measurements of structure in the cosmic microwave background (CMB) and the distribution and shapes of…
Measuring nonlocal Lagrangian peak bias
Matteo Biagetti, Kwan Chuen Chan, Vincent Desjacques +1
We investigate nonlocal Lagrangian bias contributions involving gradients of the linear density field, for which we have predictions from the excursion set peak formalism. We begin…
Enhancing Inflationary Tensor Modes through Spectator Fields
Matteo Biagetti, Matteo Fasiello, Antonio Riotto
We show that a large contribution to tensor modes during inflation can be generated by a spectator scalar field with speed of sound lower than unity.
Abundance of peaks and dips in three-dimensional mass and halo density fields: a test for cosmology
Adi Nusser, Matteo Biagetti, Vincent Desjacques
Using cosmological N-body simulations, we study the abundance of local maxima (peaks) and minima (dips) identified in the smoothed distribution of halos and dark matter (DM) on sca…
TopoFisher: Learning Topological Summary Statistics by Maximizing Fisher Information
Matteo Biagetti, Mathieu Carrière, Francesco Conti +3
Persistence diagrams provide stable, interpretable summaries of geometric and topological structure and are useful for simulation-based inference when low-order statistics miss key…
Topological Echoes of Primordial Physics in the Universe at Large Scales
Alex Cole, Matteo Biagetti, Gary Shiu
We present a pipeline for characterizing and constraining initial conditions in cosmology via persistent homology. The cosmological observable of interest is the cosmic web of larg…
On the halo velocity bias
Matteo Biagetti, Vincent Desjacques, Alex Kehagias +1
It has been recently shown that any halo velocity bias present in the initial conditions does not decay to unity, in agreement with predictions from peak theory. However, this is a…
The Geometry of Tokens in Internal Representations of Large Language Models
Karthik Viswanathan, Yuri Gardinazzi, Giada Panerai +2
We investigate the relationship between the geometry of token embeddings and their role in the next token prediction within transformer models. An important aspect of this connecti…
Possible Signatures of Inflationary Particle Content: Spin-2 Fields
Matteo Biagetti, Emanuela Dimastrogiovanni, Matteo Fasiello
We study the imprints of a massive spin-2 field on inflationary observables, and in particular on the breaking of consistency relations. In this setup, the minimal inflationary fie…
Constraint of Void Bias on Primordial non-Gaussianity
Kwan Chuen Chan, Nico Hamaus, Matteo Biagetti
We study the large-scale bias parameter of cosmic voids with primordial non-Gaussian (PNG) initial conditions of the local type. In this scenario, the dark matter halo bias exhibit…
Primordial Non-Gaussianity from Biased Tracers: Likelihood Analysis of Real-Space Power Spectrum and Bispectrum
Azadeh Moradinezhad Dizgah, Matteo Biagetti, Emiliano Sefusatti +2
Upcoming galaxy redshift surveys promise to significantly improve current limits on primordial non-Gaussianity (PNG) through measurements of 2- and 3-point correlation functions in…
Zigzag Persistence of Neural Responses to Time-Varying Stimuli
Yuri Gardinazzi, Alessio Ansuini, Eugenio Piasini +2
We use topological data analysis to study neural population activity in the Sensorium 2023 dataset, which records responses from thousands of mouse visual cortex neurons to diverse…
The Hunt for Primordial Interactions in the Large Scale Structures of the Universe
Matteo Biagetti
The understanding of the primordial mechanism that seeded the cosmic structures we observe today in the sky is one of the major goals in cosmology. The leading paradigm for such a…
Primordial Gravitational Waves from Galaxy Intrinsic Alignments
Matteo Biagetti, Giorgio Orlando
Galaxy shapes have been observed to align with external tidal fields generated by the large-scale structures of the Universe. While the main source for these tidal fields is provid…
Primordial Black Holes from Inflation and Quantum Diffusion
Matteo Biagetti, Gabriele Franciolini, Alex Kehagias +1
Primordial black holes as dark matter may be generated in single-field models of inflation thanks to the enhancement at small scales of the comoving curvature perturbation. This me…
Fitting covariance matrix models to simulations
Alessandra Fumagalli, Matteo Biagetti, Alexandro Saro +4
Data analysis in cosmology requires reliable covariance matrices. Covariance matrices derived from numerical simulations often require a very large number of realizations to be acc…
What We Can Learn from the Running of the Spectral Index if no Tensors are Detected in the Cosmic Microwave Background Anisotropy
Matteo Biagetti, Alex Kehagias, Antonio Riotto
In this paper we operate under the assumption that no tensors from inflation will be measured in the future by the dedicated experiments and argue that, while for single-field slow…
Squeezing the halo bispectrum: a test of bias models
Azadeh Moradinezhad Dizgah, Kwan Chuen Chan, Jorge Noreña +2
We study the halo-matter cross bispectrum in the presence of primordial non-Gaussianity of the local type. We restrict ourselves to the squeezed limit, for which the calculation ar…
Persistent Topological Features in Large Language Models
Yuri Gardinazzi, Karthik Viswanathan, Giada Panerai +3
Understanding the decision-making processes of large language models is critical given their widespread applications. To achieve this, we aim to connect a formal mathematical frame…
Primordial Features from Linear to Nonlinear Scales
Florian Beutler, Matteo Biagetti, Daniel Green +2
Sharp features in the primordial power spectrum are a powerful window into the inflationary epoch. To date, the cosmic microwave background (CMB) has offered the most sensitive ave…
The Halo Boltzmann Equation
Matteo Biagetti, Vincent Desjacques, Alex Kehagias +2
Dark matter halos are the building blocks of the universe as they host galaxies and clusters. The knowledge of the clustering properties of halos is therefore essential for the und…
Non-local halo bias with and without massive neutrinos
Matteo Biagetti, Vincent Desjacques, Alex Kehagias +1
Understanding the biasing between the clustering properties of halos and the underlying dark matter distribution is important for extracting cosmological information from ongoing a…
Ultraviolet background fluctuations with clustered sources
Vincent Desjacques, Azadeh Moradinezhad Dizgah, Matteo Biagetti
We develop a count-in-cells approach to the distribution of ultraviolet background fluctuations that includes source clustering. We demonstrate that an exact expression can be obta…
The Persistence of Large Scale Structures I: Primordial non-Gaussianity
Matteo Biagetti, Alex Cole, Gary Shiu
We develop an analysis pipeline for characterizing the topology of large scale structure and extracting cosmological constraints based on persistent homology. Persistent homology i…
Scale-dependent bias from an inflationary bispectrum: the effect of a stochastic moving barrier
Matteo Biagetti, Vincent Desjacques
With the advent of large scale galaxy surveys, constraints on primordial non-Gaussianity (PNG) are expected to reach . In order to fully exploit the p…
The Formation Probability of Primordial Black Holes
Matteo Biagetti, Valerio De Luca, Gabriele Franciolini +2
We calculate the exact formation probability of primordial black holes generated during the collapse at horizon re-entry of large fluctuations produced during inflation, such as th…
Primordial non-Gaussianity and non-Gaussian Covariance
Thomas Flöss, Matteo Biagetti, P. Daniel Meerburg
In the pursuit of primordial non-Gaussianities, we hope to access smaller scales across larger comoving volumes. At low redshift, the search for primordial non-Gaussianities is hin…
Testing Multi-Field Inflation with Galaxy Bias
Matteo Biagetti, Vincent Desjacques, Antonio Riotto
Multi-field models of inflation predict an inequality between the amplitude tauNL of the collapsed limit of the four-point correlator of the primordial curvature perturbation and t…
Testing the Running of non-Gaussianity through the CMB mu-distortion and the Halo Bias
Matteo Biagetti, Hideki Perrier, Antonio Riotto +1
The primordial non-Gaussianity parameters fNL and tauNL may be scale-dependent. We investigate the capability of future measurements of the CMB mu-distortion, which is very sensiti…
Verifying the consistency relation for the scale-dependent bias from local primordial non-Gaussianity
Matteo Biagetti, Titouan Lazeyras, Tobias Baldauf +2
We measure the large-scale bias of dark matter halos in simulations with non-Gaussian initial conditions of the local type, and compare this bias to the response of the mass functi…
Measurement of Void Bias Using Separate Universe Simulations
Kwan Chuen Chan, Yin Li, Matteo Biagetti +1
Cosmic voids are biased tracers of the large-scale structure of the universe. Separate universe simulations (SUS) enable accurate measurements of this biasing relation by implement…
Symmetries of Vector Perturbations during the de Sitter Epoch
Matteo Biagetti, Alex Kehagias, Enrico Morgante +2
We analyze the class of models where a suitable coupling between the inflaton field and the vector field gives rise to scale-invariant vector perturbations. We exploit the fact tha…
Bispectrum-window convolution via Hankel transform
Kevin Pardede, Federico Rizzo, Matteo Biagetti +3
We present a method to perform the exact convolution of the model prediction for bispectrum multipoles in redshift space with the survey window function. We extend a widely applied…
A Model for the Squeezed Bispectrum in the Non-Linear Regime
Matteo Biagetti, Juan Calles, Lina Castiblanco +2
We present a model for the squeezed dark matter bispectrum, where the short modes are deep in the non-linear regime. We exploit the consistency relations for large-scale structures…
On the range of validity of perturbative models for galaxy clustering and its uncertainty
Giosuè Gambardella, Matteo Biagetti, Chiara Moretti +1
We explore the reach of analytical models at one-loop in Perturbation Theory (PT) to accurately describe measurements of the galaxy power spectrum from numerical simulations in red…
Gravitational Waves and Scalar Perturbations from Spectator Fields
Matteo Biagetti, Emanuela Dimastrogiovanni, Matteo Fasiello +1
The most conventional mechanism for gravitational waves (gw) production during inflation is the amplification of vacuum metric fluctuations. In this case the gw production can be u…
Fisher Forecasts for Primordial non-Gaussianity from Persistent Homology
Matteo Biagetti, Juan Calles, Lina Castiblanco +2
We study the information content of summary statistics built from the multi-scale topology of large-scale structures on primordial non-Gaussianity of the local and equilateral type…
The Covariance of Squeezed Bispectrum Configurations
Matteo Biagetti, Lina Castiblanco, Jorge Noreña +1
We measure the halo bispectrum covariance in a large set of N-body simulations and compare it with theoretical expectations. We find a large correlation among (even mildly) squeeze…