A5023823844- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Scientific Research and Discoveries
- Astronomical Observations and Instrumentation
- Remote Sensing in Agriculture
- Gamma-ray bursts and supernovae
- Black Holes and Theoretical Physics
- Adaptive optics and wavefront sensing
- Blind Source Separation Techniques
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Particle physics theoretical and experimental studies
- Climate variability and models
- Calibration and Measurement Techniques
- Advanced Vision and Imaging
- CCD and CMOS Imaging Sensors
- Advanced Image Processing Techniques
- Data Visualization and Analytics
- Advanced Statistical Methods and Models
- Statistical and numerical algorithms
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
2018-2024
University of Trieste
2021-2024
Institute for Fundamental Physics of the Universe
2020-2024
Trieste Astronomical Observatory
2016-2024
National Institute for Astrophysics
2013-2024
Marconi University
2024
Istituto Nazionale di Fisica Nucleare
2019
Brera Astronomical Observatory
2013-2018
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2015-2017
The Abdus Salam International Centre for Theoretical Physics (ICTP)
2012-2014
Efficient estimators of Fourier-space statistics for large number objects rely on Fast Fourier Transforms (FFTs), which are affected by aliasing from unresolved small scale modes due to the finite FFT grid. Aliasing takes form a sum over images, each them corresponding content displaced increasing multiples sampling frequency These spurious contributions limit accuracy in estimation statistics, and typically ameliorated simultaneously grid size discarding high-frequency modes. This results...
The present spatial distribution of galaxies in the Universe is non-Gaussian, with 40% skewness $50{h}^{\ensuremath{-}1}\text{ }\text{ }\mathrm{Mpc}$ spheres, and remarkably little known about information encoded it cosmological parameters beyond power spectrum. In this work we an attempt to bridge gap by studying bispectrum, paying particular attention a joint analysis spectrum their combination CMB data. We address covariance properties bispectrum including effects beat coupling that lead...
The greatest challenge in the interpretation of galaxy clustering data from any surveys is bias. Using a simple Fisher matrix analysis, we show that bispectrum provides an excellent determination linear and non-linear bias parameters intermediate high-z galaxies, when all measurable triangle configurations down to mildly scales, where perturbation theory still valid, are included. also powerful probe primordial non-Gaussianity. planned at z>2 should yield constraints on non-Gaussian...
We consider primordial non-Gaussianity due to quadratic corrections in the gravitational potential parametrized by a nonlinear coupling parameter ${f}_{\mathrm{NL}}.$ study constraints on ${f}_{\mathrm{NL}}$ from measurements of galaxy bispectrum redshift surveys. Using estimates for idealized survey geometries 2dF and SDSS surveys realistic ones mock catalogs, we show that it is possible probe $|{f}_{\mathrm{NL}}|\ensuremath{\simeq}100,$ after marginalization over bias parameters. apply our...
We analyse the clustering features of Large Scale Structures (LSS) in presence massive neutrinos, employing a set large-volume, high-resolution cosmological N-body simulations, where neutrinos are treated as separate collisionless particles. The volume 8 h-3 Gpc3, combined with resolution about 8×1010h-1M⊚ for cold dark matter (CDM) component, represents significant improvement over previous simulations neutrino cosmologies. In this work we focus, first place, on analysis nonlinear effects...
By using a suite of large box-size N-body simulations that incorporate massive neutrinos as an extra set particles, we investigate the impact neutrino masses on spatial distribution dark matter haloes and galaxies. We compute bias between overall cold distributions statistical tools such power spectrum two-point correlation function. Overall find scale-dependent scales for cosmologies with neutrinos. However, our results indicate scale-dependence in is reduced if latter computed respect to...
The most direct probe of non-Gaussian initial conditions has come from bispectrum measurements temperature fluctuations in the Cosmic Microwave Background and matter galaxy distribution at large scales. Such estimators are expected to continue provide best constraints on parameters future observations. We review compare theoretical observational problems, current results prospects for detection a non-vanishing primordial component large-scale structure, relation specific predictions...
We use a large suite of N-body simulations to study departures from universality in halo abundances and clustering cosmologies with non-vanishing neutrino masses. To this end, we how the mass function bias factors depend on scaling variable σ2(M,z), variance initial matter fluctuation field, rather than M redshift z themselves. show that using cold dark total i.e., σ2cdm(M,z) σ2m(M,z), yields more universal results. Analysis similar conclusions: when large-scale is defined respect power...
We present a new parallel implementation of the PINpointing Orbit Crossing-Collapsed HIerarchical Objects (PINOCCHIO) algorithm, quick tool, based on Lagrangian Perturbation Theory, for hierarchical build-up Dark Matter halos in cosmological volumes. To assess its ability to predict halo correlations large scales, we compare results with those an N-body simulation 3 Gpc/h box sampled 2048^3 particles taken from MICE suite, matching same seeds initial conditions. Thanks FFTW libraries and...
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 Fourier space. However, realizing the full potential this dataset is contingent upon having both accurate theoretical models optimized analysis methods. Focusing local model PNG, parameterized by $f_{\rm NL}$, we perform a Monte-Carlo Markov Chain confront perturbation theory predictions halo power spectrum...
We present the analysis of halo bispectrum in redshift-space terms its multipoles, monopole, quadrupole and hexadecapole, measured from a large set simulations. fit such measurements with tree-level model perturbation theory that depends on linear nonlinear bias parameters as well growth rate $f$ density fluctuations. The likelihood takes advantage very mock catalogs, enabling robust estimation covariance properties for all multipoles. compare numerical estimate matrix to Gaussian prediction...
A new and powerful probe of the origin evolution structures in Universe has emerged been actively developed over last decade. In coming decade, non-Gaussianity, i.e., study non-Gaussian contributions to correlations cosmological fluctuations, will become an important both early late Universe. Specifically, it play a leading role furthering our understanding two fundamental aspects cosmology astrophysics: (i) physics very universe that created primordial seeds for large-scale structures, (ii)...
The primordial non-Gaussian parameter fNL has been shown to be scale-dependent in several models of inflation with a variable speed sound, such as Dirac-Born-Infeld (DBI) models. We perform Fisher matrix analysis the bispectra temperature and polarization Cosmic Microwave Background (CMB) radiation derive expected constraints on nNG that quantifies running fNL(k) for current future CMB missions. find information alone, event significant detection component, corresponding = 50 local model 100...
We use a suite of N-body simulations that incorporate massive neutrinos as an extra-set particles to investigate their effect on the halo mass function. show for cosmologies with function dark matter haloes selected using spherical overdensity (SO) criterion is well reproduced by fitting formula Tinker et al. (2008) once cold power spectrum considered instead total power, it usually done. The differences between two implementations, i.e. $P_{\rm cdm}(k)$ m}(k)$, are more pronounced large...
The set-up of the initial conditions in cosmological N-body simulations is usually implemented by rescaling desired low-redshift linear power spectrum to required starting redshift consistently with Newtonian evolution simulation. implementation this practical solution requires more care context massive neutrino cosmologies, mainly because non-trivial scale-dependence growth that characterises these models. In work we consider a simple two-fluid, approximation for cold dark matter and...
This paper is the first in a set that analyses covariance matrices of clustering statistics obtained from several approximate methods for gravitational structure formation. We focus here on anisotropic two-point correlation function measurements. Our comparison includes seven methods, which can be divided into three categories: predictive follow evolution linear density field deterministically (ICE-COLA, Peak Patch, and Pinocchio), require calibration with N-body simulations (Patchy...
ABSTRACT We study the accuracy of several approximate methods for gravitational dynamics in terms halo power spectrum multipoles and their estimated covariance matrix. propagate differences covariances into parameter constraints related to growth rate structure, Alcock–Paczynski distortions, biasing. consider seven three broad categories: algorithms that solve density evolution deterministically using Lagrangian trajectories (ICE–COLA, pinocchio, peakpatch), rely on assignment schemes dark...
We compare the measurements of bispectrum and estimate its covariance obtained from a set different methods for efficient generation approximate dark matter halo catalogs to same quantities full N-body simulations. To this purpose we employ large three-hundred realisations cosmology each method, run with matching initial conditions in order reduce contribution cosmic variance comparison. In addition, how error on cosmological parameters such as linear nonlinear bias depends method used...
ABSTRACT Luminous matter produces very energetic events, such as active galactic nuclei and supernova explosions, that significantly affect the internal regions of galaxy clusters. Although current uncertainty in effect baryonic physics on cluster statistics is subdominant compared to other systematics, picture likely change soon amount high-quality data growing fast, urging community keep theoretical systematic uncertainties below ever-growing statistical precision. In this paper, we study...
The forthcoming generation of galaxy redshift surveys will sample the large-scale structure Universe over unprecedented volumes with high-density tracers. This advancement make robust measurements three-point clustering statistics possible. In preparation for this improvement, we investigate how several methodological choices can influence inferences based on bispectrum about bias and shot noise. We first measure real-space dark-matter haloes extracted from 298 N-body simulations covering a...
Euclid's photometric galaxy cluster survey has the potential to be a very competitive cosmological probe. The main probe with observations of clusters is their number count, within which halo mass function (HMF) key theoretical quantity. We present new calibration analytic HMF, at level accuracy and precision required for uncertainty in this quantity subdominant respect other sources recovering parameters from Euclid counts. Our model calibrated against suite N-body simulations using...
Aims. We validate a semi-analytical model for the covariance of real-space two-point correlation function galaxy clusters. Methods. Using 1000 PINOCCHIO light cones mimicking expected Euclid sample clusters, we calibrated simple to accurately describe clustering covariance. Then, used this quantify likelihood-analysis response variations in covariance, and investigated impact cosmology-dependent matrix at level statistics survey Results. find that Gaussian with Poissonian shot-noise does not...
We derive the expressions for one-loop corrections in cosmological, Eulerian, perturbation theory to matter bispectrum and galaxy bispectrum, assuming local bias, presence of non-Gaussian initial conditions. compute them explicitly particular case nonvanishing trispectrum model a alone equilateral primordial non-Gaussianity. While contribution values compatible with cosmic microwave background observations is dominant over component due gravitational instability at large scales, perturbative...
We present measurements of the dark matter bispectrum in N-body simulations with non-Gaussian initial conditions local kind for a large variety triangular configurations and compare them predictions from Eulerian Perturbation Theory up to one-loop corrections. find that effects primordial non-Gaussianity at scales, when compared Theory, are well described by component bispectrum, linearly extrapolated redshift interest. In addition, we that, f_NL=100, nonlinear corrections due order ~3, 4%...
We measure the two-point spatial correlation function for clusters selected from photometric MaxBCG galaxy cluster catalog Sloan Digital Sky Survey (SDSS). evaluate several samples using different cuts in richness. Fitting results to power laws, ξcc(r) = (r/R0)−γ, estimated length R0 as a of richness is broadly consistent with previous observations and expectations N-body simulations. study how linear bias parameter scales compare our theoretical predictions. Since these measurements extend...