arXiv subjects

Fabio Iocco

Publications and source records attributed to Fabio Iocco.

At least 19 recordsLinked to original sources

arXiv2026

Primordial Black Hole interpretation of the sub-solar merger event S251112cm

The LIGO-Virgo-KAGRA (LVK) candidate event S251112cm suggests the presence of at least one compact object with sub-solar masses. Since such objects cannot be produced through standard stellar evolution, this observation provides a potential indication of non-standard formation channels. Primordial black holes (PBHs), formed from the collapse of primordial density fluctuations in the early Universe, are a well-motivated candidate. We investigate the interpretation of S251112cm as the merger of two PBHs with masses in the range 0.1-1$\,M_\odot$. Combining analytic estimates of the PBH merger rate with current observational constraints on their abundance and the sensitivity of LVK searches, we compute the probability of observing such an event. Within a relaxed constraint scenario, the probability reaches unity in the range $M_{\rm PBH} \sim 0.5$-$1\,M_\odot$, while it remains sizable, $\sim \mathcal{O}(0.5)$, in more conservative scenarios and at lower masses. Our results show that a PBH interpretation of S251112cm is viable within current bounds. Owing to the dependence of our results on astrophysical uncertainties, such as those affecting the constraints on the abundance of PBHs, they cannot be regarded as conclusive with respect to the nature of the detected event. At the same time, our analysis highlights the potential of sub-solar gravitational wave events as a probe of PBHs and their contribution to dark matter.

astro-ph.CO↗

arXiv2025

Dark Matter profiles of "in silico" galaxies: deep learning inference

Machine learning has the potential to improve the reconstruction of the dark matter profile of galaxies with respect to traditional methods, like rotation curves. We demonstrate on the simulation suite Illustris-TNG that a steerable equivariant convolutional neural network (CNN) is able to infer the dark matter profiles within and around individual galaxies from photometric and interferometric data, improving on a standard CNN. Within the in silico environment of the simulations, our architecture is able to capture the dark matter distribution within galaxies without a parametrization of the profile. We perform an interpretability analysis to understand the internal mechanisms of the trained model and the most important data features used to estimate the dark matter profiles. The equivariant CNN recovers the dark matter profile of galaxies within the stellar mass range $[10^{10} - 10^{12} ]$ $M_{\odot}$ with excellent precision and accuracy: the mean squared error is reduced by a factor of ~ 3 from its value under the training distribution, demonstrating that the network has learnt from the data features. While this holds within the controlled 'in silico' environment of the simulation, we argue that few additional steps are needed before this method can be reliably applied to galaxies in the real field observations.

astro-ph.GA↗

arXiv2025

A strike of luck: could the KM3-230213A event be caused by an evaporating primordial black hole?

We investigate whether the ultra high energy neutrino inferred by the recent KM3NeT observation could have originated from an evaporating black hole. Given the characteristics of black hole (BH) evaporation mechanism, any object capable of producing particles in the energy range of the detected event (around 100-800 PeV) must have a mass below 10^7 g. No known astrophysical mechanism can generate black holes of such low mass, leaving primordial black holes (PBHs)-potentially formed at the end of cosmic inflation-as the only viable candidates. Black holes with masses below 10^7 g have lifetimes shorter than 10^-5 seconds, meaning PBHs in this mass range should have fully evaporated by now. However, recent studies suggest that quantum effects, collectively referred to as the "memory burden", may slow down black hole evaporation, potentially extending the lifetimes of low-mass PBHs to timescales comparable to or exceeding the Hubble time. We systematically explore the parameter space of memory-burdened PBHs, assuming that they constitute a fraction of the dark matter (f-PBH) within current constraints, and identify viable regions that could explain the KM3-230213A event. We further predict the occurrence rate of similar events and find that KM3NeT's current configuration could test this scenario within a few years.

astro-ph.HE↗

arXiv2024

Light burden of memory: Constraining primordial black holes with high-energy neutrinos

Recent studies point out that quantum effects, referred to as "memory burden", may slow down the evaporation of black holes. As a result, a population of light primordial black holes could potentially survive to the present day, thus contributing to the energy density of dark matter. In this work, we focus on light primordial black holes with masses $M_{\rm PBH} \lesssim 10^{9}~{\rm g}$ that, due to the memory burden effect, are currently evaporating, emitting high-energy particles, among which neutrinos, in the local Universe. Analyzing the latest IceCube data, we place novel constraints on the combined parameter space of primordial black holes and the memory burden effect. We also study the projected reach of future neutrino telescopes such as IceCube-Gen2 and GRAND. We find that the neutrino observations are crucial to probe scenarios with highly-suppressed evaporation and light masses for primordial black holes.

astro-ph.HE↗

arXiv2024

Compatibility of JWST results with exotic halos

The James Webb Space Telescope (JWST) is unveiling astounding results about the first few hundred million years of life of the Universe, delivering images of galaxies at very high redshifts. Here, we develop a UV luminosity function model for high-redshift galaxies, considering parameters such as the stellar formation rate, dust extinction, and halo mass function. Calibration of this luminosity function model using UV luminosity data at redshifts z = 4-7 yields optimal parameter values. Testing the model against data at higher redshifts reveals successful accommodation of the data at z = 8-9, but challenges emerge at z~13. Our findings suggest a negligible role of dust extinction at the highest redshifts, prompting a modification of the stellar formation rate to incorporate a larger fraction of luminous objects per massive halo, consistently with similar recent studies. This effect could be attributed to mundane explanations such as unknown evolution of standard astrophysics at high redshift or to the existence of exotic objects at high redshift. We comment on this latter possibility.

astro-ph.CO↗

arXiv2024

Constraining the primordial black hole abundance through Big-Bang nucleosynthesis

We investigate the scenario in which primordial black holes (PBHs) with masses Mpbh < 10^9 g undergo Hawking evaporation, around the Big-Bang nucleosynthesis (BBN) epoch. The evaporation process modifies the Universe's expansion rate and the baryon-to-photon ratio, leading to an alteration of the primordial abundance of light nuclei. We present numerical solutions for the set of equations describing this physics, considering different values of PBH masses and abundances at their formation, showing how their evaporation impacts the abundances of light nuclei, obtained by incorporating the non-standard Hubble rate and baryon-to-photon ratio into the BBN code PArthENoPE. The results are then used to place upper bounds for the PBH relative abundance at formation in the range 10^8 g < Mpbh < 10^9 g, providing the strongest constraints existing to-date in this mass range.

astro-ph.CO↗

arXiv2023

Determining the Dark Matter distribution in galaxies with Deep Learning

We present a novel method to infer the Dark Matter (DM) content and spatial distribution within galaxies, based on convolutional neural networks trained within state-of-the-art hydrodynamical simulations (Illustris TNG100). The framework we have developed is capable of inferring the DM mass distribution within galaxies of mass $~10^{11}-10^{13}M_{\odot}$ with very high performance from the gravitationally baryon dominated internal regions to the DM-rich, baryon-depleted outskirts of the galaxies. With respect to traditional methods, the one presented here also possesses the advantages of not relying on a pre-assigned shape for the DM distribution, to be applicable to galaxies not necessarily in isolation, and to perform very well even in the absence of spectroscopic observations

astro-ph.GA↗

arXiv2023

Prospects for annihilating dark matter from M31 and M33 observations with the Cherenkov Telescope Array

M31 and M33 are the closest spiral galaxies and the largest members (together with the Milky Way) of the Local group, which makes them interesting targets for indirect dark matter searches. In this paper, we present studies of the expected sensitivity of the Cherenkov Telescope Array (CTA) to an annihilation signal from weakly interacting massive particles from M31 and M33. We show that a 100 h long observation campaign will allow CTA to probe annihilation cross-sections up to $\langleσ\upsilon\rangle\approx 5\cdot10^{-25}$ cm$^{3}$s$^{-1}$ for the $τ^{+}τ^{-}$ annihilation channel (for M31, at a DM mass of 0.3 TeV), improving the current limits derived by HAWC by up to an order of magnitude. We present an estimate of the expected CTA sensitivity, by also taking into account the contributions of the astrophysical background and other possible sources of systematic uncertainty. We also show that CTA might be able to detect the extended emission from the bulge of M31, detected at lower energies by the Fermi/LAT.

astro-ph.HE↗

arXiv2022

Axions from Neutron Star Mergers

Axion-like particles (ALP) can in principle be produced in very hot and dense astrophysical environments, escape from the extreme object where such conditions are met, and then be converted in gamma--rays in the magnetic fields intervening between the event and the Earth. This process potentially offers a new window on both the physics of the axions, and the inner working of the astrophysical objects where they are produced. Interestingly, while this process has been studied for core--collapse supernovae and other extreme astrophysical events, no estimate exists for Neutron Star Mergers, objects recently identified through the detection of gravitational waves. In this work we study the production of ALPs in neutron star mergers, finding that for a large region of the ALP parameter space its magnitude at the source is such to produce a sizable gamma-ray signal at Earth. We show detection forecasts for such events placed in nearby galaxies, finding that they are potentially observable with the Fermi--LAT, thus opening a new window into both the astrophysics of these cataclysmic events, and of new particles beyond the standard model.

astro-ph.HE↗

arXiv2021

Testing gravity with the Milky Way: Yukawa potential

We test a Yukawa correction to the Newtonian potential, making use of our own Galaxy - the Milky Way - as a testbed. We include as free parameter the Yukawa strength and range and the dark matter profile parameters, and compare several morphologies for the bulge, gas, and disk components, also using Bayesian model selection criteria. We employ up-to-date datasets for both the visible (baryonic) component of the Milky Way, and for the tracers of the gravitational potential (the Rotation Curve). We find that the data are consistent with the Newtonian potential, and constrain the Yukawa coupling $β$ to be negative and $λ$ to range along the curve $λ= a|β|^{c}$ with $a = (0.77 \pm 0.06)$ kpc and $c = -0.503\substack{+0.016 \\ -0.019}$.

astro-ph.GA↗

arXiv2021

Uncertainties in the Galactic dark matter distribution: an update

We present here a quantitative, accurate estimate of the impact of uncertainties of astrophysical nature on the determination of the dark matter distribution within our Galaxy, the Milky Way. Based on an update of a previous analysis, this work is motivated by recent new determinations of astrophysical quantities of relevance -- such as the Galactic parameters (R0,V0) -- from the GRAVITY collaboration and the GAIA satellite, respectively. We find that even with these state-of-the-art determination and a range of uncertainties -- both statistical and systematic -- much narrowed with respect to previous work, the uncertainties on the dark matter distribution and their impact on searches of physics beyond the standard model stays sizable.

astro-ph.GA↗

arXiv2020

A robust estimate of the Milky Way mass from rotation curve data

We present a new estimate of the mass of the Milky Way, inferred via a Bayesian approach by making use of tracers of the circular velocity in the disk plane and stars in the stellar halo, as from the publicly available {\tt galkin} compilation. We use the rotation curve method to determine the dark matter distribution and total mass under different assumptions for the dark matter profile, while the total stellar mass is constrained by surface stellar density and microlensing measurements. We also include uncertainties on the baryonic morphology via Bayesian model averaging, thus converting a potential source of systematic error into a more manageable statistical uncertainty. We evaluate the robustness of our result against various possible systematics, including rotation curve data selection, uncertainty on the Sun's velocity $V_0$, dependence on the dark matter profile assumptions, and choice of priors. We find the Milky Way's dark matter virial mass to be $\log_{10}M_{200}^{\rm DM}/ {\rm M_\odot} = 11.92^{+0.06}_{-0.05}{\rm(stat)}\pm{0.28}\pm0.27{\rm(syst)}$ ($M_{200}^{\rm DM}=8.3^{+1.2}_{-0.9}{\rm(stat)}\times10^{11}\,{\rm M_\odot}$). We also apply our framework to Gaia DR2 rotation curve data and find good statistical agreement with the above results.

astro-ph.GA↗

arXiv2019

Bayesian reconstruction of the Milky Way dark matter distribution

We develop a novel Bayesian methodology aimed at reliably and precisely inferring the distribution of dark matter within the Milky Way using rotation curve data. We identify a subset of the available rotation curve tracers that are mutually consistent with each other, thus eliminating data sets that might suffer from systematic bias. We investigate three different models for the mass distribution of the luminous (baryonic) component that bracket the range of likely morphologies. We demonstrate the statistical performance of our method on simulated data in terms of coverage, fractional distance, and mean squared error. Applying it to Milky Way data we measure the local dark matter density at the solar circle $ρ_0$ to be $ρ_0 = 0.43\pm 0.02(\rm{stat})\pm0.01(\rm{sys})$ GeV/cm$^3$, with an accuracy $\sim$ 6%. This result is robust to the assumed baryonic morphology. The scale radius and inner slope of the dark matter profile are degenerate and cannot be individually determined with high accuracy. We show that these results are robust to several possible residual systematic errors in the rotation curve data.

astro-ph.GA↗

arXiv2019

Handling the Uncertainties in the Galactic Dark Matter Distribution for Particle Dark Matter Searches

In this work we characterize the distribution of Dark Matter (DM) in the Milky Way (MW), and its uncertainties, adopting the well known "Rotation Curve" method. We perform a full marginalization over the uncertainties of the Galactic Parameters and over the lack of knowledge on the morphology of the baryonic components of the Galaxy. The local DM density rho0 is constrained to the range 0.3 - 0.8 GeV/cm3 at the 2 sigma level, and has a strong positive correlation to R0, the local distance from the Galactic Center (GC). The not well-known value of R0 is thus, at the moment, a major limitation in determining rho0. Similarly, we find that the inner slope of the DM profile, gamma, is very weakly constrained, showing no preference for a cored profile (gamma~0) or a cuspy one (gamma~[1.0,1.4]). Some combination of parameters can be, however, strongly constrained. For example the often used standard rho0=0.3 GeV/cm3, R0=8.5 kpc is excluded at more than 4 sigma. We release the full likelihood of our analysis in a tabular form over a multidimensional grid in the parameters characterizing the DM distribution, namely the scale radius Rs, the scale density rhos, the inner slope of the profile gamma, and R0. The likelihood can be used to include the effect of the DM distribution uncertainty on the results of searches for an indirect DM signal in gamma-rays or neutrinos, from the GC, or the Halo region surrounding it. As one example, we study the case of the GC excess in gamma rays. Further applications of our tabulated uncertainties in the DM distribution involve local DM searches, like direct detection and anti-matter observations, or global fits combining local and GC searches.

astro-ph.GA↗

arXiv2018

Testing MOG theory in the Milky Way

We perform a test of John Moffat's Modified Gravity theory (MOG) within the Milky Way, adopting the well known "Rotation Curve" method. We use the dynamics of observed tracers within the disk to determine the gravitational potential as a function of galactocentric distance, and compare that with the potential that is expected to be generated by the visible component only (stars and gas) under different "flavors" of the MOG theory, making use of a state-of-the-art setup for both the observed tracers and baryonic morphology. Our analysis shows that in both the original and the modified version (considering a self-consistent evaluation of the Milky Way mass), the theory fails to reproduce the observed rotation curve. We conclude that in none of its present formulation, the MOG theory is able to explain the observed Rotation Curve of the Milky Way.

astro-ph.GA↗

arXiv2018

Statistical challenges in the search for dark matter

The search for the particle nature of dark matter has given rise to a number of experimental, theoretical and statistical challenges. Here, we report on a number of these statistical challenges and new techniques to address them, as discussed in the DMStat workshop held Feb 26 - Mar 3 2018 at the Banff International Research Station for Mathematical Innovation and Discovery (BIRS) in Banff, Alberta.

hep-ph↗

arXiv2018

Interplay of the LHC and non-LHC Dark Matter searches in the Effective Field Theory approach

We present accurate and up-to-date constraints on the complete set of dimension five and six operators with scalar, fermion and vector Dark Matter (DM). We find limits using LHC mono-jet data, spin inde- pendent and spin dependent direct searches, relic density and CMB, and show the interplay between high and low energy data in setting bounds on the parameter space. In order to properly compare data taken at different energies, we take into account the effect of the running and mixing of operators. We also take into account the local density uncertainties affecting direct detection data, and apply EFT validity criteria related to the cut on the invariant mass of DM pair production at the LHC, which turns out to be especially important for the case of vector DM. Finally, we estimate the potential of the future LHC runs to probe DM parameter space.

hep-ph↗

arXiv2018

Particle Dark Matter Constraints: the Effect of Galactic Uncertainties

Collider, space, and Earth based experiments are now able to probe several extensions of the Standard Model of particle physics which provide viable dark matter candidates. Direct and indirect dark matter searches rely on inputs of astrophysical nature, such as the local dark matter density or the shape of the dark matter profile in the target in object. The determination of these quantities is highly affected by astrophysical uncertainties. The latter, especially those for our own Galaxy, are ill-known, and often not fully accounted for when analyzing the phenomenology of particle physics models. In this paper we present a systematic, quantitative estimate of how astrophysical uncertainties on Galactic quantities (such as the local galactocentric distance, circular velocity, or the morphology of the stellar disk and bulge) propagate to the determination of the phenomenology of particle physics models, thus eventually affecting the determination of new physics parameters. We present results in the context of two specific extensions of the Standard Model (the Singlet Scalar and the Inert Doublet) that we adopt as case studies for their simplicity in illustrating the magnitude and impact of such uncertainties on the parameter space of the particle physics model itself. Our findings point toward very relevant effects of current Galactic uncertainties on the determination of particle physics parameters, and urge a systematic estimate of such uncertainties in more complex scenarios, in order to achieve constraints on the determination of new physics that realistically include all known uncertainties.

hep-ph↗