arXiv subjects

Antonio Ambrosone

Publications and source records attributed to Antonio Ambrosone.

12 recordsLinked to original sources

arXiv2026

Exploring memory-burdened primordial black holes with ultra-high-energy cosmic-rays

Quantum backreaction effects may quench Hawking evaporation through a ``memory burden'', allowing primordial black holes (PBHs) with formation masses well below $10^{15}~\mathrm{g}$ to survive to the present and contribute to the dark matter. We show that ultra-high-energy cosmic rays (UHECRs) provide a powerful and previously unexplored probe of this scenario. We compute the proton and neutron emission from memory-burdened PBHs, including the Galactic-halo contribution and the extragalactic proton component, and confront it with the Pierre Auger Observatory proton spectrum and its EeV neutron limits from the Galactic plane. This yields new constraints on the PBH dark-matter fraction as a function of the PBH formation mass and the evaporation-suppression parameter $k$. For $k\gtrsim 3$ the non-observation of ultra-high-energy protons leads to bounds competitive with those from UHE gamma rays, while neutron limits remain comparable to high-energy neutrino constraints. Our results highlights the key role of multi-messenger astronomy in constraining beyond-the-standard-model scenarios.

astro-ph.HE↗

arXiv2026

Constraining Super-Heavy Dark Matter with the KM3-230213A Neutrino Event

Recently, the KM3NeT collaboration detected an astrophysical neutrino event, KM3-230213A, with an energy of approximately $220~\rm PeV$, providing unprecedented insights into the ultra-high-energy Universe. In this study, we introduce a novel likelihood framework designed to leverage this event to constrain the properties of super-heavy dark matter (SHDM) decay. Our approach systematically integrates multi-messenger constraints from galactic and extragalactic neutrino flux measurements by IceCube, the absence of comparable neutrino events at IceCube and Auger observatories, and the latest gamma-ray experiment upper limits. Our findings impose the most stringent constraints to date, placing a lower bound on the SHDM lifetime at $\gtrsim 5\cdot 10^{29}-10^{30} \rm s$. Importantly, we identify, for the first time, the significant potential of galactic neutrino flux measurements in advancing dark matter research. Future investigations targeting astrophysical neutrinos originating from the Galactic Center at energies above $10~\rm PeV$ will be crucial, not only for understanding the origin of the cosmic-ray knee but also for exploring the possible contributions of super-heavy dark matter to our Universe.

astro-ph.HE↗

arXiv2025

Scrutinizing the cosmogenic origin of the KM3-230213A event: A Multimessenger Perspective

The recent detection of the neutrino event KM3-230213A ($\sim$~220 PeV) by the KM3NeT/ARCA telescope, the most energetic ever observed, could represent the long-awaited evidence for a cosmogenic origin, arising from the interaction of an ultra-high-energy cosmic ray with background photons. Its secure confirmation would mark a major advance in high-energy astrophysics. We perform a self-consistent multimessenger transport calculation of protons and their secondary $γ$-rays and neutrinos from cosmologically evolving sources, confronting predictions with data from the Pierre Auger Observatory, IceCube, KM3NeT, and the Fermi-LAT isotropic $γ$-ray background. A steep sub-ankle proton component saturates the diffuse $γ$-ray background and is disfavoured, whereas a hard proton spectrum extending beyond $10^{20}$~eV with evolution $\propto (1+z)^3$ reproduces KM3-230213A without violating any limits. This scenario requires a proton fraction $\lesssim 10$\% at $3\times 10^{19}$~eV and excludes faster-evolving sources. Joint UHE-neutrino and $γ$-ray observations thus sharpen constraints on extragalactic cosmic-ray sources and set targets for AugerPrime and next-generation neutrino telescopes.

astro-ph.HE↗

arXiv2025

The Origin of the Very-High-Energy Diffuse $γ$-Ray Emission: The Case for Galactic Source Cocoons

The secondary/primary cosmic-ray ratios and the diffuse backgrounds of gamma rays and neutrinos provide us with complementary information about the transport of Galactic cosmic rays~(CRs). We used the recent measurement of the diffuse gamma ray background in the $\sim \rm TeV -\rm PeV$ range by LHAASO and of the very high-energy diffuse neutrino background from the Galactic disc by IceCube to show that CRs may be accumulating an approximately energy independent grammage $X\sim 0.4\, \rm g \, \rm cm^{-2}$, in regions where gamma rays and neutrinos are produced with a hard spectrum, resembling the source spectrum. We speculate that this grammage reflects the early stages of cosmic ray transport around sources, in what are referred to as cocoons, where particles spend $\sim 0.3\, \rm Myr$ before starting their journey in the Galactic environment.

astro-ph.HE↗

arXiv2024

Constraining the hadronic properties of star-forming galaxies above $1\, \rm GeV$ with 15-years Fermi-LAT data

Star-forming and starburst galaxies (SFGs and SBGs) are powerful emitters of non-thermal $γ$-rays and neutrinos, due to their intense phases of star-formation activity, which should confine high-energy Cosmic-Rays (CRs) inside their environments. In this paper, using the publicly-available \texttt{fermitools}, we analyse 15.3 years of $γ$-ray between $1-1000\, \rm GeV$ data for 70 sources, 56 of which were not previously detected. We find at~$4σ$ level an indication of $γ$-ray emission for other two SBGs, namely M 83 and NGC 1365. By contrast, we find that, even with the new description of background, the significance for the $γ$-ray emission of M 33~(initially reported as discovered) still stands at $\sim \, 4σ$ (as already reported by previous works). Along with previous findings, the flux of each detected source is consistent with a $\sim E^{-2.3/2.4}$ spectrum, compatible with the injected CR flux inferred for CRs in the Milky-Way. We notice that the correlation between the calorimetric fraction~$F_{\rm cal}$ of high-energy protons in SFGs and SBGs (the fraction of high-energy protons actually producing high-energy $γ$-rays and neutrinos) and the SFR is in accordance with the expected scaling relation for CR escape dominated by advection. We remark that undiscovered sources strongly constrain $F_{\rm cal}$ at 95\% CL, providing fundamental information when we interpret the results as common properties of SFGs and SBGs. Finally, we find that these sources might contribute $(12\pm 3)\%$ to the EGB, while the corresponding diffuse neutrino flux strongly depends on the spectral index distribution along the source class.

astro-ph.HE↗

arXiv2024

Berezinsky Hidden Sources: An Emergent Tension in the High-Energy Neutrino Sky?

The IceCube Collaboration has recently reported compelling evidence of high-energy neutrino emission from NGC~1068, and also mild excesses for NGC 4151 and CGCG420-015, local Seyfert galaxies. This has increased the interest along neutrino emission from hot-corona surrounding the super massive black holes of Seyfert Galaxies. In this paper, we revisit phenomenological constraints on the neutrino emission from hot-coronae of seyfert galaxies, using an assumption of equi-ripartition between cosmic-rays and magnetic energy densities. We show that not only these sources are consistent with such an assumption but also that the data point towards low beta plasma parameters inside Seyfert Galaxies. We exploit this finding to constrain the Seyfert diffuse neutrino flux and we obtain that, in order not to overproduce neutrinos, not all the sources can be in an equi-ripartition state. We conclude (along with previous findings) that seyfert galaxies cannot explain the diffuse neutrino spectrum above $\sim 100\, \rm TeV$, allowing space for other astrophysical sources.

astro-ph.HE↗

arXiv2024

Galactic Diffuse Neutrino Emission from Sources beyond the Discovery Horizon

The IceCube Neutrino Observatory has recently reported strong evidence for neutrino emission from the Galactic plane. The signal is consistent with model predictions of diffuse emission from cosmic ray propagation in the interstellar medium. However, due to IceCube's limited potential of identifying individual neutrino sources, it is also feasible that unresolved Galactic sources could contribute to the signal. We investigate the contribution of this quasi-diffuse emission and show that the observed Galactic diffuse flux at 100 TeV could be dominated by hard emission of unresolved sources. Particularly interesting candidate sources are young massive stellar clusters that have been considered as cosmic-ray PeVatrons. We examine whether this hypothesis can be tested by the upcoming KM3NeT detector or the planned future facility IceCube-Gen2 with about five times the sensitivity of IceCube.

astro-ph.HE↗

arXiv2023

Starburst Nuclei as Light Dark Matter Laboratories

Starburst galaxies are well-motivated astrophysical emitters of high-energy gamma-rays. They are well-known cosmic-ray "reservoirs", thanks to their large magnetic fields which confine high-energy protons for $\sim 10^5$ years. Over such long times, cosmic-ray transport can be significantly affected by scatterings with sub-GeV dark matter. Here we point out that this scattering distorts the cosmic-ray spectrum, and the distortion can be indirectly observed by measuring the gamma-rays produced by cosmic-rays via hadronic collisions. Present gamma-ray data show no sign of such a distortion, leading to stringent bounds on the cross section between protons and dark matter. These are highly complementary with current bounds and have large room for improvement with the future gamma-ray measurements in the 0.1-10 TeV range from the Cherenkov Telescope Array, which can strengthen the limits by as much as two orders of magnitude.

astro-ph.HE↗

arXiv2022

Towards baryogenesis via absorption from Primordial Black Holes

Recently Dolgov and Pozdnyakov proposed a new baryogenesis mechanism in which baryon asymmetry is produced without violating baryon number at the Lagrangian level. In this scenario, baryon asymmetry is generated by absorption of a new particle X carrying baryon number onto Primordial Black Holes (PBHs). Assuming CP-violation, the particle X is absorbed at a different rate than the antiparticle $\bar{X}$, producing an asymmetry in the baryonic number. We independently test this scenario, finding that it suffers from two fundamental issues.\\ At the phenomenological level, strong absorption by PBHs initially increases the baryon asymmetry. However, at later times such asymmetry is completely absorbed by PBHs. In order to overcome this issue, we account for PBH evaporation, which provides a natural way of halting the absorption while keeping a finite baryon asymmetry. We provide a systematic study of the parameter space, identifying the regions leading to the production of the baryon asymmetry without violating the known constraints on PBHs concentration. At the theoretical level, a model realizing the CP-violation postulated in this scenario is difficult to realize. We show, by implementing a minimal model, that the framework proposed in the original work in order to produce CP-violation, even if qualitatively correct, is quantitatively in disagreement with the observed baryon asymmetry, namely this mechanism produces only a fraction of the total baryon asymmetry.

hep-ph↗

arXiv2021

Could nearby star-forming galaxies light up the point-like neutrino sky?

Star-forming and starburst galaxies, which are well-known cosmic-rays reservoirs, are expected to emit gamma-rays and neutrinos predominantly via hadronic collisions. In this Letter, we analyze the 10-year Fermi-LAT spectral energy distributions of 13 nearby galaxies by means of a physical model which accounts for high-energy proton transport in starburst nuclei and includes the contribution of primary and secondary electrons. In particular, we test the hypothesis that the observed gamma-ray fluxes are mostly due to star-forming activity, in agreement with the available star formation rates coming from IR and UV observations. Through this observation-based approach, we determine the most-likely neutrino counterpart from star-forming and starburst galaxies and quantitatively assess the ability of current and upcoming neutrino telescopes to detect them as point-like sources. Remarkably, we find that the cores of the Small Magellanic Cloud and the Circinus galaxy are potentially observable by KM3NeT/ARCA with 6 years of observation. Moreover, most of the nearby galaxies are likely to be just a factor of a few below the KM3NeT and IceCube-Gen2 point-like sensitivities. After investigating the prospects for detection of gamma-rays above TeV energies from these sources, we conclude that the joint observations of high-energy neutrinos and gamma-rays with upcoming telescopes will be an objective test for our emission model and may provide compelling evidence of star-forming activity as a tracer of neutrino production.

astro-ph.HE↗

arXiv2021

KM3NeT/ARCA expectations in view of a novel multimessenger study of starburst galaxies

Starburst galaxies (SBGs) and more in general starforming galaxies represent a class of galaxies with a high star formation rate (up to 100 solar masses/year). Despite their low luminosity, they can 19 be considered as guaranteed "factories" of high energy neutrinos, being "reservoirs" of accelerated 20 cosmic rays and hosting a high density target gas in the central region. In this contribution 21 we present a novel multimessenger study of these sources and the possibility of observing their 22 neutrino signals with the KM3NeT/ARCA telescope. The differential sensitivity for different SBG 23 scenarios is reported considering track-like neutrino events in the 100 GeV-100 PeV energy range.

astro-ph.HE↗

arXiv2021

Starburst galaxies strike back: a multi-messenger analysis with Fermi-LAT and IceCube data

Starburst galaxies, which are known as "reservoirs" of high-energy cosmic-rays, can represent an important high-energy neutrino "factory" contributing to the diffuse neutrino flux observed by IceCube. In this paper, we revisit the constraints affecting the neutrino and gamma-ray hadronuclear emissions from this class of astrophysical objects. In particular, we go beyond the standard prototype-based approach leading to a simple power-law neutrino flux, and investigate a more realistic model based on a data-driven blending of spectral indexes, thereby capturing the observed changes in the properties of individual emitters. We then perform a multi-messenger analysis considering the extragalactic gamma-ray background (EGB) measured by Fermi-LAT and different IceCube data samples: the 7.5-year High-Energy Starting Events (HESE) and the 6-year high-energy cascade data. Along with starburst galaxies, we take into account the contributions from blazars and radio galaxies as well as the secondary gamma-rays from electromagnetic cascades. Remarkably, we find that, differently from the highly-constrained prototype scenario, the spectral index blending allows starburst galaxies to account for up to $40\%$ of the HESE events at $95.4\%$ CL, while satisfying the limit on the non-blazar EGB component. Moreover, values of $\mathcal{O}(100~\mathrm{PeV})$ for the maximal energy of accelerated cosmic-rays by supernovae remnants inside the starburst are disfavoured in our scenario. In broad terms, our analysis points out that a better modeling of astrophysical sources could alleviate the tension between neutrino and gamma-ray data interpretation.

astro-ph.HE↗