arXiv subjects

Pablo Martínez-Miravé

Publications and source records attributed to Pablo Martínez-Miravé.

At least 19 recordsLinked to original sources

arXiv2026

Unveiling Neutrino Nature with the Diffuse Supernova Background

The true nature of neutrinos--whether Dirac or Majorana--is a foundational, unresolved question. We demonstrate that the diffuse supernova neutrino background (DSNB) offers an untapped avenue to resolve this issue, provided neutrino magnetic moments are $\gtrsim 10^{-14}μ_B$. The intense magnetic fields characteristic of a subset of collapsing massive stars can trigger resonant chirality flips. This flavor conversion physics alters DSNB fluxes in measurable ways that depend on the neutrino nature. A $20$~yr combined exposure at Hyper-Kamiokande loaded with gadolinium and JUNO can unravel this signature at $90\%$ ($99\%$) confidence if the fraction of magnetorotational events exceeds $12\%$ ($20\%$) of cosmic core collapses. This result holds independent of the mass ordering and establishes the DSNB as a critical gateway to unveiling the true identity of the neutrino.

astro-ph.HE↗

arXiv2026

Diffuse Neutrino Background from Magnetorotational Stellar Core Collapses

A statistically significant detection of the diffuse supernova neutrino background (DSNB) is around the corner. To this purpose, we assess the contribution to the DSNB of magnetorotational collapses of massive stars, relying on a suite of state-of-the-art three-dimensional neutrino-magnetohydrodynamic simulations. We find that neutrinos from magnetorotational core collapses boost the high-energy tail of the DSNB spectrum, similar to what is expected from neutrino-driven black hole-forming collapses. The latest data from the Super-Kamiokande Collaboration can already exclude that more than $9\%$ of all collapsing massive stars undergo magnetorotational collapses under optimistic assumptions. A DSNB detection at $3 σ$ could take place up to $4$ yr earlier at Super-Kamiokande-Gadolinium or JUNO if the fraction of magnetorotational collapses should be larger than $10\%$. Fascinatingly, if the fraction of magnetorotational stellar collapses should be larger than $19\%$ ($13\%$), Hyper-Kamiokande could measure such a fraction at $3σ$ after ($10$ yr) $20$ yr of DSNB data taking. The combination of DSNB and electromagnetic data has the potential to resolve the degenerate contributions from magnetorotational and neutrino-driven black hole-forming collapses, providing crucial insight on the properties of the population of collapsing massive stars.

astro-ph.HE↗

arXiv2026

Detection horizon for the neutrino burst from the stellar helium flash

Low-mass stars ($M\lesssim 2\,M_\odot$) ignite helium under degenerate conditions, eventually causing a nuclear run-away -- the helium flash. The alpha-capture process on $^{14}$N produces a large amount of $^{18}$F, whose subsequent decay spawns an intense $ν_e$ burst (with average energy of $0.38$ MeV) lasting about a day. We show that, in addition, a strong $1.7$ MeV neutrino line is generated by electron capture on $^{18}$F. Detection is hindered by large backgrounds in state-of-the-art neutrino observatories, such as JUNO. In next-generation facilities, such as the Jinping neutrino experiment, the horizon for a detection with a local significance of $3 σ$ would be extended to almost $3$ pc. Although helium flashes occur a few times per year in our Galaxy, there are no stellar candidates approaching the tip of the red giant branch within $10$ pc. Hence, to date, asteroseismology remains the most promising tool for probing the most energetic thermonuclear event in the life of a low-mass star.

astro-ph.SR↗

arXiv2026

Matter- and magnetically-driven flavor conversion of neutrinos in magnetorotational collapses

The magnetorotational collapse of massive stars copiously emits neutrinos of all flavors, with a prominent hierarchy between the non-electron and electron flavor average energies. Relying on a three-dimensional neutrino-magnetohydrodynamic simulation of a $13 M_\odot$ progenitor, we investigate flavor conversion in matter. We find that, in addition to resonant flavor conversion of neutrinos and antineutrinos in matter, (anti)neutrinos experience chirality-flipping interactions due to their non-zero magnetic moment ($μ\lesssim 10^{-12} μ_B$) and large magnetic field in the source ($B \simeq 10^{15}$ G). For Majorana neutrinos, this leads to resonant flavor-changing neutrino-antineutrino mixing. The event rate expected from a Galactic collapse at current and next-generation neutrino telescopes, such as IceCube and Hyper-Kamiokande, strongly depends on the orientation of the magnetorotational collapse with respect to the observer direction and flavor conversion scenario. The event rate is expected to be larger for an observer facing head on the jet launched during the stellar collapse and peaks around $400$-$600$ ms after bounce. Our work highlights that understanding the rich phenomenology of flavor conversion in magnetorotational collapses is essential to take full advantage of the joint detection of neutrinos and gravitational waves from these sources.

astro-ph.HE↗

arXiv2026

The Highest-Energy Neutrino Event Constrains Dark Matter-Neutrino Interactions

Dark Matter-neutrino interactions affect the propagation of astrophysical neutrinos, attenuating the flux of neutrinos arriving at Earth. Using the highest-energy neutrino event detected to date by the KM3NeT collaboration as an example, and assuming an extragalactic origin, we derive limits on these interactions at $E_ν= 220^{+570}_{-110}\, \mathrm{PeV}$. Considering only the propagation on the Milky Way Dark Matter halo, we constrain the interaction cross section over the mass of the Dark Matter candidate to be, $σ_{\rm DM-ν}/m_{\rm DM} \lesssim 10^{-22}\, \mathrm{cm}^2\,\mathrm{GeV}^{-1}$. If a transient source was positively identified, the high-energy neutrino would have crossed the dark-matter halo of the source host as well, resulting in more stringent constraints (e.g., up to $ \sim$ 6 orders of magnitude assuming the blazar PKS 0605-085 is the source). These bounds on the Dark Matter-neutrino interaction cross section are translated into limits on the mass of the Dark Matter candidate, the mass of the mediator, and the coupling strength for different simplified models. We find that the constraints from the KM3-230213A high-energy event for these simplified models are almost entirely ruled out for masses above the MeV by unitarity constraints. Therefore, the attenuation of such energetic neutrinos by Dark Matter calls for richer dark sectors in order to produce meaningful constraints.

hep-ph↗

arXiv2025

Neutrinos from stars in the Milky Way

Neutrinos are produced during stellar evolution by means of thermal and thermonuclear processes. We model the cumulative neutrino flux expected at Earth from all stars in the Milky Way: the Galactic stellar neutrino flux (GS$ν$F). We account for the star formation history of our Galaxy and reconstruct the spatial distribution of Galactic stars by means of a random sampling procedure based on Gaia Data Release 2. We use the stellar evolution code $\texttt{MESA}$ to compute the neutrino emission for a suite of stellar models with solar metallicity and zero-age-main-sequence mass between $0.08M_\odot$ and $100\ M_\odot$, from their pre-main sequence phase to their final fates. We then reconstruct the evolution of the neutrino spectral energy distribution for each stellar model in our suite. The GS$ν$F lies between $\mathcal{O}(1)$ keV and $\mathcal{O}(10)$ MeV, with thermal (thermonuclear) processes responsible for shaping neutrino emission at energies smaller (larger) than $0.1$ MeV. Stars with mass larger than $\mathcal{O}(1\ M_\odot)$, located in the thin disk of the Galaxy, provide the largest contribution to the GS$ν$F. Moreover, most of the GS$ν$F originates from stars distant from Earth about $5-10$ kpc, implying that a large fraction of stellar neutrinos can reach us from the Galactic Center. Solar neutrinos and the diffuse supernova neutrino background have energies comparable to those of the GS$ν$F, challenging the detection of the latter. However, directional information of solar neutrino and GS$ν$F events, together with the annual modulation of the solar neutrino flux, could facilitate the GS$ν$F detection; this will kick off a new era for low-energy neutrino astronomy, also providing a novel probe to discover New Physics.

astro-ph.SR↗

arXiv2025

Identifying Thorne-Żytkow Objects through Neutrinos

Thorne-Żytkow Objects (TŻOs) have been predicted to form when a neutron star is engulfed by a diffuse, convective giant envelope. Accretion onto a neutron star at a rate that is larger than $10^{-4}\, M_\odot$ yr$^{-1}$ is expected to lead to significant emission of neutrinos of all flavors with energy of $1$-$100$ MeV. Since the neutrino signal is expected to largely vary in time (from milliseconds to thousands of years), we outline detection strategies tailored to the signal duration. We find that neutrino detection from TŻOs up to the Small Magellanic Cloud is within the reach of current- and next-generation neutrino observatories, such as Super- and Hyper-Kamiokande, the IceCube Neutrino Observatory, and JUNO. Interestingly, if targeted searches for neutrinos from TŻO candidates (e.g.VX Sgr in our Galaxy as well as HV 2112 and HV 11417 in the Small Magellanic Cloud) should lead to positive results, neutrinos could positively identify the nature of such sources and their accretion rate. Furthermore, the diffuse supernova neutrino background may be able to rule out extreme scenarios for the formation and accretion rates of TŻOs. Our findings should serve as motivation for establishing dedicated searches for neutrino emission from TŻOs. This is especially timely since it is challenging to detect TŻOs via electromagnetic radiation unambiguously, and the TŻO gravitational wave signal could be probed with next-generation detectors for sources within our Galaxy only.

astro-ph.HE↗

arXiv2024

The Unknowns of the Diffuse Supernova Neutrino Background Hinder New Physics Searches

Neutrinos traveling over cosmic distances are ideal probes of new physics. We leverage on the approaching detection of the diffuse supernova neutrino background (DSNB) to explore whether, if the DSNB showed departures from theoretical predictions, we could attribute such modifications to new physics unequivocally. In order to do so, we focus on visible neutrino decay. Many of the signatures from neutrino decay are degenerate with astrophysical unknowns entering the DSNB modeling. Next generation neutrino observatories, such as Hyper-Kamiokande, JUNO, as well as DUNE, will set stringent limits on a neutrino lifetime over mass ratio $τ/m \sim 10^{9}$-$10^{10}$ s eV$^{-1}$ at $90\%$ C.L., if astrophysical uncertainties and detector backgrounds were to be fully under control. However, if the lightest neutrino is almost massless and the neutrino mass ordering is normal, constraining visible decay will not be realistically possible in the coming few decades. We also assess the challenges of distinguishing among different new physics scenarios (such as visible decay, invisible decay, and quasi-Dirac neutrinos), all leading up to similar signatures in the DSNB. This work shows that the DSNB potential for probing new physics strongly depends on an improved understanding of the experimental backgrounds at next generation neutrino observatories as well as progress in the DSNB modeling.

astro-ph.HE↗

arXiv2024

The next galactic supernova can uncover mass and couplings of particles decaying to neutrinos

Many particles predicted by extensions of the Standard Model feature interactions with neutrinos, e.g., Majoron-like bosons $ϕ$. If the mass of $ϕ$ is larger than about 10 keV, they can be produced abundantly in the core of the next galactic core-collapse supernova through neutrino coalescence, and leave it with energies of around 100 MeV. Their subsequent decay to high-energy neutrinos and anti-neutrinos provides a distinctive signature at Earth. Ongoing and planned neutrino and dark matter experiments allow us to reconstruct the energy, flavor, and time of arrival of these high-energy neutrinos. For the first time, we show that these measurements can help pinpointing the mass of $ϕ$ and its couplings to neutrinos of different flavor. Our results can be generalized in a straightforward manner to other hypothetical feebly interacting particles, like novel gauge bosons or heavy neutral leptons, that decay into neutrinos.

hep-ph↗

arXiv2024

Effects of Neutrino-Ultralight Dark Matter Interaction on the Cosmic Neutrino Background

Ultralight dark matter interacting with sterile neutrinos would modify the evolution and properties of the cosmic neutrino background through active-sterile neutrino mixing. We investigate how such an interaction would induce a redshift dependence in neutrino masses. We highlight that cosmological constraints on the sum of neutrino masses would require reinterpretation due to the effective mass generated by neutrino-dark matter interactions. Furthermore, we present an example where such interactions can alter the mass ordering of neutrinos in the early Universe, compared to what we expect today. We also address the expected changes in the event rates in a PTOLEMY-like experiment, which aims to detect the cosmic neutrino background via neutrino capture, and discuss projected constraints.

hep-ph↗

arXiv2024

The Sun and core-collapse supernovae are leading probes of the neutrino lifetime

The large distances travelled by neutrinos emitted from the Sun and core-collapse supernovae together with the characteristic energy of such neutrinos provide ideal conditions to probe their lifetime, when the decay products evade detection. We investigate the prospects of probing invisible neutrino decay capitalising on the detection of solar and supernova neutrinos as well as the diffuse supernova neutrino background (DSNB) in the next-generation neutrino observatories Hyper-Kamiokande, DUNE, JUNO, DARWIN, and RES-NOVA. We find that future solar neutrino data will be sensitive to values of the lifetime-to-mass ratio $τ_1/m_1$ and $τ_2/m_2$ of $\mathcal{O}(10^{-1} - 10^{-2})$ s/eV. From a core-collapse supernova explosion at $10$ kpc, lifetime-to-mass ratios of the three mass eigenstates of $\mathcal{O}(10^5)$ s/eV could be tested. After $20$ years of data taking, the DSNB would extend the sensitivity reach of $τ_1/m_1$ to $10^{8}$ s/eV. These results promise an improvement of about $6 -15$ orders of magnitude on the values of the decay parameters with respect to existing limits.

astro-ph.HE↗

arXiv2023

Synergy between cosmological and laboratory searches in neutrino physics

The intersection of the cosmic and neutrino frontiers is a rich field where much discovery space still remains. Neutrinos play a pivotal role in the hot big bang cosmology, influencing the dynamics of the universe over numerous decades in cosmological history. Recent studies have made tremendous progress in understanding some properties of cosmological neutrinos, primarily their energy density. Upcoming cosmological probes will measure the energy density of relativistic particles with higher precision, but could also start probing other properties of the neutrino spectra. When convolved with results from terrestrial experiments, cosmology can become even more acute at probing new physics related to neutrinos or even Beyond the Standard Model (BSM). Any discordance between laboratory and cosmological data sets may reveal new BSM physics and/or suggest alternative models of cosmology. We give examples of the intersection between terrestrial and cosmological probes in the neutrino sector, and briefly discuss the possibilities of what different laboratory experiments may see in conjunction with cosmological observatories.

hep-ph↗

arXiv2023

Neutrino properties from the laboratory and the cosmos

Neutrinos are amongst the most abundant particles in the universe. The fact that they are massive particles proves that the Standard Model is an incomplete theory and needs to be extended. This thesis focuses on the study of neutrino properties from the available data from laboratory experiments and cosmological observations. It also presents sensitivity studies for future neutrino experiments. The first part covers the status of the determination of the oscillation parameters in the three-neutrino framework, the mass ordering and the absolute mass scale. A second part is devoted to other neutrino properties predicted in neutrino mass models. The topics covered include the study of spin-flavour precession in solar neutrinos from non-zero neutrino magnetic moments, the prospects for neutrino non-standard interactions with quarks from the solar sector and the expected limits on CPT violation from a separate analysis of neutrino and antineutrino data. Regarding cosmology, the impact of non-standard interactions with electrons and a non-unitary three-neutrino mixing matrix in the process of neutrino decoupling are addressed. Finally, a third part explores possible connections between dark matter and neutrinos. The existence of dark matter has been proven indirectly via its gravitational effects. This thesis presents two studies that explore how neutrinos could probe the fraction of dark matter that could exist in the form of primordial black holes and the experimental signatures expected from a hypothetical coupling between neutrinos and an ultralight scalar dark matter candidate.

hep-ph↗

arXiv2023

Neutrino CPT violation in the solar sector

In this paper we place new bounds on CPT violation in the solar neutrino sector analyzing the results from solar experiments and KamLAND. We also discuss the sensitivity of the next-generation experiments DUNE and Hyper-Kamiokande, which will provide accurate measurements of the solar neutrino oscillation parameters. The joint analysis of both experiments will further improve the precision due to cancellations in the systematic uncertainties regarding the solar neutrino flux. In combination with the next-generation reactor experiment JUNO, the bound on CPT violation in the solar sector could be improved by one order of magnitude in comparison with current constraints. The distinguishability among CPT-violating neutrino oscillations and neutrino non-standard interactions in the solar sector is also addressed.

hep-ph↗

arXiv2023

Cosmology-friendly time-varying neutrino masses via the sterile neutrino portal

We investigate a consistent scenario of time-varying neutrino masses, and discuss its impact on cosmology, beta decay, and neutrino oscillation experiments. Such time-varying masses are assumed to be generated by the coupling between a sterile neutrino and an ultralight scalar field, which in turn affects the light neutrinos by mixing. Besides, the scalar could act as an ultralight dark matter candidate. We demonstrate how various cosmological bounds, such as those coming from Big Bang nucleosynthesis, the cosmic microwave background, as well as large scale structures, can be evaded in this model. This scenario can be further constrained using multiple terrestrial experiments. In particular, for beta-decay experiments like KATRIN, non-trivial distortions to the electron spectrum can be induced, even when time-variation is fast and gets averaged out. Furthermore, the presence of time-varying masses of sterile neutrinos will alter the interpretation of light sterile neutrino parameter space in the context of the reactor and gallium anomalies. In addition, we also study the impact of such time-varying neutrino masses on results from the BEST collaboration, which have recently strengthened the gallium anomaly. If confirmed, we find that the time-varying neutrino mass hypothesis could give a better fit to the recent BEST data.

hep-ph↗

arXiv2022

Non-unitary three-neutrino mixing in the early Universe

Deviations from unitarity in the three-neutrino mixing canonical picture are expected in many physics scenarios beyond the Standard Model. The mixing of new heavy neutral leptons with the three light neutrinos would in principle modify the strength and flavour structure of charged-current and neutral-current interactions with matter. Non-unitarity effects would therefore have an impact on the neutrino decoupling processes in the early Universe and on the value of the effective number of neutrinos, $N_{\rm eff}$. We calculate the cosmological energy density in the form of radiation with a non-unitary neutrino mixing matrix, addressing the possible interplay between parameters. Highly accurate measurements of $N_{\rm eff}$ from forthcoming cosmological observations can provide independent and complementary limits on the departures from unitarity. For completeness, we relate the scenario of small deviations from unitarity to non-standard neutrino interactions and compare the forecasted constraints to other existing limits in the literature.

hep-ph↗

arXiv2022

Solar $\barν_e$ flux: Revisiting bounds on neutrino magnetic moments and solar magnetic field

The interaction of neutrino transition magnetic dipole moments with magnetic fields can give rise to the phenomenon of neutrino spin-flavour precession (SFP). For Majorana neutrinos, the combined action of SFP of solar neutrinos and flavour oscillations would manifest itself as a small, yet potentially detectable, flux of electron antineutrinos coming from the Sun. Non-observation of such a flux constrains the product of the neutrino magnetic moment $μ$ and the strength of the solar magnetic field $B$. We derive a simple analytical expression for the expected $\barν_e$ appearance probability in the three-flavour framework and we use it to revisit the existing experimental bounds on $μB$. A full numerical calculation has also been performed to check the validity of the analytical result. We also present our numerical results in energy-binned form, convenient for analyses of the data of the current and future experiments searching for the solar $\barν_e$ flux. In addition, we give a comprehensive compilation of other existing limits on neutrino magnetic moments and of the expressions for the probed effective magnetic moments in terms of the fundamental neutrino magnetic moments and leptonic mixing parameters.

hep-ph↗

arXiv2021

Cosmological radiation density with non-standard neutrino-electron interactions

Non-standard interactions (NSI) between neutrinos and electrons can significantly modify the decoupling of neutrinos from the plasma. These interactions have two effects on the overall picture: (i) they alter neutrino oscillations though matter effects and (ii) they modify the scattering and annihilation processes involving neutrinos and electrons and positrons. We study the role of non-universal and flavour-changing NSI in the decoupling and how they impact the determination of the effective number of neutrinos, $N_{eff}$. We examine the degeneracies between NSI parameters and we compare the expected sensitivity from future cosmological surveys with the current limits from terrestrial experiments. We outline the complementarity between both approaches.

hep-ph↗