arXiv subjects

Pedro De la Torre Luque

Publications and source records attributed to Pedro De la Torre Luque.

31 records · Page 2Linked to original sources

arXiv2025

Anomalous Ionization in the Central Molecular Zone by sub-GeV Dark Matter

We demonstrate that the anomalous ionization rate observed in the Central Molecular Zone can be attributed to MeV dark matter annihilations into $e^+e^-$ pairs for galactic dark matter profiles with slopes $γ>1$. The low annihilation cross-sections required avoid cosmological constraints and imply no detectable inverse Compton, bremsstrahlung or synchrotron emissions in radio, X and gamma rays. The possible connection to the source of the unexplained 511 keV line emission in the Galactic Center suggests that both observations could be correlated and have a common origin.

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arXiv2024

Multimessenger constraints for electrophilic feebly interacting particles from supernovae

Several extensions of the Standard Model predict the existence of sub-GeV particles that can be copiously produced in the cores of supernovae. A broad family of these particles are dubbed feebly interacting particles (FIPs), which can have masses of up to a few hundreds of MeV. Here, we review the most recent and leading constraints on electrophilic FIPs, describing multimessenger techniques that allow us to probe the full phenomenology of the electron/positron emission produced by these FIPs; from their associated X-ray emission to the production of the $511$~keV line. Furthermore, the approach described here is independent of the specific particle model and can be translated to the coupling and other properties of a variety of different particles, such as axion-like particles, sterile neutrinos or dark photons

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arXiv2024

Multimessenger search for electrophilic feebly interacting particles from supernovae

We study MeV-scale electrophilic Feebly Interacting Particles (FIPs), that may be abundantly produced in Supernova (SN) explosions, escape the star and decay into electrons and positrons. This exotic injection of leptons in the Milky Way leaves an imprint in both photon and cosmic-ray fluxes. Specifically, positrons lose energy and annihilate almost at rest with background electrons, producing photons with $511$ keV energy. In addition, electrons and positrons radiate photons through bremsstrahlung emission and upscatter the low-energy galactic photon fields via the inverse Compton process generating a broad emission from X-ray to $γ$-ray energies. Finally, electrons and positrons are directly observable in cosmic ray experiments. In order to describe the FIP-induced lepton injection in full generality, we use a model independent parametrization which can be applied to a host of FIPs such as axion-like particles, dark photons and sterile neutrinos. Theoretical predictions are compared to experimental data to robustly constrain FIP-electron interactions with an innovative multimessenger analysis.

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arXiv2024

Robust constraints on feebly interacting particles using XMM-Newton

During galactic Supernova (SN) explosions, a large amount of feebly interacting particles (FIPs) may be produced. In this work we analyze electrophilic FIPs with masses in the MeV-range that escape from SN and decay into electron-positron pairs, causing an exotic leptonic injection. This contribution adds up to known components, leading to an unexpected excess of X-ray fluxes generated by inverse-Compton scattering of the injected particles on low-energy photon backgrounds. For the first time in the context of FIPs, we use XMM-Newton X-ray measurements to obtain the strongest and most robust bounds on electrophilic FIPs produced by SN in our Galaxy.

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arXiv2024

$γ$ rays from in-flight positron annihilation as a probe of new physics

The $γ$ ray emission originating from in-flight annihilation (IA) of positrons is a powerful observable for constraining high-energy positron production from exotic sources. By comparing diffuse $γ$ ray observations of INTEGRAL, COMPTEL and EGRET to theoretical predictions, we set the most stringent constraints on electrophilic feebly interacting particles (FIPs), thereby proving IA as a valuable probe of new physics. In particular, we extensively discuss the case of MeV-scale sterile neutrinos, where IA sets the most stringent constraints, excluding $|U_{\mu4}|^{2} \gtrsim 10^{-13}$ and $|U_{\tau4}|^{2} \gtrsim 2\times 10^{-13}$ for sterile neutrinos mixed with $μ$ and $τ$ neutrinos respectively. These constraints improve existing limits by more than an order of magnitude. We briefly discuss the application of these results to a host of exotic positron sources such as dark photons, axion-like particles, primordial black holes (PBHs) and sub-GeV dark matter (DM).

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arXiv2024

Importance of cosmic ray propagation on sub-GeV dark matter constraints

We study sub-GeV dark matter (DM) particles that may annihilate or decay into SM particles producing an exotic injection component in the Milky Way that leaves an imprint in both photon and cosmic ray (CR) fluxes. Specifically, the DM particles may annihilate or decay into $e^+e^-$, $μ^+μ^-$ or $π^+π^-$ and may radiate photons through their $e^\pm$ products. The resulting $e^\pm$ products can be directly observed in probes such as {\sc Voyager 1}. Alternatively, the $e^\pm$ products may produce bremsstrahlung radiation and upscatter the low-energy galactic photon fields via the inverse Compton process generating a broad emission from $X$-ray to $γ$-ray energies observable in experiments such as {\sc Xmm-Newton}. We find that we get a significant improvement in the DM annihilation and decay constraints from {\sc Xmm-Newton} (excluding thermally averaged cross sections of $10^{-31}$ cm$^3$ s$^{-1} \lesssim \langle σv\rangle \lesssim10^{-26}$ cm$^3$ s$^{-1}$ and decay lifetimes of $10^{26} \textrm{s}\lesssim τ\lesssim 10^{28} \textrm{s}$ respectively) by including best fit CR propagation and diffusion parameters. This yields the strongest astrophysical constraints for this mass range of DM of 1 MeV to a few GeV and even surpasses cosmological bounds across a wide range of masses as well.

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arXiv2024

Antiproton Bounds on Dark Matter Annihilation from a Combined Analysis Using the DRAGON2 Code

Early studies of the AMS-02 antiproton ratio identified a possible excess over the expected astrophysical background that could be fit by the annihilation of a weakly interacting massive particle (WIMP). However, recent efforts have shown that uncertainties in cosmic-ray propagation, the antiproton production cross-section, and correlated systematic uncertainties in the AMS-02 data, may combine to decrease or eliminate the significance of this feature. We produce an advanced analysis using the DRAGON2 code which, for the first time, simultaneously fits the antiproton ratio along with multiple secondary cosmic-ray flux measurements to constrain astrophysical and nuclear uncertainties. Compared to previous work, our analysis benefits from a combination of: (1) recently released AMS-02 antiproton data, (2) updated nuclear fragmentation cross-section fits, (3) a rigorous Bayesian parameter space scan that constrains cosmic-ray propagation parameters. We find no statistically significant preference for a dark matter signal and set strong constraints on WIMP annihilation to $b\bar{b}$, ruling out annihilation at the thermal cross-section for dark matter masses below $\sim200$~GeV. We do find a positive residual that is consistent with previous work, and can be explained by a $\sim70$~GeV WIMP annihilating below the thermal cross-section. However, our default analysis finds this excess to have a local significance of only 2.8$σ$, which is decreased to 1.8$σ$ when the look-elsewhere effect is taken into account.

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arXiv2023

The FLUKA cross sections for cosmic-ray leptons and uncertainties on current positron predictions

Cosmic-ray (CR) antiparticles have the potential to reveal signatures of unexpected astrophysical processes and even new physics beyond the Standard Model. Recent CR detectors have provided accurate measurements of the positron flux, revealing the so-called positron excess at high energies. However, the uncertainties related to the modelling of the local positron flux are still very high, significantly affecting our models of positron emission from pulsars and current dark matter searches. In this work, we report a new set of cross sections for positron and electron production derived from the {\tt FLUKA} code. We compare them with the most extended cross-section data-sets and show the impact of neglecting the positron production from heavy CRs. Then, we review the most significant sources of uncertainties in our current estimations of the secondary positron flux at Earth and examine for the first time the impact of considering the spiral arm structure of the Galaxy in these estimations. Finally, we provide state-of-the-art predictions of the local positron flux and discuss the limitations of our dark matter searches with positrons and difficulties to determine the contribution from pulsars to the positron flux at low energies.

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arXiv2023

Detecting neutrino-boosted axion dark matter in the MeV gap

The elusive nature of Dark Matter (DM) remains a mystery far from being solved. A vast effort is dedicated to search for signatures of feeble DM interactions with Standard Model particles. In this work, we explore the signatures of axion DM boosted by interactions with Supernova neutrinos: Neutrino-Boosted Axion DM ($ν$BADM). We focus on $ν$BADM converting into photons in the Galactic magnetic field, generating a peculiar gamma-ray flux. This signal falls in the poorly explored MeV energy range, that will be probed by next generation gamma-ray missions. Once more, astrophysical searches might act as a probe of fundamental physics, unveiling the nature and properties of DM.

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arXiv2022

Prospects for detection of a Galactic diffuse neutrino flux

A Galactic cosmic-ray transport model featuring non-homogeneous transport has been developed over the latest years. This setup is aimed at reproducing gamma-ray observations in different regions of the Galaxy (with particular focus on the progressive hardening of the hadronic spectrum in the inner Galaxy) and was shown to be compatible with the very-high-energy gamma-ray diffuse emission recently detected up to PeV energies. In this work, we extend the results previously presented to test the reliability of that model throughout the whole sky. To this aim, we compare our predictions with detailed longitude and latitude profiles of the diffuse gamma-ray emission measured by Fermi-LAT for different energies and compute the expected Galactic neutrino diffuse emission, comparing it with current limits from the ANTARES collaboration. We emphasize that the possible detection of a Galactic neutrino component will allow us to break the degeneracy between our model and other scenarios featuring prominent contributions from unresolved sources and TeV halos.

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arXiv2022

Optimized FLUKA cross sections for cosmic-ray propagation studies

The current great precision on cosmic-ray (CR) spectral data allows us to precisely test our simple models on propagation of charged particles in the Galaxy. However, our studies are severely limited by the uncertainties related to cross sections for CR interactions. Therefore we have developed a new set of cross sections derived from the FLUKA Monte Carlo code, which is optimized for the treatment of CR interactions. We show these cross sections and the main results on their application for CR propagation studies. Finally, we discuss the prediction of a low-energy break in the electrons spectra inferred from gamma-ray data.

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arXiv2022

Galactic diffuse gamma rays meet the PeV frontier

The Tibet AS$γ$ and LHAASO collaborations recently reported the observation of a $γ$-ray diffuse emission with energy up to the PeV from the Galactic plane. We discuss the relevance of non-uniform cosmic-ray transport scenarios and the implications of these results for cosmic-ray physics. We use the {\tt DRAGON} and {\tt HERMES} codes to build high-resolution maps and spectral distributions of that emission for several representative models under the condition that they reproduce a wide set of local cosmic-ray data up to 100 PeV. We show that the energy spectra measured by Tibet AS$γ$, LHAASO, ARGO-YBJ and Fermi-LAT in several regions of interest in the sky can all be consistently described in terms of the emission arising by the Galactic cosmic-ray "sea". We also show that all our models are compatible with IceTop $γ$-ray upper limits. Our results favor transport models characterized by spatial-dependent diffusion although some degeneracy remains between the choice of the transport scenario and that of the cosmic-ray spectral shape above 10 TeV. We discuss the role of forthcoming measurements in resolving that ambiguity.

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arXiv2021

The theory of cosmic-ray scattering on pre-existing MHD modes meets data

We present a comprehensive study about the phenomenological implications of the theory describing Galactic cosmic-ray scattering onto magnetosonic and Alfvénic fluctuations in the $\mathrm{GeV} - \mathrm{PeV}$ domain. We compute a set of diffusion coefficients from first principles, for different values of the Alfvénic Mach number and other relevant parameters associated to both the Galactic halo and the extended disk, taking into account the different damping mechanisms of turbulent fluctuations acting in these environments. We confirm that the scattering rate associated to Alfvénic turbulence is highly suppressed if the anisotropy of the cascade is taken into account. On the other hand, we highlight that magnetosonic modes play a dominant role in Galactic confinement of cosmic rays up to $\mathrm{PeV}$ energies. We implement the diffusion coefficients in the numerical framework of the {\tt DRAGON} code, and simulate the equilibrium spectrum of different primary and secondary cosmic-ray species. We show that, for reasonable choices of the parameters under consideration, all primary and secondary fluxes at high energy (above a rigidity of $\simeq 200 \, \mathrm{GV}$) are correctly reproduced within our framework, in both normalization and slope.

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