arXiv subjects

Pedro De la Torre Luque

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

At least 19 recordsLinked to original sources

arXiv2026

Constraining dark matter using 20-year INTEGRAL/IBIS observations II: Sub-GeV dark matter

We present new constraints on sub-GeV dark matter (DM) annihilation and decay using twenty years of diffuse hard X-ray observations from the INTEGRAL/IBIS telescope. By performing a joint analysis of the spectral and morphological information contained in the IBIS dataset, we simultaneously fit Galactic longitudinal profiles and energy spectra, exploiting their complementary signatures to disentangle potential DM signals from the dominant astrophysical backgrounds. We use physically motivated background models combining inverse-Compton (IC) emission from Galactic cosmic-ray electrons with thermal emission from unresolved accreting white dwarfs, and consistently include the secondary IC emission generated by DM-induced electron and positron populations propagated through the Galaxy. We conservatively derive 95% upper limits on the annihilation cross section $\langleσv\rangle$ and decay half-life $τ$ for the $e^+e^-$, $μ^+μ^-$, and $π^+π^-$ final states across the mass range 1 MeV to 5 GeV. Our constraints are in the range $10^{-28}$ cm$^3$/s $\lesssim \langleσv\rangle \lesssim 10^{-26}$ cm$^3$/s for annihilation and $τ\gtrsim 10^{25}$ s for decay at DM masses of a few MeV, improving upon existing X-ray limits by up to two orders of magnitude over much of the mass range. Our bounds are translated into constraints on the kinetic mixing parameter $ε$ of a dark photon and the scalar-Higgs mixing angle $\sinθ$, and compared with existing indirect, direct and accelerator limits available, providing a comprehensive picture of the allowed parameter space for light portal DM.

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arXiv2026

Constraining dark matter using 20-year INTEGRAL/IBIS observations I: Primordial black holes

Primordial black holes (PBHs) in the asteroid-mass window remain a viable dark matter candidate. In the lower part of this mass range, Hawking evaporation produces electrons and positrons that generate diffuse hard X-ray emission through inverse Compton (IC) scattering on Galactic radiation fields. We present the first search for this signal using a combined spectral and morphological analysis of the 20-year INTEGRAL/IBIS observations. We construct a physically motivated model of the Galactic hard X-ray background, including IC emission from cosmic-ray electrons and unresolved accreting white dwarfs, and consistently incorporate the IC contribution from PBH evaporation. By exploiting both spatial and spectral information, we improve the separation between a possible PBH signal and astrophysical backgrounds compared to analyses based only on spectral data. We derive constraints on the PBH dark matter fraction over a broad mass range, including extended PBH mass functions and rotating PBHs. We assess the impact of uncertainties in cosmic-ray propagation and the Galactic dark matter density profile, finding that the propagation of low-energy electrons and positrons represents the main source of uncertainty in the predicted signal. Despite these limitations, our results provide competitive constraints over a wide range of PBH masses, highlighting the potential of hard X-ray observations as a complementary probe of evaporating PBHs.

astro-ph.HE↗

arXiv2026

Strong Constraints on Line Signals from Dark Matter Annihilation in a Nearby Subhalo

We present a dedicated search for monochromatic gamma-ray emission from a recently proposed nearby dark matter subhalo candidate. Using nearly 15 years of Fermi-LAT Pass 8 data, we perform a sliding-window search for gamma-ray lines between 10 and 300 GeV. We do not find any statistically significant evidence for a line signal. The largest excess occurs at $E_γ\simeq 28 \, {\rm GeV}$ with a local significance of $2.5σ$. We therefore derive 95% confidence level upper limits on the annihilation cross section for $χχ\rightarrow γγ$. Under the assumed NFW subhalo model, the resulting constraints are stronger than existing Galactic Center line limits over much of the explored mass range. We further translate these line constraints into bounds on well-motivated WIMP models, such as Higgs-portal and Wino dark matter scenarios, restricting previously open parameter regions consistent with thermal freeze-out as well as models associated with dark matter interpretations of the Galactic Center Excess.

hep-ph↗

arXiv2026

Sgr A* as a Galactic PeVatron: Multimessenger Signatures of the Magnetic Penrose Process

The magnetic Penrose process (MPP) is one of the most efficient mechanisms for extracting rotational energy from a magnetized Kerr black hole (BH), enabling charged particles to reach very-high energies. We investigate this process in Sagittarius A* (Sgr A*), the supermassive BH at the Galactic center (GC), focusing on its ultra-high-efficiency regime, in which neutrons undergo beta decay inside the BH ergosphere. As a key novelty, we compute the neutron production spectrum in the accretion flow directly from the nuclear reaction kinematics and follow neutron trajectories in the Kerr spacetime to determine the population that reaches the ergosphere and undergoes the MPP. From this population, we derive the spectrum of accelerated protons and show that Sgr A* can accelerate them up to PeV energies, strengthening its interpretation as a candidate Galactic PeVatron. We further compute the gamma-ray and neutrino emission produced through hadronic interactions of the escaping protons in the Central Molecular Zone. The predicted gamma-ray fluxes exhibit distinctive spectral features that could provide an observational signature of the MPP and may constitute a non-negligible contribution to the very-high-energy emission detected by H.E.S.S. and HAWC. The associated neutrino fluxes remain below the diffuse Galactic component inferred by IceCube, but may still contribute to the high-energy emission from the GC. Remarkably, the predicted signals lie within the projected sensitivity of SWGO for all scenarios considered here and, for some models, only a factor of a few below the nominal CTAO sensitivity, while KM3NeT/ARCA and IceCube-Gen2 will provide complementary tests. Our results establish the MPP as an observable mechanism for extracting BH rotational energy, providing a direct connection between horizon-scale physics and multimessenger observations that can be extended to other magnetized BHs.

astro-ph.HE↗

arXiv2026

Decisive evidence for a global cosmic-ray feature in gamma-ray data

We analyze 17 years of Fermi-LAT data to study the diffuse $γ$-ray emission along the Galactic plane and its connection to cosmic-ray (CR) propagation. Accounting for correlated instrumental systematics, we find decisive evidence for a spectral break at $\sim20-30$ GeV, present across the inner Galactic disk, with a preference of $Δχ^2=39.78$ ($4.44 σ$ global). The energy and amplitude of this feature are in striking agreement with the spectral feature observed in local CR nuclei, indicating that it is a global property of the Galactic disk rather than a local phenomenon. The measured slope change, $Δγ\simeq 0.20$, is consistent with local CR data and with expectations from a transition in the CR diffusion regime from Kolmogorov to Kraichnan turbulence. Our results provide strong evidence that diffuse $γ$-ray emission along the Galactic disk is dominated by $π^0-$decay emission up to a hundred GeV. These findings provide key insights into the origin of the CR spectral hardening and the propagation of CRs throughout the Galaxy, and illustrate how this multimessenger approach can be used to probe the origin of features in the CR spectra, such as the long-studied CR Knee.

astro-ph.HE↗

arXiv2026

Strong Constraints on Millisecond Pulsar Injection Spectra from Fermi-LAT Observations of the Galactic Center

Millisecond pulsars (MSPs) are a leading explanation of the Galactic Center excess (GCE) observed in Fermi-LAT data. We constrain this scenario by jointly modeling prompt and inverse-Compton $γ$ rays from MSP-injected $e^\pm$ on the Galactic bulge, using recent Fermi-LAT GCE spectra from state-of-the-art interstellar emission models and data analysis. Current data place strong upper limits on the efficiency ratio $η_e/η_γ$ across broad $e^\pm$ injection scenarios, surpassing those from globular-cluster observations with MAGIC and competitive with projected CTAO sensitivities toward the Galactic bulge.

astro-ph.HE↗

arXiv2026

INTEGRAL, eROSITA and Voyager Constraints on Light Bosonic Dark Matter: ALPs, Dark Photons, Scalars, $B-L$ and $L_{i}-L_{j}$ Vectors

The decay of light bosonic dark matter particles can produce a bright electron/positron ($e^+e^-$) flux that can be strongly constrained by local Voyager observations of the direct $e^+e^-$ flux, as well as 511 keV Line and X-ray continuum observations of $e^+e^-$ emission. We carefully analyze the $e^+e^-$ yield and resulting cosmic-ray and X-ray spectra from theoretically well-motivated light dark matter models, including: (a) electrophilic axion-like particles, (b) dark photons, (c) scalars, and (d) $B-L$ and $L_{i}-L_{j}$ vector bosons. We use the morphology and spectrum of the INTEGRAL 511 keV line data, the eROSITA X-ray continuum spectrum and the Voyager $e^+e^-$ spectrum to constrain the decay lifetime and coupling of each dark matter model. We find that 511 keV observations typically set world-leading limits on bosonic dark matter decay below masses of $\sim$1 GeV, while eROSITA observations provide the strongest constraints in the range from 1--10 GeV. Finally, we forecast future limits from 21 cm line searches with next-generation HERA data.

hep-ph↗

arXiv2026

Refining Galactic primordial black hole evaporation constraints

We revisit the role of primordial black holes (PBHs) as potential dark matter (DM) candidates, particularly focusing on light asteroid-mass PBHs. These PBHs are expected to emit particles through Hawking evaporation that can generate cosmic rays (CRs), eventually producing other secondary radiations through their propagation in the Milky Way, in addition to prompt emissions. Here, we perform a comprehensive analysis of CR signals resulting from PBH evaporation, incorporating the full CR transport to account for reacceleration and diffusion effects within the Milky Way. In particular, we revisit the $e^\pm$ flux produced by PBHs, using Voyager 1, and study for the first time the diffuse X-ray emission from the up-scattering of Galactic ambient photons due to PBH-produced $e^\pm$ via the inverse Compton effect using XMM-Newton data, as well as the morphological information of the diffuse 511 keV line measured by INTEGRAL/SPI. In doing so, we provide leading constraints on the fraction of DM that can be in form of PBHs in a conservative way, whilst also testing how different assumptions on spin and mass distributions affect our conclusions.

astro-ph.HE↗

arXiv2026

Sub-keV dark matter can strongly ionize molecular clouds

We show that the ionization of dense molecular clouds can be used to set strong constraints on dark matter models producing UV/X-ray photons in their annihilation or decay. We place robust and competitive constraints on various dark matter models, such as axion-like particles, scalars and sterile neutrinos, for masses between $\sim30$~eV and $10$~keV, and project forecasts to illustrate the potential of this target. We discuss how these constraints can be significantly improved by considering a more refined sample of molecular clouds near the Galactic Center and above the Galactic plane, a detailed modeling of the cosmic-ray ionization contribution and, potentially, a more refined analysis of the gas density in clouds through dust extinction maps. Thus, ionization of molecular clouds emerges as one of the most powerful tools for probing sub-keV dark matter.

hep-ph↗

arXiv2026

New 511 keV line data provides strongest sub-GeV dark matter constraints

We explore the $511$~keV emission associated to sub-GeV dark matter (DM) particles that can produce electron-positron pairs and form positronium after thermalizing. We use $\sim16$~yr of SPI data from INTEGRAL to constrain DM properties, considering the full positron propagation and losses, and the free electron density drop away from the Galactic plane. We show that the predicted longitude and latitude profiles vary significantly for different DM masses, unlike previous assumptions, and obtain the strongest limits on sub-GeV DM (from the MeV to a few GeV) so far, excluding cross-sections down to $\langle σv \rangle \lesssim10^{-32}$ cm$^3$ s$^{-1}$ for $m_χ\sim1\,\text{MeV}$ and $\langle σv \rangle \lesssim10^{-26}$ cm$^3$ s$^{-1} $ for $m_χ\sim5\,\text{GeV}$ and lifetimes up to $τ\gtrsim 10^{29}\, \textrm{s} \, (m_χ\sim1\,\text{MeV}) $ and $τ\gtrsim 10^{27}\,\textrm{s}$ ($m_χ\sim5$~GeV) for the typical Navarro-Frenk-White DM profile. Our derived limits are robust within a factor of a few due to systematic uncertainties.

hep-ph↗

arXiv2026

(H)ALPing the 511 keV line: A thermal DM interpretation of the 511 keV emission

We propose a novel framework where MeV-scale Dirac Dark Matter annihilates into axion-like particles, providing a natural explanation for the 511 keV gamma-ray line observed in the Galactic Center. The relic abundance is determined by p-wave annihilation into two axion-like particles, while s-wave annihilation into three axion-like particles, decaying into $e^+ e^-$ pairs, accounts for the line intensity. Remarkably, this model, assuming a standard Navarro-Frenk-White profile, reproduces the observed emission morphology, satisfies in-flight annihilation and cosmological bounds, and achieves the correct relic density, offering a compelling resolution to this longstanding anomaly.

hep-ph↗

arXiv2026

Do the sources of the 511 keV excess explain the anomalous CMZ ionization?

The anomalous rate of molecules ionization observed at the Central Molecular zone (CMZ) challenges known mechanisms of ionization observed in molecular clouds across the Galaxy, due to the exceptionally high levels of ionization measured (orders of magnitude above what cosmic rays can explain) and its uniform spatial distribution within the CMZ. Recent studies suggest that the source of the $511$~keV excess can be correlated with this anomalous ionization rate or contribute significantly to the ionization in the Galactic Centre (GC). One of the leading hypotheses attributes the $511$~keV signal to positron injection from radionuclides or pulsars distributed following the stellar bulge, which is rather flat around the GC and, hence, could help explaining the uniform ionization profile. In this work, we investigate whether such a population of sources, injecting MeV positrons at rates consistent with the $511$~keV observations, can account for the ionization levels and distribution observed in the CMZ. Our results indicate that positron injection alone falls short at explaining the anomaly, although their expected ionization is larger than expected from any previously studied candidates.

astro-ph.HE↗

arXiv2026

The COSMIC WISPers White Paper: The physics case for Weakly Interacting Slim Particles

Axions and other very weakly interacting slim particles (WISPs), with masses below 1 GeV, arise naturally in many extensions of the Standard Model of particle physics. In particular, they could offer a new framework to explain the nature of dark matter and may help address a range of puzzling observations in astrophysics and particle physics. This review provides an overview of ongoing WISP searches and outlines the prospects for the next decade, spanning their theoretical motivation, indirect signatures in astrophysical observations, and dedicated laboratory experiments. It is based on the work carried on by the EU-funded COST Action ``Cosmic WISPers in the Dark Universe: Theory, astrophysics, and experiments'' (CA21106, https://www.cost.eu/actions/CA21106). This network plays a key role in coordinating and supporting WISP searches across Europe, while also contributing to the development of a roadmap aimed at securing European leadership in this research area. It is emphasized that Europe is currently pursuing a rich, diverse, and cost-effective experimental program, with the potential to deliver one or more transformative discoveries.

hep-ph↗

arXiv2026

An Excited Dark Matter Solution to the MeV Galactic Center Excesses

Recent COMPTEL data analysis reveals a $\sim$ 2 MeV continuum excess whose spatial distribution closely matches the long-standing 511 keV line observed by INTEGRAL/SPI, indicating a common population of low-energy positrons that is difficult to reconcile with known astrophysical sources or standard thermal dark matter (DM). We show that a minimal Excited Dark Matter (XDM) model naturally explains these features. In this scenario a DM particle $χ$ is inelastically upscattered into an excited state $χ^*$, followed by de-excitation $χ^*\toχe^+ e^-$ producing $\sim$2 MeV positrons that reproduce the 511 keV line morphology and the COMPTEL MeV continuum. Using a full cosmic-ray (CR) propagation treatment, we obtain an excellent fit for $m_χ\simeq$ 1.5 TeV DM particle with mass-splitting $Δm =m_{χ^*}-m_χ\simeq$ 4 MeV for an inelastic geometric scattering cross section of $σ_\textrm{mr}= 3-4\times 10^{-23}\,\textrm{cm}^2$. The same positrons supply a substantial, radially flat contribution to the anomalous Central Molecular Zone (CMZ) ionization rate. This is the first unified treatment of XDM-induced positrons across all three observables, yielding correlated MeV signatures testable by upcoming missions targeting the Galactic MeV band.

hep-ph↗

arXiv2026

Dark Matter in X-rays: Revised XMM-Newton Limits and New Constraints from eROSITA

We investigate two classes of dark matter (DM) candidates, sub-GeV particles and primordial black holes (PBHs), that can inject low-energy electrons and positrons into the Milky Way and leave observable signatures in the X-ray sky. In the case of sub-GeV DM, annihilation or decay into $e^+e^-$ contributes to the diffuse sea of cosmic-ray (CR) leptons, which can generate bremsstrahlung and inverse Compton (IC) emission on Galactic photon fields, producing a broad spectrum from X-rays to $γ$-rays detectable by instruments such as eROSITA and XMM-Newton. For PBHs with masses below $\sim10^{17}$ g, Hawking evaporation similarly yields low-energy $e^\pm$, leading to comparable diffuse emission. Using the first data release from eROSITA and incorporating up-to-date CR propagation and diffusion parameters, we derive new constraints on both scenarios. For sub-GeV DM, we exclude thermally averaged annihilation cross sections in the range $\sim 10^{-27}-10^{-25} \ \mathrm{cm^3/s}$ and decay lifetimes of $\sim 10^{24}-10^{25}$ s for masses between 1 MeV and 1 GeV, with eROSITA outperforming previous X-ray constraints below $\sim$ 30 MeV. For asteroid-mass PBHs, we set new bounds on the DM fraction based on their Hawking-induced emission. Finally, we revisit earlier constraints from XMM-Newton, finding that they were approximately four orders of magnitude too stringent due to the use of the instrument's geometric solid angle rather than its exposure-weighted solid angle. Upon using the exposure-weighted solid angle, we show that the revised XMM-Newton limits are slightly weaker than those from eROSITA.

hep-ph↗

arXiv2025

Search for Diffuse Galactic Neutrinos with the Full ANTARES Telescope Dataset

The diffuse emission of gamma-rays and neutrinos, produced by interactions of cosmic rays with interstellar matter in the Milky Way, provides valuable insights into cosmic ray propagation and Galactic processes. Emission models incorporating different assumptions about cosmic ray diffusion, source distribution, and target gas density are tested using data from neutrino telescopes. In this study, the final all-flavor neutrino dataset, collected over 15 years (2007--2022) by the ANTARES neutrino telescope, is analyzed. A maximum likelihood ratio method built to handle templates of Galactic emission models is employed to evaluate the compatibility of these models with the observed spatial and energy distributions of neutrino events. The results do not yield stringent constraints on the tested models and upper limits on the diffuse neutrino flux are derived, which are compatible with the results obtained by other experiments.

astro-ph.HE↗

arXiv2025

511 keV Galactic Photons from a Dark Matter Spike

We propose that a dark matter (DM) spike around the Galactic Center's (GC) supermassive black hole, Sgr A*, could account for most of the bulge's measured 511 keV line intensity while remaining cosmologically compatible. DM annihilation can be the primary source of the 511 keV line emission without violating constraints from disk emission observations and in-flight positron annihilation with the interstellar medium, provided the disk emission is dominated by an astrophysical source of low-energy positrons. We find that a DM mass up to approximately 20 MeV, either with a Gondolo-Silk spike or one softened by stellar heating, could explain the observed 511 keV bulge emission profile. Our proposal can be tested by future observations of the continuum diffuse emission close to the GC.

astro-ph.HE↗

arXiv2025

In-flight positron annihilation as a probe of feebly interacting particles

Core-collapse supernovae (SNe) provide a unique environment to study Feebly Interacting Particles (FIPs) such as Axion-Like Particles (ALPs), sterile neutrinos, and Dark Photons (DPs). This paper focuses on heavy FIPs produced in SNe, whose decay produces electrons and positrons, generating observable secondary signals during their propagation and annihilation. We focus on the In-flight Annihilation (IA) of positrons, which emerge as the most significant contribution to the resulting gamma-ray spectrum. Using data from COMPTEL and EGRET we derive the most stringent bounds on the FIP-electron couplings for heavy ALPs, sterile neutrinos, and DPs. These results strenghten existing bounds of one or two orders of magnitude, depending on the FIP model.

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