arXiv subjects

Javier Reynoso-Cordova

Publications and source records attributed to Javier Reynoso-Cordova.

12 recordsLinked to original sources

arXiv2026

LMC-Perturbed LZ Dark Matter Landscape

The local dark matter (DM) velocity distribution is significantly altered by the gravitational impact of the Large Magellanic Cloud (LMC), which creates a high-velocity tail. We evaluate how the LMC reshapes the DM landscape for a wide variety of theoretical models in light of the recent putative LZ DM event. We show that the LMC-induced velocity shifts substantially modify the parameter space for inelastic endothermic DM models across a broad range of possible interactions, driving the viable regions towards larger mass splittings, which are more susceptible to collider and indirect detection constraints. By contrast, models for elastically colliding DM are less impacted, and some remain viable candidates -- for example, the simple light Singlet-Doublet Majorana DM candidate at the Higgs blind spot. Our work confirms that accurately accounting for LMC effects is essential when high-velocity DM is probed, rather than relying on the simplified Standard Halo Model.

hep-ph↗

arXiv2026

Directional dark matter signatures of the Large Magellanic Cloud

The Large Magellanic Cloud (LMC), the most massive satellite of the Milky Way (MW), can significantly perturb the local dark matter (DM) distribution. We study its impact on directional DM detection using the Auriga cosmological simulations of a MW analogue hosting an LMC analogue. We find that the LMC induces strong anisotropies in directional recoil signals, driven primarily by the non-zero mean azimuthal velocity of the local DM distribution. The characteristic ring-like feature predicted in the Standard Halo Model (SHM) for heavy DM and low recoil energies is strongly distorted, producing an asymmetric recoil pattern concentrated at preferred azimuthal angles. Differences between recoil maps for the MW-LMC analogue and the SHM reach up to $\sim80\%$ near the signal maximum. These distortions significantly enhance directional discovery prospects, reducing the number of events required to reject isotropy by nearly a factor of five for a 100 GeV DM particle in a near-future CYGNUS-like experiment, and by even larger factors for heavier DM. Our results highlight the importance of the LMC for interpreting and optimizing future directional DM searches.

hep-ph↗

arXiv2026

Polarized and unpolarized synchrotron emission from dark matter in extragalactic targets

We compute 95% confidence-level upper limits on the dark matter annihilation cross section and decay rate from both total-intensity and polarized synchrotron emission in five extragalactic targets: M31, the Large Magellanic Cloud (LMC), the Draco and Sculptor dwarf spheroidal galaxies, and the Coma cluster. Using Planck maps at 30, 44, and 70 GHz, we solve the diffusion-loss equation for dark-matter-produced electrons and positrons numerically with DRAGON and integrate the resulting synchrotron emission along the line of sight with HERMES, computing both total-intensity and polarized-intensity maps for each target with target-specific magnetic-field, gas, and radiation-field environments. The 30 GHz channel yields the most stringent constraints in all cases, and limits on annihilation or decay into $e^+e^-$ are stronger than those for $b\bar{b}$ due to the harder injected spectrum. For most targets the total-intensity and polarized limits are broadly comparable; the LMC is an exception, where Faraday depolarization in the turbulent disk suppresses the polarized signal relative to total intensity, making total intensity the primary estimator. Our results are robust against the choice of flux estimator and coordinate uncertainty. This work demonstrates that microwave polarimetry provides a complementary and largely independent probe of dark matter synchrotron emission in extragalactic targets.

astro-ph.GA↗

arXiv2025

The diffusion coefficient in the Large Magellanic Cloud

The Large Magellanic Cloud (LMC) is the largest satellite galaxy of the Milky Way and provides a unique laboratory for high-energy astrophysics and dark matter studies. In this work, we develop an end-to-end numerical description of cosmic-ray transport and the associated non-thermal emission in the LMC, extending the public DRAGON and HERMES codes. Within this framework, we compute the diffuse synchrotron radiation produced by cosmic-ray electrons in the LMC and compare our predictions with observed low-frequency radio maps. Because electron diffusion imprints a characteristic morphology on the radio emission, this comparison allows us to infer the effective average diffusion coefficient in the LMC. We find a diffusion coefficient D0 = (3-6) $\times 10^{28} \; \rm{cm}^2 \; \rm{s}^{-1}$ at 1 GeV, comparable to but slightly larger than values typically inferred for the Milky Way. More generally, this work provides a scalable tool for interpreting non-thermal signals in nearby galaxies and constraining their cosmic-ray transport properties.

astro-ph.GA↗

arXiv2024

The Large Magellanic Cloud: expanding the low-mass parameter space of dark matter direct detection

We investigate how the Large Magellanic Cloud (LMC) impacts the predicted signals in near-future direct detection experiments for non-standard dark matter (DM) interactions, using the Auriga cosmological simulations. We extract the local DM distribution of a simulated Milky Way-like halo that has an LMC analogue and study the expected signals in DarkSide-20k, SBC, DARWIN/XLZD, SuperCDMS, NEWS-G, and DarkSPHERE considering DM-nucleon effective interactions, as well as inelastic DM scattering. We find that the LMC causes substantial shifts in direct detection exclusion limits towards smaller cross sections and DM masses for all non-relativistic effective field theory (NREFT) operators, with the impact being highly pronounced for velocity-dependent operators at low DM masses. For inelastic DM, where the DM particle up-scatters to a heavier state, the LMC shifts the direct detection exclusion limits towards larger DM mass splitting and smaller cross sections. Thus, we show that the LMC significantly expands the parameter space that can be probed by direct detection experiments towards smaller DM-nucleon cross sections for all NREFT operators and larger values of mass splitting for inelastic DM.

hep-ph↗

arXiv2024

Robust bounds on ALP dark matter from dwarf spheroidal galaxies in the optical MUSE-Faint survey

Nearby dwarf spheroidal galaxies are ideal targets in the search for indirect dark matter (DM) signals. In this work, we analyze MUSE spectroscopic observations of a sample of five galaxies, composed of both classical and ultra-faint dwarf spheroidals. The goal is to search for radiative decays of axion-like particles (ALPs) in the mass range of 2.7-5.3 eV. After taking into account the uncertainties associated with the DM spatial distribution in the galaxies, we derive robust bounds on the effective ALP-two-photon coupling. They lie well below the QCD axion band and are significantly more constraining than limits from other probes, in the relevant mass range. We also test the possible presence of a positive signal, concluding that none of the channels selected for this analysis, i.e., not affected by large background contamination, is exhibiting such evidence.

astro-ph.CO↗

arXiv2023

The self-confinement of electrons and positrons from dark matter

Radiative emissions from electrons and positrons generated by dark matter (DM) annihilation or decay are one of the most investigated signals in indirect searches of WIMPs. Ideal targets must have large ratio of DM to baryonic matter. However, such ``dark'' systems have a poorly known level of magnetic turbulence, which determines the residence time of the electrons and positrons and therefore also the strength of the expected signal. This typically leads to significant uncertainties in the derived DM bounds. In a novel approach, we compute the self-confinement of the DM-induced electrons and positrons. Indeed, they themselves generate irregularities in the magnetic field, thus setting a lower limit on the presence of the magnetic turbulence. We specifically apply this approach to dwarf spheroidal galaxies. Finally, by comparing the expected synchrotron emission with radio data from the direction of the Draco galaxy collected at the Giant Metre Radio Telescope, we show that the proposed approach can be used to set robust and competitive bounds on WIMP DM.

astro-ph.HE↗

arXiv2023

Could compact stars in globular clusters constrain dark matter?

The dark matter content of globular clusters, highly compact gravity-bound stellar systems, is unknown. It is also generally unknow*able*, due to their mass-to-light ratios typically ranging between 1$-$3 in solar units, accommodating a dynamical mass of dark matter at best comparable to the stellar mass. That said, recent claims in the literature assume densities of dark matter around 1000 GeV/cm$^3$ to set constraints on its capture and annihilation in white dwarfs residing in the globular cluster M4, and to study a number of other effects of dark matter on compact stars. Motivated by these studies, we use measurements of stellar kinematics and luminosities in M4 to look for a dark matter component via a spherical Jeans analysis; we find no evidence for it, and set the first empirical limits on M4's dark matter distribution. Our density upper limits, a few $\times \ 10^4$ GeV/cm$^3$ at 1 parsec from the center of M4, do not negate the claims (nor confirm them), but do preclude the use of M4 for setting limits on non-annihilating dark matter kinetically heating white dwarfs, which require at least $10^5$ GeV/cm$^3$ densities. The non-robust nature of globular clusters as dynamical systems, combined with evidence showing that they may originate from molecular gas clouds in the absence of dark matter, make them unsuitable as laboratories to unveil dark matter's microscopic nature in current or planned observations.

astro-ph.HE↗

arXiv2022

Upper limits on the dark matter content in globular clusters

We present a systematic analysis on the possible presence of dark mass components inside globular clusters (GCs). A spherical Jeans analysis is applied to the stellar kinematics of 9 nearby GCs. On top of the mass distribution provided by the luminous stellar component, we add either dark matter (DM), described by an NFW mass profile, or an intermediate mass black-hole (IMBH), described by a point-like mass. Their existence would have important implications in the context of indirect DM searches. After profiling over the stellar parameters, we find no evidence neither for DM nor for IMBH. Upper limits on the two components are reported.

astro-ph.GA↗

arXiv2021

The EMU view of the Large Magellanic Cloud: Troubles for sub-TeV WIMPs

We present a radio search for WIMP dark matter in the Large Magellanic Cloud (LMC). We make use of a recent deep image of the LMC obtained from observations of the Australian Square Kilometre Array Pathfinder (ASKAP), and processed as part of the Evolutionary Map of the Universe (EMU) survey. LMC is an extremely promising target for WIMP searches at radio frequencies because of the large J-factor and the presence of a substantial magnetic field. We detect no evidence for emission arising from WIMP annihilations and derive stringent bounds on the annihilation rate as a function of the WIMP mass, for different annihilation channels. This work excludes the thermal cross section for masses below 480 GeV and annihilation into quarks.

astro-ph.HE↗

arXiv2019

On the origin of the gamma-ray emission from Omega Centauri: Milisecond pulsars and dark matter annihilation

We explore two possible scenarios to explain the observed gamma-ray emission associated with the atypical globular cluster Omega-Centauri: emission from millisecond pulsars (MSP) and dark matter (DM) annihilation. In the first case the total number of MSPs needed to produce the gamma-ray flux is compatible with the known (but not confirmed) MSP candidates observed in X-rays. A DM interpretation is motivated by the possibility of Omega-Centauri being the remnant core of an ancient dwarf galaxy hosting a surviving DM component. At least two annihilation channels, light quarks and muons, can plausibly produce the observed gama-ray spectrum. We outline constraints on the parameter space of DM mass versus the product of the pair-annihilation cross section and integrated squared DM density (the so-called J-factor). We translate upper limits on the dark matter content of Omega-Centauri into lower limits on the annihilation cross section. This shows s-wave annihilation into muons to be inconsistent with CMB observations, while a small window for annihilation into light quarks is allowed. Further analysis of Omega-Centauri's internal kinematics, and/or additional information on the resident MSP population will yield much stronger constraints and shed light about the origin of this otherwise mysterious gamma-ray source.

astro-ph.HE↗

arXiv2018

Lessons from HAWC PWNe observations: the diffusion constant is not a constant; Pulsars remain the likeliest sources of the anomalous positron fraction; Cosmic rays are trapped for long periods of time in pockets of inefficient diffusion

Recent TeV observations of nearby pulsars with the HAWC telescope have been interpreted as evidence that the diffusion of high-energy electrons and positrons within pulsar wind nebulae is highly inefficient compared to the rest of the interstellar medium. If the diffusion coefficient well outside the nebula is close to the value inferred for the region inside the nebula, high-energy electrons and positrons produced by the two observed pulsars could not contribute significantly to the local measured cosmic-ray flux. The HAWC Collaboration thus concluded that, under the assumption of isotropic and homogeneous diffusion, the two pulsars are ruled out as sources of the anomalous high-energy positron flux. Here, we argue that since the diffusion coefficient is likely not spatially homogeneous, the assumption leading to this conclusion is flawed. We solve the diffusion equation with a radially dependent diffusion coefficient, and show that the pulsars observed by HAWC produce potentially perfect matches to the observed high-energy positron fluxes. We also study the implications of inefficient diffusion within pulsar wind nebulae on Galactic scales, and show that cosmic rays are likely to have very long residence times in regions of inefficient diffusion. We describe how this prediction can be tested with studies of the diffuse Galactic emission.

astro-ph.HE↗