CLAF/ICTP-SAIFR Latin-American Astroparticle Physics School

List of participants here.

There is no registration fee and limited funds are available for travel and local expenses.

Announcement:

Application deadline: June 6, 2025 (closed)

Lectures

• Rafael Alves-Batista (IAP, France)

• Gustavo Romero (IAR, Argentina)

• Michele Doro (INFN and University of Padova, Italy)

• Elisabetta Bissaldi (INFN and University of Bari, Italy)

• Felix Aharonian (DIAS, Ireland) : Overview of Ground-based Gamma-ray Astronomy
• Shoushan Zhang (IHEP, China) : Introduction to Extensive Air-Shower Arrays and LHAASO
  
• Ulisses Barres de Almeida (CBPF, Brazil) : The Southern Wide-Field Gamma-ray Observatory, SWGO

• Raniere de Menezes (CBPF, Brazil):
  Session 1 – Stereoscopic analysis of the Crab Nebula with Imaging atmospheric Cherenkov telescopes
  Session 2 – The Galactic center above 1 TeV: simulations with the SWGO science tools
  Session 3 – Analysis of a BL Lac object over 5 decades of energy with Fermi-LAT, CTA and SWGO

  Please download the following files: material.zip, IACT_simulated_data.zip
  Please install easyfermi following this tutorial.

POSTERS I (August 11-13) 

• • Abaroa, Leandro (Instituto Argentino de Radioastronomía – Universidad Nacional de La Plata, Argentina): Microquasar remnants as PeVatrons

In microquasars (MQs), the jet head propagates through the interstellar medium, inflating the cocoon that surrounds the entire system. Both the base and the terminal region of the jets are shock-prone regions where particles are accelerated to relativistic energies. Under certain conditions, the mass transfer from the star to the black hole can be permanently interrupted. The MQ remnant continues to inject very high and ultrahigh energy cosmic rays into the environment after the MQ has shut down, contributing to the internal overpressure of the cocoon and thus to its expansion. If the MQ remnant is in a star-forming region, large clumps can enter the cocoon. Cosmic rays will interact with these clumps, illuminating them through pp interactions. In this work we investigate whether these remnants can be detected and whether they are hidden PeVatron sources. We present some preliminary results on the physics of the cocoon and the injection of cosmic rays.

• • Alvarez Hernández, Marcos Alejandro (Instituto Superior de Tecnologías y Ciencias Aplicadas, Universidad de la Habana, Cuba): On magnetized Bose-Einstein charged scalar condensate stars

We study the thermodynamic properties of non-interacting charged scalar boson gas in the presence of an external magnetic field considering statistical and vacuum contribution. We get the most important properties of the gas at arbitrary values of the magnetic field. In particular at low temperature: the Bose-Einstein condensation (BEC), magnetic properties, and equation of state (EoS) are investigated. The EoS exhibits anisotropies with splitting of pressures into parallel and perpendicular components relative to the magnetic field direction. The perpendicular pressure eventually displays quantum magnetic collapse similar to fermionic gases. The contribution of antiparticles is to enhance the specific heat beyond 3/2, magnetization, and total pressure. Astrophysical implications of these phenomena are discussed.

• • Alves, Gustavo Figueiredo Severiano (Institute of Physics University of Sao Paulo, Brazil): Chasing Serendipity: Tackling Transient Sources with Neutrino Telescopes

The discovery of ultra-high-energy neutrinos by IceCube marked the beginning of neutrino astronomy. Yet, the origin and production mechanisms of these neutrinos remain open questions. With the recent observation of the highest-energy neutrino event to date by the KM3NeT collaboration, transient sources—astrophysical objects that emit particles in brief, localized bursts—have emerged as promising candidates. In this work, we revisit the identification of such sources in IceCube and future neutrino telescopes, focusing on how both the timing and sky localization of the source affect the detection sensitivity. We highlight the crucial role of the source’s right ascension in determining the effective area of detectors not located at the poles, such as KM3NeT, and present a framework to consistently account for this dependence. As a case study, we investigate evaporating primordial black holes (PBHs) as transient neutrino sources, showing that the detection prospects and localization accuracy are strongly influenced by the PBH’s position in the sky. Our results emphasize the complementarity between neutrino and gamma-ray observatories and showcase the potential of a global network of neutrino detectors to identify and localize transient events that might be missed by traditional photon-based instruments.

• • Bastos, Victor (Instituto de Física de São Carlos(IFSC) – Universidade de São Paulo (USP), Brazil): Study of Ultra-High-Energy Cosmic Ray Propagation and Air Shower Formation

Over the years, numerous observatories have been built to detect different regions of the cosmic energy spectrum, including the highest energies originating from deep space. The most energetic of these particles are classified as ultra-high-energy cosmic rays (UHECRs), primarily composed of protons and heavier nuclei, with energies at or above 1 EeV. Identifying the sources of UHECRs remains a significant challenge, mainly due to the deflection they experience from magnetic fields both during propagation and potentially at their acceleration sites. Despite this difficulty, some observatories—such as the Pierre Auger Observatory—are dedicated to tracing their possible origins. The objective of this work is to compare observational data from the Pierre Auger Observatory with results from Monte Carlo simulations that model the full trajectory of UHECRs, from their sources to Earth. For this purpose, I use CRPropa to simulate cosmic ray propagation through space, and both CORSIKA and FLUKA to simulate the resulting air showers generated when these particles interact with Earth’s atmosphere. By combining data from the Pierre Auger Offline framework with the outputs of these simulations, the goal is to reconstruct a model of UHECR trajectories that closely matches observational results. Such a model could eventually be used to more reliably infer the origins of detected UHECRs.

• • Bernardo da Silva, Samuel Victor (Universidade Federal de Campina Grande, Brazil): Exploring Bethe–Heitler Induced Cascades in Flaring Episodes of the TeV Blazar 1ES 1959+650

Blazars are a subclass of active galactic nuclei (AGN) with relativistic jets aligned closely to the observer’s line of sight, producing non-thermal spectral energy distributions (SEDs) characterized by two broad components: a low-energy peak (radio to UV/X-rays) and a high-energy peak (X-rays to gamma rays). While the low-energy emission is attributed to synchrotron radiation from relativistic electrons in the jet, the origin of the high-energy component remains debated, with both leptonic and hadronic processes under consideration. In this work, we present updated models of the SED for the blazar high-frequency-peaked BL Lac object (HBLs) 1ES 1959+650. The hard gamma-ray spectra observed during its flaring state suggest the presence of an additional emission component beyond the standard synchrotron self-Compton (SSC) scenario. We explore the possibility that this hard gamma-ray emission arises from inverse Compton (IC) scattering by Bethe-Heitler pairs produced along the line of sight, pointing to a more complex high-energy emission mechanism in these sources.

• • Bonilla Rivera, Alexander (Instituto de Física, Universidade Federal Fluminense, Colombia): VSL-Gravity in light of PSR B1913+16 full data set: Upper limits on graviton mass and its theoretical consequences

Very Special Linear Gravity (VSL-Gravity) is an alternative model of linearized gravity that incorporates massive gravitons while retaining only two physical degrees of freedom thanks to gauge invariance. Recently, the gravitational period-decay dynamics of the model has been determined using effective field theory techniques. In this study, we conduct a comprehensive Bayesian analysis of the PSR B1913+16 binary pulsar dataset to test the predictions of VSL-Gravity. Our results place a 95% confidence level upper bound on the graviton mass at m_g < 10^{-19} eV/c^2. Additionally, we observe a significant discrepancy in the predicted mass of one of the binary’s companion stars. Lastly, we discuss the broader implications of a non-zero graviton mass, from astrophysical consequences to potential cosmological effects.

• • Capellini, Gabriel Cassoli (Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Brazil): The role of a jet-outflow system in gamma-ray emission from a protoplanetary nebula

Recently, a multiwavelength study suggested an association between a Fermi-LAT source and a protoplanetary nebula, unveiling the possibility of a new type of high-energy emitter. In this source a jet-outflow morphology was revealed by radio and X-ray observations, along with the detection of a redshifted CO molecular outflow. According to the current theoretical framework, this could result from the interaction between the protoplanetary jet and a molecular outflow with the ambient gas in the stellar system, producing shocks that accelerate particles via the first-order Fermi mechanism. Given this new scenario, we developed a radiative model of the source aiming to reproduce the multiwavelength spectrum. We fitted the spectrum using a Monte Carlo algorithm to determine the best-fit parameters describing the detection. Finally, we implemented a jet model to explain the gamma-ray emission. Through this analysis, we were able to constrain the physical conditions in the source necessary to explain the gamma-ray detection. We conclude that this source is an ideal opportunity to study jets associated with planetary nebulae as potential gamma-ray emitters.

• • Carvalho, Augusto (IAG-USP, Brazil): Cosmic ray transport and acceleration in shocks from stellar winds in the Milky Way

This work focuses on modelling cosmic ray transport and acceleration in shocks from stellar winds from runaway stars. These are stars that were ejected from their birth places due to extreme events, such as a super nova explosion or due to gravitational instabilities. They travel space with velocities higher than 30 km/s, developing shocks in their interaction with the interstellar medium. These shocks are believed to be one of the mechanisms that accelerate CRs within the Milky Way. We model the system via 3D-MHD simulations with PLUTO software. In a latter stage, we inject particles via particle-in-cell simulations using the in-house BUTANTAN code, aiming to assess and evaluate the diffusive transport in the interaction with the bowshock system and in the presence of radiative cooling.

• • Chalbaud, Esteban Ricardo (Laboratório de Instrumentação e Física Experimental de Partículas, Portugal): Asymmetries in invisible Dark Matter mediator production associated with $t \bar{t}$ final states

We employ a Dark Matter simplified model that couples a scalar mediator with top quarks. The reconstruction of the kinematic variables is presented at NLO accuracy for events associated with this massive scalar particle, which is assumed to be vanishing to invisible decays in a detector such as ATLAS. We build these observables by taking advantage of the similarity between the scalar coupling with the top quark and the factorization theorem in the total scattering amplitude, in order to represent the basis in which the phase space is parameterized. A twofold approach employs the direct implementation of the four-momentum phase space measure in building CP sensitive observables such as $b_{2}$ for the Higgs, and the spin polarization of the top-quark decays in the narrow width approximation for the employed model. We studied the asymmetries of these distributions to test for any improvement in increasing the exclusion region for the $g_{u_{33}}^S-g_{u_{33}}^P$ parameters associated with this vanishing scalar particle. Considering the case of an invisible mediator with mass of 10$^{-2}$~GeV for a luminosity of 300~fb$^{-1}$ expected at the end of Run 3, the best limits for $g_{u_{33}}^S$ and $g_{u_{33}}^P$ at NLO accuracy were obtained using the variables $\tilde{b}_{2}^{\widehat{y}}$ and $b_{2}$ respectively, with corresponding limits set to $[−0.0425, 0.0425] $ and $[−0.83, 0.83]$ at $68\%$ CL.

• • Cordeiro, Giovanna (Instituto de Física da Universidade de São Paulo, Brazil): A study of the reconstruction of the BL Lacs Luminosity Function and their spectral parameters with the Fermi-LAT telescope

Blazars, a subclass of Active Galactic Nuclei (AGNs), are among the most luminous and energetic objects in the Universe, powered by accretion onto supermassive black holes (SMBHs). In this work, we focus on the gamma-ray luminosity function (GLF) of BL Lacertae objects (BL Lacs), a type of blazar. We started by generating a synthetic catalog of BL Lacs sampling from the Luminosity-Dependent Density Evolution (LDDE) parameterization of the GLF, whose 12 parameters have been previously tuned to the Fermi Large Area Telescope (Fermi-LAT) first year data set. The sampling was performed by a Markov Chain Monte Carlo (MCMC) and included cosmological expansion effects. To assess the impact of instrumental effects on the reconstruction of the GLF, we performed a detailed simulation of a full sky Fermi-LAT survey. This simulation, along with the subsequent analysis, was conducted using the Fermi Science Tools (Fermitools), incorporating different diffuse background components (galactic and extragalactic) and flux cuts to evaluate biases in the reconstruction of the BL Lacs parametric power-law model. Our findings indicate that higher flux cuts and longer exposure times improve parameter estimation, and that the presence of the Galactic component strongly influences the reconstruction quality when the spectral distribution of this diffuse background is treated as a pure power-law. We have also explored the resolution limit on the determination of the BL Lacs GLF by reconstructing the posterior distributions of the LDDE parameters using an input catalog containing the total number of objects predicted by the model in the luminosity range $10^{44}$ erg s$^{-1}$ – $10^{52}$ erg s$^{-1}$. We find that 6 of the parameters in this optimistic scenario are already hard to constrain. Future steps include incorporating detection efficiency, reconstructing parameters using real data from the Fermi Large Area Telescope, and leveraging the upcoming observations of the planned Cherenkov Telescope Array (CTA) extragalactic survey to improve the accuracy and precision of the GLF parameterization.

• • Costa, Barbara Sales (Universidade de São Paulo – USP, Brazil): Characterization of a DD-fusion-based neutron generator

The composition of Dark Matter (DM) remains a mystery that has challenged science since the last century. The DarkSide-20k collaboration (DS-collab) is one of the experiments pursuing direct detection, using Liquid Argon (LAr) as a target to search for weak interactions beyond the Standard Model of Particle Physics. Most direct detection experiments were initially optimized to search for DM particles with masses around 10 GeV/c2, a region that has been extensively explored. However, since no detection has been confirmed so far, the need to investigate lower mass ranges has become increasingly important. In this context, the ReD experiment (within the DS-collaboration) has been studying the LAr response to low-energy signals corresponding to DM masses below 10 GeV/c2, among other efforts to improve the detector’s sensitivity. To perform this study, we use neutron sources, as they can mimic DM signals. The next phase of ReD, called ReD+, will use a monoenergetic neutron beam from a Deuterium-Deuterium reaction-based Generator (DD-NG), which is currently being commissioned and characterized at the Universidade de São Paulo (USP). This instrumentation work is essential for accurately understanding the properties of the generated neutron beam. In this contribution, we present the current status of the work being carried out at USP with the DD-NG. We present the experimental setup and the calibration and optimization of the detectors, and more specifically of the plastic scintillator to be used for particle identification via pulse shape discrimination techniques.

• • Cruz Carpio, Carlos Andrés (Universidad Mayor de San Andrés, UMSA, Bolivia): Enhancing Detection Efficiency in Water Cherenkov Detectors: A Geant4 Study of Reflective Structures for ALPACA

Improving the detection efficiency of ground-based cosmic-ray detectors is crucial for advancing our understanding of high-energy astrophysical phenomena. In this study, we investigate the potential of integrating a highly reflective, funnel-shaped structure around photomultiplier tubes (PMTs) to enhance the photon collection efficiency in a Water Cherenkov Array, within the context of the ALPACA experiment. Using detailed Geant4 simulations, we model a single detector unit to assess how variations in the funnel’s geometrical parameters affect detection efficiency. Preliminary results indicate that optimizing the funnel design can significantly influence photon collection, offering a promising path toward improved angular resolution. This work serves as a foundational step for future full-array studies and experimental validation

• • DA SILVA, Derlei Jurandir (Universidade Tecnológica Federal do Paraná, Brazil): Convolutional Neural Networks for Stereoscopic Event Classification in CTAO’s Large-Sized Telescopes

Imaging Atmospheric Cherenkov Telescopes (IACTs), such as HESS, MAGIC, VERITAS, and the upcoming Cherenkov Telescope Array Observatory (CTAO), are crucial for observing Very High-energy gamma rays. Unlike charged cosmic rays, these gamma rays travel undeflected from their sources, carrying direct information about extreme astrophysical environments. A primary challenge in IACT data analysis is the separation of gamma-ray initiated extensive air showers (EAS) from the significantly more abundant hadronic EAS background. This work explores the application of deep learning, specifically Convolutional Neural Networks (CNNs), to enhance the gamma/hadron classification. We generated a training dataset through Monte Carlo simulations, first employing CORSIKA to simulate EAS initiated by primary gamma rays and protons. Subsequently, the sim_telarray package was used to simulate the detector response to Cherenkov light in an array of CTAO’s Large-Sized Telescopes (LSTs), producing stereoscopic data for each event. These simulated stereoscopic data were used to train a CNN architecture. The model achieved an accuracy exceeding 90% in distinguishing between gamma-ray and hadron-initiated showers. This result highlights the potential of CNN-based approaches, especially when combined with stereoscopic observations from next-generation instruments like CTAO, potentially advancing the sensitivity of gamma-ray astronomy.

• • Dedin Neto, Pedro (Gleb Wataghin Institute of Physics (IFGW – Unicamp), Brazil): SN1987A neutrino burst: limits on flavor conversion

In this paper, we revisit the SN1987A neutrino data to see its constraints on flavor conversion. We are motivated by the fact that most works that analyze this data consider a specific conversion mechanism, such as the MSW (Mikheyev–Smirnov–Wolfenstein) effect, although flavor conversion is still an open question in supernovae due to the presence of neutrino-neutrino interactions. In our analysis, instead of considering a specific conversion mechanism, we let the electron antineutrino survival probability $P_{\overline{e}\overline{e}}$ be a free parameter. We fit the data from Kamiokande-II, Baksan, and IMB detected spectrum with two classes of models: time-integrated and time-dependent. For the time-integrated model, it is not possible to put limits above $1\sigma$ (68\% confidence level) on the survival probability. The same happens for the time-dependent model when cooling is the only mechanism of antineutrino emission. However, for models considering an accretion phase, $P_{\overline{e}\overline{e}}\sim0$ is strongly rejected, showing a preference for the existence of an accretion component in the detected antineutrino flux, and a preference for normal mass ordering when only the MSW is present.

• • Duran Gonzales, Jesus Andres (Universisdad Mayor de San Simon, Bolivia): Monte Carlo GEANT4 simulations of secondary cosmic ray energy spectra and enviromental dosimetry at mountain altitude(5240 m.a.s.l) for the SAMADHA experiment

This research addresses the physics phenomenon of Cosmic Rays in the Earth’s atmosphere, focusing on computational simulation using the Monte Carlo statistical method to calculate the energy spectrum and the Environmental Dose Equivalent of secondary cosmic rays that reach the Earth’s surface at mountain altitudes.Using the GEANT4 framework, a program was developed to simulate, through the Monte Carlo method, the interaction of primary cosmic rays with the atmosphere at the SAMADHA project stations located in Chacaltaya (Bolivia) and Testa Grigia (Italy), during the peak of solar cycle 25 (2020-2024). The secondary cosmic rays recorded were: [, , ± , ± ] . These particles that reached the sensitive detector were recorded in a .root output file, which was subsequently analyzed, sorted, and scaled using the ROOT framework.This process allowed obtaining the final results, which show an expected behavior: the intensity of the energy spectrum flux and the calculated Environmental Dose Equivalent in Chacaltaya is approximately double that recorded in Testa Grigia. This result is consistent with the Monte Carlo simulations and the experimental data from the SAMADHA experiment and is explained by the lesser amount of atmosphere that secondary cosmic rays must traverse in Chacaltaya (5230 m.a.s.l.) compared to Testa Grigia (3480 m.a.s.l.). The comparison of the calculated Environmental Dose Equivalent with the SAMADHA data found a percentage difference of less than 10%, validating the accuracy of the model used. This study not only contributes to the understanding of the interaction of cosmic rays with the atmosphere but also provides a robust computational tool with a reliable statistical method for estimating the energy spectra and Environmental Dose Equivalent of secondary cosmic rays at high altitudes. Its practical applications include environmental radiation monitoring, radiological safety, and the design of cosmic radiation detectors in different environments. Keywords: Monte Carlo Simulation, Cosmic Rays, GEANT4, ROOT, Dosimetry.

• • Dutta, Samik (Universidade Federal do Espírito Santo, India): Multiple Emission Regions in Jets of the Low-Luminosity Active Galactic Nucleus in NGC 4278

The Large High Altitude Air Shower Observatory (LHAASO) has detected very-high-energy gamma rays from the low-ionization nuclear emission-line region galaxy NGC 4278, which has a low-luminosity active galactic nucleus (LLAGN) and symmetric, mildly relativistic S-shaped twin jets detected by radio observations. Few LLAGNs have been detected in gamma rays due to their faintness. Earlier, several radio-emitting components were detected in the jets of NGC 4278. We model their radio emission with synchrotron emission of ultra-relativistic electrons to estimate the strength of the magnetic field inside these components within a time-dependent framework after including the ages of the different components. We show that the synchrotron and synchrotron self-Compton emission by these components cannot explain the Swift X-ray data and the LHAASO gamma-ray data from NGC 4278. We suggest that a separate component in one of the jets is responsible for the high-energy emission, whose age, size, magnetic field, and the spectrum of the ultra-relativistic electrons inside it have been estimated after fitting the multiwavelength data of NGC 4278 with the sum of the spectral energy distributions from the radio components and the high-energy component. We note that the radio components of NGC 4278 are larger than the high-energy component, which has also been observed in several high-luminosity active galactic nuclei. (arXiv:2405.15657 or ApJ 974, 56)

• • Eduardo, Bruno Siqueira (Institute of Physics – University of Sao Paulo, Brazil): Higher-Spin Dark Matter Meets Hilbert Series: Counting Interactions to Even Higher Orders

An effective Lagrangian is composed of all higher dimensional operators that are Lorentz singlets and invariant under the gauge symmetries of the theory, suppressed by powers of the cutoff. A challenging problem is the construction of the EFT operators, since the number of possibilities grows extremely fast. Furthermore, many of these operators are linearly dependent or can even be discarded, through field redefinitions which make use of equations of motion (EOM) or integration by parts (IBP). Therefore, the number of independent operators of a certain type at some order in an EFT is an extremely useful information, and it turns out one can obtain it precisely by employing the Hilbert Series, a tool from Invariant Algebra that allows one to count invariants in an EFT. In this work, we perform the operator counting of the EFT of the Standard Model aided with a higher-spin Dark Matter particle, up to mass dimension 12.

• • Escalona Contreras, Patricio Nicolás (Universidade Federal da Paraíba, Brazil): Meson Mixing Bounds on Z’ Mass in the Alignment Limit: Establishing the Phenomenological Viability of the 331 Model

We perform a systematic study of flavor-changing neutral currents (FCNCs) in the 331 model with right-handed neutrinos (331RHNs), analyzing constraints on the Z′ boson mass from K-, D-, Bd-, and Bs-meson oscillations. By explicitly incorporating scalar sector dynamics and quark rotation ambiguities, we demonstrate that Z′ mass limits depend critically on the parametrization of Cabibbo-Kobayashi-Maskawa (CKM) matrix factors. We derive lower bounds as low as 472 GeV for the mass of the exotic Z’.

• • Galdamez Silva, Sital Andrea (Universidad de El Salvador, El Salvador): Surface characterization of bodies in the main asteroid belt of the Solar System

This project aims to develop an integrated model for the surface characterization of main-belt asteroids by combining photometric and polarimetric data. The underlying assumption is that a deeper understanding of asteroid surfaces enhances taxonomic classification systems and contributes to the study of Solar System formation processes. The study uses public databases and validated techniques, focusing on correlating surface physical properties with observables such as albedo, phase curves, and polarimetric parameters. These findings underscore the need for multidisciplinary approaches to characterize small bodies without relying on in situ missions.

• • Gambini, Guillermo Geraro Rivera (Universidad Nacional de Ingenieria, Peru): Constraining gamma-ray lines from dark matter annihilation using Fermi-LAT and H.E.S.S. data

Analyzing 14 years of Fermi‑LAT and 10 years of H.E.S.S. observations toward the Galactic Center, we set limits on gamma‑ray lines from fermionic and scalar dark matter annihilations. By modeling gamma-gamma and gamma-Z final states with dimension-5 and -6 effective operators and folding in each instrument’s energy resolution, we constrain the operator scale versus dark matter mass between 10 GeV and 10 TeV.

• • Gomez Alzate, Andres Felipe (Universidad de Antioquia, Colombia): Exploring FOPT in QCD-like theories

In this work, we explore how a θ-term, induced by instanton effects in the vacuum of QCD-like theories, can lead to a first-order phase transition (FOPT) associated with the spontaneous breaking of chiral symmetry. We show that for values θ∼π, the theory exhibits a FOPT. The analysis is carried out using the three-flavor linear sigma model coupled to quarks (LSMq), where the thermal contributions to the effective potential arise from quark-meson interactions. We compute the resulting gravitational wave spectrum and discuss how, if this sector lies within a dark sector, it could account for the stochastic signal reported by NANOGrav. The predicted signal also falls within the sensitivity range of future experiments such as LISA.

• • Gouvêa, Marcela (Brazilian Center for Physics Research (CBPF), Brazil): 1FLAC: a Firmamento-based catalog of AGN in Fermi-LAT high Galactic latitude γ-ray sources

We present the results of a study on high-Galactic latitude γ-ray sources from the Fermi-LAT 4FGL-DR4 catalog, focusing on the search for blazar and other AGN counterparts. The work, carried out independently of the Fermi-LAT team, was performed using Firmamento, a web-based platform designed for the discovery and detailed analysis of multi-frequency sources. The main goal is to provide a new evaluation of the AGN counterparts of 4FGL-DR4 γ-ray sources, utilizing novel methods and taking advantage of recently released multi-frequency data. Our results agree with those of the Fermi-LAT catalogs, 4FGL-DR4 or 4LAC-DR3, in over 85% of cases. However, though limited in percentage, the discrepancies are of considerable importance. In particular, we have been able to find robust blazar identifications, based on unambiguous SEDs, for 415 previously unassociated γ-ray sources, reducing the fraction of still unidentified extragalactic Fermi-LAT sources by approximately one third, to 17.2%. Additionally, for 62 sources we found a more reliable association than in 4FGL-DR4, and in 51 cases we were unable to confirm the 4FGL-DR4 identification. Using machine learning and infrared-based-methods, we estimated the synchrotron peak energy and peak flux of the Spectral Energy Distribution of the blazar counterparts in a consistent and automated manner, minimizing human intervention. Most of our peak energy estimates agree within a factor of a few with those in the 4LAC-DR3 catalog, but they deviate by two to four orders of magnitude for a few dozen sources. We named the catalog including all our results 1FLAC (First Firmamento LAT AGN Catalog), which will be available online via the Firmamento platform. The simplicity of use and the commitment to educational engagement of Firmamento enabled active participation from both graduate and undergraduate students in this project.

• • Jiménez Cardona, Ferney Andrés (Universidad del Valle, Colombia): Chameleon Mechanisms in Modified Gravity f(R) Models

Explaining the accelerated expansion of the universe remains one of the greatest challenges in modern cosmology. Although the cosmological constant is the simplest model to account for observational data, it faces the well-known fine-tuning problem. Modified gravity of the form f(R) offers an alternative approach to addressing the dark energy problem. This framework exhibits characteristic effects on both cosmological and local scales, which can distinguish it clearly from other dark energy models, including the cosmological constant. One such effect, known as the chameleon effect, is the focus of this project. We aim to examine the formalism and implications of this effect in specific f(R) models.

• • Jiménez Román, Juan Felipe (Physics Institute UNAM (National Autonomous University of Mexico), Mexico): Dark Matter Phenomenology in the Non-Abelian Hidden Model

The present work analyzes the phenomenology of the vector dark matter model, which introduces a hidden symmetry, $SU(2){HS}$, in the \textit{BSM} sector via a scalar doublet $\Phi$, similar to the Higgs boson, with an identical potential that exhibits a global $SO(4)$ symmetry. This scalar doublet interacts with the Higgs boson and acquires a vacuum expectation value $v\phi$, leading to the spontaneous breaking of $SU(2){HS}$ and providing mass to the \textit{BSM} gauge bosons $A^{i}{\mu}$. The symmetry breaking induces a transition from $SO(4)$ to $SO(3)$, creating a custodial symmetry that guarantees the mass degeneracy and stability of the \textit{BSM} gauge bosons, while preventing interactions with SM fermions, making them strong dark matter candidates. The analysis focuses on two key observables: the relic density of dark matter and the direct detection cross-section, which measures the scattering of dark matter particles with nucleons. Using publicly available numerical tools, the model’s parameter space was explored to identify regions where its predictions match observations from experiments like XENON-1T, PLANCK, and LHC data on the Higgs boson’s mass and couplings. Additionally, the study examined whether the second scalar predicted by the model has been ruled out in collider experiments, along with theoretical constraints like unitarity and potential stability. This analysis enabled the construction of the model’s likelihood profile, concluding that the model can account for dark matter abundance, either partially or fully, and has potential for detection in future experiments.

• • Leon Dueñas, Limber Lorgio (Universidad Mayor de San Andres, Bolivia): Exploration of Nonlinear Structures in Neutron Monitor 12-NM64 Time Series Using Recurrence Plots.

Neutron monitors provide continuous time series that reflect variations in galactic cosmic rays modulated by solar activity and geomagnetic conditions. In this study, we perform an exploratory analysis of data from an NM64-type neutron monitor with a temporal resolution of 10 seconds, using Recurrence Plots (RPs) as the central tool to investigate the structure of the underlying dynamical system.

• • LUZQUIÑOS SAAVEDRA, DAVID ALONSO (Pontificia Universidad Catolica del Perú, Peru): Gamma/Hadron separation using the arrival time distribution of particle cascades at TeV energies for SWGO

Given the success of high-altitude wide-field gamma-ray detectors, such as HAWC and LHAASO, we explore a new gamma-hadron separation variable for the future Southern Wide-field Gamma-ray Observatory (SWGO), currently in the R&D phase. SWGO will be a ground-based, high duty cycle, extensive air shower water Cherenkov detector array with a high fill factor core, expected to be located in the Atacama Astronomical Park, Chile, at an altitude of 4770 m. To identify gamma ray astrophysical sources, primary particles need to be reconstructed from the air showers reaching the detector array using their characteristics to distinguish between gamma rays, considered as signal, and hadrons (i.e. cosmic rays) that are considered background. We use CORSIKA to simulate the development of air showers in the atmosphere up to the arrival of secondary particles at the array of water Cherenkov tanks. We propose the arrival time distribution of secondary particles reaching the detector array as an alternative gamma/hadron separator variable. To evaluate its performance we simulated photons and protons, as primary particles, in the energy range from 1 to 100 TeV for vertical events (i.e. zenith angle = 0°) reaching the center of the array. The optimal separation parameter found, given the above constraints, is the time of the 15% percentile of arriving particles inside a ring of 100 to 150 m. The recognized signal is ≳ 88% on average and the background rejection is ≳ 79%. Nevertheless, the overall time resolution of the tanks, estimated at 3.2 ns, is comparable to the average time separation between photons and protons, which is above 3.7 ns. Consequently, the actual efficiency of this variable is expected to be lower. Keywords: Particle identification methods, Detector modelling and simulations I, Simulation methods and programs, Gamma detectors.

• Moraes, Gabriel Lambsteim (UNIFEI, Brazil): A solução de Tolman-Oppenheimer-Volkoff (TOV) e suas aplicações

A descrição de sistemas autogravitantes é um pilar da astrofísica. A gravidade Newtoniana descreve com sucesso sistemas de baixa densidade, mas a Relatividade Geral (RG) é essencial para objetos compactos e para o universo em larga escala. Este trabalho compara as abordagens Newtonianas e relativísticas, através da solução de Tolman-Oppenheimer-Volkoff, na modelagem de órbitas em diferentes regimes: desde buracos negros primordiais no interior de estrelas até a dinâmica estelar em galáxias.

POSTERS II (August 13-15) 

• • Magalhães, Larissa Ribeiro (Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo (IAG/USP), Brazil): Numerical simulations of the non-linear DSA process: connecting kinetic scales with astrophysical scales through a modified PIC-MHD approach

The origin of cosmic rays remains one of the central open questions in high-energy astrophysics. It is believed that most galactic cosmic rays (with energies up to ~PeV) are accelerated in non-relativistic shocks produced by the expansion of supernova remnants into the interstellar medium, through the non-linear Diffusive Shock Acceleration (DSA) mechanism, although many details of the process are not yet fully understood. A significant challenge in numerical simulations is the connection between “micro-scale” phenomena, such as instabilities and resonant waves that govern cosmic ray transport, and the “macro-scale” evolution of the supernova remnant shock interacting with the interstellar medium. To better connect these scales in multidimensional magnetohydrodynamic (MHD) simulations that include cosmic rays, we have developed a modified Particle-in-Cell-MHD (PIC-MHD) approach based on the guiding-center approximation for particles. The effects of cosmic ray-induced waves and instabilities are incorporated via a subgrid model. In this research, we compare the evolution of particle acceleration in a two-dimensional shock, using this modified PIC-MHD approach, with fully self-consistent PIC-MHD simulations, where kinetic phenomena are explicitly resolved. This new approach enables the modeling of the particle acceleration process over spatial and temporal scales much larger than the kinetic scales of the particles injected into the acceleration process, providing a method for investigating the non-linear DSA acceleration mechanism.

• • Martinez, Javier Rodrigo (Instituto Argentino de Radiastronomia, Argentina): On the Detectability of Electromagnetic Signatures from Galactic Isolated Black Holes

A vast population of isolated stellar-mass black holes is expected to reside in the Galaxy, yet only one candidate has been confirmed through a microlensing event, and no electromagnetic detection has been reported so far. We investigate the detectability of their putative multi-wavelength emission, assuming accretion from the interstellar medium and the formation of an outflow. Using semi-analytical modelling, we simulate the resulting emission from three key regions: the immediate accretion zone, the outflow-medium interaction structure (thermal and non-thermal), and the non-thermal radiation from relativistic particles diffusing in the environment. Our results indicate that isolated black holes traveling through dense media can produce detectable emission across the spectrum. In particular, accretion related emission could be observed in the mid-infrared and hard X-rays, while the outflow-medium interaction structure may be detectable in the radio and millimetre bands. Gamma-ray detection of diffusing particles is also plausible in dense environments.

• • Martinez Rivero, Rafael Armando (Universidad Industria de Santander, Colombia): Calibration and field deployment of MuTe

MuTe is a portable cosmic-ray muon telescope purpose-built for density-path imaging of Colombia’s Cerro Machín volcano. The detector pairs crossed plastic-scintillator planes with Silicon-Photomultipliers and CAEN FERS front-end electronics. Its geometry, trigger logic, and light collection were first optimised through CORSIKA and GEANT4 simulations, defining the expected angular acceptance and track-reconstruction accuracy. Laboratory commissioning followed: open-sky runs established baseline performance, while lead “staircase” tests confirmed suppression of the soft electromagnetic component. After ruggedisation, the telescope was installed at 2 750 m a.s.l. on Machín’s western flank, where threshold, gain, and alignment calibrations were repeated under field conditions. This poster distils the complete workflow—design, simulation, laboratory calibration, and on-site deployment—showing how a student-built, cost-effective cosmic-ray instrument can be translated from bench to volcano for continuous muographic monitoring

• • Merizalde Aguirre, Daniela Alejandra (USFQ, Ecuador): Adaptations to the Data Analysis Model for Cherenkov Detectors

The Latin American Giant Observatory (LAGO) is an observatory focused on the detection of cosmic rays and space weather phenomena using a network of water Cherenkov detectors. Currently, LAGO is transitioning to new hardware with higher time resolution, which requires an improvement and adaptation of the current calibration algorithms. In this work we present an improvement of such algorithm by focusing in the measurement of the Michel spectrum instead of the caracteristic muon hump (energy deposited by muons crossing vertically the WCD), allowing us to classify the measured signals according to the type of particle crossing the WCD. Thus, we presented the results of a machine learning model based on the OPTICS algorithm to improve particle classification in LAGO’s WCD signals acquired with LAGO’s new hardware.

• • Morales Rojas, Luis Fernando (Pontificia Universidad Católica del Perú, Peru): Machine-Learning Energy Reconstruction for SWGO Using a Multi-Layer Perceptron

The Southern Wide-field Gamma-ray Observatory (SWGO) will deliver unprecedented coverage of the TeV–PeV sky from the Southern Hemisphere. Accurate primary-energy reconstruction is essential for flux and spectral studies, yet classical likelihood fits suffer from large biases at low multiplicities. We present a supervised multi-layer perceptron (MLP) that enhances energy reconstruction for SWGO. Our training sample comprises > 1 × 10⁶ gamma-ray showers generated with CORSIKA, propagated through AERIE, and reconstructed by SWGO-RECO. We select events with ≥ 65 triggered PMT hits, zenith angle θ ≤ 30°, true core radius < 560 m, and primary energies spanning 10¹·⁵–10⁶ GeV. Feature vectors mix hit multiplicities (top/bottom), lateral charge profiles, timing moments, and core geometry. The resulting MLP—implemented in Julia/Lux and optimised for GPU inference—achieves an energy resolution of σ₆₈(log₁₀ E_R / E_MC) ≈ 0.09 at 1 TeV and < 0.07 between 2 TeV and 30 TeV. It outperforms the current likelihood-based LH-LDF fit from ≈ 60 GeV (log₁₀ E ≈ 1.8) up to ≈ 15 TeV (log₁₀ E ≈ 4.2), delivering ≈ 30 % lower resolution across that range (see figure). At higher energies performance remains comparable. We detail the training/validation strategy, feature-importance analysis, and systematic effects from atmospheric depth and detector response. Finally, we outline prospects for integrating the model into SWGO’s real-time analysis chain and for complementing classical methods with quantum-machine-learning techniques under exploration for particle-physics data.

• • Moreno Chalacá, Sebastián (Universidad del Valle, Colombia): Mass-Radius relation for neutron stars in axionic scalar-tensor gravity

Dark matter remains one of the central challenges in theoretical physics and cosmology. In this work, we explore the axion as a candidate for dark matter within a gravitational framework that includes a non-minimal coupling between the axion field and spacetime curvature. We study the impact of this coupling on the structure of realistic neutron stars by solving the modified field equations and obtaining mass-radius relations. These are then compared with predictions from general relativity. Our results reveal some deviations, offering insights into the role of scalar fields in compact astrophysical objects and their possible connection to dark matter.

• • Nascimento, Giovana (Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo, Brazil): Morphological and non-parametric properties of clusters: Abell 1644 and Abell 1631

This project aims to contribute to the understanding of the formation and evolution of the universe through the study of galaxy clusters, the largest gravitationally bound systems in the Universe. A study is conducted on the morphological and nonparametric parameters of galaxies in the Abell 1644 and Abell 1631 clusters. We are specially interested in analysing morphological properties of each cluster, specifically (i) the spatial distribution of disturbed galaxies within the clusters; (ii) the construction of the color–magnitude diagram for the galaxies; (iii) the identification of AGNs (Active Galactic Nuclei) using BPT (Baldwin, Phillips & Terlevich) diagrams; and (iv) the search for images of disturbed galaxies in other bands (e.g., X-rays).

• • Pasquevich, Lucas Manuel (Instituto Argentino de Radioastronomía, Argentina): Astrophysical effects of the Bethe-Heitler mechanism on ultraluminous X-ray sources

Ultraluminous X-ray sources (ULXs) are binary systems in which the observed X-ray luminosity exceeds the Eddington limit. In these systems, the companion star overflows its Roche lobe, feeding matter to the compact object at super-Eddington rates. The radiation pressure inflates the accretion disk in the inner region within the critical radius, where powerful radiation-driven winds are ejected. The wind walls form a low-density conical funnel along the axial direction, where the radiation from the innermost region of the disk is geometrically beamed and reaches the observer. Inside the funnel, the X-ray photon field from the disk interacts with relativistic protons accelerated in shocks producing electron-positron pairs via the Bethe-Heitler mechanism. In this paper, we present a model of the effects of this mechanism within the funnels of ULXs and the subsequent nonthermal MeV emission produced by the secondary pairs as they interact with ambient fields. Our results provide new insights into the high-energy processes occurring in these systems.

• • Passos Reis, Luana (Instituto de Astronomia, Geofísica e Ciências Atmosféricas da USP (IAG-USP), Brazil): Cosmic Ray Acceleration by turbulent-driven magnetic reconnection and the origin of the neutrinos in NGC 1068

The Seyfert Type II galaxy NGC 1068 has been identified as a potential neutrino source by IceCube, with a 4.2 sigma significance detection of a 79(+22-20) neutrino excess from 2011 to 2020 (IceCube Collaboration 2020, 2024). The observed high-energy neutrino flux indicates efficient particle acceleration of hadronic nature along with strong gamma-ray absorption in the source. In this work, we investigate turbulence-driven magnetic reconnection as a mechanism for particle acceleration in the coronal accretion flow surrounding the central black hole. We develop a one-zone model following the framework of de Gouveia Dal Pino & Lazarian (2005) and Kadowaki et al. (2015) to explore how fast magnetic reconnection in the inner coronal disk region accelerates protons and electrons, shaping the spectral energy distribution (SED). Under this scenario, the acceleration sites that inject relativistic protons are significantly smaller than the entire corona. In contrast to recent studies, we find that the acceleration of hadrons is primarily driven by Fermi acceleration within the turbulent reconnection layers, rather than drift acceleration. Our results also indicate that the dominant cooling mechanism for accelerated protons is Bethe-Heitler pair production, driven by interactions with both the disk’s thermal OUV photon field and the coronal X-ray photons.

• • PASTOR CORAL, KARLA MARIA (UNIVERSIDAD NACIONAL DE INGENIERÍA, Peru): Determining the Response of the SWGO Cherenkov Water Detector to the Secondary Cosmic Ray Background

The objective of this work is to develop complex simulations of cosmic ray interaction with the atmosphere (using the CORSIKA simulation package), and with particle detector simulations (performed with GEANT4), we will study the response of the DLWCDs to the cosmic radiation background in the internal material configuration proposed by the collaboration. These particles are continuously entering the detectors and to which our DLWCDs will be constantly exposed. This will allow us to characterize the background noise in the detectors at this altitude level and the detector’s response to individual particles. And also, will help us to calibrate de detector in real time.

• • Peralta Macca, Daniel Felipe (Universidad Nacional de Colombia, Colombia): Minimal Couplings for Dark Matter Production

This is going to be a review of the methods used for the calculation of dark matter relic densities from the scattering of the inflation field to a dark matter candidate using a gravitational mediator. This model’s couplings are minimal, as any other model would also possess them, thus it provides a lower bound for dark matter relic densities and a maximal bound in the reheating temperature. The results here are in the literature, however, novel developments may be done soon since this is an on going research project.

• • Petrosillo, Tamara (Universidad Técnica Federico Santa María, Chile): Simulations for a candidate water Cherenkov detector at SWGO for high-energy EAS

The reconstruction of atmospheric showers from high-energy gamma rays is essential for optimizing the design and performance of the Southern Wide-field Gamma-ray Observatory (SWGO). Several layout options are under consideration for SWGO’s outer array, each involving different detector configurations. This work focuses on simulating the detector response of the M1mT1m tank design, which features two multi-photomultiplier tube (multiPMT) modules. These simulations contribute to the FastSim project, which uses a lookup table (LUT) to capture detector responses from single particles, enabling a much faster alternative to full shower simulations. The results show that the multiPMT configuration captures valuable directional information through distinct patterns in photoelectron counts and timing, improving reconstruction capabilities. Future work will refine fitting procedures and validate the LUT method against full simulations to assess its accuracy and performance benefits.

• • Poiani, Maísa (Instituto de Física – UFU, Brazil): Light Deflection in Stellar Ocultations

Astrometry is an area of Astronomy that aims at precisely measure of the position and movement of celestial bodies in the universe. Within these studies, we highlight events in which a body is temporarily obscured by another, preventing its light from reaching an observer; such an event is called stellar occultation. In particular, there is also the issue of the deflection of light arising from occultations, that results from the deformation that celestial bodies cause in space-time (Klioner, 2003). This causes distortion of observational results and measurements of positions and coordinates. This distortion is even more complex in cases of occultations by natural satellites, where the gravitational effect of the Sun, the planet and the satellite itself contribute to the deflection of light. Faced with these challenges, the present work aims to use physical and mathematical tools, such as the SORA package (Gomes-Júnior, et al 2022), to accurately characterize the astrometric effects of gravitational deviation during stellar occultation. Therefore, we will adopt a methodological approach that combines theoretical analysis and numerical simulations of the gravitational deviation caused by multiple objects simultaneously. References: KLIONER, S. A. A Practical Relativistic Model for Microarcsecond Astrometry in Space. The Astronomical Journal, v. 125, n. 3, p. 1580–1597, 1 mar. 2003. GOMES-JÚNIOR, A. R. et al. SORA: Stellar occultation reduction and analysis. Monthly Notices of the Royal Astronomical Society, v. 511, n. 1, p. 1167–1181, 8 jan. 2022.

• • Rabelo, Eduardo Fonseca (IFSC-USP, Brazil): Mass Composition Classification of Extensive Air Showers at CTAO via Monte Carlo Simulations and Machine Learning

One of the most current problems in the detection of cosmic radiation by the Cherenkov Telescopes is the identification of the primary particle initiated by gammas and electrons. The images generated in the cameras, by both primaries, are very similar, making their identification not a simple task. On the other hand, the images generated by primaries initiated by heavier particles, such as protons, helium and even iron, are different when compared to those of gamma; however, the quality of the generated image and the detection statistic are not accurate enough when using traditional approaches. This work proposes the use of images from these telescopes as input for machine learning to identify these primary particles. Some initial studies showed the need to use images with more pixels for a better identification, so in this work we will only use larger telescopes (more than 20 meters diameter); in the Cherenkov Telescope Array (CTA) these are called LST (Larger Size Telescopes). Preliminary results showed up to 98% of accuracy for gammas identification and up to 94% for electrons, using 4 telescopes in stereo detection. A secondary objective that naturally shows after the first study is to verify if this same methodology could also be capable of associating this learning with macroscopic quantities. Thus, the main contributions for this project are: the ability to classify the particle type and fit the Energy of the shower and to integrate different sources for this purpose.

• • Reis, Christopher Dorvino (USP, Brazil): Argon/xenon-based dark matter detectors and their interactions with neutrino background

The search for dark matter, one of the greatest current astrophysics mysteries, is an increasingly relevant topic as detection technologies and methods advance, in contrast with the lack of conclusive results. Liquid noble gas detectors, more specifically argon and xenon, have proven to be excellent candidates for detecting dark matter. However, with their constantly increasing sensitivity, they are beginning to detect the neutrino background, which can obscure potential dark matter interactions. This results in the need for new detection and data analysis techniques in order to overcome this barrier, known as the “neutrino fog.” In this context, I present the relevant topics, such as the cross section of coherent elastic neutrino-nucleus scattering (CEvNS), the neutrino fog and the neutrino flux at detector sites, the process the detector relies on, and the number of events expected from the neutrino fog in these detectors.

• • Rennó, Mateus Zeferino (UNICAMP, Brazil): Analyses of cosmic-ray arrival directions at the Pierre Auger Observatory: large-scale anisotropies and correlations with starburst galaxies

The origin of the most energetic particles originating from outer space, known as ultra-high-energy cosmic rays, is an open problem in astroparticle physics. We analyze their arrival-direction distributions, looking for an indication of anisotropy. We apply two statistical tests to data obtained by 1600 water-Cherenkov detectors at the Pierre Auger Observatory from 1 January 2004 to 30 April 2017, corresponding to a total exposure of 89,720 km² sr yr by including cosmic rays with energies above 4 EeV (10^18 eV) and local zenith angles up to 80°. Performing a Rayleigh analysis, we find a privileged direction of particles with energies above 8 EeV with a significance level of 5.5 standard deviations (2-sided). This direction is well-modelled by a spherical harmonic expansion truncated to the dipolar order pointing towards 99° +- 10° in right ascension and -22° (with uncertainties of +13° and -12°) in declination with an amplitude of 6.5% (+1.2%, -1.0%). We also investigate the correlation between cosmic rays and starburst galaxies identified in the Fermi-LAT survey by constructing sky maps that account for the exposure of Auger Observatory, attenuation effects due to particle propagation, and the electromagnetic flux of the target sources. We treat the fraction of isotropic background and the angular scale for clustering of particles as free parameters in the sky maps. Running a maximum-likelihood analysis, we find evidence of cross-correlation between cosmic rays with energies exceeding 39 EeV and starburst galaxies at a significance level of 4.1 standard deviations (1-sided).

• • Rizzo, Florencia Nadine (Facultad de Ciencias Astronómicas y Geofísicas – Universidad Nacional de La Plata, Argentina): The PeVatron nature of the super-Eddington microquasar S26

S26 is an extragalactic microquasar with the most powerful jets ever discovered. They have a kinetic luminosity of $L_{\rm j}\sim 5\times 10^{40}\,{\rm erg\, s^{-1}}$. This implies that the accretion power onto the black hole should be super-Eddington, of the order of $L_{\rm acc}\sim L_{\rm j}$. In this work, we model the super-Eddington disk and its wind and develop a jet model to study the particle acceleration and radiative processes occurring in shocks generated near the base of the jet and in its terminal region. Our results show that S26 can accelerate protons to PeV energies in the inner jet and lobes. The ultra-high-energy protons that are accelerated in the lobes of S26 are injected into the interstellar medium and the cocoon that envelops the system. We also present results on the system’s emission and compare them with observational data.

• • Rodrigues, Giovanna (IAG – USP, Brazil): Poissonian Analysis of Gravitational Wave Interferometers

Glitches are non-Gaussian transient noises that impact the ability to identify true gravitational wave signals. This study aims to analyze the statistical behavior of the main types of glitches during an observational run using computational methods, investigating whether their temporal distributions follow a Poisson pattern. This analysis may provide insights into their physical origins, facilitating their mitigation and contributing to the improvement in the quality of gravitational wave detections.

• • Santana Pereira, Guilherme (Instituto de Física de São Carlos, Universidade de São Paulo, Brazil): Study of the Effects of Degradation in Telescopes of Cherenkov Telescope Array Observatory (CTAO)

One of the most urgent problems regarding Cherenkov telescopes is the influence of degradation in image generation. The process to simulate the effects of reflectivity loss in the mirrors and photomultiplyer efficiency loss has been recently implemented on the CTAO simulator, SimTelArray, and will be analysed on this research Using SimTelArray to simulate particle shower detections with degraded mirrors, the effects of said degradation on CTAO will be analysed, providing crucial context in how will the real data be like once the observatory is fully operational.

• • Santos Abreu, Sabrina Brígida (UFRN, Brazil): Challenges in the Detection of Dark Matter: Theoretical and Experimental Perspectives

A brief review of the current challenges in the detection of dark matter, both from theoretical and experimental perspectives. Despite strong indirect evidence for its existence, dark matter has not yet been directly observed. The work discusses the main detection strategies—including direct detection, indirect detection, and collider searches—and explores why these methods have not yet yielded definitive results.

• • Silva, Davi dos Santos (University of São Paulo – USP, Brazil): Building a statistical test for energetic splitting in cosmic ray cascades

The objective of this project is to determine well-defined statistical criteria to quantify, in the form of a statistical hypothesis test, when a given partitioning of a certain amount into several parcels offers significant statistical evidence that a lack of uniformity has occurred in the division process. This problem, apparently of an exclusively mathematical-statistical nature, is actually relevant for characterizing the validity of a simplifying physical hypothesis for the analysis of cosmic ray showers, whereby there would be asymmetry in the division of a particle’s energy between its products in the initial stages. of these cascades.

• • Sousa, Manoel Felipe (Universidade Federal do Paraná, Brazil): Prospects for Gamma-Ray Emission from Magnetar Regions in CTAO Observations

Recent multiwavelength observations have highlighted magnetars as significant sources of cosmic rays, particularly through their gamma-ray emissions. This study examines three magnetar regions—CXOU J171405.7–31031, Swift J1834−0846, and SGR 1806−20—known for emitting detectable electromagnetic signals. We assess the detectability of these regions using the upcoming Cherenkov Telescope Array Observatory (CTAO) by conducting an ON/OFF spectral analysis and compare the expected results with existing observations. Our findings indicate that CTAO will detect gamma-ray emissions from these three magnetar regions with significantly reduced emission flux errors compared to current instruments. In particular, the study shows that the CXOUJ1714−3810 and SwiftJ1834−0846 magnetar regions can be observed by the full southern CTAO arrays in just 5 hr of observation, with mean significances above 10σ and 30σ, respectively. This work discusses the regions analyzed, presents key results, and concludes with insights drawn from the study.

• • Uribe Ramirez, Juan Pablo (Universidad Autonoma de Sinaloa, Mexico): Quantum Algorith Automation for Causal Feynman Loop configurations

Quantum algorithms suppose an advantageous way of finding causal configurations of vacuum Feynman diagrams, given their analogy to querying directed acyclic graphs (DAGs) in graph theory. In this work we explore the automation of quantum algorithms using graph theory techniques, in particular Minimum Clique Cover problem, using only multicontrolled Toffoli gates and XNOT gates.

• • Valiati, Marcus (Brazilian Center for Physics Research (CBPF), Brazil): Simulation-Based Inference in SED modeling of AGNs

Active Galactic Nuclei (AGNs) host a supermassive black hole at the center of a galaxy, surrounded by a torus of gas and dust, as well as a relativistic jet. According to the AGN unification model, these objects are classified based on the observer’s viewing angle of the jet, encompassing radio galaxies, quasars, and blazars. Blazars are characterized by jets that are closely aligned with the observer’s line of sight. Their emission spans the entire electromagnetic spectrum, from radio to very high energy γ rays. The spectral energy distribution (SED) of blazars typically displays a double-humped structure. The first peak, from infrared to X-rays, is attributed to synchrotron radiation from a population of electrons within the jet’s magnetic field. The second peak, located in the γ-ray band, is explained by leptonic or hadronic models. The leptonic scenario, synchrotron photons are upscattered via the inverse Compton process (SSC), while hadronic models involve synchrotron emission from protons or photo-meson interactions. To model the full SED, several numerical tools like JetSet, agnpy, ATHEνA, and SOPRANO are used but they often demand substantial computational resources. Simulation-Based Inference (SBI) emerges as a promising alternative, offering a likelihood-free Bayesian framework to infer physical parameters by training neural networks on simulated data. In this project, we generated a synthetic set of SSC parameters using Latin Hypercube Sampling, which served as input to a CNN trained to emulate SSC emission. The output SEDs were then used to train the SBI model. We applied a neural spline flow (NSF) density estimator to infer SSC parameters directly from the SED. Our method was tested on both clean and noise-perturbed datasets, to better approximate real observational conditions. The goal is to recover the SSC parameters that best reproduce observed SEDs, offering a fast and efficient alternative for parameter estimation in multiwavelength modeling of blazars.

• • Ventura, Pedro Zilves Maio (IF – USP, Brazil): Searching for Light Dark Matter in Noble Gases and Semiconductors

The search for light dark matter, with masses below the GeV scale, has gained prominence in recent years. In this context, both nuclear and electronic scattering processes become relevant, depending on the interaction model considered. In this study, we investigate theoretical expectations for the interaction of light dark matter particles with various target materials, with particular emphasis on liquefied noble gases and semiconductors. We analyze the ionization form factors and kinematic thresholds associated with each material, and evaluate their respective sensitivities to different classes of dark matter models. This analysis aims to identify the potential advantages offered by each detection medium in probing the sub-GeV dark matter parameter space.

• • Zamperlini dos Santos, Joao Victor (Federal University of Santa Catarina, Brazil): Spacetime curvature corrections for the Yukawa potential and its application for the Reissner-Nordström Metric

In this work we investigate the influence of the spacetime curvature on the Yukawa potential, focusing on boson-boson interactions derived from the ϕ³ theory. Using the Bunch-Parker propagator expansion within Born’s first approximation, we derive a Yukawa-like potential in a curved spacetime. We analyze the impact of the curvature on the propagator in momentum space, revealing modifications to the potential and showing that the corrections are determined by geometric quantities from Einstein’s equations, like the Ricci scalar and tensor. We illustrate this using the Reissner-Nordström metric, highlighting the corrections’ magnitude for specific parameters. Our results underscore the nuanced interplay between spacetime curvature and quantum interactions, providing insights into nucleon-nucleon systems in curved spacetimes or near strong gravitational fields.

• • Zegarra, Danilo (Pontificia Universidad Católica del Perú, Peru): Displaced (dark)photons from low reheating temperature scenarios

We study an effective extension of the Standard Model that includes a U(1)’ gauge symmetry and a pseudoscalar field. The model predicts a dark vector boson as a dark matter candidate and a heavier pseudoscalar that can behave as a long-lived particle at collider scales. The dark sector couples to the Standard Model through a dimension-5 operator, allowing the decay of the pseudoscalar into a dark photon and a visible photon, and through a Higgs portal interaction enabling Higgs decays into pseudoscalars. In this poster, we focus on the collider phenomenology of the long-lived pseudoscalar. We simulate the model using MadGraph5_aMC@NLO, perform detector-level analysis with Delphes, and apply event selections targeting displaced photon signatures. As a final result, we present contour plots in the plane of the pseudoscalar mass and the dark sector coupling g_D, with the z-axis showing either the maximal branching ratio of the Higgs decay into pseudoscalars or the effective coupling strength required to produce visible signals. This work is part of an international collaboration between the Pontificia Universidad Católica del Perú (PUCP), Universidad San Sebastián (Chile), and Universidad de la República (Uruguay).

• • Espinosa, Luna Costa Lacerda (Universidade de São Paulo, Brazil): Stellar Bubbles as Particle Accelerators: A Case Study of G2.4+1.4

Strong stellar winds from massive, early-type stars have been suggested as capable of accelerating particles to very high energies. Intense shock waves are formed as the wind propagates and interacts with the interstellar medium, shaping the surrounding region into a stellar bubble. In some cases, part of the kinetic power of the shock contributes to the creation of relativistic particles. In 2019, Prajapati et al. reported the first detection of nonthermal radio emission from the stellar bubble G2.4+1.4, associated with an oxygen-rich Wolf-Rayet star. The observed emission is consistent with synchrotron radiation from relativistic electrons. Assuming the particles are locally accelerated at the termination shock, we have developed a detailed spatially extended model to estimate the nonthermal emission produced by both electrons and protons. Under very general assumptions, maximum energies were found to be in the TeV range for electrons, and up to a few hundred TeV for protons. In order to account for the observations, a high magnetic field (ca. 250 μG) is required. We obtained emissivity maps at both radio (thermal and nonthermal) and gamma-ray energies. Our results support the idea that the winds of massive stars are efficient particle accelerators.

• Masotti, Jaqueline De Fatima (IAG – USP, Brazil): PeVatron source LHAASO J1908+0621: a mixed scenario for gamma-ray emission?

The study of Galactic cosmic rays currently relies on the observation and modelling of gamma-ray emission from molecular clouds. In order to find sources at energies ~100 TeV, it is required to find sources known as PeVatrons, capable of accelerating the cosmic rays up to 1 PeV. Usually, the association between molecular clouds and supernova remnants are the favourite candidates as PeVatron sources. Unfortunately, due to source contamination and the angular resolution limitation of the current observatories, it is difficult to identify the exact accelerating source in many of the reported PeVatrons. A particularly notable case is LHAASO source J1908+0621 (MGRO J1908+06), as it was detected by several gamma-ray facilities and is associated with the SNR G40.5-0.5 in interaction with a MC and is also associated with two pulsars, PSR J1907+0602 and PSR J1907+0631. In this work, we aim to develop a model capable of distinguishing which accelerator is responsible for the detected emission or if it is a combination of both pulsar and SNR. Firstly, we calculated the high-energy emission produced in the interaction of SNR G40.5-0.5 with the ambiente medium using a time-dependent diffusion model. We fitted the observed very-high emission in the range 10 − 100 TeV by assuming a total energy in protons of ~10$^{49}$ erg. As the source region also has another possible accelerator, we also considered the feasibility of the leptonic contribution from the pulsar PSR J1907+0602 in the detected emission as it would add a component to our pure hadronic model that could explain the lower energies. We conclude that the diffusion of the protons in the cloud should be slow.

Announcement:

Application deadline: June 6, 2025 (closed)

 The schedule might be changed.

• 09:00 - Felix Aharonian (DIAS, Ireland): Overview of Ground-based Gamma-ray Astronomy
• 11:00 - Elisabetta Bissaldi (INFN and University of Bari, Italy): Lecture 1 – High-energy GRBs: Lessons learned from the Fermi mission and TeV observations
• 14:00 - Elisabetta Bissaldi (INFN and University of Bari, Italy): Lecture 2 – The Gamma-ray role in multi-messenger observations of gravitational waves: From Fermi to ground-based observations
• 16:00 - Michele Doro (INFN and University of Padova, Italy): Lecture 1 – Introduction to Cherenkov Telescopes

• 09:00 - Michele Doro (INFN and University of Padova, Italy): Lecture 2 – Fundamental Physics with Gamma-rays I: Dark Matter
• 11:00 - Michele Doro (INFN and University of Padova, Italy): Lecture 3 – Fundamental Physics with Gamma-rays II: Other Topics
• 14:00 - Markus Boettcher (NWU, South Africa): Lecture 1 – Active Galactic Nuclei with Gamma-rays
• 16:00 - Markus Boettcher (NWU, South Africa): Lecture 2 – Active Galactic Nuclei and Multi-messenger neutrinos

• 09:00 - Rafael Alves-Batista (IAP, France): Lecture 1 – Introduction to HECRs: phenomenology, observations, and open questions
• 11:00 - Rafael Alves-Batista (IAP, France): Lecture 2 – Cosmic-ray acceleration and sources
• 14:00 - Ulisses Barres de Almeida (CBPF): The Southern Wide-field Gamma-ray Observatory: A Next-generation Ground-based Survey Instrument for Gamma-ray Astronomy
  • Abstract
• 16:00 - Raniere de Menezes (CBPF, Brazil): Session 1 – Stereoscopic analysis of the Crab Nebula with Imaging atmospheric Cherenkov telescopes

• 09:00 - Rafael Alves-Batista (IAP, France): Lecture 3 – Extragalactic propagation of cosmic-rays
• 11:00 - Shoushan Zhang (IHEP, China): Introduction to Extensive Air-Shower Arrays and LHAASO
• 14:00 - Gustavo Romero (IAR, Argentina): Lecture 1 – Very-High Energy Galactic Sources I
• 16:00 - Raniere de Menezes (CBPF, Brazil): Session 2 – The Galactic center above 1 TeV: simulations with the SWGO science tools

• 09:00 - Rafael Alves-Batista (IAP, France): Lecture 4 – Galactic propagation of cosmic rays
• 11:00 - Gustavo Romero (IAR, Argentina): Lecture 2 – Very-High energy Galactic Sources II
• 14:00 - Gustavo Romero (IAR, Argentina): Lecture 3 – Galactic PeVatrons
• 16:00 - Raniere de Menezes (CBPF, Brazil): Session 3 – Analysis of a BL Lac object over 5 decades of energy with Fermi-LAT, CTA and SWGO

Venue: The event will be held at IFT-UNESP, located at R. Jornalista Aloysio Biondi, 120 – Barra Funda, São Paulo. The easiest way to reach us is by subway or bus, See arrival instructions here.

Accommodation: Participants whose accommodation will be provided by the institute will stay at Hotel Intercity the Universe Paulista. Hotel recommendations are available here.

Attention! Some participants in ICTP-SAIFR activities have received email from fake travel agencies asking for credit card information. All communication with participants will be made by ICTP-SAIFR staff using an e-mail “@ictp-saifr.org”. We will not send any mailings about accommodation that require a credit card number or any sort of deposit. Also, if you are staying at Hotel Intercity the Universe Paulista, please confirm with the Uber/Taxi driver that the hotel is located at Rua Pamplona 83 in Bela Vista (and not in Jardim Etelvina).

BOARDING PASS: All participants, whose travel has been provided or will be reimbursed by ICTP-SAIFR, should bring the boarding pass  upon registration. The return boarding pass (PDF, if online check-in, scan or picture, if physical) should be sent to secretary@ictp-saifr.org by e-mail.

Visa information: Nationals from several countries in Latin America and Europe are exempt from tourist visa. Nationals from Australia, Canada and USA are required to apply for a tourist visa.

Poster presentation: Participants who are presenting a poster MUST BRING A PRINTED BANNER . The banner size should be at most 1 m (width) x 1,5 m (length). We do not accept A4 or A3 paper.

Power outlets: The standard power outlet in Brazil is type N (two round pins + grounding pin). Some European devices are compatible with the Brazilian power outlets. US devices will require an adapter.