Heritage, Indigenous Peoples and Astronomy

• Javier Mejuto (Universidad Nacional Autónoma de Honduras)

The use and appropriation of common spaces, public spaces, and indigenous lands have become frequent and normalized, unfortunately this is also true for Astronomy, Astrophysics and Space Sciences. In this work, the indigenous concerns and social movements regarding sacred lands and astronomical facilities that have been built upon them will be presented. The joint initiative IAU/RAS/AAS Working Group on Culturally Sensitive Sites will also be presented along with its main objectives, and first activities. The first efforts will be two-fold: first, to make astronomers better aware of such sensitivities and how they may best be addressed, and next how much empathy can better bond science and culture. The aim of this work is to open astronomical science to broader perspectives, the role of native societies in preserving humanity’s astronomical heritage, and indeed how astronomy can play a decisive role as an open discipline in the development of science and inclusivity worldwide. Research, education and outreach in Astronomy and Astrophysics must play a role in that. We all live under one sky.

The Archaeoastronomy of Tikal, Guatemala: A Reanalysis

• Steven Gullberg (University of Oklahoma)

The great Maya city of Tikal was a major center of political, economic, and religious influence from its earliest pre-classic foundations to its classic period heights-- through its fall and reestablishment, until its eventual abandonment. Like many other polities of the ancient Maya, Tikal’s city-planning and architectural organization was designed to incorporate the beliefs and principles of the Maya cosmos. It’s earliest ceremonial plaza, the Mundo Perdido, is one of the oldest pre-Classic E-Groups of the Petén; the astronomy of E-Groups is a topic which has been debated by archaeologists and archaeoastronomers alike over the past century. New measurements of Mundo Perdido will be analyzed within the framework of recent E-Group theories posited by Ivan Ŝprajc (2021). In 1988 Aveni and Hartung discussed the archaeoastronomy and dynastic history at Tikal. Breakthroughs in the decipherment of the Maya glyphs over the intervening decades has greatly increased our understanding of Tikal’s dynastic history while interpretations in the field of archaeoastronomy have become more rigorous. In this light, the resurvey and reanalysis of several Tikal’s great temples is warranted. Lastly, it will be demonstrated that the unique twin-pyramid complexes of Tikal not only exemplify many of Ashmore’s (1991) principal components of the Classic Maya cosmological template, but also present grand three-dimensional models of the Sun’s movement through the cosmos-- constructed in celebration of calendrical period endings.

Can Quantum Mechanics explain the Dark Universe?

• Tonatiuh Matos

Two of the most impressive open questions in science are, without a doubt, the discovery of the nature of Dark Matter and Dark Energy, the so-called Dark Universe. Scientists have worked to solve these questions for many years, decades. Quantum Mechanics (QM) was established to understand the microworld, atoms, molecules, etc. Since 1998 we have carried out a systematic study of the Scalar Field Dark Matter model, also called Ultralight Dark Matter model where Dark Matter satisfies the Schrödinger-Poisson equations. In this talk we are going to speak about how QM can give an alternative explanation to the problem of the Dark Universe, assuming that Dark Matter halos behave like atoms and dark energy could be a consequence of the most elemental precepts of QM.

Search for dark photons in heavy-ion collisions

• Elena Bratkovskaya

The vector $U$-bosons, or so called 'dark photons', are one of the possible candidates for the dark matter (DM) mediators. They are supposed to interact with the standard matter via a 'vector portal' due to the $U(1)-U(1)^\prime$ symmetry group mixing which might make them visible in particle and heavy-ion experiments. While there is no confirmed observation of dark photons, the detailed analysis of different experimental data allows to estimate the upper limit for the kinetic mixing parameter $\epsilon^2$ depending on the mass $M_U$ of $U$-bosons which is also unknown. In Ref. [1] we have introduced a procedure to define theoretical constraints on the upper limit of $\epsilon^2(M_U)$ from heavy-ion (as well as $p+p$ and $p+A$) dilepton data. Our analysis is based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach which reproduces well the measured dilepton spectra in $p+p$, $p+A$ and $A+A$ collisions. Additionally to the different dilepton channels originating from interactions and decays of ordinary (Standard Model) matter particles (mesons and baryons), we incorporate in the microscopic transport approach - for the first time - the decay of hypothetical $U$-bosons to dileptons, $U\to e^+e^-$, where the $U$-bosons themselves are produced by the Dalitz decay of pions $\pi^0\to \gamma U$, $\eta$-mesons $\eta \to \gamma U$ and Delta resonances $\Delta \to N U$. Using the fact that dark photons are not observed in dilepton experiments so far one can require that their contribution can not exceed some limit which would make them visible in experimental data. By varying the parameter $\epsilon^2(M_U)$ in the model calculations, one can obtain upper constraints on $\epsilon^2(M_U)$ based on pure theoretical results for dilepton spectra under the constraint that the 'surplus' of the DM contribution doesn't overshine the SM contributions (which is equivalent to the measured dilepton spectra) with any requested accuracy. We confront our results with the analysis from the HADES Collaboration [1] at SIS18 energies where the dark photons are not observed as well as with the world data collection. This analysis can help to estimate the requested accuracy for future experimental searches of 'light' dark photons by dilepton experiments. We note that this procedure can be extended for the search of dark photons of any masses when the corresponding production and decay channels are implemented in the transport approach. [1] I. Schmidt, E. Bratkovskaya, M. Gumberidze and R. Holzmann, Phys. Rev. D 104, no.1, 015008 (2021) [arXiv:2105.00569 [hep-ph]]. [2] G. Agakishiev et al. [HADES], Phys. Lett. B 731, 265-271 (2014) doi:10.1016/j.physletb.2014.02.035 [arXiv:1311.0216 [hep-ex]].

The role of a standard family of Supernovae in the creation of the BdHNI , BDHNII and BDHNIII Grbs

• Remo Ruffini (ICRANet)

In this contribution we present the most recent results about the role of a standard family of Supernovae in the creation of the BdHNI , BDHNII and BDHNIII Grbs. Some important conclusions and open questions are addressed.

Where we are with the Dark Energy Spectroscopic Instrument ?

• Mariana Vargas Magana

The Dark Energy Spectroscopic Instrument is a fourth generation dark energy experiment which will revolutionate the cosmological constraints that we can extract from the large scale structure of the universe. DESI started to take data in 2020, and now it just finished the September this first year of data. In this talk, I will summarize the survey, present the status of the experiment and give some highlights of the analysis being performed right now with the data collected, the simulations and the preparation of the analysis.

A (axial)vector meson extended quark-meson model to describe quark matter in the core of neutron star

• György Wolf (Wigner RCP)

The existence of quark matter inside the cores of heavy neutron stars is a possibility which can be probed with modern astrophysical observations. We use an (axial)vector meson extended quark-meson model to describe quark matter in the core of neutron stars. We discover that an additional parameter constraint is necessary in the quark model to ensure chiral restoration at high densities. Since they significantly increase the radii of hybrid stars, large sigma meson masses are excluded – consistently with our purely particle physics-based parametrization. The vector coupling can be constrained by mass limits since the maximum mass of hybrid stars is only weakly dependent on the phase transition. We performed a full Bayesian analysis using multiple astrophysical constraints: GW170817, NICER measurements and mass constraints. The results for the quark model parameters are consistent with our simple M–R relation-based investigation, but in addition, we found that observations are best accommodated by a stiff intermediate region with a center at ~4 n0.

Neutron star collisions and the gravitational collapse

• Matthias Hanauske

With the first detection of gravitational waves from a binary system of neutron stars GW170817, a new window was opened to study the properties of relativistic fluids at and above the nuclear-saturation density. Reaching densities a few times that of nuclear matter and temperatures up to 100 MeV, such mergers also represent potential sites for a phase transition from confined hadronic matter to deconfined quark matter. A hypermassive hybrid star is a metastable remnant of a binary neutron star merger, and in contrast to its purely hadronic counterpart (hypermassive neutron star), it contains deconfined strange quark matter in its inner region. During the last phase, the hypermassive hybrid star collapses into a black hole and the quark matter in the inner region gets macroscopically confined by the formation of the event horizons of the resulting rotating black hole.

Quark Deconfinement in Neutron Stars and Their Mergers

• David Blaschke

We outline the role that an early deconfinement phase transition from normal nuclear matter to a color superconducting quark-gluon plasma phase plays for the phenomenology of supernova explosions and binary neutron star mergers. To this end we develop a density functional approach to the equation of state (EoS) of quark matter with confinement and color superconductivity [1] and construct the transition to the EoS of the hadronic matter phase from vanishing to moderately high temperatures that will become accessible also in future terrestrial experiments with heavy-ion collisions. For the first time a phase transition construction is developed that allows for multiple critical points in the QCD phase diagram, including the possibility of a “crossover all over” [2]. We study the connection of such hybrid EoS with the mass-radius relation of cold compact stars, including the intriguing possibility of additional families, as a consequence of the presence of an early and strong phase transition. Special emphasis is devoted to the simultaneous fulfillment of the new constraint from the NICER mass and radius measurement on PSR J0740+6620 and the tidal deformability constraint from the binary neutron star merger event GW170817 which require the EoS to be soft at about twice saturation density and to stiffen at higher densities. Such a pattern is provided by an early and strong deconfinement transition [1]. We discuss whether the deconfinement signals remain intact which have recently been found in dynamical astrophysical scenarios, such as binary compact star mergers including the subsequent emission of gravitational waves [3] and supernova explosions of massive supergiant stars where neutrinos and gravitational waves play the role of messengers [4,5]. References: [1] O. Ivanytskyi and D. Blaschke, “Density functional approach to quark matter with confinement and color superconductivity”, Phys. Rev. D 105 (2022) 114042; arXiv:2204.03611. [2] O. Ivanytskyi and D. Blaschke, “A new class of hybrid EoS with multiple critical endpoints for simulations of supernovae, neutron stars and their mergers”; arXiv:2205.03455. [3] A. Bauswein et al., “Equation of state constraints from the threshold binary mass for prompt collapse of supernova mergers” Phys. Rev. Lett. 125 (2020) 141103. [4] T. Fischer et al., “Quark deconfinement as supernova explosion engine for massive blue supergiant stars”, Nature Astron. 2 (2018) 980. [5] A. Bauswein, D. Blaschke and T. Fischer, “Effects of a strong phase transition on supernova explosions, compact stars and their mergers”; arXiv:2203.17188.

The cosmological constant in Loop Quantum Cosmology revisited

• Omar Gallegos (Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN)

The current acceleration of our Universe leads to the question of a possible origin of a cosmological constant. Within loop quantum cosmology a recent proposal yields an effective model including a behavior corresponding to it which origin lies in the relative weight of two pieces entering the Hamiltonian constraint, Euclidian and Lorentzian. Matching with the observations essentially fixes such relative weight. However, this analysis does not take into account the selfadjoint character of the Hamiltonian constraint. In this work, we take a first step in this direction. Previous, selfadjointness results developed for the purely Euclidian term are here extended to incorporate it with the Lorentzian one. The ensuing effective dynamics is studied together with its possible consistency with observations.

Effect of the Metallicity of the Intergalactic Medium in the Lyman-α Forest Correlation Function

• Andrea Muñoz-Gutiérrez

The Lyman-α (Lyα) forest allows to constraint cosmological parameters at z>1.8 using the technique of standard rulers determined by Baryon Acoustic Oscillations (BAO). This makes it an important tracer for the study of the Universe at high redshift. For this work several synthetic datasets have been generated to understand the astrophysical effects and contaminants that contribute to the shape of the Lyα flux correlation function ξLyα, and to be able to reproduce the correlation function measured with data spectra from different galaxy surveys (eBOSS and DESI). Among these phenomena the presence of metals in the Intergalactic Medium (IGM) translate into an important bias in the ξLyα with respect to the ξLyα calculated considering an only Hydrogen in the IGM. In this work we study the influence of the metallicity in ξLyα, simulating the presence of four Si transitions in synthetic spectra developed in preparation for DESI and compared with the data obtained in the DR14 of eBOSS. These results were used for the analysis of eBOSS DR16 and are currently being used for the analysis of the first data release of DESI.

The curvature energy-momentum tensor in extended theories of gravity with curvature-matter couplings

• Sergio Mendoza (Instituto de Astronomia, Universidad Nacional Autonoma de Mexico)

It is shown how in general terms one can construct a curvature energy-momentum tensor in extended theories of gravity with particular attention to gravitational theories with curvature-matter couplings for ideal fluids. In passing by, it will also be shown a unique way to define the matter Lagrangian for the case of ideal fluids.

Constraints in the TeV halo population of M31

• Alexis Andrés (IA-UNAM)

TeV halos are a new class of extended gamma-ray objects recently discovered around middle-aged pulsars. Although it is still unclear if TeV halos are characteristics of all pulsars, their population in the Milky Way galaxy has been studied. In this work, we study the TeV halo population in the Andromeda galaxy (M31), the closest largest spiral galaxy to the Milky Way. Concretely, we assume M31 is a Milky Way-like galaxy and compute the contribution of TeV halos to the gamma-ray emission of M31. We acknowledge the support from PAPIIT IG101320.

Mildly relativistic cokscrew jets as rotated spirals

• Alejandro Raga

It has been noted before that the observed spiral structure of free-streaming, precessing jets appears to be increasingly "rotated" (i.e., with an apparent increase/decrease of the angle between the precession axis and the plane of the sky) as v/c increases. We derive the value of the rotation angle, and show that this "rotated spiral" description is appropriate for jets with v/c<0.8. We find that in order to obtain the correct predicted image, the half-opening angle of the spiral also has to be modified as a function of v/c.

A reconstruction scheme for f(T) gravity and information theory based model validation

• Sanghati Saha (Amity University Kolkata)

Here, We will be reporting a study on Generalized Chaplygin Gas(GCG) in bulk viscosity framework. We have reconstructed f(T) gravity considering that the background fluid, is evolving as GCG interacting with pressureless dark matter in a viscous scenario. Stability of reconstructed f(T) has been analyzed against small purterbations. The model has been finally validated against observational data through Shannon entropy maximization and Gaussian Mixture Model.

New tools for better characterizing astroparticle physics sites and detectors for the Latin American Giant Observatory

• Hernán Asorey

The Latin American Giant Observatory (LAGO) is an extended astroparticle observatory, consisting of a synchronised network of water Cherenkov detectors operating in Latin America and covering a wide range of altitudes above sea level and geomagnetic rigidity cut-offs[1]. LAGO is operated by the LAGO Collaboration, a highly collaborative organization with 100 members from more than 30 Iberoamerican institutions. LAGO research objectives are focused on studying of high-energy astrophysical and space weather and climate phenomena, by indirectly measuring the temporal evolution of the flux of galactic cosmic rays from ground level[2]. The interaction of such cosmic rays with the atmosphere produces a large number of secondary particles via radiative and decay processes. These true cascades of particles, collectively known as Extensive Air Showers, could reach up to $10^{11}$ particles at the instant of their maximum development. To accomplish these tasks we have developed several computational tools[3]; that take advantage of the increasing computational capabilities available at high-performance computing facilities and in cloud-based computing environments, such as the European Open Scientific Cloud (EOSC)[4]. With these tools, we can calculate the expected particle flux at any place in the World, including real-time atmospheric and geomagnetic effects, reproducing the expected signals in different types of detectors. We can also calculate the impact in the expected flux due to the occurrence of transient astrophysical phenomena, such as those related to Solar Activity[5] or the high energy component of Gamma-Ray Bursts[6]. In this contribution, we will show how this very complex sequence of simulations is helping us to characterize new sites for our Observatory and to design new and improved astroparticle detectors for the LAGO detection network.

Air Showers Simulations to Produce Technological Results

• Rafael Mayo-García (CIEMAT)

Atmospheric radiation is mainly produced during the interaction of high energy cosmic rays with the atmosphere. After the first interaction of these primary cosmic rays, a series of radiative and decay processes generate a collective process known as Extensive Air Shower (EAS), with up to 10 secondary particles per primary per GeV at the altitude of the maximum development, and continue evolving up to reach the ground level. Bearing this in mind, calculating the atmospheric radiation background is a very complex and demanding task. This computation is originated from the integration of all the secondary particles produced by the complete and modulated flux of cosmic rays that impinge on the atmosphere. For doing this we developed ARTI [1], a computational framework that takes advantage of the state-of-the-art radiation propagation and interaction codes, such as CORSIKA [2] and Geant4 [3], to trustworthily estimate the expected flux of radiation at any place in the World under real-time evolving atmospheric and geomagnetic conditions [4]. We are also capable to include the impacts produced during the sudden occurrence of transient astrophysical phenomena. As these calculations require a vast amount of computational resources, several approaches were adopted, such as the recent development of OneDataSim [5], a virtualized application to run ARTI on high-performance computing and cloud-based environments. In this work, we show some of the implications and technological applications of our research, including results related to the precise calculation of the expected muon flux at underground laboratories, the mining prospecting and volcanoes risk assessment in muography, some new applications for precision agriculture and personal safe ward, and even how we are able to predict the occurrence of silent and non-silent errors at the new exascale supercomputers centres. In addition, some results will be shown for the future ANDES underground laboratory. Thus, regarding the study of high energetic secondary particles at the tens of TeV scale for this lab background calculations and the expected flux of muons for muography geophysical applications, the expected flux over an integration time of 1 year at different altitudes of the ANDES mountain profile will be presented. In all those cases, the accuracy and statistical significance of previous results have been extended by using these new resources. References [1] C. Sarmiento-Cano et al., arXiv:2010.14591 [astro-ph.IM] (2021). [2] D. Heck et al., Forschungszentrum Karlsruhe Report FZKA 6019 (1998) [3] S. Agostinelli et al., Nucl. Instrum. Meth. A 506 250-303 (2003) [4] H. Asorey, L.A. Nuñez, M. Suárez-Durán. Space Weather 16, 461-475 (2018) [5] A.J. Rubio-Montero et al. In 2021 Winter Simulation Conference Conf. Proc, 1-12 (2021) Acknowledgments This work has been partially funded by the Spanish Ministry of Science, Innovation, and Universities CODEC-OSE project (RTI2018-096006-B-I00) and the Comunidad de Madrid CABAHLA project (S2018/TCS-4423), both with European Regional Development Fund (ERDF). It also profited from funding received by the H2020 co-funded project European Open Science Cloud - Expanding Capacities by building Capabilities (EOSC-SYNERGY, No. 857647). Simulations carried out made also use of the computing facilities provided by CETA-CIEMAT and CIEMAT.

Review of Latest Advances on Dark Matter

• Eugene Oks (Auburn University)

The review will cover the latest advances in understanding dark matter. At the beginning it will follow my review on dark matter published in 2021 in the Elsevier journal “New Astronomy Reviews” (v. 93, 101632) and my review published in 2021 by Nova Science Publishers as a chapter in the book “Advances in Dark Matter Research”. Then the current review will cover the newest results published after the above two reviews had been printed.

On the maximum mass of differentially rotating neutron stars and strange quark stars

• Dorota Rosinska

An understanding of differentially rotating relativistic stars is key to many areas of astrophysics, in particular to the emission of gravitational waves. A newly born, proto-neutron star or a compact remnant of neutron stars binary merger are expected to rotate differentially and to be important sources of gravitational radiation. A highly accurate and stable, relativistic, multidomain spectral code is used to explore the whole solution space for broad ranges of the degree of differential rotation. Staying within an astrophysically motivated range of rotation profiles, we investigate the characteristics of neutron stars with maximal mass for all types of families of differentially rotating neutron stars and different equations of state. We find various types of configurations, which were not considered in previous work, mainly due to numerical limitations. The maximum allowed mass for the new types of configurations and moderate degree of differential rotation can be even 2-4 times higher then the maximum mass of non-rotating neutron stars with the same equation of state. Differential rotation can temporarily stabilize a hyper-massive neutron star against gravitational collapse. This result may have important consequences for the gravitational wave signal expected from coalescing neutron star binaries or from some supernova events.

Constraints on the EoS of strongly interacting matter and on particle properties from relativistic heavy ion collisions

• Joerg Aichelin (SUBATECH)

The calculation of neutron star properties as well as the interpretation of the gravitational wave results for neutron star collisions requires the knowledge of the equation of state of strongly interacting matter. Relativistic heavy ion collisions have collected over the last years a number of results which are sensitive on the nuclear equation of state and the properties of elementary particles if they are brought in a strongly interaction environment. State of the art transport theories like PHSD or PHQMD have been used to extract this equation of state information contained in the experimental results. We report on what we know presently about the equation of state up to densities of about 3 times normal baryon densities and temperatures up to around 100 MeV.

Strange stars confronting with the observations: non-Newtonian gravity effects, or existence of a dark-matter core inside the stars

• Shu-Hua Yang (Central China Normal University, Wuhuan, China)

We find that the existence of strange stars is ruled out by the dimensionless tidal deformability of a 1.4 M_sun star of GW170817 and the mass of PSR J0740+6620 , both for the standard MIT bag model and for the density dependent quark mass model. However, if non-Newtonian gravity effects are considered, strange stars can exist for certain ranges of the values of the non-Newtonian gravity parameter. An alternative explanation to the observations is to suppose that strange stars in GW170817 have a dark-matter core.

Dark Matter Searches Through Multi-Messenger Observations of Compact Stars

• David Edwin Alvarez Castillo (Institute of Nuclear Physics PAS)

The purpose of this talk is discuss the possibility of detection of dark matter through multiple observations of compact stars and related phenomena. Recent scientific and technological developments have allowed for a better study of the nature of these astrophysical objects, in particular of the equation of state (EoS). As we advance on the quest for clarification of the neutron star internal content, we will be able to reveal or discard the existence of dark matter in the corresponding stellar environments. In one hand, new channels of multi-messenger observations like gravitational radiation from merger events of binary systems of compact stars or radio and X-ray signals from isolated pulsars have revealed their most basic structural properties like mass, radius, compactness, cooling rates and compressibility of their matter. In the other hand, nuclear measurement and experiments have narrowed the EoS uncertainty in the lowest to intermediate density range. Importantly, there exist several types of violent, transient energetic emissions associated not only with the strong magnetic fields and extreme gravity in the proximity of these objects but with explosive, evolutionary stages often triggered by mass accretion from companion stars. Therefore, we expect that the presence of dark matter will leave an imprint in the many kinds of detected signals from compact stars.

Coherent quantum states in resonant-mass gravitational wave detectors

• Carlos Frajuca (IFSP)

Quantum coherent states is a new features in quantum mechanics. Resonant-mass gravitational waves detectors didn´t succeed in detecting gravitational waves probably because of the operational frequency range chosen when the design of such detectors. But such detectors can be important in the future. This work describe the importance of quantum coherent states when the a resonant-mass gravitational detects a energy from the gravitational wave very very close to the quantum limit. At this point quantum coherent states of vibration and quantum non-demolition measurements becomes essential.

Simulating the Early Universe

• David Garrison (University of Houston-Clear Lake)

The Numerical Cosmology Group at UHCL has been working for several years to develop the most accurate simulations of the Early Universe possible in order to answer several basic questions such as when did the first magnetic fields develop? In addition, our numerical code can be used to test several fundamental theories in physics. In this presentation, I plan to talk about how we developed this simulation software and what we have already learned from using it. The primary focus of this talk will be Magnetogenesis or the creation of the first magnetic fields in the universe.

Deflection of ultrarelativistic massive particles in Schwarzschild space-time

• Milton Jair Santibáñez Armenta

Gravitational fields curve space-time about them, modifying massive and non-massive particle trayectories. In this work the delfection angle we study the deflection angle generated by the change in the trayecoties affected by the gravitational field of a Schwarzschild space-time. We present an exact analytic formula for small angles and a useful relation for numerical computations. Different applications, in particular to ultrarelativistic neutrinos are presented.

Expected exclusion limits to TeV dark matter from the Perseus Cluster with CTA

• Sergio Hernández-Cadena

Clusters of galaxies are the largest gravitationally-bound structures in the Universe. They are composed of galaxies and gas (~15% of the total mass), and dark matter (DM; ~85%). If the DM is composed of Weakly Interacting Massive Particles (WIMPs), galaxy clusters represent the best targets to search for gamma-ray signals induced by the decay of WIMPs with masses at the TeV scale. Due to its sensitivity and energy range of operation (from a few tens of GeV up to tens of TeV), the Cherenkov Telescope Array (CTA) Observatory has a unique opportunity to test the decay of WIMPs with masses close to the unitarity limit, complementing the searches for DM from other gamma-ray observatories as well as direct and collider experiments. One of the most promising clusters in terms of expected DM annihilation/decay fluxes is Perseus. In the first years of operation the CTA Observatory is planning to search for both DM and cosmic-ray induced gamma-ray emissions in this cluster. In this talk, preliminary limits to the annihilation cross-section and decay lifetime of WIMPs with masses between 50 GeV and 100 TeV using simulated observations of Perseus with CTA will be presented.

Statistical and computational methods for the inference of a binary black hole in Mrk 501

• Gustavo Magallanes-Guijón

In this work, a multifrequency analysis (radio, optical, x-rays, and gamma rays) of the blazar Mrk 501 is presented. We analyze the light curves of this extragalactic object with different computational algorithms (analysis of variance, discrete Fourier transform, periodograms, wavelets transform, among others). With the help of numerical simulations and light curve fitting using elliptic Jacobi functions, we infer the presence of an eclipsing binary companion with periodicity ~228d.

Relativistic Scenario for a Binary BH system in Blazars

• Bryan Larios

Blazars are a type of Active Galactic Nucley (AGN) which jet points towards the observer. Their emission is variable in different time scales and at different wavelenghts. Some objets presents periodicity in their emission, like the blazar PG 1553+113. In this work we study a scenario to explain blazar periodicities with timescales of few years. The scenario is built on a binary supermassive black hole (SMBH) system where one of the two SMBH carries a jet. Furthermore, we are considering that the two SMBH have angular momentum and that one of them (central) is described by a Kerr black hole metric. We found estimations for the masses of the sources and the distance that separates the two SMBH.

Simulated performance of a 55 compact IACTs array at high altitude

• José Serna-Franco (Instituto de Física - Universidad Nacional Autónoma de México)

In modern astrophysics, the innovation of new instruments for the detection of high-energy particles is very relevant for the next generation of gamma-ray observatories such as SWGO (Southern Wide-Field Gamma-Ray Observatory). The HAWCS’s Eye telescope is a prototype of a proposed compact wide-field-of-view Imaging Air-Cherenkov Telescope (IACT). It is designed as a SiPM-based 61-pixel telescope featuring a sealed Fresnel optic, and a versatile DAQ. In the following work, the characterization of a simulated array of 55 HAWC’s Eye telescopes at 4,100 m a.s.l. is shown, considering single and stereoscopic observations with a different number of telescopes and configurations. This project was realized with the support of DGAPA PAPIIT IG101320. The authors thankfully acknowledge the computer resources, technical expertise, and support provided by the Laboratorio Nacional de Supercómputo del Sureste de México, CONACYT member of the network of national laboratories.

Searches of ALPs : Galactic Sources

• Alvaro Pratts (IF-UNAM)

Even though dark matter constitutes approximately 27$ \% $ of the Universe, it has been impossible to understand its nature and composition. Historically, the most favored candidate has been the WIMPs (Weakly Interacting Massive Particles), with the Supersymmetric neutralino being the most known candidate. However, it has not been observed any supersymmetric particle. Thus other candidates for dark matter have begun to emerge with more force and renewed interest. One of these is the $\textit{Axion like particle}$(ALP), a hypothetical light particle (in the range of $\sim\mu$ eVs) arising within theories beyond the standard model (BSM) as an extension of the Axion concept of QCD. The effect of the conversion of ALPs to photons should be observed in the spectrum of highly energetic astronomical gamma-ray sources. In the particular case of galactic sources, the total effect of this coupling is expected as attenuation of their spectrum at energies above several tens of TeVs. Thus, observatories like HAWC have a golden opportunity to explore the properties of ALPs in the range of masses of $\mu eV$. This work presents the calculation of the possible effect of the photon-ALP conversion observed as attenuation of the spectrum of eHWC J1908+063 —a high-energy source detected by the HAWC observatory. Limits on two fundamental parameters of this candidate, mass and coupling constant, are established.

Determination of chaotic behaviour in time series generated by charged particle motion around magnetized Schwarzschild black holes

• Radim Pánis (Institute of Physics, Silesian University in Opava)

We study behaviour of ionized region of a Keplerian disk orbiting a Schwarzschild black hole immersed in an asymptotically uniform magnetic field. In dependence on the magnetic parameter ***B***, and inclination angle ***θ*** of the disk plane with respect to the magnetic field direction, the charged particles of the ionized disk can enter three regimes: a) regular oscillatory motion, b) destruction due to capture by the magnetized black hole, c) chaotic regime of the motion. In order to study transition between the regular and chaotic type of the charged particle motion, we generate time series of the solution of equations of motion under various conditions, and study them by non-linear (box counting, correlation dimension, Lyapunov exponent, recurrence analysis, machine learning) methods of chaos determination. We demonstrate that the machine learning method appears to be the most efficient in determining the chaotic region of the ***θ−r*** space. We show that the chaotic character of the ionized particle motion increases with the inclination angle. For the inclination angles ***θ∼0*** whole the ionized internal part of the Keplerian disk is captured by the black hole.

Astrophysics in Central América and the Caribbean

• Jose Rodrigo Sacahui Reyes (Universidad de San Carlos de Guatemala)

The Central American and the Caribbean region has low scientific development indicators. Montero-Camacho et al. 2021 highlights four main factors for these: 1. Absences of Ph.D. programs; 2. Lack of postdoctoral opportunities; 3. Low to none economic incentives and 4. Poor infrastructure. Most of the production in the last 20 years comes from Puerto Rico, the country that hosted the Arecibo International Radio Telescope, followed by Cuba and Costa Rica. The numbers are in contrast with the scientific production of neighboring countries such as México, where UNAM employs more lecturers/researchers in astronomy than all Central American institutions.These numbers are unlikely to change in the close future due to problems in science funding and the diminish of the Gross Domestic Product in recent years. To tackle this problem several efforts are being done. With time programs like summer schools, mentorships, research internships can change the current situation.In this talk I present the recent, ongoing and future work of a group of Central Americans/Caribbeans, and persons related to the region, working for the development of the Astronomical Sciences in the region.

The Plasma Window as a Vacuum-atmosphere Interface for Measurements of Stellar Neutron-induced Reaction Cross Sections

• Ophir Ruimi

Neutrons play a dominant role in the stellar nucleosynthesis of heavy elements. We review a scheme for the experimental determinations of neutron-induced reaction cross sections using a high-intensity neutron source based on the 18O(p,n)18F reaction with an 18O-water target at SARAF’s upcoming Phase II. The quasi-Maxwellian neutron spectrum with effective thermal energy kT ≈ 5 keV, characteristic of the target (p,n) yield at proton energy Ep ≈ 2.6 MeV close to its neutron threshold, is well suited for laboratory measurements of MACS of neutron-capture reactions, based on activation of targets of astrophysical interest along the s-process path. 18O-water’s vapour pressure requires a separation in between the accelerator vacuum and the target chamber. The high-intensity proton beam (in the mA range) of SARAF is incompatible with a solid window in the beam’s path. Our suggested solution is the use of a Plasma Window, which is a device that utilizes ionized gas as an interface between vacuum and atmosphere, and is useful for a plethora of applications in science, engineering and medicine. The high power dissipation (few kW) at the target is expected to result in one of the most intense sources of neutrons available at stellar-like energies. Preliminary results concerning proton beam energy loss and heat deposition profiles for target characteristics and design, a new full-scale 3-dimensional computer-aided design model of the Plasma Window (as well as its operation principles) and the planned experimental scheme, will be reviewed.

Filling the gap between neutron star and black hole masses

• Jorge Horvath (IAG-USP)

The lack of objects between $2$ and $5 \, M_{\odot}$ enter code here in the joint mass distribution of compact objects has been termed "mass gap" and attributed to the characteristics of the supernova mechanism at their birth. However, recent observations show that a number of candidates reported to lie inside the "gap" may fill it, and the paucity may be the result of small number statistics. We quantify in this work the individual candidates and evaluate the joint probability of a mass gap, working in a frequentist and Bayesian approach. Our results show that a mass gap is not present, to a very high confidence level. It remains to be seen if a relative paucity of objects ensues and how this population can be related to the formation processes, which may include neutron star mergers, collapse of a neutron star to a black hole and others.

Evaporation Black Holes in the Early Universe and the Hubble Tension

• Tsvi Piran (The Hebrew University)

TBA

Black holes in the Early Universe

• Felix Mirabel (IAFE)

The existence of supermassive black holes (SMBHs) of ∼ 109 solar masses in quasars at z ∼ 7.5, when the Universe was ∼700 Myr old, is an intriguing puzzle because their originremains unconstraint. It have been proposed that those SMBHs result from rapidly growing BH seeds of stellar and/or intermediate masses BHs at redshifts z ∼30. However, there is no consensus on whether such extreme rapid mass growth of BHs may be sustainable during the 600 hundred million years since the Bi Bang. Direct detections in the near and mid-infrared of galaxies and massive BHs at z = 7 to 16 with the JWST, and indirect detections of radio loud BH signals in the redshifted 21cm line of HI at z∼20 with radio arrays as SKA, may constrain the ultimate origin of the SMBHs observed up to z ∼7.5. In this talk I will discuss these issues along the lines of a review of open access published in New Astronomy Reviews 94, 101642 (2022).

Identity for scalar-valued functions of tensors and its applications in classical field theories and gravity

• Jürgen Struckmeier (GSI)

We present a theorem on scalar-valued functions of tensors, where ”scalar” refers to absolute scalars as well as relative scalars of weight w. The theorem thereby generalizes an identity referred to earlier by Rosenfeld in his publication ”On the energy-momentum tensor” and provides a (1,1)-tensor identity which can be regarded as the tensor analogue of the identity following from Euler’s theorem on homogeneous functions. The remarkably simple identity is independent of any internal symmetries of the constituent tensors, providing a powerful tool for deriving relations between field-theoretical expressions and physical quantities. We apply the identity especially for analyzing the relation of metric and canonical energy-momentum tensors of matter and gravity. The identity allows to formulate an equivalent representation of a generalized Einstein field equation for arbitrary model Lagrangian of vacuum space-time dynamics — including torsion and non-metricity.

On the cosmological constant in the De Donder-Weyl Hamiltonian formulation of gauge gravity

• David Vasak (Frankfurt Institute for Advanced Studies)

A modification of the Einstein-Hilbert theory, the Covariant Canonical Gauge Gravity (CCGG), leads to a cosmological constant that represents the energy of the space-time continuum when deformed from its (A)dS ground state to a flat geometry . CCGG is based on the canonical transformation theory in the De Donder-Weyl (DW) Hamiltonian formulation. That framework “deforms” the Einstein-Hilbert Lagrangian of the free gravitational field by a quadratic Riemann-Cartan concomitant. The theory predicts a total energy-momentum of the system of space-time and matter to vanish, in line with the conjecture of a “Zero-Energy-Universe" going back to Lorentz (1916) and Levi-Civita (1917). Consequently a flat geometry can only exist in presence of matter where the vacuum energy of matter is balanced by the vacuum energy of space-time. The observed cosmological constant is then just a a residual energy imbalance emerging from deviations from a flat geometry, torsion of space-time, and quantum gravity corrections. The constants of nature, Newton's G and Einstein's \Lambda, are mapped onto the coupling constants of CCGG.

Development of an analytical model for TeV Halos

• Fernanda Carreon (Instituto de Astronomía, UNAM)

TeV Halos are regions of extended emission around pulsars, produced due to inverse-Compton scattering of photons by particles accelerated inside and diffused away from the pulsar wind nebulae. TeV Halos, discovered in 2017 by the HAWC Collaboration, represent a possible detection tool for “silent” pulsars, those whose radiation jets are never oriented towards Earth. In addition, TeV Halos are very energetic cosmic accelerators and represent an uncharacterized population of gamma-ray sources that contribute to the galactic and extragalactic diffuse gamma-ray background. Finally, given their high-energy emission, these halos are potential probes for the search for Dark Matter. Thus, improvement of techniques to search for Halos is very important. In this work, we present a simulation of the gamma-ray emission of Geminga and Monogem side-by-side with the observations by HAWC. We use a simplified model for the emission based on pulsar characteristics. This project was supported by DGAPA PAPIIT IG101320.

Exploring a Magnetic Warm Inflationary Scenario

• Angel Sánchez (Facultad de Ciencias, Universidad Nacional Autónoma de México)

In this work we study the consequences a possible primordial magnetic field could have on the inflaton effective potential, taking as the underlying model a warm inflation scenario, based on global supersymmetry with a new-inflation-type potential. In the warn inflation scenario, the decay scheme for the inflaton field is a two-step process of radiation production, where the inflaton couples to heavy intermediate superfields, which in turn interact with light particles. In this context, by considering that the heavy and light sectors are charged, we work in the strong magnetic field approximation for the light fields. Our findings show that the trend of the magnetic contribution is to make the potential flatter, preserving the conditions for a successful inflationary process. This result is backed up by the behavior of slow-roll parameter ε. The viability of this magnetic warm inflation scenario is also supported by the estimation of the effect of the magnetic field on the heavy particles decay width.

A novel multimessenger study of Starburst galaxies: implications for neutrino astronomy

• Antonio Marinelli (Università di Napoli, Federico II)

Starburst galaxies (SBGs) and more in general starforming galaxies represent a class of galaxies with a high star formation rate (up to 100 Mo/year). Despite their low luminosity, they can be considered as guaranteed “factories” of high energy neutrinos, being “reservoirs” of accelerated cosmic rays and hosting a high density target gas in the central region. The estimation of their point-like and diffuse contributions to the neutrino astrophysical flux measured by IceCube can be crucial to describe the diffuse neutrino spectral features as well as the peculiar point-like excess like NGC1068. To this aim we used the most updated gamma-ray catalog of this class of objects to perform a multimessenger study and describe their gamma-ray emission through a calorimetric scenario. A whole sky analysis was performed through a blending of the measured spectral indexes and obtained a multi-component description of extragalactic background light (EGB), high energy starting events (HESE) and high-energy cascade IceCube data. Remarkably, we found that, differently from recent prototype scenarios, the spectral index blending allows starburst galaxies to account for up to 40% of the HESE events at 95.4% CL and favors a maximal energy of the accelerated cosmic rays at tens of PeV. The same calorimetric approach has been applied also to the known SBGs within 100 Mpc, considering, where possible, a source-by-source description of the star formation rate obtained from IR and UV observations. On this regard we showed how Future CTA measurements will be crucial to link the observed gamma-ray fluxes from resolved SBGs with their star-forming activity as well as to disentangle the cosmic-ray transport inside the core of these galaxies. The expected neutrino emission, related to this scenario, are then compared with what can be expected from the Global Neutrino Network.

Inflation models embedded in Lee-Wick theories

• Gabriella Piccinelli Bocchi (Universidad Nacional Autónoma de México)

Cosmological models supported by Lee-Wick theories have the interesting feature of a cosmological bounce that solves the singularity problem. Besides, non-canonical fields, which are present in these theories, may be invoked to provide scenarios of dark energy or inflation. In inflation, some desirable features are present, such that the slow-roll conditions and the tensor- to-scalar relationship are more easily satisfied compared to canonical inflationary models. We present here work in progress concerning an inflationary model that includes higher derivatives in the scalar field. We explore the effect of these higher derivatives on its effective potential and its decay process, in the framework of warm inflation.

Highlights from the X-ray all-sky survey eROSITA mission on AGN

• Thomas Boller

A). Ionized Gas Outflows in AGN from the gravitational radius scale up to the kiloparsec scale: We present the first look to the spectral and timing analysis of Narrow-Line Seyfert 1 Galaxies (NLS1s) with eROSITA based on the SDSS DR12 catalogue. The SDSS DR12 spectral analysis is based on a power-law model using XSPEC fit with a Principal Component Analysis (PCA) background model. The photon index distribution is asymmetric with a mean value of about 3, as expected from previous X-ray studies. Interestingly, about 10 per cent of the sources are in the super-soft tail with photon indices reaching values between 4 and 10. These sources are of further interest as the source counts run into the X-ray background at values at around 1 keV. We argue that ultra-soft ionized X-ray outflows have been detected eROSITA, which is supported by subsequent XMM-Newton DDT observations of 4 of the most extreme objects. By analyzing the asymmetry index of the optical emission lines in combination with X-ray eROSITA and XMM-Newton spectral properties, we detect outflows from the innermost few gravitational radii up to the kiloparsec scale. We analyzed intrinsic X-ray variability using standard and Bayesian methods and correlate the variability to the multi-wavelength properties during the individual survey scans as well as between the survey scans. B). The nature of extreme ultra-soft X-ray variability in 1H0707-495 first detected by eROSITA: One of the most prominent AGNs, the ultra-soft Narrow-Line Seyfert 1 Galaxy 1H0707-495, has been observed with eROSITA as one of the first CalPV observations on October 13, 2019, for about 60.000 seconds. The 2019 spectrum is drastically different from other AGN spectra observed so far, as it is much more variable at low energies up to only 0.8 keV, which has been referred to by Parker et al. (2022) as a new AGN ultra-soft state. The simultaneous XMM-Newton spectra show the same basic shape. We showed that the unusual soft X-ray variability, first detected by eROSITA, is due to a combination of an obscuration event and strong suppression of the variance at 1 keV by photoionized emission. An ionized partial coverer and strong relativistic reflection explain the unique X-ray softness. During the eROSITA observations, 1H 0707-495 showed, in addition, a dramatic flux drop by a factor of about 100 in just one day. This variability is primarily in the soft band and is much less extreme in the hard band. Such extremely large-amplitude variability has been observed in the past only in a few AGNs such as IRAS 13224-3809 (Boller et al. 1997), GSN 069 (2019Miniutti et al. 2019), and RX J1301.9+2747 (Giustini et al. 2020). In the combined eROSITA and XMM-Newton observation, 1H 0707-495 was caught in the historically lowest hard-flux state-observed so far.

Studying Primordial Non-Gaussianity with LSS tracers

• Jennifer Meneses Rizo

Considering that inflation is the mechanism that introduces the seeds for the formation of structures which distribution is close to Gaussian, generating a universe similar to ours introducing deviations from Gaussianity in the initial conditions could give us information about this inflationary period. In particular, the local primordial non-Gaussianities that generate a scale-dependent bias between the density of matter and the density of galaxies are studied, which makes their signal increase at large scales. Enhancement of the PNG signal makes it possible to search for, measure, and constrain it with large-scale structure tracers such as QSOs, LRGs, and ELGs. In this talk I will present the methodology for measuring PNG parametrized by the FNL factor from LSS of the Universe and some results of the validation process of this pipeline with simulations.

The BAO method and the DESI experiment

• Alejandro Perez Fernandez (Instituto de Física, UNAM)

Before the epoch of recombination, the Universe was permeated with a baryon-electron-photon plasma. While gravity gave rise to the collapse of the initial overdensities, the radiation pressure served as a counterforce, thus resulting in the free propagation of sound waves within the primordial plasma. This corresponds to the oscillatory pattern that can be observed in the CMB two-point statistics and is referred to as the Baryon Acoustic Oscillations (BAO) phenomena. Furthermore, the same feature can be measured in the two-point statistics of the late-time large-scale structure clustering of galaxies. The characteristic scale associated to the oscillations can then be used a standard ruler, which in turn can served as a powerful probe of Dark Energy. The Dark Energy Spectroscopic Instrument (DESI) is currently on a 5-year quest to measure the spectra of more than 30 million galaxies in order to produce the most comprehensive 3D map of the Universe ever created. One of the main objetives of the DESI Collaboration is the measurement of the BAO feature. With the expected level of accuracy in mind, it becomes paramount to revise the methodology of the BAO method.

Hot and Massive White Dwarfs: importance of general relativity and nuclear reactions in their structure and stability

• Manuel Malheiro

The structure and stability of hot and massive white dwarfs against radial oscillations, pycnonuclear reactions, and inverse β-decay are investigated, We find that the temperature produces importante effects on the equilibrium and radial stability of white dwarfs. The stable equilibrium configuration results are compared with those for white dwarfs estimated from the Extreme Ultraviolet Explorer survey and the Sloan Digital Sky Survey. We derive masses, radii, and central temperatures for the most massive white dwarfs according to the surface gravity and effective temperature reported by the surveys. We note that these massive stars are in the mass region where general relativity effects are important, and also near the threshold of instabilities due to radial oscillations, pycnonuclear reactions, and inverse β-decay. Regarding the radial stability of these stars as a function of the temperature, we find that it decreases with the increment of central temperature.

Neutron Star or Neutral Star - the 90-anniversary of Landau (1932)

• Renxin Xu (School of Physics, Peking University)

What is the real nature of compact stars/pulsars? This is a question historically judged exactly 90 years ago by Lev Landau for the first time, and is also focused to be the first big problem to be solved in this era of multi-messenger astronomy, including the gravitational-waves. Nucleons were supposed to be elementary particles in Landau’s time, but actually quarks are instead in the standard model of particle physics. I would like to explain that Landau’s original idea should be improved if one thinks in the same way with the inclusion of strangeness in today’s physics. More and more astrophysical phenomena, e.g., cosmic Gamma-ray bursts and fast radio bursts, are closely coupled with the answer to the big problem.

LIGO Compact Binaries from Isolated Stellar Binaries

• Aldo Batta (INAOE)

Since the first detection of gravitational waves on September 14 2015, there have been over 90 different GW events detected by LIGO. One of the formation scenarios for such compact binaries involve the evolution of isolated stellar binaries, which undergo multiple mass transfer episodes that ultimately lead to the formation of a tight binary composed of two compact objects such as neutron stars or black holes, product of the death of the massive stars. In this work, we explore the scenario of the formation of the second compact object through a supernova explosion. The energy deposited on the explosion will ultimately determine if a NS or BH is formed, its spin, and the amount of material accreted by the companion. As a result we’re able to calculate the effective spin of the resulting compact binary and compare it with LIGO observations. We find that this scenario produces systems with effective spins consistent with what is observed by LIGO.

Techniques in HAWC Observatory for classification of the air showers

• Tomás Capistrán (IA-UNAM)

One of the main challenges of the HAWC Observatory is to separate showers produced by gamma-rays from those produced by charged particles that represent almost 99.9% of the total particles arriving on Earth. HAWC applies a technique to distinguish them and to remove the most hadron-induced showers considered in the analysis. In this work, some techniques that have been applied to the HAWC data are described. One is the official that uses a simple cut on two parameters, and the other two techniques use machine learning. All these techniques are used and compared to observe three astrophysical sources (the Crab Nebula, and two blazars). We acknowledge the support from DGAPA PAPIIT IG101320.

Correlation between X-rays and TeV gamma-rays in blazars

• Mabel Osorio (IA-UNAM)

The spectral energy distribution (SED) of blazars is described by two radiative components, which are commonly modeled within the standard one-zone synchrotron self-Compton (SSC) leptonic framework. In this model, it is expected a strong correlation between energy band fluxes of the SED components, such as between soft X-ray and TeV gamma-ray fluxes. The correlations previously reported for some sources are often in small periods of time and are described by a broad variety of functions, from linear to almost cubic correlations. Even for the same source, several types of correlations have been reported. To know if there is a unique correlation behavior per source or in general for all sources, a long period of observation is required for several sources. In this work, we present the long-term soft X-ray vs TeV gamma-ray correlation of 4 HBL blazars at z<0.1 and try to find common behaviors between them. We acknowledge the support from DGAPA PAPIIT IG101320.

Different modern methods for constructing equilibrium models of uniformly rotating compact stars

• Dániel Barta (Wigner RCP)

In recent years we have collected essential information on the integral parameters of neutron stars from multi-messenger observations of binary neutron-star mergers. In the light of these observations, we investigate the effects of rapid rotation on the structure and observable parameters of rapidly rotating relativistic compact stellar models based on the angular velocity and on the equations of state. We construct uniformly rotating stellar solutions to quartic order in the angular velocity in a Hartle–Thorne slow-rotation expansion, while for rapidly rotating stars, we solve the coupled system of non-linear elliptic PDEs that are associated with the Einstein field equations by implementing multi-domain spectral methods in the LORENE/rotstar codes. The multipole moments are extracted from the numerical stellar solutions are compared with the quartic-order slow-rotation approximation in the low spin-frequency regime.

Search for GRBs possibly associated with GW using HAWC

• Yunior Frainen Pérez Araujo (IA-UNAM)

Detecting gravitational waves (GWs) associated with Gamma-ray bursts (GRBs) has reaffirmed their importance and interest. In particular, short GRBs have been associated as the electromagnetic counterpart of GWs, the first being the burst GRB 170817A associated with the event GW170817. Due to its large field of view and duty cycle and its many improvements in the reconstruction of events, HAWC is an ideal observatory to study transient phenomena during and after the main emission in the TeV energy regime. In this work, we present the search for TeV emission in the HAWC Observatory from the trigger time to 200 days in GRB 170817A and others with similar characteristics to this burst. We acknowledge the support from PAPIIT IG101320 and IN105921.

Deducing Neutron Star Equation of State From X-ray Telescope Spectra with Machine Learning

• Delaney Farrell

Neutron stars provide a unique laboratory for studying matter at extreme pressures and densities. While there is no direct way to explore their interior structure, X-rays emitted from these stars can indirectly provide clues to the equation of state (EOS) of the nuclear matter within through the inference the star’s mass and radius. However, inference of EOS directly from a star’s X-ray spectra is extremely challenging from systematic uncertainties in observation. The current state of the art is to use simulation-based likelihoods in a piece-wise method, which first infer the star's mass and radius to reduce the dimensionality of the problem, but likely sacrifice some information, and from those quantities infer the EOS. We demonstrate a series of enhancements to the state of the art, in terms of realistic uncertainty quantification and improved regression of physical properties with machine learning. We also demonstrate the first inference of the EOS directly from the high-dimensional spectra of observed stars, avoiding the intermediate mass-radius step. Our network is conditioned on the sources of uncertainty of each star, allowing for natural and complete propagation of uncertainties to the EOS.

Gravitational Waves Astronomy - Breakthrough Discoveries

• Dorota Rosinska

I will review the Ligo-Virgo-Kagra breakthrough discoveries and discuss their importance for astronomy, fundamental physics and cosmology.

The effects of a minimal length on the structure of black holes within the pseudo-complex General Relativity

• Peter Otto Hess (Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico)

The effects of a minimal length, on the structure near the event horizon of a Schwarzschild black hole, are investigated within the pseudo-complex General (pcGR) Relativity. It is shown that for small mass black holes there are strong effects, e.g., avoiding the accumulation of mass which might be important in the formation of black holes during the Big Bang. The pcGR adds to the metric a contribution characterized by a parameter, which has a critical value at which barely an event horizon exists. For macroscopic black holes, these effects vanished for below and above this critical value, but at the critical value effects still persist though quickly disappearing. For very large mass black holes the minimal length can be safely neglected. The limit between a small and a macroscopic black hole, in units of length, is between $10^{15}$cm and $10^{13}$cm.

Weyl and Majorana for Neutral Particles

• Valeriy Dvoeglazov

We compare various formalisms for neutral particles. It is found that they contain unexplained contradictions. Next, we investigate the spin-1/2 and spin-1 cases in different bases. Next, we look for relations with the Majorana-like field operator. We show explicitly incompatibility of the Majorana anzatzen with the Dirac-like field operators in both the original Majorana theory and its generalizations. Several explicit examples are presented for higher spins too. It seems that the calculations in the helicity basis only give mathematically and physically reasonable results. They can be discussed in the context of recent observatioal controversies with solar and atmospheric neutrinos.

Equations of State for Dense Matter

• Veronica Dexheimer

Due to the present large uncertainty in the composition and interactions of dense nuclear matter, there are many different equation of state (EoS) models that can fulfill nuclear and astrophysical constraints. EoS repositories allow for a fast exchange of EoS between providers and simulation users, accelerating our understanding of dense matter. I discuss different EoS repositories, focusing on the MUSES infrastructure, and different EoSs, focusing on the CMF model.

Landau-Lifshitz and Weinberg energy-momentum complexes for a f(R)-modified gravity black hole solution with electric and magnetic charges

• Irina Radinschi (Department of Physics, Gheorghe Asachi Technical University, Iasi)

The problem of energy-momentum localization for a four-dimensional, spherically symmetric, electrically as well as magnetically charged black hole solution in a $f(R)$-type modified gravity with $(R)=R+2\beta \sqrt{R-8\Lambda}$ is studied. Asymptotically this solution behaves as an AdS or dS space-time, while it transforms to the Reissner-Nordstr\"{o}m solution in the case of zero magnetic charge. The energy and momentum distributions are computed by utilizing the Landau-Lifshitz and the Weinberg energy-momentum complexes. In both prescriptions all the momenta vanish, while the energy is found to depend on the electric and the magnetic charge, the mass $m$, the dimensional metric parameter $\beta $, the cosmological constant $\Lambda$, and the radial coordinate $r$. The behavior of the energy is examined near the origin and near infinity, while the special case of zero electric charge is also considered. Furthermore, some investigations of a possible astrophysical interest are performed.

Revisiting the approximations on the cosmological solutions of ultra-light axions

• Luis Ureña-López

Ultra-light axions are promising dark matter candidates, but the computation of their cosmological observables is challenging because of the rapid oscillations of the axion field around the minimum of its potential. Different approaches have been discussed in the literature to avoid such difficulty, mainly by using approximated formulas for the axion equation of state and sound speed. Here, we revisit an alternative method that makes a change of variables and which allows to spot more easily the rapidly oscillating terms in the equations of motion. Such terms can be cut-off directly in the differential equations without spoiling the accuracy of the final output, and without manipulating the equation of state and the sound speed. A comparison between numerical and semi-analytical is shown to asses the appropriateness of the method to solve the original axion equations.