OCTOBER 28

Juan Carlos Hidalgo

Title: Applying SFDM phenomena to scalar fields in reheating

Chanda Prescod-Weinstein

Title: Imprints of Microphysics on Large Scale Structure

Abstract: In this talk, I will describe my efforts to understand the nature of the mysterious dark matter. I will give some insight into how I am using a range of tools -- model building, computation, and neutron stars -- to get at the basic question of “what is the statistical mechanics of axion dark matter?” I will show that the details of ultralight axion models can shift the astrophysical phenomenology and also that neutron stars are potentially interesting dark matter constraint laboratories. From the optical to the X-ray and gamma-ray universe, astrophysics has a role to play in understanding the details of this major problem in particle physics.

Brian Nord

Title: Imagining the future of AI-augmented science experiments: Can we trust machines with discovery?

Alma X. González Morales

Title: Constraints to ultralight axion dark matter particles mass: the effect of self-interactions

Abstract: Ultralight axions have gained great relevance in modern cosmology, becoming a promising candidate to describe the dark matter of the Universe. Axion models in which the scalar field potential includes only the quadratic term, usually referred to as the free case, have been extensively studied in the literature. A distinctive signature of these models, with respect to the standard cold dark matter, is the presence of a cut-off in the mass power spectrum and the prediction of cored density dark matter halos. However, such models do not capture all the implications that arise when including a full axion potential. In this talk, I will discuss some results of studies of the cosmological evolution of linear perturbations, and its comparison to the cold dark matter and the free case, which reveals an enhancement in the amplitude of the mass power spectrum just before the cut-off scale, due to the non–linearity of the axion–like potential. As well, I will discuss current and future observational constraints that could help us assess the importance of self-interactions.

Nathan Musoke

Title: New Simulations of Ultralight Scalar Field Dark Matter

Abstract: In this talk I will discuss ongoing simulations of ultralight scalar field dark matter. I will present a new code, UltraDark.jl and some applications. I will discuss ongoing work to understand the effect of self interactions on the stability of ultralight dark matter halos. Then I will discuss preliminary simulations of multiple scalar dark matter fields. These fields can interact to produce phenomena not seen with a single field. To end, I will discuss how expertise with scalar dark matter fields can be translated to the reheating epoch of the early universe.

Daniel Grin

Title: Ultra-light axions and CMB anisotropies from degree to arcminute scales

Abstract: Ultra-light axions are a well-motivated candidate for dark matter and dark energy, motivated both by considerations from high-energy theory and observational challenges to the Lambda CDM cosmological paradigm. We will summarize the motivation to consider such a dark-sector component, and explore empirical consequences, ranging from the primary anisotropies of the CMB to late-time secondary anisotropies imprinted by gravitational lensing and Compton scattering in galaxy clusters, to local precision measurements. We will explore the potential of upcoming experimental efforts to critically test the ultra-light dark-sector parameter space.

OCTOBER 29

Nicolás Sanchis-Gual

Title: Dynamical bosonic stars and gravitational waves

Abstract: Bosonic stars are theoretical exotic compact objects made of ultralight bosonic particles that could explain part of dark matter. In this talk, I will review some recent results on the stability and dynamical formation of these objects. Then I will talk about bosonic star mergers, the emission of gravitational waves, and what we could learn about them from a real gravitational wave event, if these stars exist in the Universe.

Tanja Rindler-Daller

Title: New results on structure formation in scalar field dark matter

Abstract: In this talk, I will report on very recent findings regarding linear structure formation and the spherical halo collapse model in scalar field dark matter (SFDM) with strongly repulsive self-interaction, also referred to as the Thomas-Fermi regime (SFDM-TF). We established for the first time that a core-envelope halo structure arises in SFDM-TF, similar to what has been previously found for fuzzy dark matter (FDM). For kpc-size halo cores, SFDM-TF is able to resolve the small-scale problems of cold dark matter and fares better than FDM. However, linear structure formation actually favours sub-kpc cores, with subtle implications for the small-scale crisis of cosmology.

Lam Hui

Title: Wave interference substructure and vortices for light scalar dark matter

Abstract: We will discuss the generic expectations for wave interference substructure in a dark matter halo composed of a light scalar such as an axion or axion-like-particle. We will in particular talk about vortices and their manifestations in astronomical observations and direct detection experiments. If time permits, we will discuss vortices as black hole hair.Title: Wave interference substructure and vortices for light scalar dark matter.

Jordi Solís López

Title: Scalar field dark matter as an alternative explanation for the anisotropic distribution of satellite galaxies

Abstract: The scalar field dark matter also called ultralight bosonic dark matter, has received considerable attention due to the number of problems it might help to solve. Among these are the cusp-core problem and the abundance of small structures of the standard cold dark matter model. In this talk, we show that multi-state solutions of the Gross-Pitaevskii-Poisson equations, interpreted as galactic halo density profiles, can provide a possible explanation to the anisotropic distribution of satellite galaxies observed in the Milky Way, M31 and Centaurus A, where satellites trajectories seem to concentrate on planes close to the poles of the galaxies instead of following homogeneously distributed trajectories. In order to construct a proof of concept, we study the trajectories of a number of test

particles traveling on top of the gravitational potential due to a multi-state halo with monopolar and dipolar modes. The result is that particles accumulate asymptotically in time on planes passing close to the poles. Satellite galaxies are not test particles but interpreted as such, our results indicate that in the asymptotic time their trajectories do not distribute isotropically, instead, they prefer to have orbital poles accumulating near the equatorial plane of the multistate halo. The concentration of orbital poles depends on whether the potential is monopolar or dipolar dominated.

Tonatiuh Matos

Title: The graviton Compton mass as Dark Energy

Abstract: In Rev.Mex.Fis. 67(2021)040703 it was shown that by considering the quantum nature of the gravitational field mediator, it is possible to introduce the momentum energy of the graviton into the Einstein equations as an effective cosmological constant. The Compton Mass Dark Energy (CMaDE) model proposes that this momentum can be interpreted as dark energy, with a Compton wavelength given by the size of the observable universe $R_H$, implying that the dark energy varies depending on this size. The main result of this previous work is the existence of an effective cosmological constant $\Lambda=2\pi^2/\lambda^2$ that varies very slowly, being $\lambda=(c/H_0) R_H$ the graviton Compton wavelength. In the present talk we use that the dark energy density parameter is given by $\Omega_\Lambda=2\pi^2/3/R_H^2$, it only has the curvature $\Omega_k$ as a free constant and depends exclusively on the radiation density parameter $\Omega_r$. Using $\Omega_{0r} = 9.54\times10^{- 5}$, the theoretical prediction for a flat universe of the dark energy density parameter is $\Omega_{0\Lambda} = 0.6922$. We perform a general study for a non-flat universe, using the Planck data and a modified version of the CLASS code we find an excellent concordance with the Cosmic Microwave Background and Mass Power Spectrum profiles, provided that the Hubble parameter today is $H_0 = 72.6$ km/s/Mpc for an universe with curvature $\Omega_{0k}=-0.003$. We conclude that the CMaDE model provides a natural explanation for the accelerated expansion and the coincidence problem of the universe.

Francisco Guzmán

Title: Virialization of BEC cores

Juan Carlos Degollado

Title: l-Boson Stars

Abstract: In this talk I will review some properties of solutions to the static, spherically symmetric Einstein-Klein-Gordon system for a collection of an arbitrary odd number N of complex scalar fields with an internal U(N) symmetry and no self-interactions known as l-boson stars. These new solutions are compact, globally regular, configurations of self–gravitating boson fields characterized, besides the mass of the field, by an angular momentum number.

PARALLEL SESSION A

Luis Enrique Padilla Albores

Title: A new mechanism for primordial black hole formation during reheating

Abstract: In this talk, we explore the possibility of primordial black holes (PBHs) forming from the gravitational collapse of either the structures virialized during reheating, or from the collapse of the central core of these configurations. We compute the threshold amplitude for the density contrast to undergo this process, for both the free and self-interacting scalar fields. We discuss our results in light of the constraints to PBHs abundances at the lower end of the mass spectrum.

Belen Carvente Mendoza

Title: Scalar field dark matter with two components: combined approach from particle physics and cosmology

Abstract: We explore the possibility of incorporating particle physics motivated scalar fields to the dark matter cosmological model, along with the successful modeling performed by the classical complex scalar field and without spoiling the advantages that this model gives, particularly, the one related to the existence of certain region in the parameter space, which increases the number of neutrino species N_eff in the correct amount needed in the early Universe to be consistent with the observed abundance of light elements produced at Big Bang Nucleosynthesis (BBN).

Stefany Guadalupe Medellín González

Title: Quick simulations for a Scalar Field Dark Matter (SFDM) model

Abstract: In this work we explore the structure formation of the Universe using a Scalar Field Dark Matter (SFDM) mode. The SFDM model proposes that the dark matter is a very light boson particle with a mass around 10^-22 eV, which is coupled to other particles only gravitationally. This model has a natural cut-off in its linear mass power spectrum that translates in the suppression of structure at small scales; this characteristic can open the possibility to distinguish it from LCDM. We implement the model on a hybrid code that uses 2LPT theory for large scales and an N-body for small scales. For the analysis, we use the mass power spectrum as an observable to make comparison between the LCDM and SFDM models.

Víctor Manuel Jaramillo Pérez

Title: Different paths to increase the compactness of a boson star

Abstract: The inclusion of a scalar field as a source in the Einstein equations allows to obtain useful and simple models, whether this form of matter turns out to correspond completely with the specific properties of dark matter or if it is used only as a reference and starting point towards other more complex models. It is of interest in the study of compact objects, to find solutions of this simple model (and its variants) with high compactnesses, that is, with large masses contained in small radii, so that they are objects comparable with neutron stars or black holes. Restricting myself to Einsteinian gravity I will briefly describe the different paths that exist for this and then focus on a couple of ways that exist within configurations that have an associated angular momentum variable, specifically the ell-boson stars.

Emmanuel Chávez Nambo

Title: On the existence of Newtonian $\ell$-boson stars

We present a proof for the existence of a discrete family of global, normalizable, static and spherically symmetric solutions of the generalized Schrödinger-Poisson system, which considers an odd number of N = 2 $\ell$ + 1 complex massive scalar fields of mass m and angular momentum $\ell$. These solutions, which in previous work have been constructed by numerical methods, are known as Newtonian ell-boson stars, and hence our result provides a rigorous mathematical description for these objects.

Erick Munive Villa

Title: Solving the Schrödinger Poisson Equation Using a Harmonic Potential Trap

Abstract: We have developed a code which solves the three-dimensional Schrödinger Poisson (SP) system and in this work we show some solutions for this code using a initially stationary configuration embebed in a Harmonic Potential Trap in order to simulate the evolution of an halo immersed in a bigger Dark Mater Halo.

PARALLEL SESSION B

Francisco Linares

Title: Composite Dark energy

Abstract: In this talk we review the cosmological evolution of a multi-component dark energy model. We analyze the implications of having two different components of dark energy coexisting simultaneously during the cosmic history, from the radiation domination era to the present day. We show that, once the corresponding statistical analysis is carried out, current information from data taken from astrophysical and cosmological sources indicate that it is possible to have an accelerated expansion of the Universe due to the combined dynamics of a phantom field and a negative cosmological constant.

Yadir Garnica

Title: Axion Dm, BAU and scalar wigs

Abstract: The intrinsic properties of the axion make it a great dark matter candidate. In this talk two scenarios will be presented that relate axion cdm production to the BAU problem and with the existence of scalar field wigs surrounding black holes.

Atalia Navarro Boullosa

Title: Bayesian analysis for rotational curves with $\ell$-boson stars as dark matter component

Abstract: The rotational curves were the second observable on giving us evidence of the existence of the dark matter, there for their use to fit the dark matter component in them is important. In this work we use scalar field dark matter, solving numerically the non- relativistic limit of the Einstein-Klein-Gordon system, the Schrödinger-Poisson system. These solutions, called ð-boson stars [1], are parametrized by an angular momentum number l = (N − 1)/2, an excitation number n, and a continuous parameter representing the amplitude of the fields.

We perform a $\chi^{2}$ for the cases with $\ell$ = 0 and the linear combinations of $\ell$- boson stars as a dark matter component, where we notice a better fitting using the linear combination. Then, we modified SimpleMC, a MCMC code to perform the parameter inference obtaining a better fit including other $\ell$ in our model, which is congruent with our previous result.

We choose Low Brightness Surface Galaxies (LBSG) to fit the free parameters in our model due to their characteristics allowed us to only considered the dark matter component.

Jessica Nayely López Sánchez

Title: Generalized Dark Matter in Compact Groups of Galaxies

Abstract: In this work, we have studied the Generalized Dark Matter (GDM) model, in which dark matter is described as a general fluid which includes (in some specific limits) a set of well known scenarios such as WDM, HDM and SFDM. This model represents an extension of CDM allowing three free parametric functions: the equation of state w(a), sound speed cs^2(a) and the viscosity speed cvis^2(a). We performed cosmological simulations using GDM for small structures in order to study Compact Groups of galaxies, namely, small isolated agglomerations of galaxies with high velocity dispersion. We studied the statistics of these groups candidates and their virialization behavior in order to compare them to the observed Compact Groups.

Omar de Jesús Cabrera Rosas

Title: Imaging formation for DM profiles: ray tracing using the gravitational refraction law

Abstract: The imaging formation process in halos for some dark matter proles is studied. We analyze the images generated on the lens plane by obtaining the analytical surface mass densities \Sigma(x) and their corresponding deflection angles \alpha(x), and later by applying a method for ray tracing using the gravitational refraction law.

Eric Santiago Escobar Aguilar

Title: Stochastic Processes in Scalar field

Abstract: The growing interest in the nature of dark matter has led to proposing different models that require the attention of different branches of research to obtain a theory as robust as it is

necessary. We are very interested in studying the scalar field dark matter models by using stochastic processes theory.

By using the hydrodynamic approach for the Klein-Gordon equation in curved spaces, from the continuity equation we obtain a diffusion equation for the scalar field in arbitrary space-time. This result can be used to express a diffusion equation for the Schwarzschild metric in the weak gravity field.