OCTOBER 27

Elisa Ferreira (Zoom)

Title: Narrowing the mass range of ultra-light dark matter

Abstract: In this talk I will discuss the latest efforts to constraint the mass of the ultra-light dark matter models, focusing on the current bounds on the fuzzy dark matter (FDM) model. I will show how we can use the different predictions of this model and different astrophysical systems to put the strongest bounds to date on the mass of this ultra-light axion, showing also the incompatibilities that are currently present in these bounds. I will also discuss the current developments in using interference patterns and vortices as a way to probe the FDM model.

Jowett Chan (Zoom)

Title: The Present and Future of Scalar Field Dark Matter Simulation

Abstract: The non-linear evolution of the Scalar Field Dark Matter (SFDM) is governed by the coupled Schroedinger-Poisson equations. We will recap some of the recently adopted numerical schemes by different groups, such as the spectral method and those applied to non-uniform mesh simulations, and discuss each of their advantages and limitations. Among all of the simulated wave phenomenology, we will focus on our recent finding, the diversity of the core-halo structure of the SFDM model, which is closely related to the observed inner structure of faint dwarf galaxies within the Milky Way. I will conclude with a prospect on the future direction for SFDM simulations.

Paul Shapiro (Zoom)

Title: Cosmology in a Universe with Complex Scalar Field Dark Matter (ΛSFDM)

Abstract: TBA

Tanja Rindler-Daller (Zoom)

Title: Cosmology of complex vs. real scalar field dark matter models: more than one world apart

Abstract: I will talk about further results concerning the cosmic evolution and structure formation of different complex and real scalar field dark matter models, with and without self-interaction. We have modified the Boltzmann solver CLASS in order to investigate new phenomena, including stiff phases in the early Universe. Our findings confirm and expand upon previous results in the literature.

Lam Hui (Zoom)

Title: Superradiance in the presence of accretion

Abstract: We will discuss how superradiance can act in tandem with accretion to create an unusually large superradiance cloud.

Tonatiuh Matos

Title: The quantum character of the Scalar Field Dark Matter

Abstract: The Scalar Field Dark Matter (SFDM) model, also called Fuzzy, Wave, Bose-Einstein, Ultra-light Dark Matter, has received a lot of attention because it has been able to provide simpler and more natural explanations for various features of galaxies, such as the number of satellite galaxies and the cusp-core problem. We recently showed that this model is able to explain the vast polar orbits of satellite galaxies around their host, the so-called VPO, and to explain the X-ray and gamma-ray emissions in the vacuum regions of our galaxy, that is, the Fermi Bubbles. In all these phenomena the quantum character of SFDM has been crucial. In this talk we study the quantum effects of SFDM at the cosmological level, to see these effects not only at the galactic scale but also at the cosmological scale. Using a convenient ansatz, we were able to integrate the perturbed equations to show that the shape of the SFDM halos resembling atoms is a generic result. The main conclusion of this work is that quantum mechanics, the successful microworld theory, could also explain the dark side of the cosmos.

OCTOBER 28

Hsi-Yu Schive (Zoom)

Title: Soliton Random Motion in Fuzzy Dark Matter

Abstract: I will address the soliton random motion in fuzzy dark matter (FDM), including its confined Brownian motion and density oscillations. The former leads to a new challenge against FDM since the resulting soliton tidal field may completely disrupt the ancient star clusters in the center of dwarf galaxies. In comparison, the heating from density oscillations is inefficient and adiabatic since the oscillation timescale is substantially longer than the characteristic timescale of a star cluster. Finally, I will discuss some challenges and opportunities for FDM, such as stellar disc thickening, multi-component FDM, and the construction of Milky Way-sized halos.

Miguel Megevand

Title: l-Boson Stars

Abstract: In this talk, we present a new, more general family of boson stars, named l-boson stars. despite being characterized by an angular momentum number l (hence de the name), l-boson stars are spherically symmetric, s is the case with standard, non-rotating boson stars, which are obtained as a subfamily in the particular cases when l=0. We will present these new solutions and describe their main properties, including stability, compactness, anisotropy, and geodesic motion.

Aldo Rodríguez Puebla

Title: A new semi-empirical model for the Galaxy-SMBH-halo connection

Abstract: In this talk I will introduce EMPIRE; a new model for the study of the galaxy-supermassive black hole-halo connection. EMPIRE uses a large battery of observations in order to constrain the space parameter that better mimics the observed universe, including the abundance of galaxies (since z~10) and quasars (since z~6), galaxy's sizes (since z~5) and star formation rates (since z~8), etc. I will show that EMPIRE predicts the dependence of the spatial clustering with the star formation rate of the galaxies since z~1 that is in good agreement with the ones derived from cosmological surveys. Finally, I'm going to discuss on how EMPIRE gives some hints on the effects of feedback from supernovae and AGNs on galaxy evolution, particularly for galaxies with low levels of star formation.

Carlos Herdeiro (Zoom)

Title: Black holes and ECOs: the imitation game and its limitations

Abstract: Ultralight bosons could form part (or the whole) of the dark matter budget of the universe. Moreover, they can form compact structures which are a robust example of exotic compact object (ECO): bosonic stars. In this talk we discuss the ability of such structures to imitate black holes, with concrete examples and real data. However, we will argue that whereas they can co-exist with black holes as another ingredient of the physical universe and, in some circumstances, be mistaken by them, they cannot replace entirely black holes. Some of the lessons taken from this model on the limitations on the imitation game could be generic for other families of ECOs.

Francisco Guzmán

Title: CAFE-FDM: a code that simulates the dynamics of ultralight bosonic dark matter

Abstract: We present a code that solves the Schroedinger-Poisson-Euler system of equations, intended to model de dynamics of Fuzzy Dark Matter plus baryons coupled through gravity, in structure formation scenarios. We describe the various numerical methods implemented and the diagnostics of the systems analyzed. As a test of fire of only dark matter, we show the collision of a number of solitons that give rise to the formation of a single core with a core profile itself, and a NFW tail profile. We then show a second test that involves also baryons, namely the effects induced by the baryonic matter on the process of core formation. Subtleties on the topology of the domain are raised and discussed.

Darío Núñez

Title: Exploring some combinations of scalar fields in the formation of compact objects

Abstract: We use the analytic and numerical machinery that we have developed in recent works, to solve the Einstein-Klein Gordon system and explore some non-conventional self gravitating distributions

OCTOBER 27

PARALLEL A

Ana A. Avilez López

Title: Effects of the Decay of Dark Matter on Large-Scale Structure Formation

Abstract: In the standard cosmological paradigm dark matter is modeled as a non-collisional fluid made of non-relativistic stable and neutral massive particles, this assumptions about the features of dark matter are required to predict diverse astronomical and cosmological observations such as the spectra of background cosmic radiation and its anisotropies and the matter distribution at scales above O(100 Mpc) . Nevertheless, the possibility that dark matter is made of non-stable particles is observationally viable, as long as dark matter half-life is much larger than the age of the universe. In this talk I will briefly present some constraints to the half-life and the fraction of decaying dark matter according to observations of redshift space distortions in the large scale structure distribution.

Andrés Bañares Hernández (Zoom)

Title: Fuzzy Dark Matter Confronts Galactic Rotation Curves of Dwarf Irregular Galaxies in the Local Group

Abstract: We test the consistency of ultra-light scalar field dark matter (ULDM) against a select sample of high-quality rotation curves from galaxies in the LITTLE THINGS and SPARC surveys. We focus on the axionic soliton + NFW model suggested by simulations in the literature with a broad range of particle masses (10^-25 – 10^-19 eV), obtaining good fits in most cases for the typical range of 10^-23 – 10^-22 eV. We also test for consistency with a number of predictions, such as abundance-matching, concentration vs halo mass and the soliton-halo mass relation, probing whether ULDM can address the small-scale issues of LCDM.

Atalia Navarro Boullosa

Title: Bayesian analysis for rotational curves with ℓ-boson stars as a dark matter component

Abstract: The rotational curves were one of the first observable to give us evidence of the existence of 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 ℓ-boson stars [2], 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 bayesian analysis modifying SimpleMC, a MCMC code to perform the parameter inference, for the cases with ℓ = 0, ℓ = 1 and multistates of ℓ- boson stars as a dark matter component, where we notice a better fitting for the multistates case. 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.

Iván Álvarez Ríos

Title: CAFE-FDM: a code that simulates the dynamics of ultralight bosonic dark matter

Abstract: We present a code that solves the Schroedinger-Poisson-Euler system of equations, intended to model de dynamics of Fuzzy Dark Matter plus baryons coupled through gravity, in structure formation scenarios. We describe the various numerical methods implemented and the diagnostics of the systems analyzed. As a test of fire of only dark matter, we show the collision of a number of solitons that give rise to the formation of a single core with a core profile itself, and a NFW tail profile. We then show a second test that involves also baryons, namely the effects induced by the baryonic matter on the process of core formation.

Stefany Medellín

Title: Quick simulations for Scalar Field Dark Matter model and Structure Formation

Abstract: In this work, we explore the structure formation of the Universe using a scalar field dark matter model (SFDM), which proposes that dark matter is a very light boson particle with a mass of around 10^-22 eV that it is only gravitationally coupled to other particles. This model has a natural cutoff in its linear mass power spectrum that can suppress small-scale structure; this feature allows you to differentiate it from LCDM. However, this model represents a challenge to solve at all scales and is more computationally expensive than the standard LCDM model, so it is important to generate new tools to solve the formation of this structure. For this reason, we implement the model in a hybrid code that uses 2LPT theory for large scales and an N-body for small scales, which makes this method faster than standard N-body simulations. For analysis, we use the mass power spectrum as an observable to make a comparison between the LCDM and SFDM models and an analysis of the halo mass function.

Luis Osvaldo Téllez Tovar

Title: Cosmological constraints on the Multi Scalar Field Dark Matter model

Abstract: The main aim of this work is to provide cosmological constraints on the Multi Scalar Field Dark Matter model (MSFDM), in which we assume the dark matter is made up of different ultra-light scalar fields. As a first approximation, we consider they are real and do not interact with each other. We study the equations for both the background and perturbations for N-fields and present the evolution of the density parameters, the mass power spectrum and the CMB spectrum. In particular, we focus on two scalar fields with several combinations for the potentials V (φ) =1/2m2φφ2, V (φ) = m2φf 2 [1 + cos(φ/f )] and V (φ)= m2φf 2 [cosh(φ/f ) − 1], however the work, along with the code, could be easily extended to more fields. We use the data from BAO, Big Bang Nucleosynthesis, Lyman-α forest and Supernovae to find constraints on the sampling parameters for the cases of a single field and double field, along with the Bayesian evidence. We found that some combinations of the potentials get penalized through the evidence, however for others there is a preference as good as for the cold dark matter.

PARALLEL B

Anton A. Lipovka (Zoom)

Title: In astrophysics and cosmology, dark matter is not required

Abstract: As is well known, in astrophysics and cosmology there are several observed phenomena, to explain which the concept of dark matter is usually involved. In this work, we discuss such phenomena and reasonably prove that such phenomena as rotational curves of spiral galaxies, gravitational lenses, the formation of the observed structure of the universe, etc. can be naturally explained in the framework of ordinary physics. Thus, there is no need to attract unobserved entities in the form of dark matter.

Sebastián Nájera Valencia

Title: Szekeres-II models in cosmology

Abstract: In recent years there have been advances in Szekeres-II models which previously were thought to be unphysical. Since this models admit an imperfect fluid as matter content, and in general they have no symmetries, in this talk we will show some results which indicate Szekeres-II solutions could be used as toy models for inflation and insights on the Hubble constant tension.

Erik Jiménez Vázquez

Title: Colapso crítico gravitacional del campo escalar complejo

Abstract: Se presenta el estudio numérico del colapso crítico de un campo escalar complejo acoplado mínimamente a la gravedad. Tomando como dato inicial un pulso gaussiano, dependiendo de su ancho podemos obtener colapso crítico del tipo I o II. En el colapso de tipo I, la solución crítica corresponde a una estrella de bosones inestable en el estado base. Nuestros resultados de las simulaciones pueden ser contrastados con los valores característicos de una estrella de Bosones y su exponente de Lyapunov.

Alejandro Aguilar Nieto

Title: Self interacting scalar field distributions around Schwarzschild black holes

Abstract: Long-lived configurations of massive scalar fields around black holes may form if the coupling between the mass of the scalar field and the mass of the black hole is very small. In this work, we analyze the effect of self-interaction in the distribution of the long-lived cloud surrounding a stationary black hole. We consider both attractive and repulsive self-interactions.

Elías Castellanos (Zoom)

Title: Properties of non-relativistic boson stars

Abstract: In this talk I will explore the possibility that dark matter could be formed by generic scalars or bosons in the form of a Bose-Einstein condensate and also discuss its eventual relation with the so-called boson stars in the non-relativistic regime.

Víctor Manuel Jaramillo

Title: Magnetostatic boson stars

Abstract: We will present solutions to the static axially symmetric Einstein-Maxwell-Klein-Gordon system of equations, describing a compact magnetized object which is electrically neutral. We will describe several properties of such solution, including the torus form of the matter density and the expected dipolar distribution of the magnetic field. A discussion is presented on a case where the gravitational and magnetic fields in the external region are similar to those of magnetars.

Daniel Martínez Carbajal

Title: Estrella de Bosones cargada en la electrodinámica de Born Infeld

Abstract: Desde inicios del siglo XX, algunos físicos no estaban satisfechos con la singularidad de los campos eléctricos en el origen de una carga puntual que experimentalmente tiene un valor finito. Para solucionar este problema se propusieron varias formulaciones de la electrodinámica, entre ellos una versión no lineal de la teoría. Entre los modelos más exitosos se encuentra el modelo de Born e Infeld, en donde se parte de una acción no lineal y se postula un límite en la intensidad del campo.

En particular en esta plática discutiremos los aspectos generales de la electrodinámica de Born-Infeld (BI), así como sus aplicaciones en soluciones de agujeros negros y estrellas de bosones en donde discutiremos el papel que juega el parámetro “b” de BI.

OCTOBER 28

Luis Ureña, Francisco Linares and Osvaldo Téllez

Online material.

CLASS: http://class-code.net, https://github.com/lesgourg/class_public, https://lesgourg.github.io/courses.html, https://usermanual.wiki/Pdf/CLASSMANUAL.1775036913.

MontePython: https://github.com/brinckmann/montepython_public, https://lesgourg.github.io/courses.html.