UNDARK Seminar Series
Quantum Simulators for the Cosmos: From Confining Strings to the Early Universe - Enrique Rico Ortega (CERN-TH)
December 04, 2025
Abstract: The rapid progress of quantum technologies—highlighted by recent Nobel Prizes recognizing advances in controlling quantum matter—is reshaping how we investigate the fundamental laws of nature. In this colloquium, I will introduce the concept of quantum machines: platforms such as quantum computers, analog simulators, and engineered networks of photons or ultracold atoms that process information according to the principles of quantum mechanics. These systems are emerging as powerful tools to emulate physical phenomena that were previously inaccessible to theory or experiment. By bridging quantum information science, tensor network methods, and high-energy physics, this work exemplifies how quantum machines are becoming laboratories for exploring exotic phases of matter, the structure of gauge fields, and the processes that shaped the early cosmos. Together, these advances mark the beginning of a new era in which we can engineer, manipulate, and ultimately understand some aspects of the quantum fabric of the universe.
The Emergence of Dwarf Galaxies, Star Clusters and Something In-between - Justin Read (University of Surrey)
June 26, 2025
Abstract: Over the past five years, numerical simulations of galaxy formation have quietly passed a key milestone. The latest cosmological simulations are now able to resolve the sites of star formation and the impact of individual stellar feedback events. In this talk, I explain how this has led to a new level of realism that makes simulations more predictive. I present the latest results from the "EDGE" simulation project (with a spatial resolution of ~3pc), focussed on modelling the very smallest stellar systems in the Universe. I show how realistic dwarf galaxies and dense star clusters - globular clusters and nuclear star clusters - naturally emerge in EDGE. I present a new semi-empirical tool for galaxy formation, DarkLight, that allows us to scale up the results from a small number of high resolution EDGE simulations to full galaxy populations. And, I present the testable predictions that our EDGE simulations make for new objects that should be found in up-coming surveys. Finally, I conclude with a discussion of where the field is heading next.
Dark Matter and the 511 keV Line: Clues from the Galactic Centre - Pedro de la Torre Luque (Universidad Autónoma de Madrid)
June 19, 2025
Abstract: Measurements of the 511 keV emission reveal the presence of a steady injection of positrons that is very concentrated around the Galactic centre, and whose origin remains unknown. While astrophysical sources do not easily fit the observed morphology and intensity of this excess, MeV dark matter has been proposed as a compelling explanation with interesting consequences. In this seminar, I will introduce the "positron puzzle" and discuss its correlation to other anomalous emissions at the Galactic centre, especially focusing on the observational consequences of the dark matter explanation of the 511 keV excess. Finally, I’ll show how these observations can be used to constrain the properties of asteroid-mass primordial black holes and beyond Standard Model particles, such as sterile neutrinos or axion-like particles.
Latest Neutrino Achievements and Possible Synergies to Science in the IAC - Anatael Cabrera (CNRS / Université Paris-Saclay - IJCLab (Orsay) / LNCA (Chooz))
April 8, 2025
Abstract: The elusiveness of neutrinos is most renowned for their ability to penetrate and traverse vast amounts of matter without disturbance. While this very same property makes neutrino detection one of humanity’s most remarkable achievements, recent and forthcoming advancements in instrumentation continue to enhance our ability to harness neutrino-based information as a fundamental tool. This, in turn, provides unique insights into some of the most essential mysteries of the Universe. For instance, shortly after their discovery in the 1950s, neutrinos offered direct confirmation and deeper understanding of the fundamental fusion processes powering the Sun. Today, they are indispensable to our quest for a comprehensive understanding of Earth’s interior, the depths of the Sun, supernovae, high-energy cosmic ray emissions, and the early Universe’s structure following the Big Bang. Furthermore, neutrinos may play a crucial role in our pursuit of the origins of matter and the search for new physics beyond the Standard Model.
In this colloquium, I will highlight some of the most remarkable achievements in neutrino science to date, as well as emerging advancements that have the potential to complement all other cosmic probes — most notably, those within the IAC’s leadership in this field.
LMC Measures of Complexity: 30 Years Story with Roots at IAC and Many Facets, including Astronomical - Ángel Ricardo Plastino (Universidad Nacional del Noroeste de la Prov. de Buenos Aires (UNNOBA))
February 19, 2025
Abstract: The LMC measure, proposed in 1995 by López-Ruiz, Mancini and Calbet, assigns a quantitative amount of complexity to a discrete probability distribution, or to a continuous probability density. The main idea motivating the LMC measure is the basic intuition, shared by most researchers studying complexity in natural phenomena, according to which systems exhibiting a large amount of order, or a large amount of disorder, have low or vanishing complexity. Consequently, the LMC measure is constructed in such a way that it vanishes in these two extreme cases, and adopts its maximum value for some intermediate regime. The above mentioned “boundary” restrictions, however, are not enough to determine a unique measure of statistical complexity. In fact, researchers have introduced several statistical measures of complexity, akin to the original LMC one, defined as products of information or entropic-like quantities, that also comply with the aforementioned requirements. These measures, which we collectively refer to as “LMC- measures”, have been applied by scientists to the study of diverse problems in Physics and other fields, leading to a research literature of respectable size. In spite of the intriguing results yielded by those investigations, various fundamental issues regarding the LMC measures remain unexplored. In particular, relatively little attention has been paid to identify, and investigate, the kind of dynamical processes governing time-dependent probability densities, that evolve towards densities optimizing the LMC measures, under suitable constraints. Given the remarkable amount of phenomenological applications of the LMC measures to diverse fields, including Astronomy, that have been developed by researchers over the years, it seems timely, thirty years after the LMC proposal, to re-consider some of its conceptual foundations. Our aim is to re-visit these issues, paying special attention to the possible dynamical origins of densities optimizing the LMC measures. In particular, we shall explore the main properties of a family of evolution equations satisfying an H-like theorem based on the LMC measures. We shall present these considerations within the context of other fundamental open questions concerning the LMC measures.
A robust cosmic standard ruler from the cross-correlation of galaxies and dark sirens - Raul Abramo (Universidad de Sao Paulo)
February 13, 2025
Abstract: Supernovae represent the explosive death of a star. There is a small group of core-collapse supernovae whose peak luminosity in the light curve is so high that it cannot be explained by conventional models. Therefore, it is necessary to consider alternative boosting mechanisms to understand their origin. In this talk, I will present the characterization of the largest sample of hydrogen-rich superluminous supernovae (SLSN II) available to date. I will discuss the possible mechanisms responsible for the observed features and the minimum requirements needed to conduct similar analyses using data from the Legacy Survey of Space and Time (LSST) of the Vera C. Rubin Observatory.
Unveiling dark matter halo substructure through N-body cosmological simulations - Alejandra Aguirre-Santaella (Durham University)
February 4, 2025
Abstract: Strong gravitational evidence at galactic, extragalactic and cosmological scales exists to believe that most of the matter in our Universe, i.e. up to ∼85% of the total, is dark and non-baryonic. Yet, this dark matter (DM) has not been directly detected. Some of the most preferred scenarios suggest that DM consists of Weakly Interacting Massive Particles (WIMPs), which interact mostly gravitationally with baryonic matter. There are three complementary techniques to hunt for these WIMPs: production in colliders, direct detection via scattering of Standard Model nuclei, and indirect detection of DM annihilation/decay products. Since all evidence we currently have on DM is astrophysical, indirect searches are the only ones that can provide a means not only to identify the necessary connection between the astrophysical observations and what DM is made of, but also to help unravel the precise DM distribution in the Universe. This talk focuses on shedding light on the nature and distribution of DM paying particular attention to the so-called DM halo substructure or subhaloes. More specifically, we study the characterisation of the DM subhalo population inside a variety of host halos using data from state-of-the-art numerical cosmological simulations, with a focus on Milky Way-like galaxies. The results help to understand not only the DM clustering at small scales but also the role of subhaloes for current and future indirect DM searches.
Dark satellites as cosmological probes and gamma-ray dark matter targets - Miguel Ángel Sánchez Conde (Universidad Autónoma de Madrid/Instituto de Física Teórica)
January 30, 2025
Abstract: A prediction of the standard LCDM cosmological model is that dark matter (DM) halos are teeming with numerous self-bound substructure, or subhalos. At small scales, subhalos may host no stars/gas at all and thus may not have visible astrophysical counterparts. The existence and precise properties of these ‘dark satellites’ represent important probes of the underlying cosmological model. Also, they may play a key role on the search for DM via its annihilation products. In this talk, I will present current numerical work to characterize the subhalo population with unprecedented detail, and will discuss on the importance that dark satellites may have for DM searches with present or future gamma-ray observatories. I will then summarize the recent efforts we made to search for them in gamma-ray data and to set constraints on the nature of the DM particle using these elusive targets.
Dark Matter Detection: From Outer Space to Extreme Environments - Thong T. Q. Nguyen (Oskar Klein Center)
December 17, 2024
Abstract: In this talk, we will explore innovative approaches to dark matter detection, building upon the foundations of conventional methods. We begin with a concise overview of established detection techniques before delving into direct and indirect detection strategies. For indirect detection, we analyze X-ray data from INTEGRAL/SPI and cosmic-ray positron measurements from AMS-02, leveraging these observations to impose stringent constraints on the decay of dark photon dark matter. In the context of direct detection, we highlight the potential of low-threshold detectors for probing boosted dark matter. Finally, at the intersection of indirect and direct detection, we discuss the novel concept of utilizing celestial objects as natural dark matter colliders and detectors, offering a unique avenue to constrain interactions between dark matter and the Standard Model.
The present and future of gravitationally lensed supernovae - Nikki Arendse (Oskar Klein Centre)
November 14, 2024
Abstract: Strongly lensed supernovae are extremely rare and powerful probes that can give insights into high-redshift supernova physics, substructures in massive galaxies, and the expansion rate of the Universe. Currently, the lensed supernova field is at a turning point, as we will go from a handful of present discoveries to several hundreds per year with the advance of the next generation of telescopes. In this talk, I will present the current state of the lensed supernova field and future developments. Beginning with the discovery story of ‘SN Zwicky’, a lensed type Ia supernova found with the Zwicky Transient Facility, I will take you on a visual journey, using beautiful observations to highlight our discoveries about SN Zwicky, its exceptionally light lens galaxy, and implications for stellar microlensing. Finally, we will look ahead at the upcoming Vera Rubin Observatory and how it will help us discover more lensed supernovae and refine our understanding of the Universe’s expansion.
