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Santiago Casas (RWTH Aachen University, TTK)4/24/25, 2:00 PM
In the pursuit of enhancing user interaction with the CLASS (Cosmic Linear Anisotropy Solving System) code, we developed CLApp (CLAss AI-Processing apP), an AI-driven assistant designed to support users in navigating the complexities of cosmological Einstein-Boltzmann solvers.
CLApp assists users in locating parameter names, function names, and modifying code effectively. It also...
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Markus Mosbech (RWTH Aachen)4/24/25, 2:05 PM
OLÉ is a newly released emulator for use in cosmological inference. It features automatic accuracy estimation and online learning with on-the-fly training, allowing it to speed up inference for any cosmological model with no pre-training required. It relies on Gaussian Processes and Principal Component Analysis for efficient data compression and fast evaluation, yielding a speed up of up to...
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Yourong Frank Wang (University of Göttingen)4/24/25, 2:10 PM
Ultralight dark matter (ULDM, also sometimes referred to as Fuzzy DM) is a class of dark matter candidates with masses around $10^{-22}$ eV, leading to wave effects on kiloparsec scales. These wave phenomena offer alternative explanations for small-scale structure and galactic dynamics beyond standard cold dark matter.
In my PhD work, I developed PyUltralight 2 [FWPhys.com/PyUL], a fast and...
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Bernhard Vos Ginés4/24/25, 2:15 PM
Galaxies and neutral hydrogen trace the dark matter distribution. To maximize the extraction of cosmological information from these observables we need to take into account that each survey has its systematic errors that need to be taken into account to not bias our cosmological conclusions. In this work we focus on HI Intensity Mapping surveys. We discuss if the Baryonic Acoustic Oscillations...
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Philipp Klose (Nikhef)4/24/25, 2:50 PM
Thermal effective theories are an important tool for describing the thermodynamics of cosmological phase transitions. Using the Abelian Higgs model as a toy setup, we examine the impact of marginal, higher-dimensional operators that arise at higher orders in the high-temperature expansion used to construct such theories. We demonstrate consistent matching, using field redefinitions to...
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Olivia Bitcon (Institute for Theoretical Physics - University of Münster)4/24/25, 3:10 PM
In the NANOGrav 15-year New Physics analysis (arXiv:2306.16219), a log-uniform prior on $G\mu$ was imposed to determine upper limits on the tension of stable cosmic strings. Here, we examine the prior dependence of this bound through comparison with new upper limits obtained using a uniform prior on $G\mu$. New posterior distributions and upper limits on stable cosmic string tension were...
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Daniel Schmitt4/24/25, 3:30 PM
In the audible axion mechanism, axion-like particles source primordial gravitational waves via their coupling to a dark Abelian gauge field. The original setup, however, relies on a large axion decay constant and coupling to produce sizable signals. In this talk, I will demonstrate that delaying the onset of axion oscillations opens up the testable parameter space and reduces the required...
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Marvin Sipp (Institut für Theoretische Physik, Universität Heidelberg)4/24/25, 3:50 PM
In the past few years, a field-theoretical formulation of non-equilibrium kinetic theory has been developed, based on the path-integral formulation for the Hamiltonian dynamics of an ensemble of classical particles. By specializing it to the self-gravitating case on an expanding background, it can be applied to the problem of cosmic large-scale structure formation.
We present the key steps...
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Asit Dave (University of Bonn)4/24/25, 4:10 PM
The Euclid spectroscopic galaxy survey will identify emission-line galaxies (ELGs) via H$\alpha$ emission within the redshift range $0.9 < z < 1.8$. However, measurement precision is contingent upon both the signal-to-noise ratio of line intensity and the spectrograph's energy resolution. Furthermore, potential line misidentification can occur due to genuine emission lines from different...
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Tim-Leon Klocke (Institute for Theoretical Physics, Heidelberg University)4/24/25, 5:00 PM
Understanding observations of the early and late universe requires studying the evolution of large-scale structures (LSS) in analytic models. A lot of research is concerned with cold dark matter (CDM), but the influence of massive/massless neutrinos, and photons is not insignificant. Therefore, in this talk, a generalized version of kinetic field theory (KFT) is presented by going from a...
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Daniela Grandon (Leiden University)4/24/25, 5:05 PM
The higher-order statistics comprise a set of statistical tools that are designed to capture the non-Gaussianities encoded in the cosmic density field. In weak lensing cosmology, they are implemented to unveil complementary information to the two-point statistics, and to calibrate systematic effects such as baryons, photo-z, etc. In this talk, I will introduce weak lensing higher-order...
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Nicholas Leister (Johannes Gutenberg Universität)4/24/25, 5:10 PM
We discuss the scalar-induced-gravitational-wave (SIGW) signal from primordial black hole (PBH) evaporation. In the monochromatic scenario, a significant signal is generated by the poltergeist mechanism as a result of a sudden transition from matter to radiation dominance. Non-trivial mass distributions affect this mechanism by prolonging the transition period. We show that for realistic mass...
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Christopher Gerlach (Johannes Gutenberg-Universität Mainz)4/24/25, 5:15 PM
While searches for neutrino isocurvature usually constrain a specific linear combination of isocurvature perturbations, this talk focusses on realistic cosmological scenarios giving rise to neutrino isocurvature - mostly in the form of dark radiation. In general both, neutrino and dark matter isocurvature perturbations are generated, whose ratio can be parameterised by a newly introduced...
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Rodrigo Gonzalez Quaglia (University of Groningen)4/24/25, 5:35 PM
Abstract: In this talk I will present our recent work where we studied an extension of the natural inflation model comprising a non-Abelian gauge sector coupled to the axion-inflaton kinetic term. I will show how such non-minimal coupling serves as a source of friction for the rolling inflaton granting sixty or more $e$-folds of accelerated expansion for sub-Planckian values of the axion decay...
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Antonio Junior Iovino (New York University Abu Dhabi)4/24/25, 5:55 PM
Primordial black holes (PBHs) are intriguing astrophysical objects that could shed light on the early universe and offer insights into cosmology and gravitational physics. This presentation provides an overview of PBHs, focusing on their abundance and the associated scalar-induced gravitational waves (SIGWs), which are detectable through pulsar timing arrays (PTAs). A key topic will be the...
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Alica Ela Rogelj (University of Bern, AEC, ITP)4/24/25, 6:15 PM
We assume that at a late stage of inflation, a scalar inflaton field, a thermal plasma, and a spacetime metric coexisted and interacted with each other. We expand them to the linear order around a homogeneous background and combine the perturbations into a set of gauge invariant variables. For the latter we derive evolution equations in the framework of smooth reheating. Having resolved some...
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Juraj Klarić (Univerziteit van Amsterdam, Nikhef, University of Zagreb)4/25/25, 9:00 AM
Hot viscous plasmas unavoidably emit a gravitational wave background, similar to electromagnetic black body radiation.We study the contribution from hidden particles to the diffuse background emitted by the primordial plasma in the early universe.While this contribution can easily dominate over that from Standard Model particles, we find that both are capped by a generic upper bound that makes...
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Cristina Puchades Ibáñez (JGU)4/25/25, 9:20 AM
Previous studies on the production of feebly interacting particles have encountered challenges due to unphysical (negative) interaction rates at soft momenta. We resolve this issue by investigating the thermal production of Axion-Like Particles (ALPs) through freeze-in mechanisms via feeble interactions with U(1) gauge fields, employing the full 1PI-resummed gauge boson propagator. This...
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Valentin Weber (UCLouvain - CP3)4/25/25, 9:40 AM
We search for an excess of electrons and positrons in the interplanetary space from the decays of heavy neutrinos produced in nuclear reactions in the Sun. Using measurements of the electron spectra in the MeV range from the Ulysses and SOHO satellites, we report the strongest direct upper bound to date on the mixing between heavy neutral leptons with MeV masses and electron neutrinos,...
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Richard von Eckardstein (Institute for Theoretical Physics, University of Münster)4/25/25, 10:30 AM
Axion inflation is an extension of the slow-roll paradigm featuring helical gauge-field production with possible consequences for inflationary magnetogenesis, leptogenesis, reheating, and gravitational wave production. I focus on the latter, studying the detectability of gauge-field-induced gravitational waves from axion inflation. For this, I consider two models: the first featuring a...
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David Esmyol (Institute for Theoretical Physics - University of Münster)4/25/25, 10:35 AM
In this talk, I will present results obtained with a new method to infer approximate Bayesian posterior distributions for spectral models of a stochastic gravitational wave background relevant for pulsar timming arrays. To this end we make use of a simple reference model but go beyond the commonly used power-law ansatz by considering the next logical step: a running-power-law (RPL) with a...
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Alexander Ganz4/25/25, 10:40 AM
We find a connection between relativistic Modified Newtonian Dynamics (MOND) theories and (scalar) mimetic gravity. We first demonstrate that any relativistic MOND model featuring a unit-timelike vector field, such as TeVeS or Aether-scalar-tensor theory, can be embedded within a conformal/disformal-invariant framework. Gauge fixing the conformal/disformal symmetry amounts to imposing a...
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Tobias Vičánek Martínez4/25/25, 10:45 AM
The next generation pf radio surveys is going to be transformative for cosmology and other parts of astrophysics. Realistic simulations of radio observations are essential for the design and planning of radio surveys.
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We implement a software for machine learning-assisted simulation of realistic surveys with the Low-Frequency Array (LOFAR), resulting in a synthetic radio sky model and a... -
Ricardo Waibel (Institute for Theoretical Physics, Heidelberg University)4/25/25, 11:05 AM
We study the asymptotic behaviour of the free, cold-dark matter density fluctuation bispectrum in the limit of small separations. From an initially Gaussian random field, we draw phase-space positions of test particles which then propagate along Zel’dovich trajectories. A suitable expansion of the initial momentum auto-correlations of these particles leads to an asymptotic series whose...
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Mathilde Pinon (CEA/Irfu/DPhP)4/25/25, 11:25 AM
Density-split correlation functions, that probe galaxy clustering in different density environments, are an easily interpretable and promising statistics to extract non-Gaussian information from galaxy clustering, as highlighted for instance in the Beyond-2pt mock challenge. While previous analyses have relied on simulation-based models, here we develop a theoretical approach to model these...
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