A5049470751- Black Holes and Theoretical Physics
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Geometry and complex manifolds
- Astronomy and Astrophysical Research
- Quantum Chromodynamics and Particle Interactions
- Computational Physics and Python Applications
- Astrophysical Phenomena and Observations
- Neural Networks and Applications
- Advanced Differential Geometry Research
- Advanced Data Storage Technologies
- Nonlinear Waves and Solitons
- Topological and Geometric Data Analysis
- Model Reduction and Neural Networks
- Advanced Neuroimaging Techniques and Applications
- Geophysics and Gravity Measurements
- Machine Learning and ELM
- Gamma-ray bursts and supernovae
- Scientific Computing and Data Management
- Quantum many-body systems
- Parallel Computing and Optimization Techniques
- Satellite Image Processing and Photogrammetry
Ludwig-Maximilians-Universität München
2018-2024
Stuttgart Observatory
2023
LMU Klinikum
2021-2023
Center for Theoretical Physics
2023
University of Oxford
2015-2018
University of Bonn
2012-2014
University of Cambridge
2009-2011
The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying sky in December 2019, with aim of producing all-sky X-ray source lists and maps an unprecedented depth. Here we present catalogues both point-like extended sources using data acquired first six months survey operations (eRASS1; completed June 2020) over half whose proprietary rights lie German Consortium. We describe observation process, analysis pipelines, characteristics sources. With nearly 930...
Clusters of galaxies can be used as powerful probes to study astrophysical processes on large scales, test theories the growth structure, and constrain cosmological models. The driving science goal SRG/eROSITA All-Sky Survey is assemble a sample X-ray clusters with well-defined selection function determine evolution mass and, hence, parameters. We present here catalog 12 247 optically confirmed galaxy groups detected in 0.2–2.3 keV extended sources 13 116 deg 2 region western Galactic half...
The evolution of the cluster mass function traces growth linear density perturbations, providing valuable insights into structures, nature dark matter, and cosmological parameters governing Universe. primary science goal eROSITA, on board Spectrum Roentgen Gamma (SRG) mission, is to constrain cosmology through function. In this paper, we present a set constraints obtained from 5259 clusters galaxies detected over an area 12791 deg 2 in western Galactic hemisphere eROSITA’s first All-Sky...
Natural (axionic) inflation [1] can accommodate sizeable primordial tensor modes but suffers from the necessity of trans-Planckian variations inflaton field. This problem be solved via mechanism aligned axions [2], where axion spirals down in potential other axions. We elaborate on view recently reported observations BICEP2 collaboration [3].
We address the open question of performing an explicit stabilisation all closed string moduli (including dilaton, complex structure and Kaehler moduli) in fluxed type IIB Calabi-Yau compactifications with chiral matter. Using toric geometry we construct manifolds del Pezzo singularities. D-branes located at such singularities can support Standard Model gauge group matter content. In order to control consider which exhibit a discrete symmetry that reduces effective number moduli. calculate...
Axion-like particles (ALPs) can induce localised oscillatory modulations in the spectra of photon sources passing through astrophysical magnetic fields. Ultra-deep Chandra observations Perseus cluster contain over $5 \times 10^5$ counts from AGN central galaxy NGC1275, and represent a dataset extraordinary quality for ALP searches. We use this to search X-ray spectral irregularities AGN. The absence at O(30%) level allows us place leading constraints on ALP-photon mixing parameter...
A generic feature of string compactifications is the presence many scalar fields, called moduli. Moduli are usually displaced from their post-inflationary minimum during inflation. Their relaxation to could lead production oscillons: localised, long-lived, non-linear excitations fields. Here we discuss under which conditions oscillons can be produced in cosmology and illustrate potential phenomenology with two explicit examples: case an initially volume modulus KKLT scenario a blow-up Kähler...
Abstract Identifying symmetries in data sets is generally difficult, but knowledge about them crucial for efficient handling. Here we present a method how neural networks can be used to identify symmetries. We make extensive use of the structure embedding layer network which allows us whether symmetry and orbits input. To determine continuous or discrete group analyse invariant examples based on rotation groups SO ( n ) unitary SU (2). Further find that this useful classification complete...
A bstract We use machine learning to approximate Calabi-Yau and SU(3)-structure metrics, including for the first time complex structure moduli dependence. Our new methods furthermore improve existing numerical approximations in terms of accuracy speed. Knowing these metrics has numerous applications, ranging from computations crucial aspects effective field theory string compactifications such as canonical normalizations Yukawa couplings, massive spectrum which plays a role swampland...
We analyse soft supersymmetry breaking in type IIB de Sitter string vacua after moduli stabilisation, focussing on models which the Standard Model is sequestered from sources and spectrum of soft-terms hierarchically smaller than gravitino mass m 3/2. Due to this feature, these are compatible with gauge coupling unification TeV scale no cosmological problem. determine influence concrete realisations constructed supersymmetric effective actions. One scenarios provides first study for...
Abstract We argue that accidental approximate scaling symmetries are robust predictions of weakly coupled string vacua, and show their interplay with supersymmetry other (generalised) internal underlies the ubiquitous appearance no‐scale supergravities in low‐energy 4D EFTs. identify 4 nested types supergravities, how leading quantum corrections can break scale invariance while preserving some properties (including non‐supersymmetric flat directions). use these ideas to classify supergravity...
We present the first version of CYJAX, a package for machine learning Calabi-Yau metrics using JAX. It is meant to be accessible both as top-level tool and library modular functions. CYJAX currently centered around algebraic ansatz K\"ahler potential which automatically satisfies K\"ahlerity compatibility on patch overlaps. As now, this implementation limited varieties defined by single defining equation one complex projective space. comment some planned generalizations.
We present deep observations in targeted regions of the string landscape through a combination analytic and dedicated numerical methods. Specifically, we devise an algorithm designed for systematic construction Type IIB flux vacua finite moduli space. Our is universally applicable across Calabi-Yau orientifold compactifications can be used to enumerate region given sufficient computational efforts. As concrete example, apply our methods two-modulus threefold, demonstrating that enumeration...
The detection of the extended X-ray-emission intracluster medium by first SRG/eROSITA All-Sky Survey (eRASS1), combined with optical and near-infrared follow-up, resulted in identification more than 12000 galaxy clusters, yielding precise constraints on cosmological parameters. However, some clusters galaxies can be misclassified as point sources eROSITA's source algorithm due to interplay between point-spread function, shallow depth survey, compact (cool core) X-ray emission, bright active...
Ultra-light axions are hypothetical scalar particles that influence the evolution of large-scale structures Universe. Depending on their mass, they can potentially be part dark matter component Universe, as candidates commonly referred to fuzzy matter. While strong constraints have been established for pure models, more general scenario where ultra-light constitute only a fraction has limited few observational probes. In this work, we use galaxy cluster number counts obtained from first...
Recent advancements in methods used wide-area surveys have demonstrated the reliability of number density galaxy clusters as a viable tool for precision cosmology. Beyond testing current cosmological paradigm, cluster counts can also be to investigate discrepancies currently affecting measurements. In particular, studies based on cosmic shear and other large-scale structure probes routinely find value amplitude fluctuations universe Sh = σ_ (Ω_ m smaller than one inferred from primary...
We initiate a way of generating models by the computer, satisfying both experimental and theoretical constraints. In particular, we present framework which allows generation effective field theories. use Generative Adversarial Networks to generate these examples go beyond known machine. As starting point, apply this idea supersymmetric case, machine knows consistent theories with single generates new such generated potentials find distinct properties, here number minima in scalar potential,...
The most promising MSSM candidates of the heterotic string reveal some distinctive properties. These include gauge-top unification, a specific solution to mu-problem and mirage pattern for gaugino masses. location top- Higgs-multiplets in extra dimensions differs significantly from that other quarks leptons leading characteristic signature suppressed soft breaking terms, reminiscent scheme known as natural supersymmetry.
We explore the possibility that (Bose-Einstein) condensation of scalar fields from string compactifications can lead to long-lived compact objects. Depending on type we find different realisations star-like and solitonic illustrate in framework type~IIB closed moduli heavy microscopic stars with masses order $\mathcal{V}^\alpha M_{\rm Planck}$, $\alpha=1,3/2,5/3$ where $\mathcal{V}$ is volume extra dimensions. Macroscopic objects ultra-light axions are realised $e^{\mathcal{V}^{2/3}}M_{\rm...
We investigate the impact of AGN feedback, on entropy and characteristic temperature measurements galaxy groups detected in SRG/eROSITA's first All-Sky Survey (eRASS1) to shed light characteristics feedback mechanisms. analyze deeper eROSITA observations 1178 eRASS1. divide sample into 271 subsamples extract average thermodynamic properties, including electron density, temperature, at three radii along with integrated by jointly analyzing X-ray images spectra following a Bayesian approach....
Clusters of galaxies can be used as powerful probes to study astrophysical processes on large scales, test theories the growth structure, and constrain cosmological models. The driving science goal SRG/eROSITA All-Sky Survey (eRASS) is assemble a sample X-ray-selected clusters with well-defined selection function determine evolution mass and, hence, parameters. We present here catalog 12247 optically confirmed galaxy groups detected in 0.2-2.3 keV extended X-ray sources 13,116deg$^2$ region...