A5046058668- Galaxies: Formation, Evolution, Phenomena
- Seismic Waves and Analysis
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Earthquake Detection and Analysis
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Generative Adversarial Networks and Image Synthesis
- Astronomy and Astrophysical Research
- Seismic Imaging and Inversion Techniques
- Seismology and Earthquake Studies
- Pulsars and Gravitational Waves Research
- Time Series Analysis and Forecasting
- Advanced Data Storage Technologies
- Traffic Prediction and Management Techniques
- Nonlinear Dynamics and Pattern Formation
- Geophysical Methods and Applications
- Gamma-ray bursts and supernovae
- Model Reduction and Neural Networks
- Geophysics and Gravity Measurements
- Machine Learning and Data Classification
- Neural Networks and Applications
- Simulation Techniques and Applications
ETH Zurich
2024
Lawrence Berkeley National Laboratory
2020-2022
University of California, Berkeley
2017-2022
New York University
2022
Twinleaf (United States)
2022
University of Delaware
2022
Helmholtz Institute Mainz
2022
UNSW Sydney
2015-2018
University of Chile
2012
Observations of the redshift z = 7.085 quasar J1120+0641 are used to search for variations fine structure constant, α, over range 5.5 7.1. at 7.1 probe physics universe only 0.8 billion years old. These most distant direct measurements α date and first using a near-IR spectrograph. A new AI analysis method is employed. Four from x-shooter spectrograph on Very Large Telescope (VLT) constrain changes in relative terrestrial value (α0). The weighted mean electromagnetic force this location...
Abstract Ultralight bosons such as axion-like particles are viable candidates for dark matter. They can form stable, macroscopic field configurations in the of topological defects that could concentrate matter density into many distinct, compact spatial regions small compared with Galaxy but much larger than Earth. Here we report results search transient signals from domain walls by using global network optical magnetometers exotic (GNOME) physics searches. We data, consisting correlated...
The primordial deuterium abundance is an important tracer of the fundamental physics taking place during big bang nucleosynthesis. It can be determined from absorption features along line sight to distant quasars. quasar PKS 1937−1009 contains two absorptions systems that have been used measure abundance, lower redshift one being at zabs = 3.256. New observations this absorber are a substantially higher signal-to-noise ratio and thus permit significantly more robust estimate leading D i/H i...
The primordial deuterium abundance probes fundamental physics during the Big Bang Nucleosynthesis and can be used to infer cosmological parameters. Observationally, measured using absorbing clouds along lines of sight distant quasars. Observations quasar PKS1937--101 contain two absorbers for which has previously been determined. Here we focus on higher redshift one at $z_{abs} = 3.572$. We present new observations with significantly increased signal-to-noise ratio enable a far more precise...
The spectrum of the zem = 2.63 quasar Q1009+2956 has been observed extensively on Keck telescope. Lyman limit absorption system zabs 2.504 was previously used to measure D/H by Burles & Tytler using a with signal noise (S/N) approximately 60 per pixel in continuum near Ly α at 2.504. larger data set now available combines form an exceptionally high S/N spectrum, around 147 pixel. Several heavy element lines are detected this system, providing strong constraints kinematic structure. We...
We report the detection of neutral deuterium in low-metallicity damped Lyman-α system at zabs = 2.621 towards quasar CTQ 247. Using a high signal-to-noise and spectral resolution (R 60 000) spectrum from Very Large Telescope Ultraviolet Visual Echelle Spectrograph, we precisely measure deuterium-to-oxygen ratio log N(D i)/N(O i) 0.74 ± 0.04, as well overall oxygen abundance, N(O i)/N(H −5.30 0.10 (or equivalently [O/H] −1.99 with respect to solar value). Assuming uniform metallicity...
The Global Network of Optical Magnetometers to search for Exotic physics (GNOME) is a network geographically separated, time-synchronized, optically pumped atomic magnetometers that being used correlated transient signals heralding exotic physics. GNOME sensitive nuclear- and electron-spin couplings fields from astrophysical sources such as compact dark-matter objects (for example, axion stars domain walls). Properties the sensors sensitivity, bandwidth, noise characteristics are studied in...
The gravitational potential phi = GM/Rc^2 at the surface of white dwarf G191-B2B is 10,000 times stronger than that Earth's surface. Numerous photospheric absorption features are detected, making this a suitable environment to test theories in which fundamental constants depend on gravity. We have measured fine structure constant, alpha, surface, used newly calibrated Hubble Space Telescope STIS spectrum G191-B2B, two new independent sets laboratory Fe V wavelengths, and atomic calculations...
Spectra observed with the Ultraviolet and Visual Echelle Spectrograph on European Southern Observatory's VLT exhibit long-range wavelength distortions. These distortions impose a systematic error high-precision measurements of fine-structure constant, α, derived from intervening quasar absorption systems. If distortion is modelled using model that too simplistic, resulting bias in Δα/α away true value can be larger than statistical uncertainty α measurement. effect ignored altogether, same...
Moving loads such as cars and trains are very useful sources of seismic waves, which can be analyzed to retrieve information on the velocity subsurface materials using techniques ambient noise seismology. This is valuable for a variety applications geotechnical characterization near-surface, hazard evaluation, groundwater monitoring. However, processes converge quickly, data segments with appropriate energy should selected. Distributed Acoustic Sensing (DAS) novel sensing technique that...
The zabs = 2.504 Lyman Limit absorption system (LLS) towards Q1009+2956 has previously been used to estimate the primordial deuterium abundance. Since initial measurement by Burles & Tytler [1], this quasar observed extensively with Keck telescope, providing a substantial increase in signal-to-noise (from 60 147 at continuum level of Ly-α 2.504). We explore set different models for and find that feature is contaminated from low column density HI cloud. This significantly limits precision...
Hot white dwarf stars are the ideal probe for a relationship between fine-structure constant and strong gravitational fields, providing us with an opportunity direct observational test. We study sample of hot stars, combining far-UV spectroscopic observations, atomic physics, atmospheric modelling fundamental in search variation fine structure constant. This manifests as shifts observed wavelengths absorption lines, such quadruply ionized iron (FeV) nickel (NiV), when compared to laboratory...
Abstract Results are reported from the first full-scale search for transient signals exotic fields of astrophysical origin using data a newly constructed Earth-scale detector: Global Network Optical Magnetometers Exotic physics searches (GNOME). Data collected by GNOME consist correlated measurements optical atomic magnetometers located in laboratories all over world. searched patterns propagating through network consistent with composed ultralight bosons such as axion-like particles (ALPs)....
Abstract. The magnetic signature of an urban environment is investigated using a geographically distributed network fluxgate magnetometers deployed in and around Berkeley, California. system hardware software are described initial operations the reported. sensors measure vector fields at 3960 Hz sample rate sensitive to 0.1 nT/Hz. Data from individual stations synchronized ±120 µs global positioning (GPS) computer clocks automatically uploaded central server. We present observations...
We present a comparative analysis of urban magnetic fields between two American cities: Berkeley (California) and Brooklyn Borough New York City (New York). Our uses data taken over four-week period during which field were continuously recorded using fluxgate magnetometer with 70 pT/Hz noise. identified significant differences in the signatures. In particular, we noticed that reaches near-zero activity at night, whereas continues nighttime. also auxiliary measurements acquired...
Abstract The Generative Adversarial Network (GAN) is a powerful and flexible tool that can generate high-fidelity synthesized data by learning. It has seen many applications in simulating events High Energy Physics (HEP), including detector responses physics events. However, training GANs notoriously hard optimizing their hyperparameters even more so. normally requires trial-and-error attempts to force stable reach reasonable fidelity. Significant tuning work be done achieve the accuracy...
We present a new software, HYPPO, that enables the automatic tuning of hyperparameters various deep learning (DL) models. Unlike other hyperparameter optimization (HPO) methods, HYPPO uses adaptive surrogate models and directly accounts for uncertainty in model predictions to find accurate reliable make robust predictions. Using asynchronous nested parallelism, we are able significantly alleviate computational burden training complex architectures quantifying uncertainty. is implemented...
Observations of the redshift z=7.085 quasar J1120+0641 have been used to search for variations fine structure constant, alpha, over range 5.5 7.1. at z=7.1 probe physics universe when it was only 0.8 billion years old. These are most distant direct measurements alpha date and first made with a near-IR spectrograph. A new AI analysis method has employed. Four from X-SHOOTER spectrograph on European Southern Observatory's Very Large Telescope (VLT) directly constrain any changes in relative...
Many experimental techniques aim at determining the energy landscape of a system given and compare it to model Hamiltonian. This governs system's evolution in absence dissipation. Here, we theoretically propose experimentally demonstrate method measure without knowing its functional form. A crucial ingredient for our is presence dissipation, which enables sampling over large area phase space through ringdown-type measurements, overcoming main limitation previous techniques. We apply...
In topology, one averages over local geometrical details to reveal robust global features. This approach proves crucial for understanding quantized bulk transport and exotic boundary effects of linear wave propagation in (meta-)materials. Moving beyond Hamiltonian systems, the study topology physics strives characterize open (non-Hermitian) interacting systems. Here, we establish a framework topological classification driven-dissipative nonlinear Specifically, define graph index Floquet...
Deep Learning approaches for real, large, and complex scientific data sets can be very challenging to design. In this work, we present a complete search finely-tuned efficiently scaled deep learning classifier identify usable energy from seismic acquired using Distributed Acoustic Sensing (DAS). While only subset of labeled images during training, were able suitable models that accurately generalized unknown signal patterns. We show by 16 times more GPUs, increase the training speed than two...
The detection of neutral deuterium in the low-metallicity damped Lyman-{\alpha} system at zabs = 2.621 towards quasar CTQ247 is reported. Using a high signal-to-noise and spectral resolution (R 60000) spectrum from Very Large Telescope Ultraviolet Visual Echelle Spectrograph, we precisely measure deuterium-to-oxygen ratio log N(DI)/N(OI) 0.74+/-0.04, as well overall oxygen abundance, N(OI)/N(HI)=-5.29+/-0.10 (or equivalently [O/H]=-1.99+/-0.10 with respect to solar value). Assuming uniform...