W. C. Wester
A5047671618- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Neutrino Physics Research
- Computational Physics and Python Applications
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Medical Imaging Techniques and Applications
- Astro and Planetary Science
- Radiation Detection and Scintillator Technologies
- Black Holes and Theoretical Physics
- Adaptive optics and wavefront sensing
- Radiation Effects in Electronics
- Astrophysical Phenomena and Observations
Fermi National Accelerator Laboratory
2015-2024
Ludwig-Maximilians-Universität München
2024
Lancaster University
2024
Centre National de la Recherche Scientifique
2024
American Public University System
2024
Vanderbilt Health
2024
Aix-Marseille Université
2024
Austin Peay State University
2024
University of Zurich
2024
Stanford University
2024
We present UV, optical, and NIR photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced LIGO/Virgo, binary neutron star merger GW170817. Our data set extends discovery optical at $0.47$ days $18.5$ post-merger, includes observations with Dark Energy Camera (DECam), Gemini-South/FLAMINGOS-2 (GS/F2), {\it Hubble Space Telescope} ({\it HST}). The spectral energy distribution (SED) inferred this $0.6$ is well described by blackbody model $T\approx 8300$...
This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 μeV. The excludes range of axion-photon couplings predicted by plausible models invisible axion. unprecedented sensitivity is achieved operating large-volume at subkelvin temperatures, thereby reducing thermal noise as well excess ultralow-noise superconducting quantum interference device amplifier used signal power readout. Ongoing searches will provide nearly definitive tests...
Abstract We present the Dark Energy Camera (DECam) discovery of optical counterpart first binary neutron star merger detected through gravitational-wave emission, GW170817. Our observations commenced 10.5 hr post-merger, as soon localization region became accessible from Chile. imaged 70 deg 2 in i and z bands, covering 93% initial integrated probability, to a depth necessary identify likely counterparts (e.g., kilonova). At 11.4 post-merger we bright transient located nucleus NGC 4993 at...
We report the discovery of eight new ultra-faint dwarf galaxy candidates in second year optical imaging data from Dark Energy Survey (DES). Six these are detected at high confidence, while two lower-confidence identified regions non-uniform survey coverage. The stellar systems found by three independent automated search techniques and as overdensities stars, consistent with isochrone luminosity function an old metal-poor simple population. faint (Mv > -4.7 mag) span a range physical sizes...
We report the discovery of eight new Milky Way companions in optical imaging data collected during first year Dark Energy Survey (DES). Each system is identified as a statistically significant over-density individual stars consistent with expected isochrone and luminosity function an old metal-poor stellar population. The objects span wide range absolute magnitudes (MV from to ), physical sizes (), heliocentric distances (). Based on low surface brightnesses, large sizes, and/or...
This Letter reports on a cavity haloscope search for dark matter axions in the Galactic halo mass range 2.81-3.31 μeV. utilizes combination of low-noise Josephson parametric amplifier and large-cavity to achieve unprecedented sensitivity across this range. excludes full axion-photon coupling values predicted benchmark models invisible axion that solve strong CP problem quantum chromodynamics.
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO look for axions or axion-like particles (ALPs) originating in the Sun via Primakoff conversion of solar plasma photons. In terms signal-to-noise ratio, about 4–5 orders magnitude more sensitive than CAST, currently most powerful helioscope, reaching sensitivity to axion-photon couplings down few × 10−12 GeV−1 and thus probing large fraction unexplored ALP parameter space....
We combine Dark Energy Survey Year 1 clustering and weak lensing data with Baryon Acoustic Oscillations (BAO) Big Bang Nucleosynthesis (BBN) experiments to constrain the Hubble constant. Assuming a flat $\Lambda$CDM model minimal neutrino mass ($\sum m_\nu = 0.06$ eV) we find $H_0=67.2^{+1.2}_{-1.0}$ km/s/Mpc (68% CL). This result is completely independent of constant measurements based on distance ladder, Cosmic Microwave Background (CMB) anisotropies (both temperature polarization), strong...
We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties dark matter (DM). This analysis fully incorporates inhomogeneities in spatial distribution and detectability MW satellites marginalizes over uncertainties mapping between DM halos, system, disruption subhalos by disk. Our results are consistent with cold, collisionless paradigm yield strongest cosmological constraints date on particle models warm, interacting, fuzzy matter. At 95%...
We introduce redMaGiC, an automated algorithm for selecting Luminous Red Galaxies (LRGs). The was specifically developed to minimize photometric redshift uncertainties in large-scale structure studies. redMaGiC achieves this by self-training the color-cuts necessary produce a luminosity-thresholded LRG sample of constant comoving density. demonstrate that photozs are very nearly as accurate best machine-learning based methods, yet they require minimal spectroscopic training, do not suffer...
We describe the Dark Energy Survey (DES) photometric data set assembled from first three years of science operations to support DES Year 3 cosmology analyses, and provide usage notes aimed at broad astrophysics community. Y3 Gold improves on previous releases DES, Y1 Data Release 1 (DES DR1), presenting an expanded curated that incorporates algorithmic developments in image detrending processing, calibration, object classification. comprises nearly 5000 square degrees grizY imaging south...
We report the first results of GammeV experiment, a search for milli-eV mass particles with axionlike couplings to two photons. The is performed using "light shining through wall" technique where incident photons oscillate into new weakly interacting that are able pass wall and subsequently regenerate back detectable oscillation baseline apparatus variable, thus allowing probes different values particle mass. find no excess events above background constrain two-photon possible scalar...
Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark each their own beautiful structure, distinct particles, and forces. This review summarizes physics motivation sectors exciting opportunities experimental exploration. It is summary Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" Community...
Abstract We present Magellan /IMACS spectroscopy of the recently discovered Milky Way satellite Eridanus II (Eri II). identify 28 member stars in Eri II, from which we measure a systemic radial velocity and dispersion . Assuming that is dispersion-supported system dynamical equilibrium, derive mass within half-light radius , indicating mass-to-light ratio / confirming it dark matter-dominated dwarf galaxy. From equivalent width measurements Ca triplet lines 16 red giant stars, mean...
A search for sub-GeV dark matter produced from collisions of the Fermilab 8 GeV Booster protons with a steel beam dump was performed by MiniBooNE-DM Collaboration using data $1.86\ifmmode\times\else\texttimes\fi{}{10}^{20}$ on target in dedicated run. The MiniBooNE detector, consisting 818 tons mineral oil and located 490 meters downstream dump, is sensitive to variety initiated scattering reactions. Three interactions are considered this analysis: elastic off nucleons, inelastic neutral...
We describe an algorithm for identifying point-source transients and moving objects on reference-subtracted optical images containing artifacts of processing instrumentation. The makes use the supervised machine learning technique known as Random Forest. present results from its in Dark Energy Survey Supernova program (DES-SN), where it was trained using a sample 898,963 signal background events generated by transient detection pipeline. After reprocessing data collected during first DES-SN...
The μeV axion is a well-motivated extension to the standard model. Axion Dark Matter eXperiment (ADMX) collaboration seeks discover this particle by looking for resonant conversion of dark-matter axions microwave photons in strong magnetic field. In Letter, we report results from pathfinder experiment, ADMX "Sidecar," which designed pave way future, higher mass, searches. This testbed experiment lives inside and operates tandem with main experiment. Sidecar excludes masses three widely...
Abstract We present a multi-messenger measurement of the Hubble constant H 0 using binary–black-hole merger GW170814 as standard siren, combined with photometric redshift catalog from Dark Energy Survey (DES). The luminosity distance is obtained gravitational wave signal detected by Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and information provided DES Year 3 data. Black hole mergers such are expected to lack bright...
The Dark Energy Survey (DES) is a five-year optical imaging campaign with the goal of understanding origin cosmic acceleration. DES performs 5000 square degree survey southern sky in five bands (g,r,i,z,Y) to depth ~24th magnitude. Contemporaneously, deep, time-domain four (g,r,i,z) over 27 degrees. exposures are processed nightly an evolving data reduction pipeline and evaluated for image quality determine if they need be retaken. Difference transient source detection also performed time...
We cross-match galaxy cluster candidates selected via their Sunyaev–Zel'dovich effect (SZE) signatures in 129.1 deg2 of the South Pole Telescope 2500d SPT-SZ survey with optically identified clusters from Dark Energy Survey science verification data. identify 25 between 0.1 ≲ z 0.8 union and redMaPPer (RM) samples. RM is an optical finding algorithm that also returns a richness estimate for each cluster. model λ-mass relation following function 〈ln λ|M500〉 ∝ Bλln M500 + Cλln E(z) use masses...
We present the discovery and spectroscopic confirmation with European Southern Observatory New Technology Telescope (NTT) Gemini South telescopes of eight new, rediscovery two previously known, 6.0 < z 6.5 quasars zAB 21.0. These were photometrically selected without any morphological criteria from 1533 deg2 using spectral energy distribution (SED) model fitting to photometric data Dark Energy Survey (g, r, i, z, Y), VISTA Hemisphere (J, H, K) Wide-field Infrared Explorer (W1, W2). The...
We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on spectra 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity dispersion . The mass-to-light ratio within its half-light radius is , demonstrating that it strongly dark matter-dominated system. Despite spatial proximity to Magellanic Clouds, radial differs LMC SMC by 199 83...
Abstract We perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey and 3 Year Dark Energy imaging, which provide light curves spanning more than 15 years. identified ∼1000 EVQs with maximum change g- band magnitude of 1 mag over this period, about 10% all searched. The have L bol ∼ 10 45 –10 47 erg s −1 / Edd 0.01–1. Accounting selection effects, we estimate an intrinsic EVQ fraction ∼30%–50% among baseline ∼15 yr. performed...