A5100761090- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- CCD and CMOS Imaging Sensors
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Medical Imaging Techniques and Applications
- GaN-based semiconductor devices and materials
- History and Developments in Astronomy
- Galaxies: Formation, Evolution, Phenomena
- Spectroscopy and Laser Applications
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Neural Networks and Applications
- Silicon Carbide Semiconductor Technologies
- Ga2O3 and related materials
- Advanced Neural Network Applications
- ZnO doping and properties
- Laser Design and Applications
- Advanced Statistical Methods and Models
- Domain Adaptation and Few-Shot Learning
- Laser-Plasma Interactions and Diagnostics
University of California, Berkeley
2019-2024
University of California, San Diego
2024
Physikalisch-Technische Bundesanstalt
2024
Berkeley College
2020-2023
University of Rochester
2023
South China Normal University
2021
Beijing Jiaotong University
2018
University of Oklahoma
2002
Peking University
1999
On 2019 August 14, the Advanced LIGO and Virgo interferometers detected high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that event resulted from a neutron star--black hole (NSBH) merger, or potentially low-mass binary black merger. Due to low false alarm rate precise localization (23 deg$^2$ at 90\%), S190814bv presented community with best opportunity yet directly observe an optical/near-infrared counterpart NSBH To search for potential counterparts, GROWTH...
Abstract We identify the progenitor star of SN 2023ixf in Messier 101 using Keck/NIRC2 adaptive optics imaging and pre-explosion HST/ACS images. The supernova, localized with diffraction spikes high-precision astrometry, unambiguously coincides a candidate mF814W = 24.87 ± 0.05 (AB). Given its reported infrared excess semi-regular variability, we fit time-dependent spectral energy distribution (SED) model dusty red supergiant (RSG) to combined dataset HST optical, ground-based near-infrared,...
Abstract The discovery of a transient kilonova following the gravitational-wave (GW) event GW170817 highlighted critical need for coordinated rapid and wide-field observations, inference, follow-up across electromagnetic spectrum. In southern hemisphere, Dark Energy Camera (DECam) on Blanco 4 m telescope is well suited to this task, as it able cover wide fields quickly while still achieving depths required find kilonovae like one accompanying ∼500 Mpc, binary neutron star (NS) horizon...
Abstract The first two months of the third Advanced LIGO and Virgo observing run (2019 April–May) showed that distant gravitational-wave (GW) events can now be readily detected. Three candidate mergers containing neutron stars (NS) were reported in a span 15 days, all likely located more than 100 Mpc away. However, such as three new NS are to coarsely localized, which highlights importance facilities scheduling systems enable deep observations over hundreds thousands square degrees detect...
ABSTRACT Recent studies show that a universal relation between black hole (BH) growth and stellar mass (M⋆) or star formation rate (SFR) is an oversimplification of BH–galaxy coevolution, morphological structural properties host galaxies must also be considered. Particularly, possible connection BH host-galaxy compactness was identified among star-forming (SF) galaxies. Utilizing ≈6300 massive with I814W < 24 at z 1.2 in the Cosmic Evolution Survey (COSMOS) field, we perform...
Abstract Cosmic ray (CR) identification and replacement are critical components of imaging spectroscopic reduction pipelines involving solid-state detectors. We present deepCR , a deep-learning-based framework for CR subsequent image inpainting based on the predicted mask. To demonstrate effectiveness this framework, we train evaluate models Hubble Space Telescope ( HST ) ACS/WFC images sparse extragalactic fields, globular clusters, resolved galaxies. that at false-positive rate 0.5%,...
Fast and automated inference of binary-lens, single-source (2L1S) microlensing events with sampling-based Bayesian algorithms (e.g., Markov Chain Monte Carlo; MCMC) is challenged on two fronts: high computational cost likelihood evaluations simulation codes, a pathological parameter space where the negative-log-likelihood surface can contain multitude local minima that are narrow deep. Analysis 2L1S usually involves grid searches over some parameters to locate approximate solutions as...
The authors experimentally demonstrate the sympathetic cooling of Th${}^{3+}$ ions, captured from uranium alpha-recoil sources, in a linear Paul trap using laser-cooled ${}^{88}$Sr${}^{+}$ ions. They show efficacy their method via high-resolution laser spectroscopy. This demonstration is an important step enabling use these ions as reference highly accurate nuclear optical clock.
Neural networks (NNs) have been shown to be competitive against state-of-the-art feature engineering and random forest (RF) classification of periodic variable stars. Although previous work utilising NNs has made use periodicity by period folding multiple-cycle time-series into a single cycle -- from time-space phase-space no approach date taken advantage the fact that network predictions should invariant initial phase period-folded sequence. Initial is exogenous physical origin variability...
The offset microlensing degeneracy, recently proposed by Zhang et al. (2022), has been shown to generalize the close-wide and inner-outer caustic degeneracies into a unified regime of magnification degeneracy in interpretation 2-body planetary observations. While expects source trajectory pass equidistant caustics degenerate lens configurations, states that same mathematical expression applies any combination close, wide, resonant topologies, where projected star-planet separations differ an...
We identify the progenitor star of SN 2023ixf in nearby galaxy Messier 101 using Keck/NIRC2 adaptive optics imaging and pre-explosion HST/ACS images. The supernova position, localized with diffraction-spike pattern high precision relative astrometry, unambiguously coincides a single candidate m_F814W=24.96(-0.04)(+0.05). Forced photometry further recovers 2-sigma detections F673N F675W bands imposes robust flux limits on bluer bands. Given reported infrared excess semi-regular variability...
Abstract deepCR is a deep-learning-based cosmic-ray (CR) rejection framework originally presented by Zhang & Bloom. The original approach requires dedicated training set that consists of multiple frames the same fields, enabling automatic CR labeling through comparison with their median coadds. Here, we present novel circumvents need for set, but instead utilizes dark and science images requiring removal themselves. During training, CRs in are added to images, which network then trained...
Shock breakout emission is light that arises when a shockwave, generated by core-collapse explosion of massive star, passes through its outer envelope. Hitherto, the earliest detection such signal was at several hours after explosion, though few others had been reported. The temporal evolution early curves should reveal insights into shock propagation, including asymmetry and environment in vicinity, but this has hampered lack multiwavelength observations. Here we report instant multiband...
Under the perturbative picture of planetary microlensing, planet is considered to act as a uniform-shear Chang-Refsdal lens on one two images produced by host star that comes close angular Einstein radius planet, leaving other image unaffected. However, this approximation only valid for isolated caustics and breaks down in resonant regime. Recently, planetary-caustic degeneracy arising from above formalism found generalize regime central caustics, indicating may have been under-explored...
Astronomical imaging and spectroscopy data are frequently corrupted by "cosmic rays" (CR) which high energy charged particles that instrumental, terrestrial, or cosmic in origin.When such pass through solid state detectors, as coupled devices (CCDs), they create excess flux the pixels hit lead to artifacts images.These must be identified either masked replaced, before further scientific analysis could done on image data.It is straightforward identify these when multiple exposures of same...
Terrestrial planets born beyond 1-3 AU have been theorized to avoid being engulfed during the red-giant phases of their host stars. Nevertheless, only a few gas-giant observed around white dwarfs (WDs) -- end product left behind by red giant. Here we report on evidence that lens system produced microlensing event KMT-2020-BLG-0414 is composed WD orbited an Earth-mass planet and brown dwarf (BD) companion, as shown non-detection flux using Keck Adaptive Optics (AO). From orbital motion...
Hyperfine spectra of /sup 127/I/sub 2/ near 532 nm have been studied via modulation transfer spectroscopy using a self-made, diode-pumped, intracavity-doubled Nd:YVO/sub 4/-KTP standing wave laser. Several new rovibrational transitions, which are beyond the range nine hyperfine components that were recommended recently at Ninth CCDM as optical frequency standards, observed and assigned.