A5070419829- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Calibration and Measurement Techniques
- Statistical and numerical algorithms
- Distributed Control Multi-Agent Systems
- Reinforcement Learning in Robotics
- Smart Grid Energy Management
- Atomic and Subatomic Physics Research
- Gaussian Processes and Bayesian Inference
- Optical Coherence Tomography Applications
- Geochemistry and Geologic Mapping
- Atmospheric Ozone and Climate
- Geophysics and Gravity Measurements
Lawrence Livermore National Laboratory
2015-2024
Space Science Institute
2024
University of California, Davis
2012-2015
Anglo-Norman Text Society
1990
Ono Pharmaceutical (United States)
1990
National Museum Wales
1990
British Library
1990
University College Dublin
1990
Case Western Reserve University
1990
United States Geological Survey
1972
(Abridged) We describe here the most ambitious survey currently planned in optical, Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST have unique capability faint time domain. The design is driven four main themes: probing dark energy matter, taking an inventory Solar System, exploring transient optical sky, mapping Milky Way. wide-field ground-based system sited at Cerro Pach\'{o}n northern Chile. telescope 8.4 m...
We present deep LOFAR observations between 120-181 MHz of the "Toothbrush" (RX J0603.3+4214), a cluster that contains one brightest radio relic sources known. Our exploit new and novel calibration scheme to probe 10 times deeper than any previous study in this relatively unexplored part spectrum. The observations, when combined with VLA, GMRT, Chandra X-ray data, provide information about nature merger shocks their role re-accelerating relativistic particles. derive spectral index $\alpha =...
We present first results from the third GRavitational lEnsing Accuracy Testing (GREAT3) challenge, in a sequence of challenges for testing methods inferring weak gravitational lensing shear distortions simulated galaxy images. GREAT3 was divided into experiments to test three specific questions, and included space- ground-based data with constant or cosmologically varying fields. The simplest (control) experiment parametric galaxies realistic distribution signal-to-noise, size, ellipticity,...
ABSTRACT LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of low-frequency sky. At same time also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images challenging due presence direction-dependent calibration errors, caused by imperfect knowledge station beam shapes ionosphere. Furthermore, large data volume clock errors...
In an influential recent paper, Harvey et al (2015) derive upper limit to the self-interaction cross section of dark matter ($\sigma_{\rm DM} < 0.47$ cm$^2$/g at 95\% confidence) by averaging matter-galaxy offsets in a sample merging galaxy clusters. Using much more comprehensive data on same clusters, we identify several substantial errors their offset measurements. Correcting these relaxes $\sigma_{\rm DM}$ $\lesssim 2$ cm$^2$/g, following prescription for relating sections simple solid...
Abstract Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both extremely distant intrinsically faint populations. We present here candidate high-redshift galaxies from Reionization Lensing Cluster Survey (RELICS), Hubble Spitzer Space Telescope survey 41 massive spanning an area ≈200 arcmin 2 . These were selected to be excellent lenses, we find similar sample sizes magnitude distributions as And Supernova with (CLASH). discover...
We present DLSCL J0916.2+2951 (z=0.53), a newly discovered major cluster merger in which the collisional gas has become dissociated from collisionless galaxies and dark matter. identified using optical weak lensing observations as part of Deep Lens Survey. Our follow-up with Keck, Subaru, Hubble Space Telescope, Chandra show that is dissociative constrain matter self-interaction cross-section {\sigma}_{DM}m_{DM}^{-1}\leq7 cm^2g^{-1}. The system observed at least 0.7\pm0.2 Gyr since first...
Abstract We report L-band VLA observations of 1RXS J0603.3+4214, a cluster that hosts bright radio relic, known as the Toothbrush, and an elongated giant halo. These new allow us to study surface brightness distribution down 1 arcsec resolution with very high sensitivity. Our images provide unprecedented detailed view revealing enigmatic filamentary structures. To spectral index distribution, we complement our analysis published LOFAR GMRT observations. The “brush” Toothbrush shows prominent...
The most distant galaxies known are at z~10-11, observed 400-500 Myr after the Big Bang. few z~10-11 candidates discovered to date have been exceptionally small- barely resolved, if all, by Hubble Space Telescope. Here we present discovery of SPT0615-JD, a fortuitous z~10 (z_phot=9.9+/-0.6) galaxy candidate stretched into an arc over ~2.5" effects strong gravitational lensing. Discovered in Reionization Lensing Cluster Survey (RELICS) Treasury program and companion S-RELICS Spitzer program,...
Abstract Primordial black holes (PBHs) could explain some fraction of dark matter and shed light on many areas early-Universe physics. Despite over half a century research interest, PBH population has so far eluded detection. The most competitive constraints the comprised PBHs ( f DM ) in (10 −9 –10) M ⊙ mass ranges come from photometric microlensing bound ≲ 10 −2 –10 −1 . With advent Roman Space Telescope with its submilliarcsecond astrometric capabilities planned Galactic Bulge Time Domain...
Abstract From the formation mechanisms of stars and compact objects to nuclear physics, modern astronomy frequently leverages surveys understand populations answer fundamental questions. The population dark isolated in Galaxy contains critical information related many these topics, but is only practically accessible via gravitational microlensing. However, photometric microlensing observables are degenerate for different types lenses, one can seldom classify an event as involving either a...
CIZA J2242.8+5301 (`Sausage') and 1RXS J0603.3+4213 (`Toothbrush') are two low-redshift ($z\sim0.2$), massive ($\sim2\times10^{15}M_\odot$), post-core passage merging clusters, which host shock waves traced by diffuse radio emission. To study their star-formation properties, we uniformly survey the `Sausage' `Toothbrush' clusters in broad narrow band filters select a sample of $201$ $463$ line emitters, down to rest-frame equivalent width ($13${\AA}). We robustly separate between H$\alpha$...
The galaxy cluster CIZA J2242.8+5301 at z = 0.19 is a merging system with prominent (∼2 Mpc long) radio relic, which together the morphology of X-ray emission provides strong evidence for violent collision along north–south axis. We present our constraints on dark matter distribution this unusual using Subaru and Canada–France–Hawaii Telescope imaging data. Measuring high signal-to-noise ratio lensing signal from potentially challenging task because its proximity to Milky Way plane (|b| ∼...
Cluster mergers may play a fundamental role in the formation and evolution of cluster galaxies. Stroe et al. revealed unexpected overdensities candidate Hα emitters near ∼1-Mpc-wide shock fronts massive (∼2 × 1015 M⊙) 'Sausage' merging cluster, CIZA J2242.8+5301. We used Keck/Deep Imaging Multi-Object Spectrograph William Herschel Telescope/AutoFib2+WYFFOS to confirm 83 around cluster. find that star-forming galaxies hottest X-ray gas and/or subcores (away from fronts) show high [S...
ABSTRACT Using overlapping fields with space-based Hubble Space Telescope and ground-based Subaru imaging we identify a population of blended galaxies that are to such large degree they detected as single objects in the monochromatic imaging, which label “ambiguous blends.” For deep data, depth targeted Large Synoptic Survey (LSST), ambiguous blend is both (∼14%) has distribution ellipticities different from unblended way will likely be important for weak lensing measurements. Most notably,...
Merging galaxy clusters have become one of the most important probes dark matter, providing evidence for matter over modified gravity and even constraints on self-interaction cross-section. To properly constrain cross-section it is necessary to understand dynamics merger, as inferred a function both velocity collision observed time since collision. While best understanding merging system comes from N-body simulations, these are computationally intensive often explore only limited volume...
Abstract To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA Chandra observations of HST Frontier Fields cluster MACS J0717.5+3745 . The image shows a complex event, with at least four belonging to different merging subclusters. Northwest cluster, ∼0.7 Mpc from center, there is ram-pressure-stripped core that appears have traversed densest parts after entering intracluster medium (ICM) direction filament southeast. We...
Abstract Golovich et al. present an optical imaging and spectroscopic survey of 29 radio relic merging galaxy clusters. In this paper, we study to identify substructure quantify the dynamics mergers. Using a combined photometric approach, minimum number substructures in each system describe populations estimate line-of-sight velocity difference between likely subclusters. We find that components mergers are typically small compared with maximum 3D relative (usually <1000 km s −1 often...
Abstract We present a new Milky Way microlensing simulation code, dubbed PopSyCLE (Population Synthesis for Compact object Lensing Events). is the first resolved to include compact distribution derived from numerical supernova explosion models and both astrometric photometric effects. demonstrate capabilities of by investigating optimal way find black holes (BHs) with microlensing. Candidate BHs have typically been selected wide-field surveys, such as OGLE, selecting events long Einstein...
ABSTRACT We analyse 1602 microlensing events found in the VISTA Variables Via Lactea (VVV) near-infrared (NIR) survey data. obtain spatially resolved, efficiency-corrected time-scale distributions across Galactic bulge (|ℓ| &lt; 10°, |b| 5°), using a Bayesian hierarchical model. Spatially resolved peaks and means of distributions, along with their marginal strips longitude latitude, are agreement at 1σ level predictions based on Besançon model Galaxy. find that event time-scales central...
Abstract There are expected to be millions of isolated black holes in the galaxy resulting from deaths massive stars. Measuring abundance and properties this remnant population would shed light on end stages stellar evolution paths hole systems. Detecting is currently only possible via gravitational microlensing, which has so far yielded one definitive detection. The difficulty finding microlensing lies having choose a small subset events, based characteristics their curves, allocate...
Diffuse radio emission in the form of halos and relics has been found a number merging galaxy clusters. These structures indicate that shock turbulence associated with merger accelerate electrons to relativistic energies. We report discovery relic + halo system PSZ1 G108.18-11.53 (z=0.335). This cluster hosts second most powerful double ever discovered. observed Giant Meterwave Radio Telescope (GMRT) Westerbork Synthesis (WSRT). obtained maps at 147, 323, 607 1380 MHz. also Keck telescope,...