R. L. White
A5032745475- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- Astro and Planetary Science
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- Advanced Data Storage Technologies
- Advanced Data Compression Techniques
- Algorithms and Data Compression
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- GNSS positioning and interference
- Distributed and Parallel Computing Systems
Levine Cancer Institute
2024-2025
Carolinas Medical Center
2025
Space Telescope Science Institute
2015-2024
The George Institute for Global Health
2021
The University of Sydney
2021
Cardiff and Vale University Health Board
2019
University of Missouri
2016
Columbia Orthopaedic Group
2016
Academy of Nutrition and Dietetics
2015
University of North Carolina at Chapel Hill
2012
view Abstract Citations (2408) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The FIRST Survey: Faint Images of the Radio Sky at Twenty Centimeters Becker, Robert H. ; White, Richard L. Helfand, David J. survey to produce centimeters is now underway using NRAO Very Large Array. We describe here scientific motivation for a large-area sky radio frequencies which has sensitivity and angular resolution comparable Palomar Observatory Survey, we...
We study the evolution of ionization state IGM at end reionization epoch using spectra a sample nineteen quasars 5.745.7: optical depth changes from tau ~ (1+z)^{4.3} to (1+z)^{>11}, and average length dark gaps with tau>3.5 increases <10 >80 comoving Mpc. The dispersion properties along different lines sight also rapidly, implying fluctuations by factor >4 in UV background z>6, when mean free path photons is comparable correlation galaxies. shows most dramatic increase...
Pan-STARRS1 has carried out a set of distinct synoptic imaging sky surveys including the $3π$ Steradian Survey and Medium Deep in 5 bands ($grizy_{P1}$). The mean 5$σ$ point source limiting sensitivities stacked 3$π$ $grizy_{P1}$ are (23.3, 23.2, 23.1, 22.3, 21.4) respectively. upper bound on systematic uncertainty photometric calibration across is 7-12 millimag depending bandpass. astrometric using Gaia frame comes from comparison results with Gaia: standard deviation median residuals ($...
We present a catalog of 138,665 radio sources derived from the initial 1550 deg2 FIRST survey. The survey parameters are reviewed, and map depicting coverage for first two observing sessions is presented. then describe in detail our algorithm source detection parameterization, as well procedures constructing final catalog. results extensive tests astrometric photometric accuracy, uncertainties extent morphological characterization, Source positions all good to better than 1'', flux density...
We present the results from a survey of i-dropout objects selected ∼1550 deg2 multicolor imaging data Sloan Digital Sky Survey to search for luminous quasars at z ≳ 5.8. Objects with i*-z* > 2.2 and z* < 20.2 are selected, follow-up J-band photometry is used separate L- T-type cool dwarfs high-redshift quasars. describe discovery three new quasars, SDSSp J083643.85+005453.3 (z = 5.82), J130608.26+035626.3 5.99), J103027.10+052455.0 6.28). The quasar radio source flux 1.1 mJy 20 cm. spectra...
We present moderate-resolution Keck spectroscopy of quasars at z = 5.82, 5.99, and 6.28, discovered by the Sloan Digital Sky Survey (SDSS). find that Lyα absorption in spectra these evolves strongly with redshift. To ∼ 5.7, as expected from an extrapolation lower redshifts. However, highest-redshift object, SDSSp J103027.10+052455.0 (z 6.28), average transmitted flux is 0.0038 ± 0.0026 times continuum level over 8450 Å < λ 8710 (5.95 zabs 6.16), consistent zero flux. Thus drops a factor...
Deep Impact collided with comet Tempel 1, excavating a crater controlled by gravity. The comet's outer layer is composed of 1- to 100-micrometer fine particles negligible strength (<65 pascals). Local gravitational field and average nucleus density (600 kilograms per cubic meter) are estimated from ejecta fallback. Initial were hot (>1000 kelvins). A large increase in organic material occurred during after the event, smaller changes carbon dioxide relative water. On approach,...
We present the discovery of three new quasars at z > 6 in ∼ 1300 deg2 Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z = 6.43), J104845.05+463718.3 6.23), and J163033.90+401209.6 6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from positions Lyman break. They only accurate to ∼0.05 could be affected by presence broad absorption line systems. last object has a strength more typical lower redshift quasars. Based on sample six 5.7 that...
We study the process of cosmic reionization and estimate ionizing background in IGM using Lyman series absorption spectra four quasars at 5.710^{-3} z~6. At this redshift, mass-averaged neutral hydrogen fraction is larger than 1%; mildly overdense regions (delta > 3) are still mostly comoving mean free path photons shorter 8 Mpc. Comparison with simulations cosmological shows that observed properties z~6 typical those era end overlap stage when individual HII merge. Thus, marks epoch. The...
The Very Large Array Sky Survey (VLASS) is a synoptic, all-sky radio sky survey with unique combination of high angular resolution ($\approx$2.5"), sensitivity (a 1$\sigma$ goal 70 $\mu$Jy/beam in the coadded data), full linear Stokes polarimetry, time domain coverage, and wide bandwidth (2-4 GHz). first observations began September 2017, observing for will finish 2024. VLASS use approximately 5500 hours on Karl G. Jansky (VLA) to cover whole visible VLA (Declination $>-40^{\circ}$), total...
We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 15 with a Sloan Digital Sky Survey (SDSS) (optical, r* ∼ 22.2) source in 1230 deg2 sky. The matched sample represents ∼30% 108,000 0.1% 2.5 × 107 SDSS studied region. spectra are available for 4300 galaxies 1154 quasars from control 140,000 20,000 1030 Here we analyze only core sources, which dominate sample; fraction SDSS-FIRST complex morphology is...
We present the discovery of seven quasars at z > 5.7, selected from ∼2000 deg2 multicolor imaging data Sloan Digital Sky Survey. The new have redshifts 5.79 to 6.13. Five are as part a complete flux-limited sample in SDSS northern Galactic cap; two larger photometric errors and not sample. One quasars, J1335+3533 (z = 5.93), exhibits no emission lines; 3 σ limit on rest-frame equivalent width Lyα+N V line is 5 Å. It highest redshift lineless quasar known could be gravitational lensed galaxy,...
view Abstract Citations (489) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray emission from the winds of hot stars. Lucy, L. B. ; White, R. A phenomenological theory is proposed for structure unstable line-driven early-type These are conjectured to break up into a population blobs that being radiatively driven through, and confined by ram pressure an ambient gas not itself driven. Radiation bow shocks preceding can account luminosity...
We measure the morphology--density relation (MDR) and morphology-radius (MRR) for galaxies in seven z ~ 1 clusters that have been observed with Advanced Camera Surveys on board Hubble Space Telescope. Simulations independent comparisons of ourvisually derived morphologies indicate ACS allows one to distinguish between E, S0, spiral down zmag = 24, corresponding L/L* 0.21 0.30 at 0.83 1.24, respectively. adopt density radius estimation methods match those used lower redshift order study...
The Guide Star Catalog II (GSC-II) is an all-sky database of objects derived from the uncompressed Digitized Sky Surveys that Space Telescope Science Institute has created Palomar and UK Schmidt survey plates made available to community. Like its predecessor (GSC-I), GSC-II was primarily provide guide star information observation planning support for Hubble Telescope. This version, however, already employed at some ground-based new-technology telescopes such as GEMINI, VLT, TNG, will also be...
The FIRST survey, begun over twenty years ago, provides the definitive high-resolution map of radio sky. This VLA survey reaches a 20cm detection sensitivity 1 mJy 10,575 deg**2 largely coincident with SDSS area. Images and catalog containing 946,432 sources are available through web site (http://sundog.stsci.edu). We record here authoritative history, including hardware software changes that affect catalog's reliability completeness. use recent JVLA observations to test astrometry flux...
This paper describes the organization of database and catalog data products from Pan-STARRS1 $3\pi$ Steradian Survey. The are available in form an SQL-based relational MAST, Mikulski Archive for Space Telescopes at STScI. is described detail, including construction database, provenance data, schema, how tables related. Examples queries a range science goals included.
We present the discovery of nine quasars at $z\sim6$ identified in Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey SDSS footprint. Our final sample consists 52 $5.7<z\le6.4$, including 29 with $z_{\rm AB}\le20$ mag selected from 11,240 deg$^2$ single-epoch (the main survey), 10 $20\le z_{\rm AB}\le20.5$ 4223 overlap regions (regions two or more scans), and 13 down to AB}\approx22$ 277 Stripe 82. They span a wide luminosity range $-29.0\le M_{1450}\le-24.5$....
Abstract The PHANGS program is building the first data set to enable multiphase, multiscale study of star formation across nearby spiral galaxy population. This effort enabled by large survey programs with Atacama Large Millimeter/submillimeter Array (ALMA), MUSE on Very Telescope, and Hubble Space Telescope (HST), which we have obtained CO(2–1) imaging, optical spectroscopic mapping, high-resolution UV–optical respectively. Here, present PHANGS-HST, has NUV– U – B V I imaging disks 38...
This is the fourth paper in a series aimed at finding high-redshift quasars from five-color imaging data taken along Celestial Equator by SDSS. during its commissioning phase. In this paper, we use color-selected sample of 39 luminous presented Paper III to derive evolution quasar luminosity function over range 3.6
view Abstract Citations (393) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A New Catalog of 53,522 4.85 GHz Sources Becker, Robert H. ; White, Richard L. Edwards, Alan catalog sources between 0^deg^ and 75^deg^ declination has been generated from observations taken with the NRAO Green Bank 300 foot (91 m) telescope. The flux limit is dependent on ranges ~40 mJy at to 20 60^deg^. source positions given in have a 95% confidence radius ~50"....