D. E. Harris
A5042760912- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Astro and Planetary Science
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Semiconductor materials and devices
- Stellar, planetary, and galactic studies
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Planetary Science and Exploration
- Semiconductor materials and interfaces
- Seismology and Earthquake Studies
- Geophysics and Gravity Measurements
- Electron and X-Ray Spectroscopy Techniques
- Autoimmune Bullous Skin Diseases
Smithsonian Astrophysical Observatory
2009-2019
Center for Astrophysics Harvard & Smithsonian
2007-2017
RTI International
2017
Columbia University Irving Medical Center
2017
University of Utah
2011-2016
United States Coast Guard Academy
2016
Signal Processing (United States)
2014
National Radio Astronomy Observatory
2012
CFA Institute
1999-2010
Seattle University
1992-2009
Building on the legacy of Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program four spectroscopic surveys three scientific themes: dark energy cosmological parameters, history structure Milky Way, population giant planets around other stars. In keeping with SDSS tradition, will provide regular public releases all its data, beginning Data Release 8 (DR8), which was made in 2011 January includes SDSS-I SDSS-II images spectra reprocessed latest pipelines calibrations produced for...
ABSTRACT The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from Baryon Oscillation Spectroscopic (BOSS). This ninth release (DR9) of SDSS project includes 535,995 new galaxy spectra (median z ∼ 0.52), 102,100 quasar 2.32), and 90,897 stellar spectra, along with presented in previous releases. These were obtained BOSS spectrograph taken between 2009 December 2011 July. In addition, parameters pipeline, which determines radial velocities, surface temperatures,...
The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with instrumentation and surveys focused on Galactic structure chemical evolution, measurements of the baryon oscillation feature clustering galaxies quasar Ly alpha forest, radial velocity search for planets around ~8000 stars. This paper describes first data release SDSS-III (and eighth counting from beginning SDSS). includes five-band imaging roughly 5200 deg^2 Southern Cap, bringing total footprint SDSS to 14,555...
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in clustering matter over a larger volume than combined efforts all previous spectroscopic surveys large-scale structure. BOSS uses 1.5 million luminous galaxies as faint i = 19.9 10,000 deg2 BAO redshifts z < 0.7. Observations neutral hydrogen Lyα forest more 150,000 quasar spectra (g 22) will constrain redshift range 2.15 3.5. Early results from include first detection...
The Sloan Digital Sky Survey (SDSS) has been in operation since 2000 April. This paper presents the Tenth Public Data Release (DR10) from its current incarnation, SDSS-III. data release includes first spectroscopic Apache Point Observatory Galaxy Evolution Experiment (APOGEE), along with Baryon Oscillation Spectroscopic (BOSS) taken through 2012 July. APOGEE instrument is a near-infrared R ∼ 22,500 300 fiber spectrograph covering 1.514–1.696 μm. survey studying chemical abundances and radial...
The interaction of aqueous U(VI) with galena and pyrite surfaces under anoxic conditions has been studied by solution analysis spectroscopic methods. data indicate that uranyl uptake is strongly dependent on pH; maximum (>98%) occurs above a pH range between 4.8 5.5, depending experimental conditions. Increasing the sorbate/sorbent ratio results in relative decrease slower sorption kinetics. Auger electron spectroscopy (AES) indicates an inhomogeneous distribution sorbed uranium at surface....
We present a Chandra and XMM-Newton study of X-ray emission from the lobes 33 classical double radio galaxies quasars. report new detections lobe-related in 11 sources. Together with previous detections, we find that is detected at least one lobe ∼ 75% sample. For all measured flux can be attributed to inverse Compton scattering cosmic microwave background radiation, magnetic field strengths between 0.3Beq 1.3Beq, where value Beq corresponds equipartition electrons field, assuming filling...
We present the first high-resolution X-ray image of jet in M87 using Chandra X-Ray Observatory. There is clear structure and almost all optically bright knots are detected individually. The unresolved core brightest feature but only 2-3 times brighter than knot A (123 from core) inner HST-1 (10 core). optical positions consistent at 01 level, emission (A) marginally upstream peak. Detailed Gaussian fits to one-dimensional profile show distinct that not associated with specific features....
This review focuses on the X-ray emission processes of extra-galactic jets scales resolvable by sub arcsec resolution Chandra Observatory. It is divided into 4 parts. The introductory chapter reviews classical problems for jets, as well those associated directly with emission. Throughout this section, we deal dualisms low powered radio sources versus high galaxies and quasars; synchrotron models inverse Compton models; distinction between relativistic plasma responsible received radiation...
Superluminal motion is a common feature of radio jets in powerful γ-ray-emitting active galactic nuclei. Conventionally, the variable emission assumed to originate near central supermassive black hole where jet launched on parsec scales or smaller. Here we report discovery superluminal features within distinct flaring X-ray-emitting region nearby galaxy M87 with Very Long Baseline Array. This shows that these two phenomenological hallmarks—superluminal and high-energy variability—are...
We present a reanalysis of the Einstein Observatory high-resolution imager data, along with new radio and optical observations. These data are used to examine morphology M87 jet, together infrared UV from literature, construct x-ray spectra for jet nucleus. Two features isolated in images, which we associate radio/optical knots B D. The detailed is nearly identical bands. All have similar spectral index (S_nu_ proportional nu^-alpha^) α_rr_~0.5. At higher frequencies steepen optical/x-ray...
The quasar PKS 0637-753, the first celestial X-ray target of Chandra Observatory, has revealed asymmetric structure extending from 3 to 12 arcsec west quasar, coincident with inner portion jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At redshift z=0.651, is largest (~100 kpc) and most luminous (~10^{44.6} ergs/s) few so far X-rays. This letter presents high resolution jet, 42 ks data when 0637-753 was on-axis ACIS-S near optimum focus. For morphology closely matches...
We use new and archival Chandra data to investigate the X-ray emission from a large sample of compact hot spots FR II radio galaxies quasars 3C catalog. find that only most luminous tend be in good agreement with predictions synchrotron self-Compton model equipartition magnetic fields. At low spot luminosities inverse Compton are routinely exceeded by several orders magnitude, but this is never seen more spots. argue an additional component present low-luminosity luminosity controls ability...
We have made deep Chandra observations of three powerful Fanaroff-Riley type II (FR II) radio sources: two quasars (3C 263 and 3C 351) one galaxy 330). X-ray emission from hot spots lobes, as well the active nucleus, is detected in each source. model spots' synchrotron spectra using VLA, BIMA, Hubble Space Telescope data. In 330, at a level consistent with being self-Compton (SSC) emission, spot magnetic field close to equipartition value. 351, however, an SSC origin for X-rays would require...
The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with Chandra X-ray Observatory, offering early surprise of detection a remarkable jet. Several observations variety detector configurations contribute to total exposure time Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) about 100ks. A spatial analysis all available data, making use Chandra's resolving power 0.4 arcsec, reveals jet that extends 10 arcsec west...
The emission processes responsible for the observed X-rays from radio jets are commonly believed to be nonthermal, but in any particular case, it is unclear if synchrotron or one more varieties of inverse Compton predominates. We present a formulation relativistically moving jet ("IC/beaming") that relies on radio-emitting sources which energy densities particles and fields comparable. include nonisotropic nature scattering relativistic electrons photons cosmic microwave background (CMB)...
The X-ray intensity of knot HST-1, 0.85" from the nucleus radio galaxy M87, has increased by more than a factor 50 during last 5 years. optical increase is similar and our limited data indicate commensurate activity. We give primary results Chandra Observatory monitoring program consider some implications this extreme variability in relativistic jet. find that support 'modest beaming synchrotron' model as indicated earlier papers. Based on model, decay lightcurve appears to be dominated...
We present weak gravitational lensing analysis of 22 high-redshift (z >~1) clusters based on Hubble Space Telescope images. Most in our sample provide significant signals and are well detected their reconstructed two-dimensional mass maps. Combining the current results previous weak-lensing studies five other high-z clusters, we compare masses these with observables. revisit question whether presence most massive is tension LambdaCDM structure formation paradigm. find that tightly correlated...
Using an approximate analytical formulation we derive the spectrum of relativistic electrons from observed radio and X-ray data. Correction factors more exact numerical integrations are also given. The likelihood detections various types sources is discussed in relation to average magnetic field strength consider a class which may not be represented existing catalogues sources. Finally, few problems will encountered comparing observations mentioned.
We present images from five observations of the quasar 3C 273 with Chandra X-Ray Observatory. The jet has at least four distinct features that are not resolved in previous observations. first knot (A1) is very bright X-rays. Its X-ray spectrum well fitted a power law α = 0.60 ± 0.05 (where Sν ∝ ν-α). Combining this measurement lower frequency data shows pure synchrotron model can fit 1.647 GHz to 5 keV (over nine decades energy) 0.76 0.02, similar spectral slope. Thus, we place limit on...
We present Chandra X-ray monitoring of the M87 jet in 2002, which shows that intensity HST-1, an optical knot 0.8" from core, increased by a factor two 116 days and four 2 yrs. There was also significant flux decrease over months, with suggestive evidence for softening spectrum. From this variability behavior, we argue bulk emission HST-1 comes synchrotron emission. None other conceivable processes can match range observed characteristics. By estimating model parameters various relativistic...