A5072212826- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Magnetic confinement fusion research
- Astrophysical Phenomena and Observations
- Advanced optical system design
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Scientific Research and Discoveries
- Semiconductor Lasers and Optical Devices
- Optical Coatings and Gratings
- CCD and CMOS Imaging Sensors
- History and Developments in Astronomy
- Photonic and Optical Devices
- Optical Systems and Laser Technology
- Calibration and Measurement Techniques
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Fusion materials and technologies
- Optical Polarization and Ellipsometry
- Superconducting Materials and Applications
Durham University
2016-2025
Indiana Cancer Consortium
2024-2025
Yale University
2020
University of California, Berkeley
1995-2020
Culham Centre for Fusion Energy
2019-2020
Culham Science Centre
2019-2020
Australian National University
2020
University of Science and Technology of China
2020
Southwestern Institute of Physics
2020
Massachusetts Institute of Technology
2019
Using traditional morphological classifications of galaxies in 10 intermediate-redshift (z~0.5) clusters observed with WFPC-2 on the Hubble Space Telescope, we derive relations between morphology and local galaxy density similar to that found by Dressler for low-redshift clusters. Taken collectively, `morphology-density' relationship, M-D, these more distant, presumably younger is qualitatively sample, but a detailed comparison shows two substantial differences: (1) For our M-D relation...
We present a striking new Hubble Space Telescope (HST) observation of the rich cluster Abell 2218 taken with Wide Field Planetary Camera 2. HST's restored image quality reveals sizable number gravitationally lensed features in this cluster, significantly more than had been identified by using ground-based telescopes. The brightest arcs are resolved HST and show internal that enable us to identify multiply imaged examples, confirming improving mass models determined from observations....
In this paper we follow up on our previous detection of nuclear ionized outflows in the most massive (log(M*/Msun) >= 10.9) z~1-3 star-forming galaxies (Forster Schreiber et al.), by increasing sample size a factor six (to 44 above log(M*/Msun) from combination SINS/zC-SINF, LUCI, GNIRS, and KMOS^3D spectroscopic surveys. We find fairly sharp onset incidence broad emission (FWHM Ha, [NII], [SII] lines ~ 450-5300 km/s), with large [NII]/Ha ratios, 10.9, about two thirds mass range exhibiting...
The KMOS Redshift One Spectroscopic Survey (KROSS) is an ESO-guaranteed time survey of 795 typical star-forming galaxies in the redshift range z = 0.8–1.0 with instrument on Very Large Telescope. In this paper, we present resolved kinematics and star formation rates for 584 ∼ 1 galaxies. This constitutes largest near-infrared Integral Field Unit at to date. We demonstrate success our selection criteria 90 per cent targets found be H α emitters, which 81 are spatially resolved. fraction KROSS...
Abstract We describe the spectroscopic data processing pipeline of Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey about 40 million galaxies and quasars using purpose-built instrument on 4 m Mayall Telescope at Kitt Peak National Observatory. The main goal DESI to measure with unprecedented precision expansion history universe baryon acoustic oscillation technique growth rate structure space distortions. Ten spectrographs three cameras each disperse light...
Abstract A system of 5020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically retarget their optical fibers every 10–20 minutes, each to a precision several microns, with reconfiguration time fewer than 2 minutes. Over next 5 yr, they will enable newly constructed Dark Energy Spectroscopic Instrument (DESI) measure spectra 35 million galaxies and quasars. DESI produce largest 3D map universe date expansion...
We describe the Milky Way Survey (MWS) that will be undertaken with Dark Energy Spectroscopic Instrument (DESI) on Mayall 4m telescope at Kitt Peak National Observatory. Over next 5 yr DESI MWS observe approximately seven million stars Galactic latitudes |b|>20 degrees, an inclusive target selection scheme focused thick disk and stellar halo. also include several high-completeness samples of rare types, including white dwarfs, low-mass within 100pc Sun, horizontal branch stars. summarize...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is currently measuring the spectra of 40 million galaxies and quasars, largest such survey ever made to probe nature cosmological dark energy. 4 m Mayall telescope at Kitt Peak National Observatory has been adapted for DESI, including construction a 3.°2 diameter prime focus corrector that focuses astronomical light onto 0.8 focal surface with excellent image quality over DESI bandpass 360–980 nm. wide-field includes six lenses, as...
The small scatter observed for the (U-V) colors of spheroidal galaxies in nearby clusters provides a powerful constraint on history star formation dense environments. However, with local data alone, it is not possible to separate models where assembled synchronously over redshifts 0 < z 1 from ones formed stochastically at much earlier times. Here we attempt resolve this ambiguity via high-precision rest-frame UV-optical photometry large sample morphologically selected three ~ 0.54 that have...
The 2dF (Two-degree Field) facility at the prime focus of Anglo-Australian Telescope provides multiple-object spectroscopy over a 2° field view. Up to 400 target fibres can be independently positioned by complex robot. Two spectrographs provide spectra with resolutions between 500 and 2000, wavelength ranges 440 110 nm respectively. began routine observations in 1997. was designed primarily for galaxy redshift surveys has number innovative features. large corrector lens incorporates an...
We present new results of a program to study the detailed morphologies galaxies in intermediate-redshift clusters and hence understand physical origin enhanced star formation seen these environments at earlier epochs. Deep, high-resolution imagery has been obtained three rich clusters, AC 103, 118, 114 z = 0.31, through R (F702W) filter Wide Field Planetary Camera (WFPC2) Hubble Space Telescope (HST). For 103 single three-orbit pointings covering central ~0.5 × 0.5 h-1 Mpc area have...
We have investigated the formation of globular cluster (GC) systems in fiducial semi-analytic model galaxy Cole et al., by assuming that GCs are formed at high redshifts (z>5) protogalactic fragments, and during subsequent gas-rich merging these fragments. Under assumptions we simulated GC 450 elliptical galaxies, find majority (93 per cent) intrinsically bimodal metallicity. that, mean, metal-rich subpopulations younger than metal-poor subpopulations, with ages 9 12 Gyr respectively, mean...
view Abstract Citations (227) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Morphological Studies of the Galaxy Populations in Distant ``Butcher-Oemler'' Clusters with HST. I. AC 114 at Z = 0.31 and Abell 370 0.37 Couch, Warrick J. ; Ellis, Richard S. Sharples, Ray M. Smail, Ian We present first results an ongoing program we are undertaking Wide Field Camera Hubble Space Telescope (HST) to understand physical origin enhanced star formation...
We present the most extensive combined photometric and spectroscopic study to date of enormous globular cluster (GC) system around M87, central giant elliptical galaxy in nearby Virgo cluster. Using observations from DEIMOS LRIS at Keck, Hectospec on MMT, we derive new, precise radial velocities for 451 GCs with projected radii ~ 5 185 kpc. combine these measurements literature data a total sample 737 objects, which use re-examination kinematics GC M87. The are analyzed context archival...
We present the first results from KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≳ 0.6 AGN. galaxy-integrated spectra 89 X-ray (L2–10 keV = 1042–1045 erg s−1), for which we observed [O iii] (z ≈ 1.1–1.7) or Hα emission 0.6–1.1). The targets have luminosities representative parent population and explore emission-line as function luminosity. For targets, ≈50 per cent ionized gas...
Intracluster stellar populations are a natural result of tidal interactions in galaxy clusters. Measuring these is difficult, but important for understanding the assembly most massive galaxies. The Coma cluster one nearest truly clusters, and host to correspondingly large system globular clusters (GCs). We use imaging from HST/ACS Cluster Survey present first definitive detection population intracluster GCs (IGCs) that fills core not associated with individual GC surface density profile...
We present the correlations between stellar mass, star formation rate (SFR) and [NII]/Ha flux ratio as indicator of gas-phase metallicity for a sample 222 galaxies at 0.8 < z 2.6 log(M*/Msun)=9.0-11.5 from LUCI, SINS/zC-SINF KMOS3D surveys. This provides unique analysis mass-metallicity relation (MZR) over an extended redshift range using consistent data techniques strong-line indicator. find constant slope low-mass end can fully describe its evolution through characteristic turnover mass...
We present dynamical measurements from the KMOS (K-band Multi-Object Spectrograph) Deep Survey (KDS), which is comprised of 77 typical star-forming galaxies at z $\simeq$ 3.5 in mass range 9.0 < log(M$_{\star}$/M$_{\odot}$) 10.5. These constrain internal dynamics, intrinsic velocity dispersions (σ$_{int}$) and rotation velocities (V$_{C}$) high redshift Universe. The mean dispersion our sample σ$_{int}$ = $70.8^{+3.3}_{-3.1}$ km s$^{-1}$, revealing that increasing average with redshift,...
We analyse the velocity dispersion properties of 472 z ∼ 0.9 star-forming galaxies observed as part KMOS Redshift One Spectroscopic Survey (KROSS). The majority this sample is rotationally dominated (83 ± 5 per cent with vC/σ0 > 1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, median intrinsic final σ0 = 43.2 0.8 km s−1 a rotational to ratio 2.6 0.1. To explore relationship between dispersion, stellar mass, star formation rate, redshift, we...
ABSTRACT We analyze the angular momenta of massive star-forming galaxies (SFGs) at peak cosmic star formation epoch ( z ∼ 0.8–2.6). Our sample ∼360 log( M * / ⊙ ) 9.3–11.8 SFGs is mainly based on KMOS 3D and SINS/zC-SINF surveys H α kinematics, collectively provides a representative subset population. The inferred halo scale momentum distribution broadly consistent with that theoretically predicted for their dark matter halos, in terms mean spin parameter <?CDATA $\langle \lambda \rangle $?>...
Abstract We present Dark Energy Spectroscopic Instrument (DESI) observations of the inner halo M31, which reveal kinematics a recent merger—a galactic immigration event—in exquisite detail. Of 11,416 sources studied in 3.75 hr on-sky exposure time, 7438 are M31 with well-measured radial velocities. The intricate coherent kinematic structure positions and velocities individual stars: streams, wedges, chevrons. While hints structures have been previously detected this is first time they seen...
We present images of the recent galaxy merger NGC 3256 obtained with Wide Field Planetary Camera 2 Hubble Space Telescope in B and I filters. show that there is a large population more than 1000 compact, bright, blue objects this within 7 kpc × region studied. These have sizes, colors, luminosities like those expected for young Galactic globular clusters, ages ranging from few to several hundred megayears. On basis, we identify at least some fraction as clusters. The cluster system makes up...
We have obtained multifiber spectra of 125 early-type galaxies in the Coma cluster galaxies, using Hydra bench spectrograph on 4 m telescope at Kitt Peak. The sample selection was based both color and morphology, care being taken to exclude intermediate late-type spirals. Surprisingly, a large fraction (about 1/3) all field located approximately 40' SW center exhibits enhanced Balmer absorption lines or emission lines, indicative recent star formation nuclear activity. In contrast, very few...
We analyse the detailed distribution of star-forming and post-starburst members in three distant (z = 0.31) galaxy clusters terms evolutionary sequences that incorporate secondary bursts star formation on pre-existing stellar populations. Using number density spectroscopically confirmed EW(H´) versus B — R plane from existing data, for a larger K-limited sample U I K newly acquired infrared images, we demonstrate proportion cluster undergoing during last ∼ 2 Gyr prior to epoch observation is...