A5035068581- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- SAS software applications and methods
- CCD and CMOS Imaging Sensors
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Radiation Therapy and Dosimetry
- Ocular and Laser Science Research
- Optical Systems and Laser Technology
- Ionosphere and magnetosphere dynamics
- Calibration and Measurement Techniques
- Scientific Measurement and Uncertainty Evaluation
- Radioactive Decay and Measurement Techniques
- Welding Techniques and Residual Stresses
- Remote Sensing in Agriculture
University of Oslo
2015-2024
Institute of Theoretical Physics
2022
Laboratoire d’Astrophysique de Marseille
2008-2011
Netherlands Institute for Radio Astronomy
2009
University of Hawaii System
1999-2007
University of Hawaiʻi at Mānoa
2002-2007
University of Pennsylvania
2004
Novo Nordisk (Denmark)
2002-2003
We study the mass distribution of a sample 28 galaxy clusters using strong and weak lensing observations. The are selected via their properties as part Sloan Giant Arcs Survey (SGAS) from Digital Sky (SDSS). Mass modelling information giant arcs is combined with measurements deep Subaru/Suprime-cam images to primarily obtain robust constraints on concentration parameter shape distribution. find that cvir steep function mass, cvir∝M−0.59±0.12vir, value roughly consistent...
The Shear TEsting Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak lensing measurement, in preparation for next generation wide-field surveys. We review sixteen current emerging shear measurement methods common language, assess their performance by running them (blindly) on simulated images that contain known signal. determine features algorithms most successfully recover input parameters. achieve previously unattained discriminatory precision our...
The Local Cluster Substructure Survey (LoCuSS, Smith et al.) is a systematic multi-wavelength survey of >100 X-ray luminous galaxy clusters (0.14
We infer the properties of massive star populations using far-ultraviolet stellar continua 61 star-forming galaxies: 42 at low-z observed with HST and 19 z~2 from Megasaura sample. fit each continuum a linear combination up to 50 single age metallicity Starburst99 models. From these fits, we derive light-weighted ages metallicities, which agree wind photospheric spectral features, shapes strengths ionizing continua. Inferred metallicities span 0.05-1.5 Z$_\odot$ are similar measured nebular...
Abstract We derive and compare the fractions of cool-core clusters in Planck Early Sunyaev–Zel’dovich sample 164 with <?CDATA $z\leqslant 0.35$?> a flux-limited X-ray 100 0.30$?> , using Chandra observations. use four metrics to identify clusters: (1) concentration parameter, which is ratio integrated emissivity profile within 0.15 r 500 that ; (2) 40 kpc 400 kpc; (3) cuspiness gas density profile, negative logarithmic derivative respect radius, measured at 0.04 (4) central density, 0.01 ....
We update the all-sky Planck catalogue of 1227 clusters and cluster candidates (PSZ1) published in March 2013, derived from detections Sunyaev–Zeldovich (SZ) effect using first 15.5 months satellite observations. As an addendum, we deliver updated version PSZ1 catalogue, reporting further confirmation 86 Planck-discovered clusters. In total, now contains 947 confirmed clusters, which 214 were as newly discovered through follow-up observations undertaken by Collaboration. The redshifts for...
We present rest-frame ultraviolet and optical spectroscopy of the brightest lensed galaxy yet discovered, at redshift z = 2.4. This source reveals a characteristic, triple-peaked Lyman {\alpha} profile which has been predicted by various theoretical works but to our knowledge not unambiguously observed previously. The feature is well fit superposition two components: double-peak emerging from substantial radiative transfer, narrow, central component resulting directly escaping photons;...
Abstract We measure the gas-phase abundances of elements He, N, O, Ne, S, Ar, and Fe in an individual H ii region known to be leaking Lyman-continuum photons Sunburst Arc, a highly magnified galaxy at redshift z = 2.37. detect temperature-sensitive auroral lines [S ] λλ 4070, 4076, [O iii λ 4363, 6314, 7320, 7330, [Ne 3343 stacked spectrum five multiple images emitter (LCE), from which we directly electron temperature low-, intermediate-, high-ionization zones. also density-sensitive...
The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. shapes distant galaxies can be used to determine the properties dark energy and nature gravity, because light from those bent by gravity intervening matter. observed galaxy images appear distorted, although only slightly, their must precisely disentangled effects pixelisation, convolution noise. worldwide gravitational lensing community...
We measure [C iii] 1907, C 1909 Å emission lines in 11 gravitationally lensed star-forming galaxies at z ∼ 1.6–3, finding much lower equivalent widths than previously reported for fainter galaxies. While it is not yet clear what causes some to be strong emitters, a universal property of distant also examine 46 the local universe, using archival spectra from GHRS, FOS, and STIS on HST IUE. Twenty percent these show emission, with < −5 Å. Three nearby as large most extreme emitters observed...
Abstract Extreme, young stellar populations are considered to be the primary contributor cosmic reionization. How Lyman continuum (LyC) escapes these galaxies remains highly elusive, and it is challenging observe this process in actual LyC emitters without resolving relevant physical scales. We investigate Sunburst Arc, a strongly lensed emitter at z = 2.37 that reveals an exceptionally small-scale (tens of parsecs) region high escape. The small (<100 pc) LyC-leaking has extreme...
We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, J1531+3414, and J2111-0115), by combining detailed lens modeling with weak shear measured from deep Subaru Suprime-cam images. Weak signals are detected at high significance for all clusters, whose redshifts range z=0.28 to 0.64. demonstrate that adding information known arc significantly improves constraints on the density profile, compared those obtained...
We present results from a spectroscopic program targeting 26 strong lensing cluster cores that were visually identified in the Sloan Digital Sky Survey (SDSS) and Second Red-Sequence Cluster (RCS-2). The galaxy lenses span redshift range of 0.2 < z 0.65, our spectroscopy reveals 69 unique background sources with redshifts as high z=5.200. also identify for 262 member galaxies measure velocity dispersions dynamical masses 18 clusters where we have N \geq 10 galaxies. include an accounting...
Abstract We introduce Project M eg a S ura : the Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas. comprises medium-resolution, rest-frame ultraviolet spectroscopy N = 15 bright gravitationally lensed galaxies at redshifts 1.68 < z 3.6, obtained with MagE spectrograph on telescopes. The spectra cover observed-frame wavelength range 3200 λ o 8280 Å; average spectral resolving power is R 3300. median spectrum has signal-to-noise ratio (S/N) 21 per resolution...
We study the abundance of star-forming and quiescent galaxies in a sample 21 clusters at 0.5 < z 0.7, detected with Planck satellite. Thanks to large volume probed by , these systems are extremely massive, provide an excellent laboratory any environmental effects on their galaxies’ properties. measure cluster galaxy stellar mass function (SMF), which is fundamental observable constrain formation evolution galaxies. Our measurements based homogeneous deep multi-band photometry spanning...
Abstract We stack the rest-frame ultraviolet spectra of N = 14 highly magnified gravitationally lensed galaxies at redshifts <?CDATA $1.6\lt z\lt 3.6$?> . The resulting new composite spans $900\lt {\lambda }_{\mathrm{rest}}\lt 3000$?> Å, with a peak signal-to-noise ratio (S/N) 103 per spectral resolution element (∼100 km s −1 ). It is highest S/N, spectrum z ∼ 2–3 yet published. reveals numerous weak nebular emission lines and stellar photospheric absorption that can serve as physical...
As part of an all-sky follow-up the Planck catalogue Sunyaev-Zeldovich (SZ) cluster candidates detected in first 14 months data, we are observing southern sky optical imaging and spectroscopy through ESO Large Programme. Inspection New Technology Telescope (NTT) R-and z-band data from our programme has revealed unusually large bright arc field PSZ1 G311.65−18.48. We establish basic photometric morphological properties provide conclusive evidence for gravitational lensing nature this object....
Ionizing photons escape a lensed galaxy Young, hot stars emit ultraviolet radiation, which can ionize neutral gas. The first generation of converted most the intergalactic gas in Universe from to ionized form during epoch reionization less than billion years after Big Bang. Rivera-Thorsen et al. took advantage gravitational lensing system observe 12 images same star-forming region distant and determined fraction that into medium. Although this is younger reionization, results provide clues...