Karl Förster
A5032893133- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Cosmology and Gravitation Theories
- Calibration and Measurement Techniques
- CCD and CMOS Imaging Sensors
- Particle Detector Development and Performance
- Photocathodes and Microchannel Plates
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
- History and Developments in Astronomy
- Dark Matter and Cosmic Phenomena
- Advanced X-ray Imaging Techniques
- Mechanics and Biomechanics Studies
- Geophysics and Gravity Measurements
- Nuclear Physics and Applications
California Institute of Technology
2013-2024
Space Micro (United States)
2021
European Space Astronomy Centre
2018-2021
NASA Astrobiology Institute
2003
Harvard University
2001
Center for Astrophysics Harvard & Smithsonian
1999
Columbia University
1997-1999
University of Cologne
1991
We give an overview of the Galaxy Evolution Explorer (GALEX), a NASA Mission launched on April 28, 2003. GALEX is performing first space UV sky-survey, including imaging and grism surveys in two bands (1350-1750 Angstroms 1750-2750 Angstroms). The include all-sky survey (m[AB] ~ 20.5), medium 1000 square degrees 23), deep 100 25), nearby galaxy survey. Spectroscopic (R=100-200) are underway with various depths sky coverage. Many targets overlap existing or planned surveys. will use measured...
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates band from 3 to 79 keV, extending sensitivity of far beyond ∼10 keV cutoff achieved by all previous satellites. inherently low background associated with concentrating light enables probe hard sky a more than 100-fold improvement over collimated or coded mask instruments that have operated this bandpass. Using its unprecedented...
We measure star formation rates (SFRs) of ≈50,000 optically selected galaxies in the local universe (z ≈ 0.1)—from gas-rich dwarfs to massive ellipticals. obtain dust-corrected SFRs by fitting GALEX (ultraviolet) and SDSS photometry a library dust-attenuated population synthesis models. For star-forming galaxies, our UV-based compare remarkably well with those from SDSS-measured emission lines (Hα). Deviations perfect agreement are shown be due differences dust attenuation estimates. In...
We describe the calibration status and data products pertaining to GR2 GR3 releases of Galaxy Evolution Explorer (GALEX). These have identical pipeline calibrations that are significantly improved over GR1 release. GALEX continues survey sky in far-ultraviolet (FUV, ~154 nm) near-ultraviolet (NUV, ~232 bands, providing simultaneous imaging with a pair photon-counting, microchannel plate, delay line readout detectors. 1.25° field view detectors well suited ultraviolet observations because...
We present measurements of the baryon acoustic peak at redshifts z = 0.44, 0.6 and 0.73 in galaxy correlation function final dataset WiggleZ Dark Energy Survey. combine our with lower-redshift from 6-degree Field Galaxy Survey Sloan Digital Sky Survey, producing a stacked survey which statistical significance detection is 4.9-sigma relative to zero-baryon model no peak. fit cosmological models this combined oscillation (BAO) comprising six distance-redshift data points, compare results...
We present images, integrated photometry, and surface-brightness color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; λeff = 1516 Å) near-ultraviolet (NUV; 2267 bands. Our catalog objects is derived primarily from GALEX Nearby Galaxies Survey (NGS) supplemented larger than 1' diameter serendipitously found these fields other exposures similar greater depth. The sample analyzed here adequately...
We perform a joint determination of the distance-redshift relation and cosmic expansion rate at redshifts z = 0.44, 0.6 0.73 by combining measurements baryon acoustic peak Alcock-Paczynski distortion from galaxy clustering in WiggleZ Dark Energy Survey, using large ensemble mock catalogues to calculate covariance between measurements.We find that D A (z) (1205 ± 114, 1380 95, 1534 107) Mpc H(z) (82.6 7.8, 87.9 6.1, 97.3 7.0) km s -1 these three redshifts.Further our results with other...
The WiggleZ Dark Energy Survey is a survey of 240,000 emission line galaxies in the distant universe, measured with AAOmega spectrograph on 3.9-m Anglo-Australian Telescope (AAT). target are selected using ultraviolet photometry from GALEX satellite, flux limit NUV<22.8 mag. redshift range containing 90% 0.2<z<1.0. primary aim to precisely measure scale baryon acoustic oscillations (BAO) imprinted spatial distribution these at look-back times 4-8 Gyrs. Detailed forecasts indicate will BAO...
We have analyzed the bivariate distribution of galaxies as a function ultraviolet-optical colors and absolute magnitudes in local universe. The sample consists with redshifts optical photometry from Sloan Digital Sky Survey (SDSS) main galaxy matched detections near-ultraviolet (NUV) far-ultraviolet (FUV) bands Medium Imaging being carried out by Galaxy Evolution Explorer (GALEX) satellite. In (NUV − r)0.1 versus Mr,0.1 color-magnitude diagram, separate into two well-defined blue red...
We present precise measurements of the growth rate cosmic structure for redshift range 0.1 < z 0.9, using redshift-space distortions in galaxy power spectrum WiggleZ Dark Energy Survey. Our results, which have a precision around 10 per cent four independent bins, are well fitted by flat Λ cold dark matter (ΛCDM) cosmological model with density parameter Ωm= 0.27. analysis hence indicates that this provides self-consistent description through large-scale perturbations and homogeneous...
We have initiated a search for extended ultraviolet disk (XUV-disk) galaxies in the local universe. Here we compare GALEX UV and visible-NIR images of 189 nearby (D < 40 Mpc) S0-Sm included Atlas Nearby Galaxies present first catalog XUV-disk galaxies. find that are surprisingly common but varied relative (UV/optical) extent morphology. Type 1 objects (≳20% incidence) structured, UV-bright/optically faint emission features outer disk, beyond traditional star formation threshold. 2 (~10%...
We present significant improvements in cosmic distance measurements from the Wig-gleZ Dark Energy Survey, achieved by applying reconstruction of baryonic acoustic feature technique.We show using both data and simulations that technique can often be effective despite patchiness survey, edge effects shot-noise.We investigate three redshift bins range 0.2 < z 1, all find improvement after detection its usage as a standard ruler.We measure model independent measures D V r fid s /r 1716± 83 Mpc,...
We present the calibration of Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray satellite. used Crab as primary effective area calibrator and constructed a piece-wise linear spline function to modify vignetting response. The achieved residuals for all off-axis angles energies, compared assumed spectrum, are typically better than ±2% up 40 keV 5%–10% above due limited counting statistics. An empirical adjustment theoretical two-dimensional point-spread (PSF) was found using several strong...
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
This paper presents cosmological results from the final data release of WiggleZ Dark Energy Survey. We perform full analyses different models using power spectra measured at $z=0.22$, 0.41, 0.60, and 0.78, combined with other sets. The limiting factor in this analysis is theoretical modeling galaxy spectrum, including nonlinearities, bias, redshift-space distortions. In we assess several methods for testing them against Gigaparsec simulations (GiggleZ). fit a base set six parameters,...
We report the first year on-orbit performance results for Galaxy Evolution Explorer (GALEX), a NASA Small that is performing survey of sky in two ultraviolet bands. The instrument comprises 50 cm diameter modified Ritchey-Chretien telescope with 1.25 degree field view, selectable imaging and objective grism spectroscopic modes, an innovative optical system thin-film multilayer dichroic beam splitter enables simultaneous by pair photon counting, microchannel plate, delay line readout...
We compare the dust attenuation properties of two samples galaxies purely selected in Galaxy Evolution Explorer (GALEX) near-ultraviolet band (NUV; 1750-2750 Å, λmean = 2310 Å) and far-infrared (FIR) at 60 μm. These are built using GALEX IRAS sky surveys over ~600 deg2. The NUV-selected sample contains 95 detected down to NUV 16 mag (AB system). Eighty-three this spiral or irregular, only them not FIR-selected is from PSCz survey, which complete 0.6 Jy. Among 163 sources, we select 118...
In a companion Letter (Arnouts et al.) we present new measurements of the galaxy luminosity function at 1500 Å out to z ~ 1 using Galaxy Evolution Explorer VIMOS-VLT Deep Survey observations (1039 galaxies with NUV ≤ 24.5 and > 0.2) higher existing data sets. this use same sample study evolution FUV density ρ1500. We detect consistent (1 + z)2.5±0.7 rise z)0.5±0.4 for 1. The from most UV-luminous (UVLGs) is undergoing dramatic (30 times) between 0 < UVLGs are responsible significant fraction...
We have studied ~2100 early-type galaxies in the SDSS DR3 which been detected by GALEX Medium Imaging Survey (MIS), redshift range 0 < z 0.11. Combining UV photometry with corollary optical data from SDSS, we find that, at a 95% confidence level, least ~30% of this sample to colors consistent some recent star formation within last Gyr. In particular, an NUV − r color less than 5.5 are very likely experienced such formation, taking into account possibility contribution flux upturn phenomenon....
Ultraviolet imaging with the Galaxy Evolution Explorer (GALEX) has revealed an extensive sample of UV-bright stellar complexes in extreme outer disk M83, extending to about 4 times radius at which majority H II regions are detected (R = 51, or 6.6 kpc). These sources typically associated large-scale filamentary I structures warped M83 and distributed beyond galactocentric radii molecular interstellar medium yet been detected. We present measured properties these complexes, including far-UV...
We use the UV-optical color magnitude diagram in combination with spectroscopic and photometric measurements derived from SDSS sample to measure distribution of galaxies local universe (z < 0.25) their physical properties as a function specific star formation rate (SFR/M⋆) stellar mass (M⋆). Throughout this study our emphasis is on off "star-forming sequence." discuss how characteristics along sequence are related scaling relations typically for different morphological types. find, among...
We present the results of a determination galaxy luminosity function at ultraviolet wavelengths redshifts z = 0.0-0.1 from Galaxy Evolution Explorer (GALEX) data. determined in GALEX far-UV and near-UV bands sample galaxies with UV magnitudes between 17 20 that are drawn total 56.73 deg2 fields overlapping bJ-selected Two-Degree Field Redshift Survey. The resulting functions fainter than previous estimates result densities 1025.55±0.12 1025.72±0.12 ergs s-1 Hz-1 Mpc-3 1530 2310 Å,...
We introduce a new quantity, the mass flux density of galaxies evolving from blue sequence to red sequence. propose simple technique for constraining this using volume corrected number in extinction-corrected UV-optical color magnitude distribution, stellar age indexes H-delta-a and D_n(4000), prescription spectral evolution quenched star formation history. exploit excellent separation sequences NUV-r band color-magnitude diagram. The final value we measure, 0.033 M_sun yr^-1 Mpc^-3, is...