A5063783844- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Calibration and Measurement Techniques
- Astro and Planetary Science
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Non-Destructive Testing Techniques
- Vehicle emissions and performance
- Pulsars and Gravitational Waves Research
- Engineering Education and Curriculum Development
- Vestibular and auditory disorders
- Planetary Science and Exploration
- SAS software applications and methods
- Construction Engineering and Safety
- Satellite Image Processing and Photogrammetry
- Neural and Behavioral Psychology Studies
- Geophysics and Gravity Measurements
University of Copenhagen
2013-2024
California Polytechnic State University
2015-2024
Kennedy Center
2024
University of Oslo
2017-2021
Cal Poly Corporation
2016
Rigshospitalet
1978-2015
Stockholm University
2011-2013
AlbaNova
2011-2013
Danish Working Environment Authority
2007-2013
Danish National Institute of Public Health
2009
We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to September 2009, for total 76 GRBs, and present an additional three pre-Swift not included in earlier sample. Furthermore, we publish 840 new points 42 GRB afterglows, sets 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A 080810. analyzed light curves all derived spectral energy distributions with best quality, allowing us estimate host...
Primordial neutral atomic gas, mostly composed of hydrogen, is the raw material for star formation in galaxies. However, there are few direct constraints on amount hydrogen (H i ) galaxies at early cosmic times. We analyzed James Webb Space Telescope (JWST) near-infrared spectroscopy distant galaxies, redshifts ≳8. From a sample 12 we identified three that show strong damped Lyman-α absorption due to H their local surroundings. The located spectroscopic 8.8, 10.2, and 11.4, corresponding 400...
The Lyman alpha emission line is an essential diagnostic tool for probing galaxy formation and evolution. Not only it commonly the strongest observable from high-redshift galaxies but its shape detailed information about host can be revealed. However, due to scattering nature of Lya photons increasing their path length in a non-trivial way, if dust present may severely suppressed altered. In order interpret observations correctly, thus crucial significance know how much emitted light...
We report on new imaging observations of the Lyman alpha emission line (Lyα), performed with Hubble Space Telescope, that comprise backbone Reference Sample. present images 14 starburst galaxies at redshifts 0.028 < z 0.18 in continuum-subtracted Lyα, Hα, and far ultraviolet continuum. show Lyα is emitted scales systematically exceed those massive stellar population recombination nebulae: as measured by Petrosian 20% radius, RP20, radii are larger than Hα factors ranging from 1 to 3.6, an...
We study the intergalactic transmission of radiation in vicinity Ly{\alpha} wavelength. Simulating sightlines through medium (IGM) detailed cosmological hydrosimulations, impact IGM on shape line profile from emitting galaxies at redshifts 2.5 to 6.5 is investigated. In particular we show that taking into account correlation density and velocity fields with galaxies, blue part spectrum may be appreciably reduced, even relatively low redshifts. This some cases provide an alternative...
We present high-resolution far-UV spectroscopy of the 14 galaxies Lyman Alpha Reference Sample; a sample strongly star-forming at low redshifts ($0.028 < z 0.18$). compare derived properties to global from multi band imaging and 21 cm HI interferometry single dish observations, as well archival optical SDSS spectra. Besides $\alpha$ line, spectra contain number metal absorption features allowing us probe kinematics neutral ISM evaluate depth covering fraction medium function line-of-sight...
The Lyman-alpha reference sample (LARS) is a program with the Hubble Space Telescope (HST) that provides of local universe laboratory galaxies in which to study astrophysics visibility and strength (Lya) line hydrogen. This article presents an overview survey, its selection function HST imaging observations. was selected from GALEX+SDSS catalogue at z=0.028-0.19, order allow Lya be captured combinations long pass filters Solar Blind Channel (SBC) HST/ACS. In addition, LARS utilises Halpha...
We present the detection of Ly α, [O iii], and H α emission associated with an extremely strong damped Lyman-α (DLA) system (N(H i) = 1022.10 cm-2) at z 2.207 towards quasar SDSS J113520.39 − 001053.56. This is largest i column density ever measured along a quasi-stellar object (QSO) line sight, though typical those often found in DLAs to gamma-ray bursts (GRBs). absorption can also be classified as ultra-strong Mg ii Å. The mean metallicity gas ( [Zn/H] −1.1) dust depletion factors [Zn/Fe]...
Strong gravitational lensing magnifies the flux from distant galaxies, allowing us to detect emission lines that would otherwise fall below detection threshold for medium-resolution spectroscopy. Here we present of temperature-sensitive oxygen three galaxies at 2<z<3.5, which enables directly determine abundances and thereby double number z>2 this has been possible. The have ~10% solar in agreement with strong line diagnostics. Carbon nitrogen ratios relative are sub-solar as expected young...
We report upon new results regarding the Lya output of galaxies, derived from Lyman alpha Reference Sample (LARS), focusing on Hubble Space Telescope imaging. For 14 galaxies we present intensity images in Lya, Halpha, and UV, maps Halpha/Hbeta, equivalent width (EW), Lya/Halpha. UV light profiles show they are well-fitted by S\'ersic profiles, but indices systematically lower than those (n approx 1-2 instead >~4). This reveals a general lack central concentration that is ubiquitous UV....
Context. One of the surprising early findings with JWST has been discovery a strong “roll-over” or softening absorption edge Ly α in large number galaxies at z ≳ 6, addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This interpreted as cumulative damped (DLA) wings high column densities neutral atomic hydrogen (H I ), signifying major gas accretion events formation these galaxies. Aims. To explore this new phenomenon systematically,...
<i>Context. <i/> Narrow-band surveys to detect Ly<i>α<i/> emitters are powerful tools for identifying high, and very redshift galaxies. Although samples increasing at redshifts , the nature of these galaxies is still poorly known. The number detected below also small.<i>Aims. We study properties compare them with those emitters.<i>Methods. present narrow-band imaging made MPG/ESO 2.2m telescope WFI (Wide Field Imager) detector. Using this data, we have searched emission-line objects. find...
We present photometric and spectroscopic observations at optical near-infrared wavelengths of the nearby type Ic SN 2007gr. These represent most extensive data-set to date any supernova this sub-type, with frequent coverage from shortly after discovery more than one year post-explosion. deduce a rise time B-band maximum 11.5 \pm 2.7 days. find peak magnitude M_B=-16.8, light curves which are remarkably similar so-called 'hypernova' 2002ap. In contrast, spectra SNe 2007gr 2002ap show marked...
We have initiated a survey using the newly commissioned X-shooter spectrograph to target candidate relatively metal-rich damped Lyman-alpha absorbers (DLAs). The spectral coverage of allows us search for not only emission, but also rest-frame optical emission lines. chosen DLAs where strongest lines ([OII], [OIII], Hbeta and Halpha) fall in NIR atmospheric transmission bands. In this first paper resulting from survey, we report on discovery galaxy counterpart z_abs = 2.354 DLA towards...
We have studied the afterglow of gamma-ray burst (GRB) February 18, 2006. This is a nearby long GRB, with very low peak energy, and therefore classified as an X-ray Flash (XRF). XRF 060218 clearly associated supernova -- dubbed SN 2006aj. present early spectra for 2006aj well optical lightcurves reaching out to 50 days past explosion. Our define rise times, lightcurve shapes absolute magnitudes in U, V R bands, we compare these data other relevant supernovae. evolved quite fast, somewhat...
The optical afterglow spectrum of GRB050401 (at z=2.8992+/-0.0004) shows the presence a DLA, with log(nHI)=22.6+/-0.3. This is highest column density ever observed in and about five times larger than strongest DLA detected so far any QSO spectrum. From spectrum, we also find very large Zn density, allowing us to infer an abundance [Zn/H]=-1.0+/-0.4. These columns are supported by X-ray from Swift-XRT which (in excess Galactic) log(nH)=22.21^{+0.06}_{-0.08} assuming solar abundances z=2.9)....
We present results obtained with a 3D, Ly alpha radiative transfer code, applied to fully cosmological galaxy formation simulation. The developed Monte Carlo code is capable of treating an arbitrary distribution source emission, neutral hydrogen density, temperature, and peculiar velocity the interstellar medium. investigate influence resonant scattering on appearance properties young galaxies by applying simulated "Lyman Break Galaxy" at redshift z = 3.6, star rate 22 M_sun/yr total...
[Abridged]. Here, we report on the discovery of galaxy counterpart z_abs=2.58 DLA line-of-sight to z=3.07 quasar SDSS J091826.16+163609.0. The is detected in OIII 5007 and OII 3726,3729 emission lines redshifted into NIR at an impact parameter 16 kpc. Ly-alpha not detected. upper limit implies that from this suppressed by more than order magnitude. amongst most metal-rich DLAs studied so far comparable redshifts. We find evidence for substantial depletion refractory elements onto dust...
We use numerical simulations to study the effects of patchiness a partly reionized intergalactic medium (IGM) on observability Ly-alpha emitters (LAEs) at high redshifts (z ~ 6). present new model that divides radiative transfer into (circum-)galactic and an extragalactic part, investigate how choice intrinsic line affects IGM transmission results. our impact neutral hydrogen statistical observables such as restframe equivalent width (REW) distribution, LAE luminosity function two-point...
We present Very Large Telescope/X-shooter spectra of 13 galaxies in the redshift range 1 ≲ z 6, which are strongly lensed by massive galaxy clusters. Spectroscopic redshifts measured for nine galaxies, while three sources have determined from continuum breaks their spectra. The stellar masses span four orders magnitude between 107 and 1011 M⊙ luminosities at 1500 Å rest frame 0.004 9L* after correcting magnification. This allows us to probe a variety types young, low-mass starburst evolved...
We present a detailed study of the emission from z = 2.35 galaxy that causes damped Lyman α absorption in spectrum background quasar (QSO), SDSS J2222−0946. results extensive analyses stellar continuum covering rest frame optical–UV regime based on broad-band Hubble Space Telescope (HST) imaging, and spectroscopy VLT/X-Shooter strong lines: Lyα, [O ii], iii], [N Hα Hβ. compare metallicity lines QSO with oxygen abundance inferred strong-line methods (R23 N2). The two emission-line yield...
It has been suggested that radiative transfer effects may explain the unusually high equivalent widths (EWs) of Lya line, observed occasionally from starburst galaxies, especially at redshifts. If dust is locked up inside high-density clouds dispersed in an empty intercloud medium, photons could scatter off surfaces clouds, effectively having their journey confined to dustless medium. The continuum radiation, on other hand, does not scatter, and would thus be subject absorption clouds. This...
Aims: We aim to study the effects of an inhomogeneous interstellar medium (ISM) on strength and shape Lyman alpha (Lya) line in starburst galaxies. Methods: Using our 3D Monte Carlo Lya radiation transfer code, we radiative Lya, UV optical continuum photons homogeneous clumpy shells neutral hydrogen dust surrounding a central source. Our simulations predict escape fraction, equivalent width EW(Lya), profile their dependence gas geometry main input physical parameters. Results: The ISM...
The first 2 months of spectroscopic and photometric monitoring the nearby Type Ic SN 2007gr are presented. very early discovery (less than 5 days after explosion) relatively short distance host galaxy motivated an extensive observational campaign. shows average peak luminosity but unusually narrow spectral lines almost flat photospheric velocity profile. detection prominent carbon features in spectra is shown suggests a wide range abundance stripped-envelope supernovae. may be important...
A numerical code for solving various Lyα radiative transfer (RT) problems is presented. The suitable an arbitrary, three-dimensional distribution of emissivity, gas temperature, density, and velocity field. Capable handling RT in adaptively refined grid-based structure, it enables detailed investigation the effects clumpiness interstellar (or intergalactic) medium. tested against geometrically physically idealized configurations which analytical solutions exist, subsequently applied to three...