K. Wiersema
A5000947923- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Advanced X-ray and CT Imaging
- Atmospheric and Environmental Gas Dynamics
- Adaptive optics and wavefront sensing
- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Computational Fluid Dynamics and Aerodynamics
- Photocathodes and Microchannel Plates
- Advanced X-ray Imaging Techniques
- Calibration and Measurement Techniques
- Particle Accelerators and Free-Electron Lasers
- History and Developments in Astronomy
University of Hertfordshire
2023-2025
University of Washington
2025
University of Leicester
2015-2024
Lancaster University
2022-2024
University of Warwick
2017-2023
ORCID
2021
Centrum Badań Kosmicznych
2018
Polish Academy of Sciences
2018
University of Southampton
2017
University of Amsterdam
2003-2013
We present a homogeneous X-ray analysis of all 318 gamma-ray bursts detected by the telescope (XRT) on Swift satellite up to 2008 July 23; this represents largest sample GRB data published date. In Sections 2–3, we detail methods which Swift-XRT team has developed produce enhanced positions, light curves, hardness ratios and spectra presented in paper. Software using these continues create such products for new GRBs observed Swift-XRT. also web-based tools allowing users any object XRT, not...
Abstract We report the discovery and monitoring of near-infrared counterpart (AT2017gfo) a binary neutron-star merger event detected as gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) short gamma-ray burst Fermi Gamma-ray Burst Monitor (GBM) Integral SPI-ACS (GRB 170817A). The evolution transient light is consistent with predictions for behavior “kilonova/macronova” powered radioactive decay massive neutron-rich nuclides...
Gamma-ray bursts (GRBs) serve as powerful probes of the early Universe, with their luminous afterglows revealing locations and physical properties star forming galaxies at highest redshifts, potentially locating first generation (Population III) stars. Since GRB have intrinsically very simple spectra, they allow robust redshifts from low signal to noise spectroscopy, or photometry. Here we present a photometric redshift z~9.4 for Swift-detected 090429B based on deep observations...
Variable X-ray and gamma-ray emission is characteristic of the most extreme physical processes in Universe, studying sources these energetic photons has been a major driver astronomy for past 50 years. Here we present multiwavelength observations unique selected transient, discovered by Swift, which was accompanied bright across electromagnetic spectrum, whose properties are unlike any previously observed source. We pinpoint event to center small, star-forming galaxy at redshift z=0.3534....
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...
(Abridged). We present a sample of 77 optical afterglows (OAs) Swift detected GRBs for which spectroscopic follow-up observations have been secured. provide linelists and equivalent widths all lines redward Ly-alpha. discuss to what extent the current bursts with OA spectroscopy is biased subsample GRBs. For that purpose we define an X-ray selected optimal conditions ground-based follow up from period March 2005 September 2008; 146 fulfill our criteria. derive redshift distribution this...
We present comprehensive multiwavelength observations of three gamma-ray bursts (GRBs) with durations several thousand seconds. demonstrate that these events are extragalactic transients; in particular we resolve the long-standing conundrum distance GRB 101225A (the "Christmas-day burst"), finding it to have a redshift z=0.847, and showing two apparently similar (GRB 111209A 121027A) lie at z=0.677 z=1.773 respectively. The systems show extremely unusual X-ray optical lightcurves, very...
Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" "long/soft." The latter conclusively linked to explosive deaths massive stars, while former are thought result from merger or collapse compact objects. In recent years, indications accumulating that short/hard versus long/soft division does not map directly onto what would be expected classes progenitors, leading a new classification scheme Type I...
We present multiwavelength observations of the afterglow GRB 130427A, brightest (in total fluence) gamma-ray burst (GRB) past 29 yr. Optical spectroscopy from Gemini-North reveals redshift to be z = 0.340, indicating that its unprecedented brightness is primarily result relatively close proximity Earth; intrinsic luminosities both and are not extreme in comparison other bright GRBs. a large suite spanning 300 s 130 days after demonstrate shows simple, smooth evolution at all frequencies,...
We present observations of the optical afterglow GRB\,170817A, made by {\it Hubble Space Telescope}, between February and August 2018, up to one year after neutron star merger, GW170817. The shows a rapid decline beyond $170$~days, confirms jet origin for observed outflow, in contrast more slowly declining expectations `failed-jet' scenarios. show here that broadband (radio, optical, X-ray) is consistent with structured outflow where an ultra-relativistic jet, Lorentz factor...
We report on the detection by Swift of GRB 080913, and subsequent optical/near-infrared follow-up observations GROND, which led to discovery its optical/NIR afterglow recognition high-z nature via a spectral break between i' z' bands. Spectroscopy obtained at ESO-VLT revealed continuum extending down λ = 9400 Å, zero flux for 7500 Å<λ < we interpret as onset Gunn–Peterson trough z 6.695± 0.025 (95.5% confidence level), making 080913 highest-redshift gamma-ray burst (GRB) date, more distant...
Aims.We present early optical spectroscopy of the afterglow gamma-ray burst GRB 060206 with aim determining metallicity absorber and physical conditions in circumburst medium. We also discuss how GRBs may be important complementary probes cosmic chemical evolution.
We present data and initial results from VLT/X-Shooter emission-line spectroscopy of 96 galaxies selected by long γ-ray bursts (GRBs) at 0.1 <z< 3.6, the largest sample GRB host spectra available to date. Most our GRBs were detected Swift 76% are 0.5 2.5 with a median zmed ~ 1.6. Based on Balmer and/or forbidden lines oxygen, nitrogen, neon, we measure systemic redshifts, star formation rates (SFR), visual attenuations (AV), oxygen abundances (12 + log (O/H)), widths (σ). study hosts up z...
We report the Swift discovery of nearby long, soft gamma-ray burst GRB 100316D, and subsequent unveiling its low redshift host galaxy associated supernova. derive event to be z = 0.0591 +/- 0.0001 provide accurate astrometry for GRB-SN. study extremely unusual prompt emission with time-resolved X-ray spectroscopy, find that spectrum is best modelled a thermal component in addition synchrotron peak energy. The light curve has remarkably shallow decay out at least 800 s. bright, blue highly...
Abstract We present Hubble Space Telescope ( HST ) and Chandra imaging, combined with Very Large MUSE integral field spectroscopy of the counterpart host galaxy first binary neutron star merger detected via gravitational-wave emission by LIGO Virgo, GW170817. The galaxy, NGC 4993, is an S0 at z = 0.009783. There evidence for large, face-on spiral shells in continuum edge-on features visible nebular lines. This suggests that 4993 has undergone a relatively recent <mml:math...
Abstract We report our identification of the optical afterglow and host galaxy short-duration gamma-ray burst sGRB 160821B. The spectroscopic redshift is z = 0.162, making it one lowest bursts (sGRBs) identified by Swift . Our intensive follow-up campaign using a range ground-based facilities as well Hubble Space Telescope , XMM-Newton shows evidence for late-time excess near-infrared emission in addition to complex afterglow. light curve at X-ray frequencies reveals narrow jet, <?CDATA...
We present the discovery of fast infrared/X-ray correlated variability in black-hole transient GX 339-4. The source was observed with sub-second time resolution simultaneously VLT/ISAAC and RXTE/PCA August 2008, during its persistent low-flux highly variable hard state. data show a strong variability, infrared emission lagging X-ray by 100 ms. short delay nearly symmetric cross-correlation function, together measured brightness temperature ~2.5 x 10^6 K, indicate that bright most likely...
Long-duration Gamma-Ray Bursts (GRBs) are an extremely rare outcome of the collapse massive stars, and typically found in distant Universe. Because its intrinsic luminosity ($L\sim 3 \times 10^{53}$ erg s$^{-1}$) relative proximity ($z=0.34$), GRB 130427A was a unique event that reached highest fluence observed gamma-ray band. Here we present comprehensive multiwavelength view with Swift, 2-m Liverpool Faulkes telescopes by other ground-based facilities, highlighting evolution burst emission...
ABSTRACT We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (“SHOALS”), a multi-observatory high-redshift galaxy survey targeting largest unbiased sample of long-duration gamma-ray burst (GRB) hosts yet assembled (119 in total). describe motivations and development our selection criteria, including an assessment impact various observability metrics on success rate afterglow-based redshift measurement. briefly outline host observational program, consisting deep Spitzer /IRAC...