R. A. M. J. Wijers
A5060377458- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- SAS software applications and methods
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- GNSS positioning and interference
- Particle Detector Development and Performance
- Statistical and numerical algorithms
- Cosmology and Gravitation Theories
- Superconducting and THz Device Technology
- Planetary Science and Exploration
- Astrophysics and Star Formation Studies
- Geophysics and Sensor Technology
- Ionosphere and magnetosphere dynamics
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray and CT Imaging
University of Amsterdam
2015-2024
Astronomical Institute of the Slovak Academy of Sciences
2000-2024
Indian Institute of Technology Kanpur
2024
George Washington University
2023
CTA Observatory
2021
The Netherlands Cancer Institute
2005-2018
Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
2016
Amsterdam University of the Arts
2013-2015
University of Wisconsin–Milwaukee
2012
Princeton University
1992-2012
LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in north of Netherlands and across europe. Utilizing novel phased-array design, LOFAR covers largely unexplored low-frequency range from 10-240 MHz provides number unique observing capabilities. Spreading out core located near village Exloo northeast Netherlands, total 40 stations are nearing completion. A further five have been deployed throughout Germany, one station has built each France, Sweden, UK....
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...
The location accuracy of the BeppoSAX Wide Field Cameras and acute ground- based follow-up have led to detection a decaying afterglow in X-rays optical light following classical gamma-ray burst GRB 970228. fades as power law at all wavelengths. This behaviour was predicted for relativistic blast wave that radiates its energy when it decelerates by ploughing into surrounding medium. Because has continued with unchanged more than month, total enegy must be order 1051 erg, placing firmly...
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 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...
We have calculated synchrotron spectra of relativistic blast waves and find predicted characteristic frequencies that are more than an order magnitude different from previous calculations. For the case adiabatically expanding wave, which is applicable to observed gamma-ray burst (GRB) afterglows at late times, we give expressions infer physical properties afterglow measured spectral features. show enough data exist for GRB 970508 compute unambiguously ambient density, n = 0.03 cm-3, wave...
We discuss the afterglows from evolution of both spherical and anisotropic fireballs decelerating in an inhomogeneous external medium. consider radiative adiabatic regimes analyze physical conditions under which these can be used. Afterglows may expected to differ widely among themselves, depending on angular anisotropy fireball properties environment. They entirely absent or detected without a corresponding γ-ray event. A tabulation different representative light curves is presented,...
▪ Abstract The discovery of counterparts in X-ray and optical to radio wavelengths has revolutionized the study γ-ray bursts, until recently most enigmatic astrophysical phenomena. We now know that bursts are biggest explosions nature, caused by ejection ultrarelativistic matter from a powerful energy source its subsequent collision with environment. have just begun uncover connection between supernovae finally constraining properties ultimate burst energy. review here observations led this...
A gamma-ray burst (GRB) releases an amount of energy similar to that a supernova explosion, which combined with its rapid variability suggests origin related neutron stars or black holes. Since these compact stellar remnants form from the most massive not long after their birth, GRBs should trace star formation rate in Universe; we show GRB flux distribution is consistent this. Because strong evolution redshift, it follows dimmest known bursts have z ~ 6, much above value usually quoted and...
We analyze a complete sample of γ-ray burst afterglows and find X-ray evidence for high column densities gas around them. The are in the range 1022-1023 cm-2, which is right average density Galactic giant molecular clouds. also estimate cloud sizes to be 10-30 pc, implying masses ≳105 M☉. This strongly suggests that bursts lie within star-forming regions therefore argues against neutron star mergers collapses massive stars as their sources. optical extinctions, however, 10-100 times smaller...
Low frequency radio waves, while challenging to observe, are a rich source of information about pulsars. The LOw Frequency ARray (LOFAR) is new interferometer operating in the lowest 4 octaves ionospheric "radio window": 10-240MHz, that will greatly facilitate observing pulsars at low frequencies. Through huge collecting area, long baselines, and flexible digital hardware, it expected LOFAR revolutionize astronomy frequencies visible from Earth. next-generation telescope pathfinder Square...
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.