A. J. Levan
A5025740124- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Geophysics and Gravity Measurements
- Astrophysics and Star Formation Studies
- Particle Detector Development and Performance
- Solar and Space Plasma Dynamics
- Advanced X-ray and CT Imaging
- Particle Accelerators and Free-Electron Lasers
- Spectroscopy and Chemometric Analyses
- Methane Hydrates and Related Phenomena
- Microbial Metabolites in Food Biotechnology
- Cosmology and Gravitation Theories
- Planetary Science and Exploration
- CCD and CMOS Imaging Sensors
- Nuclear Physics and Applications
- Optical Systems and Laser Technology
University of Warwick
2016-2025
Radboud University Nijmegen
2019-2025
Columbia University
2021
Pennsylvania State University
2021
George Washington University
2021
University of Washington
2005-2012
Lund University
2006-2011
University of Hertfordshire
2005-2010
University of Copenhagen
2010
Excellence Cluster Universe
2010
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...
While gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, vast majority MBHs are considered dormant. Occasionally, a star passing too near MBH is torn apart by gravitational forces, leading to bright panchromatic tidal disruption flare (TDF). high-energy transient Swift J164449.3+573451 ("Sw 1644+57") initially displayed none theoretically anticipated (nor previously observed) TDF characteristics, we show that observations (Levan...
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...
A significant fraction of the Long Gamma-ray Bursts (LGRBs) in Swift sample have a plateau phase showing evidence ongoing energy injection. We suggest that many Short (SGRBs) detected by satellite also show Explaining this observation within typical SGRB progenitor model is challenging as late time accretion, often used to explain plateaus LGRBs, likely be absent from population. Alternatively, it predicted remnant NS-NS mergers may not collapse immediately BH (or even at all), forming...
We report the discovery by Swift hard X-ray monitor of transient source J2058.4+0516 (Sw J2058+05). Our multi-wavelength follow-up campaign uncovered a long-lived (duration ≳ months), luminous (LX, iso ≈ 3 × 1047 erg s−1) and radio (νLν, 1042 counterpart. The associated optical emission, however, from which we measure redshift 1.1853, is relatively faint, this not due to large amount dust extinction in host galaxy. Based on numerous similarities with recently discovered GRB 110328A/Swift...
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...
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...
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 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...
The mergers of binary compact objects such as neutron stars and black holes are central interest to several areas astrophysics, including the progenitors gamma-ray bursts (GRBs), sources high-frequency gravitational waves likely production sites for heavy element nucleosynthesis via rapid capture (the r-process). These elements include some great geophysical, biological cultural importance, thorium, iodine gold. Here we present observations exceptionally bright burst GRB 230307A. We show...
Abstract We present a comprehensive optical and near-infrared census of the fields 90 short gamma-ray bursts (GRBs) discovered in 2005–2021, constituting all GRBs for which host galaxy associations are feasible (≈60% total Swift GRB population). contribute 274 new multi-band imaging observations across 58 distinct 26 spectra their galaxies. Supplemented by literature archival survey data, catalog contains 542 photometric 42 spectroscopic data sets. The reaches 3 σ depths ≳24–27 mag ≳23–26...