A5083305122- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Atmospheric Ozone and Climate
- Astrophysics and Star Formation Studies
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Microbial Metabolites in Food Biotechnology
- Solar and Space Plasma Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Statistical and numerical algorithms
- Planetary Science and Exploration
- Advanced X-ray and CT Imaging
- Dark Matter and Cosmic Phenomena
- Spectroscopy Techniques in Biomedical and Chemical Research
University of Bath
2019-2025
Max Planck Institute for Extraterrestrial Physics
2012-2023
Polish Academy of Sciences
2018
Centrum Badań Kosmicznych
2018
Max Planck Society
2010-2017
Google (United States)
2017
UCL Australia
2006-2013
University College London
2005-2011
Pennsylvania State University
2005-2011
Brera Astronomical Observatory
2011
We present the photometric calibration of Swift UltraViolet/Optical Telescope (UVOT) which includes: optimum and background apertures, effective area curves, colour transformations, conversion factors for count rates to flux, zero points (which are accurate better than 4 per cent) each seven UVOT broadband filters. The was performed with observations standard stars star fields that represent a wide range spectral types. results include position dependent uniformity, instrument response over...
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...
(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...
The light emitted by stars and accreting compact objects through the history of Universe is encoded in intensity extragalactic background (EBL). Knowledge EBL important to understand nature star formation galaxy evolution, but direct measurements are lim- ited Galactic other foreground emissions. Here we report an absorption feature seen combined spectra a sample gamma-ray blazars out redshift z$\sim$1.6. This caused attenuation gamma rays at optical UV frequencies, allowed us measure flux...
We present the ATLAS discovery and initial analysis of first 18 days unusual transient event, ATLAS18qqn/AT2018cow. It is characterized by a high peak luminosity ($\sim$1.7 $\times$ 10$^{44}$ erg s$^{-1}$), rapidly evolving light curves ($>$5 mag rise to in $\sim$3.5 days), hot blackbody spectra, peaking at $\sim$27000 K that are relatively featureless unchanging over two weeks. The bolometric curve cannot be powered radioactive decay under realistic assumptions. detection high-energy...
We systematically analyze the prompt emission and early afterglow data of a sample 31 GRBs detected by {\em Swift} before September 2005, estimate GRB radiative efficiency. BAT's narrow band inhibits precise determination spectral parameters, we have developed method to these parameters with hardness ratio information. The shallow decay component commonly existing in X-ray afterglows, if interpreted as continuous energy injection external shock, suggests that efficiency previously derived...
The Ultraviolet/Optical Telescope (UVOT) is one of three instruments onboard the Swift observatory. photometric calibration has been published, and this paper follows up with details on other aspects including a measurement point spread function an assessment orbital variation effect photometry. A correction for large-scale variations in sensitivity over field view described, as well model coincidence loss which used to assess extended regions. We have provided detector distortion measured...
We present a detailed analysis of Swift multi-wavelength observations GRB 070110 and its remarkable afterglow. The early X-ray light curve, interpreted as the tail prompt emission, displays spectral evolution already seen in other gamma-ray bursts. optical afterglow shows shallow decay up to ~2 d after burst, which is not consistent with standard models. most intriguing feature very steep flux at ~20 ks ending an apparent plateau. abrupt drop curve rules out external shock origin plateau...
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...
Context. Thirteen years after the discovery of first afterglows, nature dark gamma-ray bursts (GRB) still eludes explanation: while each long-duration GRB typically has an X-ray afterglow, optical/NIR emission is only seen for 40–60% them.
(Abridged) Until recently the information inferred from gamma-ray burst follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Here, we present GRB afterglow and host for a sample bursts are exemplary previously missed ones because high visual extinction along sight-line. This facilitates an investigation properties, geometry location absorbing dust these poorly-explored galaxies,...
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...
Fermi has provided the largest sample of γ-ray-selected blazars to date. In this work we use a uniformly selected set 211 BL Lacertae (BL Lac) objects detected by during its first year operation. We obtained redshift constraints for 206 out Lac in our sample, making it and most complete available literature. determine luminosity function evolution with cosmic time. find that classes is positive, space density peaking at modest (z ≈ 1.2). Low-luminosity, high-synchrotron–peaked (HSP) are an...
We present the observations of GRB090510 performed by Fermi Gamma-Ray Space Telescope and Swift observatory. This is a bright, short burst that shows an extended emission detected in GeV range. Furthermore, its optical initially rises, feature so far observed only long bursts, while X-ray flux initial shallow decrease, followed steeper decay. exceptional behavior enables us to investigate physical properties GRB outflow, poorly known bursts. discuss internal shock external models for...
Motivated by the anomalous dust-to-metal ratios derived in literature for γ-ray burst (GRB) damped Lyman-α absorbers (DLAs), we measure these using dust-depletion pattern observed UV/optical afterglow spectra associated with interstellar medium (ISM) at GRB host-galaxy redshifts. Our sample consists of 20 and a comparison 72 DLAs toward quasars (QSOs) redshift 1.2 < z 4.0 down to Z = 0.002 Z⊙ metallicities. The ratio QSO- GRB-DLAs increases both metallicity metal column density, spanning...