D. Bersier
A5054951883- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- SAS software applications and methods
- Astrophysical Phenomena and Observations
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Nuclear reactor physics and engineering
- Neutrino Physics Research
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Particle Detector Development and Performance
- Calibration and Measurement Techniques
- Crystal Structures and Properties
- Catalysis and Oxidation Reactions
- Computational Physics and Python Applications
Liverpool John Moores University
2014-2023
Brera Astronomical Observatory
2007-2009
University of Ljubljana
2007-2009
Herzberg Institute of Astrophysics
2009
Dominion Astrophysical Observatory
2009
Nicolaus Copernicus Astronomical Center
2009
The Ohio State University
2009
Institut d'Astrophysique de Paris
2009
Center for Astrophysics Harvard & Smithsonian
2002-2009
The University of Melbourne
2009
We present early observations of the afterglow GRB 030329 and spectroscopic discovery its associated supernova SN 2003dh. obtained spectra each night from March 30.12 (0.6 days after burst) to April 8.13 (UT) (9.6 burst). The cover a wavelength range 350-850 nm. consist power-law continuum (Fν ∝ ν-0.9) with narrow emission lines originating H II regions in host galaxy, indicating low redshift z = 0.1687. However, our taken 2003 5 show broad peaks flux characteristic supernova. Correcting for...
Literature data are collated for 38 stripped-envelope core-collapse supernovae (SE SNe; i.e. SNe IIb, Ib, Ic and Ic-BL) that have good light curve coverage in more than one optical band. Using bolometric corrections derived previous work, the of each SN is recovered template curves provided. Peak distributions decay rates investigated; subtypes not cleanly distinguished this parameter space, although some grouping types does occur there a suggestion Phillips-like relation most Ic-BL. The...
We present ground-based and Swift photometric spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at center PGC 043234 ($d\simeq90$ Mpc) by All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity $L\simeq10^{44}$ ergs s$^{-1}$ total integrated energy $E\simeq7\times10^{50}$ radiated over $\sim6$ months presented. UV/optical emission is well-fit blackbody with roughly constant temperature $T\sim35,000$ K, while...
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...
ASASSN-14ae is a candidate tidal disruption event (TDE) found at the center of SDSS J110840.11+340552.2 ($d\simeq200$~Mpc) by All-Sky Automated Survey for Supernovae (ASAS-SN). We present ground-based and Swift follow-up photometric spectroscopic observations source, finding that transient had peak luminosity $L\simeq8\times10^{43}$~erg~s$^{-1}$ total integrated energy $E\simeq1.7\times10^{50}$ ergs radiated over $\sim5$ months presented. The blackbody temperature remains roughly constant...
We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as most luminous supernova yet found. At redshift z = 0.2326, reached an absolute magnitude M_{u,AB} -23.5+/-0.1 and bolometric luminosity L_bol (2.2+/-0.2)x 10^45 ergs s^-1, is more than twice any previously known supernova. It has several major features characteristic hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources progenitors are currently poorly understood. In contrast to SLSNe-I that reside in...
The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and products which are publicly available through ESO archive Data Release 1 (SSDR1). PESSTO uses New Technology Telescope with EFOSC2 SOFI to provide optical NIR spectroscopy imaging. target supernovae transients brighter than 20.5mag for classification. Science targets then selected follow-up based on...
Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −18), blue transients. While commonly attributed the breakout a supernova shock into dense wind, great distances transients this class found so far hampered detailed investigation their properties. We present photometry and spectroscopy from comprehensive worldwide campaign observe AT 2018cow (ATLAS 18qqn), first fast-luminous transient be in real time at low redshift. Our spectra (<2 days...
The universality of the Cepheid Period-Luminosity relations has been under discussion since metallicity effects have assumed to play a role in value intercept and, more recently, slope these relations. goal present study is calibrate Galactic PL various photometric bands (from B K) and compare results well-established LMC. We use set 59 calibrating stars, distances which are measured using five different distance indicators: Hubble Space Telescope revised Hipparcos parallaxes, infrared...
We present initial results from a time-series BVI survey of two fields in NGC 4258 using the Advanced Camera for Surveys onboard Hubble Space Telescope. This galaxy was selected because its accurate maser-based distance, which is anticipated to have total uncertainty ~3%. The goal HST observations provide an absolute calibration Cepheid Distance Scale and measure dependence on chemical abundance (the so-called "metallicity effect"). carried out at different galactocentric distances with mean...
We present extensive optical and infrared photometry of the afterglow gamma-ray burst (GRB) 030329 its associated supernova (SN) 2003dh over first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety telescopes is shown and, when combined with photometry, allows an unambiguous separation between SN contributions. The GRB initially power-law continuum but shows significant color variations during week that are unrelated to presence SN. early light curve...
On May 31, 2011 UT a supernova (SN) exploded in the nearby galaxy M51 (the Whirlpool Galaxy). We discovered this event using small telescopes equipped with CCD cameras, as well by Palomar Transient Factory (PTF) survey, and rapidly confirmed it to be Type II supernova. Our early light curve spectroscopy indicates that PTF11eon resulted from explosion of relatively compact progenitor star evidenced rapid shock-breakout cooling seen curve, low temperature early-time spectra prompt appearance...
A number of studies abundance gradients in the galactic disk have been performed recent years. The results obtained are rather disparate: from no detectable gradient to a significant slope about -0.1 dex kpc-1. present study concerns based on spectroscopic analysis sample classical Cepheids. These stars enable one obtain reliable abundances variety chemical elements. Additionally, they well determined distances which allow an accurate determination distributions disc. Using 236 high...
We assemble a sample of 24 hydrogen-poor super-luminous supernovae (SLSNe). Parameterizing the light curve shape through rise and decline timescales shows that two are highly correlated. Magnetar-powered models can reproduce correlation, with diversity in rates driven by diffusion timescale. Circumstellar interaction exhibit similar rise-decline relation, but only for narrow range densities, which may be problematic these models. find SLSNe approximately 3.5 magnitudes brighter have curves 3...
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...
We present ground-based and Swift photometric spectroscopic observations of the tidal disruption event (TDE) ASASSN-15oi, discovered at centre 2MASX J20390918−3045201 (d ≃ 216 Mpc) by All-Sky Automated Survey for SuperNovae. The source peaked a bolometric luminosity L 1.3 × 1044 erg s−1 radiated total energy E 6.6 1050 over first ∼3.5 months observations. early optical/UV emission can be fit blackbody with temperature increasing from T ∼ 2 104 K to 4 while declines 2.3 1043 s−1, requiring...
The nearby Type Ia supernova (SN Ia) SN 2011fe in M101 (cz = 241 km s−1) provides a unique opportunity to study the early evolution of "normal" Ia, its compositional structure, and elusive progenitor system. We present 18 high signal-to-noise spectra during first month beginning 1.2 days post-explosion with an average cadence 1.8 days. This gives clear picture how various line-forming species are distributed within outer layers ejecta, including that unburned material (C+O). follow C ii...
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...
We present observations and analysis of 18 stripped-envelope supernovae observed during 2013–2018. This sample consists five H/He-rich SNe, six H-poor/He-rich three narrow lined SNe Ic, four broad Ic. The peak luminosity characteristic time-scales the bolometric light curves are calculated, modelled to derive 56Ni ejecta masses (MNi Mej). Additionally, temperature evolution spectral line velocity each SN examined. Analysis [O i] in nebular phase eight suggests their progenitors had initial...
A key tracer of the elusive progenitor systems Type Ia supernovae (SNe Ia) is detection narrow blueshifted time-varying Na i D absorption lines, interpreted as evidence circumstellar material surrounding system. The origin this controversial, but simplest explanation that it results from previous mass-loss in a system containing white dwarf and non-degenerate companion star. We present new single-epoch intermediate-resolution spectra 17 low-redshift SNe taken with XShooter on European...
We present the first direct distance determination to a detached eclipsing binary in M33, which was found by DIRECT Project. Located OB 66 association at coordinates (alpha, delta)=(01:33:46.17,+30:44:39.9) for J2000.0, it one of most suitable binaries determination, given its apparent magnitude and orbital period. obtained follow-up BV time series photometry, JHKs photometry optical spectroscopy from we determined parameters system. It contains two O7 main sequence stars with masses...
We present the discovery and follow-up observations of afterglow gamma-ray burst GRB 011121 its associated supernova SN 2001ke. Images were obtained with Optical Gravitational Lensing Experiment 1.3 m telescope in BVRI passbands, starting 10.3 hr after burst. The temporal analysis our early data indicates a steep decay, independent wavelength, Fν ∝ t-1.72±0.05. There is no evidence for break light curve earlier than 2.5 days spectral energy distribution determined from broadband photometry...