F. Daigne
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View article: EP241021a: A Months-duration X-Ray Transient with Luminous Optical and Radio Emission
EP241021a: A Months-duration X-Ray Transient with Luminous Optical and Radio Emission Open
We present the discovery of a peculiar X-ray transient, EP241021a, by the Einstein Probe (EP) mission and the results from multiwavelength follow-up observations. The transient was first detected with the Wide-field X-ray Telescope as an i…
View article: SVOM GRB 250314A at z $\simeq$ 7.3: an exploding star in the era of reionization
SVOM GRB 250314A at z $\simeq$ 7.3: an exploding star in the era of reionization Open
Most long Gamma-ray bursts originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can be initially extremely luminous at optical/near-infrared wavelengths, making them detectable at large cosmologi…
View article: JWST reveals a supernova following a gamma-ray burst at z $\simeq$ 7.3
JWST reveals a supernova following a gamma-ray burst at z $\simeq$ 7.3 Open
The majority of energetic long-duration gamma-ray bursts (GRBs) are thought to arise from the collapse of massive stars, making them powerful tracers of star formation across cosmic time. Evidence for this origin comes from the presence of…
View article: GRB 221009A and the Apparently Most Energetic Gamma-Ray Bursts
GRB 221009A and the Apparently Most Energetic Gamma-Ray Bursts Open
Gamma-ray bursts (GRBs) are often referred to as the most luminous explosions in the Universe, due to their short and highly luminous prompt emission. This apparent luminosity, however, does not reflect the true energy budget of the prompt…
View article: Gamma-ray burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field
Gamma-ray burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field Open
Context. Synchrotron radiation from accelerated electrons above the photosphere of a relativistic ejecta is a natural candidate for the dominant radiative process for the prompt gamma-ray burst emission. There is, however, a tension betwee…
View article: Very high energy afterglow of structured jets: GW 170817 and prospects for future detections
Very high energy afterglow of structured jets: GW 170817 and prospects for future detections Open
We present a complete numerical model of the afterglow of a laterally structured relativistic ejecta from the radio to very high energies (VHE). This includes a self-consistent calculation of the synchrotron radiation, with its maximum fre…
View article: Gamma-Ray Burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field
Gamma-Ray Burst prompt emission from the synchrotron radiation of relativistic electrons in a rapidly decaying magnetic field Open
Synchrotron radiation from accelerated electrons above the photosphere of a relativistic ejecta is a natural candidate for the dominant process for the prompt GRB emission. There is however a tension between the predicted low-energy spectr…
View article: Multiband analyses of the bright GRB 230812B and the associated SN2023pel
Multiband analyses of the bright GRB 230812B and the associated SN2023pel Open
GRB 230812B is a bright and relatively nearby (z = 0.36) long gamma-ray burst (GRB) that has generated significant interest in the community and has thus been observed over the entire electromagnetic spectrum. We report over 80 observation…
View article: Ending the prompt phase in photospheric models of gamma-ray bursts
Ending the prompt phase in photospheric models of gamma-ray bursts Open
The early steep decay, a rapid decrease in X-ray flux as a function of time following the prompt emission, is a robust feature seen in almost all gamma-ray bursts with early enough X-ray observations. This peculiar phenomenon has often bee…
View article: Ready for O4 II: GRANDMA observations of <i>Swift</i> GRBs over eight weeks in spring 2022
Ready for O4 II: GRANDMA observations of <i>Swift</i> GRBs over eight weeks in spring 2022 Open
Aims. We present a campaign designed to train the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA) network and its infrastructure to follow up on transient alerts and detect their early afterglows. In preparat…
View article: Ready for O4 II: GRANDMA Observations of Swift GRBs during eight-weeks of Spring 2022
Ready for O4 II: GRANDMA Observations of Swift GRBs during eight-weeks of Spring 2022 Open
We present a campaign designed to train the GRANDMA network and its infrastructure to follow up on transient alerts and detect their early afterglows. In preparation for O4 II campaign, we focused on GRB alerts as they are expected to be a…
View article: Ending the prompt phase in photospheric models of gamma-ray bursts
Ending the prompt phase in photospheric models of gamma-ray bursts Open
The early steep decay, a rapid decrease in X-ray flux as a function of time following the prompt emission, is a robust feature seen in almost all gamma-ray bursts with early enough X-ray observations. This peculiar phenomenon has often bee…
View article: Multi-band analyses of the bright GRB 230812B and the associated SN2023pel
Multi-band analyses of the bright GRB 230812B and the associated SN2023pel Open
GRB~230812B is a bright and relatively nearby ($z =0.36$) long gamma-ray burst (GRB) that has generated significant interest in the community and has thus been observed over the entire electromagnetic spectrum. We report over 80 observatio…
View article: The signature of refreshed shocks in the afterglow of GRB 030329
The signature of refreshed shocks in the afterglow of GRB 030329 Open
GRB 030329 displays one clear and, possibly, multiple less intense fast-rising (Δt/t ∼ 0.3) jumps in its optical afterglow light curve. The decay rate of the optical light curve remains the same before and after the flux jumps. This may be…
View article: GRB prompt emission from the synchrotron radiation of relativistic electrons in a decaying magnetic field
GRB prompt emission from the synchrotron radiation of relativistic electrons in a decaying magnetic field Open
The origin of the prompt gamma-ray burst (GRB) emission is still highly debated. The observed spectra provide key constraints: the low energy slope of the photon spectrum $\alpha$, which is commonly determined in energy range of $\sim$ 10 …
View article: Optimization of the <i>SVOM</i> satellite strategy for the rapid follow-up of gravitational wave events
Optimization of the <i>SVOM</i> satellite strategy for the rapid follow-up of gravitational wave events Open
The SVOM satellite, to be launched in early 2024, is primarily devoted to the multiwavelength observation of gamma-ray bursts and other higher-energy transients. Thanks to its onboard Microchannel X-ray Telescope and Visible-band Telescope…
View article: GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann
GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann Open
Object GRB 221009A is the brightest gamma-ray burst (GRB) detected in more than 50 yr of study. In this paper, we present observations in the X-ray and optical domains obtained by the GRANDMA Collaboration and the Insight Collaboration. We…
View article: Optimisation of the SVOM satellite strategy for the rapid follow-up of gravitational wave events
Optimisation of the SVOM satellite strategy for the rapid follow-up of gravitational wave events Open
The SVOM satellite, to be launched in early 2024, is primarily devoted to the multi-wavelength observation of gamma-ray bursts and other higher-energy transients. Thanks to its onboard Microchannel X-ray Telescope and Visible-band Telescop…
View article: Optimisation of the SVOM satellite strategy for the rapid follow-up of\n gravitational wave events
Optimisation of the SVOM satellite strategy for the rapid follow-up of\n gravitational wave events Open
The SVOM satellite, to be launched in early 2024, is primarily devoted to the\nmulti-wavelength observation of gamma-ray bursts and other higher-energy\ntransients. Thanks to its onboard Microchannel X-ray Telescope and Visible-band\nTeles…
View article: Flares in gamma-ray burst X-ray afterglows as prompt emission from slightly misaligned structured jets
Flares in gamma-ray burst X-ray afterglows as prompt emission from slightly misaligned structured jets Open
We develop a model to explain the flaring activity in gamma-ray burst X-ray afterglows within the framework of slightly misaligned observers to structured jets. We suggest that flares could be the manifestation of prompt dissipation within…
View article: The impact of turbulent mixing on the galactic r-process enrichment by binary neutron star mergers
The impact of turbulent mixing on the galactic r-process enrichment by binary neutron star mergers Open
We study the enrichment of the interstellar medium (ISM) with rapid neutron capture (r-process) elements produced in binary neutron star (BNS) mergers. We use a semi-analytic model to describe galactic evolution, with merger rates and time…
View article: The potential role of binary neutron star merger afterglows in multimessenger cosmology
The potential role of binary neutron star merger afterglows in multimessenger cosmology Open
Binary neutron star mergers offer a new and independent means of measuring the Hubble constant H 0 by combining the gravitational-wave inferred source luminosity distance with its redshift obtained from electromagnetic follow-up. This meth…
View article: Prospects for kilonova signals in the gravitational-wave era
Prospects for kilonova signals in the gravitational-wave era Open
The binary neutron star merger gravitational-wave signal GW170817 was followed by three electromagnetic counterparts, including a kilonova arising from the radioactivity of freshly synthesized r -process elements in ejecta from the merger.…
View article: The impact of turbulent mixing on the galactic r-process enrichment by binary neutron star mergers across the entire metallicity range
The impact of turbulent mixing on the galactic r-process enrichment by binary neutron star mergers across the entire metallicity range Open
We study the enrichment of the interstellar medium with rapid neutron capture (r-process) elements produced in binary neutron star (BNS) mergers using a semi-analytic model of the evolution of a Milky-Way-like galaxy in which we implemente…
View article: A new fitting function for GRB MeV spectra based on the internal shock synchrotron model
A new fitting function for GRB MeV spectra based on the internal shock synchrotron model Open
Aims. The physical origin of the gamma-ray burst (GRB) prompt emission is still a subject of debate. Internal shock models have been widely explored, owing to their ability to explain most of the high-energy properties of this emission pha…
View article: The Off-Axis Afterglow of GW170817: Flux Prediction at Very High Energies
The Off-Axis Afterglow of GW170817: Flux Prediction at Very High Energies Open
The binary neutron star merger gravitational-wave event GW170817 and observations of the subsequent electromagnetic signals at different wavelengths have helped better understand the outflows that follow these mergers. In particular, the o…
View article: Probing binary neutron star mergers in dense environments using afterglow counterparts
Probing binary neutron star mergers in dense environments using afterglow counterparts Open
The only binary neutron star merger gravitational wave event with detected electromagnetic counterparts recorded to date is GRB170817A. This merger occurred in a rarefied medium with a density smaller than 10 −3 − 10 −2 cm −3 . Since kicks…
View article: Late X-ray flares from the interaction of a reverse shock with a stratified ejecta in GRB afterglows: simulations on a moving mesh
Late X-ray flares from the interaction of a reverse shock with a stratified ejecta in GRB afterglows: simulations on a moving mesh Open
Late activity of the central engine is often invoked in order to explain the flares observed in the early X-ray afterglow of gamma-ray bursts, either in the form of an active neutron star remnant or (fall-back) accretion on to a black hole…
View article: A new fitting function for GRB MeV spectra based on the internal shock synchrotron model
A new fitting function for GRB MeV spectra based on the internal shock synchrotron model Open
While the Band function or other phenomenological functions are commonly used to fit GRB prompt emission spectra, we propose a new parametric function that is inspired by an internal shock physical model. We use this function as a proxy of…
View article: X-ray plateaus in gamma-ray bursts’ light curves from jets viewed slightly off-axis
X-ray plateaus in gamma-ray bursts’ light curves from jets viewed slightly off-axis Open
Using multiple observational arguments, recent work has shown that cosmological gamma-ray bursts (GRBs) are typically viewed at angles within, or close to the cores of their relativistic jets. One of those arguments relied on the lack of t…