Christoffer Lundman
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View article: Radiation-mediated shocks in GRB prompt emission
Radiation-mediated shocks in GRB prompt emission Open
The debate regarding the emission mechanism in gamma-ray bursts has been long-standing. Here, we study the spectral signatures of photospheric emission, accounting for subphotospheric dissipation by a radiation-mediated shock. The shocks a…
View article: Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule Them All
Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule Them All Open
Using the resultant profiles from 3D hydrodynamic simulations of relativistic jets interacting with neutron star merger wind ejecta, we show how the inhomogeneity of energy and velocity across the jet surface profile can alter the observed…
View article: Onset of Particle Acceleration during the Prompt Phase in Gamma-Ray Bursts as Revealed by Synchrotron Emission in GRB 160821A
Onset of Particle Acceleration during the Prompt Phase in Gamma-Ray Bursts as Revealed by Synchrotron Emission in GRB 160821A Open
The physical processes of gamma-ray emission and particle acceleration during the prompt phase in gamma-ray bursts (GRBs) are still unsettled. In order to perform unambiguous physical modeling of observations, a clear identification of the…
View article: Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule them all
Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule them all Open
Using the resultant profiles from 3D hydrodynamic simulations of relativistic jets interacting with neutron star merger wind ejecta, we show how the inhomogeneity of energy and velocity {across the jet surface profile} can alter the observ…
View article: An Efficient Method for Fitting Radiation-mediated Shocks to Gamma-Ray Burst Data: The Kompaneets RMS Approximation
An Efficient Method for Fitting Radiation-mediated Shocks to Gamma-Ray Burst Data: The Kompaneets RMS Approximation Open
Shocks that occur below a gamma-ray burst (GRB) jet photosphere are mediated by radiation. Such radiation-mediated shocks (RMSs) could be responsible for shaping the prompt GRB emission. Although well studied theoretically, RMS models have…
View article: An efficient method for fitting radiation-mediated shocks to gamma-ray burst data: The Kompaneets RMS approximation
An efficient method for fitting radiation-mediated shocks to gamma-ray burst data: The Kompaneets RMS approximation Open
Shocks that occur below a gamma-ray burst (GRB) jet photosphere are mediated by radiation. Such radiation-mediated shocks (RMSs) could be responsible for shaping the prompt GRB emission. Although well studied theoretically, RMS models have…
View article: Are interactions with neutron star merger winds shaping the jets?
Are interactions with neutron star merger winds shaping the jets? Open
Jets can become collimated as they propagate through dense environments and understanding such interactions is crucial for linking physical models of the environments to observations. In this work, we use 3D special-relativistic simulation…
View article: Calibration of the Advanced Spectral Leakage scheme for neutron star merger simulations, and extension to smoothed-particle hydrodynamics
Calibration of the Advanced Spectral Leakage scheme for neutron star merger simulations, and extension to smoothed-particle hydrodynamics Open
We calibrate a neutrino transport approximation, called Advanced Spectral Leakage (ASL), with the purpose of modelling neutrino-driven winds in neutron star mergers. Based on a number of snapshots, we gauge the ASL parameters by comparing …
View article: Extension of the Advanced Spectral Leakage scheme for neutron star merger simulations
Extension of the Advanced Spectral Leakage scheme for neutron star merger simulations Open
We extend a neutrino transport approximation, called Advanced Spectral Leakage (ASL), with the purpose of modeling neutrino-driven winds in neutron star mergers. Based on a number of snapshots we gauge the ASL parameters by comparing again…
View article: A First-principle Simulation of Blast-wave Emergence at the Photosphere of a Neutron Star Merger
A First-principle Simulation of Blast-wave Emergence at the Photosphere of a Neutron Star Merger Open
We present the first ab initio simulation of a radiation-mediated shock emerging at the photosphere of a relativistic outflow. The simulation is performed using our code radshock that follows fluid dynamics coupled to time-dependent radiat…
View article: Can jets make the radioactively powered emission from neutron star mergers bluer?
Can jets make the radioactively powered emission from neutron star mergers bluer? Open
Neutron star mergers eject neutron-rich matter in which heavy elements are synthesized. The decay of these freshly synthesized elements powers electromagnetic transients (‘macronovae’ or ‘kilonovae’) whose luminosity and colour strongly de…
View article: Consequences of Jet-Ejecta Interaction in Neutron Star Mergers
Consequences of Jet-Ejecta Interaction in Neutron Star Mergers Open
In the first observed neutron star merger, GW170817, two dynamical components, mildly- and ultra-relativistic outflows were detected independently. The first component triggered a rapidly evolving thermal transient named macronova (kilonov…
View article: Testing a model for subphotospheric dissipation in GRBs: fits to Fermi data constrain the dissipation scenario
Testing a model for subphotospheric dissipation in GRBs: fits to Fermi data constrain the dissipation scenario Open
It has been suggested that the prompt emission in gamma-ray bursts (GRBs) could be described by radiation from the photosphere in a hot fireball. Such models must be tested by directly fitting them to data. In this work we use data from th…
View article: On the α–intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy
On the α–intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy Open
The emission mechanism during the prompt phase in gamma-ray bursts (GRBs) can be investigated through correlations between spectral properties. Here, we revisit the correlation relating the instantaneous flux, $F$, and the photon index bel…
View article: Polarization of Gamma-Ray Bursts in the Dissipative Photosphere Model
Polarization of Gamma-Ray Bursts in the Dissipative Photosphere Model Open
The MeV spectral peak of gamma-ray bursts (GRBs) is best explained as photospheric emission from a dissipative relativistic jet. The observed non-blackbody spectrum shows that sub-photospheric dissipation involves both thermal plasma heati…
View article: Emission from accelerating jets in gamma-ray bursts: radiation-dominated flows with increasing mass outflow rates
Emission from accelerating jets in gamma-ray bursts: radiation-dominated flows with increasing mass outflow rates Open
We study the narrowest spectra expected from gamma-ray bursts. We present an analytical function for the spectrum that is emitted from the photosphere of a radiation-dominated flow that is under acceleration. This is the narrowest possible…
View article: Extremely narrow spectrum of GRB110920A: further evidence for localized, subphotospheric dissipation
Extremely narrow spectrum of GRB110920A: further evidence for localized, subphotospheric dissipation Open
Much evidence points towards that the photosphere in the relativistic outflow in GRBs plays an important role in shaping the observed MeV spectrum. However, it is unclear whether the spectrum is fully produced by the photosphere or whether…
View article: Extremely narrow spectrum of GRB110920A: further evidence for localised, subphotospheric dissipation
Extremely narrow spectrum of GRB110920A: further evidence for localised, subphotospheric dissipation Open
Much evidence points towards that the photosphere in the relativistic outflow in GRBs plays an important role in shaping the observed MeV spectrum. However, it is unclear whether the spectrum is fully produced by the photosphere or whether…