The long rapid decay phase of the extended emission from the short GRB 080503 (2009)
Genet, Franck, Butler, Nathaniel R., Granot, Jonathan
GRB080503 was classified as a short GRB with extended emission (Perley et al. 2009). The origin of such extended emission (found in about a quarter of Swift short GRBs) is still unclear and may...
Kocevski, Daniel, Thone, Christina C, Ramirez-Ruiz, Enrico, Bloom, Joshua S., Granot, Jonathan, Butler, Nathaniel R., ...
We present results of an extensive observing campaign of the short duration, hard spectrum gamma-ray burst (GRB) 070724A, aimed at detecting the radioactively-powered emission that might follow from...
GRB Theory in the Fermi Era (2009)
Granot, Jonathan, LAT, For The Fermi, Collaborations, GBM
Before the launch of the Fermi Gamma-ray Space Telescope there were only a handful of gamma-ray bursts (GRBs) detected at high energies (above 100 MeV), while several different suggestions have been...
Late time observations of GRB080319B: jet break, host galaxy and accompanying supernova (2008)
Tanvir, Nial R., Rol, Evert, Levan, Andrew, Fruchter, Andrew, Granot, Jonathan, Svensson, Karl M., ...
The Swift-discovered GRB080319B was by far the most distant source ever observed at naked eye brightness, reaching a peak magnitude of 5.3 at a redshift of z=0.937. We present our late time optical...
Analytic Expressions for the Surface Brightness Profile of GRB Afterglow Images (2008)
The exact profile of a gamma-ray burst (GRB) afterglow image on the plane of the sky can provide important constraints on the underlying physics. In particular, it can test whether the magnetic field...
Critical Review of Basic Afterglow Concepts (2008)
The long lived afterglow emission that follows gamma-ray bursts (GRBs) was predicted prior to its detection in 1997, in the X-rays, optical and radio. It is thought to arise from the shock that is...
Broadband observations of the naked-eye y-ray burst GRB 080319B (2008)
Racusin, Judith L., Karpov, S. V., Sokolowski, M., Granot, Jonathan, Wu, Xiao Feng, Pal'shin, V., ...
Long-duration y-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of...
Broadband observations of the naked-eye y-ray burst GRB 080319B (2008)
Racusin, Judith L., Karpov, S. V., Sokolowski, M., Granot, Jonathan, Wu, Xiao Feng, Pal'shin, V., ...
Long-duration y-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of...
Smooth light curves from a bumpy ride: relativistic blast wave encounters a density jump (2007)
In the standard forward shock model for gamma-ray burst (GRB) afterglow, the observed afterglow emission is synchrotron radiation from a quasi-spherical, adiabatic, self-similar, relativistic blast...
Opacity Build-up in Impulsive Relativistic Sources (2007)
Granot, Jonathan, Cohen-Tanugi, Johann
Opacity effects in relativistic sources of high-energy gamma-rays, such as gamma-ray bursts (GRBs) or Blazars, can probe the Lorentz factor of the outflow and the distance of the emission site from...
The Structure and Dynamics of GRB Jets (2007)
There are several lines of evidence which suggest that the relativistic out flows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true...
The flat decay phase in the early X-ray afterglows of Swift GRBs (2006)
Many Swift GRBs show an early phase of shallow decay in their X-ray afterglows, lasting from $t \sim 10^{2.5} $s to $\sim 10^4 $s after the GRB, where the flux decays as $\sim t^{-0.2}-t^{-0.8}$....
The Structure and Dynamics of GRB Jets (2006)
There are several lines of evidence which suggest that the relativistic outflows in gamma-ray bursts (GRBs) are collimated into narrow jets. The jet structure has important implications for the true...
A Simple Test of the External Shock Model for the Prompt Emission in Gamma-Ray Bursts (2006)
Ramirez-Ruiz, Enrico, Granot, Jonathan
It is demonstrated here that if the prompt GRB emission is produced by the simplest version of the external shock model, a specific relation should prevail between the observed duration, isotropic...
Smooth Light Curves from a Bumpy Ride: Relativistic Blast Wave Encounters a Density Jump (2006)
Some GRB afterglow light curves show significant variability, which often includes episodes of rebrightening. This was attributed in several cases to large fluctuations in the external density. Here...
Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs (2006)
Granot, Jonathan, Konigl, Arieh, Piran, Tsvi
According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process,...
Distribution of Gamma-ray Burst Ejecta Energy with Lorentz Factor (2005)
Granot, Jonathan, Kumar, Pawan
The early X-ray afterglow for a significant number of gamma-ray bursts detected by the Swift satellite is observed to have a phase of very slow flux decline with time ($F_\nu \propto t^{-\alpha}$...
The Case for Anisotropic Afterglow Efficiency within Gamma-Ray Burst Jets (2005)
Eichler, David, Granot, Jonathan
Early X-ray afterglows recently detected by {\it Swift} frequently show a phase of very shallow flux decay lasting from $\sim 10^{2.5} $s up to $\sim 10^4 $s, followed by a steeper, more familiar...
A compact binary merger model for the short, hard GRB 050509b (2005)
Lee, William H., Ramirez-Ruiz, Enrico, Granot, Jonathan
The first X-ray afterglow for a short (~30 ms), hard gamma-ray burst was detected by Swift on 9 May 2005 (GRB 050509b). No optical or radio counterpart was identified in follow-up observations. The...
Afterglow Light Curves from Impulsive Relativistic Jets with an Unconventional Structure (2005)
The jet structure in gamma-ray burst (GRB) sources is still largely an open question. The leading models invoke either (i) a roughly uniform jet with sharp edges, or (ii) a jet with a narrow core and...
Afterglow Observations Shed New Light on the Nature of X-ray Flashes (2005)
Granot, Jonathan, Ramirez-Ruiz, Enrico, Perna, Rosalba
X-ray flashes (XRFs) and X-ray rich gamma-ray bursts (XRGRBs) share many observational characteristics with long duration GRBs, but the reason for which their prompt emission peaks at lower photon...
Radio Flares and the Magnetic Field Structure in GRB Outflows (2004)
Granot, Jonathan, Taylor, Gregory B.
The magnetic field structure in GRB outflows is of great interest as it can provide valuable clues that can help pin down the mechanism responsible for the acceleration and collimation of GRB jets....
An Off-Axis Model for GRB 031203 (2004)
Ramirez-Ruiz, Enrico, Granot, Jonathan, Kouveliotou, Chryssa, Woosley, S. E., Patel, Sandy K., Mazzali, Paolo A.
The low luminosity radio emission of the unusually faint GRB 031203 has been argued to support the idea of a class of intrinsically sub-energetic gamma-ray bursts (GRBs), currently comprising two...
Two-Component Jet Models of Gamma-Ray Burst Sources (2004)
Peng, Fang, Konigl, Arieh, Granot, Jonathan
Recent observational and theoretical studies have raised the possibility that the collimated outflows in gamma-ray burst (GRB) sources have two distinct components: a narrow (opening half-angle...
Implications of the Measured Image Size for the Radio Afterglow of GRB 030329 (2004)
Granot, Jonathan, Ramirez-Ruiz, Enrico, Loeb, Abraham
We use data on the image size of the radio afterglow of GRB 030329 (Taylor et al. 2004) to constrain the physical parameters of this explosion. Together with the observed broad band spectrum, this...
Constraining the Structure of GRB Jets Through the log(N)-log(S) Distribution (2004)
Guetta, Dafne, Granot, Jonathan, Begelman, Mitchell C.
A general formalism is developed for calculating the luminosity function and the expected number $N$ of observed GRBs above a peak photon flux $S$ for any GRB jet structure. This new formalism...
The Case for a Misaligned Relativistic Jet from SN 2001em (2004)
Granot, Jonathan, Ramirez-Ruiz, Enrico
SN 2001em, identified as a Type Ic supernova, has recently been detected in the radio and X-rays, $\gtrsim$ 2 yr after the explosion. The high luminosities at such late times might arise from a...
High Energy Emission from the Double Pulsar system J0737-3039 (2004)
Granot, Jonathan, Meszaros, Peter
We discuss the effects of particle acceleration at the bow shocks expected in the binary pulsar system J0737-3039, due to the wind from pulsar A interacting with both the interstellar medium (ISM),...
Ehud Nakar, Jonathan Granot, Dafne Guetta
The two leading models for the structure of gamma-ray burst (GRB) jets are the uniform jet model and the universal structured jet (USJ) model. In the latter, all GRB jets are intrinsically identical...
Some Recent Peculiarities of the Early Afterglow (2003)
Piran, Tsvi, Nakar, Ehud, Granot, Jonathan
We consider some recent developments in GRB/afterglow observations: (i) the appearance of a very hard prompt component in GRB 941017, and (ii) variability in the early afterglow light curves of GRB...
Testing the Predictions of the Universal Structured GRB Jet Model (2003)
Nakar, Ehud, Granot, Jonathan, Guetta, Dafne
The two leading models for the structure of GRB jets are the uniform jet model and the universal structured jet (USJ) model. In the latter, all GRB jets are intrinsically identical and the energy per...
Explaining the High Energy Spectral Component in GRB 941017 (2003)
Granot, Jonathan, Guetta, Dafne
The gamma-ray burst (GRB) of October 17, 1994 (941017), showed a distinct high energy spectral component extending from $\lesssim$ a few MeV to $\gtrsim$ 200 MeV, in addition to the typical GRB...
The Most Probable Cause for the High Gamma-Ray Polarization in GRB 021206 (2003)
The exciting detection of a very high degree of linear polarization, $P=(80\pm 20)%$, in the prompt gamma-ray emission of GRB 021206, supports synchrotron emission as being the dominant radiation...
Radio Imaging of GRB Jets in Nearby Supernovae (2003)
Granot, Jonathan, Loeb, Abraham
We calculate the time evolution of the flux, apparent size, and image centroid motion of gamma-ray burst (GRB) radio jets, and show that they can be resolved by the VLBA at distances of hundreds of...
The Variable Light Curve of GRB 030329: The Case for Refreshed Shocks (2003)
Granot, Jonathan, Nakar, Ehud, Piran, Tsvi
GRB 030329 is unique in many aspects. It has a very low redshift for a GRB, $z=0.1685$, and is therefore very bright and easy to monitor, making it the most well studied afterglow to date. It shows a...
Linear Polarization in Gamma-Ray Bursts: The Case for an Ordered Magnetic Field (2003)
Granot, Jonathan, Konigl, Arieh
Linear polarization at the level of $\sim 1-3%$ has by now been measured in several gamma-ray burst afterglows. Whereas the degree of polarization, $P$, was found to vary in some sources, the...
The Evolution of a Structured Relativistic Jet and GRB Afterglow Light-Curves (2003)
Kumar, Pawan, Granot, Jonathan
We carry out a numerical hydrodynamical modeling for the evolution of a relativistic collimated outflow, as it interacts with the surrounding medium, and calculate the light-curve resulting from...
Gamma Ray Bursts in Pulsar Wind Bubbles: Observational implications (2003)
Guetta, Dafne, Granot, Jonathan
We present the main observational features expected for Gamma-Ray Bursts (GRBs) that occur inside pulsar wind bubbles (PWBs). This is the most natural outcome of the supranova model, where initially...
The Jet Angular Profile and the Afterglow Light Curves (2003)
Granot, Jonathan, Kumar, Pawan, Piran, Tsvi
We investigate how the angular structure of GRB jets effects the afterglow light curves at different viewing angles, $\theta_{v}$, from the jet symmetry axis. A numerical hydrodynamical modeling for...
Constraining the Structure of GRB Jets Through the Afterglow Light Curves (2002)
Granot, Jonathan, Kumar, Pawan
We investigate the effect that the structure of GRB jets has on the afterglow light curves for observers located at different viewing angles, $\theta_{obs}$, from the jet symmetry axis. The largest...
Neutrinos from Gamma-Ray Bursts in Pulsar Wind Bubbles: \sim 10^{16} eV (2002)
Guetta, Dafne, Granot, Jonathan
The supranova model for Gamma-Ray Bursts (GRBs) is becoming increasingly more popular. In this scenario the GRB occurs weeks to years after a supernova explosion, and is located inside a pulsar wind...
Neutrinos from Pulsar Wind Bubbles as Precursors to Gamma-Ray Bursts (2002)
Granot, Jonathan, Guetta, Dafne
The supranova model for gamma-ray bursts (GRBs) has recently gained popularity. In this scenario the GRB occurs weeks to years after a supernova explosion, and is located inside a pulsar wind bubble...
Gamma-Ray Bursts in Pulsar Wind Bubbles: Putting the Pieces Together (2002)
Granot, Jonathan, Guetta, Dafne
We present the main observational features expected for GRBs that occur inside pulsar wind bubbles (PWBs). This is the most natural outcome of supranova model where initially a supernova explosion...
Variability in GRB Afterglows and GRB 021004 (2002)
Nakar, Ehud, Piran, Tsvi, Granot, Jonathan
We present general analytic expressions for GRB afterglow light curves arising from a variable external density profile and/or a variable energy in the blast wave. The former could arise from a...
High Energy Emission from the Prompt Gamma-Ray Burst (2002)
Guetta, Dafne, Granot, Jonathan
We study the synchrotron and synchrotron self-Compton (SSC) emission from internal shocks that are responsible for the prompt gamma-ray emission in GRBs, and consider the relation between these two...
The Mean Number of Extra Micro-Image Pairs for Macro-Lensed Quasars (2002)
Granot, Jonathan, Schechter, Paul L., Wambsganss, Joachim
When a gravitationally lensed source crosses a caustic, a pair of images is created or destroyed. We calculate the mean number of such pairs of micro-images $$ for a given macro-image of a...
Observational Implications of a Plerionic Environment for GRBs (2002)
Guetta, Dafne, Granot, Jonathan
We consider GRBs that occur inside pulsar wind bubbles (PWBs), in the context of the supranova model, where initially a supernova explosion takes place, leaving behind a supra-massive neutron star...
The Detectability of Orphan Afterglows (2002)
Nakar, Ehud, Piran, Tsvi, Granot, Jonathan
The realization that GRBs release a constant amount of energy implies that the post jet-break afterglow evolution would be largely universal. For a given redshift all afterglows should be detected up...
Gamma-Ray Burst Afterglows in Pulsar-Wind Bubbles (2001)
Konigl, Arieh, Granot, Jonathan
We propose to identify pulsar-wind bubbles (PWBs) as the environment in which the afterglow emission in at least some gamma-ray bursts (GRBs) originates. Such bubbles could naturally account for the...
The Shape of Spectral Breaks in GRB Afterglows (2001)
Gamma-Ray Burst (GRB) afterglows are well described by synchrotron emission from relativistic blast waves expanding into an external medium. The blast wave is believed to amplify the magnetic field...
Theory of GRB Afterglow (2001)
The most interesting current open question in the theory of GRB afterglow is the propagation of jetted afterglows during the sideway expansion phase. Recent numerical simulations show hydrodynamic...
Microlensing and the Surface Brightness Profile of the Afterglow Image of GRB 000301C (2001)
Gaudi, B. Scott, Granot, Jonathan, Loeb, Abraham
The optical afterglow of Gamma-Ray Burst (GRB) 000301C exhibited a significant, short-timescale deviation from the power-law flux decline expected in the standard synchrotron shock model. Garnavich,...
Radiative Hydromagnetic Shocks in Relativistic Outflow Sources (2001)
Granot, Jonathan, Konigl, Arieh
We calculate the structure of a relativistic shock wave in which the internal energy of the shocked fluid is radiated away on a time scale much shorter than the characteristic shock propagation time....
Light Curves from an Expanding Relativistic Jet (2001)
Granot, Jonathan, Miller, Mark, Piran, Tsvi, Suen, Wai-Mo, Hughes, Philip A.
We perform fully relativistic hydrodynamic simulations of the deceleration and lateral expansion of a relativistic jet as it expands into an ambient medium. The hydrodynamic calculations use a 2D...
Chromatic Signatures in the Microlensing of GRB Afterglows (2001)
Granot, Jonathan, Loeb, Abraham
We calculate the radial surface brightness profile of the image of a Gamma-Ray-Burst (GRB) afterglow. The afterglow spectrum consists of several power-law segments separated by breaks. The image...
The synchrotron spectrum of fast cooling electrons revisited (2000)
Granot, Jonathan, Piran, Tsvi, Sari, Re'em
We discuss the spectrum arising from synchrotron emission by fast cooling electrons when fresh electrons are continually accelerated by a strong blast wave into a power law distribution of energies....
The Synchrotron Spectrum of Fast Cooling Electrons Revisited (2000)
Granot, Jonathan, Piran, Tsvi, Sari, Re'em
We discuss the spectrum arising from synchrotron emission by fast cooling (FC) electrons, when fresh electrons are continually accelerated by a strong blast wave, into a power law distribution of...
Granot, Jonathan, Miller, Mark, Piran, Tsvi, Suen, Wai-Mo
We describe fully relativistic three dimensional calculations of the slowing down and spreading of a relativistic jet by an external medium like the ISM. We calculate the synchrotron spectra and...
Images, Light Curves and Spectra of GRB Afterglow (1999)
Granot, Jonathan, Piran, Tsvi, Sari, Re'em
We calculate the light curve and spectra near the peak and the self absorption break, for an adiabatic blast wave described by the Blandford-McKee solution, considering the emission from the whole...
Synchrotron Self Absorption in GRB Afterglow (1998)
Granot, Jonathan, Piran, Tsvi, Sari, Re'em
GRB afterglow is reasonably described by synchrotron emission from relativistic blast waves at cosmological distances. We perform detailed calculations taking into account the effect of synchrotron...
Images and Spectra From the Interior of a Relativistic Fireball (1998)
Granot, Jonathan, Piran, Tsvi, Sari, Re'em
The detection of an afterglow, following a gamma-ray burst (GRB), can be described reasonably well by synchrotron emission from a relativistic spherical expanding blast wave, driven by an expanding...