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Clues from the prompt emission of GRB 080319B
Y. C. Zou, T. Piran, R. Sari
The extremely bright optical flash that accompanied GRB 080319B suggested, at first glance, that the prompt -rays in this burst were produced by Synchrotron self Compton (SSC).…
Levy Flights of Binary Orbits due to Impulsive Encounters
Benjamin F. Collins, Re'em Sari
We examine the evolution of an almost circular Keplerian orbit interacting with unbound perturbers. We calculate the change in eccentricity and angular momentum that results from a…
GeV Emission from Prompt and Afterglow Phases of Gamma-Ray Bursts
Shin'ichiro Ando, Ehud Nakar, Re'em Sari
We investigate the GeV emission from gamma-ray bursts (GRBs), using the results from the Energetic Gamma Ray Experimental Telescope (EGRET), and in view of the Gamma-ray Large Area…
Observational Limits on Inverse Compton Processes in GRBs
Tsvi Piran, Re'em Sari, Yuan-Chuan Zou
Inverse Compton (IC) scattering is one of two viable mechanisms that can produce the prompt gamma-ray emission in Gamma-Ray Bursts. IC requires low energy seed photons and a popula…
The Ratio of Retrograde to Prograde Orbits: A Test for Kuiper Belt Binary Formation Theories
Hilke E. Schlichting, Re'em Sari
With the discovery of Kuiper Belt binaries that have wide separations and roughly equal masses new theories were proposed to explain their formation. Two formation scenarios were s…
Composite self-similar solutions for relativistic shocks: the transition to cold fluid temperatures
Margaret Pan, Re'em Sari
The flow resulting from a strong ultrarelativistic shock moving through a stellar envelope with a polytrope-like density profile has been studied analytically and numerically at ea…
Tidal Evolution of Rubble Piles
Peter Goldreich, Re'em Sari
Many small bodies in the solar system are believed to be rubble piles, a collection of smaller elements separated by voids. We propose a model for the structure of a self-gravitati…
Formation of Kuiper Belt Binaries
Hilke E. Schlichting, Re'em Sari
The discovery that a substantial fraction of Kuiper Belt objects (KBOs) exists in binaries with wide separations and roughly equal masses, has motivated a variety of new theories e…
Co-orbital Oligarchy
Benjamin F. Collins, Re'em Sari
We present a systematic examination of the changes in semi-major axis caused by the mutual interactions of a group of massive bodies orbiting a central star in the presence of ecce…
The effect of Semi-Collisional Accretion on Planetary Spins
Hilke E. Schlichting, Re'em Sari
Planetesimal accretion during planet formation is usually treated as collisionless. Such accretion from a uniform and dynamically cold disk predicts protoplanets with slow retrogra…
The Self-Similarity of Shear-Dominated Viscous Stirring
Benjamin F. Collins, Hilke E. Schlichting, Re'em Sari
We examine the growth of eccentricities of a population of particles with initially circular orbits around a central massive body. Successive encounters between pairs of particles…
Protoplanet Dynamics in a Shear-Dominated Disk
Benjamin F. Collins, Re'em Sari
The velocity dispersion, or eccentricity distribution, of protoplanets interacting with planetesimals is set by a balance between dynamical friction and viscous stirring. We calcul…
Spherical Accretion
Re'em Sari, Peter Goldreich
We compare different examples of spherical accretion onto a gravitating mass. Limiting cases include the accretion of a collisionally dominated fluid and the accretion of collision…
Self-similar solutions for relativistic shocks emerging from stars with polytropic envelopes
Margaret Pan, Re'em Sari
We consider a strong ultrarelativistic shock moving through a star whose envelope has a polytrope-like density profile. When the shock is close to the star's outer boundary, its be…
First and second-type self-similar solutions of implosions and explosions containing ultra-relativistic shocks
Re'em Sari
We derive self similar solutions for ultra-relativistic shock waves propagating into cold material of powerlaw density profile in radius rho ~ r^-k. We treat both implosions and ex…
Pure and loaded fireballs in SGR giant flares
Ehud Nakar, Tsvi Piran, Re'em Sari
On December 27, 2004, a giant flare from SGR 180620 was detected on earth. Its thermal spectrum and temperature suggest that the flare resulted from an energy release of about $…
Planet Formation by Coagulation: A Focus on Uranus and Neptune
Peter Goldreich, Yoram Lithwick, Re'em Sari
Planets form in the circumstellar disks of young stars. We review the basic physical processes by which solid bodies accrete each other and alter each others' random velocities, an…
Final Stages of Planet Formation
Peter Goldreich, Yoram Lithwick, Re'em Sari
We address three questions regarding solar system planets. What determined their number? Why are their orbits nearly circular and coplanar? How long did they take to form? Runaway…
Shaping the Kuiper belt size spectrum by shattering large but strengthless bodies
Margaret Pan, Re'em Sari
The observed size distribution of Kuiper belt objects (KBOs)--small icy and rocky solar system bodies orbiting beyond Neptune--is well described by a power law at large KBO sizes.…
Evolution of the polarization of the optical afterglow of the gamma-ray burst GRB 030329
J. Greiner, S. Klose, K. Reinsch +23
We report 31 polarimetric observations of the afterglow of GRB 030329 with high signal-to-noise and high sampling frequency. We establish the polarization light curve, detect susta…
Planet - Disk Symbiosis
Re'em Sari, Peter Goldreich
Planets form in disks around young stars. Interactions with these disks cause them to migrate and thus affect their final orbital periods. We suggest that the connection between pl…
Jets in GRBs: Tests and Predictions for the Structured Jet Model
Rosalba Perna, Re'em Sari, Dale Frail
The two leading interpretations of achromatic breaks that are observed in the light curves of GRBs afterglow are (i) the manifestation of the edge of a jet, which has a roughly uni…
A generalization of the Lagrangian points: studies of resonance for highly eccentric orbits
Margaret Pan, Re'em Sari
We develop a framework based on energy kicks for the evolution of high-eccentricity long-period orbits with Jacobi constant close to 3 in the restricted circular planar three-body…
Cosmological Uses of Gamma-Ray Bursts
S. G. Djorgovski, S. R. Kulkarni, D. A. Frail +12
Studies of the cosmic gamma-ray bursts (GRBs) and their host galaxies are starting to provide interesting or even unique new insights in observational cosmology. GRBs represent a n…