Compton-dragged Gamma-Ray Bursts Associated with Supernovae

Abstract

It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e., the overall energetics, the peak frequency of the spectrum, and the fast variability, with an efficiency that can exceed 50%. In this scenario, there is no need for particle acceleration in relativistic collisionless shocks. Furthermore, although the Poynting flux may be important in accelerating the outflow, no magnetic field is required in the gamma-ray production. The drag also naturally limits the relativistic expansion of the fireball to . 4G Շ 10

On the Generation of Ultra–High‐Energy Cosmic Rays in Gamma‐Ray Bursts: A Reappraisal

“…We remark that these derived efficiencies always exceed the largest efficiency achievable in converting rest mass into photons around maximally rotating black holes (43%). Although this is not a strict theoretical upper limit (models approaching 100% have been proposed; Lazzati et al 2000), still values derived from observations are so large as to throw doubts on the validity of the present version of internal-shock model. In fact, the maximum efficiency that can be reached with this model is of the order of 20% (Guetta, Spada, & Waxman 2001a), but only under ad hoc assumptions: for random distributions in the wind properties, the efficiency cannot exceed %0.005 (Spada et al 2000).…”

“…In fact, the maximum efficiency that can be reached with this model is of the order of 20% (Guetta, Spada, & Waxman 2001a), but only under ad hoc assumptions: for random distributions in the wind properties, the efficiency cannot exceed %0.005 (Spada et al 2000). Perfectly efficient models without internal shocks can be conceived (Lazzati et al 2000), but they cannot account for bursts' spectra (Ghisellini et al 2000b).…”

Open questions in GRB physics

“…These photon sources include the thermal photons released from the exploding star [244], the thermal photon "glory" from the progenitor star that is trapped by the environment [245], as well as thermal photons from shock breakout [246].…”

Detection of Low-energy Breaks in Gamma-Ray Burst Prompt Emission Spectra

“…The proposed solutions can be classified into two types: models that invoke emission mechanisms different than synchrotron radiation, and models that propose modifications to the basic synchrotron scenario. Among the first class of models, we recall scenarios invoking Comptonization and/or thermal components Blinnikov et al 1999;Ghisellini & Celotti 1999;Lazzati et al 2000;Mészáros & Rees 2000;Stern & Poutanen 2004;Rees & Mészáros 2005;Ryde & Pe'er 2009;Guiriec et al 2011Guiriec et al , 2015aGuiriec et al ,b, 2016aGhirlanda et al 2013;Burgess et al 2014). For the second class of models (studies that consider synchrotron radiation) effects producing a hardening of the low-energy spectral index have been invoked, such as Klein-Nishina effects, marginally fast cooling regime, and anisotropic pitch angle distributions (Lloyd & Petrosian 2000;Derishev 2001Derishev , 2007Bosnjak et al 2009;Nakar et al 2009;Daigne et al 2011;Uhm & Zhang 2014).…”