1999/12/15 by Rafael Angel Araya-Gochez, Rafael A. Araya-Góchez, Araya-Gochez, Rafael Angel
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9912324
14 pgs, no figures, submitted to M.N.R.A.S. V2: slightly revised text, citations and output numbers
openalex publication_date 1999/12/15 · arxiv created 2000/01/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Recent evidence of the phenomenal energetics involved in gamma ray burst events strongly suggests that the progenitor must efficiently convert gravitational binding energy into a moderately collimated outflow, possibly in the form of a Poynting jet. We show that an MHD-instability driven dynamo (IDD) operating in a hot accretion disk is capable of generating energetically adecuate magnetic flux deposition rates above and below a mildly advective accretion disk structure. The dynamo is driven by the magnetorotational instability (MRI) of a toroidal field in a shear flow and is limited by the buoyancy of `horizontal' flux and by reconnection in the turbulent medium. In the comoving frame of a semi-thick, slim disk setting, the predominant field components reside in surfaces perpendicular to the local meridian and the flux is deposited in funnels that are relatively free of baryons. The efficiency of magnetic energy deposition is estimated to be comparable to the neutrino losses but the strong effective shear induced by the metric on the MRI favors pumping magnetic field energy at low wavenumbers, i.e., field generation at large coherence lengthscales. This, in turn, suggests that an MHD collimation mechanism may deem this process a more viable alternative to neutrino-burst--driven models of gamma ray bursts.