2003/07/02 by E. M. de Gouveia Dal Pino, A. Lazarian, Pino, E. M. de Gouveia Dal +1 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Pulsars and Gravitational Waves Research #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0307054
A&A, in press; 3 figures; revised version has suffered few important modifications
openalex publication_date 2003/07/02 · arxiv created 2005/06/21 · openalex created_date 2016/06/24 · arxiv updated 2016/08/30 · openalex updated_date 2026/07/28
We here propose that the large scale superluminal ejections observed in the galactic microquasar GRS 1915+105 during radio flare events are produced by violent magnetic reconnection episodes in the corona just above the inner edge of the magnetized accretion disk that surrounds the central ∼ 10 M\odot black hole. The process occurs when a large scale magnetic field is established by turbulent dynamo in the inner disk region with a ratio between the gas+radiation and the magnetic pressures β≃ 1, implying a magnetic field intensity of ∼ 7 × 108 G. During this process, substantial angular momentum is removed from the disk by the wind generated by the vertical magnetic flux therefore increasing the disk mass accretion to a value near (but below) the critical one ( M ∼ 1019 g s-1). Part of the magnetic energy released by reconnection heats the coronal gas (Tc \lesssim 5 × 108 K) that produces a steep, soft X-ray spectrum with luminosity LX ≃ 1039 erg s- 1, in consistency with observations. The remaining magnetic energy released goes to accelerate the particles to relativistic velocities (v ∼ vA ∼ c, where vA is the Alfvén speed) in the reconnection site through first-order Fermi processes. In this context, two possible mechanisms have been examined which produce power-law electron distributions N(E) ∝ E-αE, with αE = 5/2, 2, and corresponding synchrotron radio power-law spectra with spectral indices which are compatible with that observed during the flares ( Sν ∝ ν-0.75, - 0.5).