2004/01/26 by M. Tagger, Michel Tagger, Peggy Varniere +5 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #astro-ph
paper · pdf · doi:10.1086/383232
published as Astrophys.J. 607 (2004) 410-419 · 11 pages, 5 color figures (3 color, quality lowered), accepted for publication in ApJ. Full quality paper (ps) available at http://isdc.unige.ch/~rodrigue/FTP/Flood_Tagger.ps
arxiv created 2004/01/26 · openalex publication_date 2004/05/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present a scenario for the variability of the microquasar GRS 1915+105. This starts from previous works, leading to the tentative identification of the accretion-ejection instability as the source of the low-frequency quasi-periodic oscillation of microquasars and other accreting sources. We follow the physics of this instability: its conditions (the magnetic field and geometry adapted to MHD jet models), its instability criterion, and its consequences (cooling down of the disk, heating and excitation of the corona). Comparing them to the observed properties of the source, in particular the detailed properties of its spectral states, we first derive a model of the ~30 minute cycles often exhibited by GRS 1915+105. In our model this is a limit cycle determined by the advection of poloidal magnetic flux to the inner region of the disk and its destruction by reconnection (leading to relativistic ejections) with the magnetic flux trapped in the vicinity of the central source. We show how this leads to natural explanations of observed behaviors of GRS 1915+105, including the three basic states of Belloni and coworkers. We then discuss how this could be extrapolated further to understand the longer term variability of this microquasar and others.