Open AccessNuclear spirals in galaxies: gas response to an asymmetric potential – II. Hydrodynamical models
Author(s) -
Maciejewski Witold
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08254.x
Subject(s) - physics , astrophysics , asymmetry , accretion (finance) , galaxy , spiral galaxy , active galactic nucleus , inflow , spiral (railway) , black hole (networking) , astronomy , mechanics , quantum mechanics , mathematical analysis , computer network , routing protocol , routing (electronic design automation) , mathematics , computer science , link state routing protocol
Nuclear spirals naturally form as a gas response to non‐axisymmetry in the galactic potential, even if the degree of this asymmetry is very small. Linear wave theory well describes weak nuclear spirals, but spirals induced by stronger asymmetries in the potential are clearly beyond the linear regime. Hydrodynamical models indicate spiral shocks in this latter case that, depending on how the spiral intersects the x 2 orbits, either get damped, leading to the formation of the nuclear ring, or get strengthened, and propagate towards the galaxy centre. A central massive black hole of sufficient mass can allow the spiral shocks to extend all the way to its immediate vicinity, and to generate gas inflow up to 0.03 M ⊙ yr −1 , which coincides with the accretion rates needed to power luminous local active galactic nuclei.