2015/01/31 by Mahmood Roshan, Shahram Abbassi · 25 citations
Mathematics · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Cosmology and Gravitation Theories #Function (biology) #Galaxy #Instability #Mathematical analysis #Mathematical physics #Mathematics #Mechanics #Physics #Sigma #Spiral (railway) #Spiral galaxy #Stability (learning theory) #Stability criterion #Statistics #Stellar, planetary, and galactic studies #Velocity dispersion #astro-ph.GA #gr-qc
paper · pdf · doi:10.1088/0004-637x/802/1/9
published in The Astrophysical Journal 802(1), 9 (IOP Publishing) · 9 pages, 5 figures, 1 table
openalex publication_date 2015/03/13 · arxiv created 2015/03/14 · arxiv updated 2015/03/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We find the dispersion relation for tightly wound spiral density waves in the surface of rotating, self-gravitating disks in the framework of Modified Gravity (MOG). Also, the Toomre-like stability criterion for differentially rotating disks has been derived for both fluid and stellar disks. More specifically, the stability criterion can be expressed in terms of a matter density threshold over which the instability occurs. In other words the local stability criterion can be written as , where is a function of v s (sound speed), κ (epicycle frequency) and α and are the free parameters of the theory. In the case of a stellar disk the radial velocity dispersion appears in instead of v s . We find the exact form of the function for both stellar and fluid self-gravitating disks. Also, we use a sub-sample of THINGS catalog of spiral galaxies in order to compare the local stability criteria. In this perspective, we have compared MOG with Newtonian gravity and investigated the possible and detectable differences between these theories.