On the stability of a galactic disk in modified gravity

Abstract

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 ${\Sigma }_0<{\Sigma }_{\text{crit}}(v_s,\kappa ,\alpha ,{\mu }_0)$, where ${\Sigma }_{\text{crit}}$ is a function of $v_s$ (sound speed), $\kappa$ (epicycle frequency) and $\alpha$ and ${\mu }_0$ are the free parameters of the theory. In the case of a stellar disk the radial velocity dispersion ${\sigma }_r$ appears in ${\Sigma }_{\text{crit}}$ instead of $v_s$. We find the exact form of the function ${\Sigma }_{\text{crit}}$ 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.

9 pages, 5 figures, 1 table

References in corpus (8)

• The Bullet Cluster 1E0657-558 evidence shows Modified Gravity in the absence of Dark Matter
• Evolution of spiral galaxies in modified gravity
• Testing modified gravity with globular cluster velocity dispersions
• Fundamental parameter-free solutions in Modified Gravity
• Jeans analysis in modified gravity
• Synthetic Spectra of Radio, Millimeter, Sub-millimeter and Infrared Regimes with NLTE approximation
• Probing Brownstein-Moffat Gravity via Numerical Simulations
• Local stability criterion for self-gravitating disks in modified gravity

Cited by in corpus (9)

• Dark matters on the scale of galaxies
• Jeans analysis in energy-momentum-squared gravity
• Barred spiral galaxies in modified gravity theories
• The phase space analysis of modified gravity (MOG)
• Evolution of spiral galaxies in nonlocal gravity
• Local stability of self-gravitating disks in $f(R)$ gravity
• On the gravitational stability of the Maclaurin disk
• Local Stability of Galactic Discs in Modified Dynamics
• Low-mass disc galaxies and the issue of stability: MOND vs dark matter