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.

arXiv comment9 pages, 5 figures, 1 table

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• Jeans analysis in energy-momentum-squared gravity
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• Large Distance Modification of Newtonian Potential and Structure Formation in Universe
• Clustering of Galaxies in Brane World Models
• Post-Newtonian Jeans analysis
• The phase space analysis of modified gravity (MOG)
• Global stability of self-gravitating disks in modified gravity
• Local fragmentation of thin disks in Eddington-inspired gravity
• Evolution of spiral galaxies in nonlocal gravity
• Angular momentum of disc galaxies with a lognormal density distribution
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• Stellar Bar evolution in the absence of dark matter halo
• Local stability of self-gravitating disks in $f(R)$ gravity
• Wave Propagation in Modified Gravity
• On the gravitational stability of the Maclaurin disk
• Low-mass disc galaxies and the issue of stability: MOND vs dark matter
• Local Stability of Galactic Discs in Modified Dynamics
• The Jeans theorem and the "Tolman-Oppenheimer-Volkov equation" in an exact wave solution of R^2 gravity
• Stability of Differentially Rotating Disks in $f(T)$ Theory
• The Weak Lensing Mass of Cosmic Web Filaments and Modified Gravity (MOG)