The local axisymmetric instability criterion in a thin, rotating, multicomponent disc

By R. Rafikov. 2000

146 citations recorded by the source corpus.

Purely gravitational perturbations are considered in a thin rotating disc composed of gas and several stellar components. The dispersion relation for the axisymmetric density waves propagating through the disc is found and the criterion for the local axisymmetric stability of the whole system is formulated. In the appropriate limit of two-component gas we confirm the findings of Jog & Solomon and extend consideration to the case when one component is collisionless. Gravitational stability of the Galactic disc in the solar neighbourhood based on the multicomponent instability condition is explored using recent measurements of the stellar composition and kinematics in the local Galactic disc obtained by the Hipparcos satellite.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/6e002c3db84ddfda0018a128e5ac9f4b771b865e

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In Astronomy and Astrophysics

Citations in the corpus

Feedback-regulated star formation in molecular clouds and galactic discs (2013, result): “When the gas turbulent velocity dispersion is much smaller than the stellar velocity dispersion, the results of Rafikov (2001) imply that the effective Q criterion for the gas only in equation (6) is a good approximation to the stability of the disc.”
THE STAR FORMATION EFFICIENCY IN NEARBY GALAXIES: MEASURING WHERE GAS FORMS STARS EFFECTIVELY (2008, unknown): “Rafikov (2001) extended work by Jog & Solomon (1984) to provide a straightforward way to calculate the instability of a gas disk in the presence of a collisionless stellar disk.”
Dawes Review 4: Spiral Structures in Disc Galaxies (2014, background): “Rafikov (2001) derived the dispersion relation for a disc with a fluid, and a collisionless component (see also Romeo 1992): 2πGk g0 κ2 + k2c2g − ω2 + 2πGk s0F κ2 − ω2 = 1 (33) where F is defined as for Equation 9.”
Physical Processes in the Interstellar Medium (2014, background): “In the case of a disk that contains a mix of gas and stars, the analysis is more complex (see e.g. Rafikov, 2001; Elmegreen, 2011), but the required value of Q remains close to unity.”
High-redshift clumpy discs and bulges in cosmological simulations (2009, background): “The first term has to be slightly modified to take into account the dissipationless nature of the stars but this correction makes only a small difference (Rafikov 2001).”
A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, background): “…gravitational instability include the effects of multiple stellar populations as well as gas, along with the effects of finite thickness and the dissipative nature of gas (Rafikov 2001; Romeo, Burkert & Agertz 2010; Elmegreen 2011; Romeo & Wiegert 2011; Hoffmann & Romeo 2012; Romeo & Falstad 2013).”
The lifetimes of spiral patterns in disc galaxies (2010, background): “It should also be noted that the raw Q-value estimated from the stars only may not be the relevant quantity in realistic discs, where the gas component and perhaps also the young stellar population can have a disproportionate effect on the overall responsiveness (Rafikov 2001).”
EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES (2010, background): “Equation 4 assumes the mass budget to be dominated by gas (ignoring the stellar contribution considered by, e.g., Jog & Solomon 1984; Rafikov 2001; Yang et al. 2007); we consider this a reasonable approximation outside r25.”
A General Theory of Turbulence-regulated Star Formation, from Spirals to Ultraluminous Infrared Galaxies (2005, background): “This occurs because the gas comprises a small fraction of the total surface density of the disk and because old stars have had a long time to scatter off molecular clouds (Rafikov 2001).”
The Secular Evolution of Disk Structural Parameters (2005, methodology): “…disks have Q 2 over most of the radial extent of the galaxy, which should make the system unstable to non-axisymmetric perturbations irrespective of the stellar Q (see Rafikov 2001 for the case in which the sound speed cs is ∼ 0.3 of the radial stellar velocity dispersion as in our models).”
Molecular Hydrogen and Global Star Formation Relations in Galaxies (2007, unknown): “…criterion for axisymmetric modes with a wavenumberk can be expressed in terms of the normalized wavenumberq ≡ kc⋆/κ and the ratio of velocity dispersionsR ≡ σ/c⋆ as Q−1sg ≡ 2 Qs q 1+ q2 + 2 Qg R q 1+ q2R2 > 1 (29) (Jog & Solomon 1984; Rafikov 2001), whereQs = ΣQ(c⋆)/Σ⋆ andQg = ΣQ(σ)/Σgas.”
Global Models for the Evolution of Embedded, Accreting Protostellar Disks (2007, methodology): “For simplicity, we assume that while fragments contribute to the mass of the disk, they do not enter in Toomre’s stability parameter Q except insofar as they contribute to the binding mass. (One could consider a composite Q: Rafikov 2001.)”
EVOLVING GRAVITATIONALLY UNSTABLE DISKS OVER COSMIC TIME: IMPLICATIONS FOR THICK DISK FORMATION (2011, methodology): “We adopt a modified version of the condition determined by Rafikov (2001), wherein the stability of a multi-component disk is considered with the stars treated realistically as a collisionless fluid.”
FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS (2009, background): “The axisymmetric instability of a twocomponent disk has been studied by Jog & Solomon (1984) and Rafikov (2001).”