Stability of galaxies across morphological sequence

K. Aditya

doi:10.1093/mnras/stad1143

paper

Stability of galaxies across morphological sequence

arXiv:2304.07734 · doi:10.1093/mnras/stad1143

Abstract

We investigate the stability of nearby disc galaxies and galaxies at redshift ( $z$ ) equal to 4.5. We explore the connection between the stability parameter $(Q_{R W})$ , star formation rate ( $S F R$ ), gas fraction $(f^{G a s})$ , and the time scale for growth of gravitational instabilities $(τ)$ . We find that, despite differences in morphology $91$ $%$ of the nearby galaxies have a minimum value of stability parameter ( $Q_{R W}^{M in}$ ) greater than $1$ indicating stability against the growth of axisymmetric instabilities. The spirals in our sample have higher median star formation rate, lower median $Q_{R W}$ , a lower $f^{G a s}$ and small time scale for growth of gravitational instabilities than irregular galaxies. We find that the gravitational instabilities in spirals convert a large fraction of gas into stars quickly, depleting the gas reservoirs. On the other hand, star formation occurs more gradually over longer timescales in irregulars with a higher gas fraction. We then compare the stability of the nearby galaxies with galaxies at $z = 4.5$ . We find that net stability levels in the nearby galaxies and the galaxies at $z = 4.5$ are primarily driven by the stellar disc suggesting the presence of an inherent mechanism that self-regulates the stability. Finally, upon removing the contribution of the dark matter to the total potential, the median $Q_{R W}$ for the nearby galaxies and galaxies at $z = 4.5$ remains unchanged indicating that the baryons can self-regulate the stability levels, at least in a statistical sense.

arXiv commentAccepted for publication in MNRAS

Stability of galaxies across morphological sequence

Abstract

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