A study conducted by the Indian Institute of Astrophysics (IIA) could help understand how gravitational instabilities are connected to galaxy evolution.
K. Aditya, a post-doctoral fellow at the IIA, tried to explore how gravitational instabilities are connected with the star formation, gas fraction, time scale for growth of gravitational instabilities and finally, the observed morphology.
“They then compared the star formation rate, gas fraction, and time scale for the growth of gravitational instabilities of nearby galaxies and investigated the stability levels of a sample of 175 galaxies taken from the Spitzer Photometry and Accurate Rotation Curves (SPARC) database. This helped them trace the role of dark matter in regulating the stability levels of the galaxies and understand if stars and gas can self-regulate the stability levels,” Department of Science and Technology (DST) said.
The ways of Milky Way
DST added that they found that spiral galaxies like the Milky Way exhibit a higher median star formation rate, lower stability, lower gas fraction, and a smaller time scale for the growth of gravitational instabilities.
“This indicates that gravitational instabilities in spirals rapidly convert a substantial amount of gas into stars, depleting the gas reservoirs,” DST added.
It further said that the study which compared the stability levels in the nearby galaxies with those observed at high redshift, which are precursors to the galaxies in the local universe, could help understand how gravitational instabilities are connected to galaxy evolution.
Pace of star formation
The results obtained in this work suggest a simple mechanism in which galaxies characterized by marginal stability levels undergo intense star formation activity for a short time scale, depleting the gas reserves. Whereas in galaxies that are highly stable, the star formation proceeds more slowly over longer time scales in galaxies with relatively higher stability gradually converting the available gas into stars.
The study not only contributes to the understanding of gravitational instabilities but also emphasizes the need for future investigations into the impact of these instabilities on the morphological evolution of galaxies across different redshifts.
