Abstract Details

Name: GANESH N
Affiliation: Indian Institute of Science Education and Research Tirupati
Conference ID: ASI2021_535
Title : Dynamical Modelling of Spiral Arms in Low Surface Brightness galaxies
Authors and Co-Authors : Ganesh N & Arunima Banerjee, Department of Physics,Indian Institute of Science Education and Research
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : Low surface brightness galaxies (LSBs) are galaxies with central $B$-band surface brightness lying between 23 and 26 mag arcsec$^{-2}$ with a low star formation rate of 0.001 - 0.1 M$_{\odot}$ yr$^{-1}$ in spite of being gas-rich with $M_{HI}/L_B$ $\sim$ 1, possibly due to the suppression of dynamical instabilities by a dominant dark matter halo. We study the formation of local spiral arms by the swing amplification mechanism for a sample of spiral LSBs modelled as a 2-fluid system in the force field of a dark matter halo. For two of our sample LSBs, we also study the formation of a global spiral pattern as driven by a density wave as well as by the superposition of transient modes using the N-body simulation, with the galaxy modelled as a stellar disk embedded in the gravitational potential of the gas and the dark matter halo in both cases. Our results indicate that the high value of the multi-component disc dynamical stability against local axi-symmetric stabilities as indicated by $Q_N$($Q_N^{min}>2.4$) inhibits the growth of local spiral features by swing amplification, and the density wave theory study predicts a lower growth rate(0.012 $ M yr^{-1}$) when compared to high surface brightness galaxies $ 0.021 M yr^{-1}$. Interestingly, the N-body simulation seems to model the spiral features of comparable strength and pitch angle as seen in the observed images of these LSBs.