English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The primary objective of this thesis is to identify the key dynamicalmechanisms responsible for the superthin stellar discs. We use HI 21cmradio-synthesis observations and stellar photometry to construct detaileddynamical models of a sample of superthin galaxies to determine the primarymechanism responsible for the existence of superthin stellar discs in thesegalaxies. Our study is based on a sample of superthin galaxies with $\rm 10<a/b < 16$ for which H1 21cm radio-synthesis data were already available in theliterature. In addition, we had the two thinnest galaxies in our sample with$\rm a/b \sim 21$, for which we carried out Giant Meterwave Radio Telescope(GMRT) 21cm radio-synthesis observations. To identify the physical mechanismprimarily responsible for the superthin vertical structure, we carry out aPrincipal Component Analysis of the following dynamical parameters: 1) Darkmatter dominance at inner galactocentric radii given by$V_{\rm{rot}}/{(R_{c}/R_{d})}$, 2) the ratio of the vertical-to-radial stellarvelocity dispersion $(\sigma_{z,s}/\sigma_{R,s})$, 3) Disc dynamical stabilityagainst local axisymmetric perturbations $Q_{RW}$, 4) Specific angular momentumof the disc $(j_{*})$, along with $a/b$ for all superthins and the extremelythin galaxies. We note that the first two principal components explain $\sim$80$\%$ of the variation in the data, and the major contributions are from$a/b$, $Q_{RW}$ and $V_{\rm{rot}}/{(R_{c}/R_{d})}$. This possibly indicatesthat high values of the disc dynamical stability and dark matter dominance atinner galactocentric radii are fundamentally responsible for the superthinstellar discs.

HI 21 cm observations and dynamical models of superthin galaxies