Research Projects

Bars and spiral arms are crucial in the evolution of disc galaxies, but their formation in galactic discs is not well understood. They are typically modelled as density waves supported by self-consistent stellar orbits, rotating with a pattern speed. However, observations do not align with theory, challenging current theories. This proposal aims to address two open problems: (1) the puzzle of purely gaseous bars in dwarf-irregular galaxies, where slowly-rotating, gaseous bars without an optical counterpart have been found in a few galaxies. This is a theoretical puzzle as gas is a collisional medium, and it cannot have self-consistent orbits sustaining the bar density wave. To solve this problem, the proposal proposes growing a gaseous bar in the gravitational potential of a slowly-rotating dark matter halo using N-body + hydrodynamical simulations. The success of this model will challenge the theory of MOND-ian dynamics, which cannot substitute for a triaxial dark matter halo necessary to solve this problem. Secondly, the proposal aims to understand the origin of spiral arms in barred-spiral galaxies. According to theories, the quadrupolar gravitational potential of a galactic bar should trigger a spiral density wave, leading to the formation of a spiral arm. However, observational studies often contradict theory, making this a mystery. The proposal will first segregate barred-spiral galaxies into Grand-design and Flocculent categories based on the nature of the spiral arm. A deep convolutional neural network will be trained to classify barred-spirals into these categories. The Mutual Information (MI) Theory will be used to study the dependence of the physical parameters of the spiral arm on the bar, providing new insights into the co-evolution of bars and spiral arms.