What causes the gas to flow into the galactic nuclei?
Gas clouds along the bar of a galaxy can interact with each other due to forces/torques exerted by the bar. Consequently, this interaction cause gas to lose its momentum, and to get shocked which then the shocked gas starts funnelling to inner regions of the galaxies. We call this phenomenon, the gas inflows. The role of gas inflows in the evolution of galaxies is significant, inflows can change the morphology of the central regions, enhance nuclear star formation, and cause nuclear feeding, AGN feedback and quenching.
Although we understand how gas flow from the outer regions of galaxies to the central regions, due to gravitational effects (e.g. bar driven), we still are puzzled by how gas is being carried to the very core of the galaxies from the central regions.
I derive and study the gas kinematics (velocity and velocity dispersion fields of emission lines) from revolutionary data from the MUSE integral-field-unit instrument, together with dust maps and ionisation maps and search for signatures of gas inflows.
Insight into integral field units
Integral-field units are ideal instruments to capture extended objects like galaxies. They capture 2D spatial information and get the 3rd dimension from the spectrograph as wavelength information which we can use the data to study the gas with emission line and stars with absorption line diagnostics.
Check out my, Bars Conference talk slides for some more quick information and pretty pictures!
Here is the beautiful barred spiral galaxy NGC 1097. It hosts an AGN in the very centre and a nuclear ring which can be seen as the bright circle around the AGN. MUSE pointing is marked.
Example of the MUSE IFU cube.
For more information on IFUs check out the ESO page: https://www.eso.org/public/teles-instr/technology/ifu/
Hα emission line kinematics within the MUSE pointing of NGC1097. Flux (top), velocity (middle), velocity dispersion (bottom)
Diagnostic maps to study gas inflows in NGC1097. Dust extracted from MUSE continuum (left) Residual velocity after removing velocity of a modelled rotating disc (middle), Difference between different emission line tracers (right)