Introducing the Science of Galactoseismology

Computer simulation of gas distribution (left) and stars (right) after the Milky Way is perturbed by a dwarf satellite galaxy.

Radio astronomers have previously observed ripples in neutral hydrogen on the outskirts of the Milky Way Galaxy. Now Sukanya Chakrabarti (Rochester Institute of Technology) and collaborators have used Flamingos-2 spectra to hint at their source: a dwarf galaxy identified by its Cepheid stars. The total mass – including dark matter – determines the “ringing” effect that can be observed later (by us now). Future observations of additional stars in various regions (associated with different dwarf galaxy companions of the Milky Way) may provide better measurements of the global dark matter content of the Milky Way. This work was featured at a press conference during the recent American Astronomical Society meeting, and the Gemini website provides more information including animated simulations of such interactions.