New Delhi: Dwarf galaxies are the smallest and most abundant systems in the Universe, and are exposing major gaps in the standard cosmological model. Astronomers from the Universidad de La Laguna and the Instituto de Astrofísica de Canarias (IAC) have embarked on the INGENIO project to use high-resolution cosmological simulations to reconstruct the Local Group environment around the Milky Way, which is surrounded by a flock of small galaxies, some of which may just be visitors in the neighbourhood and not satellites. The simulations creates virtual universes that closely matches observations, with the initial conditions being constrained. The researchers aim to faithfully replicate our galactic environment, and not just simulate a generic universe.
The research reveals that the cosmological model, our understanding of the universe, accurately describes the large-scale structures, but shows systematic deviations in the small-scale structures such as dwarf galaxies. These are faint clumps of stars dominated by dark matter, and provide an ideal laboratory for studying dark matter because their dynamics are barely influenced by the stars that they contain. A crucial finding is that the central black holes, previously thought to be absent from such low-mass galaxies, play a significant role in their evolution. Even in isolated dwarf galaxies, the black holes regulate star formation, and complement stellar feedback, the two main processes that regulate the growth of galaxies.
Dark Galaxies
The astronomers are also modelling gas-rich, dark matter-dominated structures known as dark galaxies, that have formed almost no stars and remain extremely challenging to detect. Their existence was a theoretical prediction. Hubble has recently spotted one, and scientists are now starting to model dark galaxies, and comparing them to the first observational evidence. The simulations indicate that such dark galaxies may be lurking within the local group. The research addresses longstanding discrepancies between theory and observation, including the number and structural projects of dwarf galaxies and the nature of ultra-diffuse systems.