Abstract
This review deals with the inconsistency of inner dark matter density profiles in dwarf galaxies, known as the cusp–core problem. In particular, we aim to focus on gas-poor dwarf galaxies. One of the most promising solutions to this cold dark matter small-scale issue is the stellar feedback, but it seems to be only designed for gas-rich dwarfs. However, in the regime of classical dwarfs, this core mechanism becomes negligible. Therefore, it is required to find solutions without invoking these baryonic processes as dark matter cores tend to persist even for these dwarfs, which are rather dark-matter-dominated. Here, we have presented two categories of solutions. One consists of creating dark matter cores from cusps within cold dark matter by altering the dark matter potential via perturbers. The second category gathers solutions that depict the natural emergence of dark matter cores in alternative theories. Given the wide variety of solutions, it becomes necessary to identify which mechanism dominates in the central region of galaxies by finding observational signatures left by them in order to highlight the true nature of dark matter.
Highlights
One way to constrain the nature of the dark matter (DM) is to understand how DM is distributed in galaxies
Review Plan This review aims to focus on gas-poor dwarf galaxies with M∗ = 105 − 107M, as the previous solution seems to be only designed for gas-rich dwarfs such as dwarf irregulars (dIrrs), which are still forming stars today
We argue that DM minihalos, which are still orbiting in the host dwarf, induce potential fluctuations and displace the DM potential centre
Summary
The nature of dark matter (DM) is currently one of the most fundamental and elusive mysteries in physics. Halo mergers gradually drive the halo density profiles towards a central density cusp with a sharp decline towards their outskirts [6–8] These early simulations of structure formation found a universal cuspy density profile in halos ranging from dwarf galaxies to galaxy clusters [9]. This density profile, which is almost independent of halo mass, cosmological parameters and the power spectrum of initial fluctuations, appeared to be well-described by the following form [9,10]. As the NFW profile appears to be the generic consequence of halo mergers and becomes more resilient, this might explain why this density profile is universally observed in most cosmological simulations. As the theory of the formation of our Universe dominated by the DM is established, the ΛCDM model can be confronted with observations
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have