Formation and relaxation of halos in the context of wave DM particles evolving on a background of neutrino condensate

Abstract

We investigate the formation and relaxation of dark matter halos in the context of wave dark matter particles evolving on a background of neutrino condensate. To this aim, we solved numerically the Schrodinger-Poisson system to model the dynamical evolution of ultralight bosonic dark matter particles in the presence of neutrino condensate. The latter appears as an additional source of the gravitational field in the Poisson equation, while its dynamical evolution and interaction with the environment are neglected. We found that, depending by the value of the cutoff parameter, the presence of the background neutrino condensate can affect the formation and relaxation of wave dark matter halos. Nevertheless, for value of the cutoff of the order of a few eV, the two species can coexist showing only marginal differences with the only-wave dark matter case. These results open to the possibility of investigate about more complex cosmological scenarios involving the formation of dark matter halos.

Figures (5)

• Figure 1: The figure shows a specific but representative configuration of the initial conditions: $n_c = 20$ and $M = 5\times10^8 M_\odot$. The left, middle, and right snapshots show equatorial slices of the merger evolution at 0.0, 3.0 and 13 Gyr, respectively. In the right panel, the inset shows the innermost region of the virialized halo with the solitonic core.
• Figure 2: The figure depicts the radial mean mass density profile averaged over the simulations (blue line), and also shows the radial mass density profiles emerging from each of the 100 simulations (light-grey lines). We overplot the solitonic mass density profile in Equation \ref{['eq:soliton']} with a central density of $\rho_0 \sim 7 \times 10^7 M_\odot/\text{kpc}^3$ and a solitonic core radius of $r_c = 550 \, \text{pc}$, as the black dashed line. Starting from the break in the inner slope occurring at $\sim 3.5 r_c$, the outermost slope follows a NFW-like profile emerging when making an azimuthal average of the quantum fluctuations due to the interference pattern of the wavefunction.
• Figure 3: The figure illustrates the final state after 13 Gyrs of evolution of a specific realization of the initial conditions. The equatorial snapshots show the final state of the evolution of only $\psi$DM and in the case of neutrino-$\psi$DM simulations with different values of the cutoff parameters (as reported on top of each panel), for comparison. The insets show the innermost region of the halo with the solitonic core that emerges in all simulations except for the highest value of $\Lambda$ taken into consideration. All plots use the same color scale for the density, as reported in the last plot.
• Figure 4: The figure depicts the mass density profile of the halos corresponding to different values of $\Lambda$. As black circular point, we depicted the results from the $\psi$DM simulation, while as blue squares, light blue triangles, orange diamonds, coral nablas and red stars, we depicted the results of the new simulations for the values of $\Lambda$ equal to 1, 5, 50 ,100 and 500 eV, respectively. The main differences for the highest value of the cutoff appear in the central value of the mass density and at the transition point.
• Figure 5: The figure depicts the final halo mass density profiles for the standrad $\psi$DM (dashed black line), and for $\Lambda= 1$ eV (magenta line), $\Lambda= 3$ eV (green line), and $\Lambda= 5$ eV (blue line), respectively. All profile show an inner solitonic core and an outer NFW-like mass density distribution. In the lower panel, we show the relative difference with the $\psi$DM-only mass density profile which oscillates between a few percent up to about 13% due to the different radius of the transition between the two regions.