arXiv subjects

R. Della Monica

Publications and source records attributed to R. Della Monica.

3 recordsLinked to original sources

arXiv2026

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

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.

astro-ph.CO↗

arXiv2023

The optical appearance of a nonsingular de Sitter core black hole geometry under several thin disk emissions

We consider the optical appearance under a thin accretion disk of a regular black hole with a central de Sitter core implementing $\mathcal{O}(l^2/r^2)$ far-corrections to the Schwarzschild black hole. We use the choice $l=0.25M$, which satisfies recently found constraints from the motion of the S2 star around Sgr A$^*$ in this model, and which leads to thermodynamically stable black holes. As the emission model, we suitably adapt ten samples of the Standard Unbound emission profile for a monochromatic intensity in the disk's frame, which have been previously employed in the literature within the context of reproducing General Relativistic Magneto-Hydrodynamic simulations of the accretion flow. We find the usual central brightness depression surrounded by the bright ring cast by the disk's direct emission as well as two non-negligible photon ring contributions. As compared to the usual Schwarzschild solution, the relative luminosities of the latter are significantly boosted, while the size of the former is strongly decreased. We discuss the entanglement of the background geometry and the choice of emission model in generating these black hole images, as well as the capability of these modifications of Schwarzschild solution to pass present and future tests based on their optical appearance when illuminated by an accretion disk.

gr-qc↗

arXiv2022

Are nonsingular black holes with super-Planckian hair ruled out by S2 star data?

We propose a novel nonsingular black-hole spacetime representing a strong deformation of the Schwarzschild solution with mass $M$ by an additional hair $\ell$, which may be hierarchically larger than the Planck scale. Our black-hole model presents a de Sitter core and $\mathcal{O}(\ell^2/r^2)$ slow-decaying corrections to the Schwarzschild solution. Our black-hole solutions are thermodynamically preferred when $0.2 \lesssim \ell/GM \lesssim \, 0.3$ and are characterized by strong deviations in the orbits of test particles from the Schwarzschild case. In particular, we find corrections to the perihelion precession angle scaling linearly with $\ell$. We test our model using the available data for the orbits of the S2 star around $\text{SgrA}^*$. These data strongly constrain the value of the hair $\ell$, casting an upper bound on it of $\sim \, 0.47 \, GM$, but do not rule out the possible existence of regular black holes with super-Planckian hair.

gr-qc↗