arXiv subjects

M. Fasano

Publications and source records attributed to M. Fasano.

3 recordsLinked to original sources

arXiv2023

Modeling the dynamics of an oil drop driven by a surface acoustic wave in the underlying substrate

We present a theoretical study, supported by simulations and experiments, on the spreading of a silicone oil drop under MHz-frequency surface acoustic wave (SAW) excitation in the underlying solid substrate. Our time-dependent theoretical model uses the long wave approach and considers interactions between fluid dynamics and acoustic driving. While similar methods have analyzed micron-scale oil and water film dynamics under SAW excitation, acoustic forcing was linked to boundary layer flow, specifically Schlichting and Rayleigh streaming, and acoustic radiation pressure. For the macroscopic drops in this study, acoustic forcing arises from Reynolds stress variations in the liquid due to changes in the intensity of the acoustic field leaking from the SAW beneath the drop and the viscous dissipation of the leaked wave. Contributions from Schlichting and Rayleigh streaming are negligible in this case. Both experiments and simulations show that after an initial phase where the oil drop deforms to accommodate acoustic stress, it accelerates, achieving nearly constant speed over time, leaving a thin wetting layer. Our model indicates that the steady speed of the drop results from the quasi-steady shape of its body. The drop speed depends on drop size and SAW intensity. Its steady shape and speed are further clarified by a simplified traveling wave-type model that highlights various physical effects. Although the agreement between experiment and theory on drop speed is qualitative, the results' trend regarding SAW amplitude variations suggests that the model realistically incorporates the primary physical effects driving drop dynamics.

physics.flu-dyn↗

arXiv2022

Hint for a TeV neutrino emission from the Galactic Ridge with ANTARES

Interactions of cosmic ray protons, atomic nuclei, and electrons in the interstellar medium in the inner part of the Milky Way produce a $\gamma$-ray flux from the Galactic Ridge. If the $\gamma$-ray emission is dominated by proton and nuclei interactions, a neutrino flux comparable to the $\gamma$-ray flux is expected from the same sky region. Data collected by the ANTARES neutrino telescope are used to constrain the neutrino flux from the Galactic Ridge in the 1-100 TeV energy range. Neutrino events reconstructed both as tracks and showers are considered in the analysis and the selection is optimized for the search of an excess in the region $|l| < 30\deg$, $|b| < 2\deg$. The expected background in the search region is estimated using an off-zone region with similar sky coverage. Neutrino signal originating from a power-law spectrum with spectral index ranging from $\Gamma_\nu=1$ to $4$ is simulated in both channels. The observed energy distributions are fitted to constrain the neutrino emission from the Ridge. The energy distributions in the signal region are inconsistent with the background expectation at $\sim 96\%$ confidence level. The mild excess over the background is consistent with a neutrino flux with a power law with a spectral index $2.45^{+0.22}_{-0.34}$ and a flux normalization $dN_\nu/dE_\nu = 4.0^{+2.7}_{-2.0} \times 10^{-16} \text{GeV}^{-1} \text{cm}^{-2} \text{s}^{-1} \text{sr}^{-1}$ at 40 TeV reference energy. Such flux is consistent with the expected neutrino signal if the bulk of the observed $\gamma$-ray flux from the Galactic Ridge originates from interactions of cosmic ray protons and nuclei with a power-law spectrum extending well into the PeV energy range.

astro-ph.HE↗

arXiv2022

Review of the online analyses of multi-messenger alerts and electromagnetic transient events with the ANTARES neutrino telescope

By constantly monitoring at least one complete hemisphere of the sky, neutrino telescopes are well designed to detect neutrinos emitted by transient astrophysical events. Real-time searches with the ANTARES telescope have been performed to look for neutrino candidates coincident with gamma-ray bursts detected by the Swift and Fermi satellites, highenergy neutrino events registered by IceCube, transient events from blazars monitored by HAWC, photon-neutrino coincidences by AMON notices and gravitational wave candidates observed by LIGO/Virgo. By requiring temporal coincidence, this approach increases the sensitivity and the significance of a potential discovery. Thanks to the good angular accuracy of neutrino candidates reconstructed with the ANTARES telescope, a coincident detection can also improve the positioning area of non-well localised triggers such as those detected by gravitational wave interferometers. This paper summarises the results of the follow-up performed by the ANTARES telescope between 01/2014 and 02/2022, which corresponds to the end of the data taking period.

astro-ph.HE↗