arXiv subjects

Filippo Bouchè

Publications and source records attributed to Filippo Bouchè.

5 recordsLinked to original sources

arXiv2026

Probing dynamics of extreme galaxies I. Dark matter content in ultra-diffuse galaxies

We investigate the internal structure of two galaxies from the LEWIS sample: the ultra-diffuse galaxy UDG-1 and the extended dwarf LSB-6. Both show coherent stellar rotation combined with a non-negligible fraction of random motion, with no signs of ongoing disturbance. This is the first attempt to constrain the dynamics and dark matter physics of rotation-supported UDGs through integral-field stellar kinematics. We model the galaxies as stellar spheroids with typical dwarf-like thickness embedded in spherical dark matter halos, deriving two-dimensional velocity fields that we compare with the observations in a Bayesian framework. Besides cold dark matter, we test fuzzy, self-interacting, and non-minimally coupled dark matter. The data prefer a cuspy halo in UDG-1 and a cuspless one in LSB-6. All the alternative models remain viable, although current data cannot conclusively discriminate among them. For fuzzy dark matter we obtain mutually consistent boson masses, $m_α= 4.7^{+1.8}_{-1.1} \times 10^{-22}$ eV for UDG-1 and $m_α= 6.3^{+0.4}_{-0.4} \times 10^{-22}$ eV for LSB-6. For self-interacting dark matter, LSB-6 yields a robust constraint on the velocity-weighted cross section, $\langle σv\rangle/m = 14.3^{+2.0}_{-1.9}$ cm$^2$ km g$^{-1}$ s$^{-1}$. For non-minimally coupled dark matter we derive upper bounds on the coupling length, implying marginal deviations from $Λ$CDM. Regardless of the model, both galaxies exhibit a dark matter content comparable with halos of typical dwarf galaxies with similar stellar masses. Together with stellar population analyses and globular cluster information, these results support a scenario in which UDG-1 and LSB-6 originate from puffed-up dwarfs. This work is the first in a series exploiting kinematic data of extremely low-surface-brightness galaxies to test fundamental physics, from dark matter to modified theories of gravity.

astro-ph.GA↗

arXiv2026

Weak lensing higher-order statistics to disentangle modified gravity and massive neutrinos

Going beyond second order in weak lensing (WL) statistics is known to break degeneracies among cosmological parameters. We take a step further here, investigating whether higher-order statistics (HOS) in weak lensing can disentangle among General Relativity (GR) and modified gravity (MG), also taking into account the presence of massive neutrinos. To this end, we rely on mock convergence maps obtained from GR and $f(R)$ gravity N - body simulations, and we look for MG signatures in a wide set of higher-order WL probes. We rely on different metrics to quantify the discriminatory power of each probe, also varying the measurement setup. We find out that WL HOS can indeed disentangle MG and GR also in the presence of massive neutrinos.

astro-ph.CO↗

arXiv2024

Testing non-local gravity through Ultra-Diffuse Galaxies kinematics

The emergence of the Ultra-Diffuse Galaxies in recent years has posed a severe challenge to the galaxy formation models as well as the Extended Theories of Gravity. The existence of both dark matter lacking and dark matter dominated systems within the same family of astrophysical objects indeed requires the gravity models to be versatile enough to describe very different gravitational regimes. In this work, we study a non-local extension of the theory of General Relativity that has drawn increasing attention in recent years due to its capability to account for the late time cosmic acceleration without introducing any dark energy fluid. We leverage the kinematic data of three Ultra-Diffuse Galaxies: NGC 1052-DF2 and NGC 1052-DF4, which are dark matter lacking, and Dragonfly 44, which exhibits a highly dominant dark matter component. Our analysis shows that the non-local corrections to the Newtonian potential do not affect the kinematic predictions, hence no spoiling effects emerge when the Non-local Gravity model serves as a dark energy model. We additionally provide the minimum value that the characteristic non-local radii can reach at these mass scales.

gr-qc↗

arXiv2023

Addressing Cosmological Tensions by Non-Local Gravity

Alternative cosmological models have been under deep scrutiny in recent years, aiming to address the main shortcomings of the $Λ$CDM model. Moreover, as the accuracy of cosmological surveys improved, new tensions have risen between the model-dependent analysis of the Cosmic Microwave Background and lower redshift probes. Within this framework, we review two quantum-inspired non-locally extended theories of gravity, whose main cosmological feature is a geometrically driven accelerated expansion. The models are especially investigated in light of the Hubble and growth tension, and promising features emerge for the Deser--Woodard one. On the one hand, the cosmological analysis of the phenomenological formulation of the model shows a lowered growth of structures but an equivalent background with respect to $Λ$CDM. On the other hand, the study of the lensing features at the galaxy cluster scale of a new formulation of non-local cosmology, based on Noether symmetries, makes room for the possibility of alleviating both the $H_0$ and $σ_8$ tension. However, the urgent need for a screening mechanism arises for this non-local theory of gravity.

astro-ph.CO↗

arXiv2022

Testing non-local gravity by clusters of galaxies

Extended theories of gravity have been extensively investigated during the last thirty years, aiming at fixing infrared and ultraviolet shortcomings of General Relativity and of the associated $Λ$CDM cosmological model. Recently, non-local theories of gravity have drawn increasing attention due to their potential to ameliorate both the ultraviolet and infrared behavior of gravitational interaction. In particular, Integral Kernel theories of Gravity provide a viable mechanism to explain the late time cosmic acceleration so as to avoid the introduction of any form of unknown dark energy. On the other hand, these models represent a natural link towards quantum gravity. Here, we study a scalar-tensor equivalent model of General Relativity corrected with non-local terms, where corrections are selected by the existence of Noether symmetries. After performing the weak field limit and generalizing the results to extended mass distributions, we analyse the non-local model at galaxy cluster scales, by comparing the theoretical predictions with gravitational lensing observations from the CLASH program. We obtain agreement with data at the same level of statistical significance as General Relativity. We also provide constraints for the Navarro--Frenk--White parameters and lower bounds for the non-local length scales. The results are finally compared with those from the literature.

gr-qc↗