Alessio Fanelli

CRIRES+ Spectroscopy Proves Liller 1 Formed In-Situ Within the Galactic Bulge, Not as a Captured Globular Cluster

High-resolution spectroscopic analysis of 30 red giant stars in the bulge fossil fragment Liller 1 reveals multiple stellar sub-populations with distinct metallicities and ages, consistent with self-enrichment and in-situ formation within the Galactic bulge. The absence of sodium-oxygen anticorrelation—a signature of genuine globular clusters—and abundance patterns matching the bulge field and Terzan 5 provide definitive evidence that Liller 1 did not form independently and become captured, but rather assembled directly within the bulge environment.

Besov Space Well-Posedness for Reduced Micropolar Fluid Models

This paper establishes well-posedness theory for a two-dimensional reduced model of inviscid micropolar fluids, which couples Euler-type velocity dynamics with scalar microrotation transport-diffusion. Local strong solutions are proven to exist and be unique in Besov spaces B^s_{p,1} with regularity index s ≥ 1 + 2/p, while global existence is demonstrated in the subcritical case s > 1 + 2/p. The critical regularity threshold s = 1 + 2/p remains unresolved, leaving open whether solutions persist globally at the minimal regularity boundary.

The WISSHFUL program: the highest redshift UFO discovered in a non-lensed QSO

Hardy-Type Uncertainty Principles Extended to Variable-Geometry Magnetic Schrödinger Equations

Fanelli et al. establish Hardy-type uncertainty principles and unique continuation results for covariant Schrödinger equations with variable coefficients under bounded electric and magnetic potentials. The central result shows that solutions exhibiting super-quadratic exponential decay at two distinct times must vanish identically, with an additional Hardy-type result at the quadratic exponential scale under a structural constraint on the coefficient matrix G. The work unifies two previously separate lines of research — the constant-coefficient magnetic case and the variable-coefficient non-magnetic case — by combining logarithmic convexity with Carleman estimates tailored to variable-coefficient covariant flows. New weight functions and refined commutator estimates are required to handle the interaction between the variable metric and magnetic structure, going beyond the classical Escauriaza-Kenig-Ponce-Vega framework.

NGC 6553's In-Situ Bulge Origin Confirmed via Multi-Element Chemical DNA Fingerprinting

The BulCO survey uses CRIRES/VLT near-infrared spectroscopy to chemically fingerprint 17 stellar systems in the Milky Way bulge. For NGC 6553, abundance measurements of 18 elements across 14 red giant branch stars confirm it as one of the most metal-rich globular clusters in the Galaxy ([Fe/H] = −0.20 dex) with in-situ bulge formation. The study validates both classical (α/Fe vs. Fe/H) and newly proposed ([V/Fe] and [Zn/Fe] vs. Fe/H) chemical diagnostics as discriminators of globular cluster origin, and confirms genuine multiple stellar populations via light-element spreads.

Neural-ODEs Gain Hard-Constrained Fixed Points Without Sacrificing Universality

This paper presents a constructive method for embedding exact fixed points (zero-velocity loci) into Neural-ODE velocity fields as a priori constraints, rather than as soft regularization targets. The approach rigorously confines gradient-based training to a hypothesis class that respects prescribed fixed-point locations while preserving full universal approximation capacity. Universality under arbitrary local velocity-field constraints is formally proven, and the method is validated on two physical model benchmarks. This has direct implications for scientific ML applications where equilibria, attractors, or boundary conditions must be structurally guaranteed rather than merely encouraged.

Yudovich Theory Extended to Heterogeneous Euler-Type Systems via Micropolar Fluid Reduction

This paper establishes global well-posedness at low regularity for a 2D reduced micropolar fluid model with zero viscosity, coupling an Euler-type equation for velocity with an advection-diffusion equation for a scalar microrotation field. The authors prove global existence and uniqueness of Yudovich-type solutions — weak solutions where vorticity is merely bounded (with additional integrability) and microrotation remains bounded with finite energy. This constitutes the first known extension of the classical Yudovich framework beyond the pure incompressible Euler equations to a system incorporating physical heterogeneity, opening a pathway for low-regularity analysis of more complex coupled fluid models.

Dimension-Wise Preferential Attachment Generates Power-Law Degree Distributions in Simplicial Complexes

Febbe, Fanelli, and Carletti propose a generative model for growing simplicial complexes — the mathematical structures used to represent higher-order (many-body) interactions — grounded in a preferential attachment mechanism applied independently at each simplex dimension. The model extends the classical Barabási–Albert framework beyond pairwise networks to produce power-law distributions for the generalized degree of simplices across dimensions. This addresses a recognized gap in higher-order network science: the lack of generative models that can reproduce empirically observed structural features in systems such as neural and social networks.