Abdullah Al Zaif | Searcharxiv

arXiv2026

Boson Stars in $D \ge 4$ Dimensions: Stability, Oscillation Frequencies, and Dynamical Evolutions

We construct spherically symmetric boson star solutions in $D \in \{4,5,6\}$ spacetime dimensions, considering the effects of both a quartic self-interaction term and a solitonic potential. We then perform a perturbative analysis, generalizing the pulsation equations to arbitrary dimension and potential and hence demonstrating the existence of radially stable higher-dimensional boson star solutions. In particular, we find stable solutions for $D \in {5, 6}$ with a quartic self-interaction term and for $D = 5$ with a solitonic potential We supplement these linear results with perturbed and unperturbed nonlinear dynamical evolutions in spherical symmetry, obtained using a dimensional reduction that allows us to evolve spacetimes with any number of background dimensions using the same numerical framework, while preserving the full gauge freedom of standard approaches to numerical relativity. The results of these evolutions indicate that the solutions we identify as perturbatively stable are indeed generally stable to nonlinear spherical dynamics.

gr-qc↗

arXiv2025

Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction

To date, only two strongly lensed type Ia supernovae (SNIa) have been discovered with an isolated galaxy acting as the lens: iPTF16geu and SN Zwicky. The observed image fluxes for both lens systems were inconsistent with predictions from a smooth macro lens model. A potential explanation for the anomalous flux ratios is microlensing: additional (de)magnification caused by stars and other compact objects in the lens galaxy. In this work, we combine observations of iPTF16geu and SN Zwicky with simulated microlensing magnification maps, leveraging their standardizable candle properties to constrain the lens galaxy mass slope, $η$, and the fraction of dark compact objects, $f_{\rm dc}$. The resulting mass slopes are $η= 1.70 \pm 0.07$ for iPTF16geu and $η= 1.81 \pm 0.10$ for SN Zwicky. Our results indicate no evidence for a population of dark compact objects, placing upper limits at the $95\%$ confidence level of $f_{\rm dc} < 0.25$ for iPTF16geu and $f_{\rm dc} < 0.47$ for SN Zwicky (for compact objects with masses above $ 0.02 M_{\odot}$). Assuming a constant fraction of dark compact objects for both lensed SNe, we obtain $f_{\rm dc} < 0.19$. These results highlight the potential of strongly lensed SNIa to probe the innermost parts of lens galaxies and learn about compact matter.

astro-ph.GA↗