arXiv subjects

Anna Bencke

Publications and source records attributed to Anna Bencke.

4 recordsLinked to original sources

arXiv2026

Dynamics of self-gravitating halos with decaying dark matter

We study the evolution of self-gravitating spherical dark matter halos composed of dark matter particles that decay to a slightly less massive particle and a massless particle. The small kick velocity imparted to the daughter particle upon decay heats the halo. If the kick velocity is small compared with the characteristic velocity, the halo remains bound but puffs out. We also consider, for the first time, decaying halos with anisotropic initial conditions and find non-negligible effects on the resulting density profile. To simulate the halo evolution, we utilize the recently developed \texttt{NSphere} code across a broad range of decay times and kick velocities. We train an emulator to provide a mapping between the decay parameters and the relaxed density profile. We discuss how the resulting halo-scale signatures complement existing cosmological constraints on decaying dark matter and can be tested by upcoming surveys.

astro-ph.GA↗

arXiv2026

Constraints with CMB lensing on dark matter decays to massive decay products

Motivated by the recent measurements by the Dark Energy Spectroscopic Instrument (DESI) which suggest a late-time matter density approximately 5\% lower than that inferred from Planck we investigate models in which dark matter decays to two less massive, and thus warm, states. The decaying dark matter (DDM) models are parameterized by the fraction $f$ of dark matter that decays, the decay rate $Γ$, and the fraction $\varepsilon$ of the mass retained by the decay products. To efficiently explore the warm decay product regime, we employ \texttt{CLASSIER-DDM}, a modified version of the public Boltzmann solver \texttt{CLASS} that solves the perturbation equations with DDM via an integral-equation method. We consider DESI DR2 baryon acoustic oscillations and Planck 2018 CMB data including lensing, and find that DDM models are not favored over the $Λ$CDM model. This result arises because CMB lensing tightly constrains the velocity kicks imparted to decay products. For example, for $f\simeq0.5$, we find $1σ$ constraints to the decay-product kick velocities an order of $10^{-2}$ to $10^{-3}$ times the speed of light for decay redshifts from shortly after recombination until today. Nonetheless, the allowed parameter space includes models with sufficient power suppression at small-scales to potentially address dwarf galaxy anomalies. Our results also suggest that explanations for DESI that involve dark-matter decays to one massive and one massless particle will be constrained by CMB lensing.

astro-ph.CO↗

arXiv2026

Cosmological evolution with decaying dark matter: an integral-equation approach

We present CLASSIER-DDM, an extension of the Boltzmann solver CLASSIER that implements the decaying dark matter (DDM) model via its integral-equation approach. The code handles generic two-body decays of a dark matter particle into two lighter decay products with arbitrary masses, naturally encompassing both massless (dark radiation) and massive (warm) decay products, with their perturbations evaluated via integral equations solved iteratively. We describe the numerical implementation in detail, including the background evolution, the iterative perturbation evolution, and a small-scale analytic approximation. A modest number of iterations is sufficient to achieve sub-$0.1\%$ convergence in the matter power spectrum and the CMB lensing power spectrum across the observationally relevant parameter space. We find that a hundred momentum bins for the decay product perturbations are sufficient to achieve $\mathcal{O}(0.1\%)$ accuracy in the matter power spectrum today up to $k \sim 3\,{\rm Mpc}^{-1}$. The code achieves $\mathcal{O}(1\,{\rm min})$ runtimes per evaluation, requiring neither a Boltzmann hierarchy nor any fluid approximation, making parameter estimation with the DDM model numerically tractable. We also discuss the impact of DDM on cosmological observables, focusing on the case of two massive decay products. This work further establishes the integral-equation approach as a versatile and efficient framework for modeling non-cold relics in cosmological perturbation theory.

astro-ph.CO↗

arXiv2023

Hidden Symmetry in the Double Copy

We show that the Killing tensor of the Kerr spacetime has an analogue in the $\sqrt{\rm Kerr}$ gauge theory solution related to it by the classical double copy. This hidden symmetry of $\sqrt{\rm Kerr}$ leads to an additional constant of motion for color-charged point particles moving in it, implying integrability of the equation of motion. These are the gauge theory counterparts to the Carter constant and the integrability of the geodesic equation in a Kerr background.

hep-th↗