English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Confronting measurements of the Lyman-$\alpha$ forest with cosmologicalhydrodynamical simulations has produced stringent constraints on models ofparticle dark matter and the thermal and ionization state of the intergalacticmedium. We investigate the robustness of such models of the Lyman-$\alpha$forest, focussing on the effect of particle initial conditions on theLyman-$\alpha$ forest statistics in cosmological SPH simulations. We studymultiple particle initialization algorithms in simulations that are designed tobe identical in other respects. In agreement with the literature, we find thatthe correct linear theory evolution is obtained when a glass-like configurationis used for initial unperturbed gas particle positions alongside a regular gridconfiguration for dark matter particles and the use of non-identical initialdensity perturbations for gas and dark matter. However, we report that thisintroduces a large scale-dependent distortion in the one-dimensionalLyman-$\alpha$ transmission power spectrum at small scales ($k > 0.05$s/km).The effect is close to $50\%$ at $k\sim 0.1$s/km, and persists at higherresolution. This can severely bias inferences in parameters such as the darkmatter particle mass. By considering multiple initial conditions codes andtheir variations, we also study the impact of a variety of other assumptionsand algorithmic choices, such as adaptive softening, background radiationdensity, particle staggering, and perturbation theory accuracy, on the matterpower spectrum, the Lyman-$\alpha$ flux power spectrum, and the Lyman-$\alpha$flux PDF. This work reveals possible pathways towards more accurate theoreticalmodels of the Lyman-$\alpha$ forest to match the quality of upcomingmeasurements.

Particle initialization effects on Lyman-$\alpha$ forest statistics in cosmological SPH simulations