Reionization in HESTIA: Studying reionization in the LG through zoom simulations

Abstract

While cosmic reionization has been broadly constrained by global observables, the interplay between internal sources [Milky Way (MW), M31, and their satellites] and external ionization fronts remains poorly understood in a realistic Local Group (LG) context. To address this issue, we perform radiative transfer post-processing on the original hestia LG constrained simulation. We calibrate our source models using a uniform $1024^3$ particle, dark matter-only, hestia simulation coupled with a subgrid collapse fraction model to match the global reionization observables. These source models are then applied to the hestia zoom-in simulations, which consist of a $4096^3$ particle effective resolution in the zoom region centred on the MW and M31 haloes, which resolves haloes down to $10^8$ M${}_{\odot }$. We find that in all scenarios, reionization within the LG proceeds in an inside-out manner with the progenitors of the MW and M31 having 50 per cent of their material ionized by $z\sim 9-8.6$, significantly earlier than the global mid-point at $z\sim 7-7.7$, noting that external fronts from large-scale structure play a negligible role, even under the most permissive feedback model. We further show that present-day satellite galaxies exhibit only a weak correlation between their reionization redshift and their present-day radial distance from their host halo, with somewhat tighter trends around M31 than the MW. Finally, we find that presentday satellites whose assembly preceded the reionization of most of their $z=0$ material are systematically more massive today, suggesting that the oldest stellar populations preferentially reside in the most massive $z=0$ subhaloes.

References in corpus (19)

• Model-independent evidence in favor of an end to reionization by z~6
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Cosmological Radiative Transfer Codes Comparison Project I: The Static Density Field Tests
• On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution
• A Significantly Neutral Intergalactic Medium Around the Luminous z=7 Quasar J0252-0503
• Constraining the neutral fraction of hydrogen in the IGM at redshift 7.5
• Most of the photons that reionized the Universe came from dwarf galaxies
• The Hestia project: simulations of the Local Group
• Balancing mass and momentum in the Local Group
• The short ionizing photon mean free path at z=6 in Cosmic Dawn III, a new fully-coupled radiation-hydrodynamical simulation of the Epoch of Reionization
• Chronicling the reionization history at $6\lesssim z\lesssim 7$ with emergent quasar damping wings
• Dependence of the Local Reionization History on Halo Mass and Environment: Did Virgo Reionize the Local Group?
• Modelling a bright z = 6 galaxy at the faint end of the AGN luminosity function
• The reionization of galactic satellite populations
• The THESAN project: connecting ionized bubble sizes to their local environments during the Epoch of Reionization
• The AGORA High-resolution Galaxy Simulations Comparison Project. V: Satellite Galaxy Populations In A Cosmological Zoom-in Simulation of A Milky Way-mass Halo
• pyC${}^2$Ray: A flexible and GPU-accelerated Radiative Transfer Framework for Simulating the Cosmic Epoch of Reionization
• Reionization time of the Local Group and Local-Group-like halo pairs
• Cosmological contribution from population III stars in ultracompact minihalos