Detecting preheating in proto-clusters with Lyman-$α$ Forest Tomography

Abstract

Studies of low redshift galaxy clusters suggest the intra-cluster medium (ICM) has experienced non-gravitational heating during the formation phase of the clusters. Using simple phenomenological heating prescriptions, we simulate the effect of this preheating of the nascent ICM in galaxy protoclusters and examine its effect on Lyman-α (Lyα) forest tomographic maps. We analyse a series of cosmological zoom-in simulations of proto-clusters within the framework of the Lyα transmission-dark matter (DM) density distribution. We find that the more energy is injected into the proto-ICM at z = 3, the more the distribution at high DM density tilts towards higher Lyα transmission. This effect has been confirmed in both low-resolution simulations adopting a preheating scheme based on entropy floors, as well as in higher-resolution simulations with another scheme based on energy floors. The evolution of the slope of this distribution is shown to vary with redshift. The methodology developed here can be applied to current and upcoming Lyα forest tomographic survey data to help constrain feedback models in galaxy proto-clusters.

Constraining the Fluctuating Gunn-Peterson Approximation \\ Using Lyman-$α$ Forest Tomography at $z=2$

“…We also find weak evidence for a trend in the slope of the transmission-density distribution with the strength of the heating in the feedback model, where the distribution from Illustris, which includes the strongest feedback, results in the steepest slope. However, we note that the significance of this trend is less than 1 σ and would likely not be discernable from the global transmission-density relationship even with future surveys, although focusing on galaxy protoclusters might yield clearer constraints (Kooistra et al 2021).…”

“…As an aside, we note that while these simulation boxes are all commonly accepted as 'cosmological simulations', their volumes are still too small for most actual cosmological analyses. Most pertinently, they do not have sufficient volume to encompass at least several massive Coma-like galaxy clusters with M ∼ 10 15 M , which was why we did not use these simulations for our protocluster study in Kooistra et al (2021). Nevertheless, their volumes are adequate for the study of less extreme density regimes that make up the vast bulk of cosmic volume.…”

“…Nevertheless, the effect can be expected to be stronger in regions with large-scale overdensities of a few times the cosmic mean density that lie in the vicinity of the galaxies and AGN from which the feedback originates (e.g. Sorini et al 2018;Kooistra et al 2019Kooistra et al , 2021.…”

“…They specifically looked at the observables mentioned above in the context of existing surveys, as well as the upcoming Subaru Prime Focus Spectrograph (PFS) survey (Takada et al 2014), and found that the different feedback prescriptions particularly have an effect on the Lyα transmission contrast in the vicinity ( Mpc) of galaxies. More recently, we carried out a study (Kooistra et al 2021) of simulated 3D Lyα forest tomographic maps covering galaxy proto-clusters, i.e. mildly overdense progenitor regions of modern-day galaxy clusters.…”

“…This resulted in a 3D map of the matter density within the portion of the COSMOS field, with an effective spatial resolution of ∼5 Mpc over a redshift range of 1.6 < z < 3.2 (see also Ata et al, in prep.). This dataset can therefore uniquely be combined with the tomographic Lyα forest data from CLAMATO, which covers the same cosmic volume, in order to study the effects of heating on the intergalactic gas (see also Kooistra et al 2021) specifically in proto-cluster overdensities.…”