Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe uniformity and time-invariance of the intra-cluster metal distribution in galaxy clusters from the IllustrisTNG simulations
233
0
0.0
(
0
)
Authors
Mark Vogelsberger
Ask ChatGPT about the research
No Arabic abstract
The distribution of metals in the intra-cluster medium encodes important information about the enrichment history and formation of galaxy clusters. Here we explore the metal content of clusters in IllustrisTNG - a new suite of galaxy formation simulations building on the Illustris project. Our cluster sample contains 20 objects in TNG100 - a ~(100 Mpc)^3 volume simulation with 2x1820^3 resolution elements, and 370 objects in TNG300 - a ~(300 Mpc)^3 volume simulation with 2x2500^3 resolution elements. The z=0 metallicity profiles agree with observations, and the enrichment history is consistent with observational data going beyond z~1, showing nearly no metallicity evolution. The abundance profiles vary only minimally within the cluster samples, especially in the outskirts with a relative scatter of ~15%. The average metallicity profile flattens towards the center, where we find a logarithmic slope of -0.1 compared to -0.5 in the outskirts. Cool core clusters have more centrally peaked metallicity profiles (~0.8 solar) compared to non-cool core systems (~0.5 solar), similar to observational trends. Si/Fe and O/Fe radial profiles follow positive gradients. The outer abundance profiles do not evolve below z~2, whereas the inner profiles flatten towards z=0. More than ~80% of the metals in the intra-cluster medium have been accreted from the proto-cluster environment, which has been enriched to ~0.1 solar already at z~2. We conclude that the intra-cluster metal distribution is uniform among our cluster sample, nearly time-invariant in the outskirts for more than 10 Gyr, and forms through a universal enrichment history.
rate research
Read More
We report results from a detailed study of the sloshing gas in the core of A496. We detect the low temperature/entropy spiral feature found in several cores, we also find that conduction between the gas in the spiral and the ambient medium must be suppressed by more than one order of magnitude with respect to Spitzer conductivity. Intriguingly, while the gas in the spiral features a higher metal abundance than the surrounding medium, it follows the entropy vs metal abundance relation defined by gas lying outside the spiral. The most plausible explanation for this behavior is that the low entropy metal rich plasma uplifted through the cluster atmosphere by sloshing, suffers little heating or mixing with the ambient medium. While sloshing appears to be capable of uplifting significant amounts of gas, the limited heat exchange and mixing between gas in and outside the spiral implies that this mechanism is not at all effective in: 1) permanently redistributing metals within the core region and 2) heating up the coolest and densest gas, thereby providing little or no contribution to staving of catastrophic cooling in cool cores.
We study a sample of 207 nearby galaxy groups and clusters observed with XMM-Newton. Key aspects of this sample include the large size, the high data quality, and the large diversity of cluster dynamical states. We determine the overall metallicity within 0.3R$_{500}$ and the radial distribution of the metals. On average, we find a mild dependence of the core metallicity with the average temperature of the system in agreement with previous results. However, we identify the cause of this mild dependence to be due to relaxed systems only; disturbed systems do not show this trend, on average. The large scatter observed in this relation is strongly associated with the dynamical state of the systems: relaxed systems have on average a higher metallicity in the core than disturbed objects. The radial profiles of relaxed systems are centrally peaked and show a steep decrease with radius, flattening beyond 0.3-0.4R$_{500}$. The metallicity of disturbed systems is also higher in the center but at much lower values than what is observed for relaxed objects. This finding is consistent with the picture that cluster mergers mix the abundance distribution by inducing large scale motions. The scatter of the radial profiles is quite large, but while for relaxed systems it decreases almost monotonically as function of the radius, for disturbed systems it shows a significant boost at large radii. Systems with a central radio source have a flatter profile indicating that central AGNs are an efficient mechanism to uplift and redistribute the metals in the ICM.
We study the impact that large-scale perturbations of (i) the matter density and (ii) the primordial gravitational potential with local primordial non-Gaussianity (PNG) have on galaxy formation using the IllustrisTNG model. We focus on the linear galaxy bias $b_1$ and the coefficient $b_phi$ of the scale-dependent bias induced by PNG, which describe the response of galaxy number counts to these two types of perturbations, respectively. We perform our study using separate universe simulations, in which the effect of the perturbations is mimicked by changes to the cosmological parameters: modified cosmic matter density for $b_1$ and modified amplitude $mathcal{A}_s$ of the primordial scalar power spectrum for $b_phi$. We find that the widely used universality relation $b_phi = 2delta_c(b_1 - 1)$ is a poor description of the bias of haloes and galaxies selected by stellar mass $M_*$, which is instead described better by $b_phi(M_*) = 2delta_c(b_1(M_*) - p)$ with $p in [0.4, 0.7]$. This is explained by the different impact that matter overdensities and local PNG have on the median stellar-to-halo-mass relation. A simple model of this impact allows us to describe the stellar mass dependence of $b_1$ and $b_phi$ fairly well. Our results also show a nontrivial relation between $b_1$ and $b_phi$ for galaxies selected by color and black hole mass accretion rate. Our results provide refined priors on $b_phi$ for local PNG constraints and forecasts using galaxy clustering. Given that the widely used universality relation underpredicts $b_phi(M_*)$, existing analyses may underestimate the true constraining power on local PNG.
The thermodynamic structure of hot gas in galaxy clusters is sensitive to astrophysical processes and typically difficult to model with galaxy formation simulations. We explore the fraction of cool-core (CC) clusters in a large sample of $370$ clusters from IllustrisTNG, examining six common CC definitions. IllustrisTNG produces continuous CC criteria distributions, the extremes of which are classified as CC and non-cool-core (NCC), and the criteria are increasingly correlated for more massive clusters. At $z=0$, the CC fractions for $2$ criteria are in reasonable agreement with the observed fractions but the other $4$ CC fractions are lower than observed. This result is partly driven by systematic differences between the simulated and observed gas fraction profiles. The simulated CC fractions with redshift show tentative agreement with the observed fractions, but linear fits demonstrate that the simulated evolution is steeper than observed. The conversion of CCs to NCCs appears to begin later and act more rapidly in the simulations. Examining the fraction of CCs and NCCs defined as relaxed we find no evidence that CCs are more relaxed, suggesting that mergers are not solely responsible for disrupting CCs. A comparison of the median thermodynamic profiles defined by different CC criteria shows that the extent to which they evolve in the cluster core is dependent on the CC criteria. We conclude that the thermodynamic structure of galaxy clusters in IllustrisTNG shares many similarities with observations, but achieving better agreement most likely requires modifications of the underlying galaxy formation model.
Recent stellar population analysis of early-type galaxy spectra has demonstrated that the low-mass galaxies in cluster centers have high [$alpha/rm Fe$] and old ages characteristic of massive galaxies and unlike the low-mass galaxy population in the outskirts of clusters and fields. This phenomenon has been termed coordinated assembly to highlight the fact that the building blocks of massive cluster central galaxies are drawn from a special subset of the overall low-mass galaxy population. Here we explore this idea in the IllustrisTNG simulations, particularly the TNG300 run, in order to understand how environment, especially cluster centers, shape the star formation histories of quiescent satellite galaxies in groups and clusters ($M_{200c,z=0}geq10^{13} M_{odot}$). Tracing histories of quenched satellite galaxies with $M_{star,z=0}geq10^{10} M_{odot}$, we find that those in more massive dark matter halos, and located closer to the primary galaxies, are quenched earlier, have shorter star formation timescales, and older stellar ages. The star formation timescale-$M_{star}$ and stellar age-$M_{star}$ scaling relations are in good agreement with observations, and are predicted to vary with halo mass and cluster-centric distance. The dependence on environment arises due to the infall histories of satellite galaxies: galaxies that are located closer to cluster centers in more massive dark matter halos at $z=0$ were accreted earlier on average. The delay between infall and quenching time is shorter for galaxies in more massive halos, and depends on the halo mass at its first accretion, showing that group pre-processing is a crucial aspect in satellite quenching.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
