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ABSTRACT Dynamically relaxed galaxy clusters have long played an important role in galaxy cluster studies because it is thought their properties can be reconstructed more precisely and with less systematics. As relaxed clusters are desirable, there exist a plethora of criteria for classifying a galaxy cluster as relaxed. In this work, we examine 9 commonly used observational and theoretical morphological metrics extracted from $$54\, 000$$mock-X synthetic X-ray images of galaxy clusters taken from the IllustrisTNG, BAHAMAS, and MACSIS simulation suites. We find that the simulated criteria distributions are in reasonable agreement with the observed distributions. Many criteria distributions evolve as a function of redshift, cluster mass, numerical resolution, and subgrid physics, limiting the effectiveness of a single relaxation threshold value. All criteria are positively correlated with each other, however, the strength of the correlation is sensitive to redshift, mass, and numerical choices. Driven by the intrinsic scatter inherent to all morphological metrics and the arbitrary nature of relaxation threshold values, we find the consistency of relaxed subsets defined by the different metrics to be relatively poor. Therefore, the use of relaxed cluster subsets introduces significant selection effects that are non-trivial to resolve. 

ABSTRACT The splashback radius, Rsp, is a physically motivated halo boundary that separates infalling and collapsed matter of haloes. We study Rsp in the hydrodynamic and dark matter-only IllustrisTNG simulations. The most commonly adopted signature of Rsp is the radius at which the radial density profiles are steepest. Therefore, we explicitly optimize our density profile fit to the profile slope and find that this leads to a $$\sim 5{{\ \rm per\ cent}}$$ larger radius compared to other optimizations. We calculate Rsp for haloes with masses between 1013 and 15 M⊙ as a function of halo mass, accretion rate, and redshift. Rsp decreases with mass and with redshift for haloes of similar M200 m in agreement with previous work. We also find that Rsp/R200 m decreases with halo accretion rate. We apply our analysis to dark matter, gas, and satellite galaxies associated with haloes to investigate the observational potential of Rsp. The radius of steepest slope in gas profiles is consistently smaller than the value calculated from dark matter profiles. The steepest slope in galaxy profiles, which are often used in observations, tends to agree with dark matter profiles but is lower for less massive haloes. We compare Rsp in hydrodynamic and N-body dark matter-only simulations and do not find a significant difference caused by the addition of baryonic physics. Thus, results from dark matter-only simulations should be applicable to realistic haloes. 

Black girls are more likely to receive in-school suspension (ISS) in comparison to their non-Black peers. However, research on the effect of in-school suspension on students’ academic achievement, specifically math achievement of Black girls, is still very limited. Mathematics is an important foundational component of science, technology, and engineering fields, which are domains in which Black girls are underrepresented. Using the nationally representative Educational Longitudinal Study of 2002 (ELS:2002), this study explores the relationship between in-school suspension and the highest math course completed in a multi-level analysis of 860 Black female participants from 320 high schools. Our findings revealed that in-school suspension was associated with lower mathematics course-taking. Implications for policy, practice, and research are discussed. 

ABSTRACT Surveys in the next decade will deliver large samples of galaxy clusters that transform our understanding of their formation. Cluster astrophysics and cosmology studies will become systematics limited with samples of this magnitude. With known properties, hydrodynamical simulations of clusters provide a vital resource for investigating potential systematics. However, this is only realized if we compare simulations to observations in the correct way. Here we introduce the mock-X analysis framework, a multiwavelength tool that generates synthetic images from cosmological simulations and derives halo properties via observational methods. We detail our methods for generating optical, Compton-y and X-ray images. Outlining our synthetic X-ray image analysis method, we demonstrate the capabilities of the framework by exploring hydrostatic mass bias for the IllustrisTNG, BAHAMAS, and MACSIS simulations. Using simulation derived profiles we find an approximately constant bias b ≈ 0.13 with cluster mass, independent of hydrodynamical method, or subgrid physics. However, the hydrostatic bias derived from synthetic observations is mass-dependent, increasing to b = 0.3 for the most massive clusters. This result is driven by a single temperature fit to a spectrum produced by gas with a wide temperature distribution in quasi-pressure equilibrium. The spectroscopic temperature and mass estimate are biased low by cooler gas dominating the emission, due to its quadratic density dependence. The bias and the scatter in estimated mass remain independent of the numerical method and subgrid physics. Our results are consistent with current observations and future surveys will contain sufficient samples of massive clusters to confirm the mass dependence of the hydrostatic bias. 

ABSTRACT Feedback from accreting supermassive black holes (BHs), active galactic nuclei (AGNs), is now a cornerstone of galaxy formation models. In this work, we present radiation-hydrodynamic simulations of radiative AGN feedback using the novel arepo-rt code. A central BH emits radiation at a constant luminosity and drives an outflow via radiation pressure on dust grains. Utilizing an isolated Navarro–Frenk–White (NFW) halo we validate our set-up in the single- and multiscattering regimes, with the simulated shock front propagation in excellent agreement with the expected analytic result. For a spherically symmetric NFW halo, an examination of the simulated outflow properties with radiation collimation demonstrates a decreasing mass outflow rate and momentum flux, but increasing kinetic power and outflow velocity with decreasing opening angle. We then explore the impact of a central disc galaxy and the assumed dust model on the outflow properties. The contraction of the halo during the galaxy’s formation and modelling the production of dust grains result in a factor 100 increase in the halo’s optical depth. Radiation then couples momentum more efficiently to the gas, driving a stronger shock and producing a mass-loaded $$\sim \!10^{3}\, \mathrm{M}_{\odot }\, \mathrm{yr}^{-1}$$ outflow with a velocity of $$\sim \!2000\, \mathrm{km}\, \mathrm{s}^{-1}$$. However, the inclusion of dust destruction mechanisms, like thermal sputtering, leads to the rapid destruction of dust grains within the outflow, reducing its properties below the initial NFW halo. We conclude that radiative AGN feedback can drive outflows, but a thorough numerical and physical treatment is required to assess its true impact. 

ABSTRACT We study the evolutionary trend of the total density profile of early-type galaxies (ETGs) in IllustrisTNG. To this end, we trace ETGs from z = 0 to 4 and measure the power-law slope γ′ of the total density profile for their main progenitors. We find that their slopes γ′ steepen on average during z ∼ 4–2, then becoming shallower until z = 1, after which they remain almost constant, aside from a residual trend of becoming shallower towards z = 0. We also compare to a statistical sample of ETGs at different redshifts, selected based on their luminosity profiles and stellar masses. Due to different selection effects, the average slopes of the statistical samples follow a modified evolutionary trend. They monotonically decrease since z = 3, and after z ≈ 1, they remain nearly invariant with a mild increase towards z = 0. These evolutionary trends are mass dependent for both samples, with low-mass galaxies having in general steeper slopes than their more massive counterparts. Galaxies that transitioned to ETGs more recently have steeper mean slopes as they tend to be smaller and more compact at any given redshift. By analysing the impact of mergers and AGN feedback on the progenitors’ evolution, we conjecture a multiphase path leading to isothermality in ETGs: dissipation associated with rapid wet mergers tends to steepen γ′ from z = 4 to 2, whereas subsequent AGN feedback (especially in the kinetic mode) makes γ′ shallower again from z = 2 to 1. Afterwards, passive evolution from z = 1 to 0, mainly through gas-poor mergers, mildly decreases γ′ and maintains the overall mass distribution close to isothermal. 

Abstract. Systematic long-term studies on ecosystem dynamics are largely lacking from the East Antarctic Southern Ocean, although it is well recognized that they are indispensable to identify the ecological impacts and risks of environmental change. Here, we present a framework for establishing a long-term cross-disciplinary study on decadal timescales. We argue that the eastern Weddell Sea and the adjacent sea to the east, off Dronning Maud Land, is a particularly well suited area for such a study, since it is based on findings from previous expeditions to this region. Moreover, since climate and environmental change have so far been comparatively muted in this area, as in the eastern Antarctic in general, a systematic long-term study of its environmental and ecological state can provide a baseline of the current situation, which will be important for an assessment of future changes from their very onset, with consistent and comparable time series data underpinning and testing models and their projections. By establishing an Integrated East Antarctic Marine Research (IEAMaR) observatory, long-term changes in ocean dynamics, geochemistry, biodiversity, and ecosystem functions and services will be systematically explored and mapped through regular autonomous and ship-based synoptic surveys. An associated long-term ecological research (LTER) programme, including experimental and modelling work, will allow for studying climate-driven ecosystem changes and interactions with impacts arising from other anthropogenic activities. This integrative approach will provide a level of long-term data availability and ecosystem understanding that are imperative to determine, understand, and project the consequences of climate change and support a sound science-informed management of future conservation efforts in the Southern Ocean.