ABSTRACT
The role of galactic wind recycling represents one of the largest unknowns in galaxy evolution, as any contribution of recycling to galaxy growth is largely degenerate with the inflow rates ...of first-time infalling material, and the rates with which outflowing gas and metals are driven from galaxies. We present measurements of the efficiency of wind recycling from the eagle cosmological simulation project, leveraging the statistical power of large-volume simulations that reproduce a realistic galaxy population. We study wind recycling at the halo scale, i.e. gas that has been ejected beyond the halo virial radius, and at the galaxy scale, i.e. gas that has been ejected from the interstellar medium to at least $\approx 10 \, {{\ \rm per\ cent}}$ of the virial radius. Galaxy-scale wind recycling is generally inefficient, with a characteristic return time-scale that is comparable to or longer than a Hubble time, and with an efficiency that clearly peaks at the characteristic halo mass of $M_{200} = 10^{12} \, \mathrm{M_\odot }$. Correspondingly, the majority of gas being accreted on to galaxies in eagle is infalling for the first time. Recycling is more efficient at the halo scale, with values that differ by orders of magnitude from those assumed by semi-analytical galaxy formation models. Differences in the efficiency of wind recycling with other hydrodynamical simulations are currently difficult to assess, but are likely smaller. We find that cumulative first-time gas accretion rates at the virial radius are reduced relative to the expectation from dark matter accretion for haloes with mass $M_{200} \lt 10^{12} \, \mathrm{M_\odot }$, indicating efficient preventative feedback on halo scales.
Galactic outflow rates in the EAGLE simulations Mitchell, Peter D; Schaye, Joop; Bower, Richard G ...
Monthly notices of the Royal Astronomical Society,
2020, Letnik:
494, Številka:
3
Journal Article
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ABSTRACT
We present measurements of galactic outflow rates from the eagle suite of cosmological simulations. We find that gas is removed from the interstellar medium (ISM) of central galaxies with a ...dimensionless mass loading factor that scales approximately with circular velocity as $V_{\mathrm{c}}^{-3/2}$ in the low-mass regime where stellar feedback dominates. Feedback from active galactic nuclei causes an upturn in the mass loading for halo masses ${\gt}10^{12} \, \mathrm{M_\odot }$. We find that more gas outflows through the halo virial radius than is removed from the ISM of galaxies, particularly at low redshifts, implying substantial mass loading within the circumgalactic medium. Outflow velocities span a wide range at a given halo mass/redshift, and on average increase positively with redshift and halo mass up to $M_{200} \sim 10^{12} \, \mathrm{M_\odot }$. Outflows exhibit a bimodal flow pattern on circumgalactic scales, aligned with the galactic minor axis. We present a number of like-for-like comparisons to outflow rates from other recent cosmological hydrodynamical simulations, and show that comparing the propagation of galactic winds as a function of radius reveals substantial discrepancies between different models. Relative to some other simulations, eagle favours a scenario for stellar feedback where agreement with the galaxy stellar mass function is achieved by removing smaller amounts of gas from the ISM, but with galactic winds that then propagate and entrain ambient gas out to larger radii.
Studies investigating environmental enrichment have shown that exposure to enhanced sensory, cognitive, motor and social stimulation results in behavioural, cellular and molecular alterations in ...animal models. However, the evidence-base for the neurophysiological impact from environmental enrichment in humans has not been widely examined. This paper, which considers the built environment as one significant component of environmental enrichment, draws together evidence on the impact of the design of interior spaces on human emotion.
With no robust models currently available to evaluate how built environment design impacts our emotional states, this systematic review consolidates research that has measured correlates of emotion in interior settings using measures recording either autonomic nervous system (ANS) and/or central nervous system (CNS) activity in conjunction with self-reporting to indicate conscious perception. This paper aims to assess what we know, what methodologies exist and if consistencies can be seen across previously published studies.
The review found 237 records, of which 16 met abstract selection criteria. Only seven studies (across eight papers) met full-text selection criteria. Due to the vast differences in the methodologies applied, a comprehensive synthesis was not possible; highlighting the gap in controlled studies in this field of research.
As Post Occupancy Evaluations (POEs) of the built environment currently focus on the physical safety and environmental performance of buildings, this review helps inform the techniques and protocols that can be applied when evaluating the emotional effect of built environment exposure.
Caption: Four design characteristics in the studies reviewed explored a range of objective techniques. These included: electroencephalography (EEG); functional magnetic resonance imaging (fMRI); functional near infrared spectroscopy (fNIRS); electrocardiography (ECG); heart rate (HR); blood pressure (BP), and; skin conductance resonance (SCR). EEG and fMRI studies revealed modulation of neural activity across the parietal (PL) and occipital (OL) lobes. Specific regions of modulation within the temporal lobe included the superior temporal gyrus (STG) and medial temporal gyrus (MTG), while the frontopolar cortex (FPC), superior frontal gyrus (SFG) and middle frontal gyrus (MFG) were identified across the frontal lobe. Other regions of modulated activity included the sensorimotor cortex (SMR), precuneus (PN), posterior cingulate cortex (PCC), anterior cingulate cortex (ACC), parahippocampus (PH) and global pallidus (GP). Display omitted
•Reviewed impact visual properties of interior built environments have on emotion.•Limited studies conducted & broad array of methodological & reporting procedures.•Screened 237 records, 16 selected & total of 7 studies met inclusion criteria.•Design characteristics explored: form; height & enclosure; furniture style; materiality.•Varied brain activity; all studies showed a measurable affect to visual properties.
How supernova explosions power galactic winds Creasey, Peter; Theuns, Tom; Bower, Richard G
Monthly notices of the Royal Astronomical Society,
03/2013, Letnik:
429, Številka:
3
Journal Article
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Feedback from supernovae is an essential aspect of galaxy formation. In order to improve subgrid models of feedback, we perform a series of numerical experiments to investigate how supernova ...explosions shape the interstellar medium (ISM) in a disc galaxy and power a galactic wind. We use the flash hydrodynamic code to model a simplified ISM, including gravity, hydrodynamics, radiative cooling above 104 K and star formation that reproduces the Kennicutt-Schmidt relation. By simulating a small patch of the ISM in a tall box perpendicular to the disc, we obtain subparsec resolution allowing us to resolve individual supernova events. The hot interiors of supernova explosions combine into larger bubbles that sweep-up the initially hydrostatic ISM into a dense, warm cloudy medium, enveloped by a much hotter and tenuous medium, all phases in near pressure equilibrium. The unbound hot phase develops into an outflow with wind speed increasing with distance as it accelerates from the disc. We follow the launch region of the galactic wind, where hot gas entrains and ablates warm ISM clouds leading to significantly increased mass loading of the flow, although we do not follow this material as it interacts with the galactic halo.
We run a large grid of simulations in which we vary gas surface density, gas fraction and star formation rate in order to investigate the dependencies of the mass loading,
. In the cases with the most effective outflows, we observe β = 4; however, in other cases we find β < 1. We find that outflows are more efficient in discs with lower surface densities or gas fractions. A simple model in which the warm cloudy medium is the barrier that limits the expansion of the blast wave reproduces the scaling of outflow properties with disc parameters at high star formation rates. We extend the scaling relations derived from an ISM patch to infer an effective mass loading for a galaxy with an exponential disc, finding that the mass loading depends on circular velocity as β∝V
− α
d with α 2.5 for a model which fits the Tully-Fisher relation. Such a scaling is often assumed in phenomenological models of galactic winds in order to reproduce the flat faint end slope of the mass function. Our normalization is in approximate agreement with observed estimates of the mass loading for the Milky Way. The scaling we find sets the investigation of galaxy winds on a new footing, providing a physically motivated subgrid description of winds that can be implemented in cosmological hydrodynamic simulations and phenomenological models.
Abstract
We introduce the Hydrangea simulations, a suite of 24 cosmological hydrodynamic zoom-in simulations of massive galaxy clusters (M
200c = 1014–1015.4 M⊙) with baryon particle masses of ∼106 ...M⊙. Designed to study the impact of the cluster environment on galaxy formation, they are a key part of the ‘Cluster–EAGLE’ project. They use a galaxy formation model developed for the EAGLE project, which has been shown to yield both realistic field galaxies and hot gas fractions of galaxy groups consistent with observations. The total stellar mass content of the simulated clusters agrees with observations, but central cluster galaxies are too massive, by up to 0.6 dex. Passive satellite fractions are higher than in the field, and at stellar masses M
star > 1010 M⊙, this environmental effect is quantitatively consistent with observations. The predicted satellite stellar mass function matches data from local cluster surveys. Normalized to total mass, there are fewer low-mass (M
star ≲ 1010 M⊙) galaxies within the virial radius of clusters than in the field, primarily due to star formation quenching. Conversely, the simulations predict an overabundance of massive galaxies in clusters compared to the field that persists to their far outskirts (>5 r
200c). This is caused by a significantly increased stellar mass fraction of (sub-)haloes in the cluster environment, by up to ∼0.3 dex even well beyond r
200c. Haloes near clusters are also more concentrated than equally massive field haloes, but these two effects are largely uncorrelated.
ABSTRACT
We exploit EAGLE, a cosmological hydrodynamical simulation, to reproduce the selection of the observed submillimetre (submm) galaxy population by selecting the model galaxies at z ≥ 1 with ...mock submm fluxes $S_{850\, \mu \mathrm{m}}$ ≥ 1 mJy. We find a reasonable agreement between the model galaxies within this sample and the properties of the observed submm population, such as their star formation rates (SFRs) at z < 3, redshift distribution, and many integrated galaxy properties. We find that the median redshift of the $S_{850\, \mu \mathrm{m}}$ ≥ 1 mJy model population is z ≈ 2.5, and that they are massive galaxies (M* ∼ 1011 M⊙) with high dust masses (Mdust ∼ 108 M⊙), gas fractions (fgas ≈ 50 per cent), and SFRs ($\dot{M}_* \approx 100$ M⊙ yr−1). In addition, we find that they have major and minor merger fractions similar to the general population, suggesting that mergers are not the sole driver of the high SFRs in the model submm galaxies. Instead, the $S_{850\, \mu \mathrm{m}}$ ≥ 1 mJy model galaxies yield high SFRs primarily because they maintain a significant gas reservoir as a result of hosting an undermassive black hole relative to comparably massive galaxies. Not all ‘highly star-forming’ ($\dot{M}_* \ge 80$ M⊙ yr−1) eagle galaxies have submm fluxes $S_{850\, \mu \mathrm{m}}$ ≥ 1 mJy. We investigate the nature of these highly star-forming ‘Submm-Faint’ galaxies (i.e. $\dot{M}_* \ge 80$ M⊙ yr−1 but $S_{850\, \mu \mathrm{m}}$ < 1 mJy) and find that they are similar to the model submm galaxies, being gas rich and hosting undermassive black holes. However, they are also typically at higher redshifts (z > 4) and are lower mass (M* ∼ 1010 M⊙). These typically higher redshift galaxies show stronger evidence for having been triggered by major mergers, and critically, they are likely missed by most current submm surveys due to their higher dust temperatures and lower dust masses.
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