EAGLE Project Research Articles

Emergence of red, star-forming galaxies (red misfits) in a ΛCDM universe

ABSTRACT We investigate the formation of red misfits (RM) using a cosmological, hydrodynamical simulation from the eagle project. Similar to observations, the RM possess less dust, higher stellar metallicities, and older stellar populations compared to blue, star-forming galaxies (BA) at the same $M_\star$. Lagrangian particle-tracking reveals that the older ages of RM have resulted from a combined effect of higher star formation efficiency (SFE), and the earlier onset and faster net depletion of their interstellar medium (ISM). For the centrals, the latter was partially due to higher efficiency of escape from ISM, driven by stronger stellar and/or active galactic nucleus feedback (depending on the mass). There was an additional contribution to this escape from gas stripping for satellite RM, as suggested by the higher group masses ($\gtrsim 0.5$ dex) and $\mathrm{H_2}/\mathrm{H}\, {\rm{\small I}}$ ratios ($\gtrsim 0.3$ dex). Moreover, accretion of circumgalactic gas (CGM) on to the galaxy has been less efficient for the satellites. On the metallicity front, the offsets are largely due to the disparity in SFE, causing varying degrees of enrichment through the mass transfers associated with stellar winds and supernovae. We ascribe this SFE disparity to the lower specific angular momentum (j) of freshly accreted CGM for RM, which ultimately manifested in the ISM kinematics due to interactions with cooling flows. The impact on $j_{\rm ism}$ was further intensified by poorer alignment with the flow’s $\vec{j}$, particularly for the satellites. Our results illuminate potential origins of RM, and motivate further exploration of this peculiar class through a synergy between observations and simulations.

Golden Eagle Populations, Movements, and Landscape Barriers: Insights from Scotland

GPS satellite tracking allows novel investigations of how golden eagles Aquila chrysaetos use the landscape at several scales and at different life history stages, including research on geographical barriers which may prevent or limit range expansion or create population/sub-population isolation. If there are significant barriers to golden eagle movements, there could be demographic and genetic consequences. Genetic studies have led investigations on the identification of sub-species, populations, and sub-populations but should be conjoined with demographic studies and dispersal movements to understand fully such designations and their geographic delimitation. Scottish eagles are genetically differentiated from continental European birds, with thousands of years of separation creating a distinct population, though without sub-species assignation. They present unique research opportunities to examine barriers to movements illustrated by satellite tracking under Scotland’s highly variable geography. We primarily examined two features, using more than seven million dispersal records from satellite tags fitted to 152 nestlings. The first was the presence of unsuitable terrestrial habitat. We found few movements across a region of largely unsuitable lowland habitat between upland regions substantially generated by geological features over 70 km apart (Highland Boundary Fault and Southern Uplands Fault). This was expected from the Golden Eagle Topography model, and presumed isolation was the premise for an ongoing reinforcement project in the south of Scotland, translocating eagles from the north (South Scotland Golden Eagle Project: SSGEP). Second was that larger expanses of water can be a barrier. We found that, for a northwestern archipelago (Outer Hebrides), isolated by ≥24 km of sea (and with prior assignation of genetical and historical separation), there were no tagged bird movements with the Inner Hebrides and/or the Highlands mainland (the main sub-population), confirming their characterisation as a second sub-population. Results on the willingness of eagles to cross open sea or sea lochs (fjords) elsewhere in Scotland were consistent on distance. While apparently weaker than the Outer Hebrides in terms of separation, the designation of a third sub-population in the south of Scotland seems appropriate. Our results validate the SSGEP, as we also observed no movement of birds across closer sea crossings from abundant Highland sources to the Southern Uplands. Based on telemetric results, we also identified where any re-colonisation of England, due to the SSGEP, is most likely to occur. We emphasise, nevertheless, that our study’s records during dispersal will be greater than the natal dispersal distances (NDDs), when birds settle to breed after dispersal, and NDDs are the better shorter arbiter for connectivity.

해방 이전 정운수의 생애와 독립운동

The primary focus of this paper is to illuminate the life and contributions of Chung Woonsoo(鄭雲樹) to the Korean independence movement and explore its significance. The period that this study focuses on is from 1903, when he was born, to right after the liberation of Korea in 1945. Chung was educated predominantly at Protestant schools during the Japanese colonial era and further pursued theological studies in the United States.
 His activism gained prominence during the Asia-Pacific War. Chung discerned the intricate link between the culmination of World War II and the restoration of Korean sovereignty. As a response, he fervently engaged in independence efforts in both America and China.
 In Washington, D.C., Chung played various roles in the Korean Commission, aiding Syngman Rhee. He embarked on campaigns to secure support and empathy from Americans for the Korean independence cause and spearheaded initiatives to highlight Korea’s quest for autonomy within the American public sphere.
 In 1944, Chung was commissioned as an officer in the U.S. Army. Subsequently, he was dispatched to China via Burma and assigned to the U.S.
 14th Air Force in 1945. During this tenure, he took part in ‘The Eagle Project’, a collaborative endeavor between the Korean Independence Army(KIA) and the U.S. Office of Strategic Services(OSS). His responsibilities fostering KIA-OSS military collaborations, training communications for KIA’s Second Detachment members, and orchestrating advance operations into Korea.
 Chung’s dedication to the independence movement was unwavering. Heemployed a gamut of strategies(from diplomacy and propaganda to direct armed resistance) in his relentless pursuit to end Japanese oppression and reinstate Korea’s sovereignty. Even though the anticipated advance operation into Korea did not materialize, Chung’s instrumental role in bolstering the collaboration between the KIA and OSS undeniably elevated the stature of both the Provisional Government of the Republic of Korea and the KIA.

Application of dimensionality reduction and clustering algorithms for the classification of kinematic morphologies of galaxies

Context. The morphological classification of galaxies is considered a relevant issue and can be approached from different points of view. The increasing growth in the size and accuracy of astronomical data sets brings with it the need for the use of automatic methods to perform these classifications. Aims. The aim of this work is to propose and evaluate a method for the automatic unsupervised classification of kinematic morphologies of galaxies that yields a meaningful clustering and captures the variations of the fundamental properties of galaxies. Methods.We obtained kinematic maps for a sample of 2064 galaxies from the largest simulation of the EAGLE project that mimics integral field spectroscopy images. These maps are the input of a dimensionality reduction algorithm followed by a clustering algorithm. We analysed the variation of physical and observational parameters among the clusters obtained from the application of this procedure to different inputs. The inputs studied in this paper are (a) line-of-sight velocity maps for the whole sample of galaxies observed at fixed inclinations; (b) line-of-sight velocity, dispersion, and flux maps together for the whole sample of galaxies observed at fixed inclinations; (c) line-of-sight velocity, dispersion, and flux maps together for two separate subsamples of edge-on galaxies with similar amount of rotation; and (d) line-of-sight velocity, dispersion, and flux maps together for galaxies from different observation angles mixed. Results. The application of the method to solely line-of-sight velocity maps achieves a clear division between slow rotators (SRs) and fast rotators (FRs) and can differentiate rotation orientation. By adding the dispersion and flux information at the input, low-rotation edge-on galaxies are separated according to their shapes and, at lower inclinations, the clustering using the three types of maps maintains the overall information obtained using only the line-of-sight velocity maps. This method still produces meaningful groups when applied to SRs and FRs separately, but in the first case the division into clusters is less clear than when the input includes a variety of morphologies. When applying the method to a mixture of galaxies observed from different inclinations, we obtain results that are similar to those in our previous experiments with the advantage that in this case the input is more realistic. In addition, our method has proven to be robust: it consistently classifies the same galaxies viewed from different inclinations.

Has JWST Already Falsified Dark-matter-driven Galaxy Formation?

The James Webb Space Telescope (JWST) discovered several luminous high-redshift galaxy candidates with stellar masses of M * ≳ 109 M ⊙ at photometric redshifts z phot ≳ 10, which allows to constrain galaxy and structure formation models. For example, Adams et al. identified the candidate ID 1514 with located at and Naidu et al. found even more distant candidates labeled as GL-z11 and GL-z13 with at and at , respectively. Assessing the computations of the IllustrisTNG (TNG50-1 and TNG100-1) and EAGLE projects, we investigate if the stellar mass buildup as predicted by the ΛCDM paradigm is consistent with these observations assuming that the early JWST calibration is correct and that the candidates are indeed located at z ≳ 10. Galaxies formed in the ΛCDM paradigm are by more than an order of magnitude less massive in stars than the observed galaxy candidates implying that the stellar mass buildup is more efficient in the early universe than predicted by the ΛCDM models. This in turn would suggest that structure formation is more enhanced at z ≳ 10 than predicted by the ΛCDM framework. We show that different star formation histories could reduce the stellar masses of the galaxy candidates alleviating the tension. Finally, we calculate the galaxy-wide initial mass function (gwIMF) of the galaxy candidates assuming the integrated galaxy IMF theory. The gwIMF becomes top-heavy for metal-poor star-forming galaxies decreasing therewith the stellar masses compared to an invariant canonical IMF.

Exploring the outskirts of the EAGLE disc galaxies

ABSTRACT Observations show that the surface brightness of disc galaxies can be well-described by a single exponential (TI), up-bending (TIII), or down-bending (TII) profiles in the outskirts. Here we characterize the mass surface densities of simulated late-type galaxies from the eagle project according to their distribution of mono-age stellar populations, the star formation activity, and angular momentum content. We find a clear correlation between the inner scale lengths and the stellar spin parameter, λ, for all three disc types with λ > 0.35. The outer scale lengths of TII and TIII discs show a positive trend with λ, albeit weaker for the latter. TII discs prefer fast rotating galaxies. With regards to the stellar age distribution, negative and U-shape age profiles are the most common for all disc types. Positive age profiles are determined by a more significant contribution of young stars in the central regions, which decrease rapidly in the outer parts. TII discs prefer relative higher contributions of old stars compared to other mono-age populations across the discs whereas TIII discs become progressively more dominated by intermediate age (2–6 Gyr) stars for increasing radius. The change in slope of the age profiles is located after the break of the mass surface density. We find evidence of larger flaring for the old stellar populations in TIII systems compared to TI and TII, which could indicate the action of other processes. Overall, the relative distributions of mono-age stellar populations and the dependence of the star formation activity on radius are found to shape the different disc types and age profiles.

On the Variation in Stellar α-enhancements of Star-forming Galaxies in the EAGLE Simulation

Abstract The ratio of α-elements to iron in galaxies holds valuable information about the star formation history (SFH) since their enrichment occurs on different timescales. The fossil record of stars in galaxies has mostly been excavated for passive galaxies, since the light of star-forming galaxies is dominated by young stars, which have much weaker atmospheric absorption features. Here we use the largest reference cosmological simulation of the EAGLE project to investigate the origin of variations in stellar α-enhancement among star-forming galaxies at z = 0, and their impact on integrated spectra. The definition of α-enhancement in a composite stellar population is ambiguous. We elucidate two definitions—termed “mean” and “galactic” α-enhancement—in more detail. While a star-forming galaxy has a high “mean” α-enhancement when its stars formed rapidly, a galaxy with a large “galactic” α-enhancement generally had a delayed SFH. We find that absorption-line strengths of Mg and Fe correlate with variations in α-enhancement. These correlations are strongest for the “galactic” α-enhancement. However, we show that these are mostly caused by other effects that are cross-correlated with α-enhancement, such as variations in the light-weighted age. This severely complicates the retrieval of α-enhancements in star-forming galaxies. The ambiguity is not severe for passive galaxies, and we confirm that spectral variations in these galaxies are caused by measurable variations in α-enhancements. We suggest that this more complex coupling between α-enhancement and SFHs can guide the interpretation of new observations of star-forming galaxies.

2-20 褐炭ガス化によるCO2フリー水素製造への取組み

2-20 褐炭ガス化によるCO2フリー水素製造への取組み

Fast galaxy bars continue to challenge standard cosmology

ABSTRACT Many observed disc galaxies harbour a central bar. In the standard cosmological paradigm, galactic bars should be slowed down by dynamical friction from the dark matter halo. This friction depends on the galaxy’s physical properties in a complex way, making it impossible to formulate analytically. Fortunately, cosmological hydrodynamical simulations provide an excellent statistical population of galaxies, letting us quantify how simulated galactic bars evolve within dark matter haloes. We measure bar strengths, lengths, and pattern speeds in barred galaxies in state-of-the-art cosmological hydrodynamical simulations of the IllustrisTNG and EAGLE projects, using techniques similar to those used observationally. We then compare our results with the largest available observational sample at redshift z = 0. We show that the tension between these simulations and observations in the ratio of corotation radius to bar length is 12.62σ (TNG50), 13.56σ (TNG100), 2.94σ (EAGLE50), and 9.69σ (EAGLE100), revealing for the first time that the significant tension reported previously persists in the recently released TNG50. The lower statistical tension in EAGLE50 is actually caused by it only having five galaxies suitable for our analysis, but all four simulations give similar statistics for the bar pattern speed distribution. In addition, the fraction of disc galaxies with bars is similar between TNG50 and TNG100, though somewhat above EAGLE100. The simulated bar fraction and its trend with stellar mass both differ greatly from observations. These dramatic disagreements cast serious doubt on whether galaxies actually have massive cold dark matter haloes, with their associated dynamical friction acting on galactic bars.

Predicting accreted satellite galaxy masses and accretion redshifts based on globular cluster orbits in the E-MOSAICS simulations

ABSTRACT The ages and metallicities of globular clusters (GCs) are known to be powerful tracers of the properties of their progenitor galaxies, enabling their use in determining the merger histories of galaxies. However, while useful in separating GCs into individual accretion events, the orbits of GC groups themselves have received less attention as probes of their progenitor galaxy properties. In this work, we use simulations of galaxies and their GC systems from the MOdelling Star cluster population Assembly In Cosmological Simulations within EAGLE project to explore how the present-day orbital properties of GCs are related to the properties of their progenitor galaxies. We find that the orbits of GCs deposited by accretion events are sensitive to the mass and merger redshift of the satellite galaxy. Earlier mergers and larger galaxy masses deposit GCs at smaller median apocentres and lower total orbital energy. The orbital properties of accreted groups of GCs can therefore be used to infer the properties of their progenitor galaxy, though there exists a degeneracy between galaxy mass and accretion time. Combining GC orbits with other tracers (GC ages, metallicities) will help to break the galaxy mass/accretion time degeneracy, enabling stronger constraints on the properties of their progenitor galaxy. In situ GCs generally orbit at lower energies (small apocentres) than accreted GCs, however they exhibit a large tail to high energies and even retrograde orbits (relative to the present-day disc), showing significant overlap with accreted GCs. Applying the results to Milky Way GCs groups suggests a merger redshift z ∼ 1.5 for the Gaia Sausage/Enceladus and z > 2 for the ‘low-energy’/Kraken group, adding further evidence that the Milky Way had two significant mergers in its past.

Numerical convergence of hydrodynamical simulations of galaxy formation: the abundance and internal structure of galaxies and their cold dark matter haloes

ABSTRACT We address the issue of numerical convergence in cosmological smoothed particle hydrodynamics simulations using a suite of runs drawn from the eagle project. Our simulations adopt subgrid models that produce realistic galaxy populations at a fiducial mass and force resolution, but systematically vary the latter in order to study their impact on galaxy properties. We provide several analytic criteria that help guide the selection of gravitational softening for hydrodynamical simulations, and present results from runs that both adhere to and deviate from them. Unlike dark matter-only simulations, hydrodynamical simulations exhibit a strong sensitivity to gravitational softening, and care must be taken when selecting numerical parameters. Our results – which focus mainly on star formation histories, galaxy stellar mass functions and sizes – illuminate three main considerations. First, softening imposes a minimum resolved escape speed, vϵ, due to the binding energy between gas particles. Runs that adopt such small softening lengths that $v_\epsilon \gtrsim 10\, {\rm km\, s^{-1}}$ (the sound speed in ionized ${\sim }10^4\, {\rm K}$ gas) suffer from reduced effects of photoheating. Secondly, feedback from stars or active galactic nuclei may suffer from numerical overcooling if the gravitational softening length is chosen below a critical value, ϵeFB. Thirdly, we note that small softening lengths exacerbate the segregation of stars and dark matter particles in halo centres, often leading to the counterintuitive result that galaxy sizes increase as softening is reduced. The structure of dark matter haloes in hydrodynamical runs respond to softening in a way that reflects the sensitivity of their galaxy populations to numerical parameters.

SDSS-IV MaNGA: the inner density slopes of nearby galaxies

ABSTRACT We derive the mass-weighted total density slopes within the effective (half-light) radius, γ′, for more than 2000 nearby galaxies from the SDSS-IV (Sloan Digital Sky Survey IV) MaNGA survey using Jeans-anisotropic-models applied to integral field unit observations. Our galaxies span a wide range of the stellar mass (109 M⊙ < M* < 1012 M⊙) and the velocity dispersion (30 km s−1 < σv < 300 km s−1). We find that for galaxies with velocity dispersion σv > 100 km s−1, the density slope has a mean value 〈γ′〉 = 2.24 and a dispersion σγ = 0.22, almost independent of velocity dispersion, consistent with previous lensing and stellar dynamical analysis. We also quantitatively confirm with high accuracy a turnover in the γ′–σv relation is present at σ ∼ 100 km s−1, below which the density slope decreases rapidly with σv, consistent with the results reported by previous analysis of ${\rm ATLAS^{\rm 3D}}$ survey. Our analysis shows that a large fraction of dwarf galaxies (below M* = 1010 M⊙) have total density slopes shallower than 1, which implies that they may reside in cold dark matter haloes with shallow density slopes. We compare our results with that of galaxies in hydrodynamical simulations of EAGLE, Illustris, and IllustrisTNG projects, and find all simulations predict shallower density slopes for massive galaxies with high σv. Finally, we explore the dependence of γ′ on the positions of galaxies in haloes, namely centrals versus satellites, and find that for the same velocity dispersion, the amplitude of γ′ is higher for satellite galaxies by about 0.1.

Assembly of spheroid-dominated galaxies in the EAGLE simulation

Context. Despite the insights gained in the last few years, our knowledge about the formation and evolution scenario for the spheroid-dominated galaxies is still incomplete. New and more powerful cosmological simulations have been developed that together with more precise observations open the possibility of more detailed study of the formation of early-type galaxies (ETGs).Aims. The aim of this work is to analyse the assembly histories of ETGs in a Λ cold dark matter cosmology, focussing on the archeological approach given by the mass-growth histories.Methods. We inspected a sample of dispersion-dominated galaxies selected from the largest volume simulation of the EAGLE project. This simulation includes a variety of physical processes such as radiative cooling, star formation (SF), metal enrichment, and stellar and active galactic nucleus (AGN) feedback. The selected sample comprised 508 spheroid-dominated galaxies classified according to their dynamical properties. Their surface brightness profile, the fundamental relations, kinematic properties, and stellar-mass growth histories are estimated and analysed. The findings are confronted with recent observations.Results. The simulated ETGs are found to globally reproduce the fundamental relations of ellipticals. All of them have an inner disc component where residual younger stellar populations (SPs) are detected. A correlation between the inner-disc fraction and the bulge-to-total ratio is reported. We find a relation between kinematics and shape that implies that dispersion-dominated galaxies with lowV/σL(whereVis the average rotational velocity andσLthe one dimensional velocity dispersion) tend to have ellipticity smaller than ∼0.5 and are dominated by old stars. On average, less massive galaxies host slightly younger stars. More massive spheroids show coeval SPs while for less massive galaxies (stellar masses lower than ∼1010 M⊙), there is a clear trend to have rejuvenated inner regions, showing an age gap between the inner and the outer regions up to ∼2 Gyr, in apparent contradiction with observational findings. We find evidences suggesting that both the existence of the disc components with SF activity in the inner region and the accretion of satellite galaxies in outer regions could contribute to the outside-in formation history in galaxies with low stellar mass. On the other hand, there are non-negligible uncertainties in the determination of the ages of old stars in observed galaxies. Stronger supernova (SN) feedback and/or the action of AGN feedback for galaxies with stellar masses lower than 1010 M⊙could contribute to prevent the SF in the inner regions.

The mass–size plane of EAGLE galaxies

Context. Current observational results show that both late- and early-type galaxies follow tight mass–size planes on which physical properties such as age, velocity dispersion, and metallicity correlate with the scatter on the plane. Aims. We study the mass–size plane of galaxies in cosmological hydrodynamical simulations, as a function of velocity dispersion, age, chemical abundances, ellipticity, and spin parameters with the aim of assessing to what extent the current cosmological paradigm can reproduce these observations and provide a physical interpretation of them. Methods. We selected a sample of well-resolved galaxies from the (100 Mpc)3 simulation of the EAGLE Project. This sample is composed of 508 spheroid-dominated galaxies and 1213 disc-dominated galaxies. The distributions of velocity dispersion, age, metallicity indicators and gradients, and spin parameters across the mass–size plane are analysed. Furthermore, we study the relation between shape and kinematic parameters. The results are compared with observations. Results. The mass-weighted ages of the EAGLE galaxies are found to vary along lines of constant velocity dispersion on the mass–size plane, except for galaxies with velocity dispersions higher than ∼150 km s−1. Negative age gradients tend to be found in extended disc galaxies in agreement with observations. However, the age distributions of early-type galaxies show a larger fraction with inverted radial profiles. The distribution of metallicity gradients does not show any clear dependence on this plane. Galaxies with similar spin parameters (λ) display larger sizes as their dynamical masses increase. Stellar-weighted ages are found to be good proxies for λ in galaxies with low ellipticity (ε). A bimodal distribution of λ is found so that the high-λ peak is dominated by discs with young stellar populations (SPs), while the second peak is mainly populated by slow rotators (λ < 0.2) with old stars. Our findings suggest that the physical processes that regulate the star formation histories in galaxies might also affect the angular moment budgets of gas and stars, and as a consequence their morphology.

Dark-matter-deficient galaxies in hydrodynamical simulations

Abstract Low-mass galaxies are expected to be dark-matter-dominated even within their central regions. Recently, two observations reported two dwarf galaxies in a group environment with very little dark matter in their central regions. We explore the population and origins of dark-matter-deficient galaxies (DMDGs) using two state-of-the-art hydrodynamical simulations, the EAGLE and Illustris projects. For all satellite galaxies with 109 < M* < 1010 M$\odot$ in groups with M200 > 1013 M$\odot$, we find that about $2.6\, {\rm per\, cent}$ of them in EAGLE, and $1.5\, {\rm per\, cent}$ in Illustris are DMDGs with dark matter fractions below $50\, {\rm per\, cent}$ inside two times the half-stellar-mass radius. We demonstrate that DMDGs are highly tidally disrupted galaxies, and that because dark matter has a higher binding energy than stars, mass loss of the dark matter is much more rapid than that of stars in DMDGs during tidal interactions. If DMDGs were confirmed in observations, they are expected in current galaxy formation models.

Energy equipartition between stellar and dark matter particles in cosmological simulations results in spurious growth of galaxy sizes

ABSTRACT The impact of 2-body scattering on the innermost density profiles of dark matter haloes is well established. We use a suite of cosmological simulations and idealized numerical experiments to show that 2-body scattering is exacerbated in situations where there are two species of unequal mass. This is a consequence of mass segregation and reflects a flow of kinetic energy from the more to less massive particles. This has important implications for the interpretation of galaxy sizes in cosmological hydrodynamic simulations, which nearly always model stars with less massive particles than are used for the dark matter. We compare idealized models as well as simulations from the eagle project that differ only in the mass resolution of the dark matter component, but keep subgrid physics, baryonic mass resolution, and gravitational force softening fixed. If the dark matter particle mass exceeds the mass of stellar particles, then galaxy sizes – quantified by their projected half-mass radii, R50 – increase systematically with time until R50 exceeds a small fraction of the redshift-dependent mean interparticle separation, l (${\rm R_{50}} \gtrsim 0.05\times l$). Our conclusions should also apply to simulations that adopt different hydrodynamic solvers, subgrid physics, or adaptive softening, but in that case may need quantitative revision. Any simulation employing a stellar-to-dark matter particle mass ratio greater than unity will escalate spurious energy transfer from dark matter to baryons on small scales.

Risk Evaluation, Design, Implementation, Instrumentation, and Verification for Crown Pillar Extraction at Pinos Altos Mine

The Santo Nino ore body at Pinos Altos Mine has been in production since 2009 using both open pit and underground mining methods. Between 2015 and 2017, an extensive study evaluated extraction strategy of the Santo Nino crown pillar. The Agnico Eagle project team evaluated geomechanical, operational, safety and economical risks before developing a comprehensive plan to extract the Santo Nino crown pillar by underground stoping. The geomechanical aspects of that study focused on interpreting in situ rock mass conditions and understanding the mechanical and hydrological/hydrogeological mechanisms influencing ground reaction during open pit and underground mine operations to make meaningful forward predictions for crown pillar extraction. Numerical modeling played a significant role in making forward predictions. To minimize uncertainty in those predictions, the model parameters were calibrated using measured pit slope deformations, back analysis of historical slope instabilities and underground observations of rock mass conditions. Ultimately, it was decided that long-hole stoping would be utilized for crown pillar extraction. The pit floor would be used as a drilling horizon, and the upper most level of the underground operations served as the mucking horizon. Various safety and operational risk mitigation strategies were developed and implemented; this included geomechanical monitoring using the in-pit radar system and numerous borehole extensometers installed underground to monitor ground deformations. The calibrated numerical model results provided valuable input for the design of the instrumentation program, and once the crown pillar came into production in late 2017, the instrumentation provided valuable data for model verification and stope design adjustments.

An EpiDoc ontological perspective: the epigraphs of the Castello Ursino Civic Museum of Catania via CIDOC CRM

The rich epigraphic heritage of the Castello Ursino Civic Museum of Catania has been studied by the EpiCUM project that encoded it in EpiDoc TEI XML, an XML based standard digital representation for cultural heritage contents. The project made the epigraphic heritage available in a digital museum: under the guise of the ‘Voci di Pietra’ exhibition, a selection of epigraphs were presented, implementing innovative presentation modalities thanks to a smart use of technological and digital means. Information contained in the epigraphs was semantically reorganized in a unique homogeneous container, the EpiONT ontology, constructed according to the Linked Open Data paradigm and to consolidated international standards. The encoding of the ancient texts, by the TEI standard and its EpiDoc subset, is wedded to the paradigmatic semantic web model for museums and cultural heritage. The EpiONT ontology is currently populated by 580 epigraphs collected in the Castello Ursino Civic Museum. Designed according to the CIDOC CRM standard, it makes use of the SKOS vocabularies of the EAGLE project concerning material, execution technique, type of inscription, and type of support of an epigraph. The EpiONT ontology additionally can handle any uncertainty in the origin and place of discovery of the epigraphs.

The abundances and properties of Dual AGN and their host galaxies in the EAGLE simulations

We look into the abundance of Dual AGN in the largest hydrodynamical simulation from the EAGLE project. We define a Dual AGN as two active black holes (BHs) with a separation below 30 kpc. We find that only 1 per cent of AGN with $\LhX\geq 10^{42}\ergs$ are part of a Dual AGN system at $z=0.8-1$. During the evolution of a typical binary BH system, the rapid variability of the hard X-ray luminosity on Myr time-scales severely limits the detectability of Dual AGN. To quantify this effect, we calculate a probability of detection, $t_{\rm on}/t_{\rm 30}$, where $t_{\rm 30}$ is the time in which the two black holes are separated at distances below 30 kpc and $t_{\rm on}$, the time that both AGN are visible (e.g. when both AGN have $\LhX\geq 10^{42}\ergs$) in this period. We find that the average fraction of visible Dual systems is 3 per cent. The visible Dual AGN distribution as a function of BH separation presents a pronounced peak at $\sim 20$ kpc that can be understood as a result of the rapid orbital decay of the host galaxies after their first encounter. We also find that $75$ per cent of the host galaxies have recently undergone or are undergoing a merger with stellar mass ratio $\geq 0.1$. Finally, we find that the fraction of visible Dual AGN increases with redshift as found in observations.

Data Release of UV to Submillimeter Broadband Fluxes for Simulated Galaxies from the EAGLE Project

Abstract We present dust-attenuated and dust emission fluxes for sufficiently resolved galaxies in the EAGLE suite of cosmological hydrodynamical simulations, calculated with the SKIRT radiative transfer code. The post-processing procedure includes specific components for star formation regions, stellar sources, and diffuse dust and takes into account stochastic heating of dust grains to obtain realistic broadband fluxes in the wavelength range from ultraviolet to submillimeter. The mock survey includes nearly half a million simulated galaxies with stellar masses above across six EAGLE models. About two-thirds of these galaxies, residing in 23 redshift bins up to z = 6, have a sufficiently resolved metallic gas distribution to derive meaningful dust attenuation and emission, with the important caveat that the same dust properties were used at all redshifts. These newly released data complement the already publicly available information about the EAGLE galaxies, which includes intrinsic properties derived by aggregating the properties of the smoothed particles representing matter in the simulation. We further provide an open-source framework of Python procedures for post-processing simulated galaxies with the radiative transfer code SKIRT. The framework allows any third party to calculate synthetic images, spectral energy distributions, and broadband fluxes for EAGLE galaxies, taking into account the effects of dust attenuation and emission.