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This article explores themes of fertility and fecundity in Peter Paul Rubens' work and investigates their role in a peculiar Rubensian category of subject, somewhere between landscape and myth, which can perhaps be described as 'mythological genre'. Here we see the ancient gods of nature inhabiting the countryside and engaged in their 'everyday' activities, though, as in The feast of Venus (Vienna, Kunsthistorisches Museum), their presence is usually sensed rather than seen by any human characters depicted alongside them. A particular focus of the article is one of Rubens' most personal works, the Nymphs and satyrs gathering fruit (Madrid, Museo del Prado). It was his happy invention to give the nymphs, satyrs and even the old Silenus the job of collecting fruit together, to keep the cornucopia – symbol of abundance and fecundity – in a state of constant overflow. It has not been realised, however, that Rubens had a classical source for the idea of Silenus and the satyrs helping the nymphs gather apples: a passage in Propertius' Elegies (II.32.37-40). The poetry of Propertius was especially familiar to Rubens' circle as Justus Lipsius planned an edition of the poet's work. Moreover, the lines had been the subject of a notable emendation by Joseph Justus Scaliger, as well as an extensive discussion by Lipsius in his Antiquae lectiones (III). Rubens was surely familiar with the Propertius passage, whether he came across it in his reading or in his conversations on ancient literature and customs with his brother, Philip, Lipsius' favourite pupil. In Nymphs and satyrs , the poet's lines seem to have helped inspire a joyous celebration of the earth's fruitfulness by the gods of nature themselves. [ABSTRACT FROM AUTHOR]

The focus of this paper is a large painting in the Kunsthistorisches Museum in Vienna, often attributed to Anthony Van Dyck in collaboration with Frans Snijders, which illustrates a fish market with figures engaged in a purchase. Clearly not a simple 'genre' subject, the theme of this painting has hitherto proved a puzzle. That it turns out to be a classical story involving a mullet, the Emperor Tiberius and two rival ancient gourmets, confirms the idea, argued from other evidence, that, though Van Dyck appears to have been involved in the execution of the painting, it was his master, Peter Paul Rubens, who was the inventor of the theme and the composition. The painting is thus another example of Rubens's fruitful collaboration with his friend, the animal and still-life painter, Frans Snijders. Like the Discovery of Philopoemen (Madrid, Museo del Prado) and Pythagoras Advocating Vegetarianism (Royal Collection), it combines a lavish display of foodstuff by Snijders with a novel, and ingeniously apt, classical theme. [ABSTRACT FROM AUTHOR]

The role of major mergers in galaxy evolution remains a key open question. Existing empirical merger identification methods use non-parametric and subjective visual classifications that can pose systematic challenges to constraining merger histories. As a first step towards overcoming these challenges, we develop and share publicly a new python -based software tool that identifies and extracts the flux-wise and area-wise significant contiguous regions from the model-subtracted residual images produced by popular parametric light-profile fitting tools (e.g. galfit). Using Hubble Space Telescope (HST) H -band single-Sérsic residual images of 17 CANDELS galaxies, we demonstrate the tools ability to measure the surface brightness and improve the qualitative identification of a variety of common residual features (disc structures, spiral substructures, plausible tidal features, and strong gravitational arcs). We test our method on synthetic HST observations of a z  ∼ 1.5 major merger from the VELA hydrodynamic simulations. We extract H -band residual features corresponding to the birth, growth, and fading of tidal features during different stages and viewing orientations at CANDELS depths and resolution. We find that the extracted features at shallow depths have noisy visual appearance and are susceptible to viewing angle effects. For a VELA z  ∼ 3 major merger, we find that James Webb Space Telescope NIRCam observations can probe high-redshift tidal features with considerable advantage over existing HST capabilities. Further quantitative analysis of plausible tidal features extracted with our new software hold promise for the robust identification of hallmark merger signatures and corresponding improvements to merger rate constraints. [ABSTRACT FROM AUTHOR]

We analyze the resolved stellar populations of 473 massive star-forming galaxies at 0.7 < z < 1.5, with multi-wavelength broadband imaging from CANDELS and Hα surface brightness profiles at the same kiloparsec resolution from 3D-HST. Together, this unique data set sheds light on how the assembled stellar mass is distributed within galaxies, and where new stars are being formed. We find the Hα morphologies to resemble more closely those observed in the ACS I band than in the WFC3 H band, especially for the larger systems. We next derive a novel prescription for Hα dust corrections, which accounts for extra extinction toward H II regions. The prescription leads to consistent star formation rate (SFR) estimates and reproduces the observed relation between the Hα/UV luminosity ratio and visual extinction, on both a pixel-by-pixel and a galaxy-integrated level. We find the surface density of star formation to correlate with the surface density of assembled stellar mass for spatially resolved regions within galaxies, akin to the so-called “main sequence of star formation” established on a galaxy-integrated level. Deviations from this relation toward lower equivalent widths are found in the inner regions of galaxies. Clumps and spiral features, on the other hand, are associated with enhanced Hα equivalent widths, bluer colors, and higher specific SFRs compared to the underlying disk. Their Hα/UV luminosity ratio is lower than that of the underlying disk, suggesting that the ACS clump selection preferentially picks up those regions of elevated star formation activity that are the least obscured by dust. Our analysis emphasizes that monochromatic studies of galaxy structure can be severely limited by mass-to-light ratio variations due to dust and spatially inhomogeneous star formation histories. [ABSTRACT FROM AUTHOR]

A 75.9-kg, 3.5-year-old male Irish Wolfhound dog with a 2–3-week history of gagging and eating difficulties was referred to the University of Florida Veterinary Medical Hospital (Gainesville, Florida) for evaluation of a large cranial mediastinal mass suspected to be a thymoma or lymphosarcoma. The patient had 4 months of nearly 10 kg progressive weight loss with severe flank sensitivity and radiographically apparent lumbar vertebral changes interpreted as discospondylitis. Lab work revealed hyperglobulinemia, mild proteinuria, normal T4, negative Brucella canis titer, and negative blood and urine bacterial cultures. A thoracotomy revealed a nonresectable, destructive, space-occupying mediastinal mass resulting in euthanasia without surgical recovery. Biopsies from the mass were collected during surgery for histology. Microscopic examination revealed extensive granulomatous cellulitis and lymphadenitis characterized by central cavitated necrotic areas containing debris and degenerate neutrophils, intermediate zones of fibrovascular proliferation with marked mixed inflammation, peripheral fibrosis, frequent multinucleated macrophages, and scattered mineralization. The necrotic material contained dense mats of 2 µm wide by 8–15 µm long fungal hyphae with parallel walls, acute angle branching, frequent septae, and occasional bulb-like dilations. DNA sequencing and phylogenetic analysis of the internal transcribed spacer region confirmed the presence of a fungus in the Inonotus tropicalis group. Inonotus tropicalis is primarily a wood decay fungus that is found on dead wood from angiosperms in tropical and subtropical habitats. Isolates of the I. tropicalis group have been detected a few times from immunosuppressed human beings with X-linked granulomatous disease. [ABSTRACT FROM PUBLISHER]

Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 < z < 2.5 selected from CANDELS are used to reconstruct and model their intrinsic shapes. The sample is selected on the basis of multiple rest-frame colors to reflect low star-formation activity. We demonstrate that these galaxies as an ensemble are dust-poor and transparent and therefore likely have smooth light profiles, similar to visually classified early-type galaxies. Similar to their present-day counterparts, the z > 1 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by the random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a ∼ 0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z > 1 early-type galaxies. We find that the proportion of oblate versus triaxial galaxies depends both on the galaxies’ stellar mass, and—at a given mass—on redshift. For present-day and z < 1 early-type galaxies the oblate fraction strongly depends on galaxy mass. At z > 1, this trend is much weaker over the mass range explored here (1010 < M∗/M⊙ < 1011), because the oblate fraction among massive (M∗ ∼ 1011 M⊙) was much higher in the past: 0.59 ± 0.10 at z > 1, compared to 0.20 ± 0.02 at z ∼ 0.1. When combined with previous findings that the number density and sizes of early-type galaxies substantially increase over the same redshift range, this can be explained by the gradual emergence of merger-produced elliptical galaxies, at the expense of the destruction of pre-existing disks that were common among their high-redshift progenitors. In contrast, the oblate fraction among low-mass early-type galaxies (log(M∗/M⊙) < 10.5) increased toward the present, from z = 0 to 0.38 ± 0.11 at z > 1 to 0.72 ± 0.06 at z = 0. We speculate that this lower incidence of disks at early cosmic times can be attributed to two factors: low-mass, star-forming progenitors at z > 1 were not settled into stable disks to the same degree as at later cosmic times, and the stripping of gas from star-forming disk galaxies in dense environments is an increasingly important process at lower redshifts. [ABSTRACT FROM AUTHOR]

We study the environmental dependence of color, stellar mass, and morphology by comparing galaxies in a forming cluster to those in the field at z = 1.6 with Hubble Space Telescope near-infrared imaging in the CANDELS/UDS field. We quantify the morphology of the galaxies using the effective radius, reff , and Sérsic index, n. In both the cluster and field, approximately half of the bulge-dominated galaxies (n > 2) reside on the red sequence of the color-magnitude diagram, and most disk-dominated galaxies (n < 2) have colors expected for star-forming galaxies. There is weak evidence that cluster galaxies have redder rest-frame U-B colors and higher stellar masses compared to the field. Star-forming galaxies in both the cluster and field show no significant differences in their morphologies. In contrast, there is evidence that quiescent galaxies in the cluster have larger median effective radii and smaller Sérsic indices compared to the field with a significance of 2σ. These differences are most pronounced for galaxies at clustercentric distances 1Mpc< Rproj < 1.5Mpc, which have low Sérsic indices and possibly larger effective radii, more consistent with star-forming galaxies at this epoch and in contrast to other quiescent galaxies. We argue that star-forming galaxies are processed under the influence of the cluster environment at distances greater than the cluster-halo virial radius. Our results are consistent with models where gas accretion onto these galaxies is suppressed from processes associated with the cluster environment. [ABSTRACT FROM AUTHOR]

We have made a serendipitous discovery of a massive (~5 × 1011M⊙) cD galaxy at z = 1.096 in a candidate-rich cluster in the Hubble Ultra Deep Field (HUDF) area of GOODS-South. This brightest cluster galaxy (BCG) is themost distant cD galaxy confirmed to date. Ultra-deep HST/WFC3 images reveal an extended envelope starting from ∼10 kpc and reaching ∼70 kpc in radius along the semimajor axis. The spectral energy distributions indicate that both its inner component and outer envelope are composed of an old, passively evolving (specific star formation rate <10−4 Gyr−1) stellar population. The cD galaxy lies on the same mass–size relation as the bulk of quiescent galaxies at similar redshifts. The cD galaxy has a higher stellar mass surface density (∼M∗/R250) but a similar velocity dispersion (~√M∗/R50) to those of more massive, nearby cDs. If the cD galaxy is one of the progenitors of today's more massive cDs, its size (R50) and stellar mass have had to increase on average by factors of 3.4±1.1 and 3.3±1.3 over the past ∼8 Gyr, respectively. Such increases in size and stellar mass without being accompanied by significant increases in velocity dispersion are consistent with evolutionary scenarios driven by both major and minor dissipationless (dry) mergers. If such cD envelopes originate from dry mergers, our discovery of evenone example proves that some BCGs entered the dry merger phase at epochs earlier than z = 1. Our data match theoretical models which predict that the continuance of dry mergers at z < 1 can result in structures similar to those of massive cD galaxies seen today. Moreover, our discovery is a surprise given that the extreme depth of the HUDF is essential to reveal such an extended cD envelope at z > 1 and, yet, the HUDF covers only a minuscule region of sky (∼3.1 × 10−8). Adding that cDs are rare, our serendipitous discovery hints that such cDs may bemore common than expected, perhaps even ubiquitous. Images reaching HUDF depths of more area (especially with cluster BCGs at z > 1) are needed to confirm this conjecture. [ABSTRACT FROM AUTHOR]

We combine high-resolution Hubble Space Telescope/WFC3 images with multi-wavelength photometry to track the evolution of structure and activity of massive (M" > 1010M☉) galaxies at redshifts z = 1.4-3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We detect compact, star-forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates (SFRs) qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5-3. At z ≳ 2, cSFGs present SFR = 100-200M☉ yr-1, yet their specific star formation rates (sSFR ~ 10-9 yr-1) are typically half that of other massive SFGs at the same epoch, and host X-ray luminous active galactic nuclei (AGNs) 30 times (~30%) more frequently. These properties suggest that cSFGs are formed by gas-rich processes (mergers or disk-instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 108 yr). The cSFGs are continuously being formed at z = 2-3 and fade to cQGs down to z ~ 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary tracks of QG formation: an early (z ≳ 2), formation path of rapidly quenched cSFGs fading into cQGs that later enlarge within the quiescent phase, and a late-arrival (z ≳ 2) path in which larger SFGs form extended QGs without passing through a compact state. [ABSTRACT FROM AUTHOR]

We present Hubble Space Telescope Wide Field Camera 3 (WFC3) slitless grism spectroscopy of 28 emission-line galaxies at z ~ 2, in the GOODS-S region of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The high sensitivity of these grism observations, with > 1σ detections of emission lines to f > 2.5 x 10-18 erg s-1 cm-2 means that the galaxies in the sample are typically ~7 times less massive (median M* = 109.5 M⊙) than previously studied z ~ 2 emission-line galaxies. Despite their lower mass, the galaxies have [OIII]/Hβ ratios which are very similar to previously studied z ~ 2 galaxies and much higher than the typical emission-line ratios of local galaxies. The WFC3 grism allows for unique studies of spatial gradients in emission lines, and we stack the two-dimensional spectra of the galaxies for this purpose. In the stacked data the [O III] emission line is more spatially concentrated than the Hβ emission line with 98.1% confidence. We additionally stack the X-ray data (all sources are individually undetected), and find that the average L[OIII]/L0.5-10keV ratio is intermediate between typical z ~ 0 obscured active galaxies and star-forming galaxies. Together the compactness of the stacked [OIII] spatial profile and the stacked X-ray data suggest that at least some of these low-mass, low-metallicity galaxies harbor weak active galactic nuclei. [ABSTRACT FROM AUTHOR]

We analyze the dependence of galaxy structure (size and Sérsic index) and mode of star formation (ΣSFR and SFRIR/SFRUV) on the position of galaxies in the star formation rate (SFR) versus mass diagram. Our sample comprises roughly 640,000 galaxies at z ~ 0.1, 130,000 galaxies at z ~ 1, and 36,000 galaxies at z ~ 2. Structural measurements for all but the z ~ 0.1 galaxies are based on Hubble Space Telescope imaging, and SFRs are derived using a Herschel-calibrated ladder of SFR indicators. We find that a correlation between the structure and stellar population of galaxies (i.e., a "Hubble sequence") is already in place since at least z ~ 2.5. At all epochs, typical star-forming galaxies on the main sequence are well approximated by exponential disks, while the profiles of quiescent galaxies are better described by de Vaucouleurs profiles. In the upper envelope of the main sequence, the relation between the SFR and Sérsic index reverses, suggesting a rapid buildup of the central mass concentration in these starbursting outliers. We observe quiescent, moderately and highly star-forming systems to co-exist over an order of magnitude or more in stellar mass. At each mass and redshift, galaxies on the main sequence have the largest size. The rate of size growth correlates with specific SFR, and so does SSFR at each redshift. A simple model using an empirically determined star formation law and metallicity scaling, in combination with an assumed geometry for dust and stars, is able to relate the observed ΣSFR and SFRIR/SFRUV, provided a more patchy dust geometry is assumed for high-redshift galaxies. [ABSTRACT FROM AUTHOR]

We present uncontaminated rest-frame u - R colors of 78 X-ray-selected active galactic nucleus (AGN) hosts at 0.5 < z < i.5 in the Chandra Deep Fields measured with Hubble Space Telescope (HST)/Advanced Camera for Surveys/NICMOS and Very Large Telescope/ISAAC imaging. We also present spatially resolved NUV - R color gradients for a subsample of AGN hosts imaged by HST/Wide Field Camera 3 (WFC3). Integrated, uncorrected photometry is not reliable for comparing the mean properties of soft and hard AGN host galaxies at z ~ 1 due to color contamination from point-source AGN emission. We use a cloning simulation to develop a calibration between concentration and this color contamination and use this to correct host galaxy colors. The mean u - R color of the unobscured/soft hosts beyond ~6 kpc is statistically equivalent to that of the obscured/hard hosts (the soft sources are 0.09 4± 0.16 mag bluer). Furthermore, the rest-frame V - J colors of the obscured and unobscured hosts beyond ~6 kpc are statistically equivalent, suggesting that the two populations have similar distributions of dust extinction. For the WFC3/infrared sample, the mean NUV - R color gradients of unobscured and obscured sources differ by less than ~0.5 mag for r > 1.1 kpc. These three observations imply that AGN obscuration is uncorrelated with the star formation rate beyond ~1 kpc. These observations favor a unification scenario for intermediate-luminosity AGNs in which obscuration is determined geometrically. Scenarios in which the majority of intermediate-luminosity AGNs at z ~ 1 are undergoing rapid, galaxy-wide quenching due to AGN-driven feedback processes are disfavored. [ABSTRACT FROM AUTHOR]

We compare multi-wavelength star formation rate (SFR) indicators out to z ~ 3 in the GOODS-South field. Our analysis uniquely combines U to 8 µm photometry from FIREWORKS, MIPS 24 µm and PACS 70, 100, and 160 µm photometry from the PEP, and Hα spectroscopy from the SINS survey. We describe a set of conversions that lead to a continuity across SFR indicators. A luminosity-independent conversion from 24/um to total infrared luminosity yields estimates of LIR that are in the median consistent with the LIR derived from PACS photometry, albeit with significant scatter. Dust correction methods perform well at low-to-intermediate levels of star formation. They fail to recover the total amount of star formation in systems with large SFRIR/SFRUV ratios, typically occuring at the highest SFRs (SFRUV+IR ≳ 100 M⊙ yr-1) and redshifts (z ≳ 2.5) probed. Finally, we confirm that Hα-based SFRs at 1.5 < z < 2.6 are consistent with SFRSED and SFRUV+IR provided extra attenuation toward H II regions is taken into account (AV,neb = AV,continuum/0.44). With the cross-calibrated SFR indicators in hand, we perform a consistency check on the star formation histories inferred from spectral energy distribution (SED) modeling. We compare the observed SFR-M relations and mass functions at a range of redshifts to equivalents that are computed by evolving lower redshift galaxies backward in time. We find evidence for underestimated stellar ages when no stringent constraints on formation epoch are applied in SED modeling. We demonstrate how resolved SED modeling, or alternatively deep UV data, may help to overcome this bias. The age bias is most severe for galaxies with young stellar populations and reduces toward older systems. Finally, our analysis suggests that SFHs typically vary on timescales that are long (at least several 100 Myr) compared to the galaxies' dynamical time. [ABSTRACT FROM AUTHOR]

Using Spitzer-Multiband Imaging Photometer 24 µm imaging and extensive Keck spectroscopy, we examine the nature of the obscured star-forming population in three clusters and three groups at z ~ 0.9. These six systems are the primary components of the C11604 supercluster, the largest structure imaged by Spitzer at redshifts approaching unity. We find that the average density of 24 µm detected galaxies within the CI 1604 clusters is nearly twice that of the surrounding field and that this overdensity scales with the cluster's dynamical state. The 24 µm bright members often appear optically unremarkable and exhibit only moderate [O II] line emission due to severe obscuration. Their spatial distribution suggests that they are an infalling population, but an examination of their spectral properties, morphologies, and optical colors indicates that they are not simply analogs of the field population that have yet to be quenched. Using stacked composite spectra, we find that the 24 µm detected cluster and group galaxies exhibit elevated levels of Balmer absorption compared with galaxies undergoing normal, continuous star formation. A similar excess is not observed in field galaxies with equivalent infrared luminosities, indicating a greater fraction of the detected cluster and group members have experienced a burst of star formation in the recent past compared to their counterparts in the field. Our results suggest that gas-rich galaxies at high redshift experience a temporary increase in their star formation activity as they assemble into denser environments. Using Hubble Space Telescope Advanced Camera for Surveys imaging, we find that disturbed morphologies are common among the 24 µm detected cluster and group members and become more prevalent in regions of higher galaxy density. We conclude that mergers are the dominant triggering mechanism responsible for the enhanced star formation found in the C11604 groups, while a mix of harassment and mergers are likely driving the activity of the cluster galaxies. [ABSTRACT FROM AUTHOR]

The article focuses on the painting "Moses’s Ethiopian Wife," done by Flemish painter Jacob Jordaens circa 1650. The author explores both Jewish and Catholic religious accounts of Moses marrying a black woman, specifically in the "Jewish Antiquities," written by Jewish historian Josephus, and German reformist Martin Luther's "Bible" translation. She also explores contradictory literature regarding the race of Moses's wife written by Protestant leader John Calvin. A discussion of race represented in contemporary period art is also presented.

The article discusses about Ludovico Sforza, Duke of Milan and one of the wealthiest and most powerful princes of Renaissance Italy. He was the second son of Francesco Sforza and was famed as patron of Leonardo da Vinci and other artists. He was called il Moro due to his dark skinned complexion. It is emphasized that Ludovico had a seal of the head of a moor, in a headband, which looks very much the same with a heraldic blackamoor profile. The author also stresses that such moorish imagery which features on documents and even on persons connected with Ludovico. An example of this moorish imagery is the letter L (for Ludovicus) that shows the headband with a striped gypsy decoration on the document granting a concession from Ludovico to the Crivelli family.

The article focuses on Italian painter Paolo Veronese's drawing of a black boy eating at a table during a feast. The painting depicts Veronese's mode of representing blacks, which is found to contrast all expectations in showing the boy seated at rather than standing by the table, eating rather than serving. It is inferred that it is uncommon to find examples of the artist who draws heads from life for use in narrative compositions. However, Veronese's work was found to intend to record a live model posed in exactly the attitude and situation for a projected painting.

The article discusses the contrasting views on the skin color of the Greek mythological figure Andromeda. It examines works that indicated Andromeda as a black or a white Ethiopian woman. It explores the interpretation of Andromeda in the romance "Aethiopica," by Heliodorus. According to the author, Heliodorus' indication of Andromeda as a white Ethiopian was probably influenced by the images he saw in ancient paintings. Meanwhile, mythographer Ovid indicated that Andromeda is a black woman. The black Andromeda indication of Ovid has captivated the attention of few artists, the author noted. She cites some paintings depicting black Andromeda.

The article highlights on the works of seventeenth-century Flemish and European painter Peter Paul Rubens that include the drawing called "Hermathena." It is a drawing that depicts a combination of two person taken as one, an original example of this was Rubens' third drawing, a conjunction of Mercury and Minerva. The drawing or design have been the source of various interpretation from various artists and it has been taken into account, that they question the authenticity of Rubens' original work. Nevertheless, it has been made as an emblem and devices by others to signify oneness.

The article focuses on the drawing by Peter Paul Rubens, which was described as "Alcibiades coming drunk into the Feast of Philosophers" by Jonathan Richardson. Richardson's description was based on the episode towards the end of Plato's "Symposium" when the debate on love is abruptly defused with the arrival of intoxicated Alcibiades. The author declares that the drawing is the early sheet in the Metropolitan Museum in New York which bears Richardson's mark of ownership and Ruben's inscription. Relationship of the drawing to the painting of "The Trojans departing for Italy" was also discussed.

Evaluates studies on taxonomy and validity of subtest profiles on the Kauffman Assessment Battery for Children (K-ABC). Most common subtest patterns on K-ABC; Benefits of the core profile taxonomy; Examination of whether children with learning disabilities (LD) and mental retardation showed unusual subtest patterns; Q methodology application.

Chloroform Hepatotoxicity in the Mongolian Gerbil. EBEL, R. E., BARLOW, R., and MCGRATH, E. A. (1987). . , 207–216. CHCl hepatotoxicity was studied in the male Mongolian gerbil and compared to that in the male Sprague–Dawley strain rat. Based on elevations in serum transaminase activities in response to CHCl exposure, control gerbils were more sensitive to CHCl than were gerbils treated with phenobarbital, chlordecone, mirex, or 3-methylcholanthrene. The increased sensitivity of the control relative to the induced gerbil was consistent with earlier observations of CCl hepatotoxicity (Ebel, R. E., and McGrath, E. A., 1984, ., , 205–210). Microsomal enzyme concentrations or activities were not decreased in the control or induced gerbils in response to CHCl exposures of up to 200 μl/kg. At a dose of 500 μl/kg, cytochrome -450 and its reductase were decreased by about 25% in the chlordecone-induced gerbil. In contrast, chlordecone- and phenobarbital-induced rats were sensitive to CHCl as evidenced by marked elevations in serum transaminase activities, decreases in microsomal enzyme concentrations or activities, and a transient decrease in hepatic nonprotein sulfhydryl groups. Control rats were insensitive to CHCl. Histopathological changes in the livers of these animals were consistent with alterations in the biochemical parameters measured. The relationship between sensitivity to the hepatotoxic effects of CHCl and CCl was different for the gerbil and rat. [ABSTRACT FROM PUBLISHER]

Exploiting the deep high-resolution imaging of all five CANDELS fields, and accurate redshift information provided by 3D-HST, we investigate the relation between structure and stellar populations for a mass-selected sample of 6764 galaxies above 1010M☼, spanning the redshift range 0.5 < z < 2.5. For the first time, we fit two-dimensional models comprising a single Sérsic fit and two-component (i.e., bulge + disk) decompositions not only to the H-band light distributions, but also to the stellar mass maps reconstructed from resolved stellar population modeling. We confirm that the increased bulge prominence among quiescent galaxies, as reported previously based on rest-optical observations, remains in place when considering the distributions of stellar mass. Moreover, we observe an increase of the typical Sérsic index and bulge-to-total ratio (with median B/T reaching 40%-50%) among star-forming galaxies above 1011M☼. Given that quenching for these most massive systems is likely to be imminent, our findings suggest that significant bulge growth precedes a departure from the star-forming main sequence. We demonstrate that the bulge mass (and ideally knowledge of the bulge and total mass) is a more reliable predictor of the star-forming versus quiescent state of a galaxy than the total stellar mass. The same trends are predicted by the state-of-the-art, semi-analytic model by Somerville et al. In this model, bulges and black holes grow hand in hand through merging and/or disk instabilities, and feedback from active galactic nuclei shuts off star formation. Further observations will be required to pin down star formation quenching mechanisms, but our results imply that they must be internal to the galaxies and closely associated with bulge growth. [ABSTRACT FROM AUTHOR]

The shutdown of star formation in galaxies is generally termed “quenching.” Quenching may occur through a variety of processes, e.g., active galactic nucleus (AGN) feedback, stellar feedback, or the shock heating of gas in the dark matter halo. However, which mechanism(s) is, in fact, responsible for quenching is still in question. This paper addresses quenching by searching for traces of possible quenching processes through their effects on galaxy structural parameters such as stellar mass (M*), M*/re, surface stellar mass density (∼M*/r2e), and Sérsic index (n). We analyze the rest-frame U – B color correlations versus these structural parameters using a sample of galaxies in the redshift range 0.5 ⩽ z < 0.8 from the DEEP2/AEGIS survey. In addition to global radii, stellar masses, and Sérsic parameters, we also use “bulge” and “disk” photometric measurements from GIM2D fits to HST/ACS V and I images. We assess the tightness of the color relationships by measuring their “overlap regions,” defined as the area in color-parameter space in which red and blue galaxies overlap; the parameter that minimizes these overlap regions is considered to be the most effective color discriminator. We find that Sérsic index (n) has the smallest overlap region among all tested parameters and resembles a step function with a threshold value of n = 2.3. There exists, however, a significant population of outliers with blue colors yet high n values that seem to contradict this behavior; they make up ≈40% of n > 2.3 galaxies. We hypothesize that their Sérsic values may be distorted by bursts of star formation, AGNs, and/or poor fits, leading us to consider central surface stellar mass density, Σ*1 kpc, as an alternative to Sérsic index. Not only does Σ*1 kpc correct the outliers, but it also forms a tight relationship with color, suggesting that the innermost structure of galaxies is most physically linked with quenching. Furthermore, at z ∼ 0.65, the majority of the blue cloud galaxies cannot simply fade onto the red sequence since their GIM2D bulge masses are only half as large on average as the bulge masses of similar red sequence galaxies, thus demonstrating that stellar mass must absolutely increase at the centers of galaxies as they quench. We discuss a two-stage model for quenching in which galaxy star formation rates are controlled by their dark halos while they are still in the blue cloud and a second quenching process sets in later, associated with the central stellar mass buildup. The mass buildup is naturally explained by any non-axisymmetric features in the potential, such as those induced by mergers and/or disk instabilities. However, the identity of the second quenching agent is still unknown. We have placed our data catalog online. [ABSTRACT FROM AUTHOR]

We use HST/WFC3 imaging from the CANDELS Multi-Cycle Treasury Survey, in conjunction with the Sloan Digital Sky Survey, to explore the evolution of galactic structure for galaxies with stellar masses >3 × 1010M☼ from z = 2.2 to the present epoch, a time span of 10 Gyr. We explore the relationship between rest-frame optical color, stellar mass, star formation activity, and galaxy structure. We confirm the dramatic increase from z = 2.2 to the present day in the number density of non-star-forming galaxies above 3 × 1010M☼ reported by others. We further find that the vast majority of these quiescent systems have concentrated light profiles, as parameterized by the Sérsic index, and the population of concentrated galaxies grows similarly rapidly. We examine the joint distribution of star formation activity, Sérsic index, stellar mass, inferred velocity dispersion, and stellar surface density. Quiescence correlates poorly with stellar mass at all z < 2.2. Quiescence correlates well with Sérsic index at all redshifts. Quiescence correlates well with “velocity dispersion” and stellar surface density at z > 1.3, and somewhat less well at lower redshifts. Yet, there is significant scatter between quiescence and galaxy structure: while the vast majority of quiescent galaxies have prominent bulges, many of them have significant disks, and a number of bulge-dominated galaxies have significant star formation. Noting the rarity of quiescent galaxies without prominent bulges, we argue that a prominent bulge (and perhaps, by association, a supermassive black hole) is an important condition for quenching star formation on galactic scales over the last 10 Gyr, in qualitative agreement with the active galactic nucleus feedback paradigm. [ABSTRACT FROM AUTHOR]

We perform a detailed analysis of the resolved colors and stellar populations of a complete sample of 323 star-forming galaxies (SFGs) at 0.5 < z < 1.5 and 326 SFGs at 1.5 < z < 2.5 in the ERS and CANDELS-Deep region of GOODS-South. Galaxies were selected to be more massive than 1010M☼ and have specific star formation rates (SFRs) above 1/tH. We model the seven-band optical ACS + near-IR WFC3 spectral energy distributions of individual bins of pixels, accounting simultaneously for the galaxy-integrated photometric constraints available over a longer wavelength range. We analyze variations in rest-frame color, stellar surface mass density, age, and extinction as a function of galactocentric radius and local surface brightness/density, and measure structural parameters on luminosity and stellar mass maps. We find evidence for redder colors, older stellar ages, and increased dust extinction in the nuclei of galaxies. Big star-forming clumps seen in star formation tracers are less prominent or even invisible in the inferred stellar mass distributions. Off-center clumps contribute up to ∼20% to the integrated SFR, but only 7% or less to the integrated mass of all massive SFGs at z ∼ 1 and z ∼ 2, with the fractional contributions being a decreasing function of wavelength used to select the clumps. The stellar mass profiles tend to have smaller sizes and M20 coefficients, and higher concentration and Gini coefficients than the light distribution. Our results are consistent with an inside-out disk growth scenario with brief (100-200 Myr) episodic local enhancements in star formation superposed on the underlying disk. Alternatively, the young ages of off-center clumps may signal inward clump migration, provided this happens efficiently on the order of an orbital timescale. [ABSTRACT FROM AUTHOR]

We present a study on spectral energy distributions, morphologies, and star formation for an IRAC-selected extremely red object sample in the GOODS Chandra Deep Field-South. This work was enabled by new HST/WFC3 near-IR imaging from the CANDELS survey as well as the deepest available X-ray data from Chandra 4 Ms observations. This sample consists of 133 objects with the 3.6 μm limiting magnitude of [3.6] = 21.5 and is approximately complete for galaxies with M* > 1011M☼ at 1.5 ⩽ z ⩽ 2.5. We classify this sample into two types, quiescent and star-forming galaxies (SFGs), in the observed infrared color-color ([3.6]–[24] versus K – [3.6]) diagram. The further morphological study of this sample shows a consistent result with the observed color classification. The classified quiescent galaxies are bulge dominated and SFGs in the sample have disk or irregular morphologies. Our observed infrared color classification is also consistent with the rest-frame color (U – V versus V – J) classification. We also found that quiescent and SFGs are well separated in the nonparametric morphology parameter (Gini versus M20) diagram measuring their concentration and clumpiness: quiescent galaxies have a Gini coefficient higher than 0.58 and SFGs have a Gini coefficient lower than 0.58. We argue that the star formation quenching process must lead to or be accompanied by the increasing galaxy concentration. One prominent morphological feature of this sample is that disks are commonly seen in this massive galaxy sample at 1.5 ⩽ z ⩽ 2.5: 30% of quiescent galaxies and 70% of SFGs with M* > 1011M☼ have disks in their rest-frame optical morphologies. The prevalence of these extended, relatively undisturbed disks challenges the merging scenario as the main mode of massive galaxy formation. [ABSTRACT FROM AUTHOR]