Abstract We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W > 1.5 mag. We find 37 EROs ...in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W < 28 mag and photometric redshifts between 5 < z < 7, with median z = 6.9 − 1.6 + 1.0 . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W − F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like sources in all NIRCam bands. We analyze the SEDs of eight of them with MIRI and NIRSpec observations using stellar population models and active galactic nucleus (AGN) templates. We find that dusty galaxies or obscured AGNs provide similarly good SED fits but different stellar properties: massive and dusty, log M ⋆ / M ⊙ ∼ 10 and A V ≳ 3 mag, or low mass and obscured, log M ⋆ / M ⊙ ∼ 7.5 and A V ∼ 0 mag, hosting an obscured quasi-stellar object (QSO). SED modeling does not favor either scenario, but their unresolved sizes are more suggestive of AGNs. If any EROs are confirmed to have log M ⋆ / M ⊙ ≳ 10.5, it would increase the pre-JWST number density at z > 7 by up to a factor ∼60. Similarly, if they are QSOs with luminosities in the L bol > 10 45–46 erg s −1 range, their number would exceed that of bright blue QSOs by more than three orders of magnitude. Additional photometry at mid-infrared wavelengths will reveal the true nature of the red continuum emission in these EROs and will place this puzzling population in the right context of galaxy evolution.
KINEMATIC DOWNSIZING AT z ∼ 2 Simons, Raymond C.; Kassin, Susan A.; Trump, Jonathan R. ...
The Astrophysical journal,
10/2016, Letnik:
830, Številka:
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ABSTRACT We present results from a survey of the internal kinematics of 49 star-forming galaxies at in the CANDELS fields with the Keck/MOSFIRE spectrograph, Survey in the near-Infrared of Galaxies ...with Multiple position Angles (SIGMA). Kinematics (rotation velocity Vrot and gas velocity dispersion ) are measured from nebular emission lines which trace the hot ionized gas surrounding star-forming regions. We find that by , massive star-forming galaxies ( ) have assembled primitive disks: their kinematics are dominated by rotation, they are consistent with a marginally stable disk model, and they form a Tully-Fisher relation. These massive galaxies have values of that are factors of 2-5 lower than local well-ordered galaxies at similar masses. Such results are consistent with findings by other studies. We find that low-mass galaxies ( ) at this epoch are still in the early stages of disk assembly: their kinematics are often dominated by gas velocity dispersion and they fall from the Tully-Fisher relation to significantly low values of Vrot. This "kinematic downsizing" implies that the process(es) responsible for disrupting disks at have a stronger effect and/or are more active in low-mass systems. In conclusion, we find that the period of rapid stellar mass growth at is coincident with the nascent assembly of low-mass disks and the assembly and settling of high-mass disks.
We present the recent merger history of massive galaxies in a spectroscopically confirmed proto-cluster at z = 1.62. Using Hubble Space Telescope WFC3 near-infrared imaging from the Cosmic Assembly ...Near-infrared Deep Extragalactic Legacy Survey, we select cluster and z ~ 1.6 field galaxies with M sub(star) > or =, slanted 3 x 10 super(10) M sub(middot in circle), to determine the frequency of double nuclei or close companions within projected separations less than 20 kpc co-moving. We find that four out of five spectroscopically confirmed massive proto-cluster galaxies have double nuclei, and 57 super(+13) sub(-14)% of all M sub(star) > or =, slanted 3 x 10 super(10) M sub(middot in circle) cluster candidates are observed in either close pair systems or have double nuclei. In contrast, only 11% + or - 3% of the field galaxies are observed in close pair/double nuclei systems. After correcting for the contribution from random projections, the implied merger rate per massive galaxy in the proto-cluster is ~3-10 times higher than the merger rate of massive field galaxies at z ~ 1.6. Close pairs in the cluster have minor merger stellar mass ratios (M sub(primary):M sub(satellite) > or =, slanted 4), while the field pairs consist of both major and minor mergers. At least half of the cluster mergers are gas-poor, as indicated by their red colors and low 24 mu m fluxes. Two of the double-nucleated cluster members have X-ray detected active galactic nuclei with L sub(x) > 10 super(43) erg s super(-1), and are strong candidates for dual or offset super-massive black holes. We conclude that the massive z = 1.62 proto-cluster galaxies are undergoing accelerated assembly via minor mergers, and discuss the implications for galaxy evolution in proto-cluster environments.
The African Continent harbours approximately 26 Croton species. Many Croton species are used in traditional medicine in southern Africa to treat a variety of ailments including malaria, tuberculosis, ...microbial infection and inflammation. Considering the high diversity of the genus Croton, the ethnopharmacological information available on southern African species is rather limited. Furthermore, the potential for novel anti-inflammatory drug scaffolds has not previously been investigated.
The aim of the study was to evaluate the potential of four South African Croton species extracts (Croton gratissimus, Croton pseudopulchellus, Croton sylvaticus, and Croton steenkampianus) for anti-inflammatory activity targeting the TLR4 signalling pathway and to assess the potential risk for hepatotoxicity and genotoxicity using an in vitro cellomics approach.
Leaf extracts of C. gratissimus, C. pseudopulchellus, C. sylvaticus and C. steenkampianus were prepared using methanol and chloroform (1:1, v/v). The anti-inflammatory activity was determined using LPS induced nitric oxide production in RAW 264.7 macrophages, while the hepatotoxicity and genotoxicity was evaluated using multi-parameter end point analysis in C3A and Vero cells, respectively. Mitochondrial membrane potential, mitochondrial mass, oxidative stress, lysosomal content and lipid accumulation were used as markers to assess the risk for hepatotoxicity.
All four species attenuated nitric oxide production with negligible cytotoxicity. However, C. gratissimus yielded the most favorable profile. Cell density was significantly reduced in both C3A and Vero cells with the C. gratissimus extract providing a suitable toxicity profile amenable to further high content analysis. While there was no meaningful effect on mitochondrial dynamics, a strong dose dependent increase in lipid content, paralleled by an expansion of the lysosomal compartment, identifies a potential risk for steatosis. Risk for genotoxicity was investigated using the micronucleus assay which revealed a dose dependent increase in micronuclei formation. Changes in nuclear morphology and cell ploidy further strengthens the associated risk for genotoxicity and suggests the extract from C. gratissimus may function as an aneugen. Collectively, the data demonstrates that although the selected species possess anti-inflammatory components, the risk for possible hepatotoxic and genotoxic side effects may negate their prospect towards further drug development.
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•Many South African Croton species are used in traditional medicine to treat a variety of ailments including malaria, tuberculosis, microbial infection and inflammation.•Four Croton species were investigated for anti-inflammatory activity against lipopolysaccharide (LPS) induced nitric oxide production in RAW 264.7 macrophages and as well as their toxicity profiles.•The four extracts indicated the presence of phytochemical constituents with potential anti-inflammatory activity.•All four species attenuated nitric oxide production.•The four species also showed low toxicity profile in vitro, however, there was a risk associated with hepatotoxicity and genotoxicity.
The result of South Africa adopting the Twin Peaks model of financial regulation was the establishment of two regulators, namely the Prudential Authority (PA) and the Financial Sector Conduct ...Authority (FSCA). One aspect of the Financial Sector Regulation Act 9 of 2017 is that it specifically empowers the FSCA to regulate and supervise the internal dispute resolution frameworks that financial institutions are required to implement. The FSCA can publish conduct standards, which standards should be used to assist in achieving the FSCA’s objectives. One such objective includes aspects of supervising and regulating the dispute resolution framework of financial institutions. In this regard, the FSCA has produced the Conduct Standard for Banks, which deals, among other things, with certain internal dispute resolution requirements for banks. This article briefly discusses the content and practical enforceability of the Conduct Standard for Banks and considers whether this standard will adequately assist in reforming the internal dispute resolution framework of banks, such that bank customers will be sufficiently protected and treated fairly during the internal dispute resolution process. The change from a voluntary code to a statutory code strengthens the accountability of banks when there is non-compliance. Arguably, the added level of enforceability and level of compliance with set standards for dispute resolution frameworks will ensure that customer complaints are treated more fairly. However, the exact sanction for non-compliance with the provisions remains uncertain and clearer guidance is required. In the end, successful implementation of the Conduct Standard for Banks may depend on the extent to which banks decide to implement its provisions.
ABSTRACT We present an analysis of deep Hubble Space Telescope (HST) multi-band imaging of the BDF field specifically designed to identify faint companions around two of the few Ly emitting galaxies ...spectroscopically confirmed at z ∼ 7. Although separated by only 4.4 proper Mpc these galaxies cannot generate H ii regions large enough to explain the visibility of their Ly lines, thus requiring a population of fainter ionizing sources in their vicinity. We use deep HST and VLT-Hawk-I data to select z ∼ 7 Lyman break galaxies around the emitters. We select six new robust z ∼ 7 LBGs at Y ∼ 26.5-27.5 whose average spectral energy distribution is consistent with the objects being at the redshift of the close-by Ly emitters. The resulting number density of z ∼ 7 LBGs in the BDF field is a factor of approximately three to four higher than expected in random pointings of the same size. We compare these findings with cosmological hydrodynamic plus radiative transfer simulations of a universe with a half neutral IGM: we find that indeed Ly emitter pairs are only found in completely ionized regions characterized by significant LBG overdensities. Our findings match the theoretical prediction that the first ionization fronts are generated within significant galaxy overdensities and support a scenario where faint, "normal" star-forming galaxies are responsible for reionization.
We studied the chronology of galactic bulge and disc formation by analysing the relative contributions of these components to the B-band rest-frame luminosity density at different epochs. We present ...the first estimate of the evolution of the fraction of rest-frame B-band light in galactic bulges and discs since redshift z similar to 0.8. We performed a bulge-to-disc decomposition of HST/ACS images of 3266 galaxies in the zCOSMOS-bright survey with spectroscopic redshifts in the range 0.7 \textless= z \textless= 0.9. We find that the fraction of B-band light in bulges and discs is (26 4)% and (74 4)%, respectively. When compared with rest-frame B-band measurements of galaxies in the local Universe in the same mass range (10(9)M circle dot M10(11.5).M circle dot),we find that the B-band light in discs decreases by -30% from z similar to 0.7-0.9 to z 0, while the light from the bulge increases by -30% over the same period of time. We interpret this evolution as the consequence of star formation and mass assembly processes, as well as morphological transformation, which gradually shift stars formed at half the age of the Universe from star-forming late-type/irregular galaxies to earlier types and ultimately into spheroids.
The result of South Africa adopting the Twin Peaks model of financial regulation was the establishment of two regulators, namely the Prudential Authority (PA) and the Financial Sector Conduct ...Authority (FSCA). One aspect of the Financial Sector Regulation Act 9 of 2017 is that it specifically empowers the FSCA to regulate and supervise the internal dispute resolution frameworks that financial institutions are required to implement. The FSCA can publish conduct standards, which standards should be used to assist in achieving the FSCA’s objectives. One such objective includes aspects of supervising and regulating the dispute resolution framework of financial institutions. In this regard, the FSCA has produced the Conduct Standard for Banks, which deals, among other things, with certain internal dispute resolution requirements for banks. This article briefly discusses the content and practical enforceability of the Conduct Standard for Banks and considers whether this standard will adequately assist in reforming the internal dispute resolution framework of banks, such that bank customers will be sufficiently protected and treated fairly during the internal dispute resolution process. The change from a voluntary code to a statutory code strengthens the accountability of banks when there is non-compliance. Arguably, the added level of enforceability and level of compliance with set standards for dispute resolution frameworks will ensure that customer complaints are treated more fairly. However, the exact sanction for non-compliance with the provisions remains uncertain and clearer guidance is required. In the end, successful implementation of the Conduct Standard for Banks may depend on the extent to which banks decide to implement its provisions.
ABSTRACT
We present a new method to simultaneously and self-consistently model the mass distribution of galaxy clusters that combines constraints from strong lensing features, X-ray emission, and ...galaxy kinematics measurements. We are able to successfully decompose clusters into their collisionless and collisional mass components thanks to the X-ray surface brightness, as well as use the dynamics of cluster members, to obtain more accurate masses exploiting the fundamental plane of elliptical galaxies. Knowledge from all observables is included through a consistent Bayesian approach in the likelihood or in physically motivated priors. We apply this method to the galaxy cluster Abell S1063 and produce a mass model that we publicly release with this paper. The resulting mass distribution presents different ellipticities for the intra-cluster gas and the other large-scale mass components as well as deviation from elliptical symmetry in the main halo. We assess the ability of our method to recover the masses of the different elements of the cluster using a mock cluster based on a simplified version of our Abell S1063 model. Thanks to the wealth of mutliwavelength information provided by the mass model and the detected X-ray emission, we also found evidence for an ongoing merger event with gas sloshing from a smaller infalling structure into the main cluster. In agreement with previous findings, the total mass, gas profile, and gas mass fraction are all consistent with small deviations from the hydrostatic equilibrium. This new mass model for Abell S1063 is publicly available, as the lenstool extension used to construct it.
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