ABSTRACT
JWST imaging of the rich galaxy cluster Abell 2744 at z = 0.308 has been used by the UNCOVER team to construct mosaic images in the NIRCam filters. The exceptionally deep images in the ...(F115W, F150W, and F200W) bands reveal a large population of unresolved point-like sources across the field, the vast majority of which are globular clusters (GCs) or ultra-compact dwarfs. To the limits of our photometry, more than 10 000 such objects were measured, most of which are in the haloes of the five largest A2744 galaxies but which also include GCs around some satellite galaxies and throughout the intergalactic medium. The measured luminosity function covers almost 4 mag and follows a classic lognormal shape, though the GCLF turnover point still lies fainter than the photometric completeness limit. The colour index (F115W–F200W) in particular covers an intrinsic spread of 0.5 mag, clearly resolving the expected range of GC metallicities. The overall results are consistent with a large, normal GC population seen at a 3.5 Gyr earlier stage of dynamical evolution.
Abstract We have developed a novel method of determining 2D radial density profiles for astronomical systems of discrete objects using Voronoi tessellations. This Voronoi-based method was tested ...against the standard annulus-based method on five simulated systems of objects, following known Hubble density profiles of varying parameters and sizes. It was found that the Voronoi-based method returned radial density fits with lower uncertainties on the fitting parameters across all five systems compared to the annulus-based method. The Voronoi-based method also consistently returned more accurate estimates of the total number of objects in each system than the annulus-based method, and this accuracy increased with increasing system size. Finally, the Voronoi-based method was applied to two observed globular cluster systems around brightest cluster galaxies ESO 444-G046 and 2MASX J13272961-3123237 and the results were compared to previous results for these galaxies obtained with the annulus-based method. Again, it was found that the Voronoi-based method returned fits with lower uncertainties on the fitting parameters, and the total number of globular clusters returned are within errors of the annulus-based method estimates, however also with lower uncertainties.
ABSTRACT The advent of JWST now allows entire star cluster populations to be imaged in galaxies at cosmologically significant redshifts, bringing with it the need to apply K-corrections to their ...magnitudes and colour indices. Since the stellar populations within star clusters can be well approximated by a single age and metallicity, their spectral energy distributions are very different from those of galaxies or supernovae, and their K-corrections behave differently. We derive the photometric K-corrections versus redshift for model star clusters that cover a wide range of ages and metallicities, illustrating the results particularly for the broad-band filters on the Hubble Space Telescope/Advanced Camera for Surveys and the JWST/Near-Infrared Camera that are most commonly being used for imaging of populations of star clusters in distant galaxies. In an appendix, we introduce a webtool called rescuer (REdshifted Star ClUstERs) that can generate K-values and their uncertainties for any user-defined combination of cluster properties.
ABSTRACT An increasing body of data reveals a one-to-one linear correlation between galaxy halo mass and the total mass in its globular cluster (GC) population, , valid over five orders of magnitude. ...In this paper we explore the nature of this correlation for galaxies of different morphological types and for the subpopulations of metal-poor (blue) and metal-rich (red) GCs. For the subpopulations of different metallicity, we find and with similar scatter. The numerical values of these exponents can be derived from the detailed behavior of the red and blue GC fractions with galaxy mass and provide a self-consistent set of relations. In addition, all morphological types (E, S0, S/Irr) follow the same relation, but with a second-order trend for spiral galaxies to have a slightly higher fraction of metal-rich GCs for a given mass. These results suggest that the amount of gas available for GC formation at high redshift was in nearly direct proportion to the dark matter halo potential, in strong contrast to the markedly nonlinear behavior of total stellar mass versus halo mass. Of the few available theoretical treatments that directly discuss the formation of GCs in a hierarchical-merging framework, we find that the model of Kravtsov & Gnedin best matches these observations. They find that the blue, metal-poor GCs formed in small halos at and did so in nearly direct proportion to halo mass. Similar models addressing the formation rate of the red, more metal-rich GCs in the same detail and continuing to lower redshift are still needed for a comprehensive picture.
Data from the Hubble Space Telescope taken with the Advanced Camera for Surveys/WFC camera have been used to investigate the globular cluster (GC) populations around six giant elliptical galaxies ...that are ~40 Mpc distant. From these six fields, imaged in B and I, a total of more than 15,000 candidate GCs have been measured, of which 8000 or more are high-probability GCs. The data reach a limiting magnitude near MI -8, about 0.4 mag fainter than the GC luminosity function turnover point, and thus thoroughly cover the bright half of the GC population. Most of the individual GCs on these images are marginally resolved nonstellar objects, so King-model profiles convolved with the stellar point-spread functions are used to measure their individual total magnitudes, colors, and linear effective radii. The classic bimodal form of the GC color-magnitude distribution shows up unambiguously in all the galaxies, allowing an accurate definition of the mean colors along each of the two sequences as a function of magnitude (the mass/metallicity relation or MMR). The blue, metal-poor cluster sequence shows a clearly defined but nonlinear MMR: in this particular photometric data set the mean GC color changes smoothly from a near-vertical sequence at low luminosity (MI -9.5) to an increasingly redward slope at higher luminosity. By contrast, the red, metal-rich sequence shows little trace of an MMR and is nearly vertical at all luminosities. The form and slope of the MMR along either sequence do not depend strongly on either cluster size rh or galactocentric distance R gc. All the observed features of the present data agree with the interpretation that the MMR is created primarily by GC self-enrichment, along the lines of the quantitative model of Bailin & Harris. During the protocluster formation stage, the more massive GCs are better able to hold back the enriched products of the earliest supernovae and to seed the lower-mass stars still in formation. The 'threshold' mass at which this effect should become noticeable is near 1 million Solar masses, which is closely consistent with the transition region that is seen in the data. More generally, the data favor models in which the star formation efficiency in a protocluster is roughly independent of mass, and in which the gas retention efficiency is a strong function of mass. Correlation of the median scale sizes rh of the GCs with other parameters shows that the metal-poor clusters are consistently 17% larger than those of the metal-rich clusters, and that this difference holds at all galactocentric distances and luminosities. At the same time, cluster size scales with halo location as rh ~ R 0.11 gc, indicating that both metallicity and the external tidal environment play roles in determining the scale size of a given cluster. Lastly, both the red and blue GC components show metallicity gradients with galactocentric distance that are shallow but real: heavy-element abundance scales as Z ~ R -0.1 gc for both types.
To develop an evidence-based clinical practice guideline to assist in clinical decision making for patients with advanced hepatocellular carcinoma (HCC).
ASCO convened an Expert Panel to conduct a ...systematic review of published phase III randomized controlled trials (2007-2020) on systemic therapy for advanced HCC and provide recommended care options for this patient population.
Nine phase III randomized controlled trials met the inclusion criteria.
Atezolizumab + bevacizumab (atezo + bev) may be offered as first-line treatment of most patients with advanced HCC, Child-Pugh class A liver disease, Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-1, and following management of esophageal varices, when present, according to institutional guidelines. Where there are contraindications to atezolizumab and/or bevacizumab, tyrosine kinase inhibitors sorafenib or lenvatinib may be offered as first-line treatment of patients with advanced HCC, Child-Pugh class A liver disease, and ECOG PS 0-1. Following first-line treatment with atezo + bev, and until better data are available, second-line therapy with a tyrosine kinase inhibitor may be recommended for appropriate candidates. Following first-line therapy with sorafenib or lenvatinib, second-line therapy options for appropriate candidates include cabozantinib, regorafenib for patients who previously tolerated sorafenib, or ramucirumab (for patients with α-fetoprotein ≥ 400 ng/mL), or atezo + bev where patients did not have access to this option as first-line therapy. Pembrolizumab or nivolumab are also reasonable options for appropriate patients following sorafenib or lenvatinib. Consideration of nivolumab + ipilimumab as an option for second-line therapy and third-line therapy is discussed. Further guidance on choosing between therapy options is included within the guideline. Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines.
Solvate ionic liquids (SIL) have promising applications as electrolyte materials. Despite the broad design space of oligoether ligands, most reported SILs are based on simple tri- and tetraglyme. ...Here, we describe a computational search for complex ethers that can better stabilize SILs. Through active learning, a neural network interatomic potential is trained from density functional theory data. The learned potential fulfills two key requirements: transferability across composition space, and high speed and accuracy to find low-energy ligand-ion poses across configurational space. Candidate ether ligands for Li
, Mg
and Na
SILs with higher binding affinity and electrochemical stability than the reference compounds are identified. Lastly, their properties are related to the geometry of the coordination sphere.
In a series of three papers, Eadie et al. developed a hierarchical Bayesian method to estimate the Milky Way Galaxy's mass given a physical model for the potential, a measurement model, and kinematic ...data of test particles such as globular clusters (GCs) or halo stars in the Galaxy's halo. The Galaxy's virial mass was found to have a 95% Bayesian credible region (c.r.) of (0.67, 1.09) × 1012 M . In the present study, we test the hierarchical Bayesian method against simulated galaxies created in the McMaster Unbiased Galaxy Simulations 2 (MUGS2), for which the true mass is known. We estimate the masses of MUGS2 galaxies using GC analogs from the simulations as tracers. The analysis, completed as a blind test, recovers the true M200 of the MUGS2 galaxies within 95% Bayesian c.r. in 8 out of 18 cases. Of the 10 galaxy masses that were not recovered within the 95% c.r., a large subset have posterior distributions that occupy extreme ends of the parameter space allowed by the priors. A few incorrect mass estimates are explained by the exceptional evolution history of the galaxies. We also find evidence that the model cannot describe both the galaxies' inner and outer structure simultaneously in some cases. After removing the GC analogs associated with the galactic disks, the true masses were found more reliably (13 out of 18 were predicted within the c.r.). Finally, we discuss how representative the GC analogs are of the real GC population in the Milky Way.
The REDUCE-IT study found that patients at elevated risk for cardiovascular disease (CVD) who were already taking statins obtained a marked benefit by taking 4 g/d of eicosapentaenoic acid ethyl ...esters (icosapent ethyl, IPE; Vascepa) over about 5 years. Although approved for triglyceride (TG) lowering, IPE had only a modest TG-lowering effect in REDUCE-IT, largely because median TG levels were relatively low already. Hence the question of what mechanisms IPE might be working through is of great interest. At present, it appears that the best mechanistic candidates would be anti-platelet effects and/or anti-inflammatory effects. Whatever the cause, the powerful effects of IPE on CVD risk have renewed interest in the clinical utility of omega-3 fatty acids.
We combine a new, comprehensive database for globular cluster populations in all types of galaxies with a new calibration of galaxy halo masses based entirely on weak lensing. Correlating these two ...sets of data, we find that the mass ratio eta = M sub(GCS)/M sub(h) (total mass in globular clusters, divided by halo mass) is essentially constant at left angle bracketetaright angle bracket ~ 4 x 10 super(-5), strongly confirming earlier suggestions in the literature. Globular clusters are the only known stellar population that formed in essentially direct proportion to host galaxy halo mass. The intrinsic scatter in eta appears to be at most 0.2 dex; we argue that some of this scatter is due to differing degrees of tidal stripping of the globular cluster systems between central and satellite galaxies. We suggest that this correlation can be understood if most globular clusters form at very early stages in galaxy evolution, largely avoiding the feedback processes that inhibited the bulk of field-star formation in their host galaxies. The actual mean value of eta also suggests that about one-fourth of the initial gas mass present in protogalaxies collected into giant molecular clouds large enough to form massive, dense star clusters. Finally, our calibration of left angle bracketetaright angle bracket indicates that the halo masses of the Milky Way and M31 are (1.2 + or - 0.5) x 10 super(12) M sub(middot in circle) and (3.9 + or - 1.8)x 10 super(12) M sub(middot in circle), respectively.
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