32 research outputs found

    Stellar Half-Mass Radii of 0.5<z<2.30.5<z<2.3 Galaxies: Comparison with JWST/NIRCam Half-Light Radii

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    We use CEERS JWST/NIRCam imaging to measure rest-frame near-IR light profiles of >>500 M>1010 MM_\star>10^{10}~M_\odot galaxies in the redshift range 0.5<z<2.30.5<z<2.3. We compare the resulting rest-frame 1.5-2μ\mum half-light radii (RNIRR_{\rm{NIR}}) with stellar half-mass radii (\rmass) derived with multi-color light profiles from CANDELS HST imaging. In general agreement with previous work, we find that RNIRR_{\rm{NIR}} and \rmass~are up to 40\%~smaller than the rest-frame optical half-light radius RoptR_{\rm{opt}}. The agreement between RNIRR_{\rm{NIR}} and \rmass~is excellent, with negligible systematic offset (<<0.03 dex) up to z=2z=2 for quiescent galaxies and up to z=1.5z=1.5 for star-forming galaxies. We also deproject the profiles to estimate \rmassd, the radius of a sphere containing 50\% of the stellar mass. We present the RMR-M_\star distribution of galaxies at 0.5<z<1.50.5<z<1.5, comparing RoptR_{\rm{opt}}, \rmass~and \rmassd. The slope is significantly flatter for \rmass~and \rmassd~ compared to RoptR_{\rm{opt}}, mostly due to downward shifts in size for massive star-forming galaxies, while \rmass~and \rmassd~do not show markedly different trends. Finally, we show rapid size evolution (R(1+z)1.7±0.1R\propto (1+z)^{-1.7\pm0.1}) for massive (M>1011 MM_\star>10^{11}~M_\odot) quiescent galaxies between z=0.5z=0.5 and z=2.3z=2.3, again comparing RoptR_{\rm{opt}}, \rmass~and \rmassd. We conclude that the main tenets of the size evolution narrative established over the past 20 years, based on rest-frame optical light profile analysis, still hold in the era of JWST/NIRCam observations in the rest-frame near-IR.Comment: Submitted to ApJ. Comments welcom

    A panchromatic study of BLAST counterparts: total star-formation rate, morphology, AGN fraction and stellar mass

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    We carry out a multi-wavelength study of individual galaxies detected by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) and identified at other wavelengths, using data spanning the radio to the ultraviolet (UV). We develop a Monte Carlo method to account for flux boosting, source blending, and correlations among bands, which we use to derive deboosted far-infrared (FIR) luminosities for our sample. We estimate total star-formation rates for BLAST counterparts with z < 0.9 by combining their FIR and UV luminosities. Star formation is heavily obscured at L_FIR > 10^11 L_sun, z > 0.5, but the contribution from unobscured starlight cannot be neglected at L_FIR < 10^11 L_sun, z < 0.25. We assess that about 20% of the galaxies in our sample show indication of a type-1 active galactic nucleus (AGN), but their submillimeter emission is mainly due to star formation in the host galaxy. We compute stellar masses for a subset of 92 BLAST counterparts; these are relatively massive objects, with a median mass of ~10^11 M_sun, which seem to link the 24um and SCUBA populations, in terms of both stellar mass and star-formation activity. The bulk of the BLAST counterparts at z<1 appear to be run-of-the-mill star-forming galaxies, typically spiral in shape, with intermediate stellar masses and practically constant specific star-formation rates. On the other hand, the high-z tail of the BLAST counterparts significantly overlaps with the SCUBA population, in terms of both star-formation rates and stellar masses, with observed trends of specific star-formation rate that support strong evolution and downsizing.Comment: Accepted for publication in the Astrophysical Journal. 44 pages, 11 figures. The SED template for the derivation of L_FIR has changed (added new figure) and the discussion on the stellar masses has been improved. The complete set of full-color postage-stamps can be found at http://blastexperiment.info/results_images/moncelsi

    Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science

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    SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry out the first all-sky spectral survey and provide for every 6.2" pixel a spectra between 0.75 and 4.18 μ\mum [with R\sim41.4] and 4.18 and 5.00 μ\mum [with R\sim135]. The SPHEREx team has proposed three specific science investigations to be carried out with this unique data set: cosmic inflation, interstellar and circumstellar ices, and the extra-galactic background light. It is readily apparent, however, that many other questions in astrophysics and planetary sciences could be addressed with the SPHEREx data. The SPHEREx team convened a community workshop in February 2016, with the intent of enlisting the aid of a larger group of scientists in defining these questions. This paper summarizes the rich and varied menu of investigations that was laid out. It includes studies of the composition of main belt and Trojan/Greek asteroids; mapping the zodiacal light with unprecedented spatial and spectral resolution; identifying and studying very low-metallicity stars; improving stellar parameters in order to better characterize transiting exoplanets; studying aliphatic and aromatic carbon-bearing molecules in the interstellar medium; mapping star formation rates in nearby galaxies; determining the redshift of clusters of galaxies; identifying high redshift quasars over the full sky; and providing a NIR spectrum for most eROSITA X-ray sources. All of these investigations, and others not listed here, can be carried out with the nominal all-sky spectra to be produced by SPHEREx. In addition, the workshop defined enhanced data products and user tools which would facilitate some of these scientific studies. Finally, the workshop noted the high degrees of synergy between SPHEREx and a number of other current or forthcoming programs, including JWST, WFIRST, Euclid, GAIA, K2/Kepler, TESS, eROSITA and LSST.Comment: Report of the First SPHEREx Community Workshop, http://spherex.caltech.edu/Workshop.html , 84 pages, 28 figure

    International Perspectives on the Legal Environment for Selection

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    Perspectives from 22 countries on aspects of the legal environment for selection are presented in this article. Issues addressed include (a) whether there are racial/ethnic/religious subgroups viewed as "disadvantaged,” (b) whether research documents mean differences between groups on individual difference measures relevant to job performance, (c) whether there are laws prohibiting discrimination against specific groups, (d) the evidence required to make and refute a claim of discrimination, (e) the consequences of violation of the laws, (f) whether particular selection methods are limited or banned, (g) whether preferential treatment of members of disadvantaged groups is permitted, and (h) whether the practice of industrial and organizational psychology has been affected by the legal environmen

    Properties of submillimeter galaxies in the CANDELS GOODS-south field

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    We derive physical properties of 10 submillimeter galaxies located in the CANDELS coverage of the GOODS-S field. The galaxies were first identified as submillimeter sources with the LABOCA bolometer and subsequently targeted for 870 m continuum observation with ALMA. The high angular resolution of the ALMA imaging allows secure counterparts to be identified in the CANDELS multiband data set. The CANDELS data provide deep photometric data from UV through near-infrared wavelengths. Using synthetic spectral energy distributions, we derive photometric redshifts, stellar masses, extinction, ages, and the star formation history. The redshift range is z = 1.65-4.76, with two of the galaxies located at z > 4. Two submillimeter galaxy (SMG) counterparts have stellar masses 2-3 orders of magnitude lower than the rest. The remaining SMG counterparts have stellar masses around 1 x 1011 M. The stellar population in the SMGs is typically older than the expected duration of the submillimeter phase, suggesting that the star formation history of SMGs is more complex than a single burst. Non-parametric morphology indices suggest that the SMG counterparts are among the most asymmetric systems compared with galaxies of the same stellar mass and redshift. The Hubble Space Telescope images show that three of the SMGs are associated with ongoing mergers. The remaining counterparts are isolated. Estimating the dust and molecular gas mass from the submillimeter fluxes, and comparing with our stellar masses shows that the gas mass fraction of SMGs is ~28% and that the final stellar mass is likely to be ~(1 - 2) x 1011 M.IS

    Next-generation sequencing-based genome diagnostics across clinical genetics centers: Implementation choices and their effects

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    Implementation of next-generation DNA sequencing (NGS) technology into routine diagnostic genome care requires strategic choices. Instead of theoretical discussions on the consequences of such choices, we compared NGS-based diagnostic practices in eight clinical genetic centers in the Netherlands, based on genetic testing of nine pre-selected patients with cardiomyopathy. We highlight critical implementation choices, including the specific contributions of laboratory and medical specialists, bioinformaticians and researchers to diagnostic genome care, and how these affect interpretation and reporting of variants. Reported pathogenic mutations were consistent for all but one patient. Of the two centers that were inconsistent in their diagnosis, one reported to have found 'no causal variant', thereby underdiagnosing this patient. The other provided an alternative diagnosis, identifying another variant as causal than the other centers. Ethical and legal analysis showed that informed consent procedures in all centers were generally adequate for diagnostic NGS applications that target a limited set of genes, but not for exome- and genome-based diagnosis. We propose changes to further improve and align these procedures, taking into account the blurring boundary between diagnostics and research, and specific counseling options for exome- and genome-based diagnostics. We conclude that alternative diagnoses may infer a certain level of 'greediness' to come to a positive diagnosis in interpreting sequencing results. Moreover, there is an increasing interdependence of clinic, diagnostics and research departments for comprehensive diagnostic genome care. Therefore, we invite clinical geneticists, physicians, researchers, bioinformatics experts and patients to reconsider their role and position in future diagnostic genome care

    Effect of iron-sulfur cluster assembly proteins on the expression of Escherichia coli lipoic acid synthase

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    Lipoic Acid Synthase (LipA) can accommodate a [4Fe-4S] cluster that is thought to be essential for the insertion of sulfur into an octanoyl substrate during the biosynthesis of lipoic acid. With the objective of improving soluble holo-LipA expression, a series of multi-cistronic plasmids were constructed carrying lipA in combination with one of the three systems: groE/SL, trxA, or the isc operon. Co-expression of lipA with the isc operon approximately trebled the isolated yield of soluble LipA and resulted in efficient assembly of the Fe-S cluster. This strategy may be helpful in the soluble expression of a wide range of Fe-S cluster-dependent proteins
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