12 research outputs found

    The Outstanding Decisions of the United States Supreme Court in 1954

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    We perform a kinematic and morphological analysis of 44 star-forming galaxies at z ̃ 2 in the COSMOS legacy field using near-infrared spectroscopy from Keck/MOSFIRE and F160W imaging from CANDELS/3D-HST as part of the ZFIRE survey. Our sample consists of cluster and field galaxies from 2.0 < z < 2.5 with K-band multi-object slit spectroscopic measurements of their Hα emission lines. Hα rotational velocities and gas velocity dispersions are measured using the Heidelberg Emission Line Algorithm (HELA), which compares directly to simulated 3D data cubes. Using a suite of simulated emission lines, we determine that HELA reliably recovers input S 0.5 and angular momentum at small offsets, but V 2.2/σ g values are offset and highly scattered. We examine the role of regular and irregular morphology in the stellar mass kinematic scaling relations, deriving the kinematic measurement S 0.5, and finding {log}({S}0.5)=(0.38+/- 0.07){log}(M/{M}☉ -10)+(2.04+/- 0.03) with no significant offset between morphological populations and similar levels of scatter (̃0.16 dex). Additionally, we identify a correlation between M ⋆ and V 2.2/σ g for the total sample, showing an increasing level of rotation dominance with increasing M ⋆, and a high level of scatter for both regular and irregular galaxies. We estimate the specific angular momenta (j disk) of these galaxies and find a slope of 0.36 ± 0.12, shallower than predicted without mass-dependent disk growth, but this result is possibly due to measurement uncertainty at M ⋆ < 9.5 However, through a Kolmogorov-Smirnov test we find irregular galaxies to have marginally higher j disk values than regular galaxies, and high scatter at low masses in both populations

    MOSEL: Strong [OIII]5007 \AA\ Emitting Galaxies at (3<z<4) from the ZFOURGE Survey

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    To understand how strong emission line galaxies (ELGs) contribute to the overall growth of galaxies and star formation history of the universe, we target Strong ELGs (SELGs) from the ZFOURGE imaging survey that have blended (Hb+[OIII]) rest-frame equivalent widths of >230A and 2.5<zphot<4.0. Using Keck/MOSFIRE, we measure 49 redshifts for galaxies brighter than Ks=25 mag as part of our Multi-Object Spectroscopic Emission Line (MOSEL) survey. Our spectroscopic success rate is ~53% and zphot uncertainty is sigma_z= [Delta(z)/(1+z)]=0.0135. We confirm 31 ELGs at 3<zspec<3.8 and show that Strong ELGs have spectroscopic rest-frame [OIII]5007A equivalent widths of 100-500A and tend to be lower mass systems [log(Mstar/Msun)~8.2-9.6] compared to more typical star-forming galaxies. The Strong ELGs lie ~0.9 dex above the star-forming main-sequence at z~3.5 and have high inferred gas fractions of fgas~>60%, i.e. the inferred gas masses can easily fuel a starburst to double stellar masses within ~10-100 Myr. Combined with recent results using ZFOURGE, our analysis indicates that 1) strong [OIII]5007A emission signals an early episode of intense stellar growth in low mass (Mstar<0.1M*) galaxies and 2) many, if not most, galaxies at z>3 go through this starburst phase. If true, low-mass galaxies with strong [OIII]5007A emission (EW_rest>200A) may be an increasingly important source of ionizing UV radiation at z>3.Comment: Astrophysical Journal, in pres

    Ευρετικές προσεγγίσεις του μοναδιάστατου προβλήματος πακετοποίησης

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    Article 59.1, of the International Code of Nomenclature for Algae, Fungi, and Plants (ICN; Melbourne Code), which addresses the nomenclature of pleomorphic fungi, became effective from 30 July 2011. Since that date, each fungal species can have one nomenclaturally correct name in a particular classification. All other previously used names for this species will be considered as synonyms. The older generic epithet takes priority over the younger name. Any widely used younger names proposed for use, must comply with Art. 57.2 and their usage should be approved by the Nomenclature Committee for Fungi (NCF). In this paper, we list all genera currently accepted by us in Dothideomycetes (belonging to 23 orders and 110 families), including pleomorphic and non-pleomorphic genera. In the case of pleomorphic genera, we follow the rulings of the current ICN and propose single generic names for future usage. The taxonomic placements of 1261 genera are listed as an outline. Protected names and suppressed names for 34 pleomorphic genera are listed separately. Notes and justifications are provided for possible proposed names after the list of genera. Notes are also provided on recent advances in our understanding of asexual and sexual morph linkages in Dothideomycetes. A phylogenetic tree based on four gene analyses supported 23 orders and 75 families, while 35 families still lack molecular data

    A Tale of Two Clusters: An Analysis of Gas-phase Metallicity and Nebular Gas Conditions in Proto-cluster Galaxies at z ∼ 2

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    The ZFIRE survey has spectroscopically confirmed two proto-clusters using the MOSFIRE instrument on Keck I: One at z = 2.095 in COSMOS and another at z = 1.62 in UKIRT Infrared Deep Sky Survey (UDS). Here, we use an updated ZFIRE data set to derive the properties of ionized gas regions of proto-cluster galaxies by extracting fluxes from emission lines Hβ 4861 Å, [O iii] 5007 Å, Hα 6563 Å, [N ii] 6585 Å, and [S ii] 6716,6731 Å. We measure gas-phase metallicity of members in both proto-clusters using two indicators, including a strong-line indicator relatively independent of the ionization parameter and electron density. Proto-cluster and field galaxies in both UDS and COSMOS lie on the same Mass-Metallicity Relation with both metallicity indicators. We compare our results to recent IllustrisTNG results, which report no significant gas-phase metallicity offset between proto-cluster and field galaxies until z = 1.5. This is in agreement with our observed metallicities, where no offset is measured between proto-cluster and field populations. We measure tentative evidence from stacked spectra that indicate UDS high-mass proto-cluster and field galaxies have differing [O iii]/Hβ ratios; however, these results are dependent on the sample size of the high-mass stacks

    A giant galaxy in the young Universe with a massive ring

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    In the local (redshift z ≈ 0) Universe, collisional ring galaxies make up only ~0.01% of galaxies1 and are formed by head-on galactic collisions that trigger radially propagating density waves2–4. These striking systems provide key snapshots for dissecting galactic disks and are studied extensively in the local Universe5–9. However, not much is known about distant (z > 0.1) collisional rings10–14. Here we present a detailed study of a ring galaxy at a look-back time of 10.8 Gyr (z = 2.19). Compared with our Milky Way, this galaxy has a similar stellar mass, but has a stellar half-light radius that is 1.5–2.2 times larger and is forming stars 50 times faster. The extended, diffuse stellar light outside the star-forming ring, combined with a radial velocity on the ring and an intruder galaxy nearby, provides evidence for this galaxy hosting a collisional ring. If the ring is secularly evolved15,16, the implied large bar in a giant disk would be inconsistent with the current understanding of the earliest formation of barred spirals17–21. Contrary to previous predictions10–12, this work suggests that massive collisional rings were as rare 11 Gyr ago as they are today. Our discovery offers a unique pathway for studying density waves in young galaxies, as well as constraining the cosmic evolution of spiral disks and galaxy groups

    Introduction

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