IMPORTANCE: The use of genome-wide tests to provide molecular diagnosis for individuals with autism spectrum disorder (ASD) requires more study. OBJECTIVE: To perform chromosomal microarray analysis ...(CMA) and whole-exome sequencing (WES) in a heterogeneous group of children with ASD to determine the molecular diagnostic yield of these tests in a sample typical of a developmental pediatric clinic. DESIGN, SETTING, AND PARTICIPANTS: The sample consisted of 258 consecutively ascertained unrelated children with ASD who underwent detailed assessments to define morphology scores based on the presence of major congenital abnormalities and minor physical anomalies. The children were recruited between 2008 and 2013 in Newfoundland and Labrador, Canada. The probands were stratified into 3 groups of increasing morphological severity: essential, equivocal, and complex (scores of 0-3, 4-5, and ≥6). EXPOSURES: All probands underwent CMA, with WES performed for 95 proband-parent trios. MAIN OUTCOMES AND MEASURES: The overall molecular diagnostic yield for CMA and WES in a population-based ASD sample stratified in 3 phenotypic groups. RESULTS: Of 258 probands, 24 (9.3%, 95% CI, 6.1%-13.5%) received a molecular diagnosis from CMA and 8 of 95 (8.4%, 95% CI, 3.7%-15.9%) from WES. The yields were statistically different between the morphological groups. For CMA, the proportion of children with a positive test result was 7 of 168 (4.2%, 95% CI, 1.7%-8.4%) in the essential group, 4 of 37 (10.8%, 95% CI, 3.0%-25.4%) in the equivocal group, and 13 of 53 (24.5%, 95% CI, 13.8%-38.3%) in the complex group (P < .001). For WES, the proportions were 2 of 64 (3.1%, 95% CI, 0.0%-10.8%), 2 of 7 (28.6%, 95% CI, 3.7%-71.0%), and 4 of 24 (16.7%, 95% CI, 4.7%-37.4%), respectively (3-group comparison, P = .02). Among the children who underwent both CMA and WES testing, the estimated proportion with an identifiable genetic etiology was 15.8% (95% CI, 9.1%-24.7%; 15/95 children). This included 2 children who received molecular diagnoses from both tests. The combined molecular diagnostic yield was 6.3% (95% CI, 1.7%-15.2%) in the essential group (4/64 children), 28.6% (95% CI, 3.7%-71.0%) in the equivocal group (2/7 children), and 37.5% (95% CI, 18.8%-59.4%) in the complex group (9/24 children; 3-group comparison, P = .001). The combined yield was significantly higher in the complex group when compared with the essential group (pairwise comparison, P = .002). CONCLUSIONS AND RELEVANCE: Among a heterogeneous sample of children with ASD, the molecular diagnostic yields of CMA and WES were comparable, and the combined molecular diagnostic yield was higher in children with more complex morphological phenotypes in comparison with the children in the essential category. If replicated in additional populations, these findings may inform appropriate selection of molecular diagnostic testing for children affected by ASD.
The Galaxy End Sequence Eales, Stephen; deVis, Pieter; Smith, Matthew WL ...
Monthly Notices of the Royal Astronomical Society,
03/2017, Letnik:
465, Številka:
3
Journal Article
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A common assumption is that galaxies fall in two distinct regions of a plot of specific star formation rate (SSFR) versus galaxy stellar mass: a star-forming galaxy main sequence (GMS) and a separate ...region of 'passive' or 'red and dead galaxies'. Starting from a volume-limited sample of nearby galaxies designed to contain most of the stellar mass in this volume, and thus representing the end-point of ...12 billion years of galaxy evolution, we investigate the distribution of galaxies in this diagram today. We show that galaxies follow a strongly curved extended GMS with a steep negative slope at high galaxy stellar masses. There is a gradual change in the morphologies of the galaxies along this distribution, but there is no clear break between early-type and late-type galaxies. Examining the other evidence that there are two distinct populations, we argue that the 'red sequence' is the result of the colours of galaxies changing very little below a critical value of the SSFR, rather than implying a distinct population of galaxies. Herschel observations, which show at least half of early-type galaxies contain a cool interstellar medium, also imply continuity between early-type and late-type galaxies. This picture of a unitary population of galaxies requires more gradual evolutionary processes than the rapid quenching process needed to explain two distinct populations. We challenge theorists to predict quantitatively the properties of this 'Galaxy End Sequence'. (ProQuest: ... denotes formulae/symbols omitted.)
In this work we present IRAM 30-m telescope observations of a sample of bulge-dominated galaxies with large dust lanes, which have had a recent minor merger. We find these galaxies are very gas rich, ...with H2 masses between 4 × 108 and 2 × 1010 M⊙. We use these molecular gas masses, combined with atomic gas masses from an accompanying paper, to calculate gas-to-dust and gas-to-stellar-mass ratios. The gas-to-dust ratios of our sample objects vary widely (between ≈50 and 750), suggesting many objects have low gas-phase metallicities, and thus that the gas has been accreted through a recent merger with a lower mass companion. We calculate the implied minor companion masses and gas fractions, finding a median predicted stellar mass ratio of ≈40:1. The minor companion likely had masses between ≈107 and 1010 M⊙. The implied merger mass ratios are consistent with the expectation for low-redshift gas-rich mergers from simulations. We then go on to present evidence that (no matter which star formation rate indicator is used) our sample objects have very low star formation efficiencies (star formation rate per unit gas mass), lower even than the early-type galaxies from ATLAS3D which already show a suppression. This suggests that minor mergers can actually suppress star formation activity. We discuss mechanisms that could cause such a suppression, include dynamical effects induced by the minor merger.
Abstract
The Herschel Space Observatory has revealed a very different galaxyscape from that shown by optical surveys which presents a challenge for galaxy-evolution models. The Herschel surveys ...reveal (1) that there was rapid galaxy evolution in the very recent past and (2) that galaxies lie on a single Galaxy Sequence (GS) rather than a star-forming ‘main sequence’ and a separate region of ‘passive’ or ‘red-and-dead’ galaxies. The form of the GS is now clearer because far-infrared surveys such as the Herschel ATLAS pick up a population of optically red star-forming galaxies that would have been classified as passive using most optical criteria. The space-density of this population is at least as high as the traditional star-forming population. By stacking spectra of H-ATLAS galaxies over the redshift range 0.001 < z < 0.4, we show that the galaxies responsible for the rapid low-redshift evolution have high stellar masses, high star-formation rates but, even several billion years in the past, old stellar populations – they are thus likely to be relatively recent ancestors of early-type galaxies in the Universe today. The form of the GS is inconsistent with rapid quenching models and neither the analytic bathtub model nor the hydrodynamical EAGLE simulation can reproduce the rapid cosmic evolution. We propose a new gentler model of galaxy evolution that can explain the new Herschel results and other key properties of the galaxy population.
We present the largest submillimeter images that have been made of the extragalactic sky. The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 660 deg2 with the PACS and ...SPIRE cameras in five photometric bands: 100, 160, 250, 350, and 500 m. In this paper we present the images from our two largest fields, which account for ∼75% of the survey. The first field is 180.1 deg2 in size, centered on the north Galactic pole (NGP), and the second is 317.6 deg2 in size, centered on the south Galactic pole. The NGP field serendipitously contains the Coma cluster. Over most (∼80%) of the images, the pixel noise, including both instrumental noise and confusion noise, is approximately 3.6, and 3.5 mJy pix−1 at 100 and 160 m, and 11.0, 11.1 and 12.3 mJy beam−1 at 250, 350 and 500 m, respectively, but reaches lower values in some parts of the images. If a matched filter is applied to optimize point-source detection, our total 1 map sensitivity is 5.7, 6.0, and 7.3 mJy at 250, 350, and 500 m, respectively. We describe the results of an investigation of the noise properties of the images. We make the most precise estimate of confusion in SPIRE maps to date, finding values of 3.12 0.07, 4.13 0.02, and 4.45 0.04 mJy beam−1 at 250, 350, and 500 m in our un-convolved maps. For PACS we find an estimate of the confusion noise in our fast-parallel observations of 4.23 and 4.62 mJy beam−1 at 100 and 160 m. Finally, we give recipes for using these images to carry out photometry, both for unresolved and extended sources.
Aims. We analyze the applicability of far-infrared fine-structure lines Cii 158 μm, Oi 63 μm, and Oiii 88 μm to reliably trace the star formation rate (SFR) in a sample of low-metallicity dwarf ...galaxies from the Herschel Dwarf Galaxy Survey and, furthermore, extend the analysis to a broad sample of galaxies of various types and metallicities in the literature. Methods. We study the trends and scatter in the relation between the SFR (as traced by GALEX FUV and MIPS 24 μm) and far-infrared line emission, on spatially resolved and global galaxy scales, in dwarf galaxies. We assemble far-infrared line measurements from the literature and infer whether the far-infrared lines can probe the SFR (as traced by the total infrared luminosity) in a variety of galaxy populations. Results. In metal-poor dwarfs, the Oi63 and Oiii88 lines show the strongest correlation with the SFR with an uncertainty on the SFR estimates better than a factor of 2, while the link between Cii emission and the SFR is more dispersed (uncertainty factor of 2.6). The increased scatter in the SFR–LCII relation toward low metal abundances, warm dust temperatures, and large filling factors of diffuse, highly ionized gas suggests that other cooling lines start to dominate depending on the density and ionization state of the gas. For the literature sample, we evaluate the correlations for a number of different galaxy populations. The Cii and Oi63 lines are considered to be reliable SFR tracers in starburst galaxies, recovering the star formation activity within an uncertainty of factor 2. For sources with composite and active galactic nucleus (AGN) classifications, all three FIR lines can recover the SFR with an uncertainty factor of 2.3. The SFR calibrations for ultra-luminous infrared galaxies (ULIRGs) are similar to starbursts/AGNs in terms of scatter but offset from the starburst/AGN SFR relations because of line deficits relative to their total infrared luminosity. While the number of detections of the FIR fine-structure lines is still very limited at high redshift for Oi63 and Oiii88, we provide an SFR calibration for Cii.
ABSTRACT
We observed the starburst galaxy M82 in 850 µm polarized light with the POL-2 polarimeter on the James Clerk Maxwell Telescope (JCMT). We interpret our observed polarization geometry as ...tracing a two-component magnetic field: a poloidal component aligned with the galactic ‘superwind’, extending to a height ∼350 pc above and below the central bar; and a spiral-arm-aligned, or possibly toroidal, component in the plane of the galaxy, which dominates the 850 µm polarized light distribution at galactocentric radii ≳2 kpc. Comparison of our results with recent High-resolution Airborne Wideband Camera Plus (HAWC+) measurements of the field in the dust entrained by the M82 superwind suggests that the superwind breaks out from the central starburst at ∼350 pc above the plane of the galaxy.
Far-reaching dust distribution in galaxy discs Smith, Matthew W. L; Eales, Stephen A; De Looze, Ilse ...
Monthly Notices of the Royal Astronomical Society,
10/2016, Letnik:
462, Številka:
1
Journal Article
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In most studies of dust in galaxies, dust is only detected from its emission to approximately the optical radius of the galaxy. By combining the signal of 110 spiral galaxies observed as part of the ...Herschel Reference Survey, we are able to improve our sensitivity by an order of magnitude over that for a single object. Here we report the direct detection of dust from its emission that extends out to at least twice the optical radius. We find that the distribution of dust is consistent with an exponential at all radii with a gradient of ∼−1.7 dex
$R_{25}^{-1}$
. Our dust temperature declines linearly from ∼25 K in the centre to 15 K at R
25 from where it remains constant out to ∼2.0 R
25. The surface density of dust declines with radius at a similar rate to the surface density of stars but more slowly than the surface density of the star-formation rate. Studies based on dust extinction and reddening of high-redshift quasars have concluded that there are substantial amounts of dust in intergalactic space. By combining our results with the number counts and angular correlation function from the SDSS, we show that with Milky Way-type dust we can explain the reddening of the quasars by the dust within galactic discs alone. Given the uncertainties in the properties of any intergalactic dust, we cannot rule out its existence, but our results show that statistical investigations of the dust in galactic haloes that use the reddening of high-redshift objects must take account of the dust in galactic discs.
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