68 research outputs found

    Spitzer Space Telescope Infrared Imaging and Spectroscopy of the Crab Nebula

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    We present 3.6, 4.5, 5.8, 8.0, 24, and 70 micron images of the Crab Nebula obtained with the Spitzer Space Telescope IRAC and MIPS cameras, Low- and High-resolution Spitzer IRS spectra of selected positions within the nebula, and a near-infrared ground-based image made in the light of [Fe II]1.644 micron. The 8.0 micron image, made with a bandpass that includes [Ar II]7.0 micron, resembles the general morphology of visible H-alpha and near-IR [Fe II] line emission, while the 3.6 and 4.5 micron images are dominated by continuum synchrotron emission. The 24 micron and 70 micron images show enhanced emission that may be due to line emission or the presence of a small amount of warm dust in the nebula on the order of less than 1% of a solar mass. The ratio of the 3.6 and 4.5 micron images reveals a spatial variation in the synchrotron power law index ranging from approximately 0.3 to 0.8 across the nebula. Combining this information with optical and X-ray synchrotron images, we derive a broadband spectrum that reflects the superposition of the flatter spectrum jet and torus with the steeper diffuse nebula, and suggestions of the expected pileup of relativistic electrons just before the exponential cutoff in the X-ray. The pulsar, and the associated equatorial toroid and polar jet structures seen in Chandra and HST images (Hester et al. 2002) can be identified in all of the IRAC images. We present the IR photometry of the pulsar. The forbidden lines identified in the high resolution IR spectra are all double due to Doppler shifts from the front and back of the expanding nebula and give an expansion velocity of approximately 1264 km/s.Comment: 21 pages, 4 tables, 16 figure

    N-band Imaging of Seyfert Nuclei and the MIR-X-ray correlation

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    We present new mid-infrared (N-band) images of a sample of eight nearby Seyfert galaxies. In all of our targets, we detect a central unresolved source, which in some cases has been identified for the first time. In particular, we have detected the mid-infrared emission from the active nucleus of NGC 4945, which previously remained undetected at any wavelength but hard X-rays. We also detect circumnuclear extended emission in the Circinus galaxy along its major axis, and find marginal evidence for extended circumnuclear emission in NGC 3281. The high spatial resolution (1.7") of our data allows us to separate the flux of the nuclear point sources from the extended circumnuclear starburst (if present). We complement our sample with literature data for a number of non-active starburst galaxies, and relate the nuclear N-band flux to published hard (2-10 kev) X-ray fluxes. We find tight and well-separated correlations between nuclear N-band flux and X-ray flux for both Seyfert and starburst nuclei which span over 3 orders of magnitude in luminosity. We demonstrate that these correlations can be used as a powerful classification tool for galactic nuclei. For example, we find strong evidence against NGC 1808 currently harbouring an active Seyfert nucleus based on its position in the mid-infrared-X-ray diagram. On the other hand, we confirm that NGC 4945 is in fact a Seyfert 2 galaxy.Comment: 31 pages, incl. 4 figures, uses AASTex. Replaced with accepted version after minor modifications. To appear in Ap

    Mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not (Order Scleractinia, Class Anthozoa, Phylum Cnidaria)

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    Modern hard corals (Class Hexacorallia; Order Scleractinia) are widely studied because of their fundamental role in reef building and their superb fossil record extending back to the Triassic. Nevertheless, interpretations of their evolutionary relationships have been in flux for over a decade. Recent analyses undermine the legitimacy of traditional suborders, families and genera, and suggest that a non-skeletal sister clade (Order Corallimorpharia) might be imbedded within the stony corals. However, these studies either sampled a relatively limited array of taxa or assembled trees from heterogeneous data sets. Here we provide a more comprehensive analysis of Scleractinia (127 species, 75 genera, 17 families) and various outgroups, based on two mitochondrial genes (cytochrome oxidase I, cytochrome b), with analyses of nuclear genes (ßtubulin, ribosomal DNA) of a subset of taxa to test unexpected relationships. Eleven of 16 families were found to be polyphyletic. Strikingly, over one third of all families as conventionally defined contain representatives from the highly divergent "robust" and "complex" clades. However, the recent suggestion that corallimorpharians are true corals that have lost their skeletons was not upheld. Relationships were supported not only by mitochondrial and nuclear genes, but also often by morphological characters which had been ignored or never noted previously. The concordance of molecular characters and more carefully examined morphological characters suggests a future of greater taxonomic stability, as well as the potential to trace the evolutionary history of this ecologically important group using fossils

    Accurate classification of 29 objects detected in the 39 months Palermo Swift/BAT hard X-ray catalogue

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    Through an optical campaign performed at 4 telescopes located in the northern and the southern hemispheres, plus archival data from two on-line sky surveys, we have obtained optical spectroscopy for 29 counterparts of unclassified or poorly studied hard X-ray emitting objects detected with Swift/BAT and listed in the 39 months Palermo catalogue. All these objects have also observations taken with Swift/XRT or XMM-EPIC which not only allow us to pinpoint their optical counterpart, but also to study their X-ray spectral properties (column density, power law photon index and F2-10 keV flux). We find that 28 sources in our sample are AGN; 7 are classified as type 1 while 21 are of type 2; the remaining object is a galactic cataclysmic variable. Among our type 1 AGN, we find 5 objects of intermediate Seyfert type (1.2-1.9) and one Narrow Line Seyfert 1 galaxy; for 4 out of 7 sources, we have been able to estimate the central black hole mass. Three of the type 2 AGN of our sample display optical features typical of the LINER class and one is a likely Compton thick AGN. All galaxies classified in this work are relatively nearby objects since their redshifts lie in the range 0.008-0.075; the only galactic object found lies at an estimated distance of 90 pc. We have also investigated the optical versus X-ray emission ratio of the galaxies of our sample to test the AGN unified model. For them, we have also compared the X-ray absorption (due to gas) with the optical reddening (due to dust): we find that for most of our sources, specifically those of type 1.9-2.0 the former is higher than the latter confirming early results by Maiolino et al. (2001); this is possibly due to the properties of dust in the circumnuclear obscuring torus of the AGN.Comment: 15 pages, 4 figures, 8 tables, accepted for publication on Astronomy and Astrophysic

    Low and High Ionization Absorption Properties of Mg II Absorption-Selected Galaxies at Intermediate Redshifts. I. General Properties

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    We present extensive metal-line absorption properties for 45 absorption systems that were selected by their Mg II absorption at redshifts between 0.4 and 1.4. For each system the properties of several chemical species are determined, including a wide range of ionization conditions. In the optical, the absorption systems have been observed at ~6 km/s resolution with HIRES/Keck, which covered Mg II, several Fe II transitions, Mg I, and in some cases (depending upon redshift), Ca II, Ti II, Mn II, and Al III. Ultraviolet, lower resolution (~230 km/s) Faint Object Spectrograph data (1600 - 3275 Ang) were obtained from the Hubble Space Telescope archive. These spectra covered Al II, Al III, Si II, Si III, Si IV, C II, C III, C IV, N V, O VI, and several Lyman series transitions, with coverage dependent upon the absorption system redshift. From these data, we infer that Mg II absorbing galaxies at intermediate redshifts have multiphase gaseous structures.Comment: Accepted: The Astrophysical Journa

    ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and Timing

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    We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by \asca. The imaging data reveal a number of serendipitous hard X-ray sources in some source fields, but none contribute significantly to the hard X-ray flux of the AGN. All but one of the Seyferts show evidence for variability on timescales of minutes-hours, with the amplitude anti-correlated with the source luminosity, confirming previous results. In at least 8 sources, there is evidence that the variability amplitude below 2 keV is greater than that in the hard X-ray band, perhaps indicating variable components other than the power-law in the soft band. Ultra-rapid variability, implying significant power at frequencies >103> 10^{-3}~Hz is detected in at least 5 sources, but is difficult to detect in most cases, due to the sampling and signal-to-noise ratio. In Mrk 766 and MCG-6-30-15 there is also an indication that the high--frequency power--spectra are variable in shape and/or intensity. There is similar evidence in NGC 4151, but on longer time scales.Comment: 30 pages, 5 figures. LaTeX with encapsulated postscript. To appear in the Astrophysical Journal. Also available via http://lheawww.gsfc.nasa.gov/~nandra/pubs/paper1/abstract.htm

    Expert range maps of global mammal distributions harmonised to three taxonomic authorities

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    Aim: Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW). Location: Global. Taxon: All extant mammal species. Methods: Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species). Results: Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use. Main conclusion: Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control.Fil: Marsh, Charles J.. Yale University; Estados UnidosFil: Sica, Yanina. Yale University; Estados UnidosFil: Burguin, Connor. University of New Mexico; Estados UnidosFil: Dorman, Wendy A.. University of Yale; Estados UnidosFil: Anderson, Robert C.. University of Yale; Estados UnidosFil: del Toro Mijares, Isabel. University of Yale; Estados UnidosFil: Vigneron, Jessica G.. University of Yale; Estados UnidosFil: Barve, Vijay. University Of Florida. Florida Museum Of History; Estados UnidosFil: Dombrowik, Victoria L.. University of Yale; Estados UnidosFil: Duong, Michelle. University of Yale; Estados UnidosFil: Guralnick, Robert. University Of Florida. Florida Museum Of History; Estados UnidosFil: Hart, Julie A.. University of Yale; Estados UnidosFil: Maypole, J. Krish. University of Yale; Estados UnidosFil: McCall, Kira. University of Yale; Estados UnidosFil: Ranipeta, Ajay. University of Yale; Estados UnidosFil: Schuerkmann, Anna. University of Yale; Estados UnidosFil: Torselli, Michael A.. University of Yale; Estados UnidosFil: Lacher, Thomas. Texas A&M University; Estados UnidosFil: Wilson, Don E.. National Museum of Natural History; Estados UnidosFil: Abba, Agustin Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Aguirre, Luis F.. Universidad Mayor de San Simón; BoliviaFil: Arroyo Cabrales, Joaquín. Instituto Nacional de Antropología E Historia, Mexico; MéxicoFil: Astúa, Diego. Universidade Federal de Pernambuco; BrasilFil: Baker, Andrew M.. Queensland University of Technology; Australia. Queensland Museum; AustraliaFil: Braulik, Gill. University of St. Andrews; Reino UnidoFil: Braun, Janet K.. Oklahoma State University; Estados UnidosFil: Brito, Jorge. Instituto Nacional de Biodiversidad; EcuadorFil: Busher, Peter E.. Boston University; Estados UnidosFil: Burneo, Santiago F.. Pontificia Universidad Católica del Ecuador; EcuadorFil: Camacho, M. Alejandra. Pontificia Universidad Católica del Ecuador; EcuadorFil: de Almeida Chiquito, Elisandra. Universidade Federal do Espírito Santo; BrasilFil: Cook, Joseph A.. University of New Mexico; Estados UnidosFil: Cuéllar Soto, Erika. Sultan Qaboos University; OmánFil: Davenport, Tim R. B.. Wildlife Conservation Society; TanzaniaFil: Denys, Christiane. Muséum National d'Histoire Naturelle; FranciaFil: Dickman, Christopher R.. The University Of Sydney; AustraliaFil: Eldridge, Mark D. B.. Australian Museum; AustraliaFil: Fernandez Duque, Eduardo. University of Yale; Estados UnidosFil: Francis, Charles M.. Environment And Climate Change Canada; CanadáFil: Frankham, Greta. Australian Museum; AustraliaFil: Freitas, Thales. Universidade Federal do Rio Grande do Sul; BrasilFil: Friend, J. Anthony. Conservation And Attractions; AustraliaFil: Giannini, Norberto Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Gursky-Doyen, Sharon. Texas A&M University; Estados UnidosFil: Hackländer, Klaus. Universitat Fur Bodenkultur Wien; AustriaFil: Hawkins, Melissa. National Museum of Natural History; Estados UnidosFil: Helgen, Kristofer M.. Australian Museum; AustraliaFil: Heritage, Steven. University of Duke; Estados UnidosFil: Hinckley, Arlo. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Holden, Mary. American Museum of Natural History; Estados UnidosFil: Holekamp, Kay E.. Michigan State University; Estados UnidosFil: Humle, Tatyana. University Of Kent; Reino UnidoFil: Ibáñez Ulargui, Carlos. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Jackson, Stephen M.. Australian Museum; AustraliaFil: Janecka, Mary. University of Pittsburgh at Johnstown; Estados Unidos. University of Pittsburgh; Estados UnidosFil: Jenkins, Paula. Natural History Museum; Reino UnidoFil: Juste, Javier. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Leite, Yuri L. R.. Universidade Federal do Espírito Santo; BrasilFil: Novaes, Roberto Leonan M.. Universidade Federal do Rio de Janeiro; BrasilFil: Lim, Burton K.. Royal Ontario Museum; CanadáFil: Maisels, Fiona G.. Wildlife Conservation Society; Estados UnidosFil: Mares, Michael A.. Oklahoma State University; Estados UnidosFil: Marsh, Helene. James Cook University; AustraliaFil: Mattioli, Stefano. Università degli Studi di Siena; ItaliaFil: Morton, F. Blake. University of Hull; Reino UnidoFil: Ojeda, Agustina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Ordóñez Garza, Nicté. Instituto Nacional de Biodiversidad; EcuadorFil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Pavan, Mariana. Universidade de Sao Paulo; BrasilFil: Riley, Erin P.. San Diego State University; Estados UnidosFil: Rubenstein, Daniel I.. University of Princeton; Estados UnidosFil: Ruelas, Dennisse. Museo de Historia Natural, Lima; PerúFil: Schai-Braun, Stéphanie. Universitat Fur Bodenkultur Wien; AustriaFil: Schank, Cody J.. University of Texas at Austin; Estados UnidosFil: Shenbrot, Georgy. Ben Gurion University of the Negev; IsraelFil: Solari, Sergio. Universidad de Antioquia; ColombiaFil: Superina, Mariella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Tsang, Susan. American Museum of Natural History; Estados UnidosFil: Van Cakenberghe, Victor. Universiteit Antwerp; BélgicaFil: Veron, Geraldine. Université Pierre et Marie Curie; FranciaFil: Wallis, Janette. Kasokwa-kityedo Forest Project; UgandaFil: Whittaker, Danielle. Michigan State University; Estados UnidosFil: Wells, Rod. Flinders University.; AustraliaFil: Wittemyer, George. State University of Colorado - Fort Collins; Estados UnidosFil: Woinarski, John. Charles Darwin University; AustraliaFil: Upham, Nathan S.. University of Yale; Estados UnidosFil: Jetz, Walter. University of Yale; Estados Unido

    Expert range maps of global mammal distributions harmonised to three taxonomic authorities

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    AimComprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW).LocationGlobal.TaxonAll extant mammal species.MethodsRange maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species).ResultsRange maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use.Main conclusionExpert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control
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