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Massive stars formed in atomic hydrogen reservoirs: H I observations of gamma-ray burst host galaxies
Get PDFLong gamma-ray bursts (GRBs), among the most energetic events in the Universe, are explosions of massive and short-lived stars, so they pinpoint locations of recent star formation. However, several GRB host galaxies have recently been found to be deficient in molecular gas (H2), believed to be the fuel of star formation. Moreover, optical spectroscopy of GRB afterglows implies that the molecular phase constitutes only a small fraction of the gas along the GRB line of sight. Here we report the first ever 21 cm line observations of GRB host galaxies, using the AustraliaTelescope Compact Array, implying high levels of atomic hydrogen (H i), which suggests that the connection between atomic gas and star formation is stronger than previously thought. In this case, it is possible that star formation is directly fuelled by atomic gas (or that the H i-to-H2 conversion is very efficient, which rapidly exhaust molecular gas), as has been theoretically shown to be possible. This can happen in low-metallicity gas near the onset of star formation because cooling of gas (necessary for star formation) is faster than the H i-to-H2 conversion. Indeed, large atomic gas reservoirs, together with low molecular gas masses, stellar, and dust masses are consistent with GRB hosts being preferentially galaxies which have very recently started a star formation episode after accreting metal-poor gas from the intergalactic medium. This provides a natural route for forming GRBs in low-metallicity environments. The gas inflow scenario is also consistent with the existence of the companion H I object with no optical counterpart ∼19 kpc from the GRB 060505 host, and with the fact that the H I centroids of the GRB 980425 and 060505 hosts do not coincide with optical centres of these galaxies, but are located close to the GRB positions. © ESO, 2015.We thank Joanna Baradziej, Stefano Covino, Paweł Michałowski, Tadeusz Michałowski, and our referee for help with improving this paper; Robert Braun, Sarah Maddison, Anita Titmarsh, Catarina Ubach, and Ivy Wong for help with the ATCA observations; Christina Thöne for analysing for us her IFU data for the GRB 060505 host; Marianne Doyle-Pegg for providing her data; Claudia Lagos for providing the predictions from her model. M.J.M. acknowledges the support of the UK Science and Technology Facilities Council, British Council Researcher Links Travel Grant, and the hospitality at the Instituto Nacional de Astrofísica, Óptica y Electrónica. The Dark Cosmology Centre is funded by the Danish National Research Foundation. L.K.H. is supported by the INAF PRIN 2012 grant. S.K. and A.N.G. acknowledge support by grant DFG Kl 766/16-1. T.M. and D.B. acknowledge the support of the Australian Research Council through grant DP110102034. A.d.U.P. acknowledges support from the European Commission (FP7-PEOPLE-2012-CIG 322307) and from the Spanish project AYA2012-39362-C02-02. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. Galaxy Evolution Explorer (GALEX) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology. This research has made use of data from HRS project. HRS is a Herschel Key Programme utilising Guaranteed Time from the SPIRE instrument team, ESAC scientists and a mission scientist. The HRS data was accessed through the Herschel Database in Marseille (HeDaM; http://hedam.lam.fr) operated by CeSAM and hosted by the Laboratoire d’Astrophysique de Marseille. This research has made use of the GHostS database (http://www.grbhosts.org), which is partly funded by Spitzer/NASA grant RSA Agreement No. 1287913; the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration; SAOImage DS9, developed by Smithsonian Astrophysical Observatory (Joye & Mandel 2003); the NASA’s Astrophysics Data System Bibliographic Services; and the Edward Wright Cosmology Calculator www.astro.ucla.edu/~wright/CosmoCalc.html (Wright 2006)
Deciphering the Holocene magmatic plumbing system dynamics beneath El Hierro (Canary Islands)
No full textOcean Island Basalts (OIBs) provide a unique window into the deep Earth dynamics that govern
the formation of volcanic islands. A comprehensive understanding of OIB systems often requires
multidisciplinary approaches, providing insights into which processes operate from source to
surface along complex pathways of magma transport and storage. Investigating these processes
during the Holocene allows for the characterisation of magmatic architectures and eruptive
dynamics over a period suf¿¿ciently prolonged and yet close to the present day, making it
representative of the current and future behaviour of volcanic areas. The Canary Archipelago
(NW African coast) represents an exceptional natural laboratory for these purposes. Here, we
provide an integrated approach to the dynamics of the magmatic plumbing system beneath El
Hierro, which is the westernmost and youngest island of the Canaries. Through the investigation
of 59 Holocene subaerial eruptions, we provide a detailed petrological and geochemical
characterisation of volcanic products ranging from felsic pyroclasts to ankaramitic lavas with
crystal contents up to 51%. Results are integrated within fractional crystallisation modelling and
mass balance calculations, revealing different degrees of crystal accumulation and melt
extraction on magmas with MgO contents above 10 wt%. These results are combined with
recently updated geological mapping, as well as with new geochronological data supported by
stratigraphic and geomorphological constraints. This holistic approach allows us to illustrate the
spatial and temporal distributions of the subaerial volcanism at El Hierro, as well as their
implications for magmatic evolution and plumbing architecture. Our ¿¿ndings shed light on the
complex magmatic processes that have governed the evolution of El Hierro¿s volcanic system
during the Holocene, with broader implications for the study of OIB magmatism in similar
settings worldwide
Photoreduction of mercuric bromides in polar ice
Get PDF10 pages, 6 figuresIn the polar regions, which are vulnerable receptors of mercury pollution, atmospheric mercury depletion events (AMDEs) efficiently convert elemental mercury (Hg(0)) into oxidized mercury (Hg(II)) via bromine oxidation. Hg(II) subsequently deposits onto snow and sea ice. While field observations have shown that a large percentage of deposited mercury is re-emitted from the ice to the atmosphere by a photoinduced process, the fundamental photochemistry that drives the re-emission process remains unknown. Here, using multiconfigurational quantum chemistry, we find that the photoreduction of HgBr2, HgBr3−, and HgBr42− in ice is more efficient than in the gas phase. This results from the influence of water molecules on the molecular geometry and electronic structure of mercuric bromides in ice, which enhances the absorption intensities at wavelengths relevant in the troposphere (λ > 290 nm), as compared to gas phase. Kinetic modeling shows that ~30 to 60% of deposited mercury in AMDEs can be reemitted due to the photoreduction of mercuric bromides in ice, in agreement with field observations. Our results reveal a photoreduction mechanism of sunlight-induced excited state chemistry of mercuric bromides on ice. These findings strongly suggest that this chemistry should be incorporated into atmospheric models to account for ice-atmosphere mercury cycling in the polar environments, currently not considered.The project that gave rise to these results received the support of a fellowship for J.C.- G. from “la Caixa” Foundation (ID 100010434); the fellowship code is LCF/BQ/DR20/11790027. This work is also supported by the Spanish Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación and the European Regional Development Fund through Project PID2021- 127199NB- I00 and by the Conselleria de Educación, Cultura, Universidades y Empleo of the Generalitat Valenciana through Project CIAICO/2022/121. A.B.- S. is thankful to the Generalitat Valenciana for funding support by the postdoctoral fellowship contract APOSTD/2022/027. Indian Institute of Tropical Meteorology is funded by the Ministry of Earth Sciences, Government of India. F.W. acknowledges the support of the Canada Research Chairs program. A.F. acknowledges support from Horizon Europe Marie Skłodowska- Curie Grant Agreement No. 101103544. This work represents a contribution to the Spanish National Research Council (CSIC) Interdisciplinary Thematic Platform (PTI) Polar zone Observatory (PTI- POLARCSIC).Peer reviewe
A histological procedure for the study of insect chitinized tissues in light microscopy
No full textWe present a procedure to obtain histological preparations of insect cuticles for their observation in ligth microscopy. The use of EDTA (ethylendiaminetetraacetic acid), as a chelator of certain metals present in chitin, soften the tissues and allows us to cut them. The tissues were embbeding in plastic resines in two different protocols and cutted by cryostat (20–30 μ m) and ultramicrotome (4 μ m) respectively. This procedure, based on traditional histology products, allows us to obtain preparations observable under an optical microscope, facilitating the study of the internal structure of the cuticule, e.g. visualizing the different layers or structures such as glands or setae.Peer reviewe
Photoswitching Histone Deacetylase Inhibitors for the Spatiotemporal Targeting of Cancer Cells With Light
No full textLos dispositivos DGT como herramienta útil para la determinación de mercurio biodisponible en sistemas acuáticos y terrestres
No full textManteros
No full textManteros are street vendors, mainly from Senegal and with a precarious legal status, who since the 1980s have used the urban public space for their economic activities. In this entry, we focus on the process of persecution and criminalization they have suffered since the middle of the last decade in cities such as Barcelona and Madrid, as well as on the forms of solidarity, resistance and protest they have articulated through, fundamentally, the creation of the Sindicato Popular de Vendedores Ambulantes (Popular Union of Street Vendors). This case is illustrative of many of the current debates around the right to the city, as well as some of the forms that increasingly robust migrant activism has taken.Peer reviewe
Deep mantle anomalies and their surface dynamic topographic response
No full textThe topography is shaped by isostasy but also by dynamic topography driven by stresses caused by mantle flow. We calculated the dynamic topography along our modeled deep structure of Adria-Dacia microplates. The mantle flow generated by the slabs along the western and eastern Adria margins results in some viscous stresses transmitted to surface. We discuss them in terms of the geodynamic process of the region and the surface observation
Considerations on fleet classification in the northern GSA 6 (ICATMAR, 25-02)
No full text6 pages, 2 figures, 3 tablesThese considerations aim to contribute to the ongoing debate on the segmentation of the EU fleet into categories with the available information from our regionWith the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe
Advancing Antarctic sediment chronology through combined ramped pyrolysis oxidation and pyrolysis-GC-MS
Get PDFSelected Papers from the 24th Radiocarbon and 10th Radiocarbon & Archaeology International Conferences, Zurich, Switzerland, 11–16 Sept. 2022Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.CEG, SN, JCT, AZ, SR, JPT, AMP acknowledge that development and application of RPO-AMS and Py-GC-MS techniques was funded by the New Zealand Ministry of Business, Innovation and Employment (MBIE) through the Global Change Through Time research programme and Capability Development Fund (contract C05X1702). JCT, CEG, and AZ acknowledge the entire technical staff at Rafter Radiocarbon Laboratory, and in particular M. Norris and J. Dahl. RHL acknowledges that case study one was supported in part, by the New Zealand Ministry of Business Innovation and Employment through the Antarctic Science
Platform (ANTA1801) and Past Antarctic Climate Programme contract C05X1001. KCY acknowledges the Ministry of Oceans and Fisheries (KOPRI PE23090) for further support of case study one. GD and TC acknowledge that case study two research was funded by the Aotearoa New Zealand Antarctic Science Platform (ANTA1801) Antarctic Ice Dynamics Project (ASP02101). CE and JGP acknowledge funding for case study three through Spanish Ministry of Science and Innovation (grant CTM2017-89711-C2-1-P), co-funded by the European Union through FEDER funds, and the samples from the International Ocean
Drilling Program (Expedition 318), and the Insituto Andaluz de Ciencias del Tierra (CSIC-UGR)