Classifying GRB 170817A/GW170817 in a Fermi duration–hardness plane     

I. Horváth  B. G. Tóth  J. Hakkila  L. V. Tóth  L. G. Balázs  I. I. Rácz  S. Pintér  Z. Bagoly 《Astrophysics and Space Science》2018,363(3):53

GRB 170817A, associated with the LIGO-Virgo GW170817 neutron-star merger event, lacks the short duration and hard spectrum of a Short gamma-ray burst (GRB) expected from long-standing classification models. Correctly identifying the class to which this burst belongs requires comparison with other GRBs detected by the Fermi GBM. The aim of our analysis is to classify Fermi GRBs and to test whether or not GRB 170817A belongs—as suggested—to the Short GRB class. The Fermi GBM catalog provides a large database with many measured variables that can be used to explore gamma-ray burst classification. We use statistical techniques to look for clustering in a sample of 1298 gamma-ray bursts described by duration and spectral hardness. Classification of the detected bursts shows that GRB 170817A most likely belongs to the Intermediate, rather than the Short GRB class. We discuss this result in light of theoretical neutron-star merger models and existing GRB classification schemes. It appears that GRB classification schemes may not yet be linked to appropriate theoretical models, and that theoretical models may not yet adequately account for known GRB class properties. We conclude that GRB 170817A may not fit into a simple phenomenological classification scheme.  相似文献   

Analytical study of ground motion caused by seismic wave propagation across faulted rock masses          下载免费PDF全文

J.C. Li  N.N. Li  S.B. Chai  H.B. Li 《国际地质力学数值与分析法杂志》2018,42(1):95-109

Studying seismic wave propagation across rock masses and the induced ground motion is an important topic, which receives considerable attention in design and construction of underground cavern/tunnel constructions and mining activities. The current study investigates wave propagation across a rock mass with one fault and the induced ground motion using a recursive approach. The rocks beside the fault are assumed as viscoelastic media with seismic quality factors, Q_p and Q_s. Two kinds of interactions between stress waves and a discontinuity and between stress waves and a free surface are analyzed, respectively. As the result of the wave superposition, the mathematical expressions for induced ground vibration are deduced. The proposed approach is then compared with the existing analysis for special cases. Finally, parametric studies are carried out, which includes the influences of fault stiffness, incident angle, and frequency of incident waves on the peak particle velocities of the ground motions.  相似文献   

Genetic variability of the Lessepsian migrant mussel Brachidontes pharaonis (Bivalvia: Mytilidae) in Tunisia     

M Antit  J Urra  AN Alagaili  S Farjallah 《African Journal of Marine Science》2018,40(2):211-217

The present study used two mitochondrial markers (16S rRNA and COI) to assess the genetic diversity of a newly founded Lessepsian migrant mussel, Brachidontes pharaonis, in Tunisian waters. The species appears to be restricted to only one population in Rades Harbour, in the northern part of the country. Phylogenetic analyses revealed the monophyly of B. pharaonis in Tunisia. Both molecular markers revealed high genetic variability of the B. pharaonis population. Haplotype networks and demographic analyses confirmed the recent expansion events within this population. Multiple human-mediated introduction events involving several founder populations and intensive population growth rates are probably the main causes of the high polymorphism observed within this invasive mollusc.  相似文献   

Using Models of the Deep Structure of the Earth’s Crust and Upper Mantle Based on GOCE Gravity Data in Metallogenic Analysis     

Volkov  A. V.  Galyamov  A. L.  Savchuk  Yu. S. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(12):1528-1536

Izvestiya, Atmospheric and Oceanic Physics - Gravimetric data obtained by the GOCE spacecraft contributes to the development of global models of the deep structure of the Earth’s crust and...  相似文献   

Discovery of the First Interstellar Comet and the Spatial Density of Interstellar Objects in the Solar Neighborhood     

Borisov  G. V.  Shustov  B. M. 《Solar System Research》2021,55(2):124-131

Solar System Research - The discovery of the first interstellar comet 2I/Borisov confirmed the astronomers’ speculation that the passage through the solar system of relatively large objects...  相似文献   

Comprehensive Geological–Geophysical and Botanic Study of the Tectonic Junction Zone between the Katun Ridge and Uimon Depression (Altai Mountains)     

Boyarskikh  I. G.  Agatova  A. R.  Kulikova  A. I.  Bakiyanov  A. I.  Skaptsov  M. V.  Mazeika  J. 《Izvestiya Atmospheric and Oceanic Physics》2018,54(8):805-825

Izvestiya, Atmospheric and Oceanic Physics - Areas with large gradients and anomalous variations in geomagnetic and radiation fields have been revealed and mapped at the northwestern foot of the...  相似文献   

The Ni–Antimonide Mineral Assemblage: A Product of Recrystallization of Sn–Pb–Zn Ores of the Yuzhnoe Deposit,Sikhote-Alin,Russia     

Ratkin  V. V.  Simanenko  L. F.  Gonevchuk  V. G.  Eliseeva  O. A. 《Doklady Earth Sciences》2020,492(1):317-319

Doklady Earth Sciences - A mineral assemblage with nisbite NiSb2 and breithauptite NiSb unique for a Mesozoic (Sn)–Pb–Zn vein deposit is found during mineralogical–geochemical...  相似文献   

Mineral Composition of Manganese Crusts from Belyaevskii Volcano (Sea of Japan)     

Volokhin  Yu. G.  Khanchuk  A. I.  Mikhailik  P. E.  Mikhailik  E. V. 《Doklady Earth Sciences》2020,491(2):214-219

Doklady Earth Sciences - The polygenic mineral composition of Mn crusts from Belyaevskii Volcano of the Central Basin of the Sea of Japan is determined. The crusts are found for the first time to...  相似文献   

Extreme Climatic Events in the Altai-Sayan Region as an Indicator of Powerful Volcanic Eruptions     

Barinov  V. V.  Myglan  V. S.  Taynik  A. V.  Oidupaa  O. Ch.  Agatova  A. R.  Churakova  O. V. 《Izvestiya Atmospheric and Oceanic Physics》2018,54(10):1449-1459

Izvestiya, Atmospheric and Oceanic Physics - Analytic data on anomalies of the tree-ring structure of Siberian larch on the transect, passing through the Russian part of the Altai-Sayan Mountain...  相似文献   

Factors influencing biodeposit production by the New Zealand freshwater mussel Echyridella menziesii     

Kevin J. Collier  Susan J. Clearwater  Paula H. M. W. Neijenhuis  Susanna A. Wood 《新西兰海洋与淡水研究杂志》2018,52(1):1-15

Laboratory experiments on the New Zealand freshwater mussel Echyridella menziesii were used to investigate the short-term effects (7–8 days) of food type on rates of biodeposition and benthic substrate respiration. Post-feeding biodeposition rates ranged from 0.34 to 1.52?mg?g^?1?h^?1 (mean?=?0.50?mg g^?1?h^?1) and were unaffected by the addition of toxin-producing Microcystis. Addition of suspended sediment (30?mg?L^?1) visibly altered substrate composition, and increased total and inorganic biodeposit production rates by 24–33% compared to mussels fed commercial phytoplankton stock. Biodeposition rates of mussels in lake bed substrates were 38% higher than those in silica sand for identical feeding regimes, suggesting that a significant proportion of material produced in this experiment could have been derived from feeding on organic matter in the lake bed sediments. Respiration rates were higher in treatments with Microcystis but were unaffected by the presence of mussels. This laboratory study suggests that biodeposition by E. menziesii is resilient to short-term exposure to Microcystis, and highlights the ability of mussels to alter benthic substrate composition by incorporating suspended sediment into substrates.  相似文献