The electromagnetic and gravitational-wave radiations of X-ray transient CDF-S XT2

Binary neutron star(NS)mergers may result in remnants of supra-massive or even stable NS,which have been supported indirectly by observed X-ray plateau of some gamma-ray burst(GRB)afterglows.Recently,Xue et al.(2019)discovered an X-ray transient CDF-S XT2 that is powered by a magnetar from merger of double NS via X-ray plateau and following stepper phase.However,the decay slope after the plateau emission is slightly larger than the theoretical value of spin-down in electromagnetic(EM)dominated by losing its rotation energy.In this paper,we assume that the feature of X-ray emission is caused by a supra-massive magnetar central engine for surviving thousands of seconds to collapse into a black hole.Within this scenario,we present the comparisons of the X-ray plateau luminosity,break time,and the parameters of magnetar between CDF-S XT2 and other short GRBs with internal plateau samples.By adopting the collapse time to constrain the equation of state(EOS),we find that three EOSs(GM1,DD2,and DDME2)are consistent with the observational data.On the other hand,if the most released rotation energy of magnetar is dominated by GW radiation,we also constrain the upper limit of ellipticity of NS for given EOS,and its range is[0.32-1.3]×10^-3.Its GW signal cannot be detected by Advanced LIGO or even for more sensitive Einstein Telescope in the future.     

Towards high‐resolution 3D marine seismic surveying using Boomer sources

The use of Boomer sources for 3D seismic imaging of shallow marine structures was investigated in a feasibility study. Boomers show sufficient stability to be used in multichannel seismic surveys. The acquisition of a high-frequency, densely sampled seismic data volume was successfully performed in the Baltic Sea. A Pleistocene fluvial channel system and shallow gas accumulations were revealed beneath the unconsolidated sediments which constitute the sea-floor in the southern Kiel Bay.     

Die Geologie der Schottischen Hochlande

Zusammenfassung Die drei großen geologischen Einheiten der Schottischen Hochlande — der Block des Hebridenkratons im Nordwesten, die Zone der kaledonischen Überschiebungen und das Gebiet der kaledonischen Geosynklinale mit den Sedimenten der Moine Series und des Dalradian — sind weiterhin Gegenstand zahlreicher tektonischer, petrographischer, stratigraphischer und sedimentologischer Untersuchungen gewesen. Besonders hervorzuheben sind die Aufgliederung des Lewisian durch zwei metamorphe Zyklen, die tektonischen Arbeiten im Bereich der Überschiebungszone, die eine Unzahl noch ungeklärter Fragen aufwerfen, und stratigraphisch-sedimentologische Untersuchungen in Moine und Dalradian. Eingehende Arbeiten sind dem Problem der Lewisian Inliers gewidmet, die in einigen Fällen als hochmetamorphe Äquivalente der Moine Series nachgewiesen werden konnten.     

Comparison of near-fault and far-fault ground motion effects on geometrically nonlinear earthquake behavior of suspension bridges

This paper presents a comparison of near-fault and far-fault ground motion effects on geometrically nonlinear earthquake behavior of suspension bridges. Bo?azi?i (The First Bosporus) and Fatih Sultan Mehmet (Second Bosporus) suspension bridges built in Istanbul, Turkey, are selected as numerical examples. Both bridges have almost the same span. While Bo?azi?i Suspension Bridge has inclined hangers, Fatih Sultan Mehmet Suspension Bridge has vertical hangers. Geometric nonlinearity including P-delta effects from self-weight of the bridges is taken into account in the determination of the dynamic behavior of the suspension bridges for near-fault and far-fault ground motions. Near-fault and far-fault strong ground motion records, which have approximately identical peak ground accelerations, of 1999 Chi-Chi, 1999 Kocaeli, and 1979 Imperial Valley earthquakes are selected for the analyses. Displacements and internal forces of the bridges are determined using the finite element method including geometric nonlinearity. The displacements and internal forces obtained from the dynamic analyses of suspension bridges subjected to each fault effect are compared with each other. It is clearly seen that near-fault ground motions are more effective than far-fault ground motion on the displacements and internal forces such as bending moment, shear force and axial forces of the suspension bridges.     

Convective cores in galactic cooling flows

We use hydrodynamic simulations with adaptive grid refinement to study the dependence of hot gas flows in X-ray luminous giant elliptical galaxies on the efficiency of heat supply to the gas. We consider a number of potential heating mechanisms including Type Ia supernovae and sporadic nuclear activity of a central supermassive black hole. As a starting point for this research we use an equilibrium hydrostatic recycling model. We show that a compact cooling inflow develops, if the heating is slightly insufficient to counterbalance radiative cooling of the hot gas in the central few kiloparsecs. An excessive heating in the centre, instead, drives a convectively unstable outflow. We model the onset of the instability and a quasi-steady convective regime in the core of the galaxy in two dimensions assuming axial symmetry.
Provided the power of net energy supply in the core is not too high, the convection remains subsonic. The convective pattern is dominated by buoyancy driven large-scale mushroom-like structures. Unlike in the case of a cooling inflow, the X-ray surface brightness of an (on average) isentropic convective core does not display a sharp maximum at the centre. A hybrid model, which combines a subsonic peripheral cooling inflow with an inner convective core, appears to be stable. We also discuss observational implications of these results.     

Probabilistic seismic hazard assessment of Eastern Marmara Region

The objective of this study is to evaluate the seismic hazard in Eastern Marmara Region using an improved probabilistic seismic hazard assessment methodology. Two significant improvements over the previous seismic hazard assessment practices are accomplished in this study: advanced seismic source characterization models in terms of source geometry and recurrence relationships are developed, and improved global ground motion models (NGA-W1 models) are employed to represent the ground motion variability. Planar fault segments are defined and a composite magnitude distribution model is used for all seismic sources in the region to properly represent the characteristic behavior of the North Anatolian Fault without the need for an additional background zone. Multi-segment ruptures are considered using the rupture model proposed by the Working Group on California Earthquake Probabilities (2003). Events in the earthquake catalogue are attributed to the fault zones and scenario weights are determined by releasing the accumulated seismic energy. The uniform hazard spectra at 10 % probability of exceedance in 50 years hazard level for different soil conditions (soil and rock) are revealed for specific locations in the region (Adapazar?, Düzce, Gemlik, Izmit, Iznik and Sapanca). Hazard maps of the region for rock site conditions at the selected hazard levels are provided to allow the readers perform site-specific hazard assessment and develop site-specific design spectrum for local site conditions.     

Some consequences of meteoroid impacts on Saturn's rings

High-velocity impacts of interplanetary meteoroids on Saturn's rings are discussed. It is shown that the neutral gas emitted by impact vaporization may be responsible, to a large part, for the observed neutral ring atmosphere. Both the predicted neutral gas injection rate and the gas temperature (or kinetic energy) are compatible with the measurements (see Broadfoot, A. L., B. R. Sandel, D. E. Shemansky, J. B. Holberg, G. R. Smith, D. F. Strobel, J. C. McConnell, S. Kumar, D. M. Hunten, S. K. Atreya, T. M. Dohnahne, H. W. Moos, J. L. Bertaux, J. E. Blamont, R. B. Pomphrey, and S. Linik, Science212, 206–211, 1981). Heavy ejecta particles produce a particulate ring “halo”. The physical properties of this halo are calculated, and it appears to be identical with the tenous particle population discussed by Baum and Kreidl (1982). Erosion of Saturn's ring particles, the resulting mass balance, and regolith formation are estimated. This provides some constraints on surface properties and optical albedo.     

Neue Ergebnisse ans der Grenzregion zwischen der Flyschzone und den nördlichen Kalkalpen

Zusammenfassung Es wurden in großen Zügen Schichtfolge, paläogeographische Entwicklung und Tektonik im österreichischen Verbreitungsgebiet einer schmalen, größtenteils stark verschuppten Zone beschrieben, die sich zwischen der Flyschzone und den nördlichen Kalkalpen erstreckt. Sie wurde bisher für die westliche Fortsetzung der karpatischen pieninischen Klippenzone gehalten. Es konnte nachgewiesen werden, daß letztere etwa im Lainzer Tiergarten bei Wien ihr westliches Ende findet, die Grestener Schuppenzone, wie erstere bezeichnet werden soll, dagegen eine nördlichere Einheit darstellt, die mit der inneren oder Waagtaler Klippenregion der Karpaten identisch ist.Im Wiener Wald ist sie noch ziemlich breit, einfach gebaut und auch in fazieller Hinsicht dem Flysch sehr ähnlich. In dem Maße aber, in dem sie gegen Westen immer mehr von den Kalkalpen überschoben und damit schmäler wird, kompliziert sich auch ihr Bau. Aus Oberbayern, Allgäu und Westschweiz ist sie schließlich nur noch in Form vereinzelter Schubfetzen (Aroser Schuppenzone) bekannt.Bezeichnend sind Schuppen, die an ihrer Basis aus — bisher irreführenderweise Klippen genannten — jurassisch-neokomen Sandsteinen, Kalken, Mergeln usw., im Hangenden dagegen aus kretazisch-eozänen Hüllschichten in Flyschfazies bestehen.Bis zur Unterkreide lag der Sedimentationsraum dieser Zone am Nordrand der kalkalpinen Geosynklinale. Als sich darauf das Flyschbecken einsenkte, geriet er im Westen in den Schwellenbereich am Südrand dieses Beckens. Im Osten, d. h. im Wiener Wald und in den Westkarpaten, fehlen dagegen die trennenden Schwellen, so daß das Flyschmeer dort viel weiter nach Süden reichte.Die Grestener Schuppenzone nimmt also in paläogeographischer und tektonischer Hinsicht eine zwischen Flyschzone und nördlichen Kalkalpen vermittelnde Stellung ein.     

Shallow sediment deformation styles in north-western Campeche Knolls,Gulf of Mexico and their controls on the occurrence of hydrocarbon seepage

During German R/V Meteor M67/2 expedition to Campeche Knolls, southern Gulf of Mexico, a set of 2D high resolution seismic data was acquired to study the near-surface sediment structure and its relationship with hydrocarbon seepages in this salt province. The comprehensive survey covered 20 individual bathymetric highs or ridges and identified three principle structural types: Passive Type, Chaopopte Type, and Asymmetric Flap Type. The first type is the result of passive diapirism, whereas the latter two were initialized by a regional compressional event in the Miocene, but are later differently modified by salt tectonism. Chapopote Type structures appear as symmetrical domes, with uplifted coarse-grained Miocene sediments in their cores and rather thin syn-kinematic sediments covering the crests. Asymmetric Flap Type structures are also first folded as domes or ridges, but one flap later subsided together with salt evacuation, resulting in single uplifted monoclines. With the coarse-grained pre-kinematic sediments as reservoir units, both structural types can focus and accumulate hydrocarbons. The geometries of the structures suggest that hydrocarbons are accumulated in the center of the Chapopote Type structures and in the subsided flaps of the Asymmetric Flap Type structures. Hydrocarbon leakage from these thinly sealed reservoirs is regarded as the principle mechanism for the seepage in the study area, and accordingly the most seepage-prone positions are above these reservoirs. The seep locations suggested by analysis of sea-surface oil slick images of SAR satellite data are also examined in this study. These independently derived seep locations confirm the seepage-prone positions to be above the shallow buried reservoirs. This study suggest that the shallow sediment structures control the distribution of the hydrocarbon seeps of the north-western Campeche Knolls, although the hydrocarbons are sourced from the greater depth.     

Anthropogenic affects on lake sedimentation process: a case study from Lake Sapanca, NW Turkey

Lake Sapanca in NW Turkey is a fault originated freshwater basin fed by seasonally variable flows of 15 streams. Considerations of lake–river interaction, supported by statistical measures of 47 bottom samples, suggest that sediment transport and deposition within the lake is controlled by two types of human constructed structures in addition to natural factors: (1) the dykes constructed in the front of streams, which feed the lake by strong flows, to prevent the filling of lakebed by coarse-grained sediments; (2) the constructed regulator on the outflowing Çarksuyu stream results in a higher sedimentation rate of clay-sized material on the NE corner of the lake, which is extraordinary in the shelf environment.