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N. R. Tanvir A. J. Levan E. Rol R. L. C. Starling J. Gorosabel R. S. Priddey D. Malesani P. Jakobsson P. T. O'Brien A. O. Jaunsen J. Hjorth J. P. U. Fynbo A. Melandri A. Gomboc B. Milvang-Jensen A. S. Fruchter M. Jarvis C. A. C. Fernandes T. Wold 《Monthly notices of the Royal Astronomical Society》2008,388(4):1743-1750
Gamma-ray bursts (GRBs) are powerful probes of the early Universe, but locating and identifying very distant GRBs remain challenging. We report here the discovery of the K -band afterglow of Swift GRB 060923A, imaged within the first hour post-burst, and the faintest so far found. It was not detected in any bluer bands to deep limits, making it a candidate very high- z burst ( z ≳ 11) . However, our later-time optical imaging and spectroscopy reveal a faint galaxy coincident with the GRB position which, if it is the host, implies a more moderate redshift (most likely z ≲ 2.8 ) and therefore that dust is the likely cause of the very red-afterglow colour. This being the case, it is one of the few instances so far found of a GRB afterglow with high-dust extinction. 相似文献
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R. Wijnands E. Rol E. Cackett R. L. C. Starling R. A. Remillard 《Monthly notices of the Royal Astronomical Society》2009,393(1):126-132
We present an analysis of the Swift Burst Alert Telescope (BAT) and X-ray telescope (XRT) data of GRB060602B, which is most likely an accreting neutron star in a binary system and not a gamma-ray burst. Our analysis shows that the BAT burst spectrum is consistent with a thermonuclear flash (type I X-ray burst) from the surface of an accreting neutron star in a binary system. The X-ray binary nature is further confirmed by the report of a detection of a faint point source at the position of the XRT counterpart of the burst in archival XMM–Newton data approximately six year before the burst and in more recent XMM–Newton data obtained at the end of 2006 September (nearly four months after the burst). Since the source is very likely not a gamma-ray burst, we rename the source Swift J1749.4−2807, based on the Swift /BAT discovery coordinates. Using the BAT data of the type I X-ray burst, we determined that the source is at most at a distance of 6.7 ± 1.3 kpc . For a transiently accreting X-ray binary, its soft X-ray behaviour is atypical: its 2–10 keV X-ray luminosity (as measured using the Swift /XRT data) decreased by nearly three orders of magnitude in about 1 day, much faster than what is usually seen for X-ray transients. If the earlier phases of the outburst also evolved this rapidly, then many similar systems might remain undiscovered because the X-rays are difficult to detect and the type I X-ray bursts might be missed by all the sky surveying instruments. This source might be part of a class of very fast transient low-mass X-ray binary systems of which there may be a significant population in our Galaxy. 相似文献
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In November 2002, the sinking of the Prestige cargo ship produced an oil spill of 60,000 tons that affected many areas along the Galician coast (in the northwest of Spain). In a number of rocky shore sites, most organisms (particularly marine mollusks) were nearly extinct at a local scale. We tested whether the local bottleneck/extinction that occurred in affected localities caused any detectable reduction of the genetic diversity in the marine snail Littorina saxatilis, an ovoviviparous rocky shore model species characterized by a low dispersal ability, high population density, and wide distribution range. We compared the level of genetic variation and population differentiation between affected (polluted) and control sites located in seven geographical areas (three sites per area, one impacted and two controls, and two replicates per site) one and a half years after the spill. The analysis included molecular marker variation (microsatellite and AFLP loci) and quantitative trait genetic variation for shell variables in embryos extracted from pregnant females. Our results indicate that the affected populations did not show a significant overall reduction in genetic diversity when compared to the controls, suggesting that the species is highly resistant to losing genetic variability as a consequence of a local short-term pollution process in spite of its low dispersal ability and direct development. However, some genetic effects were detected in the polluted populations, particularly for quantitative shell traits and AFLPs, consistent with local adaptations resulting from the fuel contamination. 相似文献
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Rol Brinkmann 《International Journal of Earth Sciences》1932,23(2):81-88
Ohne ZusammenfassungNach Felduntersuchungen gemeinsam mit H.Gallwitz (Dresden). Vortrag, gehalten auf der Hauptversammlung der Geologischen Vereinigung zu Frankfurt a. M. im Januar 1932. 相似文献
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A. Melandri C. Guidorzi S. Kobayashi D. Bersier C. G. Mundell P. Milne A. Pozanenko W. Li A. V. Filippenko Y. Urata M. Ibrahimov I. A. Steele A. Gomboc R. J. Smith N. R. Tanvir E. Rol K. Huang 《Monthly notices of the Royal Astronomical Society》2009,395(4):1941-1949
We present a comprehensive multiwavelength temporal and spectral analysis of the 'fast rise exponential decay' GRB 070419A. The early-time emission in the γ-ray and X-ray bands can be explained by a central engine active for at least 250 s, while at late times the X-ray light curve displays a simple power-law decay. In contrast, the observed behaviour in the optical band is complex (from 102 up to 106 s). We investigate the light-curve behaviour in the context of the standard forward/reverse shock model; associating the peak in the optical light curve at ∼450 s with the fireball deceleration time results in a Lorenz factor Γ≈ 350 at this time. In contrast, the shallow optical decay between 450 and 1500 s remains problematic, requiring a reverse shock component whose typical frequency is above the optical band at the optical peak time for it to be explained within the standard model. This predicts an increasing flux density for the forward shock component until t ∼ 4 × 106 s , inconsistent with the observed decay of the optical emission from t ∼ 104 s . A highly magnetized fireball is also ruled out due to unrealistic microphysic parameters and predicted light-curve behaviour that is not observed. We conclude that a long-lived central engine with a finely tuned energy injection rate and a sudden cessation of the injection is required to create the observed light curves, consistent with the same conditions that are invoked to explain the plateau phase of canonical X-ray light curves of γ-ray bursts. 相似文献
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C. P. Hurkett J. P. Osborne K. L. Page E. Rol M. R. Goad P. T. O'Brien A. Beardmore O. Godet D. N. Burrows N. R. Tanvir A. Levan B. Zhang D. Malesani J. E. Hill J. A. Kennea R. Chapman V. La Parola M. Perri P. Romano R. Smith N. Gehrels 《Monthly notices of the Royal Astronomical Society》2006,368(3):1101-1109
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