The submillimetre properties of gamma-ray burst host galaxies     

N. R. Tanvir  V. E. Barnard  A. W. Blain  A. S. Fruchter  C. Kouveliotou  P. Natarajan  E. Ramirez-Ruiz  E. Rol  I. A. Smith  R. P. J. Tilanus  R. A. M. J. Wijers 《Monthly notices of the Royal Astronomical Society》2004,352(3):1073-1080

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The extreme, red afterglow of GRB 060923A: distance or dust?     

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   

An Injectable Apatite Permeable Reactive Barrier for In Situ 90Sr Immobilization     

Vince R. Vermeul  Jim E. Szecsody  Brad G. Fritz  Mark D. Williams  Robert C. Moore  Jonathan S. Fruchter 《Ground Water Monitoring & Remediation》2014,34(2):28-41

An injectable permeable reactive barrier (PRB) technology was developed to sequester ⁹⁰Sr in groundwater through the in situ formation of calcium‐phosphate mineral phases, specifically apatite that incorporates ⁹⁰Sr into the chemical structure. This injectable barrier technology extends the PRB concept to sites where groundwater contaminants are too deep or where site conditions otherwise preclude the application of more traditional trench‐emplaced barriers. An integrated, multiscale development and testing approach was used that included laboratory bench‐scale experiments, an initial pilot‐scale field test, and the emplacement and evaluation of a 300‐feet‐long treatability‐test‐scale PRB. The apatite amendment formulation uses two separate precursor solutions, one containing a Ca‐citrate complex and the other a Na‐phosphate solution, to form apatite precipitate in situ. Citrate is needed to keep calcium in solution long enough to achieve a more uniform and areally extensive distribution of precipitate formation. In the summer of 2008, the apatite PRB technology was applied as a 91‐m‐long (300 feet) PRB on the downgradient edge of a ⁹⁰Sr plume beneath the Hanford Site in Washington State. The technology was deployed to reduce ⁹⁰Sr flux discharging to the Columbia River. Performance assessment monitoring data collected to date indicate that the barrier is meeting treatment objectives (i.e., 90% reduction in ⁹⁰Sr concentration). The average reduction in ⁹⁰Sr concentrations at four downgradient compliance monitoring locations was 95% relative to the high end of the baseline range approximately 1 year after treatment, and continues to meet remedial objectives more than 4 years after treatment.  相似文献   

Strontium stable isotopes fractionate in the soil environments?   总被引：1，自引：0，他引：1  

Ludwik Halicz  Irina Segal  Noa Fruchter  Mordechai Stein  Boaz Lazar   《Earth and Planetary Science Letters》2008,272(1-2):406-411

This study shows that the stable isotopic composition of strontium (the ⁸⁸Sr/⁸⁶Sr ratio expressed as δ^88/86Sr value relative to the NBS987 standard) varies significantly in sedimentary terrestrial environments. The abundances of ⁸⁶Sr, ⁸⁸Sr isotopes were analyzed by MC-ICP-MS “Nu Plasma”. All studied rocks and waters show δ^88/86Sr values that are distinctly different from the measured NBS987 standard (yielding 0.01 ± 0.05‰, all errors are reported as 2σ). Modern corals from the northern Gulf of Aqaba, Red Sea yielded significantly different value than seawater (δ^88/86Sr = 0.22 ± 0.07‰, compared to 0.35 ± 0.06‰, respectively), in an excellent correlation with the δ^88/86Sr analyses reported by Fietzke and Eisenhauer [Fietzke, J., Eisenhauer, A., 2006. Determination of temperature-dependent stable strontium isotopes (⁸⁸Sr/⁸⁶Sr) fractionation via bracketing standard MC-ICP-MS. Geochm. Geophys. Geosyst. 7 (no. 8)] on other coral samples. All carbonate samples that originated in the marine environment: corals (porites and acropora from the northern Gulf of Aqaba); Cretaceous limestone and runoff from the Judea Mountains as well as lacustrine evaporitic aragonite (Dead Sea); and Red Sea and Atlantic seawater yield an average δ^88/86Sr value of 0.26 ± 0.1‰. On the other hand, secondary materials (products of chemical weathering) from the terrestrial environment of the Judea Mountain such as terra rossa soil and speleothem calcite (that derives its Sr from the above-lying soil) yielded significantly lower δ^88/86Sr value of − 0.17 ± 0.06‰. This indicates that strontium isotopes fractionate in the soil environment calling for a possible development of strontium isotopes as a tracer for processes of chemical weathering and pedogenesis.  相似文献   

Millimetric properties of gamma-ray burst host galaxies     

R. S. Priddey  N. R. Tanvir  A. J. Levan  A. S. Fruchter  C. Kouveliotou  I. A. Smith  R. A. M. J. Wijers 《Monthly notices of the Royal Astronomical Society》2006,369(3):1189-1195

We present millimetre (mm) and submillimetre (submm) photometry of a sample of five host galaxies of gamma-ray bursts (GRBs), obtained using the Max Planck Millimetre Bolometer (MAMBO2) array and Submillimetre Common-User Bolometer Array (SCUBA). These observations were obtained as part of an ongoing project to investigate the status of GRBs as indicators of star formation. Our targets include two of the most unusual GRB host galaxies, selected as likely candidate submm galaxies: the extremely red  ( R − K ≈ 5)  host of GRB 030115, and the extremely faint  ( R > 29.5)  host of GRB 020124. Neither of these galaxies is detected, but the deep upper limits for GRB 030115 impose constraints on its spectral energy distribution, requiring a warmer dust temperature than is commonly adopted for submillimetre galaxies (SMGs).
As a framework for interpreting these data, and for predicting the results of forthcoming submm surveys of Swift -derived host samples, we model the expected flux and redshift distributions based on luminosity functions of both submm galaxies and GRBs, assuming a direct proportionality between the GRB rate density and the global star formation rate density. We derive the effects of possible sources of uncertainty in these assumptions, including (1) introducing an anticorrelation between GRB rate and the global average metallicity, and (2) varying the dust temperature.  相似文献   

Deep radio observations of the rich globular clusters Terzan 5 and Liller 1     

A. S. Fruchter  W. M. Goss 《Journal of Astrophysics and Astronomy》1995,16(2):245-253

We have obtained deep 6, 20 and 90 cm observation of two of the richest globular clusters in the galaxy, Terzan 5 and Liller 1. In addition to the well known eclipsing pulsar, PSR1744-24A, our 20 cm image of Terzan 5 displays numerous point sources within 30″, or 4 core radii of the cluster center. The density of these objects rises rapidly toward the core, where an elongated region of emission is found. This feature may be due to the presence of a higher density of point sources than can be resolved by the 1″ resolution of our data. Observations at 6 and 90 cm show that the brightest individual sources, as well as the extended emission, possess the steep spectra expected of pulsars. Furthermore, we find that the strength of the sources in the 20 cm image agrees well with the standard pulsar luminosity function. The total luminosity and number of objects observed in Terzan 5 suggest that this cluster may contain 100 pulsars — probably more than any other Galactic cluster. Although we do not resolve individual sources in Liller 1, comparison of our images with other observations suggests that we are again observing the sum of emission from a number of objects. The 90 cm flux densities of Terzan 5 and Liller 1 are 35 and 9 mJy, respectively, implying that a number of bright pulsars in these clusters have been hidden from pulsed searches, perhaps by a combination of dispersion smearing, scattering and doppler broadening.  相似文献   

Simple Spring-mass Model Simulation of Earthquake Cycle along the Nankai Trough in Southwest Japan   总被引：1，自引：0，他引：1  

Noa Mitsui  Kazuro Hirahara 《Pure and Applied Geophysics》2004,161(11-12):2433-2450

— Along the Nankai trough in southwest Japan, due to the subduction of the Philippine Sea plate, great earthquakes have occurred repeatedly. The rupture zone is divided into five segments. Historical documents show the characteristic features of the past several earthquake cycles, such as almost simultaneous rupture occurrence in segments in spite of different convergence rates, the recurrence time of 90 to 150 years, the existence of segment pairing in earthquake ruptures and the different coseismic slip behaviors in respective segments. Based on the rate and state friction law, we simulate these features with a simple block-spring model to investigate the physical mechanisms of earthquake cycle. Considering the actual fault parameters related to the geometry and the kinematics of the convergent plate in five segments, we calculate the model parameters for the corresponding blocks in the simulation. The features of the observed earthquake cycle are successfully reproduced by assigning the other following model parameters; (1) the stick-slip periods are the same (more than 150 years) for non-interacting blocks, (2) the different pairs of frictional parameters a-b and D _c are assigned in each segment, (3) the interactions between segments are large, (4) the convergence rate in the eastern Tokai segment is about half of those in the other segments.  相似文献   

In Situ Redox Manipulation by Dithionite Injection: Intermediate-Scale Laboratory Experiments     

J.D. Istok  J.E. Amonette  C.R. Cole  J.S. Fruchter  M.D. Humphrey  J.E. Szecsody  S.S. Teel  V.R. Vermeul  M.D. Williams  S.B. Yabusaki 《Ground water》1999,37(6):884-889

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The light curve of the companion to PSR B1957+20     

M. T. Reynolds  P. J. Callanan  A. S. Fruchter  M. A. P. Torres  M. E. Beer  R. A. Gibbons 《Monthly notices of the Royal Astronomical Society》2007,379(3):1117-1122

We present a new analysis of the light curve for the secondary star in the eclipsing binary millisecond pulsar system PSR B1957+20. Combining previous data and new data points at minimum from the Hubble Space Telescope , we have 100 per cent coverage in the R -band. We also have a number of new K _s-band data points, which we use to constrain the infrared magnitude of the system. We model this with the eclipsing light-curve (ELC) code. From the modelling with the ELC code we obtain colour information about the secondary at minimum light in BVRI and K . For our best-fitting model we are able to constrain the system inclination to 65°± 2° for pulsar masses ranging from 1.3 to  1.9  M_⊙  . The pulsar mass is unconstrained. We also find that the secondary star is not filling its Roche lobe. The temperature of the unirradiated side of the companion is in agreement with previous estimates and we find that the observed temperature gradient across the secondary star is physically sustainable.  相似文献   

Lunar polymict breccia 14321: a compositional study of its principal components     

A.R Duncan  S.M Mckay  J.W Stoeser  M.M Lindstrom  D.J Lindstrom  J.S Fruchter  G.G Goles 《Geochimica et cosmochimica acta》1975,39(3):247-260

Forty-nine sub-samples of the polymict breccia 14321,184 have been excavated from the rock and analysed by instrumental activation analysis techniques, specially modified to allow examination of small samples. Two distinct types of microbreccia clasts were analysed. A mare-type basalt of unusual composition is present as several discrete clasts. Mixing models for the clastic components of the breccia illustrate that at least three stages of assembly may be distinguished on compositional grounds. The first was at a site such that KREEP-rich materials dominated the clastic rocks formed, although a variety of lithic fragments were apparently present. The second assembly stage may have been primarily that of comminution and mixing of the more primitive materials, with addition of mare-type basalt elasts. The third stage saw addition of clasts of 14321-type basalt. In the final assembly stage the light matrix was apparently formed entirely by mutual abrasion of the pre-existing clasts, resulting in little or no change in bulk composition  相似文献