The gravitationally lensed,luminous infrared galaxy IRAS F10214+4724 observed with XMM-Newton     

K. Iwasawa  C. Vignali  A.S. Evans  D.B. Sanders  N. Trentham 《New Astronomy》2010,15(1):58-60

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Mangrove forest sedimentation and its reference to sea level rise,Cananeia, Brazil   总被引：2，自引：2，他引：0  

Christian J. Sanders  Joseph M. Smoak  A. Sathy Naidu  Denise R. Araripe  Lucian M. Sanders  Sambasiva R. Patchineelam 《Environmental Earth Sciences》2010,60(6):1291-1301

The stability of a mangrove ecosystem in Cananeia, Brazil, is assessed based on investigations of the site-specific temporal rise in relative sea level during the past 50 years, 100-year sediment accumulation rates (SAR) and sources of organic matter (OM). Addressing this, three sediment cores were collected in a transect, intertidal mud flat, mangrove margin and well into the forest. The net SAR, as estimated by the age–depth relationships of ²¹⁰Pb and ¹³⁷Cs, is between 2.5 and 3.9 mm year⁻¹. These rates are comparable to the estimates based on the Pb and Zn contaminant markers corresponding to mining initiation in the region in 1918. Further, the SARs are lower than the rate of regional relative sea level rise (4 mm year⁻¹) as indicated by the past 50-year tide gauge record, but the rate is higher than the eustatic sea level rise (1.7 ± 0.3 mm year⁻¹). The stratigraphies of TOC/TN, δ¹³C_(OC), OP and δ¹⁵N indicate site-specific mangal vegetal litter, which is the predominant source of OM at all core sites, during the past century and reflects a stable mangal system over that time span.  相似文献   

Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies     

J. S. Sanders  A. C. Fabian  S. W. Allen  R. G. Morris  J. Graham  R. M. Johnstone 《Monthly notices of the Royal Astronomical Society》2008,385(3):1186-1200

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Predicting tidal flooding of urbanized embayments: A modeling framework and data requirements     

T.W. Gallien  J.E. Schubert  B.F. Sanders 《Coastal Engineering》2011

Numerous urbanized embayments in California are at risk of flooding during extreme high tides caused by a combination of astronomical, meteorologic and climatic factors (e.g., El Niño), and the risk will increase as sea levels rise and storminess intensifies. Across California, the potential exists for billions of dollars in losses by 2100 and predictive inundation models will be relied upon at the local level to plan adaptation strategies and forecast localized flood impacts to support emergency management. However, the predictive skill of urban inundation models for extreme tide events has not been critically examined particularly in relation to data quality and flood mapping methodologies. With a case study of Newport Beach, California, we show that tidal flooding can be resolved along streets and at individual parcels using a 2D hydraulic inundation model that captures embayment amplification of the tide, overtopping of flood defenses, and overland flow along streets and into parcels. Furthermore, hydraulic models outperform equilibrium flood mapping methodologies which ignore hydraulic connectivity and are strongly biased towards over-prediction of flood extent. However, infrastructure geometry data including flood barriers, street and parcel elevations are crucial to accurate flood prediction. A real time kinematic (RTK) survey instrument with an error of approximately 1 cm (RMSE) is found to be suitable for barrier height measurement, but an error of approximately15 cm (RMSE) typical of aerial laser scanning or LiDAR is found to be inadequate. Finally, we note that the harbor waterfront in Newport Beach is lined by a patchwork of public and private parcels and flood barriers of varied designs and integrity. Careful attention to hydraulic connectivity (e.g., low points and gaps in barriers) is needed for successful flood prediction.  相似文献   

Spatially resolved X-ray spectroscopy of the core of the Centaurus cluster     

J. S.Sanders  A. C.Fabian 《Monthly notices of the Royal Astronomical Society》2002,331(2):273-283

We present Chandra data from a 31.7-ks observation of the Centaurus cluster, using the ACIS-S detector. Images of the X-ray emission show a plume-like feature at the centre of the cluster, of extent 60 arcsec (20 kpc in projection). The feature has the same metallicity as gas at a similar radius, but is cooler. Using adaptive binning, we generate temperature, abundance and absorption maps of the cluster core. The radial abundance profile shows that the previously known, steep abundance gradient peaks with a metallicity of  1.3–1.8 Z_⊙  at a radius of about 45 arcsec (15 kpc), before falling back to 0.4 Z_⊙ at the centre of the cluster. A radial temperature profile shows that the temperature decreases inwards. We determine the spatial distributions of each of two temperature components, where applicable. The radiative cooling time of the cooler component within the inner 10 arcsec (3 kpc) is less than  2×10⁷ yr  . X-ray holes in the image coincident with the radio lobes are seen, as well as two outer sharp temperature drops, or cold fronts. The origin of the plume is unclear. The existence of the strong abundance gradient is a strong constraint on extensive convection or gas motion driven by a central radio source.  相似文献   

The extended Hα-emitting filaments surrounding NGC 4696, the central galaxy of the Centaurus cluster     

C. S. Crawford  N. A. Hatch  A. C. Fabian  J. S. Sanders 《Monthly notices of the Royal Astronomical Society》2005,363(1):216-222

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The ultraluminous X-ray sources in the high-velocity system of NGC 1275     

O. González-Martín  A. C. Fabian  J. S. Sanders 《Monthly notices of the Royal Astronomical Society》2006,367(3):1132-1138

We report the results of a study of X-ray point sources coincident with the high-velocity system (HVS) projected in front of NGC 1275. A very deep X-ray image of the core of the Perseus cluster, made with the Chandra X-ray Observatory , has been used. We find a population of ultraluminous X-ray sources [ULXs; seven sources with   L _X(0.5 − 7.0  keV) > 7 × 10³⁹ erg s^-1  ]. As with the ULX populations in the Antennae and Cartwheel galaxies, those in the HVS are associated with a region of very active star formation. Several sources have possible optical counterparts found on the Hubble Space Telescope ( HST ) images, although the X-ray brightest one does not. Absorbed power-law models fit the X-ray spectra, with most having a photon index between 2 and 3.  相似文献   

Chandra observations of Abell 2199     

R. M. Johnstone  S. W. Allen  A. C. Fabian  J. S. Sanders 《Monthly notices of the Royal Astronomical Society》2002,336(1):299-308

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Precession of the super-massive black hole in NGC 1275 (3C 84)?     

R. J. H. Dunn  A. C. Fabian  J. S. Sanders 《Monthly notices of the Royal Astronomical Society》2006,366(3):758-766

The X-ray holes at the centre of the Perseus cluster of galaxies are not all at the same position angle with respect to the centre of the cluster. This configuration would result if the jet inflating the bubbles is precessing, or moving around, and the bubbles detach at different times. The orientations which best fit the observed travel directions are an inclination of the precession axis to the line of sight of 120° and an opening angle of 50°. From the time-scales for the bubbles seen in the cluster, the precession time-scale, τ_prec, is around  3.3 × 10⁷ yr  . The bubbles rising up through different parts of the cluster may have interacted with the central cool gas, forming the whorl of cool gas observed in the temperature structure of the cluster. The dynamics of bubbles rising in fluids is discussed. The conditions present in the cluster are such that oscillatory motion, observed for bubbles rising in fluids on Earth, should take place. However, the time-scale for this motion is longer than that taken for the bubbles to evolve into spherical-cap bubbles, which do not undergo a path instability, so such motion is not expected to occur.  相似文献   

Hydraulic modeling of the 2011 New Madrid Floodway activation: a case study on floodway activation controls   总被引：2，自引：2，他引：0  

Adam Luke  Brad Kaplan  Jeff Neal  Jeremiah Lant  Brett Sanders  Paul Bates  Doug Alsdorf 《Natural Hazards》2015,77(3):1863-1887

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