XMM–Newton observations of high-luminosity radio-quiet quasi-stellar objects     

K. L. Page  J. N. Reeves  P. T. O'Brien  M. J. L. Turner  D. M. Worrall 《Monthly notices of the Royal Astronomical Society》2004,353(1):133-142

  相似文献   

Possible remnants of a frozen mud lake in southern Elysium, Mars     

Konrad J. Kossacki  Wojciech J. Markiewicz  David Page 《Icarus》2006,181(2):363-374

In this work we estimate the minimum persistence time of subsurface ice in water rich sediment layers remaining after sublimation of a martian lake. We simulate sublimation of ice from layers of different granulations and thicknesses. Presented results assume insolation and atmospheric conditions characteristic for the present day southern Elysium, where data from Mars Express have identified surface features possibly indicating the very recent presence of a frozen body of water [Murray et al., 2005. Nature 434, 352-356]. The age of these features is estimated to be several million years. On this time scale, we find that most of the water ice must have sublimated away, however remnant ice at a few percent level cannot be excluded. This amount of water ice is sufficient for chemical cementation of the observed features and explains their relatively pristine appearance, without significant signs of erosion.  相似文献   

XMM–Newton 13^H deep field – I. X-ray sources     

N. S. Loaring  T. Dwelly  M. J. Page  K. Mason  I. McHardy  K. Gunn  D. Moss  N. Seymour  A. M. Newsam  T. Takata  K. Sekguchi  T. Sasseen  F. Cordova 《Monthly notices of the Royal Astronomical Society》2005,362(4):1371-1395

  相似文献   

A simultaneous XMM–Newton and BeppoSAX observation of the archetypal broad line Seyfert 1 galaxy NGC 5548     

K. A. Pounds  J. N. Reeves  K. L. Page  R. Edelson  G. Matt  G. C. Perola 《Monthly notices of the Royal Astronomical Society》2003,341(3):953-960

  相似文献   

XMM–Newton observations of 3C 273     

K. L. Page  M. J. L. Turner  C. Done  P. T. O'Brien  J. N. Reeves  S. Sembay  M. Stuhlinger 《Monthly notices of the Royal Astronomical Society》2004,349(1):57-67

  相似文献   

XMM–Newton RGS spectroscopy of LMC X-3     

M. J. Page  R. Soria  K. Wu  K. O. Mason  F. A. Cordova  W. C. Priedhorsky 《Monthly notices of the Royal Astronomical Society》2003,345(2):639-649

  相似文献   

Economically consistent long-term scenarios for air pollutant emissions   总被引：1，自引：0，他引：1  

Steven J. Smith  J. Jason West  Page Kyle 《Climatic change》2011,108(3):619-627

Pollutant emissions such as aerosols and tropospheric ozone precursors substantially influence climate. While future century-scale scenarios for these emissions have become more realistic through the inclusion of emission controls, they still potentially lack consistency between surface pollutant concentrations and regional levels of affluence. We find that the default method of scenario construction, whereby emissions factors converge to similar values in different regions, does not yield pollution concentrations consistent with historical experience. We demonstrate a methodology combining use of an integrated assessment model and a three-dimensional atmospheric chemical transport model, whereby a reference scenario is constructed by requiring consistent surface pollutant concentrations as a function of regional income over the 21st century. By adjusting air pollutant emission control parameters, we improve consistency between projected PM_2.5 and economic income among world regions through time; consistency for ozone is also improved but is more difficult to achieve because of the strong influence of upwind world regions. Reference case pollutant emissions described here were used to construct the RCP4.5 Representative Concentration Pathway climate policy scenario.  相似文献   

Global and regional evolution of short-lived radiatively-active gases and aerosols in the Representative Concentration Pathways   总被引：3，自引：0，他引：3  

Jean-Fran?ois Lamarque  G. Page Kyle  Malte Meinshausen  Keywan Riahi  Steven J. Smith  Detlef P. van Vuuren  Andrew J. Conley  Francis Vitt 《Climatic change》2011,109(1-2):191-212

In this paper, we discuss the results of 2000?C2100 simulations following the emissions associated with the Representative Concentration Pathways (RCPs) with a chemistry-climate model, focusing on the changes in 1) atmospheric composition (troposphere and stratosphere) and 2) associated environmental parameters (such as nitrogen deposition). In particular, we find that tropospheric ozone is projected to decrease (RCP2.6, RCP4.5 and RCP6) or increase (RCP8.5) between 2000 and 2100, with variations in methane a strong contributor to this spread. The associated tropospheric ozone global radiative forcing is shown to be in agreement with the estimate used in the RCPs, except for RCP8.5. Surface ozone in 2100 is projected to change little compared from its 2000 distribution, a much-reduced impact from previous projections based on the A2 high-emission scenario. In addition, globally-averaged stratospheric ozone is projected to recover at or beyond pre-1980 levels. Anthropogenic aerosols are projected to strongly decrease in the 21st century, a reflection of their projected decrease in emissions. Consequently, sulfate deposition is projected to strongly decrease. However, nitrogen deposition is projected to increase over certain regions because of the projected increase in NH₃ emissions.  相似文献   

Land-use transition for bioenergy and climate stabilization: model comparison of drivers,impacts and interactions with other land use based mitigation options   总被引：1，自引：0，他引：1  

Alexander Popp  Steven K. Rose  Katherine Calvin  Detlef P. Van Vuuren  Jan Phillip Dietrich  Marshall Wise  Elke Stehfest  Florian Humpenöder  Page Kyle  Jasper Van Vliet  Nico Bauer  Hermann Lotze-Campen  David Klein  Elmar Kriegler 《Climatic change》2014,123(3-4):495-509

In this article, we evaluate and compare results from three integrated assessment models (GCAM, IMAGE, and ReMIND/MAgPIE) regarding the drivers and impacts of bioenergy production on the global land system. The considered model frameworks employ linked energy, economy, climate and land use modules. By the help of these linkages the direct competition of bioenergy with other energy technology options for greenhouse gas (GHG) mitigation, based on economic costs and GHG emissions from bioenergy production, has been taken into account. Our results indicate that dedicated bioenergy crops and biomass residues form a potentially important and cost-effective input into the energy system. At the same time, however, the results differ strongly in terms of deployment rates, feedstock composition and land-use and greenhouse gas implications. The current paper adds to earlier work by specific looking into model differences with respect to the land-use component that could contribute to the noted differences in results, including land cover allocation, land use constraints, energy crop yields, and non-bioenergy land mitigation options modeled. In scenarios without climate change mitigation, bioenergy cropland represents 10–18 % of total cropland by 2100 across the different models, and boosts cropland expansion at the expense of carbon richer ecosystems. Therefore, associated emissions from land-use change and agricultural intensification as a result of bio-energy use range from 14 and 113 Gt CO2-eq cumulatively through 2100. Under climate policy, bioenergy cropland increases to 24–36 % of total cropland by 2100.  相似文献   

X-ray irradiation in XTE J1817−330 and the inner radius of the truncated disc in the hard state     

Marek Gierli&#;ski  Chris Done  Kim Page 《Monthly notices of the Royal Astronomical Society》2008,388(2):753-760

The key aspect of the very successful truncated disc model for the low/hard X-ray spectral state in black hole binaries is that the geometrically thin disc recedes from the last stable orbit at the transition to this state. This has recently been challenged by direct observations of the low/hard state disc from CCD data. We reanalyse the Swift and RXTE campaign covering the 2006 outburst of XTE J1817−330, and show that these data actually strongly support the truncated disc model as the transition spectra unambiguously show that the disc begins to recede as the source leaves the disc-dominated soft state. The disc radius inferred for the proper low/hard state is less clear-cut, but we show that the effect of irradiation from the energetically dominant hot plasma leads to an underestimate of the disc radius by a factor of 2–3 in this state. This may also produce the soft excess reported in some hard-state spectra. The inferred radius becomes still larger when the potential difference in stress at the inner boundary, increased colour temperature correction from incomplete thermalization of the irradiation, and loss of observable disc photons from Comptonization in the hot plasma is taken into account. We conclude that the inner disc radius in XTE J1817−330 in the low/hard spectral state is at least six to eight times that seen in the disc-dominated high/soft state, and that recession of the inner disc is the trigger for the soft-hard-state transition, as predicted by the truncated disc models.  相似文献