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Diego F. Torres Shu Zhang Olaf Reimer Xavier Barcons Amalia Corral Valentí Bosch-Ramon Josep M. Paredes Gustavo E. Romero Jin Qu Werner Collmar Volker Schönfelder Yousaf Butt 《Astrophysics and Space Science》2007,309(1-4):17-21
The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the
only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically
significant sources (likelihood >10) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932,
is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the
COMPTEL source position uncertainty make an association hard to quantify and thus risky. At the best location of the source,
detections at hard X-rays show only upper limits, which, together with MeV results obtained by COMPTEL suggest the existence
of a peak in power output located somewhere between 300–700 keV for the so-called low state. Such a spectrum resembles those
in blazars or microquasars, and might suggest at work by the models accordingly. However, an analysis using a microquasar
model consisting on a magnetized conical jet filled with relativistic electrons, shows that it is hard to comply with all
observational constrains. This fact and the non-detection at hard X-rays introduce an a-posteriori question mark upon the
physical reality of this source, what is discussed here. 相似文献
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Arias-Molinares Daniela García-Palomares Juan Carlos Romanillos Gustavo Gutiérrez Javier 《Journal of Geographical Systems》2023,25(3):403-427
Journal of Geographical Systems - In the past ten years, cities have experienced a burst of micromobility services as they offer a flexible transport option that allows users to cover short trips... 相似文献
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Rafael Rosolem Hoshin V. Gupta W. James Shuttleworth Luis Gustavo Gonçalves de Gonçalves Xubin Zeng 《水文研究》2013,27(14):2075-2097
In climate models, the land–atmosphere interactions are described numerically by land surface parameterization (LSP) schemes. The continuing improvement in realism in these schemes comes at the expense of the need to specify a large number of parameters that are either directly measured or estimated. Also, an emerging problem is whether the relationships used in LSPs are universal and globally applicable. One plausible approach to evaluate this is to first minimize uncertainty in model parameters by calibration. In this paper, we conduct a comprehensive analysis of some model diagnostics using a slightly modified version of the Simple Biosphere 3 model for a variety of biomes located mainly in the Amazon. First, the degree of influence of each individual parameter in simulating surface fluxes is identified. Next, we estimate parameters using a multi‐operator genetic algorithm applied in a multi‐objective context and evaluate simulations of energy and carbon fluxes against observations. Compared with the default parameter sets, these parameter estimates improve the partitioning of energy fluxes in forest and cropland sites and provide better simulations of daytime increases in assimilation of net carbon during the dry season at forest sites. Finally, a detailed assessment of the parameter estimation problem was performed by accounting for the decomposition of the mean squared error to the total model uncertainty. Analysis of the total prediction uncertainty reveals that the parameter adjustments significantly improve reproduction of the mean and variability of the flux time series at all sites and generally remove seasonality of the errors but do not improve dynamical properties. Our results demonstrate that error decomposition provides a meaningful and intuitive way to understand differences in model performance. To make further advancements in the knowledge of these models, we encourage the LSP community to adopt similar approaches in the future. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Valentí Bosch-Ramon Gustavo E. Romero Josep M. Paredes 《Astrophysics and Space Science》2005,297(1-4):119-129
Population studies of EGRET gamma-ray sources indicate that there is a distinctive population of bright sources at low galactic
latitudes. The sources have a distribution consistent with that of young galactic objects, with a concentration toward the
inner spiral arms. There is a subgroup that displays strong variability with timescales from days to months. Following an
earlier suggestion by Kaufman Bernadó et al. (2002), we explore the possibility that these sources could be high-mass microquasars.
Detailed models for the gamma-ray emission that include inverse Compton interactions of electrons in the relativistic jets
and photons from all local fields (stellar UV photons, synchrotron photons, soft X-ray photons from the accretion disk, and
hard X-ray photons from a corona) are presented. We conclude that microquasars are excellent candidates for the parent population
of the subgroup of variable low-latitude EGRET sources. 相似文献
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