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Gamma ray emission and stochastic particle acceleration in galaxy clusters 星系团中的伽马射线发射和随机粒子加速
Pub Date : 2008-11-06 DOI: 10.1063/1.3076753
G. Brunetti, P. Blasi, R. Cassano, S. Gabici
FERMI (formely GLAST) will shortly provide crucial information on relativistic particles in galaxy clusters. We discuss non thermal emission in the context of general calculations in which relativistic particles (protons and secondary electrons due to proton‐proton collisions) interact with MHD turbulence generated in the cluster volume during cluster mergers. Diffuse cluster‐scale radio emission (Radio Halos) and hard X‐rays are produced during massive mergers while gamma ray emission, at some level, is expected to be common in galaxy clusters.
费米望远镜不久将提供星系团中相对论性粒子的重要信息。我们在一般计算的背景下讨论非热辐射,其中相对论粒子(质子和由于质子-质子碰撞而产生的次级电子)与团簇合并过程中团簇体积中产生的MHD湍流相互作用。漫射星系团规模的射电发射(射电晕)和硬X射线是在大规模合并期间产生的,而伽马射线的发射,在某种程度上,预计在星系团中是常见的。
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引用次数: 5
Sky-maps of the sidereal anisotropy of galactic cosmic ray intensity and its energy dependence 星系宇宙射线强度的各向异性及其能量依赖性的天空图
Pub Date : 2008-11-04 DOI: 10.1142/9789812838209_0017
K. Munakata, N. Matsumoto, S. Yasue, C. Kato, S. Mori, M. Takita, M. Duldig, J. Humble, J. Kota
We analyze the sidereal daily variations observed between 1985 and 2006 at Matsushiro, Japan (MAT) and between 1993 and 2005 at Liapootah, Tasmania (LPT). These stations comprise the two hemisphere network (THN) of underground muon detectors in Japan and Australia. Yearly mean harmonic vectors at MAT and LPT are more or less stable without any significant change in phase and amplitude in correlation with either the solar activity- or magnetic-cycles. In this paper, therefore, we analyze the average anisotropy over the entire observation periods, i.e. 1985-2006 for MAT and 1993-2005 for LPT. We apply to the THN data a best-fitting analysis based on a model anisotropy in space identical to that adopted by Amenomori et al. (2007) for Tibet III data. The median energies of primary cosmic rays recorded are ~0.5 TeV for THN and ~5 TeV for the Tibet III experiment. It is shown that the intensity distribution of the best-fit anisotropy is quite similar to that derived from Tibet III data, regardless of the order of magnitude difference in energies of primary particles. This, together with the THN observations, confirms that the analysis by Amenomori et al. (2007) based on the Tibet III experiment in the northern hemisphere is not seriously biased. The best-fit amplitudes of the anisotropy, on the other hand, are only one third or less of those reported by the Tibet III experiment, indicating attenuation due to solar modulation. The rigidity dependence of the anisotropy amplitude in the sub-TeV region is consistent with the spectrum reported by Hall et al. (1999), smoothly extending to the Tibet III result in the multi-TeV region. The amplitude at higher energies appears almost constant or gradually decreasing with increasing rigidity.
我们分析了1985 - 2006年在日本Matsushiro (MAT)和1993 - 2005年在塔斯马尼亚Liapootah (LPT)观测到的恒星日变化。这些台站组成了位于日本和澳大利亚的地下μ子探测器的两半球网络(THN)。MAT和LPT的年平均谐波矢量基本稳定,与太阳活动周期或磁周期没有显著的相位和振幅变化。因此,本文分析了整个观测期的平均各向异性,即1985-2006年的MAT和1993-2005年的LPT。我们对THN数据采用了与Amenomori等人(2007)对西藏III数据采用的模型各向异性相同的最佳拟合分析。西藏三号实验记录的原始宇宙射线中位能量为~0.5 TeV和~5 TeV。结果表明,无论主粒子能量的数量级差异如何,最佳拟合各向异性的强度分布与西藏三号数据非常相似。这与THN观测结果一起证实了Amenomori等人(2007)基于北半球西藏三号试验的分析并没有严重偏差。另一方面,各向异性的最佳拟合幅度仅为西藏三号实验报告的三分之一或更少,表明由于太阳调制而衰减。亚tev区域各向异性振幅的刚性依赖性与Hall等(1999)报道的光谱一致,在多tev区域平滑地延伸到Tibet III结果。随着刚度的增加,高能量处的振幅几乎保持不变或逐渐减小。
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引用次数: 3
Dynamical masses for the nearest brown dwarf binary: ε Indi Ba, Bb 最近的褐矮星双星的动力质量:ε Indi Ba, Bb
Pub Date : 2008-11-04 DOI: 10.1063/1.3099160
C. Cardoso, M. McCaughrean, R. R. King, L. Close, R. Scholz, R. Lenzen, W. Brandner, N. Lodieu, H. Zinnecker
We present preliminary astrometric results for the closest known brown dwarf binary to the Sun: e Indi Ba, Bb at a distance of 3.626 pc. With ongoing monitoring of the relative separation of the two brown dwarfs (spectral types T1 and T6) with VLT NACO near‐IR adaptive optics system since June 2004, we obtain a model‐independent dynamical total mass for the system of 121 MJup, some 60% larger than the one obtained by McCaughrean et al., implying that the system may be as old as 5 Gyr. We have also been monitoring the absolute astrometric motions of the system using the VLTFORS2 optical imager since August 2005 to determine the individual masses. We predict a periastron passage in early 2010, by which time the system mass will be constrained to <1 MJup and we will be able to determine the individual masses accurately in a dynamical, model‐independent manner.
我们给出了已知距离太阳最近的褐矮星双星的初步天文测量结果:e Indi Ba, Bb,距离为3.626 pc。自2004年6月以来,利用VLT NACO近红外自适应光学系统对两颗褐矮星(光谱类型T1和T6)的相对分离进行了持续监测,我们获得了121 MJup系统的模型无关的动态总质量,比McCaughrean等人获得的质量大60%左右,这意味着该系统可能已有5 Gyr的历史。自2005年8月以来,我们也一直在使用VLTFORS2光学成像仪监测系统的绝对天文运动,以确定单个质量。我们预测在2010年初会有一次近天星穿越,届时系统的质量将被限制在< 1mjup,我们将能够以一种动力学的、与模型无关的方式准确地确定单个质量。
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引用次数: 5
The full spectrum Galactic terrarium: MHz to TeV observations of various critters 全光谱的银河玻璃容器:兆赫到TeV对各种生物的观察
Pub Date : 2008-11-04 DOI: 10.1063/1.3076673
M. Roberts, C. L. Brogan, S. Ransom, M. Lyutikov, E. Wilhelmi, A. Djannati-Ataï, R. Terrier, S. Dougherty, E. Grundstrom, J. Hessels, Simon Johnston, M. McSwain, P. Ray, K. Wood, G. G. Pooley, A. Weinstein
Multi-wavelength studies at radio, infrared, optical, X-ray, and TeV wavelengths have discovered probable counterparts to many Galactic sources of GeV emission detected by EGRET. These include pulsar wind nebulae, high mass X-ray binaries, and mixed morphology supernova remnants. Here we provide an overview of the observational properties of Galactic sources which emit across 19 orders of magnitude in energy. We also present new observations of several sources.
在射电、红外、光学、x射线和TeV波长的多波长研究中,已经发现了可能与EGRET探测到的许多GeV发射的银河系源相对应的物体。这些包括脉冲星风星云、高质量x射线双星和混合形态的超新星遗迹。在这里,我们提供了一个概览的观测性质银河源发射跨越19个数量级的能量。我们还提出了几个来源的新观察结果。
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引用次数: 3
Parameter Estimation from an Optimal Projection in a Local Environment 局部环境下最优投影的参数估计
Pub Date : 2008-11-03 DOI: 10.1063/1.3059083
A. Bijaoui, A. Recio-Blanco, P. Laverny
The parameter fit from a model grid is limited by our capability to reduce the number of models, taking into account the number of parameters and the non linear variation of the models with the parameters. The Local MultiLinear Regression (LMLR) algorithms allow one to fit linearly the data in a local environment. The MATISSE algorithm, developed in the context of the estimation of stellar parameters from the Gaia RVS spectra, is connected to this class of estimators. A two-steps procedure was introduced. A raw parameter estimation is first done in order to localize the parameter environment. The parameters are then estimated by projection on specific vectors computed for an optimal estimation. The MATISSE method is compared to the estimation using the objective analysis. In this framework, the kernel choice plays an important role. The environment needed for the parameter estimation can result from it. The determination of a first parameter set can be also avoided for this analysis. These procedures based on a local projection can be fruitfully applied to non linear parameter estimation if the number of data sets to be fitted is greater than the number of models.
考虑到参数的数量和模型随参数的非线性变化,模型网格的参数拟合受到我们减少模型数量的能力的限制。局部多元线性回归(LMLR)算法允许在局部环境中线性拟合数据。在根据盖亚RVS光谱估计恒星参数的背景下开发的MATISSE算法与这类估计器有关。介绍了一个两步法。首先进行原始参数估计,以便对参数环境进行局部化。然后通过在特定向量上的投影来估计参数,以获得最优估计。将马蒂斯方法与客观分析的估计方法进行了比较。在这个框架中,内核选择起着重要的作用。参数估计所需的环境可以由此产生。在此分析中还可以避免确定第一个参数集。当拟合的数据集数量大于模型数量时,这些基于局部投影的方法可以有效地应用于非线性参数估计。
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引用次数: 3
Doppler maps and surface differential rotation of EI Eri from the MUSICOS 1998 observations 来自MUSICOS 1998观测的EI Eri的多普勒图和地表自转差异
Pub Date : 2008-11-03 DOI: 10.1063/1.3099204
Zs. KHov'ari, A. Washuettl, B. Foing, K. Vida, J. Bartus, K. Ol'ah, the Musicos 98 team
We present time‐series Doppler images of the rapidly‐rotating active binary star EI Eri from spectroscopic observations collected during the MUSICOS multi‐site campaign in 1998, since the critical rotation period of 1.947 days makes it impossible to obtain time‐resolved images from a single site. From the surface reconstructions a weak solar‐type differential rotation, as well as a tiny poleward meridional flow are measured.
由于临界旋转周期为1.947天,因此不可能从单个地点获得时间分辨率的图像,因此我们展示了1998年MUSICOS多站点运动期间收集的快速旋转的活动双星EI Eri的时间序列多普勒图像。从表面重建中测量到微弱的太阳型微分旋转,以及微小的极向经向流动。
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引用次数: 1
Mass and Mean Velocity Dispersion Relations for Supermassive Black Holes in Galactic Bulges 星系凸起中超大质量黑洞的质量和平均速度色散关系
Pub Date : 2008-11-03 DOI: 10.22323/1.062.0110
Y. Lou, Yan-Fei Jiang
Growing evidence indicate supermassive black holes (SMBHs) in the mass range of $M_{rm BH}$$sim 10^6-10^{10}M_{odot}$ lurking in central bulges of many galaxies. Extensive observations reveal fairly tight power laws of $M_{rm BH}$ versus the mean stellar velocity dispersion $sigma$ of the host bulge. The dynamic evolution of a bulge and the formation of a central SMBH should be physically linked by various observational clues. In this contribution, we reproduce the empirical $M_{rm BH}-sigma$ power laws based on a self-similar general polytropic quasi-static bulge evolution and a sensible criterion of forming a SMBH surrounding the central density singularity of a general singular polytropic sphere (SPS) cite{loujiang2008}. Other properties of host bulges and central SMBHs are also examined. Based on our model, we discuss the intrinsic scatter of the $M_{rm BH}-sigma$ relation and a scenario for the evolution of SMBHs in different host bulges.
越来越多的证据表明,超大质量黑洞(SMBHs)的质量范围为$M_{rm BH}$$sim 10^6-10^{10}M_{odot}$,潜伏在许多星系的中心凸起处。广泛的观测揭示了$M_{rm BH}$相对于主凸起的平均恒星速度色散$sigma$的相当紧密的幂律。凸起的动态演化和中心大黑洞的形成应该通过各种观测线索在物理上联系起来。在这篇贡献中,我们基于自相似的一般多向准静态凸起演化和在一般奇异多向球体(SPS)的中心密度奇点周围形成SMBH的合理准则再现了经验$M_{rm BH}-sigma$幂律cite{loujiang2008}。本文还研究了宿主凸起和中心SMBHs的其他性质。基于我们的模型,我们讨论了$M_{rm BH}-sigma$关系的本然散点,以及SMBHs在不同宿主凸起中演化的情景。
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引用次数: 0
Science with the World Space Observatory - Ultraviolet 科学与世界空间天文台-紫外线
Pub Date : 2008-11-03 DOI: 10.1007/978-0-387-87621-4_42
A. Castro, I. Pagano, M. Sachkov, A. Lecavelier, G. Piotto, R. González, B. Shustov
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引用次数: 33
Massive star formation in Wolf-Rayet galaxies: I. Optical and NIR photometric results Wolf-Rayet星系中大质量恒星的形成:1 .光学和近红外光度测量结果
Pub Date : 2008-11-01 DOI: 10.1051/0004-6361:200809409
Á. López-Sánchez, C. Esteban
(Abridged) We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show the presence of a substantial population of massive stars. The main aims are the study of the massive star formation and stellar populations in these galaxies, and the role that interactions with or between dwarf galaxies and/or low surface companion objects have in triggering the bursts. We completed new deep optical and NIR broad-band images, as well as the new continuum-subtracted H$alpha$ maps, of our sample of Wolf-Rayet galaxies. We analyze the morphology of each system and its surroundings and quantify the photometric properties of all important objects. All data were corrected for both extinction and nebular emission using our spectroscopic data. The age of the most recent star-formation burst is estimated and compared with the age of the underlying older low-luminosity population. The Ha-based star-formation rate, number of O7V equivalent stars, mass of ionized gas, and mass of the ionizing star cluster are also derived. We found interaction features in many (15 up to 20) of the analyzed objects, which were extremely evident in the majority. We checked that the correction for nebular emission to the broad-band filter fluxes is important in compact objects and/or with intense nebular emission to obtain realistic colors and compare with the predictions of evolutionary synthesis models. The estimate of the age of the most recent star-formation burst is derived consistently. With respect to the results found in individual objects, we remark the strong Ha emission found in IRAS 08208+2816, UM 420, and SBS 0948+532, the detection of a double-nucleus in SBS 0926+606A, a possible galactic wind in Tol 9, and one (two?) nearby dwarf star-forming galaxies surrounding Tol 1457-437.
(节选)我们对20个星暴星系的样本进行了全面的多波长分析,这些星系显示了大量大质量恒星的存在。主要目的是研究这些星系中的大质量恒星形成和恒星种群,以及与矮星系和/或低表面伴星之间的相互作用在触发爆发中的作用。我们完成了Wolf-Rayet星系样本的新的深光学和近红外宽带图像,以及新的连续减去H$alpha$图。我们分析了每个系统及其周围环境的形态,并量化了所有重要物体的光度特性。所有的数据都校正了消光和星云发射使用我们的光谱数据。估计了最近恒星形成爆发的年龄,并将其与潜在的较老的低光度星系群的年龄进行了比较。我们还推导出了基于ha的恒星形成速率、O7V等效恒星的数量、电离气体的质量和电离星团的质量。我们在许多(15到20个)分析对象中发现了交互特性,这在大多数情况下是非常明显的。我们检查了星云发射对宽带滤光片通量的校正在致密物体和/或具有强烈星云发射的情况下是重要的,以获得真实的颜色,并与进化综合模型的预测相比较。最近的恒星形成爆发的年龄估计是一致的。对于单个天体的观测结果,我们注意到在IRAS 08208+2816、UM 420和SBS 0948+532中发现了强烈的Ha辐射,在SBS 0926+606A中发现了一个双核,在Tol 9中发现了一个可能的星系风,以及在Tol 1457-437周围有一个(两个)附近的矮星形成星系。
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引用次数: 40
Supergiant Fast X-ray Transients: interpretation of archival INTEGRAL data 超巨星快速x射线瞬变:档案积分数据的解释
Pub Date : 2008-10-30 DOI: 10.22323/1.067.0086
L. Ducci, L. Sidoli, A. Paizis, S. M. U. D. S. dell'Insubria, Como INAF-IASF Milano, Italy.
INTEGRAL monitoring of the Galactic Plane in the last 5 years revealed a new subclass of High Mass X-ray Binaries (HMXBs), the Supergiant Fast X-ray Transients (SFXTs). They display flares lasting from minutes to hours, with peak luminosity of 1E36-1E37 erg/s and a frequent long term flaring activity reaching an X-ray luminosity of 1E33-1E34 erg/s, as recently detected by the Swift satellite. The quiescent level is around 1E32 erg/s. We performed a systematic re-analysis of archival INTEGRAL data of four SFXTs: IGRJ16479-4514, XTEJ1739-302, IGRJ17544-2619, IGRJ18410-0535. This led to the discovery of previously unnoticed outbursts from IGRJ16479-4514 and IGRJ17544-2619. We discuss these results in the framework of the different structure of the supergiant wind proposed to explain the outburst from this new class of sources.
近5年来对银道面的整体监测揭示了高质量x射线双星(hmxb)的一个新亚类,超巨星快速x射线瞬变(SFXTs)。它们的耀斑持续时间从几分钟到几小时不等,峰值亮度为1E36-1E37 erg/s,而频繁的长期耀斑活动达到了1E33-1E34 erg/s的x射线亮度,这是雨燕卫星最近探测到的。静止水平约为1e32erg /s。对IGRJ16479-4514、XTEJ1739-302、IGRJ17544-2619、IGRJ18410-0535 4个SFXTs的档案积分数据进行系统再分析。这导致了之前未被注意到的IGRJ16479-4514和IGRJ17544-2619爆发的发现。我们在不同结构的超巨型风的框架内讨论这些结果,以解释这类新来源的爆发。
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引用次数: 2
期刊
arXiv: Astrophysics
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