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arXiv 0801.2086astro-ph
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软γ射线中的INTEGRAL SPI全天视图:点源和银河弥散辐射的研究

INTEGRAL SPI All-Sky View in Soft Gamma Rays: Study of Point Source and Galactic Diffuse Emissions

L. Bouchet, E. Jourdain, J. P. Roques, A. Strong, R. Diehl, F. Lebrun, R. Terrier

摘要:

我们已经处理的数据积累与积分SPI在4年(~ 51毫秒)研究银河系的“扩散”的发射形态在20千电子伏至8兆电子伏的能量范围。为了实现这一目标,我们同时得出了一个全天普查的发射源和图像的银河脊(GR)的排放。在中心弧度范围内,在25-50、50-100和100-300 keV区域,分辨点源辐射分别占总辐射的88%、91%和68%。我们比较了GR排放的空间分布,从CO和NIR地图,并量化我们的结果,通过纬度和经度配置文件。低于50千电子伏,SPI数据更好地跟踪后者,支持恒星起源的这种排放。此外,我们发现GR发射光谱遵循幂律,在高于50 keV时光子指数约为1.55,而在低于该能量时需要额外的组分。这一部分显示了30 keV左右的截止值,加强了Krivonos等人(2007年)提出的恒星起源。湮灭扩散发射分量提取的同时,导致相关参数(正电子素通量和分数)的测定。一个具体的讨论是专门的湮灭线分布,因为一个显着的发射被检测到超过一个区域大到~80度的~10度可能与磁盘或晕周围的中心区域,我们的银河系。

英文摘要:

We have processed the data accumulated with INTEGRAL SPI during 4 years (~ 51 Ms) to study the Galactic ``diffuse'' emission morphology in the 20 keV to 8 MeV energy range. To achieve this objective, we have derived simultaneously an all-sky census of emitting sources and images of the Galactic Ridge (GR) emission. In the central radian, the resolved point source emission amounts to 88%, 91% and 68% of the total emission in the 25-50, 50-100 and 100-300 keV domains respectively. We have compared the GR emission spatial distribution to those obtained from CO and NIR maps, and quantified our results through latitude and longitude profiles. Below 50 keV, the SPI data are better traced by the latter, supporting a stellar origin for this emission. Furthermore, we found that the GR emission spectrum follows a power law with a photon index ~ 1.55 above 50 keV while an additional component is required below this energy. This component shows a cutoff around 30 keV, reinforcing a stellar origin, as proposed by Krivonos et al. (2007). The annihilation diffuse emission component is extracted simultaneously, leading to the determination of the related parameters (positronium flux and fraction). A specific discussion is devoted to the annihilation line distribution since a significant emission is detected over a region as large as ~80 degrees by ~10 degrees potentially associated with the disk or halo surrounding the central regions of our Galaxy.

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