GAMMA-RAY EMISSION FROM THE GLOBULAR CLUSTERS LILLER 1, M80, NGC 6139, NGC 6541, NGC 6624, AND NGC 6752
GAMMA-RAY EMISSION FROM THE GLOBULAR CLUSTERS LILLER 1, M80, NGC 6139, NGC 6541, NGC 6624, AND NGC 6752
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DOI：
10.1088/0004-637x/729/2/90
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
P. Tam;A. Kong;C. Hui;K. Cheng;C. Li;T. Lu
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文献类型：
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作者：
P. Tam;A. Kong;C. Hui;K. Cheng;C. Li;T. Lu
多亏了费米伽马射线太空望远镜获得的数据，球状星团(GC)正在成为一种新的γ射线发射体。到目前为止，已知有8个GC发射能量为100 MeV的γ射线。基于GC的恒星相遇率，我们从所有已知的GC中找出了潜在的γ射线发射GC，这些GC以前没有被详细研究过。在本文中，我们发现了一些新的γ射线GC：Liller1，NGC6624和NGC6752，以及M80，NGC6139和NGC6541的γ射线发射的证据，其中在GC潮汐半径内发现了γ射线。作为银河系中金属丰度最高的GC之一，Liller1的γ-射线光度也是所有已知γ-射线GC中最高的。此外，我们证实了先前关于NGC6441附近有一个重要的γ射线发射区的报道。我们简要地讨论了一些GC岩心观测到的γ射线的偏移量。在距离γ10kpc的距离上不断增加的已知∼射线GC的数量对于我们理解γ射线发射机制以及为GC潜在的毫秒脉冲星群提供了一个替代的探测器是很重要的。
Globular clusters (GCs) are emerging as a new class of γ-ray emitters, thanks to the data obtained from the Fermi Gamma-ray Space Telescope. By now, eight GCs are known to emit γ-rays at energies >100 MeV. Based on the stellar encounter rate of the GCs, we identify potential γ-ray emitting GCs out of all known GCs that have not been studied in detail before. In this paper, we report the discovery of a number of new γ-ray GCs: Liller 1, NGC 6624, and NGC 6752, and evidence of γ-ray emission from M80, NGC 6139, and NGC 6541, in which γ-rays were found within the GC tidal radius. With one of the highest metallicities among all GCs in the Milky Way, the γ-ray luminosity of Liller 1 is found to be the highest of all known γ-ray GCs. In addition, we confirm a previous report of a significant γ-ray emitting region next to NGC 6441. We briefly discuss the observed offset of γ-rays from some GC cores. The increasing number of known γ-ray GCs at distances out to ∼10 kpc is important for us to understand the γ-ray emitting mechanism and provides an alternative probe to the underlying millisecond pulsar populations of the GCs.