arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1302.7173astro-ph.HE
收藏

证据的第二个组成部分,在高能量的核心排放从半人马座A?

Evidence for a second component in the high-energy core emission from Centaurus A?

N. Sahakyan, R. Yang, F. A. Aharonian, F. M. Rieger

摘要:

本文报道了对邻近射电星系半人马座A(Cen A)四年观测的\fermi数据的分析。增加的光子统计导致从Cen A的核心探测到高达50 GeV的高能($>\:100$ MeV)$γ$射线,探测显著性约为44 $σ$。核心的平均伽马射线光谱揭示了可能偏离简单幂律的证据。一个可能性分析与打破幂律模型表明,光子指数变得更硬以上$E_b \simeq 4$ GeV,从$Γ_1=2.74\pm0.03$以下的$Γ_2=2.09\pm0.20$以上。这种硬化可能是由一个额外的高能量成分的贡献超出了常见的同步加速器自康普顿喷流排放。采用15天、30天和60天分组的光变曲线变异性分析未提供任何组分变异性的证据。在45天的时间尺度上发现了观测到的通量的可能变化的迹象,但统计数据不允许我们在这方面做出明确的结论。我们将我们的结果与H.E.S.S.在TeV的能量范围内,并讨论观察到的硬化可能的起源。

英文摘要:

We report on an analysis of \fermi data from four year of observations of the nearby radio galaxy Centaurus A (Cen A). The increased photon statistics results in a detection of high-energy ($>\:100$ MeV) $γ$-rays up to 50 GeV from the core of Cen A, with a detection significance of about 44$σ$. The average gamma-ray spectrum of the core reveals evidence for a possible deviation from a simple power-law. A likelihood analysis with a broken power-law model shows that the photon index becomes harder above $E_b \simeq 4$ GeV, changing from $Γ_1=2.74\pm0.03$ below to $Γ_2=2.09\pm0.20$ above. This hardening could be caused by the contribution of an additional high-energy component beyond the common synchrotron-self Compton jet emission. A variability analysis of the light curve with 15-, 30-, and 60-day bins does not provide evidence for variability for any of the components. Indications for a possible variability of the observed flux are found on 45-day time scale, but the statistics do not allow us to make a definite conclusion in this regards. We compare our results with the spectrum reported by H.E.S.S. in the TeV energy range and discuss possible origins for the hardening observed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑