arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1408.4115astro-ph.HEastro-ph.COastro-ph.GAhep-ph
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堆积星系光谱中未检测到无菌中微子的X射线发射

Non-Detection of X-Ray Emission From Sterile Neutrinos in Stacked Galaxy Spectra

Michael E. Anderson, Eugene Churazov, Joel N. Bregman

摘要:

我们进行了一个全面的搜索X射线发射线从不育中微子暗物质,最近声称的不明发射线的叠加X射线光谱的星系团和银河系和M31的中心。由于声称的发射线位于3.5 keV左右,我们专注于星系和星系群(掩盖了中心区域),因为这些物体发出的辐射非常少,高于$\sim 2$ keV,并提供了一个干净的背景,以检测发射线。我们开发了一种形式主义,最大限度地提高信号噪声衰减的暗物质发射线的加权每个X射线事件根据预期的暗物质配置文件。总共,我们检查81和89星系钱德拉和XMM-牛顿分别,总计15.0和14.6毫秒的积分时间。我们没有发现任何发射谱线的重要证据,这对质量在4.8-12.4 keV之间的不育中微子的混合角有很强的限制。特别是,如果Bulbul等人(2014)的3.57 keV特征是由于7.1 keV无菌中微子发射造成的,我们将在我们的两个样本中的$4.4σ$和$11.8σ$处检测到它。系统不确定性的最保守估计将这些约束减少到$4.4σ$和7.8 $σ$,或者让线能量在3.50和3.60 keV之间变化将这些约束分别减少到$2.7σ$和$11.0σ$。与以前的限制,我们的测量不依赖于模型的X射线背景或假设的对数斜率的中心的暗物质配置文件。

英文摘要:

We conduct a comprehensive search for X-ray emission lines from sterile neutrino dark matter, motivated by recent claims of unidentified emission lines in the stacked X-ray spectra of galaxy clusters and the centers of the Milky Way and M31. Since the claimed emission lines lie around 3.5 keV, we focus on galaxies and galaxy groups (masking the central regions), since these objects emit very little radiation above $\sim 2$ keV and offer a clean background against which to detect emission lines. We develop a formalism for maximizing the signal-to-noise of decaying dark matter emission lines by weighing each X-ray event according to the expected dark matter profile. In total, we examine 81 and 89 galaxies with Chandra and XMM-Newton respectively, totaling 15.0 and 14.6 Ms of integration time. We find no significant evidence of any emission lines, placing strong constraints on the mixing angle of sterile neutrinos with masses between 4.8-12.4 keV. In particular, if the 3.57 keV feature from Bulbul et al. (2014) were due to 7.1 keV sterile neutrino emission, we would have detected it at $4.4σ$ and $11.8σ$ in our two samples. The most conservative estimates of the systematic uncertainties reduce these constraints to $4.4σ$ and 7.8$σ$, or letting the line energy vary between 3.50 and 3.60 keV reduces these constraints to $2.7σ$ and $11.0σ$ respectively. Unlike previous constraints, our measurements do not depend on the model of the X-ray background or on the assumed logarithmic slope of the center of the dark matter profile.

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