Observations by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite have identified an excess of microwave emission from the centre of the Milky Way. It has been suggested that this WMAP haze emission could potentially be synchrotron emission from relativistic electrons and positrons produced in the annihilations of one (or more) species of dark matter particles. In this paper we re-calculate the intensity and morphology of the WMAP haze using a multi-linear regression involving full-sky templates of the dominant forms of galactic foreground emission, using two different CMB sky signal estimators. The first estimator is a posterior mean CMB map, marginalized over a general foreground model using a Gibbs sampling technique, and the other is the ILC map produced by the WMAP team. Earlier analyses of the WMAP haze used the ILC map, which is more contaminated by galactic foregrounds than the Gibbs map. In either case, we re-confirm earlier results that a statistically significant residual emission remains after foreground subtraction that is concentrated around the galactic centre. However, we find that the significance of this emission can be significantly reduced by allowing for a subtle spatial variation in the frequency dependence of soft synchrotron emission in the inner and outer parts of the galaxy. We also re-investigate the prospect of a neutralino dark matter interpretation of the origin of the haze, and find that significant boosting in the dark matter annihilation rate is required, relative to that obtained with a smooth galactic dark matter distribution, in order to reproduce the inferred residual emission, contrary to that deduced in several recent studies.
Systematic Effects in Extracting a "Gamma-Ray Haze" from Spatial Templates
最近的说法是，费米大天区望远镜（Fermi Large Area Telescope）探测到的弥漫星系辐射中存在伽马射线过量，其形态类似于WMAP的薄雾，这是基于这样的假设：星际介质（ISM）柱密度和408 MHz天空的空间模板分别是中性π介子和逆康普顿（IC）伽马射线辐射的良好代理。我们确定了显着的系统性影响，在这个过程中，可以人为地诱导一个额外的扩散组件的形态惊人地相似，声称的伽马射线雾。为了定量地说明这一点，我们计算的伽马射线发射的比例从中性π介子的ISM柱密度，和IC同步辐射的天空地图，使用详细的银河宇宙射线模型和模拟。在银河系中心的上方和下方区域，ISM模板低估了中性π介子衰变产生的伽马射线辐射约20%。此外，同步加速器模板往往低估了低能量（几个GeV）的IC发射，并高估了它在更高的能量（几十个GeV）的潜在大的因素，关键取决于假设的银河系磁场结构。我们发现的系统效应的大小与声称的“费米雾”信号的大小相当。因此，我们的结论是，一个详细的模型，银河漫发射是必要的，以最终评估可能与WMAP霾形态的伽马射线过量的存在。
The Fermi Bubbles: Giant, Multi-Billion-Year-Old Reservoirs of Galactic Center Cosmic Rays
最近，费米-LAT仪器观测到的伽马射线天空中出现了巨大特征的证据：以银河系核心为中心的双边发射“气泡”，并在银河系平面上方和下方延伸到约10千秒差距。这些结构与WMAP数据中发现的非热微波“薄雾”和ROSAT探测到的X射线辐射的扩展区域相吻合。气泡的伽马射线辐射的特征是具有坚硬且相对均匀的光谱，相对均匀的强度，总光度约为4 x 10^37 erg/s，比它们的微波光度大约大一个数量级，而比它们的X射线光度小一个数量级以上。在这里，我们表明，气泡是自然的解释，由于人口的遗迹宇宙射线质子和较重的离子注入的过程与极长的时间尺度（>~8 Gyr）和高面密度的恒星形成在银河系中心。
