Measurement of the anisotropy power spectrum of the radio synchrotron background
Measurement of the anisotropy power spectrum of the radio synchrotron background
复制标题
射电同步加速器背景各向异性功率谱的测量
DOI：
10.1093/mnras/stab2865
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发表时间：
2021
影响因子：
4.8
通讯作者：
Lucero, D M
中科院分区：
文献类型：
--
作者：
Offringa, A R;Singal, J;Heston, S;Horiuchi, S;Lucero, D M
我们提出了无线电同步加速器背景各向异性功率谱的第一个目标测量，在140 MHz，其中它是压倒性的主导光子背景。这一测量对于理解射电天空亮度的背景水平是很重要的，它主要是由频率低于ν ~ 0.5 GHz的陡谱同步辐射控制的，并且已经被测量到明显高于已知类别的河外源和大多数星系晕发射模型产生的亮度。我们通过低频阵列对两个18°场的观测确定了各向异性功率谱，范围从2°到0.2 arcmin，其中一个集中在北半球最冷的射电天空中，银河系的贡献最小，另一个与该位置偏移15°。我们发现，该各向异性功率比通量大于100Jy的点源的分布要高。这种水平的射电各向异性功率表明，如果它是由点源产生的，那么这些点源很可能是低通量的，而且数量多得令人难以置信，而且很可能以特定的方式聚集在一起。
We present the first targeted measurement of the power spectrum of anisotropies of the radio synchrotron background, at 140 MHz, where it is the overwhelmingly dominant photon background. This measurement is important for understanding the background level of radio sky brightness, which is dominated by steep-spectrum synchrotron radiation at frequencies belowν∼ 0.5 GHz and has been measured to be significantly higher than that produced by known classes of extragalactic sources and most models of Galactic halo emission. We determine the anisotropy power spectrum on scales ranging from 2° to 0.2 arcmin with Low-Frequency Array observations of two 18-deg2fields – one centred on the Northern hemisphere’s coldest patch of radio sky where the Galactic contribution is smallest and the other offset from that location by 15°. We find that the anisotropy power is higher than that attributable to the distribution of point sources above 100Jy in flux. This level of radio anisotropy power indicates that if it results from point sources, those sources are likely at low fluxes and incredibly numerous, and likely clustered in a specific manner.