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arXiv 1302.2114astro-ph.CO
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在普朗克早期释放致密源目录中河外射电源的长期变率

Long-term variability of extragalactic radio sources in the Planck Early Release Compact Source Catalogue

X. Chen, J. P. Rachen, M. Lopez-Caniego, C. Dickinson, T. J. Pearson, L. Fuhrmann, T. P. Krichbaum, B. Partridge

摘要:

结合使用威尔金森微波各向异性探测器(WMAP)从2001年至2008年的测量与普朗克从2009年至2010年的测量,我们调查的长期流量密度变化的河外射电源从普朗克早期发布紧凑源目录。单年单频WMAP图用于估计WMAP四个波段(Ka(33 GHz)、Q(41 GHz)、V(61 GHz)和W(94 GHz))中源的年平均通量密度。我们确定82,67,32,和15个来源分别为变量在大于99%的置信水平,在这四个波段。波段之间的变化幅度相当,并且与源的通量密度或光谱指数无关。WMAP Ka波段源的计数是稳定的,从一年到一年,尽管个别源的变化引起的波动。我们的大多数来源显示出波段之间的变化性具有很强的相关性。几乎所有显示出变异性的源都是耀变体。我们试图拟合两个简单的,四参数模型的时间序列的32个源显示相关的变化在多个频率-一个长期的耀斑模型和一个喷流模型。我们发现,19个源(60%)可以用简单的燃烧喷流模型拟合,其中10个也符合简单的长期燃烧模型。其余13个来源(40%)显示出更复杂的变异行为,这与任何一种模型都不一致。在我们的样本中,扩展的射电星系没有显示出任何变化的迹象,正如预期的那样,除了Pictor A,我们报告了2002年至2010年持续的毫米级耀斑的证据。

英文摘要:

Combining measurements taken using the Wilkinson Microwave Anisotropy Probe (WMAP) from 2001 to 2008 with measurements taken using Planck from 2009 to 2010, we investigate the long-term flux density variability of extragalactic radio sources selected from the Planck Early Release Compact Source Catalogue. The single-year, single-frequency WMAP maps are used to estimate yearly-averaged flux densities of the sources in the four WMAP bands: Ka (33 GHz), Q (41 GHz), V (61 GHz), and W (94 GHz). We identify 82, 67, 32, and 15 sources respectively as variable at greater than 99% confidence level in these four bands. The amplitudes of variation are comparable between bands, and are not correlated with either the flux densities or the spectral indices of the sources. The number counts of WMAP Ka-band sources are stable from year to year despite the fluctuation caused by individual source variability. Most of our sources show strong correlation in variability between bands. Almost all the sources that show variability are blazars. We have attempted to fit two simple, four-parameter models to the time-series of 32 sources showing correlated variability at multiple frequencies - a long-term flaring model and a rotating-jet model. We find that 19 sources (60%) can be fit with the simple rotating-jet model, and ten of these also fit the simple long-term flaring model. The remaining 13 sources (40%) show more complex variability behaviour that is not consistent with either model. Extended radio galaxies in our sample show no sign of variability, as expected, with the exception of Pictor A for which we report evidence for a millimetre flare lasting between 2002 and 2010.

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