Emission-rotation correlation in pulsars: new discoveries with optimal techniques
Emission-rotation correlation in pulsars: new discoveries with optimal techniques
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DOI：
10.1093/mnras/stv2715
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发表时间：
2015-11
影响因子：
4.8
通讯作者：
P. Brook;P. Brook;A. Karastergiou;A. Karastergiou;A. Karastergiou;S. Johnston;M. Kerr;R. Shannon;S. Roberts
中科院分区：
文献类型：
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作者：
P. Brook;P. Brook;A. Karastergiou;A. Karastergiou;A. Karastergiou;S. Johnston;M. Kerr;R. Shannon;S. Roberts
已知脉冲星显示短期变化。最近，已经出现了长期发射变化的例子，这些变化通常与脉冲星旋转特性的变化有关。为了进一步阐明这种关系，我们已经开发了技术来识别脉冲星数据中的发射和旋转变化，并确定两者之间的相关性。单独的观察可能太嘈杂，无法识别脉搏轮廓中的细微变化。我们使用高斯过程（GP）回归模型噪声观测和脉冲轮廓变异性产生一个连续的地图。通常，需要多个观测历元来获得脉冲星的自旋频率导数（ν）。因此，GP回归也被用来获得ν，假设脉冲星定时噪声主要是由ν的未建模变化引起的。我们的技术区分两种类型的变化：总通量密度的变化与脉冲形状的变化。我们将这些技术应用于Parkes射电望远镜观测到的168颗双星，发现虽然通量密度的变化是普遍存在的，但脉冲轮廓形状的实质性变化是罕见的，我们重现了以前发表的结果，并给出了7颗双星轮廓形状变化的例子;特别地，在PSR J1602-5100中发现了轮廓形状和旋转的相关变化的清楚的新示例。在形状变化的双态模型中，出现了比先前提出的两态模型更复杂的图像。我们的结论是，我们的简单假设，所有的定时噪声可以解释为ν变异性是不足以解释我们的数据集。
Pulsars are known to display short-term variability. Recently, examples of longer term emission variability have emerged that are often correlated with changes in the rotational properties of the pulsar. To further illuminate this relationship, we have developed techniques to identify emission and rotation variability in pulsar data, and determine correlations between the two. Individual observations may be too noisy to identify subtle changes in the pulse profile. We use Gaussian process (GP) regression to model noisy observations and produce a continuous map of pulse profile variability. Generally, multiple observing epochs are required to obtain the pulsar spin frequency derivative (ν). GP regression is, therefore, also used to obtain ν, under the hypothesis that pulsar timing noise is primarily caused by unmodelled changes in ν. Our techniques distinguish between two types of variability: changes in the total flux density versus changes in the pulse shape. We have applied these techniques to 168 pulsars observed by the Parkes radio telescope, and see that although variations in flux density are ubiquitous, substantial changes in the shape of the pulse profile are rare.We reproduce previously published results and present examples of profile shape changing in seven pulsars; in particular, a clear new example of correlated changes in profile shape and rotation is found in PSR J1602-5100. In the shape changing pulsars, a more complex picture than the previously proposed two state model emerges. We conclude that our simple assumption that all timing noise can be interpreted as ν variability is insufficient to explain our data set.