Reduced order modelling in searches for continuous gravitational waves - I. Barycentring time delays
Reduced order modelling in searches for continuous gravitational waves - I. Barycentring time delays
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寻找连续引力波的降阶建模 - I. 重心时间延迟
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
K. Wette
中科院分区：
文献类型：
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作者：
M. Pitkin;S. Doolan;L. McMenamin;K. Wette
在地球上的观测者测量到的太阳外源发射的频率和相位是由观测者相对于源的运动和相对论效应调制的。这些调制主要取决于源的天空位置。在长时间的观测中，例如脉冲星计时，或寻找连续的引力波，需要精确的调制知识来一致地跟踪源的相位。调制可以建模为天空位置和时间相关的时间延迟，将到达观测者的时间转换为源的惯性坐标系，源通常可以是太阳系的质心（SSB）。我们研究了使用降阶模型来加速任何天空位置的时间延迟计算。我们发现时间延迟模型可以分解为四个基向量，并且可以用这些基向量重建任何天空位置的延迟到亚纳秒精度。与引力波搜索中时间延迟计算的标准例程相比，使用简化基可以使速度提高30倍。我们还研究了二元系统中源的时滞分量。假设偏心率<0.25，我们可以重建到100纳秒以内的延迟，最好的情况是10倍的加速，或者当插值不同轨道周期或时间戳的基础时，加速是2倍的。在对具有天空位置不确定性或二元参数不确定性的源进行长时间相参搜索时，这些加速可以在不增加大量额外计算负担的情况下增强其范围。
The frequencies and phases of emission from extra-solar sources measured by Earth-bound observers are modulated by the motions of the observer with respect to the source, and through relativistic effects. These modulations depend critically on the source’s sky-location. Precise knowledge of the modulations are required to coherently track the source’s phase over long observations, for example, in pulsar timing, or searches for continuous gravitational waves. The modulations can be modelled as sky-location and time dependent time delays that convert arrival times at the observer to the inertial frame of the source, which can often be the solar system barycentre (SSB). We study the use of Reduced Order Modelling for speeding up the calculation of this time delay for any sky-location. We find that the time delay model can be decomposed into just four basis vectors, and with these the delay for any sky-location can be reconstructed to sub-nanosecond accuracy. When compared to standard routines for time delay calculation in gravitational wave searches, using the reduced basis can lead to speed-ups of 30 times. We have also studied components of time delays for sources in binary systems. Assuming eccentricities <0.25 we can reconstruct the delays to within 100s of nanoseconds, with best case speed-ups of a factor of 10, or factors of two when interpolating the basis for different orbital periods or time stamps. In long-duration phase-coherent searches for sources with sky-position uncertainties, or binary parameter uncertainties, these speed-ups could allow enhancements in their scopes without large additional computational burdens.