论文标题

搜索随机重力波背景和星系数计数之间的互相关

Searching for Cross-Correlation Between Stochastic Gravitational Wave Background and Galaxy Number Counts

论文作者

Yang, Kate Ziyan, Mandic, Vuk, Scarlata, Claudia, Banagiri, Sharan

论文摘要

Advanced Ligo和Advanced处女座最近根据其第一和第二观测运行(O1和O2)的数据,发布了持续定向随机引力背景(SGWB)的上限测量。在本文中,我们研究了这种最大的可能性SGWB图与宇宙中物质结构的电磁示踪剂(例如星系数计数)之间是否存在相关性。我们开发的方法将提高对SGWB中各向异性的未来搜索的敏感性,并扩展SGWB各向异性的使用以探测宇宙中结构的形成。为了计算互相关,我们在多个频带中使用了SGWB的球形谐波分解,并将其转换为基于像素的天空图。对于电磁(EM)部分,我们使用Sloan Digital Sky Survey(SDSS)星系目录,并形成星系数的HealPix Sky Maps,以与SGWB地图相同的角度分辨率计数。我们计算这些SGWB和Galaxy计数图之间的基于像素的连贯性。在不同的SGWB频带和不同的Galaxy红移箱中评估了我们的结果后,我们得出结论,SGWB和Galaxy数量计数映射之间的相干性由SGWB映射中的零测量噪声主导,因此并不统计上很重要。我们预计,通过基于高级LIGO和高级处女座的第三次观察运行(O3),使用更敏感的SGWB测量值,可以显着改善该分析的结果。

Advanced LIGO and Advanced Virgo have recently published the upper limit measurement of persistent directional stochastic gravitational wave background (SGWB) based on data from their first and second observing runs (O1 and O2). In this paper we investigate whether a correlation exists between this maximal likelihood SGWB map and the electromagnetic tracers of matter structure in the universe, such as galaxy number counts. The method we develop will improve the sensitivity of future searches for anisotropy in the SGWB and expand the use of SGWB anisotropy to probe the formation of structure in the universe. In order to compute the cross-correlation, we used the spherical harmonic decomposition of SGWB in multiple frequency bands and converted them into pixel-based sky maps in HEALPix basis. For the electromagnetic (EM) part, we use the Sloan Digital Sky Survey (SDSS) galaxy catalog and form HEALPix sky maps of galaxy number counts at the same angular resolution as the SGWB maps. We compute the pixel-based coherence between these SGWB and galaxy count maps. After evaluating our results in different SGWB frequency bands and in different galaxy redshift bins, we conclude that the coherence between the SGWB and galaxy number count maps is dominated by the null measurement noise in the SGWB maps, and therefore not statistically significant. We expect the results of this analysis to be significantly improved by using the more sensitive upcoming SGWB measurements based on the third observing run (O3) of Advanced LIGO and Advanced Virgo.

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