[论文解读] Prospects for Localization of Gravitational Wave Transients by the Advanced LIGO and Advanced Virgo Observatories

J. Aasi, J. Abadie+96 more|arXiv (Cornell University)|Apr 2, 2013

Pulsars and Gravitational Waves Research被引用 43

一句话总结

本文评估了在未来十年内，利用先进LIGO与先进Virgo探测器网络对引力波暂现信号（特别是双中子星并合）进行本地化的前景。研究发现，若拥有三个或更多灵敏度相近、带宽广泛的探测器（包括潜在的印度LIGO站点），可将信号定位至几平方度范围内，从而实现多信使天文学中高效的后续观测。

ABSTRACT

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. For concreteness, we focus primarily on gravitational-wave signals from the inspiral of binary neutron star (BNS) systems, as the source considered likely to be the most common for detection and also promising for multimessenger astronomy. We find that confident detections will likely require at least 2 detectors operating with BNS sensitive ranges of at least 100 Mpc, while ranges approaching 200 Mpc should give at least ~1 BNS detection per year even under pessimistic predictions of signal rates. The ability to localize the source of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and can be as large as thousands of square degrees with only 2 sensitive detectors operating. Determining the sky position of a significant fraction of detected signals to areas of 5 sq deg to 20 sq deg will require at least 3 detectors of sensitivity within a factor of ~2 of each other and with a broad frequency bandwidth. Should one of the LIGO detectors be relocated in India as expected, many gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

研究动机与目标

• 为天文界提供未来十年内先进LIGO与先进Virgo探测器网络的现实观测情景，以支持多信使天文学。
• 量化探测器网络对暂现引力波信号（尤其是双中子星BNS系统）的敏感度。
• 评估探测器网络对引力波源天球位置本地化的精确度提升能力。
• 确定实现双中子星信号可靠探测与有效本地化所需的最低探测器配置与灵敏度。

提出的方法

• 建模先进LIGO与先进Virgo网络对暂现引力波信号（聚焦于双中子星BNS并合）的预期灵敏度。
• 通过模拟信号注入，分析探测器几何布局与相对灵敏度对天区本地化精度的影响。
• 评估不同网络配置下的本地化性能，包括双探测器与三探测器配置。
• 评估在印度增设LIGO探测器对提升本地化性能的影响，特别是改善基线分布的作用。
• 采用基于本地化区域立体角的指标来量化本地化性能。
• 在乐观与悲观的BNS事件率假设下比较本地化性能，以确定探测与本地化的阈值。

实验结果

研究问题

• RQ1 两个探测器需要达到多大的BNS敏感距离，才能实现引力波信号的可信探测？
• RQ2 探测器的数量与配置如何影响引力波暂现信号的天区本地化精度？
• RQ3 需要何种探测器灵敏度与地理分布，才能使至少50%的探测信号本地化至5至20平方度范围内？
• RQ4 在印度增设LIGO探测器将如何提升引力波信号的本地化能力？
• RQ5 在保守的BNS事件率估计下，预期每年可探测到多少次双中子星信号？

主要发现

• 要实现对双中子星（BNS）信号的可信探测，至少需要两个探测器，且其BNS敏感距离需达到100 Mpc以上。
• 当BNS敏感距离接近200 Mpc时，即使在悲观的信号率预测下，网络每年仍可实现至少一次BNS探测。
• 仅依靠两个灵敏探测器时，天区本地化范围可能高达数千平方度，严重限制后续观测效率。
• 要将显著比例的信号本地化至5至20平方度范围内，至少需要三个探测器，且其灵敏度需彼此接近（相差约2倍以内），并具备宽频带响应。
• 将一个LIGO探测器迁至印度，可使大量引力波信号仅通过引力波数据即被本地化至仅几平方度范围内。
• 随着基线多样性提升以及探测器间灵敏度趋于均衡，网络对源位置的本地化能力将显著增强。