Supermassive black hole binaries (SMBHBs) are thought to form in galaxy mergers, possessing the potential to produce electromagnetic (EM) radiation as well as gravitational waves (GWs) detectable with pulsar timing arrays (PTAs). Once GWs from individually resolved SMBHBs are detected, the identification of the host galaxy will be a major challenge due to the ambiguity in possible EM signatures and the poor localization capability of PTAs. To aid EM observations in choosing follow-up sources, we use NANOGrav’s galaxy catalog to quantify the number of plausible hosts in both realistic and idealistic scenarios. We outline a host identification pipeline that injects a single-source GW signal into a simulated PTA data set, recovers the signal using production-level techniques, quantifies the localization region and number of galaxies contained therein, and finally imposes cuts on the galaxies using parameter estimates from the GW search. In an ideal case, the 90% credible areas span 29–241 deg2, containing about 14–341 galaxies. After cuts, the number of galaxies remaining ranges from 22 at worst to one true host at best. In a realistic case, these areas range from 287 to 530 deg2 and enclose about 285–1238 galaxies. After cuts, the number of galaxies is 397 at worst and 27 at best. While the signal-to-noise ratio is the primary determinant of the localization area of a given source, we find that the area is also influenced by the proximity to nearby pulsars on the sky and the binary chirp mass.

中文翻译：

---

识别 Pulsar 计时阵列发现的超大质量黑洞双星的宿主星系


超大质量黑洞双星 （SMBHB） 被认为是在星系合并中形成的，具有产生电磁 （EM） 辐射的潜力以及脉冲星计时阵列 （PTA） 可探测到的引力波 （GW）。一旦检测到来自单独解析的 SMBHB 的 GWs，由于可能的 EM 特征的歧义和 PTA 的定位能力差，宿主星系的识别将是一个重大挑战。为了帮助 EM 观测选择后续来源，我们使用 NANOGrav 的星系目录来量化现实和理想情况下可能的宿主数量。我们概述了一个主机识别管道，该管道将单源 GW 信号注入模拟的 PTA 数据集中，使用生产级技术恢复信号，量化其中包含的定位区域和星系数量，最后使用 GW 搜索的参数估计对星系进行切割。在理想情况下，90% 可信区域跨越 29-241 度2，包含大约 14-341 个星系。切割后，剩余的星系数量从最坏的 22 个到最好的一个真正的宿主不等。在现实情况下，这些区域的范围从 287 到 530 度2 不等，并包围了大约 285-1238 个星系。切割后，星系的数量最差是 397 个，最好的是 27 个。虽然信噪比是给定源定位区域的主要决定因素，但我们发现该区域还受到与天空中附近脉冲星的接近程度和二进制啁啾质量的影响。