Binaries of relatively massive black holes like GW190521 have been proposed to form in dense gas environments, such as the disks of active galactic nuclei (AGNs), and they might be associated with transient electromagnetic counterparts. The interactions of this putative environment with the binary could leave a significant imprint at the low gravitational wave frequencies observable with the Laser Interferometer Space Antenna (LISA). We show that LISA will be able to detect up to ten GW190521-like black hole binaries, with sky position errors $\lesssim 1{\mathrm{deg}}^2$. Moreover, it will measure directly various effects due to the orbital motion around the supermassive black hole at the center of the AGN, especially the Doppler modulation and the Shapiro time delay. Thanks to a careful treatment of their frequency domain signal, we were able to perform the full parameter estimation of Doppler and Shapiro-modulated binaries as seen by LISA. We find that the Doppler and Shapiro effects will allow for measuring the AGN parameters (radius and inclination of the orbit around the AGN, central black hole mass) with up to percent-level precision. Properly modeling these low-frequency environmental effects is crucial to determine the binary formation history, as well as to avoid biases in the reconstruction of the source parameters and in tests of general relativity with gravitational waves.

中文翻译：

---

用 LISA 观测类似 GW190521 的双星黑洞及其环境

已经提出像 GW190521 这样的相对大质量黑洞的双星在稠密的气体环境中形成，例如活动星系核 (AGN) 的圆盘，它们可能与瞬态电磁对应物有关。这种假定环境与双星的相互作用可能会在激光干涉仪空间天线 (LISA) 可观测到的低引力波频率上留下明显的印记。我们证明 LISA 将能够检测到多达 10 个类似 GW190521 的黑洞双星，但存在天空位置错误$\lesssim 1{度}^2$. 此外，它将直接测量由于活动星系核中心超大质量黑洞周围的轨道运动产生的各种影响，特别是多普勒调制和夏皮罗时间延迟。由于对其频域信号的仔细处理，我们能够执行 LISA 所见的多普勒和夏皮罗调制二进制文件的完整参数估计。我们发现多普勒和夏皮罗效应将允许测量活动星系核参数（活动星系核周围轨道的半径和倾角，中心黑洞质量），精度高达百分比。正确模拟这些低频环境效应对于确定二元形成历史以及避免在重建源参数和使用引力波进行广义相对论测试中出现偏差至关重要。