The Search for Signatures of Supermassive Black Hole Binaries (and the Remnants of those Mergers) in the Time Domain

第一部分超大质量双黑洞是大质量星系合并成长的必然结果，是宇宙中最强的引力波源。然而，由于引力束缚的SMBH的轨道间隔很小，星系和黑洞变化的基本阶段的观测证据仍然很难找到。在这个程序中，提议者将利用SMBH二进制的理论预测签名：天体亮度随时间的周期性变化，由与双星轨道运动有关的质量吸积率引起。第二部分假设星系合并率、类星体寿命和亮度变化的合理值的理论估计，预测最近完成的泛星1号中深调查（PS1 MDS）的面积（80平方度），节奏（3天），基线（4.2年），和幅度的灵敏度需要检测大量的周期性类星体的阶段期间，他们的二进制SMBH的轨道衰变造成的重力波。在这个项目中，PI将分析所有10个PS1 MDS场，包括7,000多个光度选择的类星体。此外，他们将利用即将到来的Zwicky Transient Facility（ZTF）的广阔区域和出色的节奏，使用差分成像来搜索在空间上偏离其宿主星系中心的活动星系核，这可能表明存在反冲的SMBH合并残留物。这两项研究将为大型综合巡天望远镜（LSST）的令人兴奋的能力提供基准研究，LSST将具有更大的巡天能力。

Part 1Binary supermassive black holes (SMBHs) should be an inevitable consequence of the growth of massive galaxies through mergers, and the strongest source of gravitational waves in the universe. However, observational evidence for this fundamental phase of changes in galaxy and black hole has remained hard to find due to the small orbital separations of gravitationally bound SMBHs. In this program, the proposers will exploit a theoretically predicted signature of a SMBH binary: periodic changes of the object's brightness over time, caused by a mass accretion rate that is linked to the binary's orbital motion.Part 2Theoretical estimates assuming reasonable values for the galaxy merger rates, quasar lifetime, and brightness variations, predict that the recently completed Pan-STARRS1 Medium Deep Survey (PS1 MDS) has the area (80 square degrees), cadence (3 days), baseline (4.2 years), and magnitude sensitivity required to detect a significant number of periodic quasars during the phase of their binary SMBHs's orbital decay cause by gravity waves. In this project the PIs will analyze all 10 PS1 MDS fields, including over 7,000 photometrically-selected quasars. Furthermore, they will exploit the wide area and excellent cadence of the upcoming Zwicky Transient Facility (ZTF) to use difference imaging to search for active galactic nuclei spatially offset from their host galaxy center, potentially indicative of a recoiling SMBH merger remnant. Both searches will provide benchmark studies for the exciting capabilities of Large Synoptic Survey Telescope (LSST), which will have orders of magnitude larger survey power.