A PERIODICALLY VARYING LUMINOUS QUASAR AT z = 2 FROM THE PAN-STARRS1 MEDIUM DEEP SURVEY: A CANDIDATE SUPERMASSIVE BLACK HOLE BINARY IN THE GRAVITATIONAL WAVE-DRIVEN REGIME
A PERIODICALLY VARYING LUMINOUS QUASAR AT z = 2 FROM THE PAN-STARRS1 MEDIUM DEEP SURVEY: A CANDIDATE SUPERMASSIVE BLACK HOLE BINARY IN THE GRAVITATIONAL WAVE-DRIVEN REGIME
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DOI：
10.1088/2041-8205/803/2/l16
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发表时间：
2015-03
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通讯作者：
Tingting Liu;S. Gezari;S. Heinis;E. Magnier;W. Burgett;K. Chambers;H. Flewelling;M. Huber;K. Hodapp;N. Kaiser;R. Kudritzki;J. Tonry;R. Wainscoat;C. Waters
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作者：
Tingting Liu;S. Gezari;S. Heinis;E. Magnier;W. Burgett;K. Chambers;H. Flewelling;M. Huber;K. Hodapp;N. Kaiser;R. Kudritzki;J. Tonry;R. Wainscoat;C. Waters
超大质量黑洞双星（SMBHB）应该是大质量星系通过合并和宇宙中最强的引力波（GW）警报而分层增长的必然结果。然而，由于重力束缚的 SMBHB 的轨道间隔紧凑（亚秒差距），它们的直接探测仍然难以实现。在这里，我们利用理论预测的 SMBHB 在时域中的特征：由双星轨道运动调制的质量吸积率引起的周期性变化。我们报告了 Pan-STARRS1 (PS1) 中深度巡天系统搜索中首次发现的显着周期性变化类星体。我们的 SMBHB 候选者 PSO J334.2028+01.4075 是一个 z = 2.060 的发光射电强类星体，具有来自 Catalina 实时瞬变巡天的扩展基线光度测量，以及来自 FIRST 明亮类星体巡天的档案光谱。观测周期 (542 ± 15 天) 和估计的黑洞质量 ( log ( M BH / M ⊙ ) = 9.97 ± 0.50 ?> ) 对应于 7 − 4 + 8 ?> 史瓦西半径 (∼ 0.006 − 0.003 + 0.007 ?> pc) 的轨道间隔，假设类星体变化的静止框架周期追踪双星的轨道周期。这个 SMBHB 候选者是在 SMBH 合并的红移峰值时发现的，它处于环双星吸积盘的物理稳定配置中，并且处于引力波驱动的轨道衰变范围内。我们使用 PS1 进行的搜索是 LSST 令人兴奋的功能的基准研究，它将具有更大的测量能力，并有可能在可变的夜空中精确定位数千个 SMBHB 的位置。
Supermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers and the strongest sirens of gravitational waves (GWs) in the cosmos. Yet, their direct detection has remained elusive due to the compact (sub-parsec) orbital separations of gravitationally bound SMBHBs. Here, we exploit a theoretically predicted signature of an SMBHB in the time domain: periodic variability caused by a mass accretion rate that is modulated by the binary’s orbital motion. We report our first significant periodically varying quasar detection from the systematic search in the Pan-STARRS1 (PS1) Medium Deep Survey. Our SMBHB candidate, PSO J334.2028+01.4075, is a luminous radio-loud quasar at z = 2.060, with extended baseline photometry from the Catalina Real-Time Transient Survey, as well as archival spectroscopy from the FIRST Bright Quasar Survey. The observed period (542 ± 15 days) and estimated black hole mass ( log ( M BH / M ⊙ ) = 9.97 ± 0.50 ?> ) correspond to an orbital separation of 7 − 4 + 8 ?> Schwarzschild radii ( ∼ 0.006 − 0.003 + 0.007 ?> pc), assuming the rest-frame period of the quasar variability traces the orbital period of the binary. This SMBHB candidate, discovered at the peak redshift for SMBH mergers, is in a physically stable configuration for a circumbinary accretion disk and within the regime of GW-driven orbital decay. Our search with PS1 is a benchmark study for the exciting capabilities of LSST, which will have orders of magnitude larger survey power and will potentially pinpoint the locations of thousands of SMBHBs in the variable night sky.