Statistics of Galactic-scale Quasar Pairs at Cosmic Noon
Statistics of Galactic-scale Quasar Pairs at Cosmic Noon
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DOI：
10.3847/1538-4357/aca662
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Yue Shen;H. Hwang;M. Oguri;Nianyi Chen;T. Matteo;Y. Ni;Simeon Bird;N. Zakamska;Xin Liu;Yu-Ching Chen;K. Kratter
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作者：
Yue Shen;H. Hwang;M. Oguri;Nianyi Chen;T. Matteo;Y. Ni;Simeon Bird;N. Zakamska;Xin Liu;Yu-Ching Chen;K. Kratter
星系尺度类星体对的统计数据可以阐明我们对超大质量黑洞(SMBH)对的动力学演化、合并中类星体活动的占空比，甚至暗物质的性质的理解，但在宇宙正午，也就是大质量星系和SMBH形成的黄金时代，测量它们一直是具有挑战性的。在这里，我们测量了∼6.2±0.5×10−4在∼0上积分的一个双类星体分数。用Gaia EDR3分辨对对SDSS DR16类星体进行了“3-3”分离(∼3-30kpc在z∼2处的投影物理分离)在1.5<；z<；3.5处未遮挡的类星体中(L和S−1)。这项测量是基于60颗Gaia分辨的双类星体的样本(由类星体+恒星叠加主导的487对Gaia对中的)，修正了Gaia中的对完整性，我们将其量化为对分离、主星等和星等对比度的函数。在这些尺度上，双类星体的比例朝着更小的分离方向增加了∼5倍。在我们的样本中，物理类星体对和透镜类星体之间的划分目前尚不清楚，需要专门的后续观测(特别是对最接近的类星体对进行深亚弧秒分辨率的红外成像)。有趣的是，在这一点上，观测到的对统计数据与理论预测大致一致，无论是对于模拟星表中的透镜类星体群体，还是对于宇宙流体动力学模拟中的双类星体。即将到来的广视场成像/光谱太空任务，如欧几里得、CSST和ROMAN，结合有针对性的后续观测，将最终测量跨宇宙时间的星系尺度类星体对、偏置活动星系核和亚弧秒透镜类星体的丰度和所在星系的性质。
The statistics of galactic-scale quasar pairs can elucidate our understanding of the dynamical evolution of supermassive black hole (SMBH) pairs, the duty cycles of quasar activity in mergers, or even the nature of dark matter, but they have been challenging to measure at cosmic noon, the prime epoch of massive galaxy and SMBH formation. Here we measure a double quasar fraction of ∼6.2 ± 0.5 × 10−4 integrated over ∼0.″3–3″ separations (projected physical separations of ∼3–30 kpc at z ∼ 2) in luminous (L bol > 1045.8 erg s−1) unobscured quasars at 1.5 < z < 3.5 using Gaia EDR3-resolved pairs around SDSS DR16 quasars. The measurement was based on a sample of 60 Gaia-resolved double quasars (out of 487 Gaia pairs dominated by quasar+star superpositions) at these separations, corrected for pair completeness in Gaia, which we quantify as functions of pair separation, magnitude of the primary, and magnitude contrast. The double quasar fraction increases toward smaller separations by a factor of ∼5 over these scales. The division between physical quasar pairs and lensed quasars in our sample is currently unknown, requiring dedicated follow-up observations (in particular, deep, subarcsecond-resolution IR imaging for the closest pairs). Intriguingly, at this point, the observed pair statistics are in rough agreement with theoretical predictions both for the lensed quasar population in mock catalogs and for dual quasars in cosmological hydrodynamic simulations. Upcoming wide-field imaging/spectroscopic space missions such as Euclid, CSST, and Roman, combined with targeted follow-up observations, will conclusively measure the abundances and host galaxy properties of galactic-scale quasar pairs, offset AGNs, and subarcsecond lensed quasars across cosmic time.