科研之友
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摘要
Quasars (QSOs) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. However, many observations revealed average or low galaxy densities around z greater than or similar to 6 QSOs. This could be partly because they measured galaxy densities in only tens of arcmin(2) around QSOs and might have overlooked potential larger-scale galaxy overdensities. Some previous studies also observed only Lyman break galaxies (LBGs; massive older galaxies) and missed low-mass young galaxies, like Lya emitters (LAEs), around QSOs. Here we present observations of LAE and LBG candidates in similar to 700 arcmin(2) around a z = 6.61 luminous QSO using the Subaru Telescope Suprime-Cam with narrowband/broadband. We compare their sky distributions, number densities, and angular correlation functions with those of LAEs/LBGs detected in the same manner and comparable data quality in our control blank field. In the QSO field, LAEs and LBGs are clustering in 4-20 comoving Mpc angular scales, but LAEs show mostly underdensity over the field while LBGs are forming 30 x 60 comoving Mpc(2) large-scale structure containing 3 sigma-7 sigma high-density clumps. The highest-density clump includes a bright (23.78 mag in the narrowband) extended (greater than or similar to 16 kpc) Lya blob candidate, indicative of a dense environment. The QSO could be part of the structure but is not located exactly at any of the high-density peaks. Near the QSO, LAEs show underdensity while LBGs average to 4 sigma excess densities compared to the control field. If these environments reflect halo mass, the QSO may not be in the most massive halo but still in a moderately massive one.
- 出版日期2018-4-1
- 单位北京大学; 中国科学院国家天文台
