We present the discovery of PSO J083.8371+11.8482, a weak emission line
quasar with extreme star formation rate at $z=6.3401$. This quasar was selected
from Pan-STARRS1, UHS, and unWISE photometric data. Gemini/GNIRS spectroscopy
follow-up indicates a MgII-based black hole mass of
$M_\mathrm{BH}=\left(2.0^{+0.7}_{-0.4}\right)\times10^9~M_\odot$ and an
Eddington ratio of $L_\mathrm{bol}/L_\mathrm{Edd}=0.5^{+0.1}_{-0.2}$, in line
with actively accreting supermassive black hole (SMBH) at $z\gtrsim6$. HST
imaging sets strong constraint on lens-boosting, showing no relevant effect on
the apparent emission. The quasar is also observed as a pure point-source with
no additional emission component. The broad line region (BLR) emission is
intrinsically weak and not likely caused by an intervening absorber. We found
rest-frame equivalent widths of EW(Ly$\alpha$+NV) $=5.7\pm0.7$ Angstrom,
EW(CIV) $\leq5.8$ Angstrom (3-sigma upper limit), and EW(MgII) $=8.7\pm0.7$
Angstrom. A small proximity zone size ($R_\mathrm{p}=1.2\pm0.4$ pMpc) indicates
a lifetime of only $t_\mathrm{Q}=10^{3.4\pm0.7}$ years from the last quasar
phase ignition. ALMA shows extended [CII] emission with a mild velocity
gradient. The inferred far-infrared luminosity
($L_\mathrm{FIR}=(1.2\pm0.1)\times10^{13}\,L_\odot$) is one of the highest
among all known quasar hosts at $z\gtrsim6$. Dust and [CII] emissions put a
constraint on the star formation rate of SFR
$=900-4900~M_\odot\,\mathrm{yr^{-1}}$, similar to that of hyper-luminous
infrared galaxy. Considering the observed quasar lifetime and BLR formation
timescale, the weak-line profile in the quasar spectrum is most likely caused
by a BLR which is not yet fully formed rather than continuum boosting by
gravitational lensing or a soft continuum due to super-Eddington accretion.

发现了一个处于高红移的暗星系团，该星系团伴随着一个活跃的超大质量黑洞，其引力逐渐收缩并吸收周围的气体从而释放出大量的辐射，同时该星系团的性质也提示了这个宇宙时期中宇宙形成和演化的一些有趣特性。

高红移弱发射线类星体的本质探究：一个带有星暴宿主星系的年轻类星体

Probing the Nature of High Redshift Weak Emission Line Quasars: A Young  Quasar with a Starburst Host Galaxy

We present deep near-infrared spectroscopy of six quasars at 6.1<z<6.7 with
VLT/X-Shooter and Gemini-N/GNIRS. Our objects, originally discovered through a
wide-field optical survey with the Hyper Suprime-Cam (HSC) Subaru Strategic
Program (HSC-SSP), have the lowest luminosities (-25.5< M1450<-23.1 mag) of the
z>5.8 quasars with measured black hole masses. From single-epoch mass
measurements based on MgII2798, we find a wide range in black hole masses, from
M_BH=10^7.6 to 10^9.3 Msun. The Eddington ratios L_bol/L_Edd range from 0.16 to
1.1, but the majority of the HSC quasars are powered by M_BH=10^9 Msun
supermassive black holes (SMBHs) accreting at sub-Eddington rates. The
Eddington ratio distribution of the HSC quasars is inclined to lower accretion
rates than those of Willott et al. (2010a), who measured the black hole masses
for similarly faint z=6 quasars. This suggests that the global Eddington ratio
distribution is wider than has previously been thought. The presence of
M_BH=10^9 Msun SMBHs at z=6 cannot be explained with constant sub-Eddington
accretion from stellar remnant seed black holes. Therefore, we may be
witnessing the first buildup of the most massive black holes in the first
billion years of the universe, the accretion activity of which is transforming
from active growth to a quiescent phase. Measurements of a larger complete
sample of z>6 low-luminosity quasars, as well as deeper observations with
future facilities will enable us to better understand the early SMBH growth in
the reionization epoch.

使用 VLT / X-Shooter 和 Gemini-N / GNIRS 等天文观测设备对 6.1 <z <6.7 范围内的六个类星体进行了深入的近红外光谱研究，发现其中的 10⁹个太阳质量超大质量黑洞（SMBHs）正在以亚 Eddington 速率凝聚，这表明我们可能目睹了宇宙的第一个十亿年中最巨大的黑洞的形成和生长过程。

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VI. 6.1<z<6.7 的六个类星体的黑洞质量测量

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VI. Black  Hole Mass Measurements of Six Quasars at 6.1<z<6.7

We have newly identified a substantial number of type 1 active galactic
nuclei (AGN) featuring weak broad-line regions (BLRs) at z < 0.2 from detailed
analysis of galaxy spectra in the Sloan Digital Sky Survey Data Release 7.
These objects predominantly show a stellar continuum but also a broad H-alpha
emission line, indicating the presence of a low-luminosity AGN oriented so that
we are viewing the central engine directly without significant obscuration.
These accreting black holes have previously eluded detection due to their weak
nature. The new BLR AGNs we found increased the number of known type 1 AGNs by
49%. Some of these new BLR AGNs were detected at the Chandra X-ray Observatory,
and their X-ray properties confirm that they are indeed type 1 AGN. Based on
our new and more complete catalogue of type 1 AGNs, we derived the type 1
fraction of AGNs as a function of [OIII] 5007 emission luminosity and explored
the possible dilution effect on the obscured AGN due to star-formation. The new
type 1 AGN fraction shows much more complex behavior with respect to black hole
mass and bolometric luminosity than suggested by the existing receding torus
model. The type 1 AGN fraction is sensitive to both of these factors, and there
seems to be a sweet spot (ridge) in the diagram of black hole mass and
bolometric luminosity. Furthermore, we present a hint that the Eddington ratio
plays a role in determining the opening angles.

在斯隆数字天文巡天数据发布 7 中，我们新鉴定了大量 z < 0.2 的特 1 活动星系核（AGN），它们有弱的宽带线区域（BLRs），主要表现出恒星连续体和宽 H-alpha 发射线并由其低辐射力 AGN 控制；通过对这些 AGN 进行更全面的分类，研究发现黑洞质量和辐射通量对特 1 AGN 的作用，Eddington 比例在决定开口角度时也十分重要。