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 the discovery of a new $z \sim 6.8$ quasar discovered with the
near-IR VISTA Hemisphere Survey (VHS) which has been spectroscopically
confirmed by the ESO New Technology Telescope (NTT) and the Magellan telescope.
This quasar has been selected by spectral energy distribution (SED)
classification using near infrared data from VISTA, optical data from
Pan-STARRS, and mid-IR data from WISE. The SED classification algorithm is used
to statistically rank two classes; foreground Galactic low-mass stars and high
redshift quasars, prior to spectroscopic observation. Forced photometry on
Pan-STARRS pixels for VHS J0411-0907 allows to improve the SED classification
reduced-$\chi^2$ and photometric redshift. VHS J0411-0907 ($z=6.82$, $y_{AB} =
20.1$ mag, $J_{AB} = 20.0$ mag) has the brightest J-band continuum magnitude of
the nine known quasars at $z > 6.7$ and is currently the highest redshift
quasar detected in the Pan-STARRS survey. This quasar has one of the lowest
black hole mass ($M_{\rm{BH}}= (6.13 \pm 0.51)\times 10^8\:\mathrm{M_{\odot}}$)
and the highest Eddington ratio ($2.37\pm0.22$) of the known quasars at
$z>6.5$. The high Eddington ratio indicates that some very high-$z$ quasars are
undergoing super Eddington accretion. We also present coefficients of the best
polynomials fits for colours vs spectral type on the Pan-STARRS, VISTA and WISE
system for MLT dwarfs and present a forecast for the expected numbers of
quasars at $z>6.5$.

利用光谱能量分布分类算法在 Pan-STARRS、VISTA、WISE 数据上统计排名高红移类星体和前景银河低质量恒星，选取并通过对 VHS J0411-0907 的强迫光度测量得到光谱和光度法红移，并确定该天体为目前红移最高的夸克星，它具有已知红移大于 6.5 的夸克星中最低的黑洞质量和最高的爱丁顿比，表明一些非常高红移的夸克星正在经历超爱丁顿吸积。同时，我们还提出了多项式拟合系数和 $z>6.5$ 量子的预期数。