本文利用近红外光谱研究十个 z~2 弱发射线类星体，通过 Hβ 测量黑洞质量与爱丁顿比率，发现其 [O III] 普遍微弱、Fe II 较强，支持超爱丁顿吸积导致弱线的解释。
摘要：
我们利用帕洛马200英寸海尔望远镜获得了十个红移 z~2 的弱发射线类星体（WLQs）的近红外光谱。WLQs 是一类特殊的 1 型类星体，它们在紫外波段表现出微弱或没有宽发射线（例如 C IV λ1549 线），并显示出显著的 X 射线性质。我们为这些源推导了基于 Hβ 的单历元维里黑洞质量（中值 1.7 × 10^9 M⊙）和爱丁顿比率（中值 0.5）。我们证实了此前的发现，即 WLQ 的 Hβ 线作为一种主要的低电离线，与典型类星体相比并没有显著变弱。WLQ 光学光谱最突出的特征是普遍微弱或缺失的 [O III] λ5007 发射。它们还表现出比典型类星体更强的光学 Fe II 发射。我们的结果支持 WLQs 的超爱丁顿吸积图像，在该图像中，弱线是软电离连续谱的结果；几何上厚的内部吸积盘和/或其相关的外流负责遮蔽核区高能辐射并产生软电离连续谱。我们还在一个天体中报告了候选的极端 [O III] 外流（蓝移约为 500 和 4900 km s^-1）。
英文摘要：
We present near-infrared spectroscopy of ten weak emission-line quasars (WLQs) at redshifts of $z\sim2$, obtained with the Palomar 200-inch Hale Telescope. WLQs are an exceptional population of type 1 quasars that exhibit weak or no broad emission lines in the ultraviolet (e.g., the C IV $λ1549$ line), and they display remarkable X-ray properties. We derive H$β$-based single-epoch virial black-hole masses (median value $\rm 1.7 \times 10^{9} M_{\odot}$) and Eddington ratios (median value $0.5)$ for our sources. We confirm the previous finding that WLQ H$β$ lines, as a major low-ionization line, are not significantly weak compared to typical quasars. The most prominent feature of the WLQ optical spectra is the universally weak/absent [O III] $λ5007$ emission. They also display stronger optical Fe II emission than typical quasars. Our results favor the super-Eddington accretion scenario for WLQs, where the weak lines are a result of a soft ionizing continuum; the geometrically thick inner accretion disk and/or its associated outflow is responsible for obscuring the nuclear high-energy radiation and producing the soft ionizing continuum. We also report candidate extreme [O III] outflows (blueshifts of $\approx 500$ and $\rm 4900 km s^{-1}$) in one object.
We report the results of analysis of the Hbeta emission-line region of a sample of thirty low-redshift (z<1) iron low-ionization broad absorption line quasars (FeLoBALQs). Eleven of these objects are newly classified as FeLoBALQs. A matched sample of 132 unabsorbed quasars was analyzed in parallel. The emission lines showed the well known anticorrelation between the [OIII] and FeII emission (Boroson & Green 1992). Using a summary statistic called E1 to quantify this anticorrelation, we found that while the distribution of E1 for the unabsorbed quasars has a single peak, the FeLoBALQs have a bi…
From Hubble Space Telescope/Cosmic Origins Spectrograph spectra of five quasars, 16 outflows are detected. For 11 outflows, we are able to constrain their distances to the central source (R) and their energetics. In instances of multiple electron number density determinations (used in the calculation of R) for the same outflow, the values are consistent within errors. For the 11 outflows, eight have measurements for R (between 10 and 1000 pc), one has a lower limit, another has an upper limit, and the last has a range in R. There are two outflows that have enough kinetic luminosity to be major…
We report on a Hubble Space Telescope search for rest-frame ultraviolet emission from the host galaxies of five far-infrared-luminous $z\simeq{}6$ quasars and the $z=5.85$ hot-dust free quasar SDSS J0005-0006. We perform 2D surface brightness modeling for each quasar using a Markov-Chain Monte-Carlo estimator, to simultaneously fit and subtract the quasar point source in order to constrain the underlying host galaxy emission. We measure upper limits for the quasar host galaxies of $m_J>22.7$ mag and $m_H>22.4$ mag, corresponding to stellar masses of $M_\ast<2\times10^{11}M_\odot$. These stella…
HST/COS Observations of Quasar Outflows in the 500 -- 1050 Å Rest Frame: IV. The Largest Broad Absorption Line Acceleration
本文分析了类星体SDSS J1042+1646的一个外流系统中出现的宽吸收线（BAL）速度漂移。哈勃太空望远镜/宇宙起源光谱仪在2011年和2017年在500 - 1050 $Å$静止框架中进行了观测。在3.2年的静止帧时间内，外流的速度中心移动了1550 km s $\sim$，从19，500 km s $^{-1}$移动到21，050 km s $^{-1}$。速度漂移特征在来自Ne VIII $λλ$ 770.41、780.32双重峰的吸收特征中最为明显，并且得到来自OV $λ$ 629.73和Mg X $λλ$ 609.79、624.94双重峰的吸收槽的支持。这是第一次观察到类星体流出速度的变化，在槽从一个以上的离子，并在不同的槽从一个双重跃迁（Ne VIII）。我们将速度变化归因于现有外流的加速，因为我们能够排除光电离变化和物质进出视线的运动作为替代解释。这导致在类星体静止框架中的平均加速度为480 km s $^{-1}$ yr $^{-1}$（1.52 cm s $^{-2}$）。加速度和绝对速度变化都是迄今为止报道的类星体外流中最大的。根据O V* 多重峰的吸收谷，我们推导出流出（$R$）到中心源的距离范围，为0.05 pc $<$ $R$ $<$ 54.3 pc.这种外流与类星体PG 1211+143中检测到的快速X射线外流有相似之处。我们使用加速度和速度变化来约…
Direct measurements of the masses of supermassive black holes (SMBHs) are key to understanding their growth and constrain their symbiotic relationship to their host galaxies. However, current methods used to directly measure black hole masses in active quasars become challenging or impossible beyond $z\gtrsim0.2$. Spectroastrometry (SA) measures the spatial centroid of an object's spectrum as a function of wavelength, delivering angular resolution far better than the point-spread function (PSF) for high signal-to-noise ratio observations. We observed the luminous quasar SDSS J212329.47--005052…
Extremely red quasars (ERQs) are an interesting sample of quasars in the Baryon Oscillation Spectroscopic Sample (BOSS) in the redshift range of $2.0 - 3.4$ and have extreme red colours of $i-W3\ge4.6$. Core ERQs have strong CIV emission lines with rest equivalent width of $\ge100$Å. Many core ERQs also have CIV line profiles with peculiar boxy shapes which distinguish them from normal blue quasars. We show, using a combination of kernel density estimation and local outlier factor analyses on a space of the $i-W3$ colour, CIV rest equivalent width and line kurtosis, that core ERQs likely repre…
The rest ultraviolet to infrared spectral energy distributions of heavily reddened quasars are "V-shaped" and hot-dust poor
School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学学院）；Centre for Extragalactic Astronomy, Department of Physics, Durham University（杜伦大学物理系河外天文中心）；Institute of Astronomy, University of Cambridge（剑桥大学天文学研究所）
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame: III. Four Similar Outflows in 2MASS J1051+1247 with Enough Energy to be Major Contributors to AGN Feedback
我们在哈勃空间望远镜/宇宙起源摄谱仪的类星体2 MASS J1051+1247的光谱中探测到四个非常有活力的外流，其组合动力学光度（$\dot{E_k}$）为10 $^{46}$ erg s $^{-1}$。显着的相似之处被认为是在这些流出：4900和5700公里秒$^{-1}$之间的速度质心，距离中央源（$R$）的几百秒差距内的错误都是一致的，和一个$\dot{E_k}$内的一个因素为2的所有流出。因此，外流的共同来源是可能的。大部分流出的物质存在于一个非常高的电离阶段，明显的是来自Ne VIII，Na IX，Mg X和Si XII的波谷，这将这些紫外线流出的物理条件与附近塞弗特星系中看到的X射线暖吸收体流出相连接。三个流出具有两个或三个独立的诊断的电子数密度，产生一致的值为每个流出，这增加了稳健性的$R$测定。槽从未见过的Ar VI，O IV*，Ne VI*，和Ne V* 的离子跃迁被确定。结合$\dot{E_k}$是类星体的爱丁顿光度的$7.0^{+6.5}_{-2.3}$ %，这些外流是主要的候选人是各种活动星系核反馈效应的主要代理人。
We present deep Keck/MOSFIRE near-infrared spectroscopy of a strong Lyman alpha emitting source at z=6.1292, HSC J142331.71-001809.1, which was discovered by the SHELLQS program from imaging data of the Subaru Hyper Suprime-Cam (HSC) survey. This source is one of five objects that show unresolved (<230 km s-1) and prominent (>10^44 erg s-1) Lyman alpha emission lines at absolute 1450 angstrom continuum magnitudes of M1450~-22 mag. Its rest-frame Lyman alpha equivalent width (EW) is 370+/-30 angstrom. In the 2 hour Keck/MOSFIRE spectrum in Y band, the high-ionization CIV 1548,1550 doublet emiss…
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame: V. Richness of Physical Diagnostics and Ionization Potential-dependent Velocity Shift in PKS J0352-0711
我们分析吸收槽从两个流出PKS J 0352 -0711（S1在$-$ 1950 km s $^{-1}$和S2在$-$ 3150 km s $^{-1}$）从哈勃太空望远镜/宇宙起源摄谱仪，其中包括诊断丰富的585-900埃静止帧波长范围内的光谱。在S2中，我们首次清楚地检测到Ca IV、Ca V、Ca V*、Ca VII* 和Ca VIII* 的吸收谷。Ca V柱密度测量表明S2具有超太阳的金属丰度。两种流出都需要至少两个电离阶段，其中非常高电离阶段的柱密度大约是对应的高电离阶段的15倍。这些高柱密度和非常高的电离势离子类似于X射线暖吸收体。S2的两个相位显示了相关波谷之间的独特速度质心偏移。通过Monte Carlo测量的O V* 吸收槽，我们确定的电子数密度S2（完全证实了独立的测量从钙V* 和钙VIII* 槽），产生的距离为9 pc和动力学光度为2 $\times$ 10 $^{43}$尔格s $^{-1}$。S1位于距离中心源500秒差距处，动力学光度为10 $^{43}$ erg s $^{-1}$。
A key assumption in quasar absorption line studies of the circumgalactic medium (CGM) is that each absorption component maps to a spatially isolated "cloud" structure that has single valued properties (e.g. density, temperature, metallicity). We aim to assess and quantify the degree of accuracy underlying this assumption. We used adaptive mesh refinement hydrodynamic cosmological simulations of two $z=1$ dwarf galaxies and generated synthetic quasar absorption-line spectra of their CGM. For the SiII $λ1260$ transition, and the CIV $λ\lambda1548, 1550$ and OVI $λ\lambda1031, 1037$ fine-structur…
A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of $z > 6.5$ Quasars Using JWST
We investigated the rest-frame $\approx$0.1-5 year X-ray variability properties of an unbiased and uniformly selected sample of 24 BAL and 35 mini-BAL quasars, making it the largest representative sample used to investigate such variability. We find that the distributions of X-ray variability amplitudes of these quasar populations are statistically similar to that of non-BAL, radio-quiet (typical) quasars.
The rest-frame UV/optical variability of the quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 is used to test the Corona-Heated Accretion-disk Reprocessing (CHAR) model of Sun et al. 2020. We adopt our CHAR model and the observed black-hole masses ($M_{\mathrm{BH}}$) and luminosities ($L$) to generate mock light curves that share the same measurement noise and sampling as the real observations. Without any fine-tuning, our CHAR model can satisfactorily reproduce the observed ensemble structure functions for different $M_{\mathrm{BH}}$, $L$, and rest-frame wavelengths. Our analyses reve…
Rest-frame Optical Spectroscopy of $z \sim 2$ Quasars with Steep Hard X-ray Spectral Shapes: X-ray Selection of Super-Eddington Accretion and Verification
Prescriptions for Correcting Ultraviolet-Based Redshifts for Luminous Quasars at High Redshift
高红移类星体的红移通常是由静止坐标系的紫外线（UV）发射线决定的。然而，这些线，更具体地说，突出的C IV $λ1549$发射线，通常是蓝移产生高度不确定的红移估计相比，从静止帧光发射线确定的红移。我们目前的近红外光谱的18个发光类星体在$2.15 < z < 3.70$，使我们能够获得可靠的系统红移这些来源。再加上近红外光谱的44个类星体具有可比的光度和红移的档案样本，我们提供了纠正紫外红移的处方。我们的处方减少速度偏移相对于系统的红移由$\sim140$公里的$^{-1}$和减少的不确定性的紫外线为基础的红移由$\sim25\%$相对于目前用于确定这些值的最佳方法。我们还发现，从斯隆数字巡天管道为我们的来源确定的红移遭受显着的不确定性，这是不容易减轻。我们讨论了我们的处方，以提高基于紫外线的红移校正的潜在的一个更大的样本的高红移类星体与近红外光谱。
