分类： 天文学 >> 天文学 提交时间： 2023-02-19
Weimin Yi
W. N. Brandt
Q. Ni
Luis C. Ho
Bin Luo
Wei Yan
D. P. Schneider
Jeremiah D. Paul
Richard M. Plotkin
Jinyi Yang
Feige Wang
Zhicheng He
Chen Chen
Xue-Bing Wu
Jin-Ming Bai
摘要： We present the first near-IR spectroscopy and joint analyses of multi-wavelength observations for SDSS J082747.14+425241.1, a dust-reddened, weak broad emission-line quasar (WLQ) undergoing a remarkable broad absorption line (BAL) transformation. The systemic redshift is more precisely measured to be $z=2.070\pm0.001$ using H$\beta$ compared to $z=2.040\pm0.003$ using \mgiifrom the literature, signifying an extreme \mgii\ blueshift of $2140\pm530$ \kms\ relative to H$\beta$. Using the H$\beta$-based single-epoch scaling relation with a systematic uncertainty of 0.3 dex, its black hole (BH) mass and Eddington ratio are estimated to be $M_{\rm BH}\sim6.1\times10^8M_\odot$ and $\lambda_{\rm Edd}\sim0.71$, indicative of being in a rapidly accreting phase. Our investigations confirm the WLQ nature and the LoBAL$\rightarrow$HiBAL transformation, along with a factor of 2 increase in the \mgii+\feii\ emission strength and a decrease of 0.1 in $E(B-V)$ over two decades. The kinetic power of this LoBAL wind at $R\sim$15 pc from its BH is estimated to be $\sim$43\% of the Eddington luminosity, sufficient for quasar feedback upon its host galaxy albeit with an order-of-magnitude uncertainty. This quasar provides a clear example of the long-sought scenario where LoBAL quasars are surrounded by dust cocoons, and wide-angle nuclear winds play a key role in the transition for red quasars evolving into the commonly seen blue quasars.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Q. Ni
W. N. Brandt
B. Luo
G. P. Garmire
P. B. Hall
R. M. Plotkin
O. Shemmer
J. D. Timlin
F. Vito
J. Wu
W. Yi
摘要： We present deeper Chandra observations for weak-line quasars (WLQs) in a representative sample that previously had limited X-ray constraints, and perform X-ray photometric analyses to reveal the full range of X-ray properties of WLQs. Only 5 of the 32 WLQs included in this representative sample remain X-ray undetected after these observations, and a stacking analysis shows that these 5 have an average X-ray weakness factor of > 85. One of the WLQs in the sample that was known to have extreme X-ray variability, SDSS J1539+3954, exhibited dramatic X-ray variability again: it changed from an X-ray normal state to an X-ray weak state within ~ 3 months in the rest frame. This short timescale for an X-ray flux variation by a factor of $\gtrsim$ 9 further supports the thick disk and outflow (TDO) model proposed to explain the X-ray and multiwavelength properties of WLQs. The overall distribution of the X-ray-to-optical properties of WLQs suggests that the TDO has an average covering factor of the X-ray emitting region of ~ 0.5, and the column density of the TDO can range from $N_{\rm H}$ $\sim 10^{23-24}~{\rm cm}^{-2}$ to $N_{\rm H}$ $\gtrsim 10^{24}~{\rm cm}^{-2}$, which leads to different levels of absorption and Compton reflection (and/or scattering) among WLQs.
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