分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Traditional classification for subclass of the Seyfert galaxies is visual inspection or using a quantity defined as a flux ratio between the Balmer line and forbidden line. One algorithm of deep learning is Convolution Neural Network (CNN) and has shown successful classification results. We building a 1-dimension CNN model to distinguish Seyfert 1.9 spectra from Seyfert 2 galaxies. We find our model can recognize Seyfert 1.9 and Seyfert 2 spectra with an accuracy over 80% and pick out an additional Seyfert 1.9 sample which was missed by visual inspection. We use the new Seyfert 1.9 sample to improve performance of our model and obtain a 91% precision of Seyfert 1.9. These results indicate our model can pick out Seyfert 1.9 spectra among Seyfert 2 spectra. We decompose H{\alpha} emission line of our Seyfert 1.9 galaxies by fitting 2 Gaussian components and derive line width and flux. We find velocity distribution of broad H{\alpha} component of the new Seyfert 1.9 sample has an extending tail toward the higher end and luminosity of the new Seyfert 1.9 sample is slightly weaker than the original Seyfert 1.9 sample. This result indicates that our model can pick out the sources that have relatively weak broad H{\alpha} component. Besides, we check distributions of the host galaxy morphology of our Seyfert 1.9 samples and find the distribution of the host galaxy morphology is dominant by large bulge galaxy. In the end, we present an online catalog of 1297 Seyfert 1.9 galaxies with measurement of H{\alpha} emission line.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Systems with ultra-short-period planets (USPs) tend to possess larger mutual inclinations compared to those with planets located farther from their host stars. This could be explained due to precession caused by stellar oblateness at early times when the host star was rapidly spinning. However, stellar oblateness reduces over time due to the decrease in the stellar rotation rate, and this may further shape the planetary mutual inclinations. In this work, we investigate in detail how the final mutual inclination varies under the effect of a decreasing $J_2$. We find that different initial parameters (e.g., the magnitude of $J_2$ and planetary inclinations) will contribute to different final mutual inclinations, providing a constraint on the formation mechanisms of USPs. In general, if the inner planets start in the same plane as the stellar equator (or co-planar while misaligned with the stellar spin-axis), the mutual inclination decreases (or increases then decreases) over time due to the decay of the $J_2$ moment. This is because the inner orbit typically possesses less orbital angular momentum than the outer ones. However, if the outer planet is initially aligned with the stellar spin while the inner one is misaligned, the mutual inclination nearly stays the same. Overall, our results suggest that either the USP planets formed early and acquired significant inclinations (e.g., $\gtrsim30^\circ$ with its companion or $\gtrsim10^\circ$ with its host star spin-axis for Kepler-653c) or they formed late ($\gtrsim$Gyr) when their host stars rotate slower.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： It is common to assume that all narrow absorption lines (NALs) at extreme high-velocity shifts form in cosmologically intervening gas or galaxies unrelated to quasars. However, previous detailed studies of individual quasars have shown that some NALs at these large velocity shifts do form in high-speed quasar ejecta. We search for extreme high-velocity NAL outflows (with speeds $\sim$0.1-0.2c) based on relationships with associated absorption lines (AALs) and broad absorption-line (BAL) outflows. We find that high-velocity NALs are strongly correlated with AALs, BALs, and radio loudness, indicating that a significant fraction of high-velocity systems are either ejected from the quasars or form in material swept up by the radio jets (and are not unrelated intervening gas). We also consider line-locked C IV doublets as another indicator of high-velocity NALs formed in outflows. The fact that line-locked NALs are highly ionized and correlated with BAL outflows and radio-loud quasars implies that physical line locking due to radiative forces is both common and real, which provides indirect evidence that a significant fraction of high-velocity NALs are intrinsic to quasars.
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2023-10-17 合作期刊: 《干旱区科学》
摘要： Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas. In this study, we selected 244 sampling sites around a typical lead (Pb) and zinc (Zn) mining area in eastern Inner Mongolia Autonomous Region of China and measured the content of six heavy metals, including cuprum (Cu), Zn, Pb, arsenic (As), cadmium (Cd), and chromium (Cr). The ecological risk of heavy metals was comprehensively evaluated using the Geo-accumulation index, Nemerow general pollution index, and potential ecological risk index. The heavy metals were traced using correlation analysis and principal component analysis. The results showed that the highest content of heavy metals was found in 05 cm soil layer in the study area. The average content of Zn, As, Pb, Cu, Cr, and Cd was 670, 424, 235, 162, 94, and 4 mg/kg, respectively, all exceeding the risk screening value of agricultural soil in China. The areas with high content of soil heavy metals were mainly distributed near the tailings pond. The study area was affected by a combination of multiple heavy metals, with Cd and As reaching severe pollution levels. The three pathways of exposure for carcinogenic and noncarcinogenic risks were ranked as inhalation>oral ingestion>dermal absorption. The heavy metals in the study area posed certain hazards to human health. Specifically, oral ingestion of these heavy metals carried carcinogenic risks for both children and adults, as well as noncarcinogenic risks for children. There were differences in the sources of different heavy metals. The tailings pond had a large impact on the accumulation of Cd, Zn, and Pb. The source of Cr was the soil parent material, the source of As was mainly the soil matrix, and the source of Cu was mainly the nearby Cu ore. The purpose of this study is to more accurately understand the extent, scope, and source of heavy metals pollution near a typical mining area, providing effective help to solve the problem of heavy metals pollution.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Zhicheng He
Guilin Liu
Tinggui Wang
Guobin Mou
Richard Green
Weihao Bian
Huiyuan Wang
Luis C. Ho
Mouyuan Sun
Lu Shen
Nahum Arav
Chen Chen
Qingwen Wu
Hengxiao Guo
Zesen Lin
Junyao Li
Weimin Yi
摘要： Quasar outflows may play a crucial role in regulating the host galaxy, although the spatial scale of quasar outflows remain a major enigma, with their acceleration mechanism poorly understood. The kinematic information of outflow is the key to understanding its origin and acceleration mechanism. Here, we report the galactocentric distances of different outflow components for both a sample and an individual quasar. We find that the outflow distance increases with velocity, with a typical value from several parsecs to more than one hundred parsecs, providing direct evidence for an acceleration happening at a scale of the order of 10 parsecs. These outflows carry ~1% of the total quasar energy, while their kinematics are consistent with a dust driven model with a launching radius comparable to the scale of a dusty torus, indicating that the coupling between dust and quasar radiation may produce powerful feedback that is crucial to galaxy evolution.
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： 光学 >> 量子光学 提交时间： 2023-02-19
Junyong Yan
Chen Chen
Xiao-Dong Zhang
Yu-Tong Wang
Hans-Georg Babin
Andreas D. Wieck
Arne Ludwig
Yun Meng
Xiaolong Hu
Huali Duan
Wenchao Chen
Wei Fang
Moritz Cygorek
Xing Lin
Da-Wei Wang
Chao-Yuan Jin
Feng Liu
摘要： Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gates which form the foundation of photonic quantum technologies. However, to date, coherent manipulation of quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. To break this constraint, we demonstrate an all-optical method to control high-orbital states of a hole via stimulated Auger process. The coherent nature of the Auger process is revealed by Rabi oscillation and Ramsey interference with a fidelity of 95.8%. Harnessing this coherence further enables the investigation of single-hole relaxation mechanism. A surprisingly long relaxation time (156(2) ps) is observed and explained by phonon bottleneck effect. Our work opens new possibilities for understanding the fundamental properties of high-orbital states in quantum emitters and developing new types of orbital-based quantum photonic devices.
分类： 生物学 >> 病毒学 分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2021-07-17
Chung-I Wu
Haijun Wen
Jian Lu
Xiao-dong Su
Alice C. Hughes
Weiwei Zhai
Chen Chen
Hua Chen
Mingkun Li
Shuhui Song
Zhaohui Qian
Qihui Wang
Bingjie Chen
Zixiao Guo
Yongsen Ruan
Xuemei Lu
Fuwen Wei
Li Jin
Le Kang
Yongbiao Xue
摘要： In the comparison with SARS-CoV of 2003, SARS-CoV-2 is extremely well adapted to the human populations and its adaptive shift from the animal host to humans must have been even more extensive. By the blind watchmaker argument, such an adaptive shift can only happen prior to the onset of the current pandemic and with the aid of step-by-step selection. In this view, SARS-CoV-2 could not have possibly evolved in an animal market in a big city and even less likely in a laboratory. Discussions of the origin of SARS-CoV-2 need to factor in the long process of adaptive shift and some models have indeed advanced in that direction.
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