Co-variability Between the Broad Absorption Lines and Narrow Absorption Lines

We investigate the relationship between the variability of broad absorption lines(BALs)or narrow absorption lines(NALs)and that of continuum using a data set of two-epoch SDSS spectra containing 134 C IV NAL-BAL pairs.Our analysis reveals an anti-correlation between the fractional equivalent width(EW)variations in NALs(or BALs)and the fractional flux variations of the continuum,with Spearman rank correlation coefficients of r=-0.47(p=1E-08)and r=-0.58(p=1E-13),respectively.In addition,we find a positive correlation between the fractional EW variations in NALs and BALs(r=0.72,p=1E-22),and derive a regression equation ΔEW_(NAL)/<EW_(NAL)>=0.803ΔEW_(BAL)/<EW_(BAL)>+0.008,with an intrinsic scatter of 0.14.These results suggest that the variability in the ionizing continuum may play a significant role in the observed changes in C IV NALs and BALs,supporting the idea of photoionization-driven variability.The co-variability between C IV NALs and BALs may imply that they originate from outflows with similar physical conditions.

The redshift number density evolution of Mg Ⅱ absorption systems

We make use of the recent large sample of 17 042 Mg Ⅱ absorption systems from Quider et al. to analyze the evolution of the redshift number density. Regardless of the strength of the absorption line, we find that the evolution of the redshift number density can be clearly distinguished into three different phases. In the intermediate redshift epoch （0.6 ≤ z ≤ 1.6）, the evolution of the redshift number density is consis- tent with the non-evolution curve, however, the non-evolution curve over-predicts the values of the redshift number density in the early （z ≤ 0.6） and late （z ≥ 1.6） epochs. Based on the invariant cross-section of the absorber, the lack of evolution in the red- shift number density compared to the non-evolution curve implies the galaxy number density does not evolve during the middle epoch. The fiat evolution of the redshift number density tends to correspond to a shallow evolution in the galaxy merger rate during the late epoch, and the steep decrease of the redshift number density might be ascribed to the small mass of halos during the early epoch.

Quantized Redshift and its Significance for Recent Observation

With the recent observational evidence in extragalactic astronomy,the interpretation of the nature of quasar redshift continues to be a research interest.Very high redshifts are being detected for extragalactic objects that are presumably very distant and young while also exhibiting properties that are characteristic of a more mature galaxy such as ours.According to Halton Arp and Geoffrey Burbidge,redshift disparities consist of an intrinsic component and are related to an evolutionary process.Karlsson observed redshift periodicity at integer multiples of0.089 in log scale and Burbidge observed redshift periodicity at integer multiples of 0.061 in linear scale.Since Singular Value Decomposition based periodicity estimation is known to be superior for noisy data sets,especially when the data contain multiple harmonics and overtones,mainly irregular in nature,we have chosen it to be our primary tool for analysis of the quasar-galaxy pair redshift data.We have observed a fundamental periodicity of0.051 with a confidence interval of 95%in linear scale with the site-available Sloan Digital Sky Survey Data Release 7(SDSS DR7)quasar-galaxy pair data set.We have independently generated quasar-galaxy pair data sets from both 2d F and SDSS and found fundamental periodicities of 0.077 and 0.089,respectively,in log scale with a confidence interval of 95%.

Discovery of six high-redshift quasars with the Lijiang 2.4 m telescope and the Multiple Mirror Telescope

Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.

Discovery of Balmer broad absorption lines in the quasar LBQS 1206+1052

We report the discovery of Balmer broad absorption lines （BALs） in the quasar LBQS 1206＋1052 and present a detailed analysis of the peculiar absorption line spectrum. Besides the Mg II λλ2796, 2803 doublet, BALs are also detected in the He I＊ multiplet at λλ2946, 3189, 3889 A arising from the metastable helium 2 3 S level, and in Hα and Hβ from the excited hydrogen H I＊ n = 2 level, which are rarely seen in quasar spectra. We identify two components in the BAL troughs of v ～ 2000 km s 1 width： One component shows an identical profile in H I＊, He I＊ and Mg II with its centroid blueshifted by v c ≈ 726 km s-1 . The other component is detected in He I＊ and Mg II with v c ≈ 1412 km s-1 . We estimate the column densities of H I＊, He I＊, and Mg II, and compare them with possible level population mechanisms. Our results favor the scenario that the Balmer BALs originate in a partially ionized region with a column density of N H ～ 10 21 10 22 cm-2 for an electron density of n e ～ 10 6 10 8 cm-3 via Lyα resonant scattering pumping. The harsh conditions needed may help to explain the rarity of Balmer absorption line systems in quasar spectra. With an i-band PSF magnitude of 16.50, LBQS 1206＋1052 is the brightest Balmer-BAL quasar ever reported. Its high brightness and unique spectral properties make LBQS 1206＋1052 a promising candidate for followup high-resolution spectroscopy, multi-band observations, and long-term monitoring.

Discovery of two broad absorption line quasars at redshift about 4.75 using the Lijiang 2.4 m telescope

The ultraviolet broad absorption lines have been seen in the spectra of quasars at high redshift, and are generally considered to be caused by outflows with velocities from thousands kilometers per second to one tenth of the speed of light. They provide crucial implications for the cosmological structures and physical evolutions related to the feedback of active galactic nuclei(AGNs).Recently, through a dedicated program of optically spectroscopic identifications of selected quasar candidates at redshift 5 by using the Lijiang 2.4 m telescope, we discovered two luminous broad absorption line quasars(BALQSOs) at redshift about 4.75. One of them may even have the potentially highest absorption Balnicity Index(BI) ever found to date, which is remarkably characterized by its deep, broad absorption lines and sub-relativistic outflows. Further physical properties, including the metal abundances,variabilities, evolutions of the supermassive black holes(SMBH) and accretion disks associated with the feedback process, can be investigated with multi-wavelength follow-up observations in the future.

A broad absorption line outflow associated with the broad emission line region in the quasar SDSS J075133.35+134548.3

We report on the discovery of unusual broad absorption lines(BALs)in the bright quasar SDSS J075133.35+134548.3 at z~1,using archival and newly obtained optical and NIR spectroscopic data.The BALs are detected reliably in HeⅠ*λ3889,HeⅠ*λ10830 and tentatively in AlⅢ,MgⅡ.These BALs show complex velocity structures consisting of two major components:a high-velocity component(HV),with a blueshifted velocity range ofΔv_(HV)~9300--3500 km s^(-1),which can be reliably detected in HeⅠ*λ10830,and tentatively in AlⅢand MgⅡ,whereas it is undetectable in HeⅠ*λ3889;and a low-velocity component(LV),withΔv_(LV)~3500--1800 km s^(-1),is only detected in HeⅠ*λ3889 and HeⅠ*λ10830.With the BALs from different ions,the HV outflowing gas can be constrained to have a density of nH~10^(10.3)-10^(11.4) cm^(-3),a column density of NH~10^(21) cm^(-2)and an ionization parameter of U~10^(-1.83)-10^(-1.72);inferring a distance of RHV~0.5 pc from the central continuum source with a monochromatic luminosityλLλ(5100)=7.0×10^(45)erg s^(-1)at 5100 A.This distance is remarkably similar to that of the normal broad line region(BLR)estimated from reverberation experiments,suggesting association of the BLR and the HV BAL outflowing gas.Interestingly,a blueshifted component is also detected in AlⅢand MgⅡbroad emission lines(BELs),and the AlⅢ/MgⅡof such a BEL component can be reproduced by the physical parameters inferred from the HV BAL gas.The LV BAL gas likely has a larger column density,a higher ionization level and hence a smaller distance than the HV BAL gas.Further spectroscopy with a high S/N ratio and broader wavelength coverage is needed to confirm this to shed new light on the possible connection between BALs and BELs.

The Mg_(Ⅱ)absorption line systems in quasar spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Making use of quasar spectra from LAMOST,in the spectral data around the Mg_(Ⅱ)emission lines,research described in this paper has detected 217 Mg_(Ⅱ)narrow absorption lines(NALs)with W_(r)^(λ2796)≥3σ_(w)and W_(r)^(λ2803)≥2σ_(w)in a redshift range of 0.4554≤z_(abs)≤2.1110.For quasars observed by both LAMOST and SDSS,we find that 135 Mg_(Ⅱ)NALs were obviously observed in the LAMOST spectra,347 Mg_(Ⅱ)NALs were were apparent in the SDSS spectra,and 132 Mg_(Ⅱ)NALs were clearly present in both the SDSS and LAMOST spectra.The missed Mg_(Ⅱ)NALs are likely ascribed to low signal-to-noise ratios of corresponding spectra.Among the Mg 11 NALs obviously observed in SDSS or LAMOST spectra,eight Mg 11 NALs were significantly changed with|ΔW_(r)^(λ2796)|≥3σw in time intervals ofΔMJD/(1+z_(em))=359-2819 d.

A computational method to help identify and measure metallines in high resolution QSO spectra

A computational code is developed to help identify metal absorption lines in high resolution QSO spectra, especially in the Lyα forest. The input to the code includes a list of line central wavelengths, column densities and Doppler widths. The code then searches for candidate metal absorption systems and assesses the probability that each system could be real. The framework of the strategy we employ is described in detail and we discuss how to estimate the errors in line profile fitting that are essential to identification. A series of artificial spectra is constructed to calibrate the performance of the code. Due to the effects of blending and noise on Voigt profile fitting, the completeness of the identification depends on the column density of absorbers. For intermediate and strong artificial metal absorbers, more than 90% could be confirmed by the code. The results of applying the code to the real spectra of QSOs HS0757＋5218 and Q0100＋1300 are also presented.

Origin and Properties of Strong MgII Quasar Absorption Line Systems

Strong MgII quasar absorption line systems provide us with a useful tool to understand the gas that plays an important role in galaxy formation. In this paper, placing the theories of galaxy formation in a cosmological context, we present semi-analytic models and Monte-Carlo simulations for strong MgII absorbers produced in gaseous galactic haloes and/or galaxy discs. We investigate the redshift path density for the MgII absorption lines and the properties of galaxy/absorber pairs, in particular the anti-correlation between the equivalent width of MgII absorption line and the projected galaxy-to-sightline distance. The simulated result of the mean redshift path density of strong MgII systems is consistent with the observational result. The fraction of strong MgII systems arising from galaxy disks is predicted to be ~ 10% of the total. There exists an anti-correlation between the absorption line equivalent and the projected distance of sightline to galaxy center and galaxy luminosity. We determined that the mean absorbing radius Rabs≈29 h-1 bpc(LB/LB*)0.35. After taking selection effects into consideration, this becomes Rabs ≈38 h-1 bpc(LB/LB*)0.18, which is in good agreement with the observational result. This shows the importance of considering selection effects when comparing models with observations.

Summary of a Life in Observational Ultraviolet/Optical Astronomy

I reminisce on my early life in Section 1;on my education in Sections 2 and 3;on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory(APO)in Section 7;on work on the Sloan Digital Sky Survey(SDSS) in Section 8;on work in public education in Chicago in Section 9;and on my travels in Section 10. My main science research is of an observational nature,concerning Galactic and intergalactic interstellar gas. Highlights for me included my work on the orbiting telescope Copernicus, including the discovery of interstellar deuterium;early observations of absorption associated with fivetimes ionized oxygen;and discoveries concerning the phases of gas in the local interstellar medium, based on previously unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the intergalactic cool gas using quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morphological character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many scientists were essential over many years. The conclusions developed slowly, as I moved from being a graduate student at Chicago, to a research scientist position at Princeton and then to a faculty position at Chicago. At each stage of life, I was exposed to new technologies adaptable to my science and to subsequent projects. From high school days, I encountered several management opportunities which were formative. I have been extremely fortunate both in scientific mentors I had and in experimental opportunities I encountered.

SDSS J101108+553407吸收线红移大于发射线红移的Lyα吸收系统

对于具有吸收线红移大于发射线红移的吸收体,如果吸收体具有比较大的多普勒速度,吸收体有可能是正在向类星体中心移动。在SDSS J101108+553407的光谱中认证了3个Lyα吸收体,其吸收线红移均大于发射线红移,吸收线红移分别是:3.344 2、3.349 6和3.355 3,对应的多普勒速度分别是401 km/s、773 km/s和1 166 km/s。这3个吸收体的运动情况和起源均不相同:具有最大多普勒红移的一个吸收体,可能起源于类星体物质外流的回落,而另外两个吸收体很可能起源于绕天体中心转动的云团,并且这些云团位于寄主星系中。

利用Arecibo射电望远镜河外21-cm巡天数据进行中性氢吸收线的探测研究

利用Arecibo射电望远镜40%的ALFALFA(Arecibo Legacy Fast Arecibo L-band Feed Array)河外中性氢巡天数据,探讨了进行中性氢吸收线"盲寻"的过程与方法,并给出了搜寻吸收线的一些初步结果:(1)探测到的中性氢吸收源的数量共有10个,其中5个为文献中已知源,其余新发现的吸收线源需要进一步的研究与证实.(2)利用探测灵敏度给出了探测区域中性氢柱密度的上限,这些上限的频率统计分布显示阻尼莱曼α吸收线系统(DLAs)中的中性氢气体的平均自旋温度与覆盖因子的比值Ts/f很可能大于500K.射电干扰与驻波是影响Arecibo河外中性氢吸收线探测的两个重要因素,也将进行一定的分析以及讨论相应的解决方法等.正在建设中的500 m口径射电望远镜FAST(The Five-hundred-meter Aperture Spherical Telescope)与Arecibo射电望远镜属于相似类型,但在灵敏度、频带宽度、观测天区范围等方面都将有较大的提高,结合目前的研究进展对将来FAST在中性氢吸收线方面的研究也给出了一定的展望.

证认类星体吸收线方法(英文)

提出和完善了一个分析类星体能谱数据的方法.利用该方法,可以发现并测出类星体的吸收线.文章还通过取自Sloan Digital Sky Survey样本的3个类星体的能谱数据。

引力透镜类星体SDSS J1001+5027吸收线证认

基于斯隆数字化巡天(Sloan Digital Sky Survey,SDSS)第12期数据(data release 12,DR12)的光谱,分析引力透镜类星体SDSS J1001+5027的A, B两个像的光谱。两个像光谱的红移分别为1.84132±0.00024和1.84545±0.00012,透镜天体红移约为0.415。通过证认可靠的CⅣλλ1548, 1551或Mg Ⅱλλ2796, 2803窄吸收双线的方法,证认出A, B两个像的光谱中红移分别为1.60677±0.00012, 0.87140±0.00007和0.41455±0.00006的3个吸收系统。从3个吸收系统共证认出27条窄吸收线。测量27条窄吸收线的等值宽度,再通过分析、比较3个吸收系统在A, B两个像光谱中吸收线的数量及等值宽度的差异,给出了3个吸收系统在引力透镜类星体SDSS J1001+5027视线方向可能的分布示意图。

Estimating Black Hole Masses of AGNs using Ultraviolet Emission Line Properties

Based on measured broad line region sizes in the reverberation-mapping AGN sample, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift （z 〉 0.5） AGNs. First, using the archival IUE/HST spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical relations between the BLR size and Mg Ⅱ/C Ⅳ emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mapping sample as calibration, we found two new relationships for determining the black hole mass with the full width at half maximum and the luminosity of Mg Ⅱ/C Ⅳ line. We then apply the relations to estimate the black hole masses of the AGNs in the Large Bright Quasar Survey and a sample of radio-loud quasars. For the objects with small radio-loudness, the black hole mass estimated using the RBLR-LMg Ⅱ/C Ⅳ relation is consistent with that from the RBLR-L3000 A/1350 A relation. For radio-loud AGNs, however, the mass estimated from the RBLR-LMg Ⅱ/C Ⅳ relation is systematically lower than that from the continuum luminosity L3000 A/13S0 A Because jets could have significant contributions to the UV/optical continuum luminosity of radio-loud AGNs, we emphasize once again that for radio-loud AGNs, the emission line luminosity may be a better tracer of the ionizing luminosity than the continuum luminosity, so that the relations between the BLR size and UV emission line luminosities should be used to estimate the black hole masses of high redshift radio-loud AGNs.

类星体Lyα吸收线密度与其发射线红移的关系

本文利用７２个具有中等分辨率的类星体Ｌｙα线资料，研究了Ｌｙα吸收线数密度Ｎ（Ｚａｂｓ）与类星体发射红移Ｚｅｍ的变化关系，结果表明：对于Ｚｅｍ越大的类星体其全部Ｌｙα吸收线的平均数密度Ｎ（Ｚａｂｓ）也越大，但对于相同的吸收红移值而言，Ｎ（Ｚａｂｓ）在统计意义上与Ｚｅｍ并无关系。本文还将所得结果与其他的有关工作作了比较及讨论。

从两个SDSS类星体能谱中证认出Ca Ⅱ吸收线系统(英文)

文章给出在两个SDSS类星体能谱中证认出的重金属吸收系统.对每一个吸收系统,作者探测到10个明显的重金属吸收线.这两个吸收体的红移明显小于相应类星体的红移(zabs≤ze).因此,这两个重金属吸收系统极可能与在相应类星体的视线方向上的插入星系有关.

Joint fit of Warm Absorbers in COS and HETG spectra of NGC 3783

Warm Absorbers （WAs）, as an important form of AGN outflows, show absorption in both the UV and X-ray bands. Using XSTAR generated photoionization models, for the first time we present a joint fit to the simultaneous observations of HST/COS and Chandra/HETG on NGC 3783. A total of five WAs explain well all absorption features from the AGN outflows, which are spread over a wide range of parameters： ionization parameter log~ from 0.6 to 3.8, column density logNH from 19.5 to 22.3 cm-2, velocity v from 380 to 1060 km s-1, and covering factor from 0.33 to 0.75. Not all the five WAs are consistent in pressure. Two of them are likely different parts of the same absorbing gas, and two of the other WAs may be smaller discrete clouds that are blown out from the inner region of the torus at different periods. The five WAs suggest a total mass outflowing rate within the range of 0.22-4.1 solar mass per year.

宽吸收线类星体的X-ray研究进展

本文总结最近从Ｘｒａｙ 观测得到的关于宽吸收线类星体一些新结果， 我们和人家的结果都表明吸收物质的柱密度比原来从紫外估计的高三个量级， 在ＰＧ１４１１ ＋ ４４２ 中， 我们发现Ｘｒａｙ 除了吸收成分外， 还有散射成分， 其量级和ＵＶ 吸收的剩余流量一致， 从而说明以前从ＵＶ 推断的结论是有问题的。此外， 对ＰＧ１１２６０４１ 的研究表明从宽吸收线类星体到Ｓｅｙｆｅｒｔ 星系的窄本征吸收线其物理性质是连续过渡的。