Connecting the X-ray properties of weak-line and typical quasars: testing for a geometrically thick accretion disk

被引:49
作者
Ni, Q. [1 ]
Brandt, W. N. [1 ,2 ,3 ]
Luo, B. [4 ,5 ]
Hall, P. B. [6 ]
Shen, Yue [7 ]
Anderson, S. F. [8 ]
Plotkin, R. M. [9 ]
Richards, Gordon T. [10 ]
Schneider, D. P. [1 ,2 ]
Shemmer, O. [11 ]
Wu, Jianfeng [12 ]
机构
[1] Penn State Univ, Dept Astron & Astrophys, Davey Lab, 525 Davey Lab, University Pk, PA 16802 USA
[2] Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA
[3] Penn State Univ, Dept Phys, 104 Davey Lab, University Pk, PA 16802 USA
[4] Nanjing Univ, Sch Astron & Space Sci, Nanjing 210093, Jiangsu, Peoples R China
[5] Nanjing Univ, Minist Educ, Key Lab Modern Astron & Astrophys, Nanjing 210093, Jiangsu, Peoples R China
[6] York Univ, Dept Phys & Astron, 4700 Keele St, Toronto, ON M3J 1P3, Canada
[7] Univ Illinois, Dept Astron, Urbana, IL 61801 USA
[8] Univ Washington, Dept Astron, Box 351580, Seattle, WA 98195 USA
[9] Curtin Univ, Int Ctr Radio Astron Res, GPO Box U1987, Perth, WA 6845, Australia
[10] Drexel Univ, Dept Phys, 32 S 32nd St, Philadelphia, PA 19104 USA
[11] Univ North Texas, Dept Phys, Denton, TX 76203 USA
[12] Xiamen Univ, Dept Astron, Xiamen 361005, Fujian, Peoples R China
基金
国家重点研发计划; 加拿大自然科学与工程研究理事会; 中国国家自然科学基金;
关键词
galaxies: active; galaxies: nuclei; quasars: general; X-rays: galaxies; DIGITAL SKY SURVEY; ACTIVE GALACTIC NUCLEI; BLACK-HOLE MASS; EDDINGTON RATIO; DATA RELEASE; ULTRAVIOLET EXTINCTION; SPECTRAL PROPERTIES; GENERAL-RELATIVITY; RADIATION PRESSURE; CONFIDENCE-LIMITS;
D O I
10.1093/mnras/sty1989
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present X-ray and multiwavelength analyses of 32 weak emission-line quasars (WI,Qs) selected in a consistent and unbiased manner. New Chandra 3.1-4.8 ks observations were obtained for 14 of these WLQs with C IV rest-frame equivalent widths (REWs) of 5-15 angstrom, and these serve as an X-ray observational "bridge" between previously studied WLQ5 with C IV REW less than or similar to 5 angstrom and more-typical quasars with C IV REW approximate to 15-100 angstrom. We have identified and quantified a strong dependence of the fraction of X-ray weak quasars upon C IV REW; this fraction declines by a factor of approximate to 13 (from approximate to 44% to approximate to 3%) for C IV REW ranging from 4 to 50 angstrom, and the rate of decline appears particularly strong in the 10-20 angstrom range. The dependence broadly supports the proposed "shielding" model for WLQs, in which a geometrically and optically thick inner accretion disk, expected for a quasar accreting at a high Eddington ratio, both prevents ionizing EUV/X-ray photons from reaching the high-ionization broad emission-line region and also sometimes blocks the line of sight to the central X-ray-emitting region. This model is also supported by the hard average spectral shape of X-ray weak WLQs (with a power-law effective photon index of Gamma(eff) = 1.19(-0.45)(+0.562)). Additionally, we have examined ultraviolet (UV) continuum/emission-line properties that might trace X-ray weakness among WLQs, confirming that red UV continuum color is the most-effective tracer.
引用
收藏
页码:5184 / 5202
页数:19
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