Measures of the Soft X-ray Excess as an Eigenvector 1 Parameter for Active Galactic Nuclei

Journal of astrophysics and astronomy

J. Sulentic²  A. del Olmo²  K. Bensch1²  J. Perea²  P. Marziani¹ 

[1] INAF-Osservatorio Astronomico di Padova, vicolo dell′ Osservatorio 5, Padova 35122, Italy.$$;Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía, s/n,18008, Granada, Spain.$$

关键词: Galaxies: active;    quasars;    emission lines;    X-rays.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

We present a preliminary analysis of X-ray data of quasars in the context of the 4D eigenvector 1 parameter space (Sulentic et al. 2000a, b). 4DE1 serves as a surrogate H-R diagram for representing empirical diversity among quasars and identifying the physical drivers of the diversity. The soft X-ray spectral index (𝛤soft) was adopted as one of the key 4DE1 that correlates contrasting extremes in Type 1 properties. 4DE1 motivated the hypothesis of two quasar populations (A and B) divided by 𝐿/𝐿EDD ≈ 0.2. Pop. A is a largely radio-quiet population with FWHM 𝐻𝛽 < 4000 km/s and often showing a soft X-ray excess. Pop. B is a mix of radio-quiet and a majority of RL quasars shows only a hard X-ray power-law SED. The X-ray separation was based upon earlier ROSAT and ASCA data but we now confirm this dichotomy with large samples of X-ray spectra obtained with XMM-Newton and SWIFT. One popular idea connects the soft excess in Pop. A quasars as a signature of thermal emission from a hot accretion disk in sources radiating close to the Eddington limit.

【 授权许可】

Unknown