Analysis of the 3C 445 soft X-ray spectrum as observed by Chandra high-energy gratings

• 来源期刊: 天文和天体物理学研究
• 年，卷（期）: 2018,（5）
• 页码范围: 107-116
• 页数: 10页
• 语种: 英文
• DOI: 10.1088/1674-4527/18/5/53

摘要

We present a detailed analysis of the soft X-ray emission of 3C 445 using an archival Chandra High Energy Transmission Grating (HETG) spectrum.Highly-ionized H-and He-like Mg,Si and S lines,as well as a resolved low-ionized Si Kα line,are detected in the high resolution spectrum.The He-like triplets of Mg and Si are resolved into individual lines,and the calculated R ratios indicate a high density for the emitter.The low values of G ratios indicate the lines originate from collisionally ionized plasmas.However,the detection of a resolved narrow Ne X radiative recombination continua (RRC) feature in the spectrum seems to prefer a photoionized environment.The spectrum is subse quently modeled with a photoionization model,and the results are compared with those of a collisional model.Through a detailed analysis of the spectrum,we exclude a collisional origin for these emission lines.A one-component photoionization model provides a great fit to the emission features.The best-fit parameters are logζ=3.3+0.4+0.3 erg cms-1,nH 5+41-1.5 × 1010 cm-3 and NH =2.5+3.8-1.7 × 1020 cm-2.According to the calculated high density for the emitter,the measured velocity widths of the emission lines and the inferred radial distance (6 × 1014-8 × 1015 cm),we suggest the emission lines originating from matter are located in the broad line region (BLR).