Optical polarization of quasars and the Balmer edge feature revealed by ultraviolet and polarized visible to near-infrared emissions

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	Optical polarization of quasars and the Balmer edge feature revealed by ultraviolet and polarized visible to near-infrared emissions
	Hu, RY; 张双南;Zhang, SN
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2012
卷号	426 期号:4 页码:2847-2858
关键词	methods: data analysis techniques: polarimetric techniques: spectroscopic galaxies: active quasars: general
英文摘要	Polarized emission from a quasar is produced by wavelength-independent electron scattering that surrounds its accretion disc. Thus, contamination from the host galaxy is avoided and the intrinsic emission spectrum of its accretion disc is revealed. Ultraviolet (UV) emission from a quasar is normally free of contamination from its host galaxy. Therefore, the polarization fraction of the quasar's disc emission can be determined by comparing the total UV emission with the polarized visible to near-infrared (NIR) emission. The resulting continuum spectrum from UV to infrared can reveal the theoretically expected Balmer edge absorption feature. We fit the polarized spectra in the visible and NIR bands, together with the total UV spectra of two type 1 quasars (3C 95 and 4C 09.72), to an extended geometrically thin and optically thick accretion disc model. In addition to the standard model, we include the Balmer edge absorption that results from corotational neutral gas on a narrow annulus of the accretion disc. We find that the extended thin accretion disc model provides an adequate description of the continuum spectra of the two quasars from UV to NIR wavelengths. A Monte CarloMarkov chain fitting to the continuum spectra is able to constrain well the true polarization fraction of the disc emission, which allows the Balmer edge feature to be completely revealed from polarized visible to UV continua. The Balmer edge feature is prominent in the spectra of both quasars, and it is significantly broadened because of the orbital motion of the gas in the accretion disc. Therefore, the broadening of the Balmer edge feature is related to the quasar's inclination. In this paper, we prove the concept of determining a quasar's inclination from the Balmer edge feature in its continuum spectra.
学科主题	Astronomy & Astrophysics
收录类别	SCI
WOS记录号	WOS:000310064400018
公开日期	2016-05-03
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/224212]
专题	高能物理研究所_粒子天体物理中心
推荐引用方式 GB/T 7714	Hu, RY,张双南；Zhang, SN. Optical polarization of quasars and the Balmer edge feature revealed by ultraviolet and polarized visible to near-infrared emissions[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2012,426(4):2847-2858.
APA	Hu, RY,&张双南；Zhang, SN.(2012).Optical polarization of quasars and the Balmer edge feature revealed by ultraviolet and polarized visible to near-infrared emissions.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,426(4),2847-2858.
MLA	Hu, RY,et al."Optical polarization of quasars and the Balmer edge feature revealed by ultraviolet and polarized visible to near-infrared emissions".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 426.4(2012):2847-2858.