Are the jets accelerated from the disk coronas in some active galactic nuclei?

	Are the jets accelerated from the disk coronas in some active galactic nuclei?
	Cao, XW
刊名	ASTROPHYSICAL JOURNAL
	2004-10-01
卷号	613 期号:2 页码:716-724
关键词	accretion black hole physics galaxies : active galaxies : jets accretion disks
英文摘要	We use a sample of radio-loud active galactic nuclei (AGNs) with estimated central black hole masses to explore AGN jet-formation mechanisms. The jet power of AGNs is estimated from their extended radio luminosity. We find that the jets in several AGNs of this sample are too powerful to be extracted from the standard thin accretion disks or rapidly spinning black holes surrounded by standard thin disks. If advection-dominated accretion flows (ADAFs) are present in these AGNs, their bright optical continuum luminosity cannot be produced by pure ADAFs because of their low accretion rates and low radiation efficiency, unless the ADAFs transit to standard thin disks at some radii R-tr. If this is the case, we find that dimensionless accretion rates (m) over dot = (M) over dot/(M) over dot(Edd) as high as greater than or equal to 0.05, and a transition from ADAFs to standard thin disks at rather small radii, similar to 20GM(bh)/c(2), are required to explain their bright optical continuum emission. We propose that the disk-corona structure is present in at least some AGNs in this sample. The plasmas in the corona are very hot, and the pressure scale height of the corona H-c similar to R. Powerful jets with Q(jet) similar to L-bol (bolometric luminosity) can form via the large-scale magnetic fields created by dynamo processes in the disk corona of some AGNs. The maximal jet power extractable from the corona, Q(jet)(max) less than or equal to 0.6L(c) (L-c is the corona luminosity), is expected in this jet-formation scenario. The statistical results for the sample of AGNs are consistent with the predictions of this scenario. Finally, the possibility that the jet is driven from a super-Keplerian rotating hot layer located between the corona and the cold disk is discussed. We find that, in principle, this layer could also produce a powerful jet with Q(jet) similar to L-bol.
学科主题	星系和宇宙学研究中心
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	DOMINATED ACCRETION FLOWS ; RADIO-LOUD QUASARS ; BLANDFORD-ZNAJEK MECHANISM ; BL LACERTAE OBJECTS ; BLACK-HOLE MASSES ; ELECTROMAGNETIC EXTRACTION ; ROTATIONAL ENERGY ; SEYFERT-GALAXIES ; SPECTRAL MODELS ; EXTENDED RADIO
收录类别	SCI
语种	英语
WOS记录号	WOS:000224303200008
公开日期	2010-11-08
内容类型	期刊论文
源URL	[http://119.78.226.72//handle/331011/12427]
专题	上海天文台_星系宇宙学重点实验室
作者单位	Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China
推荐引用方式 GB/T 7714	Cao, XW. Are the jets accelerated from the disk coronas in some active galactic nuclei?[J]. ASTROPHYSICAL JOURNAL,2004,613(2):716-724.
APA	Cao, XW.(2004).Are the jets accelerated from the disk coronas in some active galactic nuclei?.ASTROPHYSICAL JOURNAL,613(2),716-724.
MLA	Cao, XW."Are the jets accelerated from the disk coronas in some active galactic nuclei?".ASTROPHYSICAL JOURNAL 613.2(2004):716-724.