X-RAY RADIATION MECHANISMS AND BEAMING EFFECT OF HOT SPOTS AND KNOTS IN ACTIVE GALACTIC NUCLEAR JETS

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	X-RAY RADIATION MECHANISMS AND BEAMING EFFECT OF HOT SPOTS AND KNOTS IN ACTIVE GALACTIC NUCLEAR JETS
	Zhang J(张晋)1,2,3 ; Bai JM(白金明)1,4 ; Chen L(陈亮)1,3 ; Liang, EW5
刊名	ASTROPHYSICAL JOURNAL
	2010-02-20
卷号	710 期号:2 页码:1017-1031
关键词	galaxies: jets magnetic fields radiation mechanisms: non-thermal X-rays: galaxies
ISSN号	0004-637X
通讯作者	Zhang, J (reprint author), Chinese Acad Sci, Yunnan Observ, Natl Astron Observ, POB 110, Kunming 650011, Yunnan, Peoples R China.
产权排序	第一完成单位
英文摘要	The observed radio-optical-X-ray spectral energy distributions (SEDs) of 22 hot spots and 45 knots in the jets of 35 active galactic nuclei are complied from the literature and modeled with single-zone lepton models. It is found that the observed luminosities at 5 GHz (L(5) (GHz)) and at 1 keV (L(1) (keV)) are tightly correlated, and the two kinds of sources can be roughly separated with a division of L(1) (keV) = L(5 GHz). Our SED fits show that the mechanisms of the X-rays are diverse. While the X-ray emission of a small fraction of the sources is a simple extrapolation of the synchrotron radiation for the radio-to-optical emission, an inverse Compton (IC) scattering component is necessary to model the X-rays for most of the sources. Considering the sources at rest (the Doppler factor delta = 1), the synchrotron-self-Compton (SSC) scattering would dominate the IC process. This model can interpret the X-rays of some hot spots with a magnetic field strength (B(ssc)(delta=1)) being consistent with the equipartition magnetic field (B(eq)(delta=1)) in 1 order of magnitude, but an unreasonably low B(ssc)(delta=1) is required to model the X-rays for all knots. Measuring the deviation between B(ssc)(delta=1) and B(eq)(delta=1) with ratio R(B) equivalent to B(eq)(delta=1)/B(ssc)(delta=1), we find that R(B) is greater than 1 and it is tightly anti-correlated with ratio R(L) = L(1 keV)/L(5) (GHz) for both the knots and the hot spots. We propose that the deviation may be due to the neglect of the relativistic bulk motion for these sources. Considering this effect, the IC/cosmic microwave background (CMB) component would dominate the IC process. We show that the IC/CMB model well explains the X-ray emission for most sources under the equipartition condition. Although the derived beaming factor (delta) and co-moving equipartition magnetic field (B(eq)') of some hot spots are comparable to the knots, the delta values of the hot spots tend to be smaller and their B(eq)' values tend to be larger than that of the knots, favoring the idea that the hot spots are jet termination and knots are a part of a well-collimated jet. Both B(eq)' and delta are tentatively correlated with R(L). Corrected by the beaming effect, the L(5) (GHz)'-L(1 keV)' relations for the two kinds of sources are even tighter than the observed ones. These facts suggest that, under the equipartition condition, the observational differences of the X-rays from the knots and hot spots may be mainly due to the differences on the Doppler boosting effect and the co-moving magnetic field of the two kinds of sources. Our IC scattering models predict a prominent GeV-TeV component in the SEDs for some sources, which are detectable with H. E. S. S. and Fermi/LAT.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	HUBBLE-SPACE-TELESCOPE ; EXTRAGALACTIC RADIO-SOURCES ; MAGNETIC-FIELD STRENGTHS ; ENERGY GAMMA-RAYS ; SYNCHROTRON SPECTRA ; DEEP CHANDRA ; PICTOR-A ; M87 JET ; EMISSION ; GALAXY
收录类别	SCI
原文出处	http://iopscience.iop.org/0004-637X/710/2/1017/
语种	英语
WOS记录号	WOS:000274233300013
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5395]
专题	云南天文台_丽江天文观测站（南方基地）云南天文台_中国科学院天体结构与演化重点实验室
作者单位	1.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011, China 2.College of Physics and Electronic Engineering, Guangxi Teachers Education University, Nanning, Guangxi 530001, China 3.The Graduate School of Chinese Academy of Sciences, China 4.Key Laboratory for the Structure and Evolution of Celestial Bodies, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011, China 5.Department of Physics, Guangxi University, Nanning 530004, China
推荐引用方式 GB/T 7714	Zhang J,Bai JM,Chen L,et al. X-RAY RADIATION MECHANISMS AND BEAMING EFFECT OF HOT SPOTS AND KNOTS IN ACTIVE GALACTIC NUCLEAR JETS[J]. ASTROPHYSICAL JOURNAL,2010,710(2):1017-1031.
APA	Zhang J,Bai JM,Chen L,&Liang, EW.(2010).X-RAY RADIATION MECHANISMS AND BEAMING EFFECT OF HOT SPOTS AND KNOTS IN ACTIVE GALACTIC NUCLEAR JETS.ASTROPHYSICAL JOURNAL,710(2),1017-1031.
MLA	Zhang J,et al."X-RAY RADIATION MECHANISMS AND BEAMING EFFECT OF HOT SPOTS AND KNOTS IN ACTIVE GALACTIC NUCLEAR JETS".ASTROPHYSICAL JOURNAL 710.2(2010):1017-1031.