Intrinsic size of Sagittarius A*: 72 Schwarzschild radii

	*Intrinsic size of Sagittarius A: 72 Schwarzschild radii**
	Lo, KY ; Shen, ZQ ; Zhao, JH ; Ho, PTP
刊名	ASTROPHYSICAL JOURNAL
	1998-11-20
卷号	508 期号:1 页码:L61-L64
关键词	galaxies : active Galaxy : center scattering
英文摘要	Recent proper motion studies of stars at the very center of the Galaxy strongly suggest that Sagittarius A, the compact nonthermal radio source at the Galactic center, is a 2.5 x 10(6) M. black hole. By means of near-simultaneous multiwavelength Very Long Baseline Array measurements, we determine for the first time the intrinsic size and shape of Sgr A to be 72 R-sc(star) by less than 20 R-sc(star), with the major axis oriented essentially north-south, where R-sc(star)(= 7.5 x 10(11) cm) is the Schwarzschild radius for a 2.5 x 10(6) M. black hole. Contrary to previous expectation that the intrinsic structure of Sgr A* is observable only at lambda less than or equal to 1 mm, we can discern the intrinsic source size at lambda = 7 mm because (1) the scattering size along the minor axis is half that along the major axis and (2) the near-simultaneous multiwavelength mapping of Sgr A* with the same interferometer makes it possible to extrapolate precisely the minor axis scattering angle at lambda = 7 mm. The intrinsic size and shape place direct constraints on the various emission models for Sgr A. In particular, the advection-dominated accretion flow model may have to incorporate a radio jet in order to account for the structure of Sgr A.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	STELLAR PROPER MOTIONS ; SOURCE SGR-A ; GALACTIC-CENTER ; SCINTILLATION ; TURBULENCE ; LIMIT ; MODEL ; VLBI
收录类别	SCI
语种	英语
WOS记录号	WOS:000077780300015
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/28136]
专题	上海天文台_星系宇宙学重点实验室
作者单位	1.Acad Sinica, Inst Astron & Astrophys, Taipei 115, Taiwan 2.Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA 3.Acad Sinica, Shanghai Observ, Shanghai 200030, Peoples R China
推荐引用方式 GB/T 7714	Lo, KY,Shen, ZQ,Zhao, JH,et al. Intrinsic size of Sagittarius A*: 72 Schwarzschild radii[J]. ASTROPHYSICAL JOURNAL,1998,508(1):L61-L64.
APA	Lo, KY,Shen, ZQ,Zhao, JH,&Ho, PTP.(1998).Intrinsic size of Sagittarius A*: 72 Schwarzschild radii.ASTROPHYSICAL JOURNAL,508(1),L61-L64.
MLA	Lo, KY,et al."Intrinsic size of Sagittarius A*: 72 Schwarzschild radii".ASTROPHYSICAL JOURNAL 508.1(1998):L61-L64.