Simultaneous multiwavelength observations of sagittarius A

	Simultaneous multiwavelength observations of sagittarius A
	An, T; Goss, WM ; Zhao, JH ; Hong, XY ; Roy, S ; Rao, AP ; Shen, ZQ
刊名	ASTROPHYSICAL JOURNAL
	2005-11-20
卷号	634 期号:1 页码:L49-L52
关键词	accretion black hole physics Galaxy : center radio continuum : galaxies accretion disks
通讯作者	The Astrophysical Journal
英文摘要	We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) at multiple centimeter and millimeter wavelengths on 2003 June 17. The measured flux densities of Sgr A, together with those obtained from the Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are used to construct a simultaneous spectrum of Sgr A from 90 cm to 3.8 mu m. The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible signature of synchrotron self-absorption of the strong radio outburst that occurred near epoch 2003 July 17. At 90 cm, the flux density of Sgr A* is 0.22 +/- 0.06 Jy, suggesting a sharp decrease in flux density at wavelengths longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent with free-free absorption by a screen of ionized gas with a cutoff similar to 100 cm. This cutoff wavelength appears to be three times longer than that of similar to 30 cm suggested by Davies, Walsh, & Booth based on observations in 1974 and 1975. Our analysis suggests that the flux densities of Sgr A* at wavelengths longer than 30 cm could be attenuated and modulated by stellar winds from massive stars close to Sgr A*.
学科主题	射电天文学
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	SUPERMASSIVE BLACK-HOLE ; GALACTIC-CENTER ; SUBMILLIMETER ARRAY ; 1 MILLIMETER ; MILKY-WAY ; ASTERISK ; RADIO ; SPECTRUM ; VARIABILITY ; CENTIMETER
收录类别	SCI
语种	英语
WOS记录号	WOS:000233348100013
公开日期	2010-04-29
内容类型	期刊论文
源URL	[http://119.78.226.72//handle/331011/8021]
专题	上海天文台_VLBI研究室
作者单位	1.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China 2.Natl Radio Astron Observ, Socorro, NM 87801 USA 3.Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA 4.Natl Ctr Radio Astrophys, TIFR, Pune 411007, Maharashtra, India
推荐引用方式 GB/T 7714	An, T,Goss, WM,Zhao, JH,et al. Simultaneous multiwavelength observations of sagittarius A[J]. ASTROPHYSICAL JOURNAL,2005,634(1):L49-L52.
APA	An, T.,Goss, WM.,Zhao, JH.,Hong, XY.,Roy, S.,...&Shen, ZQ.(2005).Simultaneous multiwavelength observations of sagittarius A.ASTROPHYSICAL JOURNAL,634(1),L49-L52.
MLA	An, T,et al."Simultaneous multiwavelength observations of sagittarius A".ASTROPHYSICAL JOURNAL 634.1(2005):L49-L52.