Very Large Array Multiband Monitoring Observations of M31*

doi:10.3847/1538-4357/aa8265

	Very Large Array Multiband Monitoring Observations of M31*
	Yang, Yang 1,2; Li, Zhiyuan 1,2; Sjouwerman, Lorant O.3; Yuan, Feng 4,5; Shen, Zhi-Qiang 4,6
刊名	ASTROPHYSICAL JOURNAL
	2017-08-20
卷号	845 期号:2 页码:9
关键词	galaxies: nuclei galaxies: individual (M31) radio continuum: galaxies
ISSN号	0004-637X
DOI	10.3847/1538-4357/aa8265
通讯作者	Li, Zhiyuan(lizy@nju.edu.cn)
英文摘要	The Andromeda galaxy (M31) hosts one of the nearest and most quiescent supermassive black holes, which provides a rare, but promising opportunity for studying the physics of black hole accretion at the lowest state. We have conducted a multifrequency, multi-epoch observing campaign, using the Karl G. Jansky Very Large Array (VLA) in its extended configurations in 2011-2012, to advance our knowledge of the still poorly known radio properties of M31. For the first time, we detect M31 at 10, 15, and 20 GHz and measure its spectral index, alpha approximate to -0.45 +/- 0.08 (S-nu alpha nu(alpha)), over the frequency range of 5-20 GHz. The relatively steep spectrum suggests that the observed radio flux is dominated by the optically thin part of a putative jet, which is located at no more than a few thousand Schwarzschild radii from the black hole. On the other hand, our sensitive radio images show little evidence for an extended component, perhaps except for several parsec-scale "plumes," the nature of which remains unclear. Our data also reveal significant (a few tens of percent) flux variation of M31* at 6 GHz, on timescales of hours to days. Furthermore, a curious decrease of the mean flux density, by similar to 50%, is found between VLA observations taken during 2002-2005 and our new observations, which might be associated with a substantial increase in the mean X-ray flux of M31* starting in 2006.
WOS关键词	SUPERMASSIVE BLACK-HOLE ; ACTIVE GALACTIC NUCLEI ; SAGITTARIUS-A-ASTERISK ; X-RAY ; RADIO VARIABILITY ; NEARBY GALAXIES ; STIS SPECTROSCOPY ; M31 ; ACCRETION ; SPECTRUM
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	IOP PUBLISHING LTD
WOS记录号	WOS:000408111400026
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/22700]
专题	中国科学院紫金山天文台
通讯作者	Li, Zhiyuan
作者单位	1.Nanjing Univ, Sch Astron & Space Sci, Nanjing 210023, Jiangsu, Peoples R China 2.Nanjing Univ, Key Lab Modern Astron & Astrophys, Nanjing 210023, Jiangsu, Peoples R China 3.Natl Radio Astron Observ, Socorro, NM 87801 USA 4.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China 5.Chinese Acad Sci, Key Lab Res Galaxies & Cosmol, Beijing, Peoples R China 6.Chinese Acad Sci, Key Lab Radio Astron, Beijing, Peoples R China
推荐引用方式 GB/T 7714	Yang, Yang,Li, Zhiyuan,Sjouwerman, Lorant O.,et al. Very Large Array Multiband Monitoring Observations of M31*[J]. ASTROPHYSICAL JOURNAL,2017,845(2):9.
APA	Yang, Yang,Li, Zhiyuan,Sjouwerman, Lorant O.,Yuan, Feng,&Shen, Zhi-Qiang.(2017).Very Large Array Multiband Monitoring Observations of M31*.ASTROPHYSICAL JOURNAL,845(2),9.
MLA	Yang, Yang,et al."Very Large Array Multiband Monitoring Observations of M31*".ASTROPHYSICAL JOURNAL 845.2(2017):9.