The distribution of stars around the Milky Way's central black hole II. Diffuse light from sub-giants and dwarfs

doi:10.1051/0004-6361/201730452

	The distribution of stars around the Milky Way's central black hole II. Diffuse light from sub-giants and dwarfs
	Schodel, R.1; Gallego-Cano, E.1; Dong, H.1; Nogueras-Lara, F.1; Gallego-Calvente, A. T.1; Amaro-Seoane, P.2,3,4,5,6; Baumgardt, H.7
刊名	ASTRONOMY & ASTROPHYSICS
	2018
卷号	609 页码:20
关键词	infrared: stars Galaxy: structure Galaxy: center
ISSN号	1432-0746
DOI	10.1051/0004-6361/201730452
英文摘要	Context. This is the second of three papers that search for the predicted stellar cusp around the Milky Way's central black hole, Sagittarius A, with new data and methods. Aims. We aim to infer the distribution of the faintest stellar population currently accessible through observations around Sagittarius A. Methods. We used adaptive optics assisted high angular resolution images obtained with the NACO instrument at the ESO VLT. Through optimised PSF fitting we removed the light from all detected stars above a given magnitude limit. Subsequently we analysed the remaining, diffuse light density. Systematic uncertainties were constrained by the use of data from different observing epochs and obtained with different filters. We show that it is necessary to correct for the diffuse emission from the mini-spiral, which would otherwise lead to a systematically biased light density profile. We used a Paschen alpha map obtained with the Hubble Space Telescope for this purpose. Results. The azimuthally averaged diffuse surface light density profile within a projected distance of R less than or similar to 0.5 pc from Sagittarius A* can be described consistently by a single power law with an exponent of Gamma = 0.26 +/- 0.02(stat) +/- 0.05(sys), similar to what has been found for the surface number density of faint stars in Paper I. Conclusions. The analysed diffuse light arises from sub-giant and main-sequence stars with K-s approximate to 19 22 with masses of 0.8-1.5 M-circle dot. These stars can be old enough to be dynamically relaxed. The observed power-law profile and its slope are consistent with the existence of a relaxed stellar cusp around the Milky Way's central black hole. We find that a Nuker law provides an adequate description of the nuclear cluster's intrinsic shape (assuming spherical symmetry). The 3D power-law slope near Sgr A* is gamma = 1.13 +/- 0.03(model) +/- 0.05(sys). The stellar density decreases more steeply beyond a break radius of about 3 pc, which corresponds roughly to the radius of influence of the massive black hole. At a distance of 0.01 pc from the black hole, we estimate a stellar mass density of 2.6 +/- 0.3 x 10(7) M-circle dot pc(-3) and a total enclosed stellar mass of 180 +/- 30 M circle dot. These estimates assume a constant mass-to-light ratio and do not take stellar remnants into account. The fact that a flat projected surface density is observed for old giants at projected distances R less than or similar to 0.3 pc implies that some mechanism may have altered their appearance or distribution.
资助项目	European Research Council under the European Union's Seventh Framework Programme/ERC[614922] ; Ramon y Cajal Programme of the Ministry of Economy, Industry and Competitiveness of Spain ; CAS President's International Fellowship Initiative ; Spanish Ministerio de Educacion, Cultura y Deporte[FPU14/01700] ; ESO Telescopes at the La Silla Paranal Observatory[083.B-0390] ; ESO Telescopes at the La Silla Paranal Observatory[183.B-0100] ; ESO Telescopes at the La Silla Paranal Observatory[089.B-0162]
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	EDP SCIENCES S A
WOS记录号	WOS:000418963900027
内容类型	期刊论文
源URL	[http://ir.amss.ac.cn/handle/2S8OKBNM/27057]
专题	中国科学院数学与系统科学研究院
通讯作者	Schodel, R.
作者单位	1.CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain 2.CSIC, ICE, Inst Space Sci, Campus UAB,Carrer Can Magrans S-N, Barcelona 08193, Spain 3.IEEC, Campus UAB,Carrer Can Magrans S-N, Barcelona 08193, Spain 4.Chinese Acad Sci, Acad Math & Syst Sci, Inst Appl Math, Beijing 100190, Peoples R China 5.Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China 6.TU Berlin, Zentrum Astron & Astrophys, Hardenbergstr 36, D-10623 Berlin, Germany 7.Univ Queensland St Lucia, Sch Math & Phys, St Lucia, Qld 4068, Australia
推荐引用方式 GB/T 7714	Schodel, R.,Gallego-Cano, E.,Dong, H.,et al. The distribution of stars around the Milky Way's central black hole II. Diffuse light from sub-giants and dwarfs[J]. ASTRONOMY & ASTROPHYSICS,2018,609:20.
APA	Schodel, R..,Gallego-Cano, E..,Dong, H..,Nogueras-Lara, F..,Gallego-Calvente, A. T..,...&Baumgardt, H..(2018).The distribution of stars around the Milky Way's central black hole II. Diffuse light from sub-giants and dwarfs.ASTRONOMY & ASTROPHYSICS,609,20.
MLA	Schodel, R.,et al."The distribution of stars around the Milky Way's central black hole II. Diffuse light from sub-giants and dwarfs".ASTRONOMY & ASTROPHYSICS 609(2018):20.