EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A*

被引:144
作者
Broderick, Avery E. [1 ]
Fish, Vincent L. [2 ]
Doeleman, Sheperd S. [2 ]
Loeb, Abraham [3 ]
机构
[1] Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada
[2] MIT, Haystack Observ, Westford, MA 01886 USA
[3] Harvard Univ, Ctr Astrophys, Inst Theory & Computat, Cambridge, MA 02138 USA
基金
美国国家科学基金会;
关键词
accretion; accretion disks; black hole physics; Galaxy: center; submillimeter: general; techniques: interferometric; LINEAR-POLARIZATION; GALACTIC-CENTER; EMISSION; SIMULATIONS; HORIZON; RADIO; JETS; FLOW; RADIATION; ROTATION;
D O I
10.1088/0004-637X/735/2/110
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Millimeter very long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, this provides access to the region in the immediate vicinity of the horizon. Broderick et al. have already shown that by leveraging spectral and polarization information as well as accretion theory, it is possible to extract accretion-model parameters (including black hole spin) from mm-VLBI experiments containing only a handful of telescopes. Here we repeat this analysis with the most recent mm-VLBI data, considering a class of aligned, radiatively inefficient accretion flow (RIAF) models. We find that the combined data set rules out symmetric models for Sgr A*'s flux distribution at the 3.9 sigma level, strongly favoring length-to-width ratios of roughly 2.4:1. More importantly, we find that physically motivated accretion flow models provide a significantly better fit to the mm-VLBI observations than phenomenological models, at the 2.9 sigma level. This implies that not only is mm-VLBI presently capable of distinguishing between potential physical models for Sgr A*'s emission, but further that it is sensitive to the strong gravitational lensing associated with the propagation of photons near the black hole. Based upon this analysis we find that the most probable magnitude, viewing angle, and position angle for the black hole spin are a = 0.0(+0.64+0.86), theta = 68 degrees(+5 degrees+9 degrees)(-20 degrees-28 degrees), and xi = -52 degrees(+17 degrees+33 degrees)(-15 degrees-24 degrees) east of north, where the errors quoted are the 1 sigma and 2 sigma uncertainties.
引用
收藏
页数:15
相关论文
共 57 条
[1]   Sagittarius A* polarization: No advection-dominated accretion flow, low accretion rate, and nonthermal synchrotron emission [J].
Agol, E .
ASTROPHYSICAL JOURNAL, 2000, 538 (02) :L121-L124
[2]  
Aitken DK, 2000, ASTROPHYS J, V534, pL173, DOI 10.1086/312685
[3]   The influence of magnetic field geometry on the evolution of black hole accretion flows: Similar disks, drastically different jets [J].
Beckwith, Kris ;
Hawley, John F. ;
Krolik, Julian H. .
ASTROPHYSICAL JOURNAL, 2008, 678 (02) :1180-1199
[4]   On the fate of gas accreting at a low rate on to a black hole [J].
Blandford, RD ;
Begelman, MC .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1999, 303 (01) :L1-L5
[5]   Interferometric detection of linear polarization from Sagittarius A* at 230 GHz [J].
Bower, GC ;
Wright, MCH ;
Falcke, H ;
Backer, DC .
ASTROPHYSICAL JOURNAL, 2003, 588 (01) :331-337
[6]   BIMA observations of linear polarization in Sagittarius A* at 112 GHz [J].
Bower, GC ;
Wright, MCH ;
Falcke, H ;
Backer, DC .
ASTROPHYSICAL JOURNAL, 2001, 555 (02) :L103-L106
[7]   The intrinsic size of Sagittarius A* from 0.35 to 6 cm [J].
Bower, Geoffrey C. ;
Goss, W. M. ;
Falcke, Heino ;
Backer, Donald C. ;
Lithwick, Yoram .
ASTROPHYSICAL JOURNAL, 2006, 648 (02) :L127-L130
[8]   Covariant magnetoionic theory - II. Radiative transfer [J].
Broderick, A ;
Blandford, R .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2004, 349 (03) :994-1008
[9]   Imaging optically-thin hotspots near the black hole horizon of Sgr A* at radio and near-infrared wavelengths [J].
Broderick, AE ;
Loeb, A .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2006, 367 (03) :905-916
[10]   Frequency-dependent shift in the image centroid of the black hole at the galactic center as a test of general relativity [J].
Broderick, AE ;
Loeb, A .
ASTROPHYSICAL JOURNAL, 2006, 636 (02) :L109-L112