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

By A. Broderick, Vincent L. Fish, Sheperd S. Doeleman, Abraham Loeb. 2010

142 citations recorded by the source corpus.

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 3.9σ 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 2.9σ 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, , and east of north, where the errors quoted are the 1σ and 2σ uncertainties.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/db310f8ac292a1be9844eda6309507aa69f77edc

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. T. Johannsen
2. Ramesh Narayan
3. R. Genzel
4. F. Yuan
5. J. Dexter
6. J. McKinney
7. Dimitrios Psaltis
8. Abraham Loeb

Citations in the corpus

• PHOTON RINGS AROUND KERR AND KERR-LIKE BLACK HOLES (2013, methodology): “Especially the measurement of closure phases between the stations will allow for a highly-resolved study of the shadows and the photon rings of these sources (c.f., Broderick et al. 2011b).”
• Hot Accretion Flows Around Black Holes (2014, methodology): “From these observations some inferences have already been made on the spins of the black hole and the nature of the accretion flow and jet near the horizon (e.g., Fish et al. 2009, 2011; Broderick et al. 2009, 2011ab).”
• TESTING THE NO-HAIR THEOREM WITH EVENT HORIZON TELESCOPE OBSERVATIONS OF SAGITTARIUS A* (2013, methodology): “Here we describe the model we use for the emission region, based upon the RIAF models employed in Broderick et al. (2011b).”
• HIGH-RESOLUTION LINEAR POLARIMETRIC IMAGING FOR THE EVENT HORIZON TELESCOPE (2016, background): “…including semi-analytic radiatively inefficient accretion flow (RIAF) and jet models courtesy of Avery Broderick (Broderick & Loeb 2009; Broderick et al. 2011; Lu et al. 2014), ray-traced images from a magnetically arrested disk (see, e.g., Tchekhovskoy et al. (2011)) GRMHD simulation…”
• Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA* (2018, background): “Early estimates of the orientation of the hot gas in the innermost accretion zone based on radio data suggest a similar orientation as well (Ω ∼ 128..157◦ E. of N. (note 180◦ degeneracy), yet higher inclination i ∼ 50..68◦, Dexter et al. 2010; Broderick et al. 2011; Wang et al. 2013).”
• IPOLE - semi-analytic scheme for relativistic polarized radiative transport (2017, background): “…et al. 2007; Broderick et al. 2009; Broderick & Loeb 2009a; Dexter & Agol 2009; Mościbrodzka et al. 2009; Yuan et al. 2009; Dexter et al. 2010; Broderick et al. 2011a,b; Dexter & Fragile 2011; Vincent et al. 2011; Dexter et al. 2012; Dolence et al. 2012; Mościbrodzka et al. 2012; Younsi et…”
• The size of the jet launching region in M87 (2011, methodology): “We use the new black hole mass source structure in Sgr A* on event horizon scales (Doeleman et al. 2008; Fish et al. 2011), allowing a direct comparison between observations and black hole accretion theory (e.g., Dexter et al. 2010; Broderick et al. 2011).”