Constraining the Accretion Rate onto Sagittarius A* Using Linear Polarization

By E. Quataert, A. Gruzinov. 2000

143 citations recorded by the source corpus.

Two possible explanations for the low luminosity of the supermassive black hole at the center of our Galaxy are (1) an accretion rate of the order of the canonical Bondi value (~10-5 M☉ yr-1) but a very low radiative efficiency for the accreting gas or (2) an accretion rate much less than the Bondi rate. Both models can explain the broadband spectrum of the Galactic center. We show that they can be distinguished using the linear polarization of synchrotron radiation. Accretion at the Bondi rate predicts no linear polarization at any frequency because of Faraday depolarization. Low accretion rate models, on the other hand, have much lower gas densities and magnetic field strengths close to the black hole; polarization may therefore be observable at high frequencies. If confirmed, a recent detection of linear polarization from Sgr A* at ≳150 GHz argues for an accretion rate of ~10-8 M☉ yr-1, much less than the Bondi rate. This test can be applied to other low-luminosity galactic nuclei.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ba01e375b6ff08ae49ea3191834e3b8cc7600f3f

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. Ramesh Narayan
2. E. Quataert
3. P. Hopkins
4. F. Yuan
5. J. McKinney
6. L. Hernquist
7. T. Johannsen
8. B. Metzger

In Nuclear and High Energy Physics

1. Ramesh Narayan
2. F. Yuan
3. J. McKinney
4. T. Johannsen
5. A. Sa̧dowski
6. J. Dexter
7. A. Tchekhovskoy
8. E. Quataert

In Statistical and Nonlinear Physics

1. Ramesh Narayan
2. L. Hernquist
3. F. Yuan
4. Heino Falcke
5. A. Broderick
6. Abraham Loeb
7. J. Dexter
8. E. Agol

Citations in the corpus

• GRMHD simulations of magnetized advection‐dominated accretion on a non‐spinning black hole: role of outflows (2012, methodology): “Analytical models of convection-dominated accretion flows (CDAFs; Narayan, Igumenshchev & Abramowicz 2000; Quataert & Gruzinov 2000b) have been developed, but their relevance to real ADAFs is unclear (see Narayan et al. 2002; Balbus & Hawley 2002 for conflicting views).”
• EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* (2010, background): “…et al. 2006) and subsequent measurements of the Faraday rotation measure (Macquart et al. 2006; Marrone et al. 2007), have implied that the accretion rate near the black hole is much less than the Bondi rate, requiring the existence of large-scale outflws (Agol 2000; Quataert & Gruzinov 2000).”
• Chandra X-Ray Spectroscopic Imaging of Sagittarius A* and the Central Parsec of the Galaxy (2001, background): “This has given rise to convection-dominated accretion flow (CDAF) models (Ball, Narayan, & Quataert 2001; Quataert & Gruzinov 2000a), in which convection transfers angular momentum inward and energy outward through the flow.”
• Fueling Low-Level AGN Activity through Stochastic Accretion of Cold Gas (2006, background): “…that such low-̇m systems are observed to be accreting substantially below the Bondi rate (Fabian & Canizares 1988; Blandford & Begelman 1999; Di Matteo et al. 2000; Narayan et al. 2000; Quataert & Gruzinov 2000; Di Matteo et al. 2001; Loewenstein et al. 2001; Bower et al. 2003; Pellegrini 2005).”
• A Concordance Picture of FRB 121102 as a Flaring Magnetar Embedded in a Magnetized Ion–Electron Wind Nebula (2018, background): “…to òp l g g» g ⎛ ⎝⎜ ⎞ ⎠⎟ ( ) e m c R R B N dRM 2 1 16 e 3 2 4 n 1 2 n n 2 where λ Rn quantifies the correlation length-scale of the magnetic field in the nebula, and the 1/γ2 correction is an approximate interpolation between the non- and ultra-relativistic regimes (Quataert & Gruzinov 2000).”
• DETECTING FLARING STRUCTURES IN SAGITTARIUS A* WITH HIGH-FREQUENCY VLBI (2008, result): “…2006), and subsequent measurements of the Faraday rotation measure (Macquart et al. 2006; Marrone et al. 2007), the accretion rate near the black hole has been inferred to be significantly less than the Bondi rate, implying the existence large-scale outflows (Agol 2000; Quataert & Gruzinov 2000).”
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole (2022, background): “Linear polarization and Faraday rotation measurements at millimeter and submillimeter (submm) wavelengths (Agol 2000; Quataert & Gruzinov 2000; Bower et al. 2003; Macquart et al. 2006; Marrone et al. 2006a, 2006b) and X-ray emission (Baganoff et al. 2003; Wang et al. 2013) combined with…”
• On the Nature of the Variable Infrared Emission from Sagittarius A* (2004, background): “…by a factor ∼ (RS/Rout) s is in good agreement with the high level of linear polarization detected at 230 GHz (e.g., Aitken et al. 2000; Bower et al. 2003), which puts an upper limit on the density of gas near the BH and thus the accretion rate onto the hole (Quataert & Gruzinov 2000; Agol 2000).”
• What controls star formation in the central 500 pc of the Galaxy (2013, background): “Alternatively, cosmic rays could originate from the activity of the central black hole of the Milky Way, which accretes at a rate of Ṁ <∼ 10−8 M⊙ yr−1 (Quataert & Gruzinov 2000; Baganoff et al. 2003).”
• Coronal outflow dominated accretion discs: a new possibility for low-luminosity black holes? (2001, background): “…inefficient flows are subject to strong convective instabilities (and might therefore be better called CDAF; Stone, Pringle & Begelman 1999, Quataert & Gruzinov 2000a), but are not in general able to generate strong outflows (although, see Misra & Taam 2001), unless the viscosty is very…”
• Neutrino-dominated Accretion and Supernovae (2005, background): “The limit s0 ¼ 0 corresponds to the original ADAF (Narayan & Yi 1994, 1995a) in which there is no outflow, while s0 ¼ 1 corresponds to the extreme limit of a convection-dominated accretion flow (CDAF; Narayan et al. 2000; Quataert & Gruzinov 2000), which deviates maximally from the ADAF.”
• THE SUBMILLIMETER BUMP IN Sgr A* FROM RELATIVISTIC MHD SIMULATIONS (2010, methodology): “Finally, our accretion rate constraint of Ṁ = 5+15 −2 × 10 −9M⊙yr −1 is consistent with but independent of estimates from the observed linear polarization and Faraday rotation measures (Agol 2000; Quataert & Gruzinov 2000; Marrone et al. 2007).”
• Accretion of Low Angular Momentum Material onto Black Holes: Two-dimensional Magnetohydrodynamic Case (2003, background): “…1982; Narayan & Yi 1995), which can fundamentally change the flow pattern and its radiative properties (Igumenshchev & Abramowicz 1999; Blandford & Begelman 1999; Stone, Pringle, & Begelman 1999; Quataert & Narayan 1999; Narayan, Igumenshchev, & Abramowicz 2000; Quataert & Gruzinov 2000).”
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A* (2003, methodology): “From Quataert & Gruzinov (2000), we have RM = e3 2πm2ec 4 ∫ dl ·Bn, for a nonrelativistic plasma, (26a) RM = e3 2πm2ec 4 ∫ dl ·Bn logγ 2γ2 , for an untrarelativistic plasma.”
• THE EVENT HORIZON OF SAGITTARIUS A* (2009, background): “…depolarized, providing some measurement of the density and magnetic field strength near the central mass. Assuming near equipartition magnetic fields, this implies a density of cold electrons of roughly 106 cm−3 at radii of 1013–1014 cm (Agol 2000; Quataert & Gruzinov 2000; Marrone et al. 2006).”