What Is the Accretion Rate in NGC 4258?
Abstract
We estimate the accretion rate M onto the black hole in the nucleus of NGC 4258. The result is model dependent. We find that a thin disk that is flat out to ≳2 × 10^3GM/c^2 (M ≡ black hole mass) and that has inclination equal to that of the masing disk must have M ≃ 0.01 M☉ yr^(-1) for consistency with near-infrared data. A thin disk that is warped at ~103GM/c2 requires M ≳ 1.5 × 10^(-4) M☉ yr^(-1) for consistency with near-infrared data. Reasonable warp models and the near-infrared data are not consistent with M as low as the 7 × 10^(-5) α M☉ yr^(-1) proposed by Neufeld & Maloney. An advection-dominated flow model combined with the X-ray data implies M ≃ 0.01 M☉ yr^(-1). Consistency with a tight 22 GHz upper limit on the flux from the central source requires a transition radius of ~(10-100)GM/^c2, although the 22 GHz upper limit may be relaxed by appeal to free-free absorption. Physical conditions in the observed VLBI jet features can also be related to conditions in the inner accretion flow. We conclude with a list of observations that might further constrain M.
Additional Information
© 1999 The American Astronomical Society. Received 1998 June 26; accepted 1998 December 8. This work was supported in part by NSF grants AST 94-23209 and AST 95-29170 and NASA grants NAG 5-2837 and NAG5-7007. We thank A. Esin for assistance with the ASCA data, and R. Chary, L. Greenhill, J. Herrnstein, J.-P. Lasota, and the referee for helpful comments.Attached Files
Published - Gammie_1999_ApJ_516_177.pdf
Submitted - 9808036.pdf
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Additional details
- Eprint ID
- 96031
- Resolver ID
- CaltechAUTHORS:20190603-095044083
- NSF
- AST 94-23209
- NSF
- AST 95-29170
- NASA
- NAG 5-2837
- NASA
- NAG5-7007
- Created
-
2019-06-03Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- TAPIR