Subarcsecond 2-D photometry and spectrography of the nucleus of M31: The Supermassive black hole revisited
Sep, 1993
26 pages
Published in:
- Astron.Astrophys. 281 (1994) 691
e-Print:
- astro-ph/9309008 [astro-ph]
Report number:
- OL-36
View in:
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Abstract: (arXiv)
Sub-arcsecond imagery (HRCAM, 0".35 - 0".57 FWHM) and two-dimensional spectrography (TIGER, 0".9 FWHM) of the central nucleus of M31 have been obtained at CFHT. The photometric data clearly show the double-peaked nucleus, in excellent agreement with a recent HST image by Lauer et al. 1993. We built deconvolved surface brightness models, using the multi-Gaussian expansion method. We then perform a detailed morphological analysis of the three central photometric components (bulge, nucleus and bright secondary peak) and derive various spatial luminosity models (oblate and triaxial). Stellar velocity and velocity dispersion fields were derived from the TIGER data: the former displays an extremely rapid rotation around the true center of the galaxy, while the latter exhibits a peaked structure offset in the opposite direction of the brightest light peak. Neglecting these offsets,both extended versions of the virial theorem and detailed hydrodynamical models confirm the classical strong central mass concentration, perhaps a supermassive black hole of about 7.10**7 Msun, as well as a large excess of circular motions. These offsets, however, suggest that the nucleus presently undergoes a strong stellar oscillation, with non-stationary, non-axisymmetric dynamics. This too reopens the case for a strong central mass concentration.References(29)
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