The Central 80x200 Parsecs of M83, how Many BH and how Massive are They?

DOTTORI, H.; DIAZ, R.; RODRIGUES, I.; AGUERO, M. P.; MAST, D.

Prague, Czech Republic

Simposio; Black Holes: From Stars to Galaxies - Across the Range of Masses; 2006

International Astronomical Union

GEMINI-S+CIRPASS configuration has been used to obtain 490 spectra with a spectral resolving power of 3200, centered at 1.3 microns, oriented NW-SE and covering 110x280 pc of the central region of M83. We determine the kinematics of this region with 0.36 arcsec sampling and sub-arcsec resolution. Disk-like motions are detected in Pbeta at parsecs scales around: a) the optical nucleus b) center of the external K-band isophotes (Thatte et al, 2003) coincident with the CO velocity map (Sakamoto et al. 2004) both also tracing the center of the bulge (Jensen et al 1981). (c) a hidden condensation (Mast et al 2006), now more precisely located at (R,theta)=(158pc, 301deg). The present resolution allows to detect another whirl near the position of the blue-shifted lobe of the hidden condensation, coincident with a bright knot in the HST image. The disk around (a) has a radius of 12-18 pc and the two around (b) and (c) can be traced approximately up to 50-60 pc from their kinematical centers. The rotation curves can be fitted by Satoh like spheroids indicating masses of 2-4 E6 Msun, 10-15 E6 Msun and 15-20 E6 Msun respectively. Limit to the masses of central BHs can be set by supposing that the kinematics inside the r=9 pc central is dominated by the BH but outwards it have to respond to the BH+Satoh potential. The models were smoothed with 9 pc gaussian. The upper mass limit derived for the BH is for (a) ~10^6/seni Msun, and for (b) and (c) 2-6E5/seni Msun. Many questions arise from this interesting nucleus: 1- Are we witnessing a unique phenomenon or simply a barred galaxy with ongoing strong SF in our backyard? Does each one of the condensations host a BH? or there is only one at the bulge or kinematical center? N-body simulations show that nuclei (a), (b) and (c) will merge in 10-50 Myrs. What would happens with the putative BHs after the merge?