The central 80×200 pc of M83: how many black holes and how massive are they?

Abstract

The central ≈ 80 × 200 pc of the barred spiral galaxy M83 (NGC 5236) has been observed with the GEMINI-S+CIRPASS configuration which produced 490 spectra with a spectral resolving power of 3200, centered at 1.3 microns, oriented NW-SE. We determine the kinematics of this region with 0.36 sampling and sub-arcsec resolution. Disk-like motions have been detected in Paβ at parsec scales around: a) the optical nucleus, b) the center of the external K-band isophotes coincident with that of the CO velocity map both also tracing the center of the bulge, and c) a hidden condensation located at (R,θ)=(158pc, 301 o ). The present resolution allows to detect other minor whirls, not discussed here. The disk around (a) has a radius of ∼ 8 pc and the two around (b) and (c) can be traced approximately up to 50-60 pc from their kinematical centers.The rotation curves have been fitted by Satoh like spheroids+disk indicating masses of ≈4 × 10 6 M , 60-70 × 10 6 M and 30-40 × 10 6 M respectively. Limit to the masses of central BHs can be set by supposing that the central unresolved line broadening inside each condensations is dominated by the BH as far as allowed by the central error bars. The BH+Satoh models were smoothed with a 9 pc Gaussian. The upper mass limit derived for the BH is for (a) ∼ 10 6 / sin(i)M , and for (b) and (c) 0.2-1.0×10 6 / sin(i)M . Many questions arise from this interesting nucleus: 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 indeed? or is there only one at the bulge center? Which is the fate of this complex scenario?

The secular evolution of M83 central bulge

“…The masses derived by Dottori et al (2007) are ≈4×10 6 M , 60-70×10 6 M and 30-40×10 6 M , respectively. Upper mass limit for putative BH associated to each one of the condensations are (ON) ∼ 10 6 / sin(i) M , and for (KC) and (HN) 0.2-1.0×10 6 / sin(i) M .…”

“…KC shows an inclination of 68 • ± 10 • and the HN inclination is 50 • ± 10 • . The masses derived by Dottori et al (2007) are ≈4×10 6 M , 60-70×10 6 M and 30-40×10 6 M , respectively.…”

“…The kinematics at the bulge center was studied at excellent conditions and with high spatial resolution 2-D spectroscopy with CIRPASS, (Parry et al 2004) installed on the GEMINI-S telescope in March 2003. The IFU data, (partially presented by Dottori et al 2007) have got a sampling of 0.36 (7.8 pc) in an elliptical array with size 4.7 × 13 .…”