Nuclear Spirals as Signatures of Supermassive Black Holes

Abstract

Recent high resolution images of spiral galaxies show wide varieties of features including nuclear spirals in the central parts. Some of the galaxies show grand-design nuclear spirals. The morphology of grand-design spirals can be further divided by the openness of the arms: tightly wound ones with winding angle of around 3$\pi$ radian and open spirals with winding angle of around $\pi$ radian. Based on hydrodynamical simulations, we have investigated the mechanism responsible for the openness of nuclear spirals. Since the gas flow in the nuclear region is mainly governed by the central mass concentration near the nuclei and the sound speed of the gas, we have examined various models with different mass concentration represented by the mass of the central black hole and different sound speeds. We found that the tightly wound spirals can be formed when the mass of the black hole is large enough to remove the inner-inner Lindblad resonances and sound speeds lie between 15 - 20 km/sec. Thus, the presence of the tightly wound nuclear spiral could imply the presence of relatively massive black hole in the center.

6 pages, 4 figures

References in corpus (7)

• The Stellar Cusp Around the Supermassive Black Hole in the Galactic Center
• Axisymmetric Dynamical Models of the Central Regions of Galaxies
• Circumnuclear Dust in Nearby Active and Inactive Galaxies. I. Data
• Gas Inflow in Barred Galaxies - Effects of Secondary Bars
• Spiral Galaxies with HST/NICMOS. I. Nuclear Morphologies, Color Maps and Distinct Nuclei
• NGC 4314. IV. Photometry of Star Clusters with Hubble Space Telescope - History of Star Formation in the Vicinity of a Nuclear Ring
• Hydrodynamic Simulations for the Nuclear Morphology of NGC 4314

Cited by in corpus (3)

• Formation of Nuclear Spirals in Barred Galaxies
• Effect of Central Mass Concentration on the Formation of Nuclear Spirals in Barred Galaxies
• Potential-density pairs for bent bars