Circumnuclear structures in the interacting Seyfert galaxy NGC 1241 : kinematics and optical/infrared morphology

• Autor(a) principal: Díaz, Rubén Joaquín
• Data de Publicação: 2003
• Outros Autores: Dottori, Horacio Alberto, Vera Villamizar, Nelson, Carranza, Gustavo Jose
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/108909
• topic: Fotometria astronômica; Espectros astronômicos; Análise de Fourier; Nucleo galatico; Fontes de infravermelho; Galaxias seyfert; Galaxies: active; Galaxies: individual (NGC 1241); Galaxies: kinematics and dynamics; Galaxies: spiral; Galaxies: structure; Methods: numerical; Techniques: spectroscopic

We studied the spiral pattern in the inner 6".5 (1" = 257 pc) central regions of the interacting active nucleus galaxy NGC 1241 using Gemini North Telescope high-resolution Ks- and J-band images and Hubble Space Telescope (HST) Paα and H- and (V+R)-band images with high resolution in the range from ~0".1 to ~0".3 along with intermediate to large-scale spectroscopy using the Multifunction Spectrograph at the Córdoba Observatory in Argentina. Our analysis of Paα emission images revealed a faint two-armed leading spiral pattern ending in the 5".6 x 3".4 clumpy ring discovered by Böker and coworkers, harboring a 1".6 long barlike structure almost perpendicular to the large-scale bar of NGC 1241. When we applied two-dimensional Fourier analysis at circumnuclear scales, we found that a two-arm trailing mode was dominant in Ks- and J-band images while the (V+R)-band images showed more complex structural features with a strong onearmed trailing mode. One-dimensional Fourier analysis showed a corotation (CR) located outward from the edge of the Paα bar. Our kinematics data gave an angular speed ΩCN of 350±50 km s-ˡ kpc-ˡ for the trailing mode pattern. The rotation curve showed that the circumnuclear ring is located just inside the large-scale pattern inner Lindblad resonance (ILR), which has a radius of about ~1 kpc. We also found, within the uncertainties present in such measurements, that the outer Lindblad resonance (OLR) of the circumnuclear pattern is coincident with the large-scale pattern ILR, indicating a possible connection between circumnuclear and global dynamics. Nevertheless, the estimated high molecular gas fraction (≥13%) and the inner pattern high angular speed at the central region of NGC 1241 point to a nuclear bar formation via self-gravitational instability.