Ground-based Pa$\alpha$ Narrow-band Imaging of Local Luminous Infrared Galaxies II: Bulge Structure And Star Formation Activity

Abstract

We present properties of two types of bulges (classical- and pseudo- bulges) in 20 luminous infrared galaxies (LIRGs) observed in the near infrared of the $H$, $K_s$ and 1.91$\mu$m narrow-band targeting at the hydrogen Pa$\alpha$ emission line by the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope. To classify the two types of bulges, we first perform a two-dimensional bulge-disk decomposition analysis in the $K_{\mathrm{s}}$-band images. The result shows a tentative bimodal distribution of Sérsic indices with a separation at $\log (n_b)\sim 0.5$, which is consistent with that of classical and normal galaxies. We next measure extents of the distribution of star forming regions in Pa$\alpha$ emission line images, normalized with the size of the bulges, and find that they decrease with increasing Sérsic indices. These results suggest that star-forming galaxies with classical bulges have compact star forming regions concentrated within the bulges, while those with pseudobulges have extended star forming regions beyond the bulges, suggesting that there are different formation scenarios at work in classical and pseudobulges.

10 pages, 25 figures, 1 tables, accepted for publication in PASJ

References in corpus (11)

• Structural Properties of Pseudo-Bulges, Classical Bulges and Elliptical Galaxies: an SDSS Perspective
• Galaxy Merger Morphologies and Time-Scales from Simulations of Equal-Mass Gas-Rich Disc Mergers
• The Structure of Classical Bulges And Pseudobulges: The Link Between Pseudobulges And Sersic Index
• Bulge Formation by the Coalescence of Giant Clumps in Primordial Disk Galaxies
• Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation
• Near-Infrared and Star-forming properties of Local Luminous Infrared Galaxies
• The Millennium Galaxy Catalogue: The luminosity functions of bulges and discs and their implied stellar mass densities
• Formation & evolution of the Galactic bulge: constraints from stellar abundances
• The origin of pseudobulges in cosmological simulations of galaxy formation
• The Evolution of Oxygen and Magnesium in the Bulge and Disk of the Milky Way
• Stellar Population Gradients in Bulges along the Hubble Sequence: II. Relations with Galaxy Properties