An early-type galaxy with an inner star-forming disk
arXiv:1808.01730 · doi:10.1093/mnras/sty2008
Abstract
Early-type galaxies (ETGs) are composed of two distinct populations: high-mass and low-mass, which are likely to be built via gas-poor merging and gas-rich merging/accretion, respectively. However, it is difficult to directly associate low-mass ETGs with gas-rich processes, because currently they are gas poor with no signs of ongoing star formation. We report a discovery of an ETG (SDSS J142055.01+400715.7) with Mstellar=10^10 Msun that offers direct evidence for gas-rich merging as the origin of low-mass ETGs. The integrated properties of the galaxy are consistent with a typical low-mass ETG, but the outer and inner regions show distinct dispersion- and rotation-dominated kinematics, respectively. There are some tidal features surrounding the galaxy. These two facts suggest very recent galaxy merging. Furthermore, the inner disk harbors on-going star formation, indicating the merging to be gas rich. This type of galaxy is rare but it may be a demonstration of the role the transient phase of gas-rich merging plays in making a low-mass ETG.
arXiv comment6 pages, 6 figures, accepted for publication in MNRAS
References in corpus (15)
- The Dust Content and Opacity of Actively Star-Forming Galaxies
- The Host Galaxies of AGN
- The SAURON project -- IX. A kinematic classification for early-type galaxies
- The ATLAS3D project - III. A census of the stellar angular momentum within the effective radius of early-type galaxies: unveiling the distribution of Fast and Slow Rotators
- The Atlas3D project - XV. Benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, Fundamental Plane and Mass Plane
- The SAURON project. II. Sample and early results
- Kinemetry: a generalisation of photometry to the higher moments of the line-of-sight velocity distribution
- The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies
- The Atlas3D project - VII. A new look at the morphology of nearby galaxies: the kinematic morphology-density relation
- SDSS IV MaNGA - Spatially resolved diagnostic diagrams: A proof that many galaxies are LIERs
- Inefficient Star Formation In Extremely Metal Poor Galaxies
- The SAURON project - VIII. OASIS/CFHT integral-field spectroscopy of elliptical and lenticular galaxy centres
- The ATLAS3D project - XVII. Linking photometric and kinematic signatures of stellar discs in early-type galaxies
- The ATLAS3D Project -- XXIII. Angular momentum and nuclear surface brightness profiles
- Untangling galaxy components: full spectral bulge-disc decomposition