Integral Field Spectroscopy of a Candidate Disk Galaxy at z ~ 1.5 Using Laser Guide Star Adaptive Optics
Abstract
We present 0.1" resolution near-infrared integral field spectroscopy of Hα in a z=1.4781 star-forming galaxy, Q2343-BM133. These observations were obtained with the OH Suppressing Infra-Red Imaging Spectrograph (OSIRIS) using the W. M. Keck Observatory laser guide star adaptive optics (LGS AO) system. Hα emission is resolved over a 0.8''(6.8 kpc)×0.5''(4.3 kpc) region with a 0.1" spatial resolution. We find a global flux of 4.2+/-0.6×10-16 ergs s-1 cm-2, and detect a spatially resolved velocity gradient of ~134 km s-1 across the galaxy and a global velocity dispersion of 73+/-9 km s-1. An upper limit of [N II]/Hα<~0.12 is inferred, which implies that this galaxy is not dominated by an active galactic nucleus and has a metallicity at or below 1/2 solar metallicity. We derive a star formation rate (SFR) of 47+/-6 Msolar yr-1 and a dereddened SFR of 66+/-9 Msolar yr-1. Two-dimensional kinematics for Q2343-BM133 fit well with an inclined disk model, with which we estimate an enclosed mass of 4.3×109 Msolar within 5.5 kpc. A possible merger scenario is also presented, and cannot be fully ruled out. We derive a virial mass of 1.1×1010 Msolar for a disk geometry, using the observed velocity dispersion. We propose that Q2343-BM133 is currently at an early stage of disk formation at a look-back time of 9.3 Gyr.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2007
- DOI:
- 10.1086/511632
- arXiv:
- arXiv:astro-ph/0612199
- Bibcode:
- 2007ApJ...658...78W
- Keywords:
-
- Galaxies: Evolution;
- Galaxies: High-Redshift;
- Galaxies: Kinematics and Dynamics;
- Infrared: Galaxies;
- Astrophysics
- E-Print:
- 21 pages, 5 figures, ApJ accepted