FLITECAM H-alpha Spectroscopy of the 1 Jy Gravitationally Lensed Galaxy at z=3
- Principal Investigator
- Eiichi Egami
- Proposal ID
- 05_0180
- Category
- GALAXIES
- Keywords
- IR-LUMINOUS GALAXIES
- GRAVITATIONAL LENSING
Abstract
An exceptionally bright z=3.005 gravitationally lensed submillimeter galaxy (SMG) was discovered last year using the Planck all-sky survey data. Having a peak flux density of ~1.1 Jy at ~300 microns, this SMG is by far the most luminous among many tens of similar objects discovered so far. Even taking into account the effect of lensing amplification, this galaxy must be extremely luminous intrinsically. Therefore, we would like to understand the origin and nature of this exceptional object. Here, we propose to use the FLITECAM grism spectroscopy mode to observe the redshifted H-alpha emission at z=3.005. Our main goal is to detect H-alpha emission from this galaxy and to find out (1) how much H-alpha emission is attenuated by dust (by comparing SFR(H-alpha) and SFR(LIR)), and (2) if there is any sign of a luminous AGN (e.g., a broad H-alpha component, high [N II]/H-alpha ratio). A large dust extinction (e.g., non-detection of H-alpha) would indicate that star-forming regions are concentrated in a small volume (within a few-hundred pc scale), and that the galaxy is undergoing a phase of violent starburst. On the other hand, a modest dust extinction would suggest that star-forming regions are distributed over large scales (> kpc), and that the galaxy is undergoing a phase of secular evolution (i.e., on the main-sequence of star-forming galaxies). If there is a luminous AGN harbored in this object, we should also be able to see its sign.