Galaxy And Mass Assembly (GAMA): Spectroscopic analysis
Abstract
The Galaxy And Mass Assembly (GAMA) survey is a multiwavelength photometric and spectroscopic survey, using the AAOmega spectrograph on the Anglo-Australian Telescope to obtain spectra for up to ~300000 galaxies over 280 square degrees, to a limiting magnitude of r_pet < 19.8 mag. The target galaxies are distributed over 0<z<0.5 with a median redshift of z~0.2, although the redshift distribution includes a small number of systems, primarily quasars, at higher redshifts, up to and beyond z=1. The redshift accuracy ranges from sigma_v~50km/s to sigma_v~100km/s depending on the signal-to-noise of the spectrum. Here we describe the GAMA spectroscopic reduction and analysis pipeline. We present the steps involved in taking the raw two-dimensional spectroscopic images through to flux-calibrated one-dimensional spectra. The resulting GAMA spectra cover an observed wavelength range of 3750<lambda<8850 A at a resolution of R~1300. The final flux calibration is typically accurate to 10-20%, although the reliability is worse at the extreme wavelength ends, and poorer in the blue than the red. We present details of the measurement of emission and absorption features in the GAMA spectra. These measurements are characterised through a variety of quality control analyses detailing the robustness and reliability of the measurements. We illustrate the quality of the measurements with a brief exploration of elementary emission line properties of the galaxies in the GAMA sample. We demonstrate the luminosity dependence of the Balmer decrement, consistent with previously published results, and explore further how Balmer decrement varies with galaxy mass and redshift. We also investigate the mass and redshift dependencies of the [NII]/Halpha vs [OIII]/Hbeta spectral diagnostic diagram, commonly used to discriminate between star forming and nuclear activity in galaxies.
Keywords
Cite
@article{arxiv.1301.7127,
title = {Galaxy And Mass Assembly (GAMA): Spectroscopic analysis},
author = {A. M. Hopkins and S. P. Driver and S. Brough and M. S. Owers and A. E. Bauer and M. L. P. Gunawardhana and M. E. Cluver and M. Colless and C. Foster and M. A. Lara-Lopez and I. Roseboom and R. Sharp and O. Steele and D. Thomas and I. K. Baldry and M. J. I. Brown and J. Liske and P. Norberg and A. S. G. Robotham and S. Bamford and J. Bland-Hawthorn and M. J. Drinkwater and J. Loveday and M. Meyer and J. A. Peacock and R. Tuffs and N. Agius and M. Alpaslan and E. Andrae and E. Cameron and S. Cole and J. H. Y. Ching and L. Christodoulou and C. Conselice and S. Croom and N. J. G. Cross and R. De Propris and J. Delhaize and L. Dunne and S. Eales and S. Ellis and C. S. Frenk and A. Graham and M. W. Grootes and B. Haussler and C. Heymans and D. Hill and B. Hoyle and M. Hudson and M. Jarvis and J. Johansson and D. H. Jones and E. van Kampen and L. Kelvin and K. Kuijken and A. Lopez-Sanchez and S. Maddox and B. Madore and C. Maraston and T. McNaught-Roberts and R. C. Nichol and S. Oliver and H. Parkinson and S. Penny and S. Phillipps and K. A. Pimbblet and T. Ponman and C. C. Popescu and M. Prescott and R. Proctor and E. M. Sadler and A. E. Sansom and M. Seibert and L. Staveley-Smith and W. Sutherland and E. Taylor and L. Van Waerbeke and J. A. Vazquez-Mata and S. Warren and D. B. Wijesinghe and V. Wild and S. Wilkins},
journal= {arXiv preprint arXiv:1301.7127},
year = {2015}
}
Comments
19 pages, 19 figures, accepted for publication in MNRAS