The Southern 2MASS Active Galactic Nuclei Survey: Spectroscopic Follow-up with Six Degree Field
Abstract
The Two Micron All-Sky Survey (2MASS) has provided a uniform photometric catalog to search for previously unknown red active galactic nuclei (AGN) and Quasi-Stellar Objects (QSOs). We have extended the search to the southern equatorial sky by obtaining spectra for 1182 AGN candidates using the six degree field (6dF) multifibre spectrograph on the UK Schmidt Telescope. These were scheduled as auxiliary targets for the 6dF Galaxy Redshift Survey. The candidates were selected using a single color cut of J – K_s > 2 to K_s ≾ 15.5 and a galactic latitude of |b| > 30°. 432 spectra were of sufficient quality to enable a reliable classification. 116 sources (~27%) were securely classified as type I AGN, 20 as probable type I AGN, and 57 as probable type II AGN. Most of them span the redshift range 0.05 < z < 0.5 and only 8 (~6%) were previously identified as AGN or QSOs. Our selection leads to a significantly higher AGN identification rate amongst local galaxies (>20%) than in any previous (mostly blue-selected) galaxy survey. A small fraction of the type I AGN could have their optical colors reddened by optically thin dust with A_V < 2 mag relative to optically selected QSOs. A handful show evidence of excess far-infrared (IR) emission. The equivalent width (EW) and color distributions of the type I and II AGN are consistent with AGN unified models. In particular, the EW of the [OIII] emission line weakly correlates with optical–near-IR color in each class of AGN, suggesting anisotropic obscuration of the AGN continuum. Overall, the optical properties of the 2MASS red AGN are not dramatically different from those of optically-selected QSOs. Our near-IR selection appears to detect the most near-IR luminous QSOs in the local universe to z ≃ 0.6 and provides incentive to extend the search to deeper near-IR surveys.
Additional Information
© 2010 Astronomical Society of Australia. Received 2010 January 10, accepted 2010 May 12. Published: 2 September 2010. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is http://www.sdss.org/. This research has made use of the NASA/IPAC Extragalactic Database (NED) and the NASA/IPAC Infrared Science Archive (IRSA), which are operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The 6dFGS was carried out by the Anglo-Australian Observatory and the 6dFGS team (http://www.aao.gov.au/local/ www/6df/6dFGSteam.html), who have all contributed to the work presented here. This work was carried out at the California Institute of Technology, with funding from the National Aeronautics and Space Administration. RMC acknowledges support from the National Academy of Sciences James Craig Watson Medal award. JPH was supported in part by NSF Grant AST0406906. We thank the anonymous referee for helpful comments. Facilities: CTIO:2MASS, UKST (6dF).Additional details
- Eprint ID
- 20553
- Resolver ID
- CaltechAUTHORS:20101027-090634050
- NASA
- AST-0406906
- NSF
- Alfred P. Sloan Foundation
- Department of Energy (DOE)
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- National Academy of Sciences
- Created
-
2010-12-01Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)