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Trump, Jonathan R. and Konidaris, Nicholas P. and Barro, Guillermo and Koo, David C. and Kocevski, Dale D. and Juneau, Stephanie and Weiner, Benjamin J. and Faber, S. M. and McLean, Ian S. and Yan, Renbin and Pérez González, Pablo Guillermo and Villar, Victor (2013) Testing diagnostics of nuclear activity and star formation in galaxies at z > 1. Astrophysical journal letters, 763 (1). ISSN 2041-8205
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Official URL: http://dx.doi.org/10.1088/2041-8205/763/1/L6
Abstract
We present some of the first science data with the new Keck/MOSFIRE instrument to test the effectiveness of different AGN/SF diagnostics at z ~ 1.5. MOSFIRE spectra were obtained in three H-band multi-slit masks in the GOODS-S field, resulting in 2 hr exposures of 36 emission-line galaxies. We compare X-ray data with the traditional emission-line ratio diagnostics and the alternative mass-excitation and color-excitation diagrams, combining new MOSFIRE infrared data with previous HST/WFC3 infrared spectra (from the 3D-HST survey) and multiwavelength photometry. We demonstrate that a high [O III]/Hβ ratio is insufficient as an active galactic nucleus (AGN) indicator at z > 1. For the four X-ray-detected galaxies, the classic diagnostics ([O III]/Hβ versus [N II]/Hα and [S II]/Hα) remain consistent with X-ray AGN/SF classification. The X-ray data also suggest that "composite" galaxies (with intermediate AGN/SF classification) host bona fide AGNs. Nearly ~2/3 of the z ~ 1.5 emission-line galaxies have nuclear activity detected by either X-rays or the classic diagnostics. Compared to the X-ray and line ratio classifications, the mass-excitation method remains effective at z > 1, but we show that the color-excitation method requires a new calibration to successfully identify AGNs at these redshifts.
Item Type: | Article |
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Additional Information: | © 2013 The American Astronomical Society. All rights reserved. |
Uncontrolled Keywords: | High-redshift galaxies; Digital sky survey; Mass-metallicity relation; Emission-line galaxies; Galactic nuclei; Forming galaxies; Host galaxies; Stellar mass; Black-holes; X-ray |
Subjects: | Sciences > Physics > Astrophysics Sciences > Physics > Astronomy |
ID Code: | 38433 |
Deposited On: | 06 Jul 2016 16:52 |
Last Modified: | 10 Dec 2018 15:05 |
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