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 two hour 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 [OIII]/Hb
ratio is insufficient as an AGN indicator at z>1. For the four X-ray detected
galaxies, the classic diagnostics ([OIII]/Hb vs. [NII]/Ha and [SII]/Ha) 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.Comment: 7 pages, 4 figures. Accepted to ApJ Letter

Barro, Guillermo

Faber, S. M.

Juneau, Stephanie

Kocevski, Dale D.

Konidaris, Nicholas P.

Koo, David C.

McLean, Ian S.

Perez-Gonzalez, Pablo G.

Trump, Jonathan R.

Villar, Victor

Weiner, Benjamin J.

Yan, Renbin

The Astrophysical Journal

English

arXiv

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 \u3e 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 \u3e 1, but we show that the color-excitation method requires a new calibration to successfully identify AGNs at these redshifts

Juneau, Stéphanie

Pérez-González, Pablo G.

University of Kentucky

Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies at \u3cem\u3ez\u3c/em\u3e \u3e 1

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

Caltech Authors - Main

Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies at z > 1

© 2013 The American Astronomical Society. All rights reserved. 
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. Also based on data obtained at the W. M. Keck Observatory, made possible by the generous financial support of the W. M. Keck Foundation and operated as a scientific partnership among Caltech, the University of California, and NASA. J.R.T. and the authors from UCSC acknowledge support from NASA HST grants GO-12060.10-A and AR-12822.03, Chandra grant G08-9129A, and NSF grant AST-0808133. N.P.K. acknowledges support from NSF grant AST-1106171. This work uses data from the 3-D HST Treasury Survey (Program ID 12177). We owe tremendous gratitude to the MOSFIRE commissioning team for development and support of a spectacular instrument. We also thank Greg Wirth, Marc Kassis, Jim Lyke, and the staff of Keck observatory for excellent support while observing. We wish to recognize and acknowledge the very significant cultural role that the summit of Mauna Kea has within the indigenous Hawaiian community: we are fortunate to have the opportunity to conduct observations from this mountain.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.National Aeronautics and Space Administration (NASA)W. M. Keck FoundationHubble Space Telescope (HST)-NASA GrantsChandra (NASA)National Science Foundation (NSF)Depto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu

Pérez González, Pablo Guillermo

Docta Complutense

Testing diagnostics of nuclear activity and star formation in galaxies at z > 1

Jonathan R. Trump

Nicholas P. Konidaris

Guillermo Barro

David C. Koo

Dale D. Kocevski

Stéphanie Juneau

Benjamin J. Weiner

S. M. Faber

Ian S. McLean

Renbin Yan

Pablo G. Pérez-González

Victor Villar

Crossref

TESTING DIAGNOSTICS OF NUCLEAR ACTIVITY AND STAR FORMATION IN GALAXIES AT
                    <i>z</i>
                    &gt; 1

https://authors.library.caltech.edu/37005/1/2041-8205_763_1_L6.pdf

Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies
  at z>1

Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies at z>1

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Docta Complutense

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