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GOODS-Herschel : impact of active galactic nuclei and star formation activity on infrared spectral energy distributions at high redshift

Kirkpatrick, A.; Pope, A.; Alexander, D.M.; Charmandaris, V.; Daddi, E.; Dickinson, M.; Elbaz, D.; Gabor, J.; Hwang, H.S.; Ivison, R.; Mullaney, J.; Pannella, M.; Scott, D.; Altieri, B.; Aussel, H.; Bournaud, F.; Buat, V.; Coia, D.; Dannerbauer, H.; Dasyra, K.; Kartaltepe, J.; Leiton, R.; Lin, L.; Magdis, G.; Magnelli, B.; Morrison, G.; Popesso, P.; Valtchanov, I.

GOODS-Herschel : impact of active galactic nuclei and star formation activity on infrared spectral energy distributions at high redshift Thumbnail


Authors

A. Kirkpatrick

A. Pope

V. Charmandaris

E. Daddi

M. Dickinson

D. Elbaz

J. Gabor

H.S. Hwang

R. Ivison

J. Mullaney

M. Pannella

D. Scott

B. Altieri

H. Aussel

F. Bournaud

V. Buat

D. Coia

H. Dannerbauer

K. Dasyra

J. Kartaltepe

R. Leiton

L. Lin

G. Magdis

B. Magnelli

G. Morrison

P. Popesso

I. Valtchanov



Abstract

We explore the effects of active galactic nuclei (AGNs) and star formation activity on the infrared (0.3-1000 μm) spectral energy distributions (SEDs) of luminous infrared galaxies from z = 0.5 to 4.0. We have compiled a large sample of 151 galaxies selected at 24 μm (S 24 >~ 100 μJy) in the GOODS-N and ECDFS fields for which we have deep Spitzer IRS spectroscopy, allowing us to decompose the mid-IR spectrum into contributions from star formation and AGN activity. A significant portion (~25%) of our sample is dominated by an AGN (>50% of the mid-IR luminosity) in the mid-IR. Based on the mid-IR classification, we divide our full sample into four sub-samples: z ~ 1 star-forming (SF) sources, z ~ 2 SF sources, AGNs with clear 9.7 μm silicate absorption, and AGNs with featureless mid-IR spectra. From our large spectroscopic sample and wealth of multi-wavelength data, including deep Herschel imaging at 100, 160, 250, 350, and 500 μm, we use 95 galaxies with complete spectral coverage to create a composite SED for each sub-sample. We then fit a two-temperature component modified blackbody to the SEDs. We find that the IR SEDs have similar cold dust temperatures, regardless of the mid-IR power source, but display a marked difference in the warmer dust temperatures. We calculate the average effective temperature of the dust in each sub-sample and find a significant (~20 K) difference between the SF and AGN systems. We compare our composite SEDs to local templates and find that local templates do not accurately reproduce the mid-IR features and dust temperatures of our high-redshift systems. High-redshift IR luminous galaxies contain significantly more cool dust than their local counterparts. We find that a full suite of photometry spanning the IR peak is necessary to accurately account for the dominant dust temperature components in high-redshift IR luminous galaxies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Citation

Kirkpatrick, A., Pope, A., Alexander, D., Charmandaris, V., Daddi, E., Dickinson, M., …Valtchanov, I. (2012). GOODS-Herschel : impact of active galactic nuclei and star formation activity on infrared spectral energy distributions at high redshift. Astrophysical Journal, 759(2), Article 139. https://doi.org/10.1088/0004-637x/759/2/139

Journal Article Type Article
Publication Date Nov 1, 2012
Deposit Date Apr 8, 2013
Publicly Available Date Dec 23, 2013
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 759
Issue 2
Article Number 139
DOI https://doi.org/10.1088/0004-637x/759/2/139
Keywords Dust, Extinction, Active, Galaxies, Evolution, Star formation, Infrared.

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Copyright Statement
© 2012. The American Astronomical Society. All rights reserved. Printed in the U.S.A.





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