Takagi, T.; Ohyama, Y.; Goto, T.; Matsuhara, H.; Oyabu, S.; Wada, T.; Pearson, C. P.; Lee, H. M.; Im, M.; Lee, M. G.; Shim, H.; Hanami, H.; Ishigaki, T.; Imai, K.; White, G. J.; Serjeant, S. and Malkan, M.
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|DOI (Digital Object Identifier) Link:||http://doi.org/10.1051/0004-6361/200913466|
|Google Scholar:||Look up in Google Scholar|
Aims. The NEP-deep survey, an extragalactic AKARI survey towards the north ecliptic pole (NEP), provides a comprehensive wavelength coverage from 2 to 24 μm using all 9 photometric bands of the infrared camera (IRC). It allows us to photometrically identify galaxies whose mid-IR emission is clearly dominated by PAHs.
Methods. We propose a single-colour selection method to identify such galaxies, using two mid-IR flux ratios at 11-to-7 μm and 15-to-9 μm (PAH-to-continuum flux ratio in the rest frame), which are useful for identifying starburst galaxies at z ~ 0.5 and 1,respectively. We perform a fitting of the spectral energy distributions (SEDs) from optical to mid-IR wavelengths, using an evolutionary starburst model with a proper treatment of radiative transfer (SBURT), in order to investigate their nature.
Results. The SBURT model reproduces observed optical-to-mid-IR SEDs of more than a half of the PAH-selected galaxies. Based on the 8 μm luminosity, we find ultra luminous infrared galaxies (ULIRGs) among PAH-selected galaxies. Their PAH luminosity is higher than local ULIRGs with a similar luminosity, and the PAH-to-total IR luminosity ratio is consistent with that of less luminous starburst galaxies. They are a unique galaxy population at high redshifts, and we call these PAH-selected ULIRGs "PAH-luminous" galaxies. Although they are not as massive as submillimetre galaxies at z ~ 2, they have the stellar mass of > 3 x 1010Mʘ and therefore are moderately massive.
|Item Type:||Journal Article|
|Copyright Holders:||2010 ESO|
|Extra Information:||13 pp.|
|Keywords:||starburst galaxies; infrared galaxies; active galaxies; galactic evolution|
|Academic Unit/Department:||Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Astrid Peterkin|
|Date Deposited:||10 Dec 2010 13:01|
|Last Modified:||24 Feb 2016 06:27|
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