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arXiv · 0801.0127

A UV study of nearby luminous infrared galaxies: star formation histories and the role of AGN

Sugata Kaviraj
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Abstract

We employ UV and optical photometry, from the GALEX and SDSS surveys respectively, to study the star formation histories of 561 luminous infrared galaxies (LIRGs) in the nearby Universe. A small fraction (~4%) of these galaxies have spheroidal or near-spheroidal morphologies and could be progenitors of elliptical galaxies. The remaining galaxies are morphologically late-type or ongoing mergers. 61% of the LIRGs do not show signs of interactions, while the remaining objects are either interacting (~18%) or show post-merger morphologies (~19%). The (SSP-weighted) average age of the underlying stellar populations in these objects is typically 5-9 Gyrs, with a mean value of ~6.8 Gyrs. ~60% of the LIRG population began their recent star formation (RSF) episode within the last Gyr, while the remaining objects began their RSF episodes 1 to 3 Gyrs in the past. Up to 35% of the stellar mass in the remnant forms in these episodes - the mean value is ~15%. The (decay) timescales of the star formation are typically a few Gyrs, indicating that the star formation rate does not decline significantly during the course of the burst. 14% of the LIRG population host (Type 2) AGN. The AGN hosts exhibit UV and optical colours that are redder than those of the normal (non-AGN) population. However, there is no evidence for a systematically higher dust content in the AGN hosts. AGN typically appear ~0.5-0.7 Gyrs after the onset of star formation and the redder colours are a result of older RSF episodes, with no measurable evidence of negative feedback from the AGN on the star formation in their host galaxies. (abridged)

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Sugata Kaviraj. 2009-02-20. A UV study of nearby luminous infrared galaxies: star formation histories and the role of AGN. https://doi.org/10.1111/j.1365-2966.2009.14399.x

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