Abstract Based on a sample of 79 local advanced merger (adv-merger) (U)LIRGs, we search for evidence of quenching processes by investigating the distributions of star formation history indicators (EW(Hα), EW(HδA) and Dn(4000)) on the NUV-r color-mass and SFR-M∗ diagrams. The distributions of EW(Hα) and Dn(4000) on the NUV-r color-mass diagram show clear trends that at a given stellar mass, galaxies with redder NUV-r colors have smaller EW(Hα) and larger Dn(4000). The reddest adv-merger (U)LIRGs close to the green valley mostly have Dn(4000)> 1.4. In addition, in the SFR-M∗ diagram, as the SFR decreases, the EW(Hα) decreases and the Dn (4000) increases, implying that the adv-merger (U)LIRGs on the star formation main sequence have more evolved stellar populations than those above the main sequence. These results indicate that a fraction of the adv-merger (U)LIRGs have already exhibited signs of fading from the starburst phase and that the NUV-r reddest adv-merger (U)LIRGs are likely at the initial stage of post-starbursts with an age of ~1 Gyr, which is consistent with the gas exhaustion time-scales. Therefore, our results offer additional support for the fast evolutionary track from the blue cloud to the red sequence.
Keywords galaxies: evolution — galaxies: formation — galaxies: interactions — galaxies: starburst — infrared: galaxies
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