The origins of post-starburst galaxies at z < 0.05. Issue 2 (9th March 2018)

• Record Type: Journal Article
• Authors: Pawlik, M M; Taj Aldeen, L; Wild, V; Mendez-Abreu, J; Lahén, N; Johansson, P H; Jimenez, N; Lucas, W; Zheng, Y; Walcher, C J; Rowlands, K
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 477:Issue 2(2018)
• Page Start: 1708
• Page End: 1743
• Publication Date: 2018-03-09
• Subjects: galaxies: evolution -- galaxies: interactions -- galaxies: starburst -- galaxies: stellar content -- galaxies: structure; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty589
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Post-starburst galaxies can be identified via the presence of prominent Hydrogen Balmer absorption lines in their spectra. We present a comprehensive study of the origin of strong Balmer lines in a volume-limited sample of 189 galaxies with 0.01 &lt; z &lt; 0.05, $\log ({\it M}_{\star }/{\it M}_{{\odot }})&gt;9.5$ and projected axial ratio b / a &gt; 0.32. We explore their structural properties, environments, emission lines, and star formation histories, and compare them to control samples of star-forming and quiescent galaxies, and simulated galaxy mergers. Excluding contaminants, in which the strong Balmer lines are most likely caused by dust-star geometry, we find evidence for three different pathways through the post-starburst phase, with most events occurring in intermediate-density environments: (1) a significant disruptive event, such as a gas-rich major merger, causing a starburst and growth of a spheroidal component, followed by quenching of the star formation (70 per cent of post-starburst galaxies at $9.5&lt;\log (\mbox{{$M$}}_{\star }/\mbox{{$M$}}_{{\odot }})&lt;10.5$ and 60 per cent at $\log (\mbox{{$M$}}_{\star }/\mbox{{$M$}}_{{\odot }})&gt;10.5$ ); (2) at $9.5&lt;\log (\mbox{{$M$}}_{\star }/\mbox{{$M$}}_{{\odot }})&lt;10.5$, stochastic star formation in blue-sequence galaxies, causing a weak burst and subsequent return to the blue sequence (30 per cent); (3) at $\log (\mbox{{$M$}}_{\star }/\mbox{{$M$}}_{{\odot }})&gt;10.5$, cyclic evolution of quiescent galaxies which gradually move towards the high-mass end of the red sequence through weak starbursts, possibly as a result of a merger with a smaller gas-rich companion (40 per cent). Our analysis suggests that active galactic nuclei (AGNs) are &#39;on&#39; for $50\hbox{ per cent}$ of the duration of the post-starburst phase, meaning that traditional samples of post-starburst galaxies with strict emission-line cuts will be at least $50\hbox{ per cent}$ incomplete due to the exclusion of narrow-line AGNs.