2018/03/06 by M. M. Pawlik, Milena M. Pawlik, Layth Taj Aldeen +14 · 1 citation
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Balmer series #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Spectral line #Star (game theory) #Star formation #astro-ph.GA
paper · pdf · doi:10.1093/mnras/sty589
Accepted by MNRAS; 19 figures, 39 pages
arxiv created 2018/03/06 · openalex publication_date 2018/03/06 · arxiv updated 2018/03/28 · openalex created_date 2018/03/29 · openalex updated_date 2026/08/05
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 <z <0.05, log(M-star/M-circle dot) > 9.5 and projected axial ratio b/a > 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 <log(M-star/M-circle dot) <10.5 and 60 per cent at log(M-star/M-circle dot) > 10.5); (2) at 9.5 <log(M-star/M-circle dot) <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(M-star/M-circle dot) > 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 'on' for 50 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 per cent incomplete due to the exclusion of narrow-line AGNs.