High-velocity outflows persist up to 1 Gyr after a starburst in recently quenched galaxies at z > 1

Elizabeth Taylor*, David Maltby, Omar Almaini, Michael Merrifield, Vivienne Wild, Kate Rowlands, Jimi Harrold

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

High-velocity outflows are ubiquitous in star-forming galaxies at cosmic noon, but are not as common in passive galaxies at the same epoch. Using optical spectra of galaxies selected from the UKIDSS Ultra Deep Survey at z > 1, we perform a stacking analysis to investigate the transition in outflow properties along a quenching time sequence. To do this, we use Mg ii (λ2800 Å) absorption profiles to investigate outflow properties as a function of time since the last major burst of star formation (tburst). We find evidence for high-velocity outflows in the star-forming progenitor population (vout ∼ 1400 ± 210 km s-1), for recently quenched galaxies with tburst < 0.6 Gyr (vout ∼ 990 ± 250 km s-1), and for older quenched galaxies with 0.6 < tburst < 1 Gyr (vout 1400 ± 220 km s-1). The oldest galaxies (tburst > 1 Gyr) show no evidence for significant outflows. Our samples show no signs of active galactic nucleus (AGN) in optical observations, suggesting that any AGN in these galaxies have very short duty cycles, and were ‘off’ when observed. The presence of significant outflows in the older quenched galaxies (tburst > 0.6 Gyr) is difficult to explain with starburst activity, however, and may indicate energy input from episodic AGN activity as the starburst fades.
Original languageEnglish
Pages (from-to)1684-1692
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume535
Issue number2
Early online date30 Oct 2024
DOIs
Publication statusPublished - Dec 2024

Keywords

  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: ISM

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