Abstract
We investigate the prevalence of galactic-scale outflows in post-starburst (PSB) galaxies at high redshift (1 < z
< 1.4), using the deep optical spectra available in the UKIDSS Ultra
Deep Survey (UDS). We use a sample of ∼40 spectroscopically confirmed
PSBs, recently identified in the UDS field, and perform a stacking
analysis in order to analyse the structure of strong interstellar
absorption features such as Mg ii (λ2800 Å). We find that for massive (M∗>1010M⊙) PSBs at z > 1, there is clear evidence for a strong blue-shifted component to the Mg ii absorption feature, indicative of high-velocity outflows (vout∼1150±160kms−1)
in the interstellar medium. We conclude that such outflows are typical
in massive PSBs at this epoch, and potentially represent the residual
signature of a feedback process that quenched these galaxies. Using full
spectral fitting, we also obtain a typical stellar velocity
dispersion σ* for these PSBs of ∼200kms−1, which confirms they are intrinsically massive in nature (dynamical mass Md∼1011M⊙). Given that these high-z PSBs are also exceptionally compact (re ∼ 1–2kpc) and spheroidal (Sérsic index n
∼ 3), we propose that the outflowing winds may have been launched
during a recent compaction event (e.g. major merger or disc collapse)
that triggered either a centralized starburst or active galactic nuclei
(AGN) activity. Finally, we find no evidence for AGN signatures in the
optical spectra of these PSBs, suggesting they were either quenched by
stellar feedback from the starburst itself, or that if AGN feedback is
responsible, the AGN episode that triggered quenching does not linger
into the post-starburst phase.
Original language | English |
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Pages (from-to) | 1139-1151 |
Number of pages | 13 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 489 |
Issue number | 1 |
Early online date | 12 Aug 2019 |
DOIs | |
Publication status | Published - 1 Oct 2019 |
Keywords
- astro-ph.GA