Post-starburst galaxies: more than just an interesting curiosity

Abstract

From the VIMOS VLT DEEP Survey (VVDS) we select a sample of 16 galaxies with spectra which identify them as having recently undergone a strong starburst and subsequent fast quenching of star formation. These post-starburst galaxies lie in the redshift range 0.5<z<1.0 with masses >10^9.75Msun. They have a number density of 1x10^-4 per Mpc^3, almost two orders of magnitude sparser than the full galaxy population with the same mass limit. We compare with simulations to show that the galaxies are consistent with being the descendants of gas rich major mergers. Starburst mass fractions must be larger than ~5-10% and decay times shorter than ~10^8 years for post-starburst spectral signatures to be observed in the simulations. We find that the presence of black hole feedback does not greatly affect the evolution of the simulated merger remnants through the post-starburst phase. The multiwavelength spectral energy distributions of the post-starburst galaxies show that 5/16 have completely ceased the formation of new stars. These 5 galaxies correspond to a mass flux entering the red-sequence of rhodot(A->Q, PSB) = 0.0038Msun/Mpc^3/yr, assuming the defining spectroscopic features are detectable for 0.35Gyr. If the galaxies subsequently remain on the red sequence, this accounts for 38(+4/-11)% of the growth rate of the red sequence. Finally, we compare our high redshift results with a sample of galaxies with 0.05<z<0.1 observed in the SDSS and UKIDSS surveys. We find a very strong redshift evolution: the mass density of strong post-starburst galaxies is 230 times lower at z~0.07 than at z~0.7.Comment: 18 pages, 12 figures, to match version accepted to MNRAS. Minor reordering of text in places and Sec 2.2 on SPH simulation comparisons expande

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Evolutionary stellar population synthesis with MILES – II. Scaled-solar and α-enhanced models

“…There are other methods that employ as many Lick indices as possible and simultaneously fit them in a χ 2 sense (e.g., Vazdekis et al 1997;Proctor, Forbes & Beasley 2004). An alternative method is the use of Principal Component Analysis (e.g., Covino, Galletti & Pasinetti 1995;Wild et al 2009). …”

Evidence of ongoing AGN-driven feedback in a quiescent post-starburst E+A galaxy

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“…In this scenario, a gas-rich major merger triggers a powerful starburst, which can be observed as an ultra luminous infrared galaxy (ULIRG), with SFRs ranging between 100 and 1000 M /yr. The system then evolves into a post starburst galaxy (e.g., Kaviraj et al 2007;Cales & Brotherton 2015) which, in turn, evolves to a quiescent elliptical galaxy (Yang et al 2004(Yang et al , 2006Wild et al 2009Wild et al , 2016. Yesuf et al (2014), Rowlands et al (2015), and Alatalo et al (2016b) studied the dust and molecular gas content in samples of E+A galaxies and generally found significantly more molecular gas and dust, compared to quiescent galaxies.…”