High Redshift LAEs and their Cosmic Evolution: Morphologies, SFR and AGN Activity from z~2 to 6

Barlow-Hall, Cassandra and Bramwell, Joseph and Hodder, Daniel and Merrett, Michael and Russ, Adam and Wareing, Oliver and Sobral, David (2019) High Redshift LAEs and their Cosmic Evolution: Morphologies, SFR and AGN Activity from z~2 to 6. Notices of Lancaster Astrophysics (NLUAstro), 1. pp. 39-58.

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Abstract

We studied a large sample of ∼ 4000 high redshift Lyman-alpha Emitters (LAEs) in order to determine their properties and infer how they might have evolved into the local Universe. This was done through the exploration of the SC4K survey (Sobral et al. 2018a) and making use of the Hubble Space Telescope (HST), Chandra X-ray Observatory (Chandra) and the Very Large Array (VLA). We find that SC4K LAEs are mostly (69 ± 4%) compact disky galaxies (average S ́ersic index, n = 1.9 ± 2.2) The average star formation rate SFRLyα of LAEs is ≈ 17 M⊙ yr−1 . We find that SFR increases with increasing stellar mass. We also observed a characteristic ‘peak’ in SFR at M ∼ 10^9.3 M⊙, at redshift z ∼ 2.5, and progressing to higher stellar masses at higher redshifts. We find a total of 303 X-ray or radio detected active galactic nuclei (AGN) within the SC4K catalogue. These AGN have a range of black hole accretion rates (BHARs) from ∼ 0.03 M⊙ yr−1 to ∼ 3.3 M⊙ yr−1. The AGN fraction increases with increasing Lyα luminosity and decreases with increasing redshift, peaking at z ∼ 3. LAEs found at z ∼ 2−6 with a stellar mass M ∼ 10^10 M⊙ and a SFR ∼ 5.4M⊙yr−1 are consistent with being progenitors of Milky Way-like galaxies progenitor. Additionally, we found that the majority of the SC4K LAEs consists of cluster-like progenitors that will go on to form the brightest cluster galaxies (BCGs) in the local Universe.