Bibcode
Alcalde Pampliega, Belén; Pérez-González, Pablo G.; Barro, Guillermo; Domínguez Sánchez, Helena; Eliche-Moral, M. Carmen; Cardiel, Nicolás; Hernán-Caballero, Antonio; Rodriguez-Muñoz, Lucía; Sánchez Blázquez, Patricia; Esquej, Pilar
Bibliographical reference
The Astrophysical Journal, Volume 876, Issue 2, article id. 135, 26 pp. (2019).
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5
2019
Journal
Citations
46
Refereed citations
42
Description
We present a sample of 33 Balmer break galaxies (BBGs) selected as
Hubble Space Telescope/F160W dropouts in the deepest CANDELS/GOODS
fields (H ≳ 27.3 mag) but relatively bright in Spitzer/IRAC ([3.6],
[4.5] < 24.5 mag), implying red colors (median and quartiles: <
H-[3.6]> ={3.1}2.83.4 {mag}). Half of these
BBGs are newly identified sources. Our BBGs are massive (<
{log}(M/{M}ȯ )>
={10.8}10.411.0), high-redshift (< z>
={4.8}4.45.1), dusty (< A(V)>
={2.0}1.52.0 {mag}) galaxies. The spectral energy
distributions (SEDs) of half of our sample indicate that they are
star-forming galaxies with typical specific star formation rates (SFRs)
of 0.5–1.0 Gyr‑1, qualifying them as
main-sequence (MS) galaxies at 3 < z < 6. One-third of these SEDs
indicate the presence of prominent emission lines (Hβ + [O III],
Hα + [N II]) boosting the IRAC fluxes and red colors.
Approximately 20% of the BBGs are very dusty (A(V) ∼ 2.5 mag)
starbursts with strong mid-to-far-infrared detections and extreme SFRs
(SFR > 103 M ⊙ yr‑1) that
place them above the MS. The rest, 30%, are post-starbursts or quiescent
galaxies located >2σ below the MS with mass-weighted ages older
than 700 Myr. Only two of the 33 galaxies are X-ray-detected active
galactic nuclei (AGNs) with optical/near-infrared SEDs dominated by
stellar emission, but the presence of obscured AGNs in the rest of the
sources cannot be discarded. Our sample accounts for 8% of the total
number density of {log}(M/{M}ȯ )> 10 galaxies at z
> 3, but it is a significant contributor (30%) to the general
population of red {log}(M/{M}ȯ )> 11 galaxies at 4
< z < 6. Finally, our results point out that one of every 30
massive {log}(M/{M}ȯ )> 11 galaxies in the local
universe was assembled in the first 1.5 Gyr after the big bang, a
fraction that is not reproduced by state-of-the-art galaxy formation
simulations.