SHARDS Frontier Fields: Physical Properties of a Low-mass Lyα Emitter at z = 5.75

Hernán-Caballero, A.; Pérez-González, Pablo G.; Diego, Jose M.; Lagattuta, David; Richard, Johan; Schaerer, Daniel; Alonso-Herrero, Almudena; Marino, Raffaella Anna; Sklias, Panos; Alcalde Pampliega, Belén; Cava, Antonio; Conselice, Christopher J.; Dannerbauer, H.; Domínguez-Sánchez, Helena; Eliche-Moral, C.; Esquej, Pilar; Huertas-Company, Marc; Marques-Chaves, R.; Pérez-Fournon, I.; Rawle, Tim; Rodríguez Espinosa, J. M.; Rosa González, Daniel; Rujopakarn, Wiphu
Bibliographical reference

The Astrophysical Journal, Volume 849, Issue 2, article id. 82, 13 pp. (2017).

Advertised on:
11
2017
Number of authors
23
IAC number of authors
5
Citations
13
Refereed citations
12
Description
We analyze the properties of a multiply imaged Lyα (Lyα) emitter at z = 5.75 identified through SHARDS Frontier Fields intermediate-band imaging of the Hubble Frontier Fields (HFF) cluster Abell 370. The source, A370-L57, has low intrinsic luminosity (M UV ∼ ‑16.5), steep UV spectral index (β = ‑2.4 ± 0.1), and extreme rest-frame equivalent width of Lyα ({{EW}}0({Ly}α )={420}-120+180 Å). Two different gravitational lens models predict high magnification (μ ∼ 10–16) for the two detected counterimages, separated by 7″, while a predicted third counterimage (μ ∼ 3–4) is undetected. We find differences of ∼50% in magnification between the two lens models, quantifying our current systematic uncertainties. Integral field spectroscopy of A370-L57 with MUSE shows a narrow (FWHM = 204 ± 10 km s‑1) and asymmetric Lyα profile with an integrated luminosity L(Lyα) ∼ 1042 erg s‑1. The morphology in the Hubble Space Telescope bands comprises a compact clump (r e < 100 pc) that dominates the Lyα and continuum emission and several fainter clumps at projected distances ≲1 kpc that coincide with an extension of the Lyα emission in the SHARDS F823W17 and MUSE observations. The latter could be part of the same galaxy or an interacting companion. We find no evidence of a contribution from active galactic nuclei to the Lyα emission. Fitting of the spectral energy distribution with stellar population models favors a very young (t < 10 Myr), low-mass ({M}* ∼ {10}6.5 {M}ȯ ), and metal-poor (Z ≲ 4 × 10‑3) stellar population. Its modest star formation rate (SFR ∼ 1.0 {M}ȯ yr‑1) implies high specific SFR (sSFR ∼ 2.5 × 10‑7 yr‑1) and SFR density ({{{Σ }}}{SFR}∼ 7{--}35 {M}ȯ yr‑1 kpc‑2). The properties of A370-L57 make it a good representative of the population of galaxies responsible for cosmic reionization.
Related projects
Project Image
Formation and Evolution of Galaxies: Observations in Infrared and other Wavelengths
This IAC research group carries out several extragalactic projects in different spectral ranges, using space as well as ground-based telescopes, to study the cosmological evolution of galaxies and the origin of nuclear activity in active galaxies. The group is a member of the international consortium which built the SPIRE instrument for the
Ismael
Pérez Fournon
Project Image
Starbursts in Galaxies GEFE
Starsbursts play a key role in the cosmic evolution of galaxies, and thus in the star formation (SF) history of the universe, the production of metals, and the feedback coupling galaxies with the cosmic web. Extreme SF conditions prevail early on during the formation of the first stars and galaxies, therefore, the starburst phenomenon constitutes a
Casiana
Muñoz Tuñón
Galaxy proto-cluster
Molecular Gas and Dust in Galaxies Across Cosmic Time
Two of the most fundamental questions in astrophysics are the conversion of molecular gas into stars and how this physical process is a function of environments on all scales, ranging from planetary systems, stellar clusters, galaxies to galaxy clusters. The main goal of this internal project is to get insight into the formation and evolution of
Helmut
Dannerbauer