SHARDS frontier fields: physical properties of a low-mass Lyα emitter at z = 5.75

Hern�n-Caballero, Antonio; P�rez-Gonz�lez, Pablo G.; Diego, Jose M.; Lagattuta, David; Richard, Johan; Schaerer, Daniel; Alonso-Herrero, Almudena; Marino, Raffaella Anna; Sklias, Panos; Alcalde Pampliega, Bel�n; Cava, Antonio; Conselice, Christopher J.; Dannerbauer, Helmut; Dom�nguez-S�nchez, Helena; Eliche-Moral, Carmen; Esquej, Pilar; Huertas-Company, Marc; Marques-Chaves, Rui; Perez-Fournon, Ismael; Rawle, Tim; Espinosa, Jos� Miguel Rodr�guez; Gonz�lez, Daniel Rosa; Rujopakarn, Wiphu

Abstract

© 2017. The American Astronomical Society. All rights reserved. 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. 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) ∼ 10 42 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 (), and metal-poor (Z ≲ 4 10 -3 ) stellar population. Its modest star formation rate (SFR ∼ 1.0 yr -1 ) implies high specific SFR (sSFR ∼ 2.5 10 -7 yr -1 ) and SFR density ( yr -1 kpc -2 ). The properties of A370-L57 make it a good representative of the population of galaxies responsible for cosmic reionization.

Citation

Hernán-Caballero, A., Pérez-González, P. G., Diego, J. M., Lagattuta, D., Richard, J., Schaerer, D., Alonso-Herrero, A., Marino, R. A., Sklias, P., Alcalde Pampliega, B., Cava, A., Conselice, C. J., Dannerbauer, H., Domínguez-Sánchez, H., Eliche-Moral, C., Esquej, P., Huertas-Company, M., Marques-Chaves, R., Perez-Fournon, I., Rawle, T., …Rujopakarn, W. (2017). SHARDS frontier fields: physical properties of a low-mass Lyα emitter at z = 5.75. Astrophysical Journal, 849(2), Article 82. https://doi.org/10.3847/1538-4357/aa917f

• Journal Article Type: Article
• Acceptance Date: Oct 2, 2017
• Publication Date: Nov 6, 2017
• Deposit Date: Dec 11, 2017
• Publicly Available Date: Dec 11, 2017
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 849
• Issue: 2
• Article Number: 82
• DOI: https://doi.org/10.3847/1538-4357/aa917f
• Keywords: Dark ages; Teionization; First stars; Early universe; Galaxies: evolution; Galaxies: high red-shift; Galaxies: starburst; Gravitational lensing; Strong
• Public URL: https://nottingham-repository.worktribe.com/output/892941
• Publisher URL: https://doi.org/10.3847/1538-4357/aa917f
• Additional Information: © Copyright 2017 IOP Publishing
• Contract Date: Dec 11, 2017