Properties of five z ∼ 0.3-0.4 confirmed LyC leakers: VLT/XShooter observations
Using new Very Large Telescope (VLT)/XShooter spectral observations we analyse the physical properties of five z similar to 0.3-0.4 confirmed Lyman continuum (LyC) leakers. Strong resonant MgII lambda lambda 2796, 2803 angstrom emission lines (I(lambda lambda 2796, 2803)/I(H beta) similar or equal t...
| Autores: | , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/224402 |
| Acceso en línea: | http://hdl.handle.net/10261/224402 |
| Access Level: | acceso abierto |
| Palabra clave: | Galaxies: abundances Galaxies: dwarf Galaxies: ISM Galaxies: starburst |
| Sumario: | Using new Very Large Telescope (VLT)/XShooter spectral observations we analyse the physical properties of five z similar to 0.3-0.4 confirmed Lyman continuum (LyC) leakers. Strong resonant MgII lambda lambda 2796, 2803 angstrom emission lines (I(lambda lambda 2796, 2803)/I(H beta) similar or equal to 10-38 per cent) and non-resonant Fe II* lambda lambda 2612, 2626 angstrom emission lines are observed in spectra of five and three galaxies, respectively. We find high electron densities N-e similar to 400 cm(-3), significantly higher than in typical low-z, but comparable to those measured in z similar to 2-3 star-forming galaxies (SFGs). The galaxies have a mean value of log N/O = -1.16, close to the maximum values found for SFGs in the metallicity range of 12 + logO/H similar or equal to 7.7-8.1. All 11 low-z LyC emitting galaxies found by Izotov et al., including the ones considered in this study, are characterized by high equivalent width (EW) (H beta) similar to 200-400 angstrom, high ionization parameter (log(U) = -2.5 to -1.7), high average ionizing photon production efficiency xi = 10(25.54) Hz erg(-1), and hard ionizing radiation. On the Baldwin-Phillips-Terlevich (BPT) diagram we find the same offset of our leakers from low-z main-sequence SFGs as that for local analogues of Lyman-break galaxies (LBGs) and extreme SFGs at z similar to 2-3. We confirm the effectiveness of the He I emission lines diagnostics proposed by Izotov et al. in searching for LyC leaker candidates and find that their intensity ratios correspond to those in a median with low neutral hydrogen column density N(H I) = 10(17)-5 x 10(17) cm(-2) that permit leakage of LyC radiation, likely due to their density-bounded HII regions. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society |
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