Proyecto de Investigación: ENTORNOS GALACTICOS Y EVOLUCION: INVESTIGACION TEORICA CON ASTROFISICA COMPUTACIONAL
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PGC2018-094975-B-C22
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The discovery of the most UV–Ly α luminous star-forming galaxy: a young, dust- and metal-poor starburst with QSO-like luminosities
(Oxford Academics: Oxford University Press, 2020-09-16) Marques Chaves, R.; Álvarez Márquez, J.; Colina, L.; Pérez Fournon, I.; Schaerer, D.; Dalla Vecchia, C.; Hashimoto, T.; Jiménez Ángel, C.; Shu, Y.; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Shu, Y. [0000-0002-9063-698X]; Dalla Vecchia, C. [0000-0002-2620-7056]; Marqués Chaves, R. [0000-0001-8442-1846]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We report the discovery of BOSS-EUVLG1 at z = 2.469, by far the most luminous, almost un-obscured star-forming galaxy known at any redshift. First classified as a QSO within the Baryon Oscillation Spectroscopic Survey, follow-up observations with the Gran Telescopio Canarias reveal that its large luminosity, M-UV similar or equal to -24.40 and log(L-Ly alpha/erg s(-1)) similar or equal to 44.0, is due to an intense burst of star formation, and not to an active galactic nucleus or gravitational lensing. BOSS-EUVLG1 is a compact (r(eff) similar or equal to 1.2 kpc), young (4-5 Myr) starburst with a stellar mass log(M-*/M-circle dot) = 10.0 +/- 0.1 and a prodigious star formation rate of similar or equal to 1000 M-circle dot yr(-1). However, it is metal- and dust-poor [12+ log(O/H) = 8.13 +/- 0.19, E(B - V) similar or equal to 0.07, log(L-IR/L-UV) < -1.2], indicating that we are witnessing the very early phase of an intense starburst that has had no time to enrich the ISM. BOSS-EUVLG1 might represent a short-lived (<100 Myr), yet important phase of star-forming galaxies at high redshift that has been missed in previous surveys. Within a galaxy evolutionary scheme, BOSS-EUVLG1 could likely represent the very initial phases in the evolution of massive quiescent galaxies, even before the dusty star-forming phase.
The UV-brightest Lyman continuum emitting star-forming galaxy
(Oxford Academics: Oxford University Press, 2021-07-30) Marques Chaves, R.; Schaerer, D.; Álvarez Márquez, J.; Colina, L.; Dessauges-Zavadsky, M.; Pérez Fournon, I.; Saldana López, A.; Verhamme, A.; Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We report the discovery of J0121+0025, an extremely luminous and young star-forming galaxy (MUV = −24.11, log[LLyα/erg s−1]=43.8) at z = 3.244 showing copious Lyman continuum (LyC) leakage (fesc,abs≈40 per cent). High signal-to-noise ratio rest-frame UV spectroscopy with the Gran Telescopio Canarias reveals a high significance (7.9σ) emission below the Lyman limit (<912 Å), with a flux density level f900 = 0.78 ± 0.10μJy, and strong P-Cygni in wind lines of O VI 1033 Å, N V 1240 Å, and C IV 1550 Å that are indicative of a young age of the starburst (<10 Myr). The spectrum is rich in stellar photospheric features, for which a significant contribution of an AGN at these wavelengths is ruled out. Low-ionization interstellar medium (ISM) absorption lines are also detected, but are weak (EW0≃1 Å) and show large residual intensities, suggesting a clumpy geometry of the gas with a non-unity covering fraction or a highly ionized ISM. The contribution of a foreground and AGN contamination to the LyC signal is unlikely. Deep optical to Spitzer/IRAC 4.5 μm imaging show that the spectral energy distribution of J0121+0025 is dominated by the emission of the young starburst, with log(Mburst⋆/M⊙)=9.9±0.1 and SFR=981±232 M⊙ yr−1. J0121+0025 is the most powerful LyC emitter known among the star-forming galaxy population. The discovery of such luminous and young starburst leaking LyC radiation suggests that a significant fraction of LyC photons can escape in sources with a wide range of UV luminosities and are not restricted to the faintest ones as previously thought. These findings might shed further light on the role of luminous starbursts to the cosmic reionization.
