The UV-brightest Lyman continuum emitting star-forming galaxy. (arXiv:2107.12313v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Marques_Chaves_R/0/1/0/all/0/1">Rui Marques-Chaves</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schaerer_D/0/1/0/all/0/1">Daniel Schaerer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alvarez_Marquez_J/0/1/0/all/0/1">Javier Alvarez-Marquez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Colina_L/0/1/0/all/0/1">Lui Colina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dessauges_Zavadsky_M/0/1/0/all/0/1">Miroslava Dessauges-Zavadsky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Perez_Fournon_I/0/1/0/all/0/1">Ismael Perez-Fournon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saldana_Lopez_A/0/1/0/all/0/1">Alberto Saldana-Lopez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Verhamme_A/0/1/0/all/0/1">Anne Verhamme</a>
We report the discovery of J0121+0025, an extremely luminous and young
star-forming galaxy (M_UV = -24.11, log[L_Lya / erg s^-1] = 43.8) at z = 3.244
showing copious Lyman continuum (LyC) leakage (f_esc,abs ~ 40%). High SNR
rest-frame UV spectroscopy with the Gran Telescopio Canarias reveals a high
significance (7.9 sigma) emission below the Lyman limit (< 912A), with a flux
density level f_900A = 0.78 +/- 0.10 uJy, and strong P-Cygni in wind lines of
OVI 1033A, NV 1240A and CIV 1550A 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 ISM absorption lines are also detected, but are weak (EW0 ~ 1A)
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 4.5um imaging show that the spectral energy distribution of
J0121+0025 is dominated by the emission of the young starburst, with
log(M*/Msun) = 9.9 +/- 0.1 and SFR = 981 +/- 232 Msun 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.
We report the discovery of J0121+0025, an extremely luminous and young
star-forming galaxy (M_UV = -24.11, log[L_Lya / erg s^-1] = 43.8) at z = 3.244
showing copious Lyman continuum (LyC) leakage (f_esc,abs ~ 40%). High SNR
rest-frame UV spectroscopy with the Gran Telescopio Canarias reveals a high
significance (7.9 sigma) emission below the Lyman limit (< 912A), with a flux
density level f_900A = 0.78 +/- 0.10 uJy, and strong P-Cygni in wind lines of
OVI 1033A, NV 1240A and CIV 1550A 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 ISM absorption lines are also detected, but are weak (EW0 ~ 1A)
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 4.5um imaging show that the spectral energy distribution of
J0121+0025 is dominated by the emission of the young starburst, with
log(M*/Msun) = 9.9 +/- 0.1 and SFR = 981 +/- 232 Msun 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.
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