2018MNRAS.474.4514I -
Mon. Not. R. Astron. Soc., 474, 4514-4527 (2018/March-2)
J1154+2443: a low-redshift compact star-forming galaxy with a 46 per cent leakage of Lyman continuum photons.
IZOTOV Y.I., SCHAERER D., WORSECK G., GUSEVA N.G., THUAN T.X., VERHAMME A., ORLITOVA I. and FRICKE K.J.
Abstract (from CDS):
We report the detection of the Lyman continuum (LyC) radiation of the compact star-forming galaxy (SFG) J1154+2443 observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope. This galaxy, at a redshift of z = 0.3690, is characterized by a high emission-line flux ratio O32 = [O III] λ5007/[O II] λ3727 = 11.5. The escape fraction of the LyC radiation fesc(LyC) in this galaxy is 46 per cent, the highest value found so far in low-redshift SFGs and one of the highest values found in galaxies at any redshift. The narrow double-peaked Ly α emission line is detected in the spectrum of J1154+2443 with a separation between the peaks Vsep of 199 km s–1, one of the lowest known for Ly α-emitting galaxies, implying a high fesc(Ly α). Comparing the extinction-corrected Ly α/H β flux ratio with the case B value, we find fesc(Ly α) = 98 per cent. Our observations, combined with previous detections in the literature, reveal an increase of O32 with increasing fesc(LyC). We also find a tight anticorrelation between fesc(LyC) and Vsep. The surface brightness profile derived from the COS acquisition image reveals a bright star-forming region in the centre and an exponential disc in the outskirts with a disc scale length α = 1.09 kpc. J1154+2443, compared to other known low-redshift LyC leakers, is characterized by the lowest metallicity, 12+log O/H = 7.65 ± 0.01, the lowest stellar mass M* = 108.20 M☉, a similar star formation rate SFR = 18.9 M☉ yr–1, and a high specific SFR of 1.2 x 10–7 yr–1.
Abstract Copyright:
© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
galaxies: abundances - galaxies: dwarf - galaxies: fundamental parameters - galaxies: ISM - galaxies: starburst - dark ages, reionization, first stars
Simbad objects:
7
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