%0 Generic %1 marchi2016constraints %A Marchi, F. %A Pentericci, L. %A Guaita, L. %A Ribeiro, B. %A Castellano, M. %A Schaerer, D. %A Hathi, N. P. %A Lemaux, B. C. %A Grazian, A. %A Fevre, O. Le %A Garilli, B. %A Maccagni, D. %A Amorin, R. %A Bardelli, S. %A Cassata, P. %A Fontana, A. %A Koekemoer, A. M. %A Brun, V. Le %A Tasca, L. A. M. %A Thomas, R. %A Vanzella, E. %A Zamorani, G. %A Zucca, E. %D 2016 %K Lyman continuum escape fraction %T New constraints on the average escape fraction of Lyman continuum radiation in z~4 galaxies from the VIMOS Ultra Deep Survey (VUDS) %U http://arxiv.org/abs/1611.05882 %X Determining the average fraction of Lyman continuum (LyC) photons escaping high redshift galaxies is essential to understand how reionization proceeded in the z>6 Universe. We want to measure the LyC signal from a sample of sources in the CDFS and COSMOS fields for which ultra-deep VIMOS spectroscopy as well as multi-wavelength HST imaging are available. We select a sample of 46 galaxies at $z4$ from the VIMOS Ultra Deep Survey (VUDS) database, such that the VUDS spectra contain the LyC part of the spectra i.e. the rest-frame range $880-910\AA$; taking advantage of the HST imaging we apply a careful cleaning procedure and reject all the sources showing nearby clumps with different colours, that could potentially be lower redshift interlopers. After this procedure the sample is reduced to 33 galaxies. We measure the ratio between ionizing flux (LyC at $895\AA$) and non ionizing emission (at $1500 \AA$) for all individual sources. We also produce a normalized stacked spectrum of all sources. Assuming an intrinsic average $L_\nu(1470)/L_\nu(895)$ of 3, we estimate the individual and average relative escape fraction. We do not detect ionizing radiation from any individual source, although we identify a possible LyC emitter with very high Ly$\alpha$ equivalent width. From the stacked spectrum and assuming a mean transmissivity for the sample, we measure a relative e scape fraction $f_esc^rel=0.06\pm0.03$. We also look for correlations between the limits in the LyC flux and source properties and find a tentative correlation between LyC flux and the EW of the Ly$\alpha$ emission line. Our result implies that the LyC flux emitted by $V=25-26$ star forming galaxies at z$\sim$4 is, at most, very modest, in agreement with previous upper limits from studies based on broad and narrow band imaging.

@misc{marchi2016constraints, abstract = {Determining the average fraction of Lyman continuum (LyC) photons escaping high redshift galaxies is essential to understand how reionization proceeded in the z>6 Universe. We want to measure the LyC signal from a sample of sources in the CDFS and COSMOS fields for which ultra-deep VIMOS spectroscopy as well as multi-wavelength HST imaging are available. We select a sample of 46 galaxies at $z\sim 4$ from the VIMOS Ultra Deep Survey (VUDS) database, such that the VUDS spectra contain the LyC part of the spectra i.e. the rest-frame range $880-910\AA$; taking advantage of the HST imaging we apply a careful cleaning procedure and reject all the sources showing nearby clumps with different colours, that could potentially be lower redshift interlopers. After this procedure the sample is reduced to 33 galaxies. We measure the ratio between ionizing flux (LyC at $895\AA$) and non ionizing emission (at $\sim 1500 \AA$) for all individual sources. We also produce a normalized stacked spectrum of all sources. Assuming an intrinsic average $L_{\nu}(1470)/L_{\nu}(895)$ of 3, we estimate the individual and average relative escape fraction. We do not detect ionizing radiation from any individual source, although we identify a possible LyC emitter with very high Ly$\alpha$ equivalent width. From the stacked spectrum and assuming a mean transmissivity for the sample, we measure a relative e scape fraction $f_{esc}^{rel}=0.06\pm0.03$. We also look for correlations between the limits in the LyC flux and source properties and find a tentative correlation between LyC flux and the EW of the Ly$\alpha$ emission line. Our result implies that the LyC flux emitted by $V=25-26$ star forming galaxies at z$\sim$4 is, at most, very modest, in agreement with previous upper limits from studies based on broad and narrow band imaging.}, added-at = {2016-11-21T09:45:12.000+0100}, author = {Marchi, F. and Pentericci, L. and Guaita, L. and Ribeiro, B. and Castellano, M. and Schaerer, D. and Hathi, N. P. and Lemaux, B. C. and Grazian, A. and Fevre, O. Le and Garilli, B. and Maccagni, D. and Amorin, R. and Bardelli, S. and Cassata, P. and Fontana, A. and Koekemoer, A. M. and Brun, V. Le and Tasca, L. A. M. and Thomas, R. and Vanzella, E. and Zamorani, G. and Zucca, E.}, biburl = {https://www.bibsonomy.org/bibtex/2cee50a0d4f6a65faca9ec26e45aa8db4/miki}, description = {[1611.05882] New constraints on the average escape fraction of Lyman continuum radiation in z~4 galaxies from the VIMOS Ultra Deep Survey (VUDS)}, interhash = {65f1238130ef916bc4f3ca162c6fb852}, intrahash = {cee50a0d4f6a65faca9ec26e45aa8db4}, keywords = {Lyman continuum escape fraction}, note = {cite arxiv:1611.05882Comment: submitted to A&A}, timestamp = {2016-11-21T09:45:12.000+0100}, title = {New constraints on the average escape fraction of Lyman continuum radiation in z~4 galaxies from the VIMOS Ultra Deep Survey (VUDS)}, url = {http://arxiv.org/abs/1611.05882}, year = 2016 }