%0 Generic %1 smith2016hubble %A Smith, Brent M. %A Windhorst, Rogier A. %A Jansen, Rolf A. %A Cohen, Seth H. %A Jiang, Linhua %A Dijkstra, Mark %A Koekemoer, Anton M. %A Bielby, Richard %A Inoue, Akio K. %A MacKenty, John W. %A O'Connell, Robert W. %A Silk, Joseph I. %D 2016 %K agn escape forming fraction high-z star %T Hubble Space Telescope Wide Field Camera 3 Observations of Escaping Lyman Continuum Radiation from Galaxies and Weak AGN at Redshifts z~2.3--5 %U http://arxiv.org/abs/1602.01555 %X We present observations of escaping Lyman Continuum (LyC) radiation from 50 massive star-forming galaxies and 14 weak AGN with reliable spectroscopic redshifts at z~2.3--5.8. We analyzed HST WFC3/UVIS mosaics of the ERS field in three UV filters, and ACS B in the GOODS-South field to sample the rest-frame LyC over these redshifts. The average LyC emission of galaxies at z_mean=2.38, 2.68, 3.47, and 5.02 is detected at the >=3sigma level in image stacks of 11--15 galaxies in the WFC3/UVIS F225W, F275W, F336W, and ACS/WFC F435W filters. Their average LyC flux corresponds to AB~29.5--30.7 mag. The LyC flux of weak AGN is typically ~1 mag brighter at z~2.3--4.8, but averaged over ~4x fewer galaxies. The stacked galaxy LyC profiles are flatter than their non-ionizing UV-continuum profiles out to r~0".7, possibly indicating a radial porosity dependence in the ISM. The average LyC emission from AGN is more extended and sometimes more elongated compared to galaxies without AGN, possibly due to the viewing-angle at which LyC escapes. With SED fits to UV-continuum longwards of Lya and IGM transmission models, we find absolute LyC escape fractions of fesc_abs~0.1--18% at z~2.3--3.9, and marginal constraints at z=5.02. Available data for galaxies, including published work, suggests a sudden increase of f_esc at z~3. Our models imply that dust accumulating in (massive) galaxies may be a major factor in reducing f_esc at z<=3. Our best fits of f_esc(z) suggest that star-forming galaxies collectively contributed to maintaining cosmic reionization at redshifts z>=3--6, while AGN likely dominated reionization at z<=2.5.

@misc{smith2016hubble, abstract = {We present observations of escaping Lyman Continuum (LyC) radiation from 50 massive star-forming galaxies and 14 weak AGN with reliable spectroscopic redshifts at z~2.3--5.8. We analyzed HST WFC3/UVIS mosaics of the ERS field in three UV filters, and ACS B in the GOODS-South field to sample the rest-frame LyC over these redshifts. The average LyC emission of galaxies at z_mean=2.38, 2.68, 3.47, and 5.02 is detected at the >=3sigma level in image stacks of 11--15 galaxies in the WFC3/UVIS F225W, F275W, F336W, and ACS/WFC F435W filters. Their average LyC flux corresponds to AB~29.5--30.7 mag. The LyC flux of weak AGN is typically ~1 mag brighter at z~2.3--4.8, but averaged over ~4x fewer galaxies. The stacked galaxy LyC profiles are flatter than their non-ionizing UV-continuum profiles out to r~0".7, possibly indicating a radial porosity dependence in the ISM. The average LyC emission from AGN is more extended and sometimes more elongated compared to galaxies without AGN, possibly due to the viewing-angle at which LyC escapes. With SED fits to UV-continuum longwards of Lya and IGM transmission models, we find absolute LyC escape fractions of fesc_abs~0.1--18% at z~2.3--3.9, and marginal constraints at z=5.02. Available data for galaxies, including published work, suggests a sudden increase of f_esc at z~3. Our models imply that dust accumulating in (massive) galaxies may be a major factor in reducing f_esc at z<=3. Our best fits of f_esc(z) suggest that star-forming galaxies collectively contributed to maintaining cosmic reionization at redshifts z>=3--6, while AGN likely dominated reionization at z<=2.5.}, added-at = {2016-02-05T10:03:51.000+0100}, author = {Smith, Brent M. and Windhorst, Rogier A. and Jansen, Rolf A. and Cohen, Seth H. and Jiang, Linhua and Dijkstra, Mark and Koekemoer, Anton M. and Bielby, Richard and Inoue, Akio K. and MacKenty, John W. and O'Connell, Robert W. and Silk, Joseph I.}, biburl = {https://www.bibsonomy.org/bibtex/285e0e1591739679bc3c209fcc33ef521/miki}, description = {[1602.01555] Hubble Space Telescope Wide Field Camera 3 Observations of Escaping Lyman Continuum Radiation from Galaxies and Weak AGN at Redshifts z~2.3--5}, interhash = {f792d035ccc3df0cd774fbed3560a2d7}, intrahash = {85e0e1591739679bc3c209fcc33ef521}, keywords = {agn escape forming fraction high-z star}, note = {cite arxiv:1602.01555Comment: 40 pages (4 appendices), 13 (+9) figures, 3 (+4) tables; AASTeX6, pdflatex; submitted to ApJ}, timestamp = {2016-02-05T10:03:51.000+0100}, title = {Hubble Space Telescope Wide Field Camera 3 Observations of Escaping Lyman Continuum Radiation from Galaxies and Weak AGN at Redshifts z~2.3--5}, url = {http://arxiv.org/abs/1602.01555}, year = 2016 }