Aim: We aim to measure the LyC signal from a sample of sources in the Chandra
deep field south. We collect star-forming galaxies (SFGs) and active galactic
nuclei (AGN) with accurate spectroscopic redshifts, for which Hubble Space
Telescope (HST) coverage and multi-wavelength photometry are available. Method:
We selected a sample of about 200 sources at z~3. Taking advantage of HST
resolution, we applied a careful cleaning procedure and rejected sources
showing nearby clumps with different colours, which could be lower-z
interlopers. Our clean sample consisted of 86 SFGs (including 19 narrow-band
selected Lya emitters) and 8 AGN (including 6 detected in X-rays). We measured
the LyC flux from aperture photometry in four narrow-band filters covering
wavelengths below a 912 A rest frame (3.11<z<3.53). We estimated the ratio
between ionizing (LyC flux) and 1400 A non-ionizing emissions for AGN and
galaxies. Results: By running population synthesis models, we assume an average
intrinsic L(1400 A)/L(900 A) ratio of 5 as the representative value for our
sample. With this value and an average treatment of the lines of sight of the
inter-galactic medium, we estimate the LyC escape fraction relative to the
intrinsic value (fesc_rel(LyC)). We do not directly detect ionizing radiation
from any individual SFG, but we are able to set a 1(2)sigma upper limit of
fesc_rel(LyC)<12(24)%. This result is consistent with other non-detections
published in the literature. No meaningful limits can be calculated for the
sub-sample of Lya emitters. We obtain one significant direct detection for an
AGN at z=3.46, with fesc_rel(LyC) = (72+/-18)%. Conclusions: Our upper limit on
fescrel(LyC) implies that the SFGs studied here do not present either the
physical properties or the geometric conditions suitable for efficient
LyC-photon escape.
Beschreibung
[1601.03057] Limits on the LyC signal from z~3 sources with secure redshift and HST coverage in the E-CDFS field
%0 Generic
%1 guaita2016limits
%A Guaita, L.
%A Pentericci, L.
%A Grazian, A.
%A Vanzella, E.
%A Nonino, M.
%A Giavalisco, M.
%A Zamorani, G.
%A Bongiorno, A.
%A Cassata, P.
%A Castellano, M.
%A Garilli, B.
%A Gawiser, E.
%A Brun, V. Le
%A Fevre, O. Le
%A Lemaux, B. C.
%A Maccagni, D.
%A Merlin, E.
%A Santini, P.
%A Tasca, L. A. M.
%A Thomas, R.
%A Zucca, E.
%A De Barros, S.
%A Hathi, N. P.
%A Amorin, R.
%A Bardelli, S.
%A Fontana, A.
%D 2016
%K emission galaxy high-z ionisation lyc
%T Limits on the LyC signal from z~3 sources with secure redshift and HST
coverage in the E-CDFS field
%U http://arxiv.org/abs/1601.03057
%X Aim: We aim to measure the LyC signal from a sample of sources in the Chandra
deep field south. We collect star-forming galaxies (SFGs) and active galactic
nuclei (AGN) with accurate spectroscopic redshifts, for which Hubble Space
Telescope (HST) coverage and multi-wavelength photometry are available. Method:
We selected a sample of about 200 sources at z~3. Taking advantage of HST
resolution, we applied a careful cleaning procedure and rejected sources
showing nearby clumps with different colours, which could be lower-z
interlopers. Our clean sample consisted of 86 SFGs (including 19 narrow-band
selected Lya emitters) and 8 AGN (including 6 detected in X-rays). We measured
the LyC flux from aperture photometry in four narrow-band filters covering
wavelengths below a 912 A rest frame (3.11<z<3.53). We estimated the ratio
between ionizing (LyC flux) and 1400 A non-ionizing emissions for AGN and
galaxies. Results: By running population synthesis models, we assume an average
intrinsic L(1400 A)/L(900 A) ratio of 5 as the representative value for our
sample. With this value and an average treatment of the lines of sight of the
inter-galactic medium, we estimate the LyC escape fraction relative to the
intrinsic value (fesc_rel(LyC)). We do not directly detect ionizing radiation
from any individual SFG, but we are able to set a 1(2)sigma upper limit of
fesc_rel(LyC)<12(24)%. This result is consistent with other non-detections
published in the literature. No meaningful limits can be calculated for the
sub-sample of Lya emitters. We obtain one significant direct detection for an
AGN at z=3.46, with fesc_rel(LyC) = (72+/-18)%. Conclusions: Our upper limit on
fescrel(LyC) implies that the SFGs studied here do not present either the
physical properties or the geometric conditions suitable for efficient
LyC-photon escape.
@misc{guaita2016limits,
abstract = {Aim: We aim to measure the LyC signal from a sample of sources in the Chandra
deep field south. We collect star-forming galaxies (SFGs) and active galactic
nuclei (AGN) with accurate spectroscopic redshifts, for which Hubble Space
Telescope (HST) coverage and multi-wavelength photometry are available. Method:
We selected a sample of about 200 sources at z~3. Taking advantage of HST
resolution, we applied a careful cleaning procedure and rejected sources
showing nearby clumps with different colours, which could be lower-z
interlopers. Our clean sample consisted of 86 SFGs (including 19 narrow-band
selected Lya emitters) and 8 AGN (including 6 detected in X-rays). We measured
the LyC flux from aperture photometry in four narrow-band filters covering
wavelengths below a 912 A rest frame (3.11<z<3.53). We estimated the ratio
between ionizing (LyC flux) and 1400 A non-ionizing emissions for AGN and
galaxies. Results: By running population synthesis models, we assume an average
intrinsic L(1400 A)/L(900 A) ratio of 5 as the representative value for our
sample. With this value and an average treatment of the lines of sight of the
inter-galactic medium, we estimate the LyC escape fraction relative to the
intrinsic value (fesc_rel(LyC)). We do not directly detect ionizing radiation
from any individual SFG, but we are able to set a 1(2)sigma upper limit of
fesc_rel(LyC)<12(24)%. This result is consistent with other non-detections
published in the literature. No meaningful limits can be calculated for the
sub-sample of Lya emitters. We obtain one significant direct detection for an
AGN at z=3.46, with fesc_rel(LyC) = (72+/-18)%. Conclusions: Our upper limit on
fescrel(LyC) implies that the SFGs studied here do not present either the
physical properties or the geometric conditions suitable for efficient
LyC-photon escape.},
added-at = {2016-01-14T10:25:34.000+0100},
author = {Guaita, L. and Pentericci, L. and Grazian, A. and Vanzella, E. and Nonino, M. and Giavalisco, M. and Zamorani, G. and Bongiorno, A. and Cassata, P. and Castellano, M. and Garilli, B. and Gawiser, E. and Brun, V. Le and Fevre, O. Le and Lemaux, B. C. and Maccagni, D. and Merlin, E. and Santini, P. and Tasca, L. A. M. and Thomas, R. and Zucca, E. and De Barros, S. and Hathi, N. P. and Amorin, R. and Bardelli, S. and Fontana, A.},
biburl = {https://www.bibsonomy.org/bibtex/27f47ff3959717d145897b4d4e07b3657/miki},
description = {[1601.03057] Limits on the LyC signal from z~3 sources with secure redshift and HST coverage in the E-CDFS field},
interhash = {f1108cb12b83d44585e75788f426dac4},
intrahash = {7f47ff3959717d145897b4d4e07b3657},
keywords = {emission galaxy high-z ionisation lyc},
note = {cite arxiv:1601.03057Comment: Accepted for publication in A&A on Jan 5th, 2016},
timestamp = {2016-01-14T10:26:25.000+0100},
title = {Limits on the LyC signal from z~3 sources with secure redshift and HST
coverage in the E-CDFS field},
url = {http://arxiv.org/abs/1601.03057},
year = 2016
}