Re-examining the case for neutral gas near the redshift 7 quasar ULAS
J1120+0641
S. Bosman, and G. Becker. (2015)cite arxiv:1505.06880Comment: 8 pages, 6 figures MNRAS submitted.
Abstract
Signs of damping wing absorption attenuating the Lyman-$\alpha$ emission line
of the first known $z 7$ quasar, ULAS J1120+0641, recently provided
exciting evidence of a significantly neutral IGM. This long-awaited signature
of reionization was inferred, in part, from a deficit of flux in the quasar's
Lyman-$\alpha$ emission line based on predictions from a composite of
lower-redshift quasars. The composite sample was chosen based on its C IV
emission line properties; however, as the original study by Mortlock et al.
noted, the composite contained a slight velocity offset in C IV compared to
ULAS J1120+0641. Here we test whether this offset may be related to the
predicted strength of the Lyman-$\alpha$ emission line. We confirm the
significant ($10$ per cent at r.m.s.) scatter in Lyman-$\alpha$ flux for
quasars of a given C IV velocity and equivalent width found by Mortlock et al.
We further find that among lower-redshift objects chosen to more closely match
the C IV properties of ULAS J1120+0641, its Lyman-$\alpha$ emission falls
within the observed distribution of fluxes. Among lower-redshift quasars chosen
to more closely match in C IV velocity and equivalent width, we find that ULAS
J1120+0641 falls within the observed distribution of Lyman-$\alpha$ emission
line strengths. This suggests that damping wing absorption may not be present,
potentially weakening the case for neutral gas around this object. Larger
samples of z$>$7 quasars may therefore be needed to establish a clearer picture
of the IGM neutral fraction at these redshifts.
Description
[1505.06880] Re-examining the case for neutral gas near the redshift 7 quasar ULAS J1120+0641
%0 Generic
%1 bosman2015reexamining
%A Bosman, Sarah E. I.
%A Becker, George D.
%D 2015
%K igm quasars reionization
%T Re-examining the case for neutral gas near the redshift 7 quasar ULAS
J1120+0641
%U http://arxiv.org/abs/1505.06880
%X Signs of damping wing absorption attenuating the Lyman-$\alpha$ emission line
of the first known $z 7$ quasar, ULAS J1120+0641, recently provided
exciting evidence of a significantly neutral IGM. This long-awaited signature
of reionization was inferred, in part, from a deficit of flux in the quasar's
Lyman-$\alpha$ emission line based on predictions from a composite of
lower-redshift quasars. The composite sample was chosen based on its C IV
emission line properties; however, as the original study by Mortlock et al.
noted, the composite contained a slight velocity offset in C IV compared to
ULAS J1120+0641. Here we test whether this offset may be related to the
predicted strength of the Lyman-$\alpha$ emission line. We confirm the
significant ($10$ per cent at r.m.s.) scatter in Lyman-$\alpha$ flux for
quasars of a given C IV velocity and equivalent width found by Mortlock et al.
We further find that among lower-redshift objects chosen to more closely match
the C IV properties of ULAS J1120+0641, its Lyman-$\alpha$ emission falls
within the observed distribution of fluxes. Among lower-redshift quasars chosen
to more closely match in C IV velocity and equivalent width, we find that ULAS
J1120+0641 falls within the observed distribution of Lyman-$\alpha$ emission
line strengths. This suggests that damping wing absorption may not be present,
potentially weakening the case for neutral gas around this object. Larger
samples of z$>$7 quasars may therefore be needed to establish a clearer picture
of the IGM neutral fraction at these redshifts.
@misc{bosman2015reexamining,
abstract = {Signs of damping wing absorption attenuating the Lyman-$\alpha$ emission line
of the first known $z \sim 7$ quasar, ULAS J1120+0641, recently provided
exciting evidence of a significantly neutral IGM. This long-awaited signature
of reionization was inferred, in part, from a deficit of flux in the quasar's
Lyman-$\alpha$ emission line based on predictions from a composite of
lower-redshift quasars. The composite sample was chosen based on its C IV
emission line properties; however, as the original study by Mortlock et al.
noted, the composite contained a slight velocity offset in C IV compared to
ULAS J1120+0641. Here we test whether this offset may be related to the
predicted strength of the Lyman-$\alpha$ emission line. We confirm the
significant ($\sim 10$ per cent at r.m.s.) scatter in Lyman-$\alpha$ flux for
quasars of a given C IV velocity and equivalent width found by Mortlock et al.
We further find that among lower-redshift objects chosen to more closely match
the C IV properties of ULAS J1120+0641, its Lyman-$\alpha$ emission falls
within the observed distribution of fluxes. Among lower-redshift quasars chosen
to more closely match in C IV velocity and equivalent width, we find that ULAS
J1120+0641 falls within the observed distribution of Lyman-$\alpha$ emission
line strengths. This suggests that damping wing absorption may not be present,
potentially weakening the case for neutral gas around this object. Larger
samples of z$>$7 quasars may therefore be needed to establish a clearer picture
of the IGM neutral fraction at these redshifts.},
added-at = {2015-05-27T11:10:59.000+0200},
author = {Bosman, Sarah E. I. and Becker, George D.},
biburl = {https://www.bibsonomy.org/bibtex/2b08c0d9cdab61920ad4c7427b3b3e8c1/miki},
description = {[1505.06880] Re-examining the case for neutral gas near the redshift 7 quasar ULAS J1120+0641},
interhash = {24db7648d3cc8ced243f40f07eefbef2},
intrahash = {b08c0d9cdab61920ad4c7427b3b3e8c1},
keywords = {igm quasars reionization},
note = {cite arxiv:1505.06880Comment: 8 pages, 6 figures MNRAS submitted},
timestamp = {2015-05-27T11:10:59.000+0200},
title = {Re-examining the case for neutral gas near the redshift 7 quasar ULAS
J1120+0641},
url = {http://arxiv.org/abs/1505.06880},
year = 2015
}