The HeII transverse proximity effect -- enhanced HeII Ly$\alpha$~transmission
in a background sightline caused by the ionizing radiation of a foreground
quasar -- offers a unique opportunity to probe the morphology of quasar-driven
HeII reionization. We conduct a comprehensive spectroscopic survey to find
$z\sim3$ quasars in the foreground of 22 background quasar sightlines with
HST/COS HeII Ly$\alpha$~transmission spectra. With our two-tiered survey
strategy, consisting of a deep pencil-beam survey and a shallow wide-field
survey, we discover 131 new quasars, which we complement with known SDSS/BOSS
quasars in our fields. Using a restricted sample of 66 foreground quasars with
inferred HeII photoionization rates greater than the expected UV background at
these redshifts ($\Gamma_QSO^HeII > 5 \times
10^-16\,s^-1$) we perform the first statistical analysis of the
HeII transverse proximity effect. Our results show qualitative evidence for a
large object-to-object variance: among the four foreground quasars with the
highest $\Gamma_QSO^HeII$ only one (previously known) quasar
is associated with a significant HeII transmission spike. We perform a stacking
analysis to average down these fluctuations, and detect an excess in the
average HeII transmission near the foreground quasars at $3\sigma$
significance. This statistical evidence for the transverse proximity effect is
corroborated by a clear dependence of the signal strength on
$\Gamma_QSO^HeII$. Our detection places a purely geometrical
lower limit on the quasar lifetime of $t_Q > 25\,Myr$.
Improved modeling would additionally constrain quasar obscuration and the mean
free path of HeII-ionizing photons.
Description
[1701.08769] Statistical Detection of the HeII Transverse Proximity Effect: Evidence for Sustained Quasar Activity for $>$25 Million Years
%0 Generic
%1 schmidt2017statistical
%A Schmidt, Tobias M.
%A Worseck, Gabor
%A Hennawi, Joseph F.
%A Prochaska, J. Xavier
%A Crighton, Neil H. M.
%D 2017
%K HeII activity effect proximity quasar transverse
%T Statistical Detection of the HeII Transverse Proximity Effect: Evidence
for Sustained Quasar Activity for $>$25 Million Years
%U http://arxiv.org/abs/1701.08769
%X The HeII transverse proximity effect -- enhanced HeII Ly$\alpha$~transmission
in a background sightline caused by the ionizing radiation of a foreground
quasar -- offers a unique opportunity to probe the morphology of quasar-driven
HeII reionization. We conduct a comprehensive spectroscopic survey to find
$z\sim3$ quasars in the foreground of 22 background quasar sightlines with
HST/COS HeII Ly$\alpha$~transmission spectra. With our two-tiered survey
strategy, consisting of a deep pencil-beam survey and a shallow wide-field
survey, we discover 131 new quasars, which we complement with known SDSS/BOSS
quasars in our fields. Using a restricted sample of 66 foreground quasars with
inferred HeII photoionization rates greater than the expected UV background at
these redshifts ($\Gamma_QSO^HeII > 5 \times
10^-16\,s^-1$) we perform the first statistical analysis of the
HeII transverse proximity effect. Our results show qualitative evidence for a
large object-to-object variance: among the four foreground quasars with the
highest $\Gamma_QSO^HeII$ only one (previously known) quasar
is associated with a significant HeII transmission spike. We perform a stacking
analysis to average down these fluctuations, and detect an excess in the
average HeII transmission near the foreground quasars at $3\sigma$
significance. This statistical evidence for the transverse proximity effect is
corroborated by a clear dependence of the signal strength on
$\Gamma_QSO^HeII$. Our detection places a purely geometrical
lower limit on the quasar lifetime of $t_Q > 25\,Myr$.
Improved modeling would additionally constrain quasar obscuration and the mean
free path of HeII-ionizing photons.
@misc{schmidt2017statistical,
abstract = {The HeII transverse proximity effect -- enhanced HeII Ly$\alpha$~transmission
in a background sightline caused by the ionizing radiation of a foreground
quasar -- offers a unique opportunity to probe the morphology of quasar-driven
HeII reionization. We conduct a comprehensive spectroscopic survey to find
$z\sim3$ quasars in the foreground of 22 background quasar sightlines with
HST/COS HeII Ly$\alpha$~transmission spectra. With our two-tiered survey
strategy, consisting of a deep pencil-beam survey and a shallow wide-field
survey, we discover 131 new quasars, which we complement with known SDSS/BOSS
quasars in our fields. Using a restricted sample of 66 foreground quasars with
inferred HeII photoionization rates greater than the expected UV background at
these redshifts ($\Gamma_\mathrm{QSO}^\mathrm{HeII} > 5 \times
10^{-16}\,\mathrm{s}^{-1}$) we perform the first statistical analysis of the
HeII transverse proximity effect. Our results show qualitative evidence for a
large object-to-object variance: among the four foreground quasars with the
highest $\Gamma_\mathrm{QSO}^\mathrm{HeII}$ only one (previously known) quasar
is associated with a significant HeII transmission spike. We perform a stacking
analysis to average down these fluctuations, and detect an excess in the
average HeII transmission near the foreground quasars at $3\sigma$
significance. This statistical evidence for the transverse proximity effect is
corroborated by a clear dependence of the signal strength on
$\Gamma_\mathrm{QSO}^\mathrm{HeII}$. Our detection places a purely geometrical
lower limit on the quasar lifetime of $t_\mathrm{Q} > 25\,\mathrm{Myr}$.
Improved modeling would additionally constrain quasar obscuration and the mean
free path of HeII-ionizing photons.},
added-at = {2017-02-01T11:16:39.000+0100},
author = {Schmidt, Tobias M. and Worseck, Gabor and Hennawi, Joseph F. and Prochaska, J. Xavier and Crighton, Neil H. M.},
biburl = {https://www.bibsonomy.org/bibtex/275b3137fac8fd229bf2e99d659634c94/miki},
description = {[1701.08769] Statistical Detection of the HeII Transverse Proximity Effect: Evidence for Sustained Quasar Activity for $>$25 Million Years},
interhash = {985af6089450b141ce21ced967a87dd5},
intrahash = {75b3137fac8fd229bf2e99d659634c94},
keywords = {HeII activity effect proximity quasar transverse},
note = {cite arxiv:1701.08769Comment: 27 pages, 19 figures, submitted to ApJ},
timestamp = {2017-02-01T11:16:39.000+0100},
title = {Statistical Detection of the HeII Transverse Proximity Effect: Evidence
for Sustained Quasar Activity for $>$25 Million Years},
url = {http://arxiv.org/abs/1701.08769},
year = 2017
}