%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 }