We present the
We report new radio observations of SDSS J090122.37+181432.3, a strongly lensed starforming galaxy at
 NSFPAR ID:
 10539542
 Publisher / Repository:
 DOI PREFIX: 10.3847
 Date Published:
 Journal Name:
 The Astrophysical Journal
 Volume:
 972
 Issue:
 2
 ISSN:
 0004637X
 Format(s):
 Medium: X Size: Article No. 147
 Size(s):
 Article No. 147
 Sponsoring Org:
 National Science Foundation
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Abstract z ≈ 6 type1 quasar luminosity function (QLF), based on the PanSTARRS1 (PS1) quasar survey. The PS1 sample includes 125 quasars atz ≈ 5.7–6.2, with −28 ≲M _{1450}≲ −25. With the addition of 48 fainter quasars from the SHELLQs survey, we evaluate thez ≈ 6 QLF over −28 ≲M _{1450}≲ −22. Adopting a double power law with an exponential evolution of the quasar density (Φ(z ) ∝ 10^{k(z−6)};k = −0.7), we use a maximum likelihood method to model our data. We find a break magnitude of , a faintend slope of ${M}^{*}={26.38}_{0.60}^{+0.79}\phantom{\rule{0.25em}{0ex}}\mathrm{mag}$ , and a steep brightend slope of $\alpha ={1.70}_{0.19}^{+0.29}$ . Based on our new QLF model, we determine the quasar comoving spatial density at $\beta ={3.84}_{1.21}^{+0.63}$z ≈ 6 to be . In comparison with the literature, we find the quasar density to evolve with a constant value of $n({M}_{1450}<26)={1.16}_{0.12}^{+0.13}\phantom{\rule{0.25em}{0ex}}{\mathrm{cGpc}}^{3}$k ≈ −0.7, fromz ≈ 7 toz ≈ 4. Additionally, we derive an ionizing emissivity of , based on the QLF measurement. Given standard assumptions, and the recent measurement of the mean free path by Becker et al. at ${\u03f5}_{912}(z=6)={7.23}_{1.02}^{+1.65}\times {10}^{22}\phantom{\rule{0.25em}{0ex}}\mathrm{erg}\phantom{\rule{0.25em}{0ex}}{\mathrm{s}}^{1}\phantom{\rule{0.25em}{0ex}}{\mathrm{Hz}}^{1}\phantom{\rule{0.25em}{0ex}}{\mathrm{cMpc}}^{3}$z ≈ 6, we calculate an Hi photoionizing rate of Γ_{H I}(z = 6) ≈ 6 × 10^{−16}s^{−1}, strongly disfavoring a dominant role of quasars in hydrogen reionization. 
Abstract We measure the COtoH_{2}conversion factor (
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