We present the
We report the discovery of MAGAZ3NE J095924+022537, a spectroscopically confirmed protocluster at
 Award ID(s):
 1815475
 NSFPAR ID:
 10362694
 Publisher / Repository:
 DOI PREFIX: 10.3847
 Date Published:
 Journal Name:
 The Astrophysical Journal
 Volume:
 926
 Issue:
 1
 ISSN:
 0004637X
 Format(s):
 Medium: X Size: Article No. 37
 Size(s):
 Article No. 37
 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 thermal electron energization in 1D and 2D particleincell simulations of quasiperpendicular, lowbeta (
β _{p}= 0.25) collisionless ion–electron shocks with mass ratiom _{i}/m _{e}= 200, fast Mach number –4, and upstream magnetic field angle ${\mathcal{M}}_{\mathrm{ms}}=1$θ _{Bn}= 55°–85° from the shock normal . It is known that shock electron heating is described by an ambipolar, $\stackrel{\u02c6}{\mathit{n}}$ parallel electric potential jump, ΔB ϕ _{∥}, that scales roughly linearly with the electron temperature jump. Our simulations have –0.2 in units of the preshock ions’ bulk kinetic energy, in agreement with prior measurements and simulations. Different ways to measure $\mathrm{\Delta}{\varphi}_{\parallel}/(0.5{m}_{\mathrm{i}}{{u}_{\mathrm{sh}}}^{2})\sim 0.1$ϕ _{∥}, including the use of de Hoffmann–Teller frame fields, agree to tensofpercent accuracy. Neglecting offdiagonal electron pressure tensor terms can lead to a systematic underestimate ofϕ _{∥}in our lowβ _{p}shocks. We further focus on twoθ _{Bn}= 65° shocks: a ( ${\mathcal{M}}_{\mathrm{s}}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}4$ ) case with a long, 30 ${\mathcal{M}}_{\mathrm{A}}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}1.8$d _{i}precursor of whistler waves along , and a $\stackrel{\u02c6}{\mathit{n}}$ ( ${\mathcal{M}}_{\mathrm{s}}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}7$ ) case with a shorter, 5 ${\mathcal{M}}_{\mathrm{A}}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}3.2$d _{i}precursor of whistlers oblique to both and $\stackrel{\u02c6}{\mathit{n}}$ ;B d _{i}is the ion skin depth. Within the precursors,ϕ _{∥}has a secular rise toward the shock along multiple whistler wavelengths and also has localized spikes within magnetic troughs. In a 1D simulation of the , ${\mathcal{M}}_{\mathrm{s}}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}4$θ _{Bn}= 65° case,ϕ _{∥}shows a weak dependence on the electron plasmatocyclotron frequency ratioω _{pe}/Ω_{ce}, andϕ _{∥}decreases by a factor of 2 asm _{i}/m _{e}is raised to the true proton–electron value of 1836. 
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