Far-Infrared Properties of the Bright, Gravitationally Lensed Quasar J0439+1634 at z=6.5

Abstract

We present IRAM/NOEMA, JCMT/SCUBA-2 and VLA observations of the most distant known gravitationally lensed quasar J0439+1634 at z = 6.5. We detect strong dust emission, [CII] 158 $\hat{I}¼$m, [CI] 369 $\hat{I}¼$m, [OI] 146 $\hat{I}¼$m, CO(6-5), CO(7-6), CO(9-8), CO(10-9), H${}_2$O $3_{1,2}-2_{2,1}$, and H${}_2$O $3_{2,1}-3_{1,2}$ lines as well as a weak radio continuum. The strong [CII] line yields a systemic redshift of the host galaxy to be z=6.5188$\pm$0.0001. The magnification makes J0439+1634 the far-infrared (FIR) brightest quasar at z > 6 known, with the brightest [CII] line yet detected at this redshift. The FIR luminosity is (3.4$\pm$0.2)$\times$10${}^{13}$ $\hat{I}{¼}^{-1}$ $L_{\odot }$, where $\hat{I}¼$ $\sim$ 2.6 - 6.6 is the magnification of the host galaxy, estimated based on the lensing configuration from HST imaging. We estimate the dust mass to be (2.2$\pm$0.1)$\times$10${}^9$ $\hat{I}{¼}^{-1}$ $M_{\odot }$. The CO Spectral Line Energy Distribution using four CO lines is best fit by a two-component model of the molecular gas excitation. The estimates of molecular gas mass derived from CO lines and atomic carbon mass are consistent, in the range of 3.9 - 8.9 $\times$10${}^{10}\hat{I}{¼}^{-1}$ $M_{\odot }$. The [CII]/[CI], [CII]/CO, and [OI]/[CII] line luminosity ratios suggest a photodissociation region model with more than one component. The ratio of H${}_2$O $3_{2,1}-3_{1,2}$ line luminosity to $L_{\mathrm{TIR}}$ is consistent with values in local and high redshift ultra-/hyper-luminous infrared galaxies. The VLA observations reveal an unresolved radio continuum source, and indicate that J0439+1634 is a radio quiet quasar with R = 0.05 - 0.17.

13 pages, 6 figures. Accepted by ApJ