Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z = 2.377

Abstract

We present Keck Cosmic Web Imager spectroscopy of the four putative images of the lensed quasar candidate J014710+463040 recently discovered by Berghea et al. The data verify the source as a quadruply lensed, broad absorption-line quasar having ${z}_{{\rm{S}}}=2.377\,\pm \,0.007$. We detect intervening absorption in the Fe ii λλ2586, 2600, Mg ii λλ2796, 2803, and/or C iv λλ1548, 1550 transitions in eight foreground systems, three of which have redshifts consistent with the photometric-redshift estimate reported for the lensing galaxy (z L ≈ 0.57). The source images probe these absorbers over transverse physical scales of ≈0.3–22 kpc, permitting assessment of the variation in metal-line equivalent width ${W}_{{\rm{r}}}$ as a function of sight-line separation. We measure differences in ${W}_{{\rm{r}},2796}$ of <40% across most of the sight-line pairs subtending 8–22 kpc, suggestive of a high degree of spatial coherence for the Mg ii-absorbing material. ${W}_{{\rm{r}},2600}$ varies by >50% over the same scales across the majority of sight-line pairs, while C iv absorption exhibits a wide range in ${W}_{{\rm{r}},1548}$ differences of ≈5%–80% within transverse distances of lesssim3 kpc. These spatial variations are consistent with those measured in intervening absorbers detected toward lensed quasars drawn from the literature, in which ${W}_{{\rm{r}},2796}$ and ${W}_{{\rm{r}},1548}$ vary by ≤20% in 35 ± 7% and 47 ± 6% of sight lines separated by <10 kpc, respectively. J014710+463040 is one of only a handful of z > 2 quadruply lensed systems for which all four source images are very bright (r = 15.4–17.7 mag) and are easily separated in ground-based seeing conditions. As such, it is an ideal candidate for higher-resolution spectroscopy probing the spatial variation in the kinematic structure and physical state of intervening absorbers.