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_s = 2.377 ± 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_r as a function of sight-line separation. We measure differences in W_(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_(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_(r,1548) differences of ≈5%–80% within transverse distances of 3 kpc. These spatial variations are consistent with those measured in intervening absorbers detected toward lensed quasars drawn from the literature, in which W_(r,2796) and W_(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.

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