Presentation #141.08 in the session Intergalactic Medium, QSO Absorption Line Systems — iPoster Session.
Gravitational lensing occurs when a celestial body with large gravitational potential distorts light emitted from an object behind that body. This creates warped and/or multiple images of the background object. Gravitational lensing allows astronomers to use multiply imaged objects to investigate intervening cosmic gas and to probe small spatial scales (which is not possible when observing single background sources) in the circumgalactic medium (CGM), the large reservoir of gas that surrounds a galaxy and fuels star formation. Here we present Keck Cosmic Web Imager (KCWI) Integral Field Unit (IFU) spectroscopic observations of J1004+4112, a quadruply lensed quasar system at z = 1.73, to probe the circumgalactic medium of the lensing galaxy cluster at z = .68 and galaxies at z < 1.73. We study the variation of 104 K cool gas in the halo of the galaxy cluster seen in Mg II absorption at ~ 38–70 kpc from the cluster center. Using the four quasar sightlines, we further study the spatial variation in absorption strengths of five additional absorbers at 0.26 < z < 0.83. We quantify the spatial coherence of these absorber systems by computing fractional differences in equivalent width between different sightlines. By examining the differences between absorption lines, we constrain the coherence length of the absorbers to < 20 kpc.