Intracluster Light in Abell 2744 at Redshift 0.308: A Budget Through Cosmological Dimming

Abell 2744, a massive merging cluster at redshift 0.308 imaged deeply by the Frontier Fields programme, offers the best look at intracluster light in the distant universe, where cosmological surface-brightness dimming taxes every measurement. Adopting a total light of 2.6e12 solar luminosities within 300 kpc and a diffuse fraction of 0.11, the intracluster component carries 2.86e+11 solar luminosities and 6.29e+11 solar masses of stars, against 2.31e+12 solar luminosities remaining in galaxies. The three central galaxies together hold 4.5e11 solar luminosities, so the diffuse component amounts to 0.64 of their combined light: in this system the space between the brightest galaxies shines with nearly two-thirds as much light as the brightest galaxies themselves. Averaged within 200 kpc the diffuse light has a rest-frame surface brightness of 26.16 magnitudes per square arcsecond, which dimming by 1.17 magnitudes at this redshift degrades to an observed 27.32. Building the diffuse mass since redshift 1 requires a mean stripping rate of 157 solar masses per year sustained for four billion years. The fraction is lower than in the richest nearby clusters, and this paper examines how much of that difference is aperture, dimming, and youth rather than physics.