Intracluster light ( ICL ) is believed to originate from the stars stripped from cluster galaxies .
They are no longer gravitationally bound to individual galaxies , but to the cluster , and their smooth distribution potentially makes them serve as much denser tracers of the cluster dark matter than the sparsely distributed cluster galaxies .
We present our study of the ICL in the galaxy cluster Cl 0024+17 using both Advanced Camera for Surveys ( ACS ) and Subaru data , where we previously reported discovery of a ring-like dark matter structure with gravitational lensing .
The ACS images provide much lower sky levels than ground-based data , and enable us to measure relative variation of surface brightness reliably .
This analysis is repeated with the Subaru images to examine if consistent features are recovered despite different reduction scheme and instrumental characteristics .
We find that the intracluster light profile clearly resembles the peculiar mass profile , which stops decreasing at r \sim 50 \arcsec ( \sim 265 kpc ) and slowly increases until it turns over at r \sim 75 \arcsec ( \sim 397 kpc ) .
This feature is seen in both ACS and Subaru images for nearly all available passband images while the features are in general stronger in red filters .
The consistency across different filters and instruments strongly rules out the possibility that the feature might come from any residual , uncorrected calibration errors .
In addition , our re-analysis of the cluster X-ray data shows that the peculiar mass structure is also indicated by a non-negligible ( 3.7 \sigma in Chandra and 2.4 \sigma in XMM- Newton ) bump in the intracluster gas profile when the geometric center of the dark matter ring , not the peak of the X-ray emission , is chosen as the center of the radial bin .
The location of the gas ring is closer to the center by \sim 15 \arcsec ( \sim 80 kpc ) , raising an interesting possibility that the ring-like structure is expanding and the gas ring is lagging behind perhaps because of the ram pressure if both features in mass and gas share the same dynamical origin .