First thing we did is run the RHT algorithm (some reasonable parameters) on each of the HI data slices (binned at 4x 0.736 = 3 km/s) relevant to the fibers. Then we made masks from each of those RHT results. In particular, we chose the angle range that corresponded to the HI fiber direction, and integrated the RHT, and set a threshold of 0.1 to make a bitmask. This gives a reasonable mask that “finds” the fibers. Then, using dialation, we make an “off” mask for each velocity slice. We then concatenate these masks. On masks are shown in red, off in blue below.
We then take the WISE map and smooth it to the Planck resolution. We try to be very careful to get it just right, as it the results are sensitive to this. We then find the average flux in the WISE map in the fibers / flux in the off mask. Same for Planck, and the total HI column. We exclude the top of the region where there seems to be some dark H2.
We find that the total HI is enhanced a little in this region, as expected; about 1.5%. Planck dust emission is somewhat more enhanced than this (1.9%) and wise is more than twice as enhanced (3.8%). This indicates that the fibers are more dusty than the surrounding gas, and that they are especially enhanced in small grain / PAH 12 micron emission.
CAVEATS: haven’t smoothed the GALFA-HI data. Not totally sure how sensitive this is to RHT parameters. Also not sure how sensitive it is to getting WISE smoothing dead right.