Evidence for CII diffuse line emission at redshift $z\sim2.6$

Understand

CII is one of the brightest emission lines from star-forming galaxies and is an excellent tracer for star formation.

• Recent work measured the CII emission line amplitude for redshifts $2<z<3.2$ by cross-correlating Planck High Frequency Instrument emission maps with tracers of overdensity from the Baryon Oscillation Spectroscopic Sky Survey, finding $I_{\mathrm{CII}}=6.6^{+5.0}_{-4.8}\times 10^4$ Jy/sr at $95\%$ confidence.
• In this paper, we present a refinement of this earlier work by improving the mask weighting in each of the Planck bands and the precision in the covariance matrix.
• We report a detection of excess emission in the 545 GHz Planck band separate from the cosmic infrared background (CIB) present in the 353-857 GHz Planck bands.