Evidence for C  ii diffuse line emission at redshift z ∼ 2.6

Journal Article · Mon Aug 12 00:00:00 EDT 2019 · Monthly Notices of the Royal Astronomical Society: Letters

DOI:https://doi.org/10.1093/mnrasl/slz126· OSTI ID:1560910

Yang, Shengqi; Pullen, Anthony R.; Switzer, Eric R.

ABSTRACT C ii is one of the brightest emission lines from star-forming galaxies and is an excellent tracer for star formation. Recent work measured the C ii 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 $${I}_{{\text C}\,\rm {\small II}}=6.6^{+5.0}_{-4.8}\times {10}^{4}$$ Jy sr−1 at $$95\,{\text{per cent}}$$ confidence level. 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. This excess is consistent with redshifted C ii emission, in which case we report $$b_{{\text C} \,\rm {\small II}}I_{{\text C} \,\rm {\small II}} =2.0^{+1.2}_{-1.1}\times 10^5$$ Jy sr−1 at $$95\ {\text {per cent}}$$ confidence level, which strongly favours many collisional excitation models of C ii emission. Our detection shows strong evidence for a model with a non-zero C ii parameter, though line intensity mapping observations at high spectral resolution will be needed to confirm this result.

• Sponsoring Organization: USDOE
• OSTI ID: 1560910
• Journal Information: Monthly Notices of the Royal Astronomical Society: Letters, Journal Name: Monthly Notices of the Royal Astronomical Society: Letters Vol. 489 Journal Issue: 1; ISSN 1745-3925
• Publisher: Oxford University Press
• Country of Publication: United Kingdom
• Language: English