A Model of Spectral Line Broadening in Signal Forecasts for Lineintensity Mapping Experiments
Abstract
Lineintensity mapping observations will find fluctuations of integrated line emission are attenuated by varying degrees at small scales due to the width of the line emission profiles. This attenuation may significantly impact estimates of astrophysical or cosmological quantities derived from measurements. We consider a theoretical treatment of the effect of line broadening on both the clustering and shotnoise components of the power spectrum of a generic lineintensity power spectrum using a halo model. We then consider possible simplifications to allow easier application in analysis, particularly in the context of inferences that require numerous, repeated, fast computations of model lineintensity signals across a large parameter space. For the CO Mapping Array Project and the CO(10) lineintensity field at z ~ 3 serving as our primary case study, we expect a ~10% attenuation of the spherically averaged power spectrum on average at relevant scales of k ≍ 0.20.3 Mpc^{1} compared to ~25% for the interferometric Millimetrewave Intensity Mapping Experiment targeting shot noise from CO lines at z ~ 15 at scales of k ≳ 1 Mpc^{1}. We also consider the nature and amplitude of errors introduced by simplified treatments of line broadening and find that while an approximation using a single effective velocity scale is sufficient for spherically averaged power spectra, a more careful treatment is necessary when considering other statistics such as higher multipoles of the anisotropic power spectrum or the voxel intensity distribution.
 Publication:

The Astrophysical Journal
 Pub Date:
 December 2021
 DOI:
 10.3847/15384357/ac2a35
 arXiv:
 arXiv:2104.11171
 Bibcode:
 2021ApJ...923..188C
 Keywords:

 734;
 1338;
 262;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 24 pages + appendix and bibliography (33 pages total), 16 figures, 2 tables