Intensity Mapping (IM) of various emission lines such as HI, Ly-alpha, CO, and [CII], is a promising technique to probe the properties of the Universe over multiple epochs, from the cosmic dawn and epoch of reionization down to lower redshifts. With a beam much larger than a typical galaxy, an IM experiment measures the aggregate emission from a large number of galaxies, requiring neither the high sensitivity or high resolution of a traditional galaxy survey. The measured intensity of a line in a given volume depends both on the detailed astrophysical processes in the emission region as well as the underlying dark matter density and the details of cosmic evolution. Thus IM surveys contain a wealth of cosmological and astrophysical information which is difficult to obtain using other methods.
As several IM experiments, targeting different emission lines in various redshift ranges (see Figure), are set to come online, this is an excellent time to bring the community together to discuss recent advances in theory, observation and data analysis, and to discuss the challenges we face looking forward. This will be the second in a series of workshops intended to initiate and advance collaborative projects and aiming to align and consolidate the efforts in the field looking forward. The workshop will encourage active participation from all participants and provide ample time for discussion and exchange of ideas.
Figure: A representative list of current and proposed intensity mapping experiments (differentiated by color and grouped by the boundary shape according to the targeted emission-line). The horizontal axis shows the redshift range of each experiment and the vertical axis indicates the range between the maximum resolution of the instrument and the total sky coverage. The experiments shown are COPSSII, YTLA2 and COMAP which will target CO at moderate redshifts, CONCERTO and TIME-Pilot which will go after [C II] at reionization redshifts, GBT, CHIME and HERA which target 21cm and SPHEREx which will have access to Hα and Lyα over a wide range of redshifts at high angular resolution and considerable sky coverage.