The ALMA REBELS Survey: The First Infrared Luminosity Function Measurement at <b>z ∼ 7</b>

Abstract We present the first observational infrared luminosity function (IRLF) measurement in Epoch of Reionization (EoR) based on a UV-selected galaxy sample with ALMA spectroscopic observations. Our analysis is large program Era Bright Emission Line Survey (REBELS), which targets 42 galaxies at z = 6.4-7.7 [CII] 158$\hbox{$\mu $m}$ line scans. 16 sources exhibit dust detection, 15 are also spectroscopically confirmed through line. The IR luminosities range from log LIR/L⊙ 11.4 to 12.2. Using UVLF as proxy derive effective volume for each our target sources, we IRLF estimates, both detections and full including upper limits. resulting IRLFs well reproduced by Schechter characteristic $\log L_{*}/L_\odot =11.6^{+0.2}_{-0.1}$. results broad agreement average predicted simulations ∼ 7. Conversely, lie significantly below lower redshift suggesting rapid evolution 4 7, into reionization epoch. inferred obscured contribution cosmic star-formation rate density 7 amounts $\mathrm{log(SFRD/M_{\odot }/yr/Mpc^{3}) -2.66^{+0.17}_{-0.14} }$ least ∼10% UV-based estimates. conclude that presence already abundant EoR discuss possibility unveiling larger samples dusty future JWST