ALMA High- J CO Spectroscopy of High-redshift Galaxies. I. An Archive-based Catalog of CO Spectral Line Energy Distributions

High- J CO emission in high-redshift galaxies has been studied primarily on an individual-source basis, limiting our ability to draw population-level conclusions about molecular-gas excitation. To address this limitation, we present a catalog of CO spectroscopy based on archival data from the Atacama Large Millimeter/submillimeter Array (ALMA) for a sample of galaxies at z > 3, focusing on high- J transitions ( J up = 9–17). Combining ALMA archival data with published measurements, we compile CO spectral line energy distributions (SLEDs) for 38 well-studied systems spanning z ≃ 3.1–6.9, including five hot dust-obscured galaxies (Hot DOGs), 17 submillimeter-bright galaxies (SMGs), and 16 optically selected quasars. The class-median SLEDs rise steeply to J up = 9 and remain approximately flat through J up ∼ 11–12. SMGs show relatively stronger low- to mid- J emission relative to CO J = 9–8, while Hot DOGs exhibit tentative evidence for higher excitation. Comparison with simple excitation models suggests that X-ray-dominated region (XDR) heating or dense, shock-heated gas can account for the extended high- J CO SLEDs. A tentative anticorrelation between the CO(9–8)-to-infrared luminosity ratio and excitation among the dusty galaxy populations suggests that the enhanced excitation in Hot DOGs may be driven by XDR heating from the activity of an obscured active galactic nucleus rather than by shocks. Because the sample is restricted to sources with detected high- J CO lines, it is biased toward highly excited systems. It nonetheless provides a reference for designing future systematic surveys of high- J CO emission with a statistically complete or flux-limited sample.