SIMBAD references

We utilize a modified astrochemistry code that includes cosmic-ray (CR) attenuation in situ to quantify the impact of different CR models on the CO-to-H₂ and CI-to-H₂ conversion factors, X_CO and X_CI, respectively. We consider the impact of CRs accelerated by accretion shocks, and show that clouds with star formation efficiencies greater than 2% have X_CO = (2.5 ± 1) x 10²⁰ cm^–2(K km s^–1)^–1, consistent with Milky Way observations. We find that changing the CR ionization rate from external sources from the canonical ζ ≃ 10^–17 to ζ ≃ 10^–16 s^–1, which better represents observations in diffuse gas, reduces X_CO by 0.2 dex for clusters with surface densities below 3 g cm^–2. We show that embedded sources regulate X_CO and decrease its variance across a wide range of surface densities and star formation efficiencies. Our models reproduce the trends of a decreased X_CO in extreme CR environments. X_CI has been proposed as an alternative to X_CO due to its brightness at high redshifts. The inclusion of internal CR sources leads to 1.2 dex dispersion in X_CI ranging from 2 x 10²⁰ < X_CI < 4 x 10²¹ cm^–2 (K km s^–1)^–1. We show that X_CI is highly sensitive to the underlying CR model.