Constrain the CO-to-H2 conversion factor in the Abell 1795 molecular filament

Determine whether the CO-to-H2 conversion factor in the molecular gas filament of Abell 1795 is lower than the standard Milky Way value by obtaining tighter constraints on the excitation temperature and molecular-gas covering fraction.

Background

The paper derives a broad range of CO-to-H2 conversion factors for the northern molecular filament, spanning approximately 0.4–4.9 M_sun (K km s^-1 pc^2)^-1, because the inferred molecular mass depends strongly on the poorly constrained excitation temperature and covering fraction. Although the lower end is substantially below the Galactic value, the upper end is consistent with it.

The authors therefore identify improved constraints on the excitation conditions and covering fraction as necessary to establish whether the filament genuinely has a sub-Galactic conversion factor. This is important because adopting the Galactic value could overestimate the molecular gas mass, affecting interpretations of whether the radio bubble can entrain the filament.