Search for cold and hot gas in the ram pressure stripped Virgo dwarf galaxy IC 3418

We present IRAM 30 m sensitive upper limits on CO emission in the ram pressure stripped dwarf Virgo galaxy IC 3418 and in a few positions covering H ii regions in its prominent 17 kpc UV/Hα gas-stripped tail. In the central few arcseconds of the galaxy, we report a possible marginal detection of about 1 × 106 M⊙ of molecular gas (assuming a Galactic CO-to-H2 conversion factor) that could correspond to a surviving nuclear gas reservoir. We estimate that there is less molecular gas in the main body of IC 3418, by at least a factor of 20, than would be expected from the pre-quenching UV-based star formation rate assuming the typical gas depletion timescale of 2 Gyr. Given the lack of star formation in the main body, we think the H2-deficiency is real, although some of it may also arise from a higher CO-to-H2 factor typical in low-metallicity, low-mass galaxies. The presence of H ii regions in the tail of IC 3418 suggests that there must be some dense gas; however, only upper limits of