SIMBAD references

The formaldehyde megamaser emission has been mapped for the three host galaxies IC 860, IRAS 15107+0724 and Arp 220. Elongated emission components are found at the nuclear centres of all galaxies with an extent ranging between 30 and 100 pc. These components are superposed on the peaks of the nuclear continuum. Additional isolated emission components are found superposed in the outskirts of the radio continuum structure. The brightness temperatures of the detected features ranges from 0.6 to 13.4 x 10⁴ K, which confirms their masering nature. The masering scenario is interpreted as amplification of the radio continuum by foreground molecular gas that is pumped by far-infrared radiation fields in these starburst environments of the host galaxies.