AbstractMasers in starburst galaxies are outstanding probes of a range of phenomena related to galaxy and black hole evolution, star formation, and magnetic fields. Here I briefly discuss five related topics: (1) Galactic analog water masers in nearby galaxies; (2) multiwavelength solutions to the OH megamaser puzzle in major galaxy mergers; (3) formaldehyde anti-inversion in starburst galaxies; (4) OH spoofing in HI surveys; and (5) new discovery space in radio line surveys. New insights into the physical conditions responsible for OH megamasers, including indications of a critical molecular gas density obtained from the formaldehyde “densitometer,” will be applicable to future surveys, particularly surveys for redshifted hydrogen where OH lines arising in major galaxy mergers can “contaminate” the disk population identified by the HI 21 cm line. Blind radio spectral line surveys also offer the opportunity for unexpected discoveries of new nonthermal radio lines.
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