deletions | additions       diff --git a/other_megamasers.tex b/other_megamasers.tex  index 59b1f48..e6fe146 100644  --- a/other_megamasers.tex  +++ b/other_megamasers.tex 
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A second detection of CH$_3$OH mega-masers was recently reported by \citet{chen_methanol_2015} toward the well-studied Arp 220, which is also known to harbour OH and H$_2$CO mega-maser emission. They report a detection of CH$_3$OH in the same 36.2 GHz line as \citet{wang2014_SiO_CH3OH} and at 37.7 GHz using the Australia Telescope Compact Array. The observed spectral features are narrow and their inferred luminosities are about 8 orders of magnitude greater than typical galactic CH$_3$OH masers, putting them nearly in the {\it giga}-maser regime. They also conclude that this emission arises due to shock fronts associated with outflows from the nuclear region. They find the position of the mega-masers correlate well with H$\alpha$ emission. These results suggest that CH$_3$OH mega-masers may trace larger scales than OH and H$_2$O mega-masers. Through combined detections of these three species in a system, the influence of the circumnuclear starburst on the surrounding regions could be tested.  Both detections of CH$_3$OH mega-masers come after a survey completed by \citet{darling2003_CH3OH}. The author's observed 28 known OH mega-maser hosts with Arecibo with the C-band receiver, which unfortunately limited the survey targets to redshifts greater than 0.11 due to the frequency cut-off of the receiver. The recent detections explained above are at much smaller redshifts (0.018 for Arp 220, and 0.004 for NGC 1068). It seems likely that the observations of \citet{darling2003_CH3OH} did not  have adequate sensitivities to find a detection. detect CH$_3$OH mega-masers at those redshifts.  These detections will likely spur further surveys for further detections of these masing species. As \citet{darling2012} points out, the first mega-maser detections were serendipitous, and given the widespread nature of galactic strength masers, exploratory searches will likely result in new discoveries of extragalactic masing species. If the nature of these galaxies is in any way similar to the Milky Way, star-forming galaxies should be teeming with masers, kilo-masers, and other mega-masers.