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Galaxies in dense environments, such as groups and clusters, experiencevarious processes by which galaxies gain and lose gas. Using data from theSDSS-IV MaNGA survey, we previously reported the discovery of a giant (6 -- 8kpc in diameter) H$\alpha$ blob, Totoro, about 8 kpc away from a pair ofgalaxies (Satsuki and Mei) residing in a galaxy group which is experiencing agroup-group merger. Here, we combine interferometric $^{12}$CO(1--0) moleculargas data, new wide-field H$\alpha$, $u$-band data, and published X-ray data todetermine the origin of the blob. Several scenarios are discussed to accountfor its multi-wavelength properties, including (1) H$\alpha$ gas being strippedfrom galaxy Satsuki by ram-pressure; (2) a separated low-surface-brightnessgalaxy; (3) gas being ejected or ionized by an active galactic nucleus (AGN);and (4) a cooling intra-group medium (IGM). Scenarios (1) and (2) are lessfavored by the present data. Scenario (3) is also less likely as there is noevidence for an active ongoing AGN in the host galaxy. We find that the CO(cold) and H$\alpha$ (warm) gas coexist with X-ray (hot) structures; moreover,the derived cooling time is within the regime where molecular and H$\alpha$ gasare expected. The coexistence of gas with different temperatures also agreeswith that of cooling gas in other systems. Our multi-wavelength resultsstrongly suggest that the CO and H$\alpha$ gas are the product of cooling fromthe IGM at its current location, i.e., cooling has occurred, and may beongoing, well outside the host-galaxy core.

SDSS-IV MaNGA: The Nature of an Off-galaxy H$\alpha$ Blob -- A Multi-wavelength View of Offset Cooling in a Merging Galaxy Group