Dense Molecular Gas In M82 From MALATANG Source

There is a close relationship between the dense molecular gas and star formation in galaxies.In order to study the star formation in galaxies,we observe and analyze the spectral lines of the dense molecular gas in galaxies.MALATANG(Mapping the Dense Molecular Gas in the Strongest Star forming Galaxies)is a large program of the East Asian Observatory James Clerk Maxwell Telescope,which acquired HCN J=4-3 and HCO~+J=4-3 line of 23 nearby infrared-bright galaxies.M82 is a nearby starburst galaxy whose central region is an extremely active star forming region.M82is also an observation source for the MALATANG project.We performed 150 and100 minutes observations on the HCN J=4-3 and HCO+J=4-3 lines of M82,respectively.In this work,M82 is taken as the research object,and the contour map of all the observation positions of M82 is drawn.This work uses CLASS and JCMT software starlink for data processing,For JCMT raw data,we running ORAC_DR pipeline to obtain cube data,using the re-extract method and masking method to further process the cube data.After preliminary processing,the authors found that only dense gas emission signals were present in the central region of the galaxy,and signals of dense gas could not be found in the outer regions of the galaxy.In order to determine whether there are weak and dense gas signals that are submerged by noise in the outer regions of the galaxy,the author used the stacking method to stack the M82 galaxies away from the center of the region where no dense gas signals were detected.The stack results show that the ring is near the center of the galaxy.There is a weaker dense gas signal in the area,and for the outer area farther away from the center,even if the stacking process is performed,the trace of the dense gas signal cannot be found.Therefore,the authors judge that the core area of the M82 galaxies is an active star-forming area,while the far-centered galaxies are a very calm and inactive area.M82 itself should be a calm galaxies with low star formation activity,and the interaction with M81 stimulates intense star formation in the core region of M82.