Decimetre Studies of Neutral Gas in Starburst Galaxies

摘要

We will review observations of neutral gas in starburst galaxies, concentrating mainly on atomic hydrogen, but also including some discussion of OH molecules. In a number of starbursts, OH maser emission gives valuable insights into the properties and dynamics of localised regions of neutral gas, however thermal emission from neutral gas usually has a relatively low excitation temperature, and observations of this gas is severely limited by the sensitivity of current decimetre arrays and can only be observed at relatively low angular resolution (5–10 arcsec).Absorption measurements, however, are only limited by the brightness of the synchrotron continuum background and hence it is possible to measure the distribution of absorbing neutral gas on scales as small as a few milliarcseconds. We will review progress in this area ranging from detailed studies of nearby objects such as M82, to distant, more luminous starbursts such as Arp220. We also will discuss the role of neutral gas in testing for the presence of an active galactic nucleus within a starburst.