Dependence of radio halo properties on star formation activity and galaxy mass

作者：Dahlem M^*; Lisenfeld U; Rossa J

来源：Astronomy & Astrophysics, 2006, 457(1): 121-131.

DOI：10.1051/0004-6361:20054787

• ISM : general
• galaxies : spirals
• galaxies : evolution
• galaxies : halos
• galaxies : starburst
• radio continuum : galaxies

We investigate the relation between the existence and size of radio halos, which are believed to be created by star formation ( SF) related energy input into the interstellar medium, and other galaxy properties, most importantly star formation activity and galaxy mass. Based on radio continuum and Ha observations of a sample of seven late-type spiral galaxies we find a direct, linear correlation of the radial extent of gaseous halos on the size of the actively star-forming parts of the galaxy disks. Data of a larger sample of 22 galaxies indicate that the threshold energy input rate into the disk ISM per unit surface area for the creation of a gaseous halo depends on the mass surface density of the galaxy, in the sense that a higher threshold must be surpassed for galaxies with a higher surface density. Because of the good prediction of the existence of a radio halo from these two parameters, we conclude that they are important, albeit not the only contributors. The compactness of the SF-related energy input is also found to be a relevant factor. Galaxies with relatively compact SF distributions are more likely to have gaseous halos than others with more widespread SF activity. These results quantify the so-called "break-out" condition for matter to escape from galaxy disks, as used in all current models of the interstellar medium and first defined by Norman & Ikeuchi (1989).

• 出版日期2006-10
• 单位CSIRO