Speaker
Description
Radio continuum emission from galaxies at gigahertz frequencies can be used as an extinction-free tracer of star formation. However, at frequencies of a few hundred megahertz, there is evidence for low-frequency spectral flattening. We wish to better understand the origin of this low-frequency flattening and, to this end, perform a spatially resolved study of the nearby spiral galaxies M51 and M101. This is an important use case for LOFAR LBA observations.
For the analysis of M51, we used radio continuum intensity maps between 54 and 8350 MHz at eight different frequencies. We found that cosmic-ray ionisation losses play an important role in the low-frequency spectral flattening alongside free-free absorption. We are working on a similar analysis in M101, using five radio maps between 54 and 4850 MHz. We would like to verify the importance of ionisation losses and focus on separate giant HII regions which can be resolved in M101.
