Radio continuum observations of dwarf–dwarf galaxy mergers, such as NGC 1487, provide crucial insights into magnetic field amplification and cosmic ray propagation during galactic assembly. Dwarf galaxies are important laboratories for studying cosmic magnetism because they can maintain strong magnetic fields via the action of turbulent dynamo despite their low mass and weak gravitational potential. Taziaux et al. utilise multi-band radio continuum data from MeerKAT L-band (1.28 GHz) and the Australia Telescope Compact Array (ATCA) L/S (2.1 GHz), C (5.5 GHz), and X-bands (9 GHz) in order to analyse the magnetic field configuration using polarisation and rotation measure (RM) synthesis.

The figure above shows, from left to right, the total intensity maps at 1.28 GHz of NGC 1487 observed with MeerKAT, and at 2.1 GHz, 5.5 GHz, and 9 GHz observed with ATCA. At 1.28 GHz, the diffuse emission extends up to the base of the tidal arms. At higher frequencies (up to 9 GHz), the brightest compact regions, which had been previously identified, remain detectable. These regions are predominantly ionised by ongoing star formation and exhibit relatively low dust content: the two most prominent radio-emitting regions correspond to ionized HII regions. The radio continuum traces recent star formation, with low-frequency emission dominated by synchrotron radiation from cosmic ray electrons and higher-frequency emission increasingly contributed by free–free (or Bremsstrahlung) emission. The combined emission provides a complementary, dust-unbiased probe of star formation activity. Observations of the dwarf–dwarf merger NGC 1487 show that even low-mass galaxy mergers, likely the building blocks of larger galaxies in the early Universe, can rapidly amplify and produce coherent large-scale magnetic field structures, highlighting their key contribution in the early magnetisation of galaxies.