We present total intensity maps of the galaxy NGC 2997 at frequencies 1435.1MHz (λ21cm) and 1652.4MHz (λ18cm) observed with the Very Large Array (VLA). The high spatial resolution allows us to distinguish two domina...We present total intensity maps of the galaxy NGC 2997 at frequencies 1435.1MHz (λ21cm) and 1652.4MHz (λ18cm) observed with the Very Large Array (VLA). The high spatial resolution allows us to distinguish two dominant arms. Using multi-frequency data, we separate the thermal and non-thermal contributions to the radio emission. The thermal emission is about 35% of the total emission at λ3 cm. We use it to estimate a space-averaged thermal electron density, (ne) - 0.049 cm-3. The spectral index map shows that the optical arms and the central part of the galaxy have flatter spectra. We also determine the flux densities of 22 radio sources in the field-of-view of 25'.展开更多
文摘We present total intensity maps of the galaxy NGC 2997 at frequencies 1435.1MHz (λ21cm) and 1652.4MHz (λ18cm) observed with the Very Large Array (VLA). The high spatial resolution allows us to distinguish two dominant arms. Using multi-frequency data, we separate the thermal and non-thermal contributions to the radio emission. The thermal emission is about 35% of the total emission at λ3 cm. We use it to estimate a space-averaged thermal electron density, (ne) - 0.049 cm-3. The spectral index map shows that the optical arms and the central part of the galaxy have flatter spectra. We also determine the flux densities of 22 radio sources in the field-of-view of 25'.
