Abstract Details

Name: Souvik Manna
Affiliation: Research Scholar
Conference ID: ASI2020_237
Title : Low radio frequency spatially resolved studies of nearby galaxies
Authors and Co-Authors : Souvik manna and Subhashis Roy
Abstract Type : Oral
Abstract Category : Extragalactic Astronomy
Abstract : Magnetic fields could play important role at every scale in the star formation process from the dynamics of the galactic ISM to the fragmentation of individual star-forming cores. However, for most of the local volume galaxies of different hubble type, there is no spatially resolved map of magnetic field distribution. Therefore, we have carried out metre wavelength observations of a set of nearby galaxies with GMRT and estimated sky plane equipartition magnetic fields. We have selected a sample of 46 galaxies with angular sizes between 6' to 17' from the Local Volume Legacy (LVL) survey of galaxies within 11 Mpc (Dale et al. 2009). From our pilot observations of 7 galaxies at 325 MHz with GMRT along with their VLA archival data at 1.4 GHz, we have subtracted their thermal emissions and made spatially resolved maps of their spectral indices and magnetic fields. The magnetic fields are found to be strongest on and around their central regions and goes down by ~2-4 towards their outer parts. We have also estimated turbulent gas energy density using CO and HI data which traces molecular and atomic gas respectively. Magnetic field and turbulent gas energy densities are found to be close to their equipartition values. Magnetic field is found to vary with gas density with an average power law index of 0.46+/-0.04. We have also estimated star-formation rates using FUV and IR emission and have studied the correlation of magnetic field and star-formation rate surface density. Magnetic field is found to depend on star formation rate with a power law index of 0.30+/-0.02. Monte-Carlo simulations show that the magnetic fields for the sample galaxies vary from their equipartition values by ~25%. We are now analysing another 17 galaxies from the above sample of 46 galaxies observed with uGMRT between 300-500 MHz.