Abstract Details

Name: Prerana Biswas
Affiliation: PhD student, Joint Astronomy Programme, IISc Bangalore
Conference ID: ASI2020_444
Title : Kinematics of nearby spiral galaxies with different inclination angles using 21cm HI interferometric data
Authors and Co-Authors : Prerana Biswas, Dr. Nirupam Roy
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : Tully and Fisher, 1977 showed that there exists a tight correlation between the total luminosity and circular velocities the galaxies. This relation is very important because the circular velocity depends upon the total mass that is the baryonic mass plus the dark matter mass of the galaxies and the luminosity depends on the only total baryonic mass of the galaxies. While deriving this relation, the velocities have been represented in different forms depending upon the availability of the data. For most of the cases velocities that are used to derive HI profile, are the line of sight velocities and observed from the single dishes, and can not be corrected for inclination angles. Here, from a sample of twelve nearby galaxies, each with different inclination angles, observed in 21cm by GMRT we have analysed the interferometric data to deduce 3D image-cubes of these galaxies, flux as a function of sky position RA-DEC and velocities. The cubes are used to extract HI line profile and to fit a tilted ring-like model of galaxies to estimate parameters like inclination angles, scale height etc. and to simulate the rotation curve. From these, all forms of circular velocities are derived and then compared to show that, velocity of the galaxy where rotation curve gets flattened, gives tightest baryonic Tully-Fisher relation which is consistent with other observations. Further, the different forms of line of sight velocities are corrected for the inclination angles, and we tried to show variations of these different forms of velocities with different inclination angles. Besides that this interferometric HI data when combined with stellar observations, can give us profiles for different mass components of galaxies. As some of this galaxies are with large inclination angles, we can probe the non-equilibrium gas flows from the perpendicular directions of the galactic discs with them.