A radio study of the superwind galaxy NGC 1482 |
| |
| Authors: | Ananda Hota D J Saikia |
| |
| Institution: | Joint Astronomy Programme, Indian Institute of Science, Bangalore 560 012, India;National Centre for Radio Astrophysics, TIFR, Pune University Campus, Post Bag 3, Pune 411 007, India |
| |
| Abstract: | We present multifrequency radio continuum as well as H i observations of the superwind galaxy NGC 1482, with both the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). This galaxy has a remarkable hourglass-shaped optical emission-line outflow as well as bipolar soft X-ray bubbles on opposite sides of the galactic disc. The low-frequency, lower-resolution radio observations show a smooth structure. From the non-thermal emission, we estimate the available energy in supernovae, and examine whether this would be adequate to drive the observed superwind outflow. The high-frequency, high-resolution radio image of the central starburst region located at the base of the superwind bi-cone shows one prominent peak and more extended emission with substructure. This image has been compared with the infrared, optical red continuum, Hα, and soft and hard X-ray images from Chandra to understand the nature and relationship of the various features seen at different wavelengths. The peak of the infrared emission is the only feature that is coincident with the prominent radio peak, and possibly defines the centre of the galaxy.
The H i observations with the GMRT show two blobs of emission on opposite sides of the central region. These are rotating about the centre of the galaxy and are located at ～2.4 kpc from it. In addition, these observations also reveal a multicomponent H i absorption profile against the central region of the radio source, with a total width of ～250 km s?1. The extreme blue- and redshifted absorption components are at 1688 and 1942 km s?1, respectively, while the peak absorption is at 1836 km s?1. This is consistent with the heliocentric systemic velocity of 1850 ± 20 km s?1 , estimated from a variety of observations. We discuss possible implications of these results. |
| |
| Keywords: | galaxies: active galaxies: individual: NGC 1482 galaxies: kinematics and dynamics galaxies: starburst radio continuum: galaxies radio lines: galaxies |
|
|
