| Name: | RIYA MULLICK |
| Affiliation: | IIT Kanpur |
| Conference ID : | ASI2024_325 |
| Title : | AGN or hidden starburst in Post-Starburst galaxies? - A low radio-frequency view |
| Authors : | Riya Mullick, Amitesh Omar |
| Authors Affiliation: | 1 Indian Institute of Technology Kanpur, Kanpur-208016, India |
| Mode of Presentation: | Poster |
| Abstract Category : | Galaxies and Cosmology |
| Abstract : | Post Starburst (PSB) galaxies have very weak or no nebular emission lines indicating little to no ongoing star formation. At the same time, presence of Balmer absorption lines indicate a population of intermediate mass A or F type stars formed within a recent past. The PSB galaxies can therefore be studied to identify possible mechanisms of star formation quenching in galaxies. Radio continuum studies of PSB galaxies can uniquely address two important questions - Is there a heavily dust-obscured ongoing star formation undetected in optical bands? Is there an AGN that might have quenched star formation in the past? Earlier studies of PSB galaxies at 1.4 GHz were limited as radio detection in the VLA-FIRST data were found to be rare (around 2%). We searched for emission from PSB galaxies using the recent 144 MHz LOFAR images and detected 104 out of 1204 PSB galaxies (~8.6%) with radio emission above ~0.4 mJy. These PSB galaxies are at redshifts between 0.02 and 0.4. No significant radio far-infrared correlation using 60 μm IRAS data was noticed for these PSB galaxies. The 144 MHz radio luminosity was also not correlated with luminosity at other wave bands from optical to far-infrared. However, the fraction of radio-detected PSB galaxies showed a clear trend with absolute magnitude and colors in optical and Wide-field Infrared Survey Explorer (WISE) mid-infrared bands. We found that a chance of detection in radio PSB increases with more luminous galaxies, (u − r) bluer galaxies, and (w1 − w2) redder galaxies. Absence of a radio far-infrared correlation indicates that the radio emission in PSB galaxies is dominated by AGN. Our analysis suggests that the PSB galaxies are unlikely to have an extensive dust-obscured ongoing star formation. These results could be uniquely derived using multi-wavelength data and turn out to be crucial in understanding evolution of PSB galaxies. |
