| Abstract : | The Spitzer IR Spectrograph observations of FR-I & FR-II radio galaxies at redshift <0.22 have detected pure rotational emission lines from warm (100–1500 K) molecular H2 gas. It results in a new class of radio galaxies having large H2 luminosities of the order of 10^40-10^42 erg/s and large L(H2) to L(PAH) ratios; of 0.03–4 or greater. These galaxies are called radio molecular hydrogen emission galaxies (radio MOHEGs). Despite having a significant amount of molecular hydrogen gas, these galaxies show insufficiency in star formation, with an inadequate amount of star formation rates. It is suggested that galaxy collisions or cooling flows drive the molecular gas in MOHEGs, further heated by radio-jet feedback via shocks or cosmic rays.
Furthermore, most of these galaxies appear to have stellar disks, dust disks, or dust lanes. We have detailed studies in optical and IR regions on MOHEGs. The low-frequency radio continuum, redshifted H1 studies, and higher spatial resolution of the H2 emission
region and its kinematics will give further insights into the
radio-jet feedback mechanism. Moreover, it would help us understand the kinematics of unsettled/turbulent phase molecular gases in these galaxies. |
