AR-2019-2020

Figure 10: Left: The broad r-band image, tracing the stellar continnum light in the galaxy. Right: The stellar continuum subtracted H α emission line image, tracing ionized gas or site of star-forming regions in the galaxy. (Both the images towards the south-west direction show a tidal tail like feature related to galaxy tidal interaction process) black hole in AGN. Tek. P. Adhikari, and collaborators carried out a comparative analysis of X-ray spectrum of NGC 3783 during unobscured and obscured states observations. The study of spectral -timing properties of the X-ray obscurer in NGC 3783 enabled them to put independent constraints on the density and location of the obscuring gas. What shapes the absorption measure distribution in AGN outflows? The absorption measure distribution (AMD) in the X-ray outflows of Seyfert active galactic nuclei describes the distribution of absorbing column density as a function of ionization level of the gas. The shape of this distribution provides the information regarding the distribution of ionized materi- als in the environment of super-massive black hole. T. P. Adhikari and collaborators investigated such distribution and tested a range of photoionization models against the overall shape of the AMD as observed in Seyfert galaxies. In particular, they demonstrated that the shape of the distribution of ionized material is determined by both the spectral energy distribution (SED) of radiation that enters the material, and its density. The model that best follows the observed distribution of AMD is one wherein the gas density of the absorbing outflow is of the order of 10 12 cm − 3 , irradiated by an SED whose optical/UV power is 100 times higher than the X-ray power (see Fig. 11). Galaxies In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, Sumana Nandi, D.J. Saikia , Rupak Roy , Pratik Dabhade , et al. have identified such sources with a large range of linear sizes (220 917 kpc), and hence time scales of episodic activity. They have presented high-sensitivity 607-MHz Giant Metrewave Radio Telescope (GMRT) images of 21 possible double-double radio galaxies (DDRGs) identified from the FIRST survey confirming their episodic nature. A new DDRG has been identified with a candidate quasar. The estimated age limits (11 52 Myr) are smaller than those of the large-sized ( ∼ 1 Mpc) DDRGs. The CHANG-ES galaxy sample consists of 35 nearby edge-on galaxies that have been observed