# Research Section :::info This page is a brief collection of all my present research activities. Here I put the results obtained from the various research projects, few talks/posters that I present related to those results and the resulting publications out of these projects. I will also attempt to write *popular science* level articles related to various aspects of my work. ::: --- <iframe width="660" height="415" src="https://www.youtube.com/embed/FPF1X13wbDI" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> > *This animation is an artistic impression of the inner regions of an active galaxy. The animation starts with the optical image of 3C273, a very well known quasar and zooms in up to the sub-parsec scale, where the clumps of gas known as the Broad Line Region (BLR) clouds exist embedded beneath a torus of dust.* (video Courtesy: ESO YouTube channel) --- In early [February 1963](https://earthsky.org/space/this-date-in-science-maartin-schmidt-discovers-first-known-quasar) Martin Schmidt at the California Institute of Technology, recognized that the spectrum of a radio detected source 3C 273 could be interpreted as if the source is located at red-shift 0.16. This was the first ever discovered *quasar*, short for *quasi stellar source* as it was initially known. Within a few years, a lot of such extra-galactic sources were discovered which since then are known as Active galactic Nuclei or AGN. The term quasar is now commonly used for AGN with high luminosity. Active galaxies differ from normal galaxies by the fact that they are luminous objects which outshine their own host galaxies and the high luminosity arises due to the actively accreting Super massive Black Hole (SMBH) residing at the centre. This activity provides us observational signature in all the energy bands. The accretion of matter can be described in the form of optically thick, geometrically thin accretion disk formed in the vicinity of the SMBH. Click here to [know more.](https://ned.ipac.caltech.edu/level5/Cambridge/frames.html) --- :::success ### My Ph.D. thesis is based on resolving the inner regions of these AGN through multiple wave band observations to understand the nature, structure and dynamics of matter there. ::: # Ongoing projects: This is a list of ongoing research projects I am involved in currently. - Resolving the accretion disk structure in AGN. - Understanding the dynamics of gas in the inner regions of AGN: - Microvariability study for a handful of interesting AGN: - Changing look Active Galaxies: Unraveling the AGN host and the role of environment in triggering AGN activity: - Searching for very high redshift quasars: # Other things: ## A collection of review papers: Written by eminent experts in the field, I have put together a collection of books and review papers aimed at beginner student in the field of AGN astronomy. I also go through these papers from time to time in order to understand and revise the concepts and terminology involved in the fiele of AGN research. [Click here](https://hackmd.io/@research-page/agn-review) to see these papers. ## Aperture photometry script to make things faster: We are developing a [code](https://github.com/viveikjha/aperture_photometry) to perform aperture photometry on data obtained through the 1.3m Devasthal fast optical Telescope. We are in the process of developing a photometry pipeline and this code is an integral part of the same. We aim to make this package work on data from any telescope with minor tweaks here and there. The salient features are: 1. This is being developed as a pure PYTHON software. 2. None of the operations depend on IRAF tasks. We reiterate here that the aim is not to discourage IRAF and/or related pacakges, but with time since the packages have become unsupported and PYTHON packages have developed enough to perform all related tasks. For image display and related purposes, we use the GINGA package instead of DS9. 3. To reduce the images we use CCDPROC alongwith our custom written tools. 4. The PYTHON package PHOTUTILS is being used for the aperture photometry. We built all our codes on Python 3.6+. The required packages are: (It is recommended to install packages though pip and keep them to the latest versions. We execute the code mostly through Google Colab, so the latest versiosn of these packages are automatically picked. ) 1. Numpy 2. Astropy and its affiliated packages: (astropy 4.0 and above) 3. Photutils (photutils 0.6 and above) 4. CCDProc 5. Astroalign 6. astroquery 7. Matplotlib 8. Ginga We aim it to develop it as a fast and easy to handle alternative to the users dependent on IRAF/DAOPHOT kind of software. Currently, the work is slow on this as I have been busy with other projects. I hope to pick it up soon.