Dr. Darshan Kakkad

I am a post-doctoral research fellow at the European Southern Observatory with functional duties at the Very Large Telescope in Cerro Paranal Observatory in Chile. I am MUSE instrument fellow and support the operations of the Unit Telescope 4. Prior to my job in Chile, I was a PhD student at the European Southern Observatory headquarters in Garching near Munich in Germany for three years. I did my masters degree in Physics from Indian Institute of Technology-Madras in Chennai and a bachelors in Physics from the University of Delhi in India.

My primary research interest is the study of AGN feedback for low as well as high redshift galaxies. A short summary of my published papers is described below.

ISM conditions in low-z AGN hosts: Electron density

Kakkad et al. 2018, Spatially resolved electron density in the narrow line region of z < 0.02 radio AGNs: One of the main challenges in AGN feedback studies is the large uncertainties associated with the determination of mass outflow rates and outflow kinetic power of the ionized gas. Except for a few exceptional targets, it is therefore not possible to know whether the observed winds are driven by the AGN or by star formation processes and whether the outflowing gas is capable of escaping the host galaxy. In this paper, we determine the electron density in low redshift radio AGNs in both outflowing and non-outflowing medium using [SII]6716, 6731 doublet. We find that for a majority of non-outflowing targets, the electron density is higher in the sites of star formation. In the presence of an outflow, the spatial correlation of density with star forming sites ceases to exist. The electron density in an outflowing medium shows a much wider range in its values compared to the non-outflowing targets. We used optical IFU data from WiFeS/ANU for this project.

Molecular gas in AGN hosts at high redshift

Kakkad et al. 2017, ALMA observations of cold molecular gas in AGN hosts at z~1.5 - Evidence of AGN feedback?: A question often posed is whether AGNs are special or are they only a phase in the life-cycle of galaxies? In this paper, we used ALMA observations of high redshift X-ray selected AGN host galaxies to determine their molecular gas content and compare the results with those of inactive galaxies at similar redshift, matched in stellar mass and star formation rate. Determining the fate of molecular gas in high redshift galaxies is crucial to our understanding of galaxy evolution, as it is out of this gas that ultimately stars are formed. CO(2-1) transition was used as the molecular gas tracer, which is observable in ALMA Band-3. AGN selection in the X-rays have the advantage that it is free from contamination by other sources within the host galaxy (X-ray cut of > 42 erg/s). Our results suggest that the molecular gas fraction of the selected AGN host galaxies are a factor of ~2 less than non-AGN control galaxies. This can be either due to positive or negative feedback from AGNs. Further details and discussion is given in the paper.

Ionized gas outflows

Kakkad et al. 2016, Tracing outflows in the AGN forbidden region with SINFONI: In this paper, we pre-selected a sample of high redshift X-ray selected AGN host galaxies which have a high probability of hosting outflows based on an impirical curve derived in Fabian et al. 2008. The aim was to characterize these outflows using near-infrared IFU spectroscopy. Using a careful PSF analysis, we found that the outflows are extended to kiloparsec scales in the host galaxies of these AGNs. Moreover, this paper does an extensive overview of the underlying systematic uncertainties in the determination of mass outflow rates.

PSF characterization of AO-assisted observations

As a part of my functional work at Paranal, I am involved in projects to characterize the Point Spread Function (PSF) of the Wide Field Mode (WFM) and Narrow Field Mode (NFM) observations with MUSE.

Currently, I am an active member of the SUPER survey, BASS survey and the S7 survey.

Click here to download a pdf version of my CV.

You can find a list of my publications here

Office M.212 European Southern Observatory
Alonso de Cordova, 3107, Vitacura
Casilla 19001, Santiago, Chile
Email: dkakkad@eso.org