Souradeep Bhattacharya
DST-INSPIRE Faculty at Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, India
About Me
I am a DST-INSPIRE Faculty Fellow at IUCAA. My primary research interest is in understanding the recent formation history of nearby galaxies using Planetary Nebulae as chemodynamical tracers. I also work extensively on Galactic open cluster structure and dynamics. I have also recently forayed into studying higher redshift star-forming galaxies primarily with ASTROSAT/UVIT.
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I originally hail from Agartala, Tripura, India. From 2012 to 2017, I pursued a double major in Physics (Integrated M.Sc.) and Electrical and Electronics Engineering (B.E.), at the Birla Institute of Technology and Science, Pilani, India. I carried out my PhD (2017-2020) at the European Southern Observatory (ESO) through the IMPRS on Astrophysics at LMU Munich, supervised by Dr. Magda Arnaboldi (ESO) and Prof. Dr. Ortwin Gerhard (MPE/LMU). I then returned to IUCAA in 2020 first as a regular post-doctoral fellow and now as a DST-INSPIRE Faculty Fellow.
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Please have a look at my CV for more details.
The survey of Planetary Nebulae in Andromeda (M31): IV. Radial oxygen and argon abundance gradients of the thin and thicker disc, 2022, MNRAS, 517, 2343
Souradeep Bhattacharya, Magda Arnaboldi, Nelson Caldwell, Ortwin Gerhard, Chiaki Kobayashi, Johanna Hartke, Alan McConnachie, Kenneth C. Freeman and Puragra Guhathakurta
A Gaia EDR3 search for tidal tails in disintegrating open clusters, 2022, MNRAS, 517, 3525
Souradeep Bhattacharya, Khushboo K. Rao, Manan Agarwal, Shanmugha Balan and Kaushar Vaidya
The survey of Planetary Nebulae in Andromeda (M31): III. Constraints from deep planetary nebula luminosity functions on the origin of the inner halo substructures in M 31, 2021, A&A, 647, A130
Souradeep Bhattacharya, Magda Arnaboldi, Ortwin Gerhard, Alan McConnachie, Nelson Caldwell, Johanna Hartke and Kenneth C. Freeman
My Research
My primary research interest is in understanding the recent formation history of nearby galaxies using Planetary Nebulae as chemodynamical tracers. To this end, I have mainly worked on the recent formation history of Andromeda (M31). The close distance of M31 allows us to probe the chemodynamics of its structural components and unravel its formation history, especially its major merger thought to have happened 2-3 Gyr ago. It also allows us to study the relation of PNe with their parent stellar population, in the context of stellar evolution.
I also work extensively on Galactic open cluster structure and dynamics, with my most recent work on tidal tails in open clusters. I have also recently forayed into studying higher redshift star-forming galaxies primarily with ASTROSAT/UVIT.
I have also previously worked on studying X-ray sources in the globular cluster 47 Tuc.
Survey of Planetary Nebulae in Andromeda (M31) - Imaging the disc and inner halo
For my PhD, I am carrying out a survey of Planetary Nebulae (PNe) in the disk and inner halo (~60 sq. deg.) of M31. This is the largest sample of PNe in any galaxy. We identify them as point-like sources by comparing [OIII] (narrow-band) and g (broad-band) images from the MegaCam imager at the 3.6m CFHT. For the PNe identified within the inner 16 sq. deg. (Bhattacharya et al. 2019b), we observe a rise in the faint-end of the PN luminosity function in M31 at all radial distances, possibly related with the star-formation history of M31.
Survey of Planetary Nebulae in Andromeda (M31) II-Â Disk Kinematics
Spectroscopic follow-up of some of the PNe identified in the imaging survey was carried out with the HectoSpec multi-fibre spectrograph at the 6.5m MMT. The PNe are divided into high and low extinction samples, whose kinematics are fitted to obtain the rotation curves and rotational velocity dispersion profiles of the M31 disc. We obtain the age-velocity dispersion relation in different deprojected elliptical bins (Bhattacharya et. al 2019c, A&A, in submission).
Studies of open clusters
For my Masters thesis at IANCU with Dr. Wen-Ping Chen, I confirmed the core-tail shape of the oldest known open cluster Berkeley 17 with Pan-STARRS data, also finding that it exhibits mass segregation. We found that nearly half its expected Blue Straggler candidates (BSSs) could be field contaminants (Bhattacharya et al. 2017b). Recently with Gaia DR2, we confirm the number of BSSs and find that they show a bimodal radial distribution, similar to globular clusters of intermediate dynamical age undergoing dynamical relaxation. (Bhattacharya et al. 2019a).
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I also presented the maiden use of the DBSCAN algorithm to determine open cluster morphology for two Galactic open clusters, Czernik 20 and NGC 1857, from spatial distribution of near infrared (NIR) data from the UKIDSS and 2MASS surveys (Bhattacharya et al. 2017a).
Catalogue of X-ray sources in the globular cluster 47 Tuc
As a summer intern at the University of Alberta with Dr. Craig Heinke, I combined Chandra ACIS observations of the globular cluster 47 Tuc to create a deeper X-ray source list, and study some of its faint radio millisecond pulsars (MSPs). We are able to extract X-ray spectra of MSPs 47 Tuc aa, ab, Z, S and F. We limit X-ray emission from the full surface of the rapidly spinning MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar constraining the shape of the r-mode instability window (Bhattacharya et al. 2017c).