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Exploring the formation and evolution of galaxies, focusing on understanding their stellar populations and structural properties. My current research involves studying polar ring galaxies to investigate their role in connecting early- and late-type galaxies.
PhD: My thesis investigates how Polar Ring Galaxies (PRGs) bridge the evolutionary gap between early- and late-type galaxies. This study identifies distinct evolutionary stages and unique structural features of PRGs, suggesting their potential transition toward elliptical forms. Observational data and cosmological simulations support these findings, providing valuable insights into the processes driving galaxy evolution. Thesis Title: Tracing the Evolution of Polar Ring Galaxies Through Multi-Wavelength Observations and Cosmological Simulations
Supervisor: Dr. Sreeja S. Kartha, Institute: Centre for Excellence in Astronomy and Astrophysics, Christ University, Bangalore, India
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Masters: During my master's, I studied early-type galaxies in nearby galaxy clusters, focusing on their UV upturn phenomenon. We identified UV upturn galaxies in the Virgo cluster and studied their spectral energy distributions. Thesis Title: Study of UV Upturn in Early-Type Galaxies
Supervisor: Dr. Sreeja S. Kartha, Institute: Centre for Excellence in Astronomy and Astrophysics, Christ University, Bangalore, India
Publications list in NASA ADS:
Polar Ring Galaxies
Polar Ring Galaxies
A polar ring galaxy is a rare system characterized by a ring of stars, gas, and dust orbiting nearly perpendicular to the plane of the host galaxy, typically elliptical or lenticular. These structures are thought to form through accretion or mergers and provide unique insights into galaxy dynamics, including dark matter distribution and evolutionary processes.
Image: The best example of a Polar Ring Galaxy, NGC 4650a, is shown with a colour composite using HST WFPC2 images. The F814, F606, and F450 filters are mapped to red, green, and blue, respectively. On the right is the grayscale image of the F606 filter.
See this interesting paper: akhil et al. (2024)
Globular cluster systems in galaxies
Globular cluster systems in galaxies
Globular Cluster Systems in Galaxies are collections of dense, spherical star clusters that orbit a galaxy's halo. These clusters, among the oldest stellar populations, provide insights into a galaxy's formation history, chemical evolution, and dark matter distribution. Their spatial distribution and properties vary with galaxy type, reflecting the host galaxy's evolutionary processes.
Image: The GCS of the Milky Way (left) and the centre of the Virgo cluster, represented by M87 (right), are shown here. The Milky Way globular clusters are obtained from Harris et al. 1996. The Sun is marked with a star symbol within the disk of the Milky Way. The globular cluster data for the central region of the Virgo Cluster is obtained from the NGVS survey
Globular cluster systems in PRGs
Globular cluster systems in PRGs
We utilize wide and deep-field observations of the CFHT as part of the NGVS to investigate the GCS of NGC4262. We presented the first optical image of NGC4262 with an optically faint ring component.
See this paper: Akhil et al. (2024b)
Image: Cluster-forming clouds are marked by red dots on a Milky Way map. Left panel: Antennae and Triangulum Galaxy. The inset shows the Eagle Nebula and [DBS2003]179, featuring the young star clusters.
Image credit: Nagoya University, National Astronomical Observatory of Japan, NASA, JPL-Caltech, R. Hurt (SSC/Caltech), Robert Gendler, Subaru Telescope, ESA, Hubble Heritage Team (STScI/AURA), Hubble Collaboration, and 2MASS
Star formation in galaxies
Star formation in galaxies
Star Formation in Galaxies refers to the process by which dense regions within molecular clouds collapse under gravity to form new stars. This activity is influenced by factors such as gas density, turbulence, and feedback from existing stars. Star formation drives galaxy evolution, shaping their structure and contributing to their luminosity, chemical enrichment, and energy output.
Evolutionary pathway of PRGs
We investigate distinct features of PRGs (ring and host components), elucidate their unique characteristics through Spectral Energy Distribution (SED) fitting, and examine star formation rates and stellar populations. Also, we analyze resolved-scale star-forming regions using Astrosat UVIT observations.
See this paper: Akhil et al. 2025
Interaction in galaxies
Interaction in galaxies
Interactions in Galaxies refer to gravitational encounters between galaxies that can lead to tidal distortions, mergers, and the redistribution of stars, gas, and dark matter. Such interactions trigger phenomena like starbursts, active galactic nuclei, and morphological transformations, playing a pivotal role in galaxy evolution and the formation of larger structures.
Image: DECaLS optical images of NGC 3808 and SPRC 76
See this works: Robin et al. (2024)
Insights from Simulations
Insights from Simulations
I have extensive experience working with post-processed data from cosmological simulations like TNG50, focusing on the interactions and evolution of galaxies. My research involves investigating the formation and dynamics of unique systems such as PRGs to understand their role in galaxy evolution and their connection to galaxy interactions.
Early type galaxies and UV upturn
Early type galaxies and UV upturn
Early-Type Galaxies and the UV Upturn: Early-type galaxies (ellipticals and lenticulars) are traditionally dominated by older, red stars, yet some exhibit unexpected ultraviolet (UV) excess, known as the UV upturn. This phenomenon is attributed to hot, low-mass stars, such as extreme horizontal branch stars or their progeny, formed through enhanced helium abundance or binary evolution. The UV upturn provides key insights into stellar population dynamics and the chemical evolution of these galaxies.
Image: An illustration of UV upturn feature in the SED of galaxy VCC 1632, built using CIGALE.
See this paper: Akhil et al. (2024c)
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