Research Projects
Radio Observation of Post-Starburst Galaxies
My ongoing Thesis work focuses on studying the E+A or Post-Starburst galaxies mainly from LOFAR Radio Data. These galaxies show emission lines similar to A type stars in optical spectra; only about 1% of ellipticals in local universe show this special kind of signature. Stellar population synthesis studies estimate the PSB galaxies experienced a starburst in the recent (a few hundred Myr) past.SFR in recent burst ranged from 50 -300 M☉/year, ~10-80% of the total stellar mass was formed during the recent burst and presently these galaxies have very little to no star-formation. The exact mechanism for the quick quenching is still under debate. Internal processes like feedback from active galactic nuclei (AGN) or explosions of massive stars during a star-burst phase (Supernovae Feedback) can play vital role in expelling gas reservoir or ionizing the star-forming gas - as a result star formation get quenched. Recent millimetre wavelength observations using ALMA show that galaxies contain significant amount of molecular gas - suggest star forming gas may be present in Post Starbursts but inefficient to form stars. We need to investigate how internal processes can quickly shut down star formation. As the Post Starbursts have radio flux density in ~mJy level large number of Post Starbursts could not be studied with previous NVSS, VLA-FIRST, TGSS data - recent LOFAR catalog with μJy rms sensitivity give us opportunity to study large number of Post Starbursts in radio . I am using a combination of multi-wavelength observations with both ground based and space based facility (LOFAR 144MHz ,VLA 1.4 MHz-radio; SDSS-optical; IRAS 12-100 µm, Splitzer 3.6-8µm, WISE-Infrared 3.4-22 µm; GALEX-Ultraviolet 135-280 nm) to understand the physical processes (Environment effect,AGN/Stellar Feedback,Merging Phenomena) driving the star formation quenching event.
Using continum image data of deep extragalactic field from the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) at 120-168 MHz and applying existing photometric and spectroscopic techniques we have made a catalogue of nearby (redshift z<0.4) radio-Post Starburst galaxies which have radio emission of several mJy flux. We want to investigate the star-formation histories, morphologies, dust content, environment and AGN activity for our sample by carrying out new observation as well as analyzing archival data.
Study of ELG, LINER, QUASAR spectra from SDSS archival
data for building a ML based classification model
I am working on a collaborative project to build a ML based classification model by training optical spectrum of low redshift galaxies to classify them into Emission Line Galaxy, Low Ionisation Nuclear Line Region and Quasar. Each type of galaxies have district emission /absorbsion line feature i.e ELG have narrow spectral lines,Quasar have both narrow and broad spectral lines etc. We are trying different ML classification methods and testing the accuracy of them.