Akanksha Kapahtia
Post-Doctoral Fellow
Email: akapahtia [at] ncra.tifr.res.in
Phone: 020-2571 9218
Extn: 9218
Office: 218A
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA
Main Research Areas: Cosmology; The Epoch of Reionization; HI 21cm cosmology; Large-scale structure of the universe; Topological data analysis
Biography:
Akanksha completed her B.Sc. in Physics and Electronics from the Department of Physics, Panjab University, Chandigarh, in 2011, and her M.Sc. in Physics from the Department of Physics and Astrophysics, University of Delhi, in 2013. She joined the Joint Astronomy Programme of Indian Institute of Science, Bengaluru, for a Ph.D. in 2014, working with Pravabati Chingangbam of the Indian Institute of Astrophysics on real-space statistical tools for 21cm cosmology. She obtained her Ph.D. degree in November, 2020, and then moved to NCRA-TIFR in December 2020 as a post-doctoral fellow.Research description:
The evolution of the intergalactic medium (IGM) post cosmic dawn is marked by two major epochs due to hydrogen reionization (which ended by z~5.5) followed by the epoch of Helium reionization (which ended at z~3). Hydrogen was reionized by high-energy photons emitted by the first generation of galaxies in the universe. A direct probe of the epoch of hydrogen reionization (the EoR) is the spin-flip 21cm transition of the neutral hydrogen atom. The power spectrum of the 21cm brightness temperature will be measurable with upcoming radio interferometers such as the Square Kilometre Array (SKA). The SKA would also have imaging capabilities at this epoch. The highly non-Gaussian nature of this signal requires one to explore statistical techniques which go beyond the usual 2-point statistics-based power spectrum. During my PhD I studied the prospects of employing real-space morphological descriptors called Minkowski tensors and topological quantities called Betti numbers to infer the prospects of constraining global properties of luminous sources during the EoR.The epoch of Helium reionization refers to the epoch when singly ionized helium (HeII) became doubly ionized. Since the ionization energy of HeII is greater than that of neutral hydrogen and helium, HeII ionization requires highly energetic photons, mostly emitted by quasars. The process of HeII reionization leaves important imprints on the Ly-alpha forest and the thermal history of the IGM. Therefore, the epoch of helium reionization is observationally more accessible than the epoch of hydrogen reionization. This can allow one to obtain more stringent tests for the models of reionization which are consistent with observed IGM properties. I am currently working on developing efficient semi-numerical simulations to model the epoch of helium reionization consistent with observed quasar and IGM properties.
Selected publications:
1. Morphology of 21cm brightness temperature during the Epoch of Reioinization using Contour Minkowski Tensor, (Akanksha Kapahtia et al. 2019, JCAP, 9, 053) 2. A novel probe of ionized bubble shape and size statistics of the epoch of reionization using the contour Minkowski Tensor, (Akanksha Kapahtia et al. 2018, JCAP 10, 011)
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