A Multi-wavelength Investigation of Blazar Jets

The National Centre for Radio Astrophysics, Tata Institute of Fundamental Research (NCRA-TIFR), Pune, India, is seeking a Post-Doctoral Fellow to work on “A Multi-wavelength Investigation of Blazar Jets”, with Professor Preeti Kharb and collaborators. This project aims to conduct a focused investigation of jets in the luminous AGN subclass of BL Lac objects, through high-sensitivity, multi-frequency polarimetric observations using the GMRT. These observations will trace kpc-scale magnetic field structures and the magneto-ionic environments around BL Lac jets, enabling insights into their dynamics and jet-medium interactions. The radio data will be complemented by multi-wavelength data from gamma-rays, X-rays, optical, and infrared observations to construct and analyse their spectral energy distributions (SEDs), in particular in the high synchrotron peaked (HSP), and low-synchrotron peaked (LSP) BL Lacs.

Previous uGMRT studies of the Palomar Green (PG) BL Lac sample have revealed that several LSP BL Lacs show morphological and polarimetric features typically associated with radio-loud Quasars including terminal hotspots and poloidal magnetic field structures on kpc-scales. These observations support the “blazar envelope scenario”, which posits two intrinsically distinct jet populations: one comprising high-power, fast jets associated with Quasars and LSP BL Lacs, and another of slower, lower-power jets observed in the HSP BL Lacs. This project will start by looking at the existing PG sample data and extend the analysis to additional well-studied BL Lacs to test the generality of these findings and evaluate whether such structural and polarimetric traits consistently map onto their SED peak classifications. Additionally, it will aim to determine the jet characteristics that set LSP BL Lacs and quasars apart. By examining the multi-frequency polarisation and its correlation with SED properties, this study will place constraints on the jet magnetic field geometry and emission mechanisms. It will also explore how jet power, orientation, and environmental conditions contribute to the differentiation of AGN sub-classes.

Prior experience in the areas of radio interferometric observations and data analysis is a positive but is not essential for the project. The post-doctoral fellow will be encouraged to acquire additional multi-wavelength data including with the GMRT to expand on the scientific scope of this project.

Research activities at NCRA-TIFR are centered on low-frequency radio astronomy, with faculty members pursuing research in diverse areas of astrophysics. NCRA-TIFR operates two large observational facilities, the Giant Metrewave Radio Telescope and the Ooty Radio Telescope.

Applications containing a curriculum vitae, a research plan, and the names and e-mail addresses of three or more referees should be sent to the Dean, NCRA-TIFR Faculty, at the e-mail address dean_nf@ncra.tifr.res.in, by May 31, 2025. Applicants should also request their referees to send in recommendation letters by the same deadline. All enquiries should also be made to this e-mail address. All applicants will automatically be considered for all available Post-Doctoral Fellowships at NCRA-TIFR.

The monthly salary of Post-Doctoral Fellows at NCRA-TIFR depends on experience after the doctoral degree. Candidates are required to have at least a provisional Ph.D. degree when taking up the position. For candidates who have received their doctoral degrees, the monthly salary ranges from INR 58,000 to INR 67,000. Post-doctoral fellows are also entitled to a contingency grant of INR 40,000 per year. All project post-doctoral positions are tenable for a maximum of 3 years, with continuations subject to a yearly review.

Post-doctoral Fellows at NCRA-TIFR are provided a travel grant of INR 3,00,000 over the course of the fellowship to enable them to travel for international conferences or for research collaborations. They are also entitled to a house rent allowance, and medical coverage under NCRA-TIFR's medical scheme.