The Origin of Radio Outflows in Low Luminosity Active Galactic Nuclei

Post-Doctoral Fellowships

The National Centre for Radio Astrophysics, Tata Institute of Fundamental Research (NCRA-TIFR), Pune, India, is seeking a Post-Doctoral Fellow to work on the origin of radio outflows in low-luminosity active galactic nuclei (AGNs), with Dr. Preeti Kharb.

The origin of radio outflows in low-luminosity active galactic nuclei (LLAGNs) is unclear. While a large fraction of LLAGNs that comprise Seyfert and LINER galaxies are classified as "radio-quiet", sensitive radio observations have revealed the presence of kilo-parsec-scale radio structures (KSRs) in many (>40 percent) of them, in complete samples. However, whether it is an AGN jet, an accretion-disk wind or a starburst super-wind that powers the KSR is a matter of considerable debate in the literature. Only after the AGN jet contribution can be properly accounted for in LLAGNs, can one attempt to understand why these sources do not produce the impressive large-scale jets that one observes in powerful AGNs like Cygnus A. Are the LLAGN jets low-powered and therefore easily snuffed out by the galactic ISM? Or do the LLAGN jets lose collimation soon after ejection and flare up into radio lobes or KSRs? Spectral index imaging is a powerful method by which the non-thermal AGN emission could be separated from thermal emission from stellar winds, although there would also be contributions to non-thermal emission from the latter. Another powerful method to check the origin of the radio outflows in LLAGN is to trace the radio emission from parsec-scales, just as they are ejected by the AGN or launched from a nuclear starburst and follow them on to kilo-parsec-scales. The project will follow this two-pronged approach to understand the outflows in LLAGNs. Low-frequency GMRT data at 325 MHz have been acquired and reduced for nearly 30 LLAGN with KSRs, that have the CfA and Extended 12 micron surveys as their parent samples. GHz-frequency data from the Very Large Array (VLA) exist for this sample. A good fraction of these LLAGN have parsec-scale imaging data via Very Long Baseline Interferometry (VLBI).

The post-doctoral fellow is expected to create a comprehensive picture of the outflows in this LLAGN sample using a multi-wavelength, multi-scale approach. Candidates are expected to be familiar with radio data analysis and AGN astrophysics. They are expected to supplement existing data with new GMRT, VLA, and VLBI data by writing proposals, and expanding the scope of the project. Polarimetric GMRT data in particular would be acquired in order to attack the problem of the origin of LLAGN outflows from a third front, on the assumption that AGN outflows would be more highly polarized than stellar ones.

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 deanncra@ncra.tifr.res.in, by October 31, 2018. 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.

When taking up the position, candidates must have a Ph.D. in physics, astronomy, or a related subject, or must be awaiting the award of the Ph.D. degree after submitting the doctoral thesis to a university.

The monthly salary of Post-Doctoral Fellows at NCRA-TIFR depend on experience after the doctoral degree. The monthly salary of candidates who join after submitting their doctoral thesis, but without receiving their doctoral degree, is INR 32,000. For candidates who have received their doctoral degrees, the monthly salary ranges from INR 36,000 to INR 40,000. Post-doctoral fellows are also entitled to a contingency grant of INR 32,000 per year. All 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.

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