• P. Kharb

      Articles written in Journal of Astrophysics and Astronomy

    • From Nearby Low Luminosity AGN to High Redshift Radio Galaxies: Science Interests with Square Kilometre Array

      P. Kharb D. V. Lal V. Singh J. Bagchi C. H. Ishwara Chandra A. Hota C. Konar Y. Wadadekar P. Shastri M. Das K. Baliyan B. B. Nath M. Pandey-Pommier

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      We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active galactic nuclei in the nearby Universe to powerful radio galaxies at high redshifts. Important unresolved science questions in AGN physics are discussed. Ongoing low-frequency surveys with the SKA pathfinder telescope GMRT, are highlighted.

    • Searching for dual active galactic nuclei


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      Binary or dual active galactic nuclei (DAGN) are expected from galaxy formation theories. However, confirmed DAGN are rare and finding these systems has proved to be challenging. Recent systematic searches for DAGN using double-peaked emission lines have yielded several new detections, as have the studiesof samples of merging galaxies. In this paper, we present an updated list of DAGN compiled from published data. We also present preliminary results from our ongoing Expanded Very Large Array (EVLA) radio study of eight double-peaked emission-line AGN (DPAGN). One of the sample galaxy shows an S-shaped radio jet. Using new and archival data, we have successfully fitted a precessing jet model to this radio source. We find that the jet precession could be due to a binary AGN with a super-massive black-hole (SMBH) separation of $\sim$0.02 pc or a single AGN with a tilted accretion disk. We have found that another sample galaxy, which is undergoing a merger, has two radio cores with a projected separation of 5.6 kpc. We discuss the preliminaryresults from our radio study.

    • A polarization study of three blazars using uGMRT at $\sim$600 MHz


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      We present results from our radio polarimetric study with the upgraded giant metrewave radio telescope (uGMRT) at band 4 (550–850 MHz) of three blazars: radio-loud quasars 3C390.3, 4C71.07 and BL Lac object 1ES 2344$+$514. The aim of this study was (i) to carry out a feasibility study for band 4 polarization with the uGMRT and (ii) to compare and contrast the kpc-scale polarization properties between the blazarsub-classes. We have detected linear polarization in all the three sources. The degree of linear polarization in the cores of the two quasars is higher than the BL Lac object, consistent with similar differences observed on parsec-scales in blazars. The highest fractional polarization of $\approx$15% is observed in the hotspot region of3C390.3, which also shows extended polarized lobe structures. 1ES 2344$+$514 shows a core–halo structure, whereas 4C71.07 remains unresolved. A rotation of polarization electric vectors along the northern hotspot of 3C390.3 and the core of 1ES 2344$+$514, suggest jet bending. Greater depolarization in the southern lobe of 3C390.3 compared to the northern lobe indicates the presence of Laing–Garrington effect. Multi-frequency uGMRT polarimetric data are underway to study the kpc-scale rotation measures across these sources to find differences in the surrounding media.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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