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Publications (23)
Understanding the origins of massive black hole seeds and their coevolution with their host galaxy requires studying intermediate-mass black holes (IMBHs) and estimating their mass. However, measuring the masses of these IMBHs is challenging, due to the high-spatial-resolution requirement. Spectrophotometric reverberation monitoring is performed fo...
We present near-simultaneous X-ray and optical polarization measurements in the high synchrotron peaked (HSP) blazar Mrk 421. The X-ray polarimetric observations were carried out using Imaging X-ray Polarimetry Explorer (IXPE) on 2023 December 6. During IXPE observations, we also carried out optical polarimetric observations using 104 cm Sampurnana...
Blazars, the peculiar class of active galactic nuclei, are known to show flux variations across the accessible electromagnetic spectrum. Though they have been studied extensively for their flux variability characteristics across wavelengths, information on their ultraviolet (UV) flux variations on timescales of hours is very limited. Here, we prese...
Understanding the origins of massive black hole seeds and their co-evolution with their host galaxy requires studying intermediate-mass black holes (IMBHs) and estimating their mass. However, measuring the mass of these IMBHs is challenging due to the high spatial resolution requirement. A spectrophotometric reverberation monitoring is performed fo...
We present near-simultaneous X-ray and optical polarization measurements in the high synchrotron peaked (HSP) blazar Mrk 421. The X-ray polarimetric observations were carried out using {\it Imaging X-ray Polarimetry Explorer} ({\it IXPE}) on 06 December 2023. During {\it IXPE} observations, we also carried out optical polarimetric observations usin...
Blazars, the peculiar class of active galactic nuclei (AGN), are known to show flux variations across the accessible electromagnetic spectrum. Though they have been studied extensively for their flux variability characteristics across wavelengths, information on their ultraviolet (UV) flux variations on time scales of hours is very limited. Here, w...
We investigate the torus size–luminosity relation of Type 1 active galactic nuclei (AGNs) based on the reverberation-mapping analysis using the light curves of the optical continuum and the IR continuum obtained with the W1 and W2 bands of the Wide-field Infrared Survey Explorer survey. The final sample consists of 446 and 416 AGNs, respectively, f...
The correlation between optical and γ-ray flux variations in blazars reveals a complex behaviour. In this study, we present our analysis of the connection between changes in optical and γ-ray emissions in the blazar Ton 599 over a span of approximately 15 years, from August 2008 to March 2023. Ton 599 reached its highest flux state across the entir...
We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from July to December, 2018 using broad-band B, R and narrow band Hα and S II filters. B-band traces the continuum emission from the accretion disk, R-band encompasses both the...
We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from July to December, 2018 using broad band B, R and narrow band H{\alpha} and S II filters. B-band traces the continuum emission from the accretion disk, R-band encompasses b...
Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation mapping (RM) has provided estimates of BLR size for more than 100 AGN now, however, the structure of the BLR has been studied for o...
Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation mapping (RM) has provided estimates of BLR size for more than 100 AGN now, however, the structure of the BLR has been studied for o...
We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229−15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to 2018 December in B, V, J, H and Ks bands. The calculated spectral index (α) between B and V bands for each epoch was used to correc...
We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229-15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to 2018 December in B, V, J, H and Ks bands. The calculated spectral index ({\alpha}) between B and V bands for each epoch was used to...
Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax.
The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will survey the sky that covers a width of about 27\(^\prime \). To carry out astrometric calibration of the ILMT observations, we aimed...
Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will survey the sky that covers a width of about 27 arcminute. To carry out astrometric calibration of the ILMT observations, we aimed t...
Blazars show optical and γ-ray flux variations that are generally correlated, although there are exceptions. Here we present anomalous behaviour seen in the blazar 3C 454.3 based on an analysis of quasi-simultaneous data at optical, ultraviolet, X-ray, and γ-ray energies, spanning about 9 yr from 2008 August to 2017 February. We have identified fou...
Active galactic nuclei (AGN) are high luminosity sources powered by accretion of matter onto SMBHs located at the centres of galaxies. The SMBH is surrounded by a broad emission line region (BLR) and a dusty torus. It is difficult to study the extent of the dusty torus as the central region of AGN is not resolvable using any conventional imaging te...
Blazars show optical and $\gamma$-ray flux variations that are generally correlated, although there are exceptions. Here we present anomalous behaviour seen in the blazar 3C 454.3 based on an analysis of quasi-simultaneous data at optical, UV, X-ray and $\gamma$-ray energies, spanning about 9 years from August 2008 to February 2017. We have identif...
Active galactic nuclei (AGN) are high luminosity sources powered by accretion of matter onto super-massive black holes (SMBHs) located at the centres of galaxies. According to the Unification model of AGN, the SMBH is surrounded by a broad emission line region (BLR) and a dusty torus. It is difficult to study the extent of the dusty torus as the ce...
The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGN). Here, we present the first measurements of the time delay between optical and near-infrared (NIR) flux variations in H0507+164, a nearby Seyfert 1.5 galaxy at z = 0.018. The observations in the optical V -band...
The detection of significant $\gamma$-ray emission from radio-loud narrow line Seyfert 1 (NLSy1s) galaxies enables us to study jets in environments different than those in blazars. However, due to the small number of known $\gamma$-ray emitting NLSy1 ($\gamma$-NLSy1) galaxies, a comprehensive study could not be performed. Here we report the first d...
