相关论文: 4C02.27: a quasar with episodic activity?

One of the striking examples of episodic activity in active galactic nuclei are the double-double radio galaxies (DDRGs) with two pairs of oppositely-directed radio lobes from two different cycles of activity. We illustrate, using the DDRG…

In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range of linear sizes (220 $-$ 917 kpc), and hence time scales of…

Recently Jamrozy et al. (2009) identified 4C 02.27 (J0935+0204) as the first possible example of a double-double radio source which is optically identified with a quasar (i.e. not a galaxy), at the redshift of z=0.649. The overall projected…

We present four Mpc-sized radio galaxies which consist of a pair of double-lobed radio sources, aligned along the same axis, and with a coinciding radio core. We have called these peculiar radio sources `double-double' radio galaxies (DDRG)…

We report a new double-double radio quasar, DDRQ, J0746$+$4526 which exhibits two cycles of episodic activity. From radio continuum observations at 607 MHz using the GMRT and 1400 MHz from the FIRST survey we confirm its episodic nature. We…

We present radio continuum observations at frequencies ranging from $\sim$150 to 5000 MHz of the misaligned double-double radio galaxy, DDRG, 3C293 (J1352+3126) using the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array…

We report the discovery of a double-double radio galaxy (DDRG), J0041+3224, with the Giant Metrewave Radio Telescope (GMRT) and subsequent high-frequency observations with the Very Large Array (VLA). The inner and outer doubles are aligned…

We present a multi-frequency analysis of the candidate double-double radio galaxy (DDRG) J2349-0003, exhibiting a possible lobe misalignment. High-resolution uGMRT observations at Bands 3 and 4 reveal a complex radio morphology featuring a…

There is increasing evidence to suggest that AGN activity may be episodic, with a wide range of possible time scales. Radio galaxies exhibit the most striking examples of episodic activity, with two or three distinct pairs of lobes on…

There has been a growing body of evidence to suggest that AGN activity, which is powered by mass accretion on to a supermasive black hole, could be episodic, although the range of time scales involved needs to be explored further. The…

Double-double radio galaxies (DDRGs) offer a unique opportunity for us to study multiple episodes of jet activity in large-scale radio sources. We use radio data from the Very Large Array and the literature to model two DDRGs, B1450+333 and…

The radio-emitting quasar SDSS J1425+3231 (z=0.478) was recently found to have double-peaked narrow [O III] optical emission lines. Based on the analysis of the optical spectrum, Peng et al. (2011) suggested that this object harbours a dual…

The radio structures and optical identifications of a sample of 242 sources classified as double-double radio sources by Proctor (2011) from a morphological study of sources in the FIRST (Faint Images of the Radio Sky at Twenty centimeters)…

We report the discovery of a double-double radio source (DDRS) J0028+0035. We observed it with LOFAR, GMRT, and the VLA. By combining our observational data with those from the literature, we gathered an appreciable set of radio flux…

To test the hypothesis that megaparsec-scale giant radio galaxies (GRGs) experience multiple epochs of recurrent activity leading to their giant sizes and to understand the nature of double-double radio galaxies (DDRGs), we have built the…

We present multifrequency radio observations of two well known episodic FR\,II radio galaxies (J0116$-$4722 and J1158+2621) and a detailed investigation of the life-cycle of episodic radio galaxies from their spectral and radiative…

Triple-double radio galaxies (TDRGs) are amongst the rarest subpopulations of radio galaxies (RGs). They are characterised by three pairs of radio lobes, where each pair of lobes represents an episode of nuclear activity. Such a feature…

The existence of double-double radio galaxies (DDRGs) is evidence for recurrent jet activity in AGN, as expected from standard accretion models. A detailed study of these rare sources provides new perspectives for investigating the AGN duty…

We report the discovery of a `Triple-Double Radio Galaxy (TDRG)' J1216+0709 detected in deep low-frequency Giant Metrewave Radio Telescope (GMRT) observations. J1216+0709 is only the third radio galaxy, after B0925+420 and Speca, with three…

The excellent sensitivity and optimum resolution of LoTSS DR2 at 144 MHz has enabled us to discover a giant radio galaxy (J1225+4011) with three distinct episodes of jet activity, making it a member of a class of objects called…