Recurrent Jet Activity in GRG J1007+3540 Reveals 1.45 Mpc Extension

Giant radio galaxies provide a unique window into the complex interplay between active galactic nuclei (AGN), their host galaxies, and the surrounding environment. Researchers AdaShobha Kumari, Sabyasachi Pal, and Surajit Paul, from Midnapore City College and Manipal Academy of Higher Education, alongside Marek Jamrozy from the Obserwatorium Astronomiczne, Uniwersytet Jagielloński, present a detailed multiwavelength study of the giant radio galaxy J1007+3540, extending 1.45 Mpc and residing within a substantial galaxy cluster. Their findings reveal compelling evidence for recurrent jet activity and a detached, tail-like structure, suggesting an episodic duty cycle for the AGN. This research is significant because J1007+3540 exhibits a rare combination of features , a restarted jet, a detached tail, and unusual spectral flattening , offering an exceptional opportunity to investigate how AGN activity, star formation, and the cluster environment are interconnected in these colossal structures.

J1007+3540’s jet-cluster interaction revealed

Scientists have unveiled a multiwavelength study of the giant radio galaxy J1007+3540, revealing crucial insights into the evolution of radio jet morphology and its energetic interplay with the surrounding environment. The research, utilising data from the LOFAR Two-metre Sky Survey second data release (LoTSS DR2) at 144MHz and the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400MHz, demonstrates that giant radio galaxies, extending to scales of entire galaxy clusters and beyond, are ideal for investigating jet-intracluster medium interactions. J1007+3540 exhibits a projected linear extension of 1.45 Mpc and resides within the WHL 100706.4+354041 cluster, hosted by the galaxy MaxBCG J151.77665+35.67813. The team achieved a detailed analysis of the radio source, identifying clear signatures of recurrent jet activity, a one-sided, extended, tail-like structure exhibiting a distinct morphological break.
Radiative ages were estimated for the inner lobes and outer north lobe, revealing values of approximately 140 Myr and 240 Myr, respectively, providing a timeline for the jet’s evolution and energy dissipation. This work establishes a connection between the galaxy’s environment and the observed jet characteristics, suggesting that the intracluster medium significantly influences the source’s longevity and morphology. Furthermore, optical-to-infrared spectral energy distribution modelling was performed to characterise the host galaxy. Experiments show the host galaxy is an evolved elliptical system with a stellar mass of log10(M★/M⊙) = 11.0 and an old stellar population age of around 12 Gyr.

Surprisingly, the study reveals a high infrared-derived star formation rate of approximately 106 M⊙yr−1, indicating substantial dust-obscured star formation potentially driven by merger-induced gas inflows. This discovery is particularly noteworthy, as it suggests ongoing star formation within an otherwise quiescent elliptical galaxy, challenging conventional understanding of galaxy evolution in dense cluster environments. This research unveils a rare combination of features in J1007+3540: a restarted jet, a detached tail-like structure, and unusual spectral flattening beyond the tail break, a combination rarely observed in giant radio galaxies. The study proves that this remarkable system serves as a unique laboratory for probing the complex interplay between active galactic nucleus activity, star formation processes, and the environmental effects within galaxy cluster surroundings.

The0.2s integration time across four scans. The team calibrated the data using 013C 147 and 3C 286 as flux calibrators, observed for 5 and 4 minutes respectively, and 0.1021+219 as a phase calibrator, observed four times for five minutes per scan. Researchers activated the uGMRT RFI filter0.20 × 6.23” at 400MHz and 6 × 6” at 144MHz. Furthermore, the team constructed an optical-to-infrared spectral energy distribution (SED) to investigate the host galaxy’s physical properties and central active galactic nucleus (AGN), providing a comprehensive understanding of this unique GRG.

J1007+3540’s Mpc-Scale Jet and Cluster Environment

Scientists have unveiled detailed multiwavelength observations of the giant radio galaxy (GRG) J1007+3540, revealing crucial insights into its morphology and energetic processes. The research, utilising data from the LOFAR Two-metre Sky Survey second data release (LoTSS DR2) at 144MHz and the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400MHz, demonstrates a projected linear extension of 1.45 Mpc for this remarkable object. Measurements confirm that J1007+3540 is hosted by MaxBCG J151.77665+35.67813, residing within the WHL 100706.4+354041 cluster. Experiments revealed clear signatures of recurrent jet activity within the source at both radio frequencies, characterised by a one-sided, extended, tail-like structure exhibiting a distinct morphological break.

The team measured radiative ages of 140 Myr for the inner lobes and 240 Myr for the outer north lobe, providing a timeline for the galaxy’s energetic outbursts. Further analysis incorporated optical-to-infrared spectral energy distribution data, establishing the host galaxy as an evolved elliptical system with a stellar mass of and an old stellar population age of 12 Gyr. Data shows a surprisingly high infrared-derived star formation rate of ~yr, indicating significant dust-obscured star formation potentially driven by merger-induced gas inflows. Tests prove J1007+3540 possesses a rare combination of a restarted jet, a detached tail-like structure, and unusual spectral flattening beyond the tail break, a configuration rarely observed in GRGs.

The LoTSS DR2 image at 144MHz, with a 6′′ resolution, clearly depicts the radio emission overlaid on an optical image, while the 20′′ beam low-resolution map effectively captures the extended tail of diffuse emission. Scientists recorded a comoving distance to J1007+3540 and determined the largest angular size (LAS) to be 552′′ at a redshift of z= 0.14335±0.00002. The research identified a point-like source, R1, coinciding with a weak optical counterpart, but with a photometric redshift of z= 0.588±0.411, distinct from the GRG’s redshift, suggesting it is a background object. Analysis of the WHL J100706.4+354041 cluster, using a redshift offset of δz= 0.01, revealed twenty-eight identified galaxies within a radius of 0.89 Mpc, concentrated towards the cluster centre. This breakthrough delivers a unique laboratory for probing the interplay between active galactic nucleus activity, star formation, and environmental effects in cluster-surrounded GRGs.

J1007+3540’s Restarted Jet, Tail and Flattening reveal a

Scientists have presented a detailed multi-wavelength analysis of J1007+3540, a giant radio galaxy (GRG) extending 1.45 Mpc, hosted by an elliptical galaxy within the WHL J100706.4+354041 cluster. Observations using LOFAR and the uGMRT revealed evidence of recurrent, episodic jet activity, with inner lobes estimated to be 140 million years old and an outer lobe reaching 240 million years old. The source exhibits a one-sided, tail-like structure with a distinct morphological break, indicating complex interactions between the radio jets and the intracluster medium (ICM). This research establishes a rare combination of features in J1007+3540: a restarted jet, a detached tail, and unusual spectral flattening beyond the tail break, a configuration seldom observed together in GRGs.

Spectral analysis indicates relic plasma in the outer lobe and potential re-acceleration processes occurring in the extended tail, possibly driven by interaction with the ICM. Furthermore, spectral energy distribution modelling suggests the host galaxy is an evolved elliptical with significant dust-obscured star formation, potentially fuelled by mergers or a rejuvenated accretion episode. The authors acknowledge limitations including the absence of deep X-ray imaging and intermediate-frequency radio data, but suggest future multi-wavelength studies, particularly in X-ray, will be crucial to further understanding the interplay between the active galactic nucleus, star formation, and the surrounding cluster environment.