The great Kite in the sky: a LOFAR observation of the radio source in Abell 2626

Abstract

The radio source at the center of the galaxy cluster Abell 2626, also known as the Kite, stands out for its unique morphology composed of four, symmetric arcs. Previous studies have probed the properties of this source at different frequencies and its interplay with the surrounding thermal plasma, but the puzzle of its origin is still unsolved. We use new LOw Frequency ARray (LOFAR) observation from the LOFAR Two-meter Sky Survey at 144 MHz to investigate the origin of the Kite.} We present a detailed analysis of the new radio data which we combined with archival radio and X-ray observations. We have produced a new, resolved spectral index map of the source with a resolution of 7${}^{\prime \prime }$ and we studied the spatial correlation of radio and X-ray emission to investigate the interplay between thermal and non-thermal plasma. The new LOFAR data have changed our view of the Kite by discovering two steep-spectrum ($\alpha <-1.5$) plumes of emission connected to the arcs. The spectral analysis shows, for the first time, a spatial trend of the spectrum along the arcs with evidence of curved synchrotron spectra and a spatial correlation with the X-ray surface brightness. On the basis of our results, we propose that the Kite was originally an X-shaped radio galaxy whose fossil radio plasma, after the end of the activity of the central active galactic nucleus, has been compressed due to motions of the thermal plasma in which it is encompassed. The interplay between the compression and advection of the fossil plasma, with the restarting of the nuclear activity of the central galaxy, could have enhanced the radio emission of the fossil plasma producing the arcs of the Kite. We present also the first, low-frequency observation of a jellyfish galaxy in the same field, in which we detect extended, low-frequency emission without a counterpart at higher frequencies.

10 pages, 7 figures. Accepted for publication on Astronomy & Astrophysics on 23/09/2020

References in corpus (17)

• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• The origin of cold fronts in the cores of relaxed galaxy clusters
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• Radio interferometric gain calibration as a complex optimization problem
• A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed
• Non-linear Kalman filters for calibration in radio interferometry
• GMRT observations of X-shaped radio sources
• GASP XXIII: A jellyfish galaxy as an astrophysical laboratory of the baryonic cycle
• Hydrodynamical Backflow in X-shaped Radio Galaxy PKS 2014-55
• NGC 326: X-shaped no more
• A systematic search for X-ray cavities in galaxy clusters, groups, and elliptical galaxies
• Revived Fossil Plasma Sources in Galaxy Clusters
• Physical properties of the X-ray gas as a dynamical diagnosis for galaxy clusters
• XMM-Newton and Chandra Observations of Abell 2626: Interacting Radio Jets and Cooling Core with Jet Precession?
• Multifrequency JVLA observations of the X-shaped radio galaxy in Abell 3670
• Discovery of a fourth arc in Abell 2626 at 610 MHz with the GMRT: Spectral properties and possibilities for the origin

Cited by in corpus (15)

• The Planck clusters in the LOFAR sky. I. LoTSS-DR2: new detections and sample overview
• LoTSS jellyfish galaxies: I. Radio tails in low redshift clusters
• Simulating the transport of relativistic electrons and magnetic fields injected by radio galaxies in the intracluster medium
• The galaxy group NGC 507: newly detected AGN remnant plasma transported by sloshing
• Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA
• GASP XXXVIII: The LOFAR-MeerKAT-VLA view on the non-thermal side of a jellyfish galaxy
• Modelling X-shaped Radio Galaxies: Dynamical and Emission Signatures from the Back-flow model
• Walk on the Low Side: LOFAR explores the low-frequency radio emission of GASP jellyfish galaxies
• Simulations of Precessing Jets and the Formation of X-shaped Radio Galaxies
• A low frequency sub-arcsecond view of powerful radio galaxies in rich-cluster environments: 3C 34 and 3C 320
• Role of magnetic fields in ram pressure stripped galaxies
• GASP XXXIX: MeerKAT hunts Jellyfish in A2626
• The structure of the giant radio fossil in the Ophiuchus galaxy cluster
• Resurging from the ashes: A spectral study of seven candidate revived radio fossils in nearby low-mass galaxy clusters
• MeerKAT 21-cm HI imaging of Abell 2626 and beyond