Combining LOFAR and Apertif Data for Understanding the Life Cycle of Radio Galaxies

Abstract

Active galactic nuclei (AGN) at the centres of galaxies can cycle between periods of activity and of quiescence. Characterising the duty-cycle of AGN is crucial for understanding their impact on the evolution of the host galaxy. For radio AGN, their evolutionary stage can be identified from a combination of morphological and spectral properties. We summarise the results we have obtained in the last few years by studying radio galaxies in various crucial phases of their lives, such as remnant and restarted sources. We used morphological information derived from LOw Frequency ARray (LOFAR) images at 150 MHz, combined with resolved spectral indices maps, obtained using recently released images at 1400 MHz from the APERture Tile In Focus (Apertif) phased-array feed system installed on the Westerbork Synthesis Radio Telescope. Our study, limited so far to the Lockman Hole region, has identified radio galaxies in the dying and restarted phases. We found large varieties in their properties, relevant for understanding their evolutionary stage. We started by quantifying their occurrences, the duration of the 'on' (active) and 'off' (dying) phase, and we compared the results with models of the evolution of radio galaxies. In addition to these extreme phases, the resolved spectral index images can also reveal interesting secrets about the evolution of apparently normal radio galaxies. The spectral information can be connected with, and used to improve, the Fanaroff--Riley classification, and we present one example of this, illustrating what the combination of the LOFAR and Apertif surveys now allow us to do routinely.

arXiv commentAccepted for publication in the special issue of Galaxies, proceedings of the conference Radio Galaxies in the Cosmic Web. 19 pages, 6 figures

References in corpus (26)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• LOFAR: The LOw-Frequency ARray
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• The host galaxies of radio-loud AGN: mass dependencies, gas cooling and AGN feedback
• Chaotic cold accretion onto black holes
• Radio galaxies with a `double-double' morphology: I - Analysis of the radio properties and evidence for interrupted activity in active galactic nuclei
• Raining on black holes and massive galaxies: the top-down multiphase condensation model
• Revisiting the Fanaroff-Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)
• Accretion Disk Model of Short-Timescale Intermittent Activity in Young Radio Sources
• Numerical modelling of the lobes of radio galaxies in cluster environments
• A simulation-based analytic model of radio galaxies
• FRII{\sl{CAT}}: A FIRST catalog of FR~II radio galaxies
• The Lockman Hole project: LOFAR observations and spectral index properties of low-frequency radio sources
• LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift
• Remnant radio-loud AGN in the Herschel-ATLAS field
• The duty cycle of radio galaxies revealed by LOFAR: remnant and restarted radio source populations in the Lockman Hole
• ATLBS Extended Source Sample: The evolution in radio source morphology with flux density
• Episodic radio galaxies J0116$-$4722 and J1158+2621: can we constrain the quiescent phase of nuclear activity?
• On the population of remnant FRII radio galaxies and implications for radio source dynamics
• Duty cycle of the radio galaxy B2 0258+35
• Double-double radio galaxies: further insights into the formation of the radio structures
• Radio spectral properties and jet duty cycle in the restarted radio galaxy 3C388
• The best of both worlds: Combining LOFAR and Apertif to derive resolved radio spectral index images
• Unmasking the history of 3C 293 with LOFAR sub-arcsecond imaging
• Radiative ages in a representative sample of low luminosity radio galaxies