CosmoDRAGoN III: Shaping the Afterlife -- How Progenitors and Environments Sculpt Radio Galaxy Remnants

Fuente: arXiv
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Main Authors: Stewart, Georgia S. C., Shabala, Stanislav S., Yates-Jones, Patrick M., Turner, Ross J., Morganti, Raffaella, Krause, Martin G. H., Wong, O. Ivy, Power, Chris, Hardcastle, Martin J.
Format: Preprint
Published: 2026
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author Stewart, Georgia S. C.
Shabala, Stanislav S.
Yates-Jones, Patrick M.
Turner, Ross J.
Morganti, Raffaella
Krause, Martin G. H.
Wong, O. Ivy
Power, Chris
Hardcastle, Martin J.
author_facet Stewart, Georgia S. C.
Shabala, Stanislav S.
Yates-Jones, Patrick M.
Turner, Ross J.
Morganti, Raffaella
Krause, Martin G. H.
Wong, O. Ivy
Power, Chris
Hardcastle, Martin J.
contents Identifying remnant radio-loud active galactic nuclei (AGNs) is challenging due to their diverse morphological and spectral characteristics. Using three-dimensional hydrodynamic simulations of 15 radio galaxies, we investigate how the spectral evolution of remnants depends on progenitor power, active lifetime, environment, and underlying dynamics. The simulations span low-density group and high-density cluster environments re-gridded from smooth-particle-hydrodynamic cosmological simulations. The resulting remnants exhibit a wide range of morphologies, from amorphous structures to double-lobed forms. We find that jet power correlates with the spectral slope. As the remnant lobes evolve, we find surface brightness depends strongly on environment: group remnants are systematically dimmer and more amorphous than cluster remnants, highlighting a potential observational bias against these low-surface-brightness sources. In our models, we estimate that the peak surface brightness of a low-redshift, 50 Myr-old remnant from a low-power progenitor in a 10^{13} M_sun group environment should be routinely detectable at the 3σ level with LOFAR, although 20-30% of the emission would remain undetectable within a reasonable integration time. We find young remnants exhibit low-frequency (150-1400 MHz) spectral indices that overlap with active sources, and follow a consistent and established spectral-evolution sequence: significant curvature (α_{1400}^{6000} - α_{150}^{1400} > 0.5) develops before an ultra-steep low-frequency index (α_{150}^{1400} > 1.2). The results presented in this work are intended as a reference point for current and upcoming low-frequency studies of radio remnants.
format Preprint
id arxiv_https___arxiv_org_abs_2605_10156
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CosmoDRAGoN III: Shaping the Afterlife -- How Progenitors and Environments Sculpt Radio Galaxy Remnants
Stewart, Georgia S. C.
Shabala, Stanislav S.
Yates-Jones, Patrick M.
Turner, Ross J.
Morganti, Raffaella
Krause, Martin G. H.
Wong, O. Ivy
Power, Chris
Hardcastle, Martin J.
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
Identifying remnant radio-loud active galactic nuclei (AGNs) is challenging due to their diverse morphological and spectral characteristics. Using three-dimensional hydrodynamic simulations of 15 radio galaxies, we investigate how the spectral evolution of remnants depends on progenitor power, active lifetime, environment, and underlying dynamics. The simulations span low-density group and high-density cluster environments re-gridded from smooth-particle-hydrodynamic cosmological simulations. The resulting remnants exhibit a wide range of morphologies, from amorphous structures to double-lobed forms. We find that jet power correlates with the spectral slope. As the remnant lobes evolve, we find surface brightness depends strongly on environment: group remnants are systematically dimmer and more amorphous than cluster remnants, highlighting a potential observational bias against these low-surface-brightness sources. In our models, we estimate that the peak surface brightness of a low-redshift, 50 Myr-old remnant from a low-power progenitor in a 10^{13} M_sun group environment should be routinely detectable at the 3σ level with LOFAR, although 20-30% of the emission would remain undetectable within a reasonable integration time. We find young remnants exhibit low-frequency (150-1400 MHz) spectral indices that overlap with active sources, and follow a consistent and established spectral-evolution sequence: significant curvature (α_{1400}^{6000} - α_{150}^{1400} > 0.5) develops before an ultra-steep low-frequency index (α_{150}^{1400} > 1.2). The results presented in this work are intended as a reference point for current and upcoming low-frequency studies of radio remnants.
title CosmoDRAGoN III: Shaping the Afterlife -- How Progenitors and Environments Sculpt Radio Galaxy Remnants
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.10156