LOFAR discovery and wide-band characterisation of an ultra-steep spectrum AGN radio remnant associated with Abell 1318
Artikel i vetenskaplig tidskrift, 2024

We present the discovery of a very extended (550 kpc) and low-surface-brightness (3.3 µJy arcsec−2 at 144 MHz) radio emission region in Abell 1318. These properties are consistent with its characterisation as an active galactic nucleus (AGN) remnant radio plasma, based on its morphology and radio spectral properties. We performed a broad-band (54–1400 MHz) radio spectral index and curvature analysis using LOFAR, uGMRT, and WSRT-APERTIF data. We also derived the radiative age of the detected emission, estimating a maximum age of 250 Myr. The morphology of the source is remarkably intriguing, with two larger, oval-shaped components and a thinner, elongated, and filamentary structure in between, plausibly reminiscent of two aged lobes and a jet. Based on archival Swift as well as SDSS data we performed an X-ray and optical characterisation of the system, whose virial mass was estimated to be ∼7.4 × 1013 M. This places A1318 in the galaxy group regime. Interestingly, the radio source does not have a clear optical counterpart embedded in it, thus, we propose that it is most likely an unusual AGN remnant of previous episode(s) of activity of the AGN hosted by the brightest group galaxy (∼2.6 × 1012 M), which is located at a projected distance of ∼170 kpc in the current epoch. This relatively high offset may be a result of IGrM sloshing sourced by a minor merger. The filamentary morphology of the source may suggest that the remnant plasma has been perturbed by the system dynamics, however, only future deeper X-ray observations will be able to address this question.

galaxies: active

radio continuum: galaxies

Författare

A. Shulevski

Universiteit Leiden

Anton Pannekoek Institute for Astronomy

Rijksuniversiteit Groningen

Netherlands Institute for Radio Astronomy (ASTRON)

M. Brienza

Universita di Bologna

Istituto nazionale di astrofisica (INAF)

F. Massaro

Universita degli Studi di Torino

R. Morganti

Netherlands Institute for Radio Astronomy (ASTRON)

Rijksuniversiteit Groningen

H. T. Intema

Universiteit Leiden

T. Oosterloo

Netherlands Institute for Radio Astronomy (ASTRON)

Rijksuniversiteit Groningen

F. De Gasperin

Istituto di Radioastronomia

Universität Hamburg

K. Rajpurohit

Istituto di Radioastronomia

Harvard-Smithsonian Center for Astrophysics

Universita di Bologna

T. Pasini

Universität Hamburg

A. M. Kutkin

Netherlands Institute for Radio Astronomy (ASTRON)

D. Vohl

Anton Pannekoek Institute for Astronomy

Netherlands Institute for Radio Astronomy (ASTRON)

Elizabeth A.K. Adams

Rijksuniversiteit Groningen

Netherlands Institute for Radio Astronomy (ASTRON)

B. Adebahr

Ruhr-Universität Bochum

M. Brueggen

Universität Hamburg

Kelley Michelle Hess

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

Netherlands Institute for Radio Astronomy (ASTRON)

Consejo Superior de Investigaciones Científicas (CSIC)

M. Loose

Netherlands Institute for Radio Astronomy (ASTRON)

L. C. Oostrum

Netherlands eScience Center

Anton Pannekoek Institute for Astronomy

Netherlands Institute for Radio Astronomy (ASTRON)

J. Ziemke

Universitetet i Oslo

Netherlands Institute for Radio Astronomy (ASTRON)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 682 A171

Ämneskategorier (SSIF 2011)

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/202346824

Mer information

Senast uppdaterat

2025-03-09