Open AccessAn extreme example of a radio relic in Abell 4038
Author(s) -
Slee O. B.,
Roy A. L.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01739.x
Subject(s) - physics , astrophysics , intracluster medium , surface brightness , astronomy , abell 2744 , radio galaxy , cluster (spacecraft) , galaxy cluster , galaxy , centroid , spectral index , brightest cluster galaxy , spectral line , geometry , mathematics , computer science , programming language
A radio source with a spectral index of −2.2 between 0.08 and 1.425 GHz has been observed at the Very Large Array (VLA) at 1.425 GHz with resolution ∼ 3 arcsec. The projected linear length of the source is 56 kpc with an average projected distance of 42 kpc from the centroid of the rich southern cluster Abell 4038, assuming the source is in the cluster. The physical parameters of the source include a high minimum‐energy field ( B me ) of 38 μG, which is unusual for a source of low surface brightness and relaxed appearance, but is explained by its unusually steep spectrum. Although its radio morphology has some characteristics of a narrow‐angle‐tail source (NAT), the absence of an identified host galaxy ( m R ≥ 23.0) makes it unlikely that the source is a working radio galaxy. The relic is probably the remains of an FR II radio galaxy that was once energized by a particular bright cluster elliptical now 18 kpc to its east. The density of the intracluster gas has been sufficient to confine the source and preserve its morphology, permitting the source to age and its spectrum to steepen through synchrotron and inverse Compton energy losses.