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dc.contributor.authorShulevski, A.
dc.contributor.authorMorganti, R.
dc.contributor.authorHarwood, J. J.
dc.contributor.authorBarthel, P. D.
dc.contributor.authorJamrozy, M.
dc.contributor.authorBrienza, M.
dc.contributor.authorBrunetti, G.
dc.contributor.authorRöttgering, H. J.A.
dc.contributor.authorMurgia, M.
dc.contributor.authorWhite, G. J.
dc.contributor.authorCroston, J. H.
dc.contributor.authorBrüggen, M.
dc.date.accessioned2018-09-20T09:12:13Z
dc.date.available2018-09-20T09:12:13Z
dc.date.issued2017-04-01
dc.identifier.citationShulevski , A , Morganti , R , Harwood , J J , Barthel , P D , Jamrozy , M , Brienza , M , Brunetti , G , Röttgering , H J A , Murgia , M , White , G J , Croston , J H & Brüggen , M 2017 , ' Radiative age mapping of the remnant radio galaxy B2 0924+30 : The LOFAR perspective ' , Astronomy and Astrophysics , vol. 600 , A65 . https://doi.org/10.1051/0004-6361/201630008
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 14960049
dc.identifier.otherPURE UUID: e8399a30-d8d1-4028-b58c-2e8f50623b90
dc.identifier.otherScopus: 85017026840
dc.identifier.otherORCID: /0000-0003-0251-6126/work/62748327
dc.identifier.urihttp://hdl.handle.net/2299/20627
dc.descriptionReproduced with permission from Astronomy & Astrophysics. © 2018 ESO.
dc.description.abstractWe have observed the steep spectrum radio source B2 0924+30 using the LOw Frequency ARray (LOFAR) telescope. Hosted by a z = 0.026 elliptical galaxy, it has a relatively large angular size of 12′ (corresponding to 360 kpc projected linear size) and a morphology reminiscent of a remnant Fanaroff-Riley type II (FRII) radio galaxy. Studying active galactic nuclei (AGN) radio remnants can give us insight into the time-scales involved into the episodic gas accretion by AGNs and their dependence on the AGN host environment. The proximity of the radio galaxy allows us to make detailed studies of its radio structure and map its spectral index and radiative age distribution. We combine LOFAR and archival images to study the spectral properties at a spatial resolution of 1′. We derive low frequency spectral index maps and use synchrotron ageing models to infer ages for different regions of the source. Thus, we are able to extend the spectral ageing studies into a hitherto unexplored frequency band, adding more robustness to our results. Our detailed spectral index mapping, while agreeing with earlier lower resolution studies, shows flattening of the spectral index towards the outer edges of the lobes. The spectral index of the lobes is α140 609∼ -1 and gradually steepens to α140 609∼ -1.8 moving towards the inner edges of the lobes. Using radiative ageing model fitting we show that the AGN activity ceased around 50 Myr ago. We note that the outer regions of the lobes are younger than the inner regions which is interpreted as a sign that those regions are remnant hotspots. We demonstrate the usefulness of maps of AGN radio remnants taken at low frequencies and suggest caution over the interpretation of spectral ages derived from integrated flux density measurements versus age mapping. The spectral index properties as well as the derived ages of B2 0924+30 are consistent with it being an FRII AGN radio remnant. LOFAR data are proving to be instrumental in extending our studies to the lowest radio frequencies and enabling analysis of the oldest source regions.en
dc.language.isoeng
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsOpen
dc.subjectGalaxies: active
dc.subjectGalaxies: individual: B2 0924+30
dc.subjectRadio continuum: galaxies
dc.subjectAstronomy and Astrophysics
dc.subjectSpace and Planetary Science
dc.titleRadiative age mapping of the remnant radio galaxy B2 0924+30 : The LOFAR perspectiveen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.identifier.urlhttp://www.scopus.com/inward/record.url?scp=85017026840&partnerID=8YFLogxK
dc.identifier.urlhttps://arxiv.org/abs/1701.06903
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeFinal Published version
dcterms.dateAccepted2017-04-01
rioxxterms.versionVoR
rioxxterms.versionofrecordhttps://doi.org/10.1051/0004-6361/201630008
rioxxterms.licenseref.uriOther
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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