J/other/NatAs/8.ivo://CDS.VizieR/J/other/NatAs/8.786doi:10.26093/cds/vizier/dt/ikhigCDSGroeneveld C.van Weeren R.J.Osinga E.Williams W.L.Callingham J.R.,de Gasperin F.Botteon A.Shimwell T.Sweijen F.de Jong J.M.G.H.J.,Jansen L.F.Miley G.K.Brunetti G.Bruggen M.Rottgering H.J.A.2026-03-04T20:03:42Z2024-07-25T13:50:25ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frradio-sourcesThe largely unexplored decametre radio band (10-30MHz) provides a unique window for studying a range of astronomical topics, such as auroral emission from exoplanets, inefficient cosmic ray acceleration mechanisms and fossil radio plasma. The scarcity of low-frequency studies is mainly due to severe ionospheric corruption. Here we present a calibration strategy to correct for the ionosphere in the decametre band. We apply this to an observation from the Low-Frequency Array (LOFAR) between 16 and 30MHz. The resulting image covers 330 square degrees of sky at a resolution of 45", reaching a sensitivity of 12mJy per beam, which is an improvement by an order of magnitude in terms of sensitivity and resolution compared to previous decametre observations. Residual ionospheric effects cause additional blurring between 60" and 100". We have identified four fossil plasma sources in the surveyed region. These sources probably harbour rejuvenated radio plasma from past active galactic nuclei outbursts. Three are near the centre of low-mass galaxy clusters. Notably, two of these sources display the steepest radio spectral index among all the sources detected at 23MHz. This indicates that fossil plasma sources constitute the primary population of steep-spectrum sources at these frequencies, emphasizing the large discovery potential of ground-based decametre observations.2024NatAs...8..786Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/NatAs/8.786CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/NatAs/8.786https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/NatAs/8.786http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/NatAs/8.786https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/other/NatAs/8.786https://vizier.iucaa.in/viz-bin/votable?-source=J/other/NatAs/8.786http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/other/NatAs/8.786GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/other/NatAs/8.786/catalog (Decameter catalogue)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/other/NatAs/8.786/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/other/NatAs/8.786/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/other/NatAs/8.786/catalog?GETtext/xml+votable180.050000true77.388667.05440.0055555555555555564/117 119 215 431 441-443 446 489-491 5/375 381-383 501 503 509-511 852-853 855 885 1719 1721-1723 1761-1763 1776 1778-1779 1782-1783 1789-1791 1953-1955 1968 1970-1971 1976-1978 6/1407 1493 1495 1521 1523 1869 2001 2011 2035 3399 3405 3416-3418 3431 3437 3536-3537 3539 6863 6870-6871 6873-6875 6883 6971 6974 7018-7019 7022 7041-7043 7108 7110-7111 7122 7126-7127 7152-7153 7155 7739 7809-7811 7876 7878 7898 7916-79181.987820826661144e-26 1.987820826661144e-26https://cdsarc.cds.unistra.fr/viz-bin/moc/J/other/NatAs/8.786?format=asciiRadiodefaultJ/other/NatAs/8.786/catalogDecameter cataloguerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameIdentifier (ILTJHHMMSS+DDMMSS)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainSintTotal flux at 16-30MHzJyphot.flux.density;em.radio.20-100MHzdoublee_SintTotal flux at 16-30MHz errorJystat.errordoubleSpeakPeak flux at 16-30MHzJy/beamphot.flux.density;em.radio.20-100MHzdoublee_SpeakPeak flux at 16-30MHz errorJy/beamstat.errordouble