J/A+A/668/A39ivo://CDS.VizieR/J/A+A/668/A39doi:10.26093/cds/vizier.36680039CDSReich W.Reich P.Kothes R.2023-01-18T06:49:45Z2022-12-01T08:23:46ZCDS support team

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

cds-question@unistra.frsupernova-remnantsradio-sourcesBreaks in the radio spectra of supernova remnants (SNRs) reflect the maximum energy of either shock-accelerated electrons or - in the case of pulsar wind nebulae - of electrons injected by the central pulsar. Otherwise, the break may result from energy losses due to synchrotron ageing or it is caused by energy-dependent diffusion. A spectral steepening of the plerionic SNR CTB87 at around 11 GHz was observed in the 1980s, but a recent analysis of CTB87's energetic properties based on new radio data raised doubt on it. CTB87 consists of a central compact component surrounded by a diffuse, centrally peaked, almost circular halo. Missing faint halo emission due to insufficient sensitivity of early high-frequency observations may be the reason for the reported spectral break. We intend to clarify the high-frequency spectrum of CTB87 by new sensitive observations. We used the broad-band 2-cm receiver at the Effelsberg 100-m telescope for sensitive continuum observations of CTB87 and its halo in two frequency bands. The new 2-cm maps of CTB87 show halo emission with a diameter of about 17' or 30pc for a distance 6.1 kpc in agreement with lower-frequency data. The measured flux densities are significantly higher than those reported earlier. The new 2-cm data establish the high-frequency continuation of CTB87's low-frequency spectrum. Any significant high-frequency spectral bend or break is constrained to frequencies well above about 18GHz. The extended halo of CTB87 has a faint counterpart in gamma-rays (VER J2016+37) and thus indicates a common origin of the emitting electrons.2022A&A...668A..39Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/668/A39CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/668/A39https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/668/A39http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/668/A39https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/668/A39https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/668/A39http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/668/A39GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/668/A39/list (List of fits maps)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/668/A39/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/668/A39/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/668/A39/list?GETtext/xml+votable180.050000true304.005100137.21146810.0055555555555555566/14641https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/668/A39?format=asciiRadiodefaultJ/A+A/668/A39/listList of fits mapsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGLONGalactic longitude of center (J2000)degpos.galactic.lonGLATGalactic latitude of center (J2000)degpos.galactic.latNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintFreqObaerved frequencyGHzem.freqfloat_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexedTitleTitle of the FITS filemeta.title;meta.fitscharsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitschar