J/A+A/680/A98ivo://CDS.VizieR/J/A+A/680/A98doi:10.26093/cds/vizier/bc-n8/ljiCDSVohl D.Vedantham H.K.Hessels J.W.T.Bassa C.G.Cook D.O.Kaplan D.L.,Shimwell T.W.Zhang C.2026-07-03T06:35:48Z2023-12-15T10:06:18ZCDS support team

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

cds-question@unistra.frradio-sourcesgalaxiesThe vast majority of extra-galactic, compact continuum radio sources are associated with star formation or jets from (super)massive black holes and, as such, are more likely to be found in association with starburst galaxies or early type galaxies. Recently, two new populations of radio sources have been identified: (a) compact and persistent sources (PRS) associated with fast radio bursts (FRB) in dwarf galaxies and (b) compact sources in dwarf galaxies that could belong to the long-sought population of intermediate-mass black holes. Despite the interesting aspects of these newly found sources, the current sample size is small, limiting scrutiny of the underlying population. Here, we present a search for compact radio sources coincident with dwarf galaxies. We search the LOFAR Two-meter Sky Survey (LoTSS) -- the most sensitive low-frequency (144MHz central frequency) large-area survey for optically thin synchrotron emission to date. Exploiting LoTSS' high spatial resolution (6arcsec) and low astrometric uncertainty (~0.2arcsec), we match its compact sources to the compiled sample of dwarf galaxies in the Census of the Local Universe -- an H Alpha survey with the Palomar Observatory's 48-inch Samuel Oschin Telescope. We identify 29 over-luminous compact radio sources, evaluate the probability of chance alignment within the sample, investigate the potential nature of these sources, and evaluate their volumetric density and volumetric rate. While optical line-ratio diagnostics on the nebular lines from the host galaxies prefer a star-formation origin (against an AGN origin), future high angular resolution radio data is necessary to ascertain the origin of the radio sources. We discuss planned strategies to differentiate them between candidate FRB hosts and intermediate-mass black holes.2023A&A...680A..98Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/680/A98CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)J/A+A/664/A83 : Nearby galaxies in LoTSS-DR2 (Heesen+, 2022)J/A+A/669/A8 : Nearby galaxies in LoTSS-DR2. II. (Heesen+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/680/A98https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/680/A98http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/680/A98https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/680/A98https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/680/A98http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/680/A98GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/680/A98/table1 (Properties of the selected candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/680/A98/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/680/A98/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/680/A98/table1?GETtext/xml+votable180.050000true8.884833330.50222220.0055555555555555566/721 745 753 4966 5434 6099 6541 7229 9146 9416 9433 9450 9612 10156 10378-10379 10464 10516 10541 10596 10919 11389 11804 11960 12668 20031 203169.54153977050123e-26 1.987820871092403e-24https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/680/A98?format=asciiRadiodefaultJ/A+A/680/A98/table1Properties of the selected candidatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFluxesindicates fluxes from other daio catalogs in table 3meta.ref.urlcharSourceSource name in LoTSS DR2 (ILT JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharprimaryHostHost galaxy name in CLUmeta.id.parentcharProjOffProjected offset between the radio source and H{alpha} source coordinates in arcsecarcsecpos.distancefloate_ProjOffProjected offset in arcsec uncertaintyarcsecstat.errorfloatProjOffpcProjected offset between the radio source and H{alpha} source coordinates (pc)pcpos.angDistance;arith.diff;spect.lineinte_ProjOffpcProjected offset in pc uncertaintypcstat.errorfloatzRedshiftsrc.redshiftcharn_z[kmn] Distance method (1)meta.notecharSintIntegrated flux density at 144MHzmJyphot.flux.density;em.radio.100-200MHzfloate_SintIntegrated flux density at 144MHz uncertaintymJystat.errorfloatlogLRadio luminosity at 144MHzlog(W.Hz**-1)phys.luminosity;em.radiofloatlogSFRStar formation ratelog(solMass.yr**-1)phys.SFRfloate_logSFR[] Star formation rate uncertaintylog(solMass.yr**-1)stat.error;phys.SFRfloatsigma? Standard deviation above the L-SFR relationstat.stdevfloatnullablealpha? Radio spectral indexspect.indexfloatnullableRg? Radio loudnessphot.flux;arith.ratiofloatnullable_RAPosition from name (right ascension part)degpos.eq.ra;meta.main_DEPosition from name (declination part)degpos.eq.dec;meta.mainJ/A+A/680/A98/table3Fluxes for candidates matched in at least one ancillary radio surveySint-RACS? RACS (Rapid ASKAP Continuum Survey) 700-1800MHz integrated flux densitymJyphot.flux.density;em.radio.750-1500MHzfloatnullablee_Sint-RACS? RACS 700-1800MHz integrated flux density uncertaintymJystat.errorfloatnullableSint-FIRST? FIRST 1.4GHz integrated flux densitymJyphot.flux.density;em.radio.750-1500MHzfloatnullablee_Sint-FIRST? FIRST 1.4GHz integrated flux density uncertaintymJystat.errorfloatnullableSint-NVSS? NVSS 1.4GHz integrated flux densitymJyphot.flux.density;em.radio.750-1500MHzfloatnullablee_Sint-NVSS? NVSS 1.4GHz integrated flux density uncertaintymJystat.errorfloatnullableSint-VLASS? VLASS 3GHz integrated flux densitymJyphot.flux.density;em.radio.1500-3000MHzfloatnullablee_Sint-VLASS? VLASS 3GHz integrated flux density uncertaintymJystat.errorfloatnullablen_Sint-VLASS[*] Note on Sint_VLASS (1)meta.notecharalphaRadio spectral indexspect.indexfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSourceSource name in LoTSS DR2 (ILT JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharSint-LoTSSLoTSS 144MHz integrated flux densitymJyphot.flux.density;em.radio.100-200MHzfloate_Sint-LoTSSLoTSS 144MHz integrated flux density uncertaintymJystat.errorfloate_alphaRadio spectral index uncertaintystat.error;pos.eq.rafloatalpha-hf? Radio spectral index fitted between 1.4 and 3GHzphot.flux.density;em.radio.1500-3000MHzfloatnullablee_alpha-hf? Radio spectral index fitted between 1.4 and 3GHz uncertaintystat.errorfloatnullablen_alpha-hf[*] Note on alpha-hf (2)meta.notechar