(M.A. Horton, 2025) ================================================================================ LoTSS DR2 visual classifications and precession indicators M.A. Horton, Authors ? =References ? ================================================================================ Keywords: astronomical databases -- catalogs -- radio continuum: galaxies Objects: ----------------------------------------- RA (2000) DE Designation(s) ----------------------------------------- Abstract: The LOw Frequency ARray Two-metre Sky Survey second data release (LoTSS DR2) covers 27\% of the northern sky and contains around four million radio sources. The development of this catalogue involved a large citizen science project (Radio Galaxy Zoo: LOFAR) with more than 116,000 resolved sources going through visual inspection. We took a subset of sources with flux density above 75 mJy and an angular size of $90''$ or greater, giving a total of $9,985$ sources or $\sim 10\%$ of the visually inspected sources. We classified these by visual inspection in terms of broad source type (e.g., Fanaroff-Riley class I or II, narrow or wide-angle tail, relaxed double), noticeable features (wings, visible jets, banding, filaments etc), environmental features (cluster environment, merger, diffuse emission). Our specific aim was to search for features linked to jet precession, such as a misaligned jet axis, curvature and multiple hotspots. This combination of features and morphology allowed us to detect increasingly fine-grained sub- populations of interesting or unusual sources. We found that $28\%$ of sources showed evidence of one or more precession indicators, which could make them candidates for hosting close binary supermassive black holes. Potential precession signatures occur in sources of all sizes and luminosities in our sample but appear to favour more massive host galaxies. Our work greatly expands the sample size and parameter space of searches for precession signatures in powerful jetted sources. This work also showcases the diversity of large bright radio sources in the LOFAR surveys, whether or not precession indicators are present. Description: Visual inspection of large, bright sources from LoTSS DR2 File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . this file final_classifications_horton_et_al_2025.txt 177 9985 Visual classifications and precession indicators for extended radio sources from LoTSS DR2 -------------------------------------------------------------------------------- Byte-by-byte Description of file: final_classifications_horton_et_al_2025.txt -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 23 A23 --- Source_Name Name of the source from the LoTSS DR2 optical ID catalogue 25- 47 E23.17 --- z_best [0.0/4.74]? Best estimate of the source redshift 49- 71 F23.17 --- Size [0.04/6922.08]? Source physical size in kpc 73- 95 E23.17 --- L_144 ? Source radio luminosity in W/Hz at 144 MHz 97-116 F20.16 --- Mass_median [4.24/12.01]? Base 10 logarithm of source host galaxy stellar mass estimate in solar masses 118-118 I1 --- flag_mass Mass quality flag (do not use if flag_mass==0 120-120 I1 --- fri Boolean, source is an FRI 122-122 I1 --- frii Boolean, source is an FRII 124-124 I1 --- hybrid Boolean, source is a hybrid as described in the paper 126-126 I1 --- spiral Boolean, source is a spiral galaxy 128-128 I1 --- relaxed Boolean, source is a relaxed double 130-130 I1 --- cshaped Boolean, source is c-shaped 132-132 I1 --- sshaped Boolean, source is s-shaped 134-134 I1 --- misaligned Boolean, source is misaligned 136-136 I1 --- wings Boolean, source has wings 138-138 I1 --- xshaped Boolean, source is x-shaped 140-140 I1 --- straight Boolean, source has a straight jet 142-142 I1 --- multihotspots Boolean, source has multiple hotspots in one or both lobes 144-144 I1 --- continuous Boolean, source has a continuous jet 146-146 I1 --- banding Boolean, source shows banding structure 148-148 I1 --- onesided Boolean, source is one-sided 150-150 I1 --- restarted Boolean, source shows signs of having restarted 152-152 I1 --- cluster Boolean, source is a cluster member 154-154 I1 --- merger Boolean, source is a merger 156-156 I1 --- diffuse Boolean, source has diffuse structure only 158-158 I1 --- unknown Boolean, source classification is unknown 160-161 I2 --- featurecount Total number of features identified 163-163 I1 --- hasanyone Source has any one precession indicator 165-165 I1 --- hasanytwo Source has any two precession indicators 167-167 I1 --- hasall Source has all three precession indicators used in the paper 169-169 I1 --- has_exactly_1 Source has exactly one precession indicator 171-171 I1 --- has_exactly_2 Source has exactly two precession indicators 173-173 I1 --- se Source shows s symmetry and misalignment 175-175 I1 --- ms Source shows s symmetry and multiple hotspots 177-177 I1 --- em Source shows multiple hotspots and misalignment -------------------------------------------------------------------------------- See also: http://lofar-surveys.org/dr2_release.html : LOFAR surveys website Acknowledgements: References: ================================================================================ (prepared by author / pyreadme )