A Caltech Library Service

Characterizing Compact 15-33 GHz Radio Continuum Sources in Local U/LIRGs

Song, Y. and Linden, S. T. and Evans, A. S. and Barcos-Muñoz, L. and Murphy, E. J. and Momjian, E. and Díaz-Santos, T. and Larson, K. L. and Privon, G. C. and Huang, X. and Armus, L. and Mazzarella, J. M. and U, V. and Inami, H. and Charmandaris, V. and Ricci, C. and Emig, K. L. and McKinney, J. and Yoon, I. and Kunneriath, D. and Lai, T. S.-Y. and Rodas-Quito, E. E. and Saravia, A. and Gao, T. and Meynardie, W. and Sanders, D. B. (2022) Characterizing Compact 15-33 GHz Radio Continuum Sources in Local U/LIRGs. Astrophysical Journal, 940 (1). Art. No. 52. ISSN 0004-637X. doi:10.3847/1538-4357/ac923b.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


We present the analysis of ∼100 pc scale compact radio continuum sources detected in 63 local (ultra)luminous infrared galaxies (U/LIRGs; L_(IR) ≥ 10¹¹ L_(⊙)), using FWHM ≲ 0".1–0".2 resolution 15 and 33 GHz observations with the Karl G. Jansky Very Large Array. We identify a total of 133 compact radio sources with effective radii of 8-170 pc, which are classified into four main categories — "AGN" (active galactic nuclei), "AGN/SBnuc" (AGN-starburst composite nucleus), "SBnuc" (starburst nucleus), and "SF" (star-forming clumps) — based on ancillary data sets and the literature. We find that "AGN" and "AGN/SBnuc" more frequently occur in late-stage mergers and have up to 3 dex higher 33 GHz luminosities and surface densities compared with "SBnuc" and "SF," which may be attributed to extreme nuclear starburst and/or AGN activity in the former. Star formation rates (SFRs) and surface densities (Σ_(SFR)) are measured for "SF" and "SBnuc" using both the total 33 GHz continuum emission (SFR ∼ 0.14–13 M_⊙ yr⁻¹, Σ_(SFR) ∼ 13–1600 M_⊙ yr⁻¹ kpc⁻²) and the thermal free–free emission from H ii regions (median SFRth ∼ 0.4 M⊙ yr⁻¹, Σ_[(SFR)_(th)] ~ 44 M_⊙ yr⁻¹ kpc⁻²). These values are 1–2 dex higher than those measured for similar-sized clumps in nearby normal (non-U/LIRGs). The latter also have a much flatter median 15–33 GHz spectral index (∼−0.08) compared with "SBnuc" and "SF" (∼−0.46), which may reflect higher nonthermal contribution from supernovae and/or interstellar medium densities in local U/LIRGs that directly result from and/or lead to their extreme star-forming activities on 100 pc scales.

Item Type:Article
Related URLs:
URLURL TypeDescription
Song, Y.0000-0002-3139-3041
Linden, S. T.0000-0002-1000-6081
Evans, A. S.0000-0003-2638-1334
Barcos-Muñoz, L.0000-0003-0057-8892
Murphy, E. J.0000-0001-7089-7325
Momjian, E.0000-0003-3168-5922
Díaz-Santos, T.0000-0003-0699-6083
Larson, K. L.0000-0003-3917-6460
Privon, G. C.0000-0003-3474-1125
Huang, X.0000-0003-2868-489X
Armus, L.0000-0003-3498-2973
Mazzarella, J. M.0000-0002-8204-8619
U, V.0000-0002-1912-0024
Inami, H.0000-0003-4268-0393
Charmandaris, V.0000-0002-2688-1956
Ricci, C.0000-0001-5231-2645
Emig, K. L.0000-0001-6527-6954
McKinney, J.0000-0002-6149-8178
Yoon, I.0000-0001-9163-0064
Kunneriath, D.0000-0002-1568-579X
Lai, T. S.-Y.0000-0001-8490-6632
Rodas-Quito, E. E.0000-0001-6956-0987
Saravia, A.0000-0003-4546-3810
Gao, T.0000-0002-1158-6372
Sanders, D. B.0000-0002-1233-9998
Additional Information:Y.S. would like to thank J. Molden and M. Perrez-Torres for sharing preliminary results on AGN identification using e-MERLIN, T. Thompson for providing helpful insights on comparisons with the TQM05 models, J. Hibbard for helpful discussions on locating galactic nuclei using ALMA data sets, and J. Rich for additional information on optical AGN classifications. Support for this work was provided by the NSF through the Grote Reber Fellowship Program administered by Associated Universities, Inc./National Radio Astronomy Observatory. A.S.E. and Y.S. were supported by NSF grant AST 1816838. A.S.E. was also supported by the Taiwan, ROC, Ministry of Science and Technology grant MoST 102-2119-M001-MY3. V.U. acknowledges funding support from NASA Astrophysics Data Analysis Program (ADAP) grant 80NSSC20K0450. H.I. acknowledges support from JSPS KAKENHI grant No. JP19K23462. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge the usage of the HyperLeda database (, and the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. This research made use of APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012; Robitaille 2019).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Radio Astronomy ObservatoryUNSPECIFIED
Ministry of Science and Technology (Taipei)102-2119-M001-MY3
Japan Society for the Promotion of Science (JSPS)JP19K23462
Issue or Number:1
Record Number:CaltechAUTHORS:20221202-907217500.14
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118217
Deposited By: Research Services Depository
Deposited On:05 Jan 2023 17:06
Last Modified:05 Jan 2023 17:06

Repository Staff Only: item control page