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Caltech-NRAO Stripe 82 Survey (CNSS). V. AGNs That Transitioned to Radio-loud State

Wołowska, Aleksandra and Kunert-Bajraszewska, Magdalena and Mooley, Kunal P. and Siemiginowska, Aneta and Kharb, Preeti and Ishwara-Chandra, C. H. and Hallinan, Gregg and Gromadzki, Mariusz and Kozieł-Wierzbowska, Dorota (2021) Caltech-NRAO Stripe 82 Survey (CNSS). V. AGNs That Transitioned to Radio-loud State. Astrophysical Journal, 914 (1). Art. No. 22. ISSN 1538-4357. doi:10.3847/1538-4357/abe62d.

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A recent multiyear Caltech-NRAO Stripe 82 Survey revealed a group of objects that appeared as new radio sources after >5–20 yr of absence. They are transient phenomena with respect to the Faint Images of the Radio Sky at Twenty Centimeters survey and constitute the first unbiased sample of renewed radio activity. Here we present a follow-up, radio, optical, and X-ray study of them. The group consists of 12 sources, both quasars and galaxies with wide redshift (0.04 < z < 1.7) and luminosity (22 < log₁₀ [L_(1.4 GHz)/W Hz⁻¹] > 24.5) distributions. Their radio properties in the first phase of activity, namely the convex spectra and compact morphology, allow them all to be classified as gigahertz-peaked spectrum (GPS) sources. We conclude that the spectral changes are a consequence of the evolution of newly born radio jets. Our observations show that over the next few years of activity the GPS galaxies keep the convex shape of the spectrum, while GPS quasars rapidly transform into flat-spectrum sources, which may result in them not being recognized as young sources. The wide range of bolometric luminosities, black hole masses, and jet powers among the transient sources indicates even greater population diversity in the group of young radio objects. We also suggest that small changes of the accretion disk luminosity (accretion rate) may be sufficient to ignite low-power radio activity that evolves on the scale of decades.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Wołowska, Aleksandra0000-0002-1406-8255
Kunert-Bajraszewska, Magdalena0000-0002-6741-9856
Mooley, Kunal P.0000-0002-2557-5180
Siemiginowska, Aneta0000-0002-0905-7375
Kharb, Preeti0000-0003-3203-1613
Ishwara-Chandra, C. H.0000-0001-5356-1221
Hallinan, Gregg0000-0002-7083-4049
Gromadzki, Mariusz0000-0002-1650-1518
Kozieł-Wierzbowska, Dorota0000-0003-4323-0984
Additional Information:© 2021. The American Astronomical Society. Received 2020 December 18; revised 2021 February 11; accepted 2021 February 11; published 2021 June 9. We are grateful to Anna Wójtowicz and Łukasz Stawarz for the fruitful discussion. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the staff of the VLBA and VLA for carrying out these observations in their usual efficient manner. This work made use of the Swinburne University of Technology software correlator, developed as part of the Australian Major National Research Facilities Programme and operated under licence. We thank the staff of the GMRT who have made these observations possible. The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. P.K. and I.C.H. acknowledge the support of the Department of Atomic Energy, Government of India, under project 12-R&D-TFR-5.02-0700. Some of the observations reported in this paper were obtained with SALT under program 2019-1-SCI-023 (PI: A. Wołowska). Polish participation in SALT is funded by grant No. MNiSW DIR/WK/2016/07. This project was supported in part by NASA grant GO8-19081X (Chandra) and by NASA contract NAS8-03060 to the Chandra X-ray Center (AS). M.K.B. and A.W. acknowledge support from the "National Science Centre, Poland" under grant No. 2017/26/E/ST9/00216. K.P.M. is a Jansky Fellow of the National Radio Astronomy Observatory. K.P.M. and G.H. acknowledge support from the National Science Foundation grant AST-1911199. M.G. is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. Software: CASA (McMullin et al. 2007), AIPS (van Moorsel et al. 1996), IRAF (Tody 1986, 1993), STARLIGHT (Cid Fernandes et al. 2011), CIAO (Fruscione et al. 2006), Sherpa (Freeman et al. 2001).
Group:Astronomy Department
Funding AgencyGrant Number
Department of Atomic Energy (India)12-R&D-TFR-5.02-0700
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW)DIR/WK/2016/07
National Science Centre (Poland)2017/26/E/ST9/00216
Jansky FellowshipUNSPECIFIED
National Radio Astronomy ObservatoryUNSPECIFIED
National Science Centre (Poland)2014/14/A/ST9/00121
Subject Keywords:Active galaxies; AGN host galaxies; Radio galaxies; Quasars; Radio loud quasars; Radio quiet quasars; Supermassive black holes; Active galactic nuclei; Galaxy evolution
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Active galaxies (17); AGN host galaxies (2017); Radio galaxies (1343); Quasars (1319); Radio loud quasars (1349); Radio quiet quasars (1354); Supermassive black holes (1663); Active galactic nuclei (16);
Record Number:CaltechAUTHORS:20210322-070250837
Persistent URL:
Official Citation:Aleksandra Wołowska et al 2021 ApJ 914 22
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108497
Deposited By: Tony Diaz
Deposited On:23 Mar 2021 15:48
Last Modified:09 Jun 2021 22:01

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