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Quasars That Have Transitioned from Radio-quiet to Radio-loud on Decadal Timescales Revealed by VLASS and FIRST

Nyland, Kristina and Dong, Dillon Z. and Patil, Pallavi and Lacy, Mark and van Velzen, Sjoert and Kimball, Amy E. and Sarbadhicary, Sumit K. and Hallinan, Gregg and Baldassare, Vivienne and Clarke, Tracy E. and Goulding, Andy D. and Greene, Jenny and Hughes, Andrew and Kassim, Namir and Kunert-Bajraszewska, Magdalena and Maccarone, Thomas J. and Mooley, Kunal and Mukherjee, Dipanjan and Peters, Wendy and Petrov, Leonid and Polisensky, Emil and Rujopakarn, Wiphu and Whittle, Mark and Vaccari, Mattia (2020) Quasars That Have Transitioned from Radio-quiet to Radio-loud on Decadal Timescales Revealed by VLASS and FIRST. Astrophysical Journal, 905 (1). Art. No. 74. ISSN 0004-637X. doi:10.3847/1538-4357/abc341.

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We have performed a search over 3440 deg² of Epoch 1 (2017–2019) of the Very Large Array Sky Survey to identify unobscured quasars in the optical (0.2 < z < 3.2) and obscured active galactic nuclei (AGNs) in the infrared that have brightened dramatically in the radio over the past one to two decades. These sources would have been previously classified as "radio-quiet" quasars based on upper limits from the Faint Images of the Radio Sky at Twenty cm survey (1993–2011), but they are now consistent with "radio-loud" quasars L_(3 GHz) = 10⁴⁰⁻⁴² erg s⁻¹. A quasi-simultaneous, multiband (~1–18 GHz) follow-up study of 14 sources with the VLA has revealed compact sources (<0."1 or <1 kpc) with peaked radio spectral shapes. The high-amplitude variability over decadal timescales at 1.5 GHz (100% to >2500%) but roughly steady fluxes over a few months at 3 GHz are inconsistent with extrinsic variability due to propagation effects, thus favoring an intrinsic origin. We conclude that our sources are powerful quasars hosting compact/young jets. This challenges the generally accepted idea that "radio-loudness" is a property of the quasar/AGN population that remains fixed on human timescales. Our study suggests that frequent episodes of short-lived AGN jets that do not necessarily grow to large scales may be common at high redshift. We speculate that intermittent but powerful jets on subgalactic scales could interact with the interstellar medium, possibly driving feedback capable of influencing galaxy evolution.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Nyland, Kristina0000-0003-1991-370X
Dong, Dillon Z.0000-0001-9584-2531
Patil, Pallavi0000-0002-9471-8499
Lacy, Mark0000-0002-3032-1783
van Velzen, Sjoert0000-0002-3859-8074
Kimball, Amy E.0000-0001-9324-6787
Sarbadhicary, Sumit K.0000-0002-4781-7291
Hallinan, Gregg0000-0002-7083-4049
Baldassare, Vivienne0000-0003-4703-7276
Clarke, Tracy E.0000-0001-6812-7938
Goulding, Andy D.0000-0003-4700-663X
Kassim, Namir0000-0001-8035-4906
Kunert-Bajraszewska, Magdalena0000-0002-6741-9856
Maccarone, Thomas J.0000-0003-0976-4755
Mooley, Kunal0000-0002-2557-5180
Mukherjee, Dipanjan0000-0003-0632-1000
Rujopakarn, Wiphu0000-0002-0303-499X
Vaccari, Mattia0000-0002-6748-0577
Additional Information:© 2020. The American Astronomical Society. Received 2020 August 17; revised 2020 October 14; accepted 2020 October 19; published 2020 December 15. We thank the anonymous referee for providing us with helpful comments that have improved the quality of this work. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Basic research in radio astronomy at the U.S. Naval Research Laboratory is supported by 6.1 Base Funding. M.K.-B. acknowledges support from the "National Science Centre, Poland" under grant No. 2017/26/E/ST9/00216. Facility: VLA. - Software: Astropy (Astropy Collaboration et al. 2013), CASA (McMullin et al. 2007), Obit (Cotton 2008), and Montage (Jacob et al. 2010; Berriman & Good 2017).
Group:Astronomy Department
Funding AgencyGrant Number
Naval Research Laboratory6.1 Base funding
National Science Centre (Poland)2017/26/E/ST9/00216
Subject Keywords:Active galaxies ; Radio sources ; Galaxy evolution ; Radio loud quasars ; Quasars ; Radio quiet quasars ; Surveys ; Radio active galactic nuclei ; Radio astronomy ; Radio jets ; Radio transient sources ; Extragalactic radio sources
Issue or Number:1
Record Number:CaltechAUTHORS:20201216-115150890
Persistent URL:
Official Citation:Kristina Nyland et al 2020 ApJ 905 74
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107122
Deposited By: George Porter
Deposited On:16 Dec 2020 21:10
Last Modified:16 Nov 2021 18:59

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