Parsec-scale radio morphology and variability of a changing-look AGN: the case of Mrk 590

Abstract

We investigate the origin of the parsec-scale radio emission from the changing-look active galactic nucleus (AGN) of Mrk 590, and examine whether the radio power has faded concurrently with the dramatic decrease in accretion rates observed between the 1990s and the present. We detect a compact core at 1.6 GHz and 8.4 GHz using new Very Long Baseline Array observations, finding no significant extended, jet-like features down to $\sim$1 pc scales. The flat spectral index (${\alpha }_{1.6}^{8.4}=0.03$) and high brightness temperature ($T_{\mathrm{b}}\sim 10^8\mathrm{K}$) indicate self-absorbed synchrotron emission from the AGN. The radio to X-ray luminosity ratio of $\log (L_{\mathrm{R}}/L_{\mathrm{X}})\sim -5$, similar to that in coronally active stars, suggests emission from magnetized coronal winds, although unresolved radio jets are also consistent with the data. Comparing new Karl G. Jansky Very Large Array measurements with archival and published radio flux densities, we find $46\%$, $34\%$, and (insignificantly) $13\%$ flux density decreases between the 1990s and the year 2015 at 1.4 GHz, 5 GHz and 8.4 GHz respectively. This trend, possibly due to the expansion and fading of internal shocks within the radio-emitting outflow after a recent outburst, is consistent with the decline of the optical-UV and X-ray luminosities over the same period. Such correlated variability demonstrates the AGN accretion-outflow connection, confirming that the changing-look behaviour in Mrk 590 originates from variable accretion rates rather than dust obscuration. The present radio and X-ray luminosity correlation, consistent with low/hard state accretion, suggests that the black hole may now be accreting in a radiatively inefficient mode.

14 pages, 5 tables, 5 figures, accepted for publication in MNRAS

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Cited by in corpus (17)

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• A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN hosted by NGC404
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• Rapid Luminosity Decline and Subsequent Reformation of the Innermost Dust Distribution in the Changing-look AGN Mrk 590
• Long-term and multi-wavelength evolution of a changing-look AGN Mrk 1018
• Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A
• Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales
• Flares in the changing look AGN Mrk 590. I: The UV response to X-ray outbursts suggests a more complex reprocessing geometry than a standard disk
• A candidate relativistic tidal disruption event at 340 Mpc
• A parsec-scale faint jet in the nearby changing-look Seyfert galaxy Mrk 590
• Changing-look AGNs or short-lived radio sources?
• A compact core-jet structure in the changing-look Seyfert NGC 2617
• The nascent milliquasar VT J154843.06+220812.6: tidal disruption event or extreme accretion-state change?
• A jet-dominated model for a broad-band spectral energy distribution of the nearby low-luminosity active galactic nucleus in M94
• Extreme variability quasars from the Sloan Digital Sky Survey and the Dark Energy Survey