A VLBI Proper Motion Analysis of the Recoiling Supermassive Black Hole Candidate Mrk 1018

Walsh, Gregory; Burke-Spolaor, S.; Lazio, T. Joseph W.

doi:10.3847/1538-4357/acda96

Cited by 2 publications

(3 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Instead, it is probable that larger-scale emission components with steeper spectra are being resolved out by the higher-frequency, higher-resolution observations, leaving only the most compact features as the sole contributor to the recovered flux density and causing the spectrum to flatten. Indeed, the flat-spectrum nature of J0206 −0017 was confirmed by Walsh et al (2023). We expect that higher-frequency observations of J1511+2309 would confirm the presence of a flat-spectrum object in this source.…”

Section: Radio Spectramentioning

confidence: 61%

“…J0206−0017, J1433+3444, and J1511+0417 are the most likely sources to contain a dominant radio core when considering their unresolved morphology and flat spectral index values (Table 3). Indeed, this is the case for J0206 −0017, as VLBI observations by Walsh et al (2023) revealed that the radio emission remains compact down to parsec scale, retains its flat spectral index, and shows chromatic variation in its position, confirming its radio-core nature. J0851+4050, J0916+4542, J1113+2714, and J1517+0409 only have lower limits to their spectral index value so the true nature of their radio AGN emission is ambiguous.…”

Section: Radio Agn Morphologiesmentioning

confidence: 72%

“…A.1. J0206−0017 J0206−0017 is a radio AGN associated with the changinglook AGN Mrk 1018 (McElroy et al 2016;Walsh et al 2023). The radio emission is resolved by FIRST and unresolved by RACS, and at 3 GHz and 10 GHz (Figure A1).…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Prevalence of Compact Nuclear Radio Emission in Post-merger Galaxies and Its Origin

Walsh,

Burke-Spolaor

2024

ApJ

View full text Add to dashboard Cite

Post-merger galaxies are unique laboratories to study the triggering and interplay of star formation and active galactic nucleus (AGN) activity. Combining new, high-resolution Jansky Very Large Array (VLA) observations with archival radio surveys, we have examined the radio properties of 28 spheroidal post-merger galaxies. We detect 18 radio sources in our post-merger sample and find a general lack of extended emission at (sub)kiloparsec scales, indicating the prevalence of compact, nuclear radio emission in these post-merger galaxies, with the majority (16/18; 89%) characterized as low luminosity. Using multiwavelength data, we determine the origin of the radio emission, discovering 15 new radio AGNs and three radio sources likely associated with star-forming (SF) processes. Among the radio AGNs, almost all are low luminosity (13/15; 87%), inconsistent with a relativistic jet origin. We discover a new dual AGN (DAGN) candidate, J1511+0417, and investigate the radio properties of the DAGN candidate J0843+3549. Five of these radio AGNs are hosted by a SF or SF-AGN composite emission-line galaxy, suggesting that radio AGN activity may be present during periods of SF activity in post-mergers. The low-power jets and compact morphologies of these radio AGNs also point to a scenario in which AGN feedback may be efficient in this sample of post-mergers. Lastly, we present simulated, multifrequency observations of the 15 radio AGNs with the Very Long Baseline Array and the very-long-baseline interferometry capabilities of the Next-Generation VLA to assess the feasibility of these instruments in searches for supermassive black hole binaries.

show abstract

Section: Radio Spectramentioning

confidence: 61%

Section: Radio Agn Morphologiesmentioning

confidence: 72%

See 1 more Smart Citation

Prevalence of Compact Nuclear Radio Emission in Post-merger Galaxies and Its Origin

Walsh,

Burke-Spolaor

2024

ApJ

View full text Add to dashboard Cite

show abstract

Interpreting the long-term variability of the changing-look AGN Mrk 1018

Veronese,

Vignali,

Severgnini

et al. 2024

A&A

View full text Add to dashboard Cite

We present a comprehensive study of the changing-look active galactic nucleus (CL-AGN) Mrk 1018 based on the largest dataset of optical, UV, and X-ray spectro-photometric data ever assembled for this source. Our investigation comprises a detailed analysis of X-ray spectra, broad-band photometry, and optical-to-X-ray spectral energy distribution (SED) fitting, with the aim being to unravel the nature of the changing-look behavior observed in Mrk 1018 between 2005 and 2019. Based on the results of our analysis, we confirm that, in those 14 years, the X-rays from the source underwent a significant spectral variation, with the hardness ratio between the 0.5-2 keV band and the 2-10 keV band increasing from 0.2 pm 0.1 to 0.4 pm 0.1. We also validate the dramatic broad-band dimming, with the optical, UV, and X-ray luminosities decreasing by a factor of $>7$, $>24,$ and $ respectively. We find that the declining UV emission is driving these drops. By describing the X-ray spectra with a two-Comptonization model, with a hot ($kT 100 keV) and a warm ($kT<1$ keV) Comptonizing medium reprocessing the photons from the accretion disk, we reach the conclusion that, between 2005 and 2019, the properties of the hot medium remained the same, while the warm component cooled down from a temperature of $ keV to $ keV. This cooling can be explained by the weakening of the magnetic fields in the accretion disk and is also the source of the UV dimming. We propose that this decline is caused by the formation of a jet, itself originating from the change in the state of the inner accretion flow from a geometrically thin, optically thick structure to a geometrically thick, optically thin flow. Our optical-to-X-ray SED fitting seems to support this conclusion, as the estimated accretion rate normalized to the Eddington rate in the bright state ($ is above the critical value $ for a stable radiative flow, while in the faint state we find $ which is compatible with advective accretion. Instabilities arising at the interface of the state transition are then able to reduce the viscous timescale from $ years to the observed $ years of Mrk 1018 variability, reconciling all the observational properties of this CL-AGN into a complex but elegant physically motivated framework. Finally, we explored a possible mechanism triggering the state transition of the inner accretion flow. Our speculation is that gaseous clouds are pushed onto the innermost regions of the AGN by a galactic (dynamical friction) and/or an extragalactic process (wet merger, cold chaotic accretion). When one of these clouds passes by, it deposits material onto the accretion disk, causing the accretion flow to ``puff up'', establishing the state transition. If this scenario is confirmed by future numerical simulations, it will open a new branch of study to place CL-AGN into our current understanding of the feeding and feedback of AGN. We also think that our results can be applied to other CL-AGN as well, and speculate that an accretion rate of $ coupled with minor ``disturbances'' in the accretion disk, could indeed be the primary factor prompting the complex changing-look phenomenon.

show abstract

A VLBI Proper Motion Analysis of the Recoiling Supermassive Black Hole Candidate Mrk 1018

Cited by 2 publications

References 69 publications

Prevalence of Compact Nuclear Radio Emission in Post-merger Galaxies and Its Origin

Prevalence of Compact Nuclear Radio Emission in Post-merger Galaxies and Its Origin

Interpreting the long-term variability of the changing-look AGN Mrk 1018

Contact Info

Product

Resources

About