The Close AGN Reference Survey (CARS)

Krumpe, M.; Tremblay, G. R.; Urrutia, T.; Powell, Meredith C.; Davis, T. A.; Scharwächter, J.; Dexter, Jason; Busch, G.; Combes, F.; Croom, S. M.; Eckart, A.; Pérez-Torres, M. Á.; Leung, Gene C. K.

doi:10.1051/0004-6361/201731967

Cited by 21 publications

(20 citation statements)

References 31 publications

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“…Figure 4 shows the evolution of the Hα emission line profile. The broad emission line appears similar in 2019 and in 2015, with some variations already reported by Krumpe et al (2017) from spectra obtained in 2016-2017. While the MUSE and FORS2 spectra superpose almost perfectly in the red wing, emission in the blue wing at 6800 Å is fainter in 2019 than in 2015, as observed in 2016 by Krumpe et al (2017).…”

Section: The Direct Spectrumsupporting

confidence: 83%

“…On the other hand, the fact that the high velocity blue wing was detected in 2000, was absent in 2015, and was back in 2019 suggests that the Balmer lines are formed in a more complex region that may include a disk wind or a polar outflow. A re-brightening (Krumpe et al 2017) would first raise the blue wing of a line that arises in a polar outflow.…”

Section: Discussionmentioning

confidence: 99%

“…Mrk 1018 (redshift z = 0.043) is an active galactic nucleus (AGN) that changed from Seyfert type 1.9 to type 1 between 1979 and 1984 (Cohen et al 1986), then back to type 1.9 in 2015(McElroy et al 2016. After a rapid decline of two magnitudes, the AGN brightness reached a minimum in October 2016, showing thereafter low level variability (Krumpe et al 2017). These changes were explained by variations in the rate of accretion onto a supermassive black hole (Husemann et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018

Hutsemékers

González

Marin

et al. 2020

A&A

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We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad Hβ and Hα emission lines. Both lines can be fit with a single very broad emission line component of full width at half maximum FWHM 7200 km s −1 , with no evidence of the additional 3000 km s −1-wide component that was previously detected. While this is in agreement with line formation in a Keplerian disk, the line profile variability suggests that the broad emission line region is likely more complex. The continuum polarization of Mrk 1018 is low; it is not higher in the current faint state compared to the past bright state, confirming that dust obscuration is not the mechanism at the origin of the change of look. The polarization profile of the Hα line is asymmetric with no rotation of the polarization angle, which possibly reveals line formation in a polar outflow. Alternatively, the polarization profile may be the consequence of a time delay between the direct and the polarized light. Interestingly, the polarization signatures predicted for broad lines emitted around supermassive binary black holes are not observed.

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Section: The Direct Spectrumsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018

Hutsemékers

González

Marin

et al. 2020

A&A

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“…Dunlop et al (2003) note that the radio quiet quasars in their sample also show tidal features that the radio loud quasars lack, indicating that radio observations of CL quasars may provide useful information regarding their dynamical history. A potential link between merger activity and the changing look phenomenon is observed in the CL Quasar, Mrk 1018, which has transitioned between spectral types twice in its observed history (McElroy et al 2016;Krumpe et al 2017). The mechanism for the changes proposed by Kim et al (2018) is that a recoiling SMBH is responsible for perturbing the accretion flow on approximately a 29 year period, corresponding to spectral changes in the quasar.…”

Section: Quasar Host Galaxy Morphology and Dynamicsmentioning

confidence: 99%

Gemini Imaging of the Host Galaxies of Changing-look Quasars

Charlton

Ruan

Haggard

et al. 2019

ApJ

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Changing-look quasars are a newly-discovered class of luminous active galactic nuclei that undergo rapid ( 10 year) transitions between Type 1 and Type 1.9/2, with an associated change in their continuum emission. We characterize the host galaxies of four faded changing-look quasars using broadband optical imaging. We use gri images obtained with the Gemini Multi Object Spectrograph (GMOS) on Gemini North to characterize the surface brightness profiles of the quasar hosts and search for [O III] λ4959, λ5007 emission from spatially extended regions, or voorwerpjes, with the goal of using them to examine past luminosity history. Although we do not detect, voorwerpjes surrounding the four quasar host galaxies, we take advantage of the dim nuclear emission to characterize the colors and morphologies of the host galaxies. Three of the four galaxies show morphological evidence of merger activity or tidal features in their residuals. The three galaxies which are not highly distorted are fit with a single Sérsic profile to characterize their overall surface brightness profiles. The single-Sérsic fits give intermediate Sérsic indices between the n = 1 of disk galaxies and the n = 4 of ellipticals. On a color-magnitude diagram, our changing-look quasar host galaxies reside in the blue cloud, with other AGN host galaxies and star-forming galaxies. On a color-Sérsic index diagram the changing-look quasar hosts reside with other AGN hosts in the "green valley". Our analysis suggests that the hosts of changing-look quasars are predominantly disrupted or merging galaxies that resemble AGN hosts, rather than inactive galaxies.

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“…Those local Seyferts instead exhibit a secular pattern. For example, according to the available data, Mrk 1018 was a Seyfert 1.9 in the year of 1979 and became type 1 in 1984; then the AGN brightness remained constant roughly (as a Seyfert 1), with a small rms (0.15 dex) for at least 10 yr (i.e., 2001-2011 with observations available), and steadily decreased after 2011 (returning to type 1.9 in 2015) by 3-4 magnitudes until a minimum around October 2016, and again gradually got brightening at a low level Krumpe et al 2017); it appears to keep the slow brightening so far, according to the latest observation reporting it as a faint type 1.5 (Hutsemékers et al 2020).…”

Section: Introductionmentioning

confidence: 96%

Local Active Galactic Nuclei with Large Broad-Hα Variability Reside in Red Galaxies

Liu,

Lira,

Yao

et al. 2021

Preprint

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Inspired by our serendipitous discovery of six AGNs with varying broad-Hα fluxes over years out of our searching for intermediate-mass black holes (IMBHs), we conduct a systematic investigation of changing-look (CL) and large-variability AGNs. We collect all the CL AGNs at z < 0.15 and the reverberation mapped AGNs with strongly variable broad Hα, and perform careful decomposition fittings to both their images and spectra. We find two observational facts: (1) The host galaxies of local CL and large-variability AGNs, mainly being Seyferts, are in the red (gas-poor) tail of the general Seyfert galaxy population. (2) In contrast, there is a significant trend that their more luminous counterparts namely CL and extremely variable quasars (CLQs and EVQs) are different: CLQs are generally in blue galaxies; in terms of the diagram of SFR and M ⋆ local CL Seyfert galaxies are located in the green valley, whereas CLQ hosts are in the star-forming main sequence. We propose explanations for those strongly variable Seyferts and quasars, respectively, under the thought that accretion disks broadly depend on nuclear fueling modes. Local large-variability and CL Seyferts are in nuclear famine mode, where cold-gas clumps can be formed stochastically in the fueling flow, and their episodic infall produces sharp peaks in the accretion-rate curve. CLQs and EVQs are in feast fueling mode, which may account for both their preference to blue galaxies and their variability pattern (high-amplitude tail of the continuous distribution). Lastly, we propose a new thinking: to search for IMBHs by optical variability in red galaxies.

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The Close AGN Reference Survey (CARS)

Cited by 21 publications

References 31 publications

Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018

Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018

Gemini Imaging of the Host Galaxies of Changing-look Quasars

Local Active Galactic Nuclei with Large Broad-Hα Variability Reside in Red Galaxies

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