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Changing-look active galactic nuclei (CLAGNs) are characterized by extreme variations in line emission over short time-scales, mostly affecting broad H  |$\beta$| lines. While a few hundred CLAGNs are known, a complete sample of turn-on CLAGNs is still elusive. Here, we present a search for turn-on CLAGNs in a complete sample of galaxies, using archival spectra and recent light curves. We obtained light curves from the Asteroid Terrestrial Impact Last Alert System for 16 232 emission-line galaxies, including both star-forming and active galaxies, at |$z< 0.1$| with spectra from the Six-degree Field Galaxy Survey (6dFGS). We first establish typical variability behaviour for different active galactic nucleus (AGN) types, as recorded between 2001 and 2009, and then select outliers from the bulk behaviour as CLAGN candidates. We obtain new spectra for the candidates and identify 12 new turn-on CLAGNs (appearing broad H  |$\beta$| line) and 19 new turn-off CLAGNs (disappearing broad H  |$\beta$| line). We may have missed AGNs that changed and reverted their state over the 15–20 yr since 6dFGS spectra were taken, and thus our CLAGN rates of 1.7 per cent for turn-on and 9.6 per cent for turn-off are lower limits. The turn-on rate is naturally much lower as the type 1.9/2 sample is dominated by obscured AGNs due to orientation, which is not expected to change. However, the number of turn-on (27) and turn-off (24) CLAGNs we find are similar, suggesting that our parent AGN sample is reasonably complete in our search volume at |$z < 0.1$|⁠. [ABSTRACT FROM AUTHOR]

JWST has discovered a large population of active galactic nuclei (AGN) at high redshift, which are weak in the X-rays. Here we present the NIRSpec spectrum of the most extreme of these objects, GN-28074, an AGN at |$z=2.26$| with prominent hydrogen and He  i  broad lines, and with the highest limit on the bolometric to X-ray luminosity ratio among all spectroscopically confirmed AGN in GOODS. This source is also characterized by a mid-IR excess, likely associated with the AGN torus' hot dust. The high bolometric luminosity and moderate redshift of this AGN allow us to explore its properties more in depth relative to other JWST -discovered AGN. The NIRSpec spectrum reveals prominent, slightly blueshifted absorption of H |$\alpha$|⁠ , H |$\beta$|⁠ , and He  i   |$\lambda$| 10830. The Balmer absorption lines require gas with densities of |$n_{\rm H}\gt 10^8~{\rm cm}^{-3}$|⁠ , consistent with clouds in the broad-line region (BLR). This finding suggests that part of the X-ray weakness is due to high (Compton-thick) X-ray absorption by clouds in the BLR, or in its outer regions. GN-28074 is also extremely radio-weak. The radio weakness can also be explained in terms of absorption, as the inferred density of the BLR clouds makes them attenuate the radio emission through free–free absorption. Alternatively, the nuclear magnetic field may be underdeveloped, resulting both in intrinsically weak radio emission and lack of hot corona, hence intrinsic X-ray weakness. Finally, we show that recently proposed scenarios, invoking hyper-dense outflows or Raman scattering to explain the broad H |$\alpha$|⁠ , are ruled out. [ABSTRACT FROM AUTHOR]

We derive the nitrogen and oxygen abundances in the narrow line regions (NLRs) of a sample of 38 local (⁠|$z \: \lt \: 0.4$|⁠) Seyfert 2 nuclei. For that, we consider narrow optical emission line intensities and direct estimates of the electron temperatures (⁠|$T_{\rm e}$| -method). We obtain a new theoretical expression for the nitrogen ionization correction factor [ICF(⁠|$\rm N^{+}$|⁠)] for NLRs. Applying this new ICF, we unexpectedly find that NLRs and disc H  ii regions exhibit similar ICF distributions. We find nitrogen abundances in the range |$7.6 \: \lt \: \rm 12+log(N/H) \: \lt \: 8.6$| (mean value |$8.06\pm 0.22$|⁠) or |$\rm 0.4 \: \lt \: (N/N_{\odot }) \: \lt 4.7$|⁠ , in the metallicity regime |$8.3 \: \lt \: \rm 12+log(O/H) \: \lt \: 9.0$|⁠. Our results indicate that the dispersion in N/H abundance for a fixed O/H value in AGNs of |$\sim 0.2$| dex agrees with that for disc H  ii regions with similar metallicity. We show that Seyfert 2 nuclei follow a similar (N/O)–(O/H) relation to the one followed by star-forming objects. Finally, we find that active galaxies called as ..nitrogen-loud.. observed at very high redshift (⁠|$z \: \gt \: 5$|⁠) show N/O values in consonance with those derived for local NLRs. This result indicates that the main star-formation event is completed in the early evolution stages of active galaxies. [ABSTRACT FROM AUTHOR]

We explore the relations between the gas-phase metallicity radial profiles (few hundred inner parsec) and multiple galaxy properties for 15 Seyfert galaxies from the active galactic nuclei integral field spectroscopy sample using optical integral field unit observations from Gemini Multi-Object Spectrograph (GMOS) and Multi Unit Spectroscopic Explorer (MUSE) processed archival data. The data were selected at |$z \lesssim 0.013$| within black hole mass range |$\left[6\lt \log \left(M_{\rm BH}/{\rm M_\odot } \right)\lt 9\right]$| with moderate 14–150-keV X-ray luminosities |$\left[42\, \lesssim \, \log L_X (\rm erg\, s^{-1})\, \lesssim \, 44\right]$|⁠. We estimated the gas-phase metallicity using the strong-line methods and found mean values for the oxygen-dependent (⁠|$Z \sim 0.75\, \mathrm{Z}_\odot$|⁠) and nitrogen-dependent (⁠|$Z \sim 1.14\, \mathrm{Z}_\odot$|⁠) calibrations. These estimates show excellent agreement with |$\Delta Z \approx 0.19$| and 0.18 dex between the mean values from the two strong-line calibrations for GMOS and MUSE, respectively, consistent with the order of metallicity uncertainty via the strong-line methods. We contend that our findings align with a scenario wherein local Seyferts have undergone seamless gas accretion histories, resulting in positive metallicity profiles over an extended period of time, thereby providing insights into galaxy evolution and the chemical enrichment or depletion of the universe. Additionally, we argue that metal-poor gas inflow from the local interstellar medium and accreted through the circumgalactic medium on to the galaxy systems regulates the star formation processes by diluting their central metallicity and inverting their gas-phase metallicity radial gradients, producing a more prominent anticorrelation between gas-phase metallicity and Eddington ratio. [ABSTRACT FROM AUTHOR]

In the era of massive photometric surveys, we explore several approaches to estimate the masses of supermassive black holes (SMBHs) in active galactic nuclei (AGNs) from optical ground-based imaging, in each case comparing to the independent SMBH mass measurement obtained from spectroscopic data. We select a case-study sample of 28 type 1 AGN hosted by nearby galaxies from the Galaxy And Mass Assembly (GAMA) survey. We perform multicomponent spectral decomposition, extract the AGN component, and calculate the SMBH mass from the broad H |$\alpha$| emission line width and luminosity. The photometric g and i band data is decomposed into AGN+spheroid(+disc)(+bar) components with careful surface brightness fitting. From these, the SMBH mass is estimated using its relation with the spheroid Sérsic index or effective radius (both used for the first time on ground-based optical imaging of AGN); and the more widely used scaling relations based on bulge or galaxy stellar mass. We find no correlation between the H |$\alpha$| -derived SMBH masses and those based on the spheroid Sérsic index or effective radius, despite these being the most direct methods involving only one scaling relation. The bulge or galaxy stellar mass based methods both yield significant correlations, although with considerable scatter and, in the latter case, a systematic offset. We provide possible explanations for this and discuss the requirements, advantages, and drawbacks of each method. These considerations will be useful to optimize strategies for upcoming high quality ground-based and space-borne sky surveys to estimate SMBH masses in large numbers of AGN. [ABSTRACT FROM AUTHOR]

A well-known calibrator source in radio astronomy, 3C 286 (⁠|$z=0.85$|⁠), is a compact steep-spectrum (CSS) radio source and spectroscopically classified as a narrow-line Seyfert 1 (NLS1) galaxy. It is also known for its damped Ly |$\alpha$| system from an intervening galaxy at |$z=0.692$| detected in both ultraviolet (UV) and radio spectra. In addition, despite being a misaligned active galactic nuclei (AGN), 3C 286 is also detected in |$\gamma$| -rays by Fermi. Thus, this unique object combines the characteristics of CSS sources, NLS1 galaxies, and |$\gamma$| -ray emitters with misaligned jets, providing an excellent laboratory for extending our knowledge of AGN disc–jet coupling. Despite its significance, 3C 286 has been rarely observed in X-rays. In this study, we present our deep XMM–Newton and Chandra observations of 3C 286. The results reveal that the X-ray spectrum can be well-described by models including an intervening absorber with redshift and column density consistent with previous UV and radio observations. The most important finding is that the spectrum cannot be described by a single power law, but a soft excess is required which is parametrized by a blackbody. Furthermore, we find evidence suggesting the presence of off-nuclear X-ray emission at a radius that corresponds to the location of the radio lobes. While further theoretical work is still needed, our findings offer new clues to understand the specific mechanism for |$\gamma$| -ray emission from this unique object. [ABSTRACT FROM AUTHOR]

Polar dust has been discovered in a number of local active galactic nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST /MIRI study aimed at imaging polar dust by zooming on to the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionized by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to |$r\approx 100 \, \rm pc$|⁠. We estimate the emitting dust has a temperature of |$\sim 120\, \rm K$|⁠. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies. [ABSTRACT FROM AUTHOR]

We report on the discovery of one of the most extreme cases of high-frequency radio variability ever measured in active galactic nuclei (AGNs), observed on time-scales of days and exhibiting variability amplitudes of 3–4 orders of magnitude. These sources, all radio-weak narrow-line Seyfert 1 (NLS1) galaxies, were discovered some years ago at Aalto University Metsähovi Radio Observatory (MRO) based on recurring flaring at 37 GHz, strongly indicating the presence of relativistic jets. In subsequent observations with the Karl G. Jansky Very Large Array (JVLA) at 1.6, 5.2, and 9.0 GHz no signs of jets were seen. To determine the cause of their extraordinary behaviour, we observed them with the JVLA at 10, 15, 22, 33, and 45 GHz, and with the Very Long Baseline Array (VLBA) at 15 GHz. These observations were complemented with single-dish monitoring at 37 GHz at MRO, and at 15 GHz at Owens Valley Radio Observatory (OVRO). Intriguingly, all but one source either have a steep radio spectrum up to 45 GHz, or were not detected at all. Based on the 37 GHz data, the time-scales of the radio flares are a few days, and the derived variability brightness temperatures and variability Doppler factors are comparable to those seen in blazars. We discuss alternative explanations for their extreme behaviour, but so far no definite conclusions can be made. These sources exhibit radio variability at a level rarely, if ever, seen in AGN. They might represent a new type of jetted AGN, or a new variability phenomenon, and thus deserve our continued attention. [ABSTRACT FROM AUTHOR]

Despite the evidence that supermassive black holes (SMBHs) co-evolve with their host galaxy, and that most of the growth of these SMBHs occurs via merger-free processes, the underlying mechanisms which drive this secular co-evolution are poorly understood. We investigate the role that both strong and weak large-scale galactic bars play in mediating this relationship. Using 48 871 disc galaxies in a volume-limited sample from Galaxy Zoo DESI, we analyse the active galactic nucleus (AGN) fraction in strongly barred, weakly barred, and unbarred galaxies up to |$z = 0.1$| over a range of stellar masses and colours. After controlling for stellar mass and colour, we find that the optically selected AGN fraction is |$31.6 \pm 0.9$| per cent in strongly barred galaxies, |$23.3 \pm 0.8$| per cent in weakly barred galaxies, and |$14.2 \pm 0.6$| per cent in unbarred disc galaxies. These are highly statistically robust results, strengthening the tantalizing results in earlier works. Strongly barred galaxies have a higher fraction of AGNs than weakly barred galaxies, which in turn have a higher fraction than unbarred galaxies. Thus, while bars are not required in order to grow an SMBH in a disc galaxy, large-scale galactic bars appear to facilitate AGN fuelling, and the presence of a strong bar makes a disc galaxy more than twice as likely to host an AGN than an unbarred galaxy at all galaxy stellar masses and colours. [ABSTRACT FROM AUTHOR]

We present a comprehensive analysis of approximately 15 years (2006–2021) of X-ray observations of UGC 6728, a low-mass bare AGN, for the first time. Our study encompasses both spectral and temporal aspects of this source. The spectral properties of this source are studied using various phenomenological and physical models. We conclude that (a) the observed variability in X-ray luminosity is not attributed to the hydrogen column density (N H) as UGC 6728 exhibits a bare nucleus, implying a negligible N H contribution along the line of sight, and (b) the spectral slope in the X-ray band demonstrates a systematic variation over time, indicating a transition from a relatively hard state to a comparatively soft state. We propose that the underlying accretion dynamics around the central object account for this behaviour. By performing X-ray spectral fitting, we estimate the mass of the central supermassive black hole (SMBH) in UGC 6728 to be |$M_{\rm BH}=(7.13\pm 1.23)\times 10^5$|  M |$_\odot$|⁠. Based on our spectral and temporal analysis, we suggest that UGC 6728 lacks a prominent Compton hump or exhibits a very subtle hump that remains undetectable in our analysis. Furthermore, the high-energy X-ray photons in this source are likely to originate from the low-energy X-ray photons through inverse Compton scattering in a Compton cloud, highlighting a connection between the emission in two energy ranges. We noticed a strong soft excess component in the initial part of our observations, which was later reduced substantially. This variation of soft excess is explained in view of accretion dynamics. [ABSTRACT FROM AUTHOR]

This study investigates the properties of two gas structures of X-ray selected active galactic nuclei (AGNs), that is, dusty and dust-free gas components, by separating them with the line-of-sight dust extinction (⁠|$A_V$|⁠) and the neutral gas column density (⁠|$N_{\mathrm{H}}$|⁠). The typical column density of the dusty and dust-free gas differs depending on the Seyfert type, indicating that both structures have anisotropic column density distributions. The number of targets with the dusty gas column density (⁠|$N_{\mathrm{H,d}}$|⁠) of |$\log N_{\mathrm{H,d}}\ [\mathrm{cm^{-2}}]\gt 23$| is much smaller than that with the same column density of the dust-free gas. This result indicates that the optically thick part of the dusty gas structure is very thin. There are very few targets with a larger Eddington ratio (⁠|$f_{\mathrm{Edd}}$|⁠) than the effective Eddington limit of the dusty gas and the covering factor of the dusty gas with |$22\le \log N_{\mathrm{H,d}}\ [\mathrm{cm^{-2}}]\lt 24$| exhibits a clear drop at the effective Eddington limit. These results support the scenario wherein the covering factor of the dusty torus decreases in a high Eddington ratio owing to the radiation-driven dusty gas outflow. The covering factor of the dust-free gas with the column density (⁠|$N_{\mathrm{H,df}}$|⁠) of |$22\le \log N_{\mathrm{H,df}}\ [\mathrm{cm^{-2}}]\lt 24$| similarly exhibits the decrease in high Eddington ratio, although it may be owing to the dust-free gas outflow driven by certain other mechanisms than the radiation pressure. Finally, we propose an updated picture of the AGN gas structure based on our results and the literature. [ABSTRACT FROM AUTHOR]

The detection of a high-velocity (∼0.3 c) inflow of highly ionized matter during an extended XMM–Newton observation of the luminous Seyfert galaxy PG1211+143 in 2014 provided the first direct evidence of a short-lived accretion event, and an explanation for the powerful winds (UFOs) now recognized as a common property of many luminous Seyfert galaxies. Although the ultra-fast inflow observed at a redshift of 0.483 was detected in only one of seven spacecraft orbits, weaker (lower column) but more persistent absorption is seen at a redshift of 0.123 in the high-exposure soft X-ray (RGS) spectra summed over all seven individual spacecraft orbits. Similar stacking of the higher energy (pn camera) spectra reveals underlying absorption at a redshift of 0.148. Interpreted, conventionally, as a Doppler redshift, the RGS observation indicates a line-of-sight inflow velocity v ∼ 0.038 c and (free-fall) radial location at 1400  Rg , with the higher redshift and ionization in pn camera spectra perhaps detecting that inflow closer to the black hole. A very different explanation would be absorption in matter subject to the strong gravity close to the SMBH, an interpretation supported by the launch of a new UFO in the final spacecraft orbit. [ABSTRACT FROM AUTHOR]

In terms of the variable nature of normal active galaxy nuclei (AGN) and luminous quasars, a so-called flux variation gradient (FVG) method has been widely utilized to estimate the underlying non-variable host galaxy fluxes. The FVG method assumes an invariable AGN color, but this assumption has been questioned by the intrinsic color variation of quasars and local Seyfert galaxies. Here, using an up-to-date thermal fluctuation model to simulate multi-wavelength AGN variability, we theoretically demonstrate that the FVG method generally overestimates the host galaxy flux; that is, it is more significant for brighter AGN/quasars. Furthermore, we observationally confirm that the FVG method indeed overestimates the host galaxy flux by comparing it to that estimated through other independent methods. We thus caution that applying the FVG method should be performed carefully in the era of time-domain astronomy. [ABSTRACT FROM AUTHOR]

Spectral energy distribution (SED) fitting is one of the most commonly used techniques to study the dust properties in active galactic nuclei (AGN). Works implementing this technique commonly use radiative transfer models that assume a variety of dust properties. Despite the key role of this aspect, limited effort has been put forward to explore the chemical composition, the role of different optical properties, and the grain size distribution of dust, all of which can have a substantial impact on the theoretical radiative transfer calculations. In this work, we explore the role of the dust chemical composition in the AGN dusty torus through SED fitting to Spitzer /IRS spectra of a sample of 49 nearby AGN with silicate features in emission. We implement a mineralogy model including the popular astronomical silicates and a set of oxides and amorphous silicates with different grain sizes. Wefind that best fits use principally porous alumina, periclase, and olivine. In terms of mass fractions, |$\sim 99~{{\ \rm per\ cent}}$| of the dust is composed of dust grains of size |$\rm {0.1 \, \mu m}$|⁠ , with a |$\lt 1~{{\ \rm per\ cent}}$| contribution from |$\rm {3 \, \mu m}$| grains. Moreover, the astronomical silicates have a very low occurrence in the best fits, suggesting that they are not the most suited dust species to reproduce the silicate features in our sample. [ABSTRACT FROM AUTHOR]

Sizes of narrow emission line regions (NLRs) of active galactic nuclei (AGNs) could be estimated by [O  iii ] line luminosity L O3 through the known R NLRs− L O3 empirical relations. Unfortunately, it is not convenient to test the R NLRs− L O3 empirical relations through structure properties of spatially resolved NLRs of large samples of AGNs. In this manuscript, a method is proposed to test the |$R_{\mathrm{ NLRs}}\!\!-\!\!L_{\mathrm{ O3}}^{\sim 0.25}$| empirical relations for AGN NLRs through Sloan Digital Sky Survey (SDSS) Type-2 AGNs having few orientation effects on NLR sizes expected by the AGN unified model, after considering sizes R fib of SDSS fibre-covered regions. Comparing R fib and R NLRs estimated by L O3, Type-2 AGNs with R fib > R NLRs (Sample-II) and with R fib < R NLRs (Sample-I) should have different physical properties of NLRs. Accepting electron density gradients in AGN NLRs, statistically higher electron densities (traced by lower flux ratio R S2 of [S  ii ] λ6717 Å to [S  ii ] λ6731 Å) could be expected for the Type-2 AGNs in the Sample-I. Then, through the collected 1062 SDSS Type-2 AGNs in the Sample-I and 3658 SDSS Type-2 AGNs in the Sample-II, statistically lower R S2 for the Type-2 AGNs in the Sample-I can be confirmed with confidence level higher than 5σ, even after considering necessary effects. Therefore, the results in this manuscript can provide strong clues to support that the reported |$R_{\mathrm{ NLRs}}~\propto ~L_{\mathrm{ O3}}^{0.25}$| empirical relation is preferred to estimate NLR sizes of SDSS AGNs through SDSS fibre spectroscopic results, and also to support the commonly expected electron density gradients in AGN NLRs. [ABSTRACT FROM AUTHOR]

The fourth-DR3 version (4FGL-DR3) of the Fermi -LAT catalogue of γ-ray sources contains ∼1000 objects at a galactic latitude | b | > 10° that are not identified with an optical counterpart. We performed a systematic study of these sources, focusing on 190 objects that have a unique X-ray counterpart in the available Swift /XRT observations. Optical counterparts were then selected, and optical spectra were found in the literature for 33 sources. We found that 21 could be classified as BL Lac objects. Among these, we were able to provide the redshift for eight of them, while for two others we established a lower limit to the redshift by detecting intervening absorption. The other 12 objects display optical spectra with prominent emission lines (0.036 <  z  < 1.65). These spectra are characterized by both broad and narrow emission lines, with the exception of three sources. One of these displays only broad emission lines, while the other two exclusively exhibit narrow lines. On the basis of the radio/optical flux ratio, all BL Lac objects in this study are radio-loud. Four sources out of the 12 with prominent emission lines can be classified as radio-loud, while at least five of the 12 sources with prominent lines are radio-quiet. This is somewhat unexpected, given the radio-loudness distribution of 4FGL-associated blazars. [ABSTRACT FROM AUTHOR]

NGC 4395 is a dwarf type 1 Seyfert galaxy with a possible intermediate-mass black hole of several |$\rm {10^4}$| solar masses in its centre. As a well-studied object, its broad-line region size has been measured via H  |$\rm {\alpha }$| time lag in numerous spectroscopic reverberation mapping (SRM) and narrow-band photometric reverberation mapping (PRM) campaigns. Here, we present its H  |$\rm {\alpha }$| time lag measurement using broad-band photometric data, with the application of our newly developed ICCF-Cut (Interpolation and Cross-Correlation Function - Cut) method as well as the javelin (Just Another Vehicle for Estimating Lags In Nuclei) and χ2 methods. Utilizing the minute-cadence multiband light curves obtained from the |$\rm {2}$| -m Faulkes Telescope North and |$\rm {10.4}$| -m Gran Telescopio Canarias telescopes in recent works, we measured its H  |$\rm {\alpha }$| lag as approximately 40–90 min from broad-band PRM. With the H  |$\rm {\alpha }$| emission line velocity dispersion, we calculated its central black hole mass as |$M_{\rm BH} = (8\pm 4) \times 10^3\ \mathrm{ M}_{\rm \odot }$|⁠. These results are comparable with previous results obtained by narrow-band PRM and SRM, providing further support to an intermediate-mass black hole in NGC 4395. In addition, our study also validates the ICCF-Cut as an effective method for broad-band PRM, which holds the potential for widespread application in the era of large multi-epoch, high-cadence photometric surveys. [ABSTRACT FROM AUTHOR]

We present the results of a search for extended emission-line regions (EELRs) ionized by extant or recently faded active galactic nuclei (AGNs), using [O III] narrow-band imaging and spectroscopic follow-up. The sample includes 198 galaxies in 92 strongly interacting or merging galaxy systems in the range of z  = 0.009–0.0285. Among these, three systems have EELRs extended beyond 10 kpc in projection from the nucleus detected in previous studies. We identify a single new distant emission region, projected 35 kpc from UGC 5941. Our optical spectrum does not detect He II, but its strong-line ratios put this in the same class as securely characterized EELR clouds. The nucleus of UGC 5941 is dominated by recent star formation, preventing detection of any weak ongoing AGN. Overall counts of distant EELRs in this and the previous TELPERION samples give incidence 2–5 per cent depending on galaxy and AGN selection, 20–50 times higher than the Galaxy Zoo EELR survey with its higher surface-brightness threshold and much larger input sample. AGNs in interacting and merging systems have an increased detection rate of 12 ± 6 per cent, while none are detected around non-interacting AGNs. Some of these AGNs are at luminosity low enough to require additional X-ray or far-infrared information to tell whether the EELR ionization level suggests long-term fading. [ABSTRACT FROM AUTHOR]

The soft excess in active galactic nuclei (AGNs) may arise through a combination of relativistic reflection and the effects of a warm corona at the surface of the accretion disc. Detailed examination of the soft excess can therefore constrain models of the transport and dissipation of accretion energy. Here, we analyse 34 XMM–Newton observations from 14 type 1 AGNs with the reXcor spectral model that self-consistently combines emission from a warm corona with relativistic reflection assuming a lamppost corona. The model divides accretion energy between the disc, the warm corona, and the lamppost. The XMM–Newton observations span a factor of 188 in Eddington ratio (λobs) and 350 in black hole mass, and we find that a warm corona is a significant contributor to the soft excess for 13 of the 14 AGNs with a mean warm corona heating fraction of 0.51. The reXcor fits reveal that the fraction of accretion energy dissipated in the lamppost is anticorrelated with λobs. In contrast, the relationship between λobs and both the optical depth and the heating fraction of the warm corona appears to transition from an anticorrelation to a correlation at λobs,t ≈ 0.15. Therefore, at least one other physical process in addition to the accretion rate is needed to explain the evolution of the warm corona. Overall, we find that a warm corona appears to be a crucial depository of accretion energy in AGNs across a broad range of λobs and black hole mass. [ABSTRACT FROM AUTHOR]

Near IR spectroscopic reverberation of Active Galactic Nuclei (AGN) potentially allows the infrared (IR) broad line region (BLR) to be reverberated alongside the disc and dust continua, while the spectra can also reveal details of dust astro-chemistry. Here, we describe results of a short pilot study (17 near-IR spectra over a 183 d period) for Mrk 509. The spectra give a luminosity-weighted dust radius of 〈 R d,lum〉 = 186 ± 4 light-days for blackbody (large grain dust), consistent with previous (photometric) reverberation campaigns, whereas carbon and silicate dust give much larger radii. We develop a method of calibrating spectral data in objects where the narrow lines are extended beyond the slit width. We demonstrate this by showing our resultant photometric band light curves are consistent with previous results, with a hot dust lag at >40 d in the K band, clearly different from the accretion disc response at <20 d in the z band. We place this limit of 40 d by demonstrating clearly that the modest variability that we do detect in the H and K band does not reverberate on time-scales of less than 40 d. We also extract the Pa β line light curve, and find a lag which is consistent with the optical BLR H β line of ∼70–90 d. This is important as direct imaging of the near-IR BLR is now possible in a few objects, so we need to understand its relation to the better studied optical BLR. [ABSTRACT FROM AUTHOR]

The article titled "Correction to: Characterizing X-ray, UV, and optical variability in NGC 6814 using high-cadence Swift observations from a 2022 monitoring campaign" published in the Monthly Notices of the Royal Astronomical Society discusses a correction to a previous study on NGC 6814. The authors discovered that an outdated Calibration Database (CALDB) version was used in the original study, leading to significantly larger UV flux densities. The updated results show that the intrinsic AGN variability spectrum aligns with a standard accretion disc, except in the U band. The authors also discuss the inter-band continuum lags and suggest that a significant contribution from diffuse continuum emission in NGC 6814 may explain the observed discrepancies. The corrected data is publicly available through the NASA HEASARC Archive and Swift observatory websites. [Extracted from the article]

Supermassive black holes require a reservoir of cold gas at the centre of their host galaxy in order to accrete and shine as active galactic nuclei (AGN). Major mergers have the ability to drive gas rapidly inwards, but observations trying to link mergers with AGN have found mixed results due to the difficulty of consistently identifying galaxy mergers in surveys. This study applies deep learning to this problem, using convolutional neural networks trained to identify simulated post-merger galaxies from survey-realistic imaging. This provides a fast and repeatable alternative to human visual inspection. Using this tool, we examine a sample of ∼8500 Seyfert 2 galaxies (⁠|$L[\mathrm{O\, {\small III}}] \sim 10^{38.5 - 42}$|  erg s−1) at z < 0.3 in the Sloan Digital Sky Survey and find a merger fraction of |$2.19_{-0.17}^{+0.21}$|  per cent compared with inactive control galaxies, in which we find a merger fraction of |$2.96_{-0.20}^{+0.26}$|  per cent, indicating an overall lack of mergers among AGN hosts compared with controls. However, matching the controls to the AGN hosts in stellar mass and star formation rate reveals that AGN hosts in the star-forming blue cloud exhibit a ∼2 × merger enhancement over controls, while those in the quiescent red sequence have significantly lower relative merger fractions, leading to the observed overall deficit due to the differing M *–SFR distributions. We conclude that while mergers are not the dominant trigger of all low-luminosity, obscured AGN activity in the nearby Universe, they are more important to AGN fuelling in galaxies with higher cold gas mass fractions as traced through star formation. [ABSTRACT FROM AUTHOR]

We present a long-term X-ray study of a nearby Active Galactic Nucleus Mrk 6, utilizing observations from XMM–Newton, Suzaku, Swift , and NuSTAR observatories, spanning 22 years from 2001 to 2022. From timing analysis, we estimated variance, normalized variance, and fractional rms amplitude in different energy bands.The temporal study shows fractional rms amplitude (F var) below 10 per cent for the shorter time-scale (∼60 ks) and above 20 per cent for the longer time-scale (∼weeks). A complex correlation is observed between the soft (0.5–3.0 keV) and hard (3.0–10.0 keV) X-ray bands of different epochs of observations. This result prompts a detailed investigation through spectral analysis, employing various phenomenological and physical models on the X-ray spectra. Our analysis reveals a heterogeneous structure of the obscuring material surrounding Mrk 6. A partially ionized absorber exhibits a rapid change in location and extends up to the narrow-line regions or torus. In contrast, another component, located far from the central engine, remained relatively stable. During the observation period, the source luminosity in the 3.0–10.0 keV range varies between (3–15) × 1042 erg s−1. [ABSTRACT FROM AUTHOR]

Variability studies of active galactic nuclei are a powerful diagnostic tool in understanding the physical processes occurring in disc-jet regions, unresolved by direct imaging with currently available techniques. Here, we report the first attempt to systematically characterize intra-night optical variability (INOV) for a sample of seven apparently radio-quiet narrow-line Seyfert 1 galaxies (RQNLSy1s) that had shown recurring flaring at 37 GHz in the radio observations at Metsähovi Radio Observatory, indicating the presence of relativistic jets in them, but no evidence for relativistic jets in the recent radio observations of Karl G. Jansky Very Large Array at 1.6, 5.2, and 9.0 GHz. We have conducted a total of 28 intra-night sessions, each lasting ≥3 h for this sample, resulting in an INOV duty cycle (⁠|$\overline{\mathrm{ DC}} ~\sim$| 20 per cent) similar to that reported for γ-ray-NLSy1s (DC ∼ 25 per cent–30 per cent), that display blazar-like INOV. This in turn infers the presence of relativistic jet in our sample sources. Thus, it appears that even lower mass (M BH ∼ 106 M⊙) RQNLSy1 galaxies can maintain blazar-like activities. However, we note that the magnetic reconnection in the magnetosphere of the black hole can also be a viable mechanism to give rise to the INOV from these sources. [ABSTRACT FROM AUTHOR]

X-ray properties of active galactic nuclei (AGNs) depend on their underlying physical parameters, particularly the accretion rate. We identified eight reverberation-mapped AGNs with some of the largest known accretion rates without high-quality X-ray data. We obtained new Chandra ACIS-S X-ray observations and nearly simultaneous optical spectrophotometry to investigate the properties of these AGNs with extreme super-Eddington accreting massive black holes (SEAMBHs). We combined our new X-ray measurements with those of other reverberation-mapped AGNs, which have the best-determined masses and accretion rates. The trend of the steepening of the spectral slope between X-ray and optical-UV, αox, with increasing optical-UV luminosity, |$L_{\rm 2500{\mathring{\rm A}}}$|⁠ , holds true for even the most extreme SEAMBHs. One of our new SEAMBHs appears X-ray-weak for its luminosity, perhaps due to absorption associated with orientation effects involving a slim disc thought to be present in highly accreting systems. The correlation of the |$\rm 2\!-\!8~ keV$| X-ray photon index with the accretion rate also holds for the extreme SEAMBHs, which show some of the largest photon indices reported for AGNs. [ABSTRACT FROM AUTHOR]

Spatially resolved MaNGA's optical spectra of 1072 present-day lenticular (S0) galaxies, dimensionally reduced from a principal component analysis (PCA), are used to determine their radial activity structure shaped by any possible nebular ionization source. Activity profiles within |$1.5\,$| R e are examined in tandem with the mass, age, ellipticity, and kinematics of the stars, as well as environmental density. Among the results of this comparison, we find that the sign of the radial activity gradient of S0s is tightly related to their PCA classification, BPT designation, and star formation status. PCA-passive lenticulars often show low-level, flat activity profiles, although there is also a significant number of systems with positive gradients, while their less common active counterparts generally have negative gradients, usually associated with high SSFRs and, sometimes, moderate Seyfert emission. A fraction of the latter also shows radial activity profiles with positive gradients, which become more abundant with increasing stellar mass regardless of environmental density. Our analysis also reveals that the subset of active S0s with negative gradients experiences at all galactocentric radii a systematic reduction in its median activity level with stellar mass, consistent with expectations for main-sequence galaxies. In contrast, passive S0s with positive gradients show the opposite behaviour. Furthermore, systems whose activity is dominated by star formation are structurally rounder than the rest of S0s, while those classified as Seyfert exhibit higher rotational support. The possibility that negative and positive activity gradients in S0s may result from rejuvenation by two distinct types of minor mergers is raised. [ABSTRACT FROM AUTHOR]

In the Hubble Space Telescope /Cosmic Origins Spectrograph spectrum of the Seyfert 1 galaxy 2MASX J14292507+4518318, we have identified a narrow absorption line outflow system with a velocity of −151 km s−1. This outflow exhibits absorption troughs from the resonance states of ions like C  iv , N  v , S  iv , and Si  ii , as well as excited states from C  ii * and Si  ii *. Our investigation of the outflow involved measuring ionic column densities and conducting photoionization analysis. These allow the total column density of the outflow to be estimated as log  N H = 19.84 cm−2, its ionization parameter to be log  U H = −2.0, and its electron number density to be log  n e = 2.75 cm−3. These measurements enabled us to determine the mass-loss rate and the kinetic luminosity of the outflow system to be |$\dot{M}$|  = 0.22  |$\mathrm{ M}_{\odot } \, \mathrm{ yr}^{-1}$| and |$\log \dot{E_{\mathrm{ K}}}$|  = 39.3 erg s−1, respectively. We have also measured the location of the outflow system to be at ∼275 pc from the central source. This outflow does not contribute to the active galactic nucleus (AGN) feedback processes due to the low ratio of the outflow's kinetic luminosity to the AGN's Eddington luminosity (⁠|$\dot{E_{\mathrm{ K}}}/{L_{\mathrm{ Edd}}}\approx 0.00025 {{\, \rm per\, cent}}$|⁠). This outflow is remarkably similar to the two bipolar lobe outflows observed in the Milky Way by XMM–Newton and Chandra. [ABSTRACT FROM AUTHOR]

We analyse the validity of optical diagnostic diagrams relying on emission-lines ratios and in the context of classifying Active Galactic Nuclei (AGNs) according to the cosmic metallicity evolution in the redshift range |$0 \le z \le 11.2$|⁠. In this regard, we fit the results of chemical evolution models (CEMs) to the radial gradients of the N/O abundances ratio derived through direct estimates of electron temperatures (T e-method) in a sample of four local spiral galaxies. This approach allows us to select representative CEMs and extrapolate the radial gradients to the nuclear regions of the galaxies in our sample, inferring in this way the central N/O and O/H abundances. The nuclear abundance predictions for theoretical galaxies from the selected CEMs, at distinct evolutionary stages, are used as input parameters in AGN photoionization models built with the Cloudy code. We found that standard BPT diagnostic diagrams are able to classify AGNs with oxygen abundances |$\rm 12+\log (O/H) \gtrsim 8.0$| [ |$(Z/Z_{\odot }) \gtrsim 0.2$| ] at redshift |$z \lesssim 4$|⁠. On the other hand, the He  ii λ4685/Hβ versus [N  ii ]λ6584/Hα diagram produces a reliable AGN classification independent of the evolutionary stage of these objects. [ABSTRACT FROM AUTHOR]

Narrow-line Seyfert 1 (NLSy1) galaxies are an enigmatic class of active galactic nuclei (AGN) that exhibit peculiar multiwavelength properties across the electromagnetic spectrum. For example, these sources have allowed us to explore the innermost regions of the central engine of AGN using X-ray observations and have also provided clues about the origin of relativistic jets considering radio and gamma-ray bands. Keeping in mind the ongoing and upcoming wide-field, multifrequency sky surveys, we present a new catalogue of NLSy1 galaxies. This was done by carrying out a detailed decomposition of >2 million optical spectra of quasars and galaxies from the Sloan Digital Sky Survey Data Release 17 (SDSS-DR17) using the publicly available software 'Bayesian AGN Decomposition Analysis for SDSS Spectra'. The catalogue contains 22656 NLSy1 galaxies which is more than twice the size of the previously identified NLSy1s based on SDSS-DR12. As a corollary, we also release a new catalogue of 52273 broad-line Seyfert 1 (BLSy1) galaxies. The estimated optical spectral parameters and derived quantities confirm the previously known finding of NLSy1 galaxies being AGN powered by highly accreting, low-mass black holes. We conclude that this enlarged sample of NLSy1 and BLSy1 galaxies will enable us to explore the low-luminosity end of the AGN population by effectively utilizing the sensitive, high-quality observations delivered by ongoing/upcoming wide-field sky surveys. The catalogue has been made public at https://www.ucm.es/blazars/seyfert. [ABSTRACT FROM AUTHOR]

We present the first results of a high-cadence Swift monitoring campaign (3–4 visits per day for 75 d) of the type 1.5 Seyfert galaxy NGC 6814 characterizing its variability throughout the X-ray and ultraviolet (UV)/optical wavebands. Structure function analysis reveals an X-ray power law (⁠|$\alpha =0.5^{+0.2}_{-0.1}$|⁠) that is significantly flatter than the one measured in the UV/optical bands (〈α〉 ≈ 1.5), suggesting different physical mechanisms driving the observed variability in each emission region. The structure function break-time is consistent across the UV/optical bands (〈τ〉 ≈ 2.3 d), suggesting a very compact emission region in the disc. Correlated short time-scale variability measured through cross-correlation analysis finds a lag–wavelength spectrum that is inconsistent with a standard disc reprocessing scenario (τ ∝ λ4/3) due to significant flattening in the optical wavebands. Flux–flux analysis finds an extremely blue active galactic nucleus (AGN) spectral component (F ν ∝ λ−0.85) that does not follow a standard accretion disc profile (F ν ∝ λ−1/3). While extreme outer disc truncation (R out = 202 ± 5 rg) at a standard accretion rate (⁠|$\dot{m}_{\mathrm{Edd}}=0.0255\pm 0.0006$|⁠) may explain the shape of the AGN spectral component, the lag–wavelength spectrum requires more modest truncation (⁠|$R_{\mathrm{out}}=1382^{+398}_{-404}\,r_g$|⁠) at an extreme accretion rate (⁠|$\dot{m}_{\mathrm{Edd}}=1.3^{+2.1}_{-0.9}$|⁠). No combination of parameters can simultaneously explain both results in a self-consistent way. Our results point towards the possibility of a non-standard disc geometry in NGC 6814. [ABSTRACT FROM AUTHOR]

We study the connection between the variations in the far-ultraviolet (FUV), near-ultraviolet (NUV), and X-ray band emission from NGC 4051 using 4 d long AstroSat observations performed during 5–9 June 2016. NGC 4051 showed rapid variability in all three bands with the strongest variability amplitude in the X-ray band (⁠|$F_{\mathrm{ var}} \sim 37~{{\ \rm per\ cent}}$|⁠) and much weaker variability in the UV bands (⁠|$F_{\mathrm{ var}} \sim 3{\!-\!}5~{{\ \rm per\ cent}}$|⁠). Cross-correlation analysis performed using interpolated cross-correlation functions and discrete cross-correlation functions revealed a robust correlation (∼0.75) between the UV and X-ray light curves. The variations in the X-ray band are found to lead those in the FUV and NUV bands by ∼7.4 ks and ∼24.2 ks, respectively. The UV lags favour the thermal disc reprocessing model. The FUV and NUV bands are strongly correlated (∼0.9) and the variations in the FUV band lead those in the NUV band by ∼13 ks. Comparison of the UV lags found using the AstroSat observations with those reported earlier and the theoretical model for thermal reverberation timelag suggests a possible change in either the geometry of the accretion disc/corona or the height of the corona. [ABSTRACT FROM AUTHOR]

The prototypical powerful FR II radio galaxy Cygnus A fits extremely well into the quasar/radio galaxy unified model: high polarization with an angle almost perpendicular to the radio jet and polarized flux showing broad permitted lines. It has been claimed that ionized gas in the torus reveals a very clear torus shape via Bremmstrahlung emission. We rule out the later with an energetic argument, and we constrain the molecular and atomic gas properties with existing observations. The atomic absorption against the core has been shown to match the X-ray column only if the spin temperature is an implausible T s = 1 × 106 K. This points to a molecular medium for the X-ray column |$\log (N_{\rm H} ~[\rm {cm^{-2}}]) \sim 23.5$|⁠. Yet not low-J CO absorption is detected to sensitive limits. The non-detection is surprising given that this powerful radio galaxy hosts a luminous, dust-obscured active nucleus and copious warm molecular hydrogen. These conditions suggest a detectable level of emission. Furthermore, the torus X-ray column density suggests detectable absorption. We explore various possibilities to explain the lack of a signature from warm CO (200–250 K). Specifically, that the radiative excitation by the radio core renders low-J CO absorption below current sensitivities, and that high-J levels are well populated and conducive to producing absorption. We test this hypothesis using archival Hershel /SPIRE FTS observations of Cygnus A of high-J CO lines (14 ≥ J ≥ 4 transitions). Still high-J CO lines are not detected. We suggest that ALMA observations near its high frequency limit can be critical to obtain the signature of molecular line of the torus of Cygnus A. [ABSTRACT FROM AUTHOR]

We present an archival Atacama Large Millimeter/submillimeter Array (ALMA) study of the cyanide radical (CN) N  = 1 − 0/carbon monoxide (CO) J  = 1 − 0 intensity ratio in nearby (z < 0.05) ultra-luminous and luminous infrared galaxies (U/LIRGs). We identify 16 U/LIRGs that have been observed in both CN and CO lines at ∼500 pc resolution based on 16 different ALMA projects. We measure the (CN bright)/CO and (CN bright)/(CN faint) intensity ratios at an ensemble of molecular clouds scales (CN bright = CN N  = 1 − 0, J  = 3/2 − 1/2; CN faint = CN N  = 1 − 0, J  = 1/2 − 1/2 hyperfine groupings). Our global measured (CN bright)/CO ratios range 0.02–0.15 in LIRGs and 0.08–0.17 in ULIRGs. We attribute the larger spread in LIRGs to the variety of galaxy environments included in our sample. Overall, we find that the (CN bright)/CO ratio is higher in nuclear regions, where the physical and excitation conditions favour increased CN emission relative to the disc regions. 10 out of 11 galaxies which contain well-documented active galactic nuclei show higher ratios in the nucleus compared with the disc. Finally, we measure the median resolved (CN bright)/(CN faint) ratio and use it to estimate the total integrated CN line optical depth in ULIRGs (τ ∼ 0.96) and LIRGs (τ ∼ 0.23). The optical depth difference is likely due to the higher molecular gas surface densities found in the more compact ULIRG systems. [ABSTRACT FROM AUTHOR]

In this work, we analyse three average-luminosity hard X-ray selected AGN: ESO 506-G27, IGR J19039+3344, and NGC 7465. They have simultaneous Swift /XRT and NuSTAR data never published before and have been poorly studied at X-ray energies. These sources make for interesting targets both from a methodological and scientific point of view. Scientifically, they are of interest since they are possibly heavily absorbed objects, belong to a peculiar class and are variable both in flux and in spectral shape. Methodologically, because it is an interesting exercise to understand how existing spectral models can be applied to faint sources and how the use of NuSTAR data alone and then simultaneous and/or average data impacts on the spectral parameters determination. In this work, we demonstrate that simultaneous data are not sufficient if their statistical quality is poor. Moreover, we show that also the use of time-averaged data when dealing with faint AGN does not always provide confident results as for brighter AGN. Regardless of the poor data quality employed in our analysis, we are able to provide insights into the spectral characteristics of each source. We analyse in detail for the first time the iron line complex of ESO 506-G27, finding not only the presence of the iron K α and K β lines, but also of the iron K edge around 7 keV in the NuSTAR data. We also highlight changes in the absorption properties of IGR J19039+3344 and confirm NGC 7465 to be an unabsorbed type 1 LINER. [ABSTRACT FROM AUTHOR]

We present a 3D radiative transfer model for the spectral energy distribution (SED) of NGC 1365, which is a 'changing look' Seyfert 1.8 type active galactic nucleus (AGN). The SED from the ultraviolet (UV) to the infrared (IR) is constructed using archival data from the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat , along with IR data from the literature. The skirt radiative transfer code is used to model the SED and derive the geometry and composition of dust in this AGN. Similar to our earlier SED model of NGC 4151, the nuclear region of NGC 1365 is assumed to contain a ring or disc-like structure concentric to the accretion disc, composed of large (0.1–1  |$\mu$| m) graphite grains in addition to the two-phase dusty torus made up of interstellar-medium-type grains (Ring And Torus or RAT model). We also include, for the first time, an additional component of dusty wind in the form of a bipolar cone. We carry out a detailed analysis and derive the best-fitting parameters from a χ2 test to be R in, r = 0.03 pc, σ = 26°, and τtotal = 20 for the assumed ring–torus–polar wind geometry. Our results suggest the presence of hot dust at a temperature T ∼ 1216 K at the location of the ring that absorbs and scatters the incident UV radiation and emits in the near-IR. In the mid-IR, the major contributors are the polar cone and warm dust with T ∼ 914 K at R in, t = 0.1 pc. Not only are our model radii in agreement with IR interferometric observations, but also our study reiterates the role of high-resolution UV observations in constraining the dust grain size distribution in the nuclear regions of AGN. [ABSTRACT FROM AUTHOR]

Studies of spatial distribution, kinematics, and physical structure of dense molecular gas in the centres of galaxies is crucial in understanding the nature of physical processes, especially those related to active galactic nuclei (AGNs) and starbursts, in the vicinity of central massive black holes. However, our current understanding of dense gas in the circumnuclear discs (CND) remains limited, particularly those around AGNs. Here-, we report high-resolution deep observations of the CS (3−2), HC3N (15−14), H2CO (2−1), CH3CCN (8−7), CO (1−0), and (3−2) lines, toward the central region (R  ∼ 0.4 kpc) of the nearest Seyfert-2 galaxy, the Circinus galaxy, using the Atacama Large Millimeter/submillimeter Array. The dense molecular gas traced by CS (3−2) and HC3N (15−14) exhibit an asymmetric and cloud structure, which is in sharp contrast against the symmetric low-density structure traced by CO (1−0). Four molecular cloud structures surrounding the AGN, which have a typical size of ∼ 20 pc, are detected with the optically thin HC3N (15−14) line. HC3N (15−14)/CO (1−0) line ratio in the CND is found to be higher than that in the nuclear region, indicating that the bulk of dense gas accumulates in the CND, instead of the nucleus. HC3N (15−14) line and optically thick tracers in four molecular clouds, provide a good comparison between density layers and show evidence for a density stratification of the CND. [ABSTRACT FROM AUTHOR]

We present the results from an analysis of deep Herschel far-infrared (far-IR) observations of the edge-on disc galaxy NGC 3079. The point spread function-cleaned Photodetector Array Camera and Spectrometer (PACS) images at 100 and 160 μm display a 25 × 25 kpc2 X-shape structure centred on the nucleus that is similar in extent and orientation to that seen in H α, X-rays, and the far-ultraviolet. One of the dusty filaments making up this structure is detected in the Spectral and Photometric Imaging Receiver 250 μm map out to ∼25 kpc from the nucleus. The match between the far-IR filaments and those detected at other wavelengths suggests that the dusty material has been lifted out of the disc by the same large-scale galactic wind that has produced the other structures in this object. A closer look at the central 10 × 10 kpc2 region provides additional support for this scenario. The dust temperatures traced by the 100-160 μm flux ratios in this region are enhanced within a biconical region centred on the active galactic nucleus, aligned along the minor axis of the galaxy, and coincident with the well-known double-lobed cm-wave radio structure and H α-X-ray nuclear superbubbles. PACS imaging spectroscopy of the inner 6 kpc region reveals broad [C ii] 158 μm emission line profiles and OH 79 μm absorption features along the minor axis of the galaxy with widths well in excess of those expected from beam smearing of the disc rotational motion. This provides compelling evidence that the cool material traced by the [C ii] and OH features directly interacts with the nuclear ionized and relativistic outflows traced by the H α, X-ray, and radio emission.

Quasars emission is highly variable, and this variability gives us clues to understand the accretion process onto supermassive black holes. We can expect variability properties to correlate with the main physical properties of the accreting black hole, i.e. its mass and accretion rate. It has been established that the relative amplitude of variability anticorrelates with the accretion rate. The dependence of the variance on black hole mass has remained elusive, and contradicting results, including positive, negative, or no correlation, have been reported. In this work, we show that the key to these contradictions lies in the times-cales of variability studied (e.g. the length of the light curves available). By isolating the variance on different time-scales in well-defined mass and accretion rate bins we show that there is indeed a negative correlation between black hole mass and variance and that this anticorrelation is stronger for shorter time-scale fluctuations. The behaviour can be explained in terms of a universal variability power spectrum for all quasars, resembling a broken power law where the variance is constant at low temporal frequencies and then drops continuously for frequencies higher than a characteristic (break) frequency f b, where f b correlates with the black hole mass. Furthermore, to explain all the variance results presented here, not only the normalization of this power spectrum must anticorrelate with the accretion rate, but also the shape of the power spectra at short time-scales must depend on this parameter as well. [ABSTRACT FROM AUTHOR]

Most active galactic nuclei (AGNs) in the local Universe are obscured. In these obscured AGNs, an excess is usually observed in the soft X-rays below ∼2 keV above the absorbed X-ray continuum. This spectral component is associated with the scattering of X-ray photons off free electrons in the narrow-line region (NLR), and/or to photoionized lines. Recent studies have found that in highly obscured AGNs this component has lower flux relative to the primary X-ray continuum than in less obscured AGNs. This is measured by the scattering fraction, or f scatt, which is the ratio of the scattered flux to the continuum. Here, we use the ray-tracing platform reflex to perform simulations of scattered X-ray radiation to test two possible explanations for this phenomenon: (1) sources with lower f scatt are viewed at higher inclinations or (2) low f scatt sources are characterized by larger covering factors. We consider a conical NLR of free electrons, while allowing the column density and opening angle (and hence covering factor) to vary. We also consider electron densities inferred from observations, and from simulations carried out with the spectral synthesis code cloudy. Our simulations show f scatt is expected to be related to both the inclination angle and covering factor of the torus; however, the observed negative correlation between f scatt and N H can only be explained by a positive relation between the column density and the covering factor of the obscuring material. Additional contributions to f scatt can come from unresolved photoionized lines and ionized outflowing gas. [ABSTRACT FROM AUTHOR]

Mrk 783 is a narrow-line Seyfert 1 galaxy that possesses a relatively large two-sided radio emission extending up to 14 kpc from the active nucleus possibly connected with a large-scale ionized gas emission. We obtained a deep [O iii] image that revealed an extended system of emission knots and diffuse ionized gas surrounding the main galaxy. The highly-excited gas is related not only to the radio structure, but also to tidal features illuminated by the active nucleus radiation up to the projected distance of 41 kpc as it follows from the emission lines' intensities and kinematics derived from the long-slit spectroscopic data. Moreover, the part of the disk of the companion galaxy SDSS J130257.20+162537.1, located at ∼99 kpc projected distances to the north of Mrk 783, also falls in the AGN ionizing cone. It is possiblethat Mrk 783 can be considered as 'Hanny's Voorwerp precursor', i.e., a galaxy that demonstrates signs of sequential switching from radio-loud to radio-quiet nuclear activity, in the moment before its ionization luminosity falls. [ABSTRACT FROM AUTHOR]

Multiwavelength observations of active galactic nuclei (AGNs) often reveal various time-scales of variability. Among these phenomena, 'changing-look AGNs' are extreme cases where broad emission lines become faint/bright or even disappear/emerge between multi-epoch observations, providing crucial information about AGN internal structures. We here focus on 'changing-state' AGNs, specifically investigating the transition of optical spectra over years to tens of years. Based on the axisymmetric radiation-hydrodynamic simulations (Paper I) for the gas dynamics within the dust sublimation radius, we investigate the spectral properties of ionized gas exposed to the radiation from an AGN with a 107 M⊙ supermassive black hole. We find significant time-dependent variations in the Balmer emission lines by utilizing post-process pseudo-three-dimensional calculations and the spectral synthesis code cloudy. The equivalent width of H α and H β changes by a factor of 3, or the emission lines even disappear during 30 yr for the same viewing angle. The time-dependent behaviour arises primarily from gas dynamics, particularly the formation of non-steady, radiation-driven outflows within the innermost region of the disc (r ≲ 10−3 pc). The intricate interplay between non-spherical radiation sources at the core of AGNs and the dynamic behaviour of gas within the dust sublimation radius gives rise to radiation-driven outflows. This non-steady outflow potentially contributes to the observed variability in Balmer line emissions over multiyear time-scales in certain AGNs. [ABSTRACT FROM AUTHOR]

The Seyfert 2 galaxy NGC 2273 is a prime target to explore how active nuclei can be fed. It has a star‐forming innermost nuclear ring with a radius of 0.33kpc from where material may be funneled to the supermassive black hole in its center. In this article, we discuss high‐resolution adaptive optics aided JHKs images of NGC 2273 taken with the Large Binocular Telescope. Using Galfit we decomposed the innermost part of NGC 2273 into a core, a disk, and a ring using 58 parameters, 44 of them were used to describe the ring. The stellar mass of the ring was found to be 12 ×108M⊙$$ \times 1{0}^8{\mathrm{M}}_{\odot } $$, a factor of 10 higher than its molecular gas mass. A continuous gas flow via the main stellar bar of NGC 2273 during the lifetime of the bar of up to 10 M⊙yr−1$$ {\mathrm{M}}_{\odot }{\mathrm{yr}}^{-1} $$ is required to provide the fuel for the formation of the stars unless the star formation efficiency is on the order of 10%. This does not affect the fueling of the nuclear source as the amount of molecular gas required for this low‐luminosity active galaxy to achieve this is on the order of 104M⊙$$ 1{0}^4{\mathrm{M}}_{\odot } $$ only. [ABSTRACT FROM AUTHOR]

Ionization cones and relativistic jets give us one of the most large-scale example of active galactic nuclei (AGN) influence on the surrounding gas environment in galaxies and beyond. The study of ionization cones makes it possible not only to test the predictions of the unified model of galactic activity, but also to probe galaxy gas environment and trace how the luminosity of the nucleus changes over time (a light echo). In the external galactic or even extragalactic gas ionization cones create Extended Emission-Line Regions (EELRs) which can span distances from several to hundreds kpc away a host galaxy. We review the recent results of studying the gas kinematics and its ionization properties in EELRs with a special attention to search of fading AGN radiation on the time scale few × (10 4 − 10 5) years.The role of modern narrow-band and integral-field surveys in these researches is also considered. [ABSTRACT FROM AUTHOR]

In this paper, we present an updated version of our model (KYNXiltr) which considers thermal reverberation of a standard Novikov–Thorne accretion disc illuminated by an X-ray point-like source. Previously, the model considered only two cases of black hole spins, and assumed a colour correction factor f col = 2.4. Now, we extend the model to any spin value and f col. In addition, we consider two scenarios of powering the X-ray corona, either via accretion, or external to the accretion disc. We use KYNXiltr to fit the observed time lags obtained from intense monitoring of four local Seyfert galaxies (NGC 5548, NGC 4593, Mrk 817, and Fairall 9). We consider various combinations of black hole spin, colour correction, corona height, and fraction of accretion power transferred to the corona. The model fits well the overall time-lag spectrum in these sources (for a large parameter space). For NGC 4593 only, we detect a significant excess of delays in the U band. The contribution of the diffuse BLR emission in the time-lag spectrum of this source is significant. It is possible to reduce the large best-fitting parameter space by combining the results with additional information, such as the observed Eddington ratio and average X-ray luminosity. We also provide an update to the analytic expression provided by Kammoun et al. for an X-ray source that is not powered by the accretion process, which can be used for any value of f col, and for two values of the black hole spin (0 and 0.998). [ABSTRACT FROM AUTHOR]

We separately assess elemental abundances in active galactic nuclei's (AGNs) broad and narrow emission line regions (BLR and NLR), based on a critical assessment of published results together with new photoionization models. We find (1) He/H enhancements in some AGN, exceeding what can be explained by normal chemical evolution and confirm, (2) super-solar α abundance, though to a lesser degree than previously reported. We also reaffirm, (3) an N/O ratio consistent with secondary production, (4) solar or slightly sub-solar Fe abundance, and (5) red-shift independent metallicity, in contrast with galactic chemical evolution. We interpret (6) the larger metallicity in the BLR than NRL in terms of an in situ stellar evolution and pollution in AGN discs (SEPAD) model. We attribute (a) the redshift independence to the heavy element pollutants being disposed into the disc and accreted onto the central supermassive black hole (SMBH), (b) the limited He excess to the accretion–wind metabolism of a top-heavy population of evolving massive main sequence stars, (c) the super-solar CNO enrichment to the nuclear synthesis during their post-main-sequence evolution, (d) the large N/O to the byproduct of multiple stellar generations, and (e) the Mg, Si, and Fe to the ejecta of type II supernovae in the disc. These results provide supporting evidence for (f) ongoing self-regulated star formation, (g) adequate stellar luminosity to maintain marginal gravitational stability, (h) prolific production of seeds, and (i) dense coexistence of subsequently grown residual black hole populations in AGN discs. [ABSTRACT FROM AUTHOR]

We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging X-ray Polarimetry Explorer (IXPE) observed the source for ∼500 ks, supported by XMM–Newton (∼60 ks) and NuSTAR (∼80 ks) exposures. We detect polarization in the 2–8 keV band with 2.97σ confidence. We report a polarization degree of 3.3 ± 1.1 per cent and a polarization angle of 78° ± 10° (errors are 1σ confidence). The X-ray polarization is consistent with being aligned with the radio jet, albeit partially due to large uncertainties on the radio position angle. We jointly fit the spectra from the three observatories to constrain the presence of a relativistic reflection component. From this, we obtain constraints on the inclination angle to the inner disc (<39° at 99 per cent confidence) and the disc inner radius (<11 gravitational radii at 99 per cent confidence), although we note that modelling systematics in practice add to the quoted statistical error. Our spectropolarimetric modelling indicates that the 2–8 keV polarization is consistent with being dominated by emission directly observed from the X-ray corona, but the polarization of the reflection component is completely unconstrained. Our constraints on viewer inclination and polarization degree tentatively favour more asymmetric, possibly out-flowing, coronal geometries that produce more highly polarized emission, but the coronal geometry is unconstrained at the 3σ level. [ABSTRACT FROM AUTHOR]

We present a selection technique to detect Compton-thick (CT) active galactic nuclei (AGNs) in the 3XMM/SDSS-DR7 cross-correlation. A subsample of 3481 X-ray sources that are detected in the hard band (2–8 keV) and have photometric redshifts constitute our parent sample. We first applied an automated spectral-fitting procedure to select highly absorbed sources (N H > 1023 cm−2). We found 184 highly absorbed candidates. Then, we performed the Bayesian Monte Carlo Markov chains (MCMCs) selection technique to find CT AGNs. We also tested the MCMC selection technique by applying Monte Carlo simulations. We found that the method is accurate at 90 per cent independently of the nature of the underlying source. Our sample contains 52 bona fide CT AGNs. The CT AGNs were selected to have a range >0.75 of probability of being CT when either fitting with the two models Torus and MYTorus. About 75 per cent of CT AGNs in our sample had probabilities >90 per cent. From the spectral analysis, we significantly found an anticorrelation between the equivalent width of the neutral Fe K α line and the X-ray luminosity at 2–10 keV, the so-called X-ray Baldwin effect. [ABSTRACT FROM AUTHOR]

We report on the second observation of the radio-quiet active galactic nucleus MCG-05-23-16 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation started on 2022 November 6 for a net observing time of 640 ks, and was partly simultaneous with NuSTAR (86 ks). After combining these data with those obtained in the first IXPE pointing on 2022 May (simultaneous with XMM–Newton and NuSTAR) we find a 2–8 keV polarization degree Π = 1.6 ± 0.7 (at 68 per cent confidence level), which corresponds to an upper limit Π = 3.2 per cent (at 99 per cent confidence level). We then compare the polarization results with Monte Carlo simulations obtained with the monk code, with which different coronal geometries have been explored (spherical lamppost, conical, slab, and wedge). Furthermore, the allowed range of inclination angles is found for each geometry. If the best-fitting inclination value from a spectroscopic analysis is considered, a cone-shaped corona along the disc axis is disfavoured. [ABSTRACT FROM AUTHOR]

We present the results of a continuum reverberation mapping study of the radio-quiet type 1 Seyfert galaxy IRAS 09149−6206. The analysis was performed using X-ray, ultraviolet (UV), and optical observations made with the Swift telescope between 2017 January and December. The time delays between different light curves were measured using three different algorithms: PyI2CCF, PyROA, and JAVELIN. Our results show that the time delays increase with wavelength after τ ∝ λ4/3, as predicted for a geometrically thin and optically thick accretion disc, but only after accounting for significant diffuse continuum emission from the broad-line region. However, the measured size of the accretion disc can be up to five times larger than that predicted by standard theory. To our surprise, the strong increase in soft X-ray fluxes is delayed by about 15 d compared to the optical UV fluctuations, which challenges the prediction of the lamp-post model. Our analysis of the X-ray variability reveals the presence of a non-variable spectral component at 0.3–6.0 keV along with variable excess emission at 2.0–3.0 keV, which could be partly related to relativistic reflection in the inner region of the accretion disc. IRAS 09149−6206 joins the list of objects for which the traditional lamp-post model cannot explain the observed time delays. A scenario that incorporates other geometric considerations into the lamp-post model, e.g. an extended corona along a scattering source, might be better suited to explain the observed long time delays. [ABSTRACT FROM AUTHOR]

Complex Fe-K emission/absorption line features are commonly observed in the 6–11 keV band from Active Galactic Nuclei (AGN). These features are formed in various physical components surrounding the black holes. The Narrow-Line Seyfert 1 (NLS1) galaxy Mrk 766, in particular, exhibits characteristic blue-shifted Fe-K absorption lines caused by the ultrafast outflow (UFO), and a broad Fe-K emission line, as well as variable absorbers partially covering the X-ray emitting region. We re-analyse the Mrk 766 archival data of XMM-Newton, NuSTAR , and Swift to investigate the origin of the Fe-K line feature and the 0.3–79 keV energy spectral variation. We have found that the spectral variation in ≲10 keV is primarily explained by the variable partial covering of the central X-ray source by multilayer absorbing clouds. The Fe-K line feature consists of the blue-shifted absorption lines due to the UFO, a narrow emission line from the distant material, a broad emission line from the inner-disc reflection, and a slightly broadened weak emission line at around 6.4–6.7 keV whose equivalent width is ∼0.05 keV. The last one is presumably due to the resonance scattering in the UFO out of the line-of-sight, as predicted by a Monte Carlo simulation based on the hydrodynamical UFO modelling. We suggest that the seemingly complex Fe-K line features and the X-ray energy spectra of Mrk 766 are explained by a moderately extended central X-ray source around a Schwarzschild black hole, an optically thick accretion disc with a truncated inner-radius, the UFO, multilayer partial covering clouds, and a torus. [ABSTRACT FROM AUTHOR]