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Recent studies on dwarf galaxies reveal that some of them harbour a massive black hole (BH), which is believed to have a similar mass of the supermassive BH 'seeds' at early times. The origin and growth of the primitive BHs are still open questions, since these BH seeds are hardly observed at high redshifts. Therefore, MBH of dwarf galaxies can be the perfect candidates to untangle BH 'seeds' properties and their influence on their host galaxy evolution, since MBH may preserve their initial conditions due to its quiet merger and accretion histories. We use optical integral field unit observations, obtained with the Gemini GMOS-IFU, to study the gas emission and kinematics in four dwarf galaxies, candidates to host MBH, based on the analysis of their [Fe  x ] luminosities measured from SDSS spectra. The [Fe  x ] emission line is not detected in our GMOS in any of the galaxies, prompting speculation that its absence in our recent data may stem from a past tidal disruption event coinciding with the observation period of the SDSS data. All galaxies exhibit extended gas emissions, and the spatially resolved emission-line ratio diagnostic diagrams present values that suggest active galactic nuclei (AGN) photoionization from the [S  ii ]–BPT diagram. The gas velocity fields of all galaxies are indicative of disturbed rotation patterns, with no detection of gas outflows in any of the sources. Although the [S  ii ]–BPT diagrams indicate AGN photoionization, further confirmation through multiwavelength observations is required to validate this scenario. [ABSTRACT FROM AUTHOR]

Observations of high-redshift quasars frequently promote suggestions of large black hole masses, whose presence so early in cosmic time is not easily explicable. I consider the parallel with ultraluminous X-ray sources (ULXs) – now known to be stellar-mass black hole (and neutron star) binaries apparently radiating far above their Eddington luminosities L Edd. The true luminosity in ULXs is actually only of order L Edd, for stellar-mass accretors, but has a very anisotropic ('beamed') component, plus a near-isotropic component of similar luminosity but much lower specific intensity. Observers viewing ULXs from within the beam but assuming spherical symmetry deduce a luminosity ≫ L Edd. These features appear because the accretors are fed mass at highly super-Eddington rates, most of it expelled in high-speed (v > 0.2 c) outflows from the accretion disc. I show that in similarly beamed AGN, emission-line properties would be essentially the same as in unbeamed sources, but standard virial mass indicators unusable because velocity widths are dominated by the outflows, not bound motions about the black holes. In an ensemble of this kind the apparently most luminous systems are always the most distant, but have the lowest black hole masses. Interpreting observations of this ensemble without knowing that they are beamed leads instead to very high black hole mass estimates. The analogy with ULXs therefore suggests that high-redshift quasars might actually have central black hole masses which could have grown from stellar values within the lookback time. I consider how one might test these ideas observationally. [ABSTRACT FROM AUTHOR]

Reverberation mapping is the leading technique used to measure direct black hole masses outside of the local Universe. Additionally, reverberation measurements calibrate secondary mass-scaling relations used to estimate single-epoch virial black hole masses. The Australian Dark Energy Survey (OzDES) conducted one of the first multi-object reverberation mapping surveys, monitoring 735 AGN up to z ∼ 4, over 6 years. The limited temporal coverage of the OzDES data has hindered recovery of individual measurements for some classes of sources, particularly those with shorter reverberation lags or lags that fall within campaign season gaps. To alleviate this limitation, we perform a stacking analysis of the cross-correlation functions of sources with similar intrinsic properties to recover average composite reverberation lags. This analysis leads to the recovery of average lags in each redshift-luminosity bin across our sample. We present the average lags recovered for the Hβ, Mg  ii , and C  iv samples, as well as multiline measurements for redshift bins where two lines are accessible. The stacking analysis is consistent with the Radius–Luminosity relations for each line. Our results for the Hβ sample demonstrate that stacking has the potential to improve upon constraints on the R – L relation, which have been derived only from individual source measurements until now. [ABSTRACT FROM AUTHOR]

Identifying methods to discover dual active galactic nucleus (AGN) has proven to be challenging. Several indirect tracers have been explored in the literature, including X/S-shaped radio morphologies and double-peaked (DP) emission lines in the optical spectra. However, the detection rates of confirmed dual AGN candidates from the individual methods remain extremely small. We search for binary black holes (BBH) in a sample of six sources that exhibit both X-shaped radio morphology and DP emission lines using the Very Long Baseline Array (VLBA). Three out of the six sources show dual VLBA compact components, making them strong candidates for BBH sources. In addition, we present deep uGMRT images revealing the exquisite details of the X-shaped wings in three sources. We present a detailed precession modeling analysis of these sources. The black hole separations estimated from the simplistic geodetic precession model are incompatible with those estimated from emission line offsets and the VLBA separations. However, precession induced by a non-coplanar secondary black hole is a feasible mechanism for explaining the observed X-shaped radio morphologies and the black hole separations estimated from other methods. The black hole separations estimated from the double-peaked emission lines agree well with the VLBA compact component separations. Future multifrequency VLBA observations will be critical in ruling out or confirming the BBH scenario in the three galaxies with dual component detections. [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]

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]

We identify a fading AGN SDSS J220141.64+115124.3 from the internal Product Launch-11 (MPL-11) in Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The central region with a projected radius of |$\sim$| 2.4 kpc is characterized as LINER-like line ratios while the outskirts extended to |$\sim$| 15 kpc show Seyfert-like line ratios. The |${\rm{[O {\small III}]}}$| |$\lambda$| 5007 luminosity of the Seyfert regions is a factor of 37 (2) higher than the LINER regions without (with) dust attenuation correction, suggesting that the AGN activity decreases at least |$\sim$| 8 |$\times$| 10 |$^3$| yr (⁠|$\sim$| 2.4 kpc/light-speed) ago. We model the emission line spectra in the central region with double Gaussian components (a narrow core and a broad wing) and analyse the properties of each component. The narrow core component mostly co-rotates with the stellar disc, whereas the broad wing component with a median of the velocity dispersion |$\sim$| 300 km s |$^{-1}$| is related to a wind outflow. The kinematic position angle (PA) of the ionized gas shows an |$\sim 20^{\circ }$| twist from the galaxy centre to 1.5 effective radius. The median of the PA difference between the gas and stellar components is as large as |$\sim 50^{\circ }$| within 0.4 effective radius. The tidal feature in DESI image and star–gas misalignment suggest this galaxy is a merger remnant. Combining all these observational results as well as public available X-ray and MIR luminosities, we confirm this is a fading AGN, the merger process kick-started the central engine to quasar phase which ionized gas composed of tidal debris, and now the activity of the central black hole decreases. The discontinuity in |${\rm{[O {\small III}]}}$| |$\lambda$| 5007 flux and EQW maps is due to multiple AGN outbursts triggered by merger remnant gas inflows. [ABSTRACT FROM AUTHOR]

We selected sources with a steep soft-X-ray-band spectrum with a photon index of Γ > 2.5 – measured by eROSITA on board the Spectrum-Röntgen-Gamma (SRG) – from the eFEDS AGN catalogue as candidates of highly accreting supermassive black holes, and investigated their multi-wavelength properties. Among 601 bright AGN with 0.2−5 keV counts of greater than 100, 83 sources (≈14%) are classified as steep-spectrum sources. These sources have typical 0.5−2 keV luminosities of LSX ≈ 1044 erg s−1 and the majority of them are found at redshifts below z = 1. In comparison with sources with flatter spectra, these sources have, on average, a UV (or optical) to 2 keV luminosity ratio that is larger by ∼0.3 dex and bluer optical-to-UV continuum emission. They also appear to be radio quiet based on the detection rate in the FIRST and VLASS surveys. Their host galaxies – at least in the redshift range of z = 0.2 − 0.8, where the AGN–galaxy decomposition results from the Subaru Hyper Suprime-Cam imaging are available – tend to be late-type and have smaller stellar masses (M⋆ ∼ 1010.5 M⊙) than those of sources with flatter spectra. These properties are similar to those found in nearby narrow-line Seyfert 1 galaxies, in agreement with the picture that they are AGN with elevated accretion rates and are in the early growth phase of black hole and galaxy co-evolution. However, the steep-spectrum sources are not exclusively narrow-line Seyfert 1 galaxies; indeed many are broad-line Seyfert 1 galaxies, as found by a catalogue search. This suggests that these steep-spectrum sources may be black holes generally with high accretion rates but of a wide mass range, including a few objects emitting at LSX ≥ 1045 erg s−1, of which black hole masses can be close to 109 M⊙. [ABSTRACT FROM AUTHOR]

With an X-ray stacking analysis of |$\simeq 12\, 000$| Lyman-break galaxies (LBGs) using the Chandra Legacy Survey image, we investigate average supermassive black hole (SMBH) accretion properties of star-forming galaxies (SFGs) at 4 ≲ z ≲ 7. Although no X-ray signal is detected in any stacked image, we obtain strong 3σ upper limits for the average black hole accretion rate (BHAR) as a function of star formation rate (SFR). At z ∼ 4 (5) where the stacked image is deeper, the 3σ BHAR upper limits per SFR are ∼1.5 (1.0) dex lower than the local black hole-to-stellar mass ratio, indicating that the SMBHs of SFGs in the inactive (BHAR |$\lesssim 1 \, \mathrm{M}_\odot$| yr−1) phase are growing much more slowly than expected from simultaneous evolution. We obtain a similar result for BHAR per dark halo accretion rate. QSOs from the literature are found to have ∼1 dex higher SFRs and ≳ 2 dex higher BHARs than LBGs with the same dark halo mass. We also make a similar comparison for dusty starburst galaxies and quiescent galaxies from the literature. A duty-cycle corrected analysis shows that for a given dark halo, the SMBH mass increase in the QSO phase dominates over that in the much longer inactive phase. Finally, a comparison with the TNG300, TNG100, SIMBA100, and EAGLE100 simulations finds that they overshoot our BHAR upper limits by ≲ 1.5 dex, possibly implying that simulated SMBHs are too massive. [ABSTRACT FROM AUTHOR]

In this paper, very blue-shifted broad Hα with a shifted velocity of ∼2200 km s–1 is reported in the low-redshift type-1.9 active galactic nucleus (AGN) SDSS J1052+1036. Blue-shifted broad emission lines may arise owing to the presence of a rotating gas disc around a central black hole (BH), but may also be a signature of rare phenomena such as the gravitational wave recoil of a supermassive BH (rSMBH) or the presence of a binary BH (BBH) system. Here, owing to the higher shifted velocity of the stronger and wider blue-shifted broad Hα, the BBH system is disfavoured. Meanwhile, if this object contains a rSMBH, intrinsic obscuration with E (B – V) ≤ 0.6 should lead to a detectable broad Hβ, indicating that the rSMBH scenario is not preferred. We find that the blue-shifted broad Hα can be well explained by emission from an AGN disc, indicating that SDSS J1052+1036 is likely a disc-emitting AGN. In order to determine which scenario, a rSMBH or a disc-emitter, is preferred, a re-observed spectrum in 2025 could provide robust clues, with a disc-emitter probably leading to clear variations of peak positions, peak separations, and/or peak intensity ratios in broad Hα, but with a rSMBH scenario probably leading to no variations of peak separations in broad Hα. [ABSTRACT FROM AUTHOR]

We observed the blazar 2200 + 420 in the I, R, and V bands using the 1.0 m telescope at Weihai Observatory of Shandong University on eight nights in October 2022 and obtained over 3800 data points. Using the F-test and ANOVA test, we analysed the light curves and found intra-day (IDV) variability every night. We found that all variability amplitudes (Amp) are over 10 per cent, except for 2022 October 22, with four nights having amplitudes above 20 per cent and the maximum amplitude reaching over 42 per cent. Additionally, we discovered a minimal variability time-scale of 24.6 min and a bluer-when-brighter (BWB) trend on intra-day for this object. No significant time lag between different bands was detected during the eight nights of observation. Based on the shortest variability time-scale and a model assuming the variations arise close to the central black hole that are adverted into the jet, we estimated the upper limits of the black hole mass to be MBH  = 8.6 × 107 M⊙. The BWB trend on intra-day supports the shock-in-jet model, which can also explain the IDV of blazars. [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]

The black hole mass M BH is crucial in constraining the growth of supermassive black holes within their host galaxies. Since direct measurements of M BH with dynamical methods are restricted to a limited number of nearly quiescent nearby galaxies and a small minority of active galactic nuclei (AGN), we must rely on indirect methods. In this work, we utilize an unbiased, volume-limited, hard X-ray selected sample of AGN to compare the reliability of some commonly used indirect methods, emphasizing those that can be applied to obscured AGN. Based on a subsample of AGN with M BH determined via dynamical methods, our study suggests that X-ray-based techniques, such as the scaling method and the one based on the variability measured through the excess variance, are in good agreement with the dynamical methods. On the other hand, the M –σ⋆ correlation based on inactive galaxies tends to systematically overestimate M BH, regardless of the level of obscuration. We provide a correcting factor that produces an acceptable agreement with dynamical values and can be used to quickly correct the M BH computed with this method. We also derive an alternative M –σ⋆ correlation based on this unbiased sample of AGN with a slope considerably shallower than the ones obtained using inactive galaxies, suggesting that the latter may not be appropriate to compute the M BH in AGN. Finally, we find that no quick fix can be applied to correct the M BH obtained from the fundamental plane of black hole activity, casting doubts on the reliability of this method. [ABSTRACT FROM AUTHOR]

We study in detail the inner ∼600 pc of the Seyfert 2 galaxy ESO 138-G001 by means of the Soar Integral Field Spectrograph attached to the SOAR telescope. This source is known for displaying a very rich coronal line spectrum and a blob of high-excitation emission ∼3 arcsec south-east (SE) of the active galactic nucleus (AGN). The nature of this emission has not been fully understood yet. The excellent spatial and spectral resolution of SIFS allows us to confirm that the bulk of the coronal line forest emission region is very compact, of ∼0.8 arcsec in diameter, centred on the AGN and most likely powered by radiation from the AGN. In addition, evidence of a nuclear outflow, restricted to the inner 1 arcsec centred at the nucleus is found based on the detection of broad components in the most important emission lines. The gas in the inner few tens of parsecs filters out the AGN continuum so that the NLR is basically illuminated by a modified SED. This scenario is confirmed by means of photoionization models that reproduce the most important lines detected in the SIFS field of view. From the modelling, we also found that the black hole mass M BH of the AGN is about 105.50 M⊙, in agreement with previous X-ray observations. The spectrum of the SE blob is dominated by emission lines of low- to mid-ionization, with no hints of coronal lines. Our results show that it represents gas in the ionization cone that is photoionized by the filtered central AGN continuum. [ABSTRACT FROM AUTHOR]

We investigate the physical properties, such as star-forming activity, disc versus bulge nature, galaxy size, and obscuration of 3811 SRG/ eROSITA -detected AGNs at 0.2 < z < 0.8 in the eFEDS field. Using Subaru Hyper Suprime-Cam imaging data in the grizy bands, we measure the structural and stellar properties for their host galaxies by performing a 2D AGN-host image decomposition. We find that (1) AGNs can contribute significantly to the total optical light down to |${\rm log}\, L_{\rm X}\sim 42.5\ \rm erg\ s^{-1}$|⁠ , thus ignoring the AGN component can significantly bias the structural measurements; (2) AGN hosts are predominately star-forming galaxies at |${\rm log}\, \mathcal {M}_\star \lesssim 11.3\, \mathrm{M}_\odot$|⁠ ; (3) the bulk of AGNs (64 per cent) reside in galaxies with significant stellar discs (⁠|$\rm S\acute{e}rsic$|  index n < 2), while their host galaxies become increasingly bulge dominated (n ∼ 4) and quiescent at |${\rm log}\, \mathcal {M}_\star \gtrsim 11.0\, \mathrm{M}_\odot$|⁠ ; (4) the size–stellar mass relation of AGN hosts tends to lie between that of inactive (i.e. non-AGN) star-forming, and quiescent galaxies, suggesting that the physical mechanism responsible for building the central stellar density also efficiently fuel the black hole growth; (5) the hosts of X-ray unobscured AGNs are biased towards face-on systems, suggesting that some of the obscuration of the nuclei could come from galaxy-scale gas and dust. This will bias against the detection of unobscured AGNs in gas-rich star-forming galaxies, which may partly account for the deficiency of star-forming discs as host galaxies for the most massive AGNs (missing star-forming fraction up to |$\sim 40{{\ \rm per\ cent}}$|⁠). Our results are consistent with a scenario in which the black hole and galaxy transform in structure and star-forming activity while grow in mass, as desired to establish the local |$\mathcal {M}_{\rm BH}-\mathcal {M}_{\rm bulge}$| relation. [ABSTRACT FROM AUTHOR]

Quenching of star formation in the central galaxies of cosmological halos is thought to result from energy released as gas accretes onto a supermassive black hole. The same energy source also appears to lower the central density and raise the cooling time of baryonic atmospheres in massive halos, thereby limiting both star formation and black hole growth, by lifting the baryons in those halos to greater altitudes. One predicted signature of that feedback mechanism is a nearly linear relationship between the central black hole's mass (M BH) and the original binding energy of the halo's baryons. We present the increasingly strong observational evidence supporting a such a relationship, showing that it extends up to halos of mass M halo ∼ 1014 M ⊙. We then compare current observational constraints on the M BH– M halo relation with numerical simulations, finding that black hole masses in IllustrisTNG appear to exceed those constraints at M halo < 1013 M ⊙ and that black hole masses in EAGLE fall short of observations at M halo ∼ 1014 M ⊙. A closer look at IllustrisTNG shows that quenching of star formation and suppression of black hole growth do indeed coincide with black hole energy input that lifts the halo's baryons. However, IllustrisTNG does not reproduce the observed M BH– M halo relation because its black holes gain mass primarily through accretion that does not contribute to baryon lifting. We suggest adjustments to some of the parameters in the IllustrisTNG feedback algorithm that may allow the resulting black hole masses to reflect the inherent links between black hole growth, baryon lifting, and star formation among the massive galaxies in those simulations. [ABSTRACT FROM AUTHOR]

In a previous work, we have identified the spin of the dominant black hole of a binary from its jet properties. Analysing Very Long Baseline Array (VLBA) observations of the quasar S5 1928+738, taken at 15-GHz during 43 epochs between 1995.96 and 2013.06, we showed that the inclination angle variation of the inner (<2 mas) jet symmetry axis naturally decomposes into a periodic and a monotonic contribution. The former emerges due to the Keplerian orbital evolution, while the latter is interpreted as the signature of the spin-orbit precession of the jet emitting black hole. In this paper, we revisit the analysis of the quasar S5 1928+738 by including new 15-GHz VLBA observations extending over 29 additional epochs, between 2013.34 and 2020.89. The extended data set confirms our previous findings which are further supported by the flux density variation of the jet. By applying an enhanced jet precession model that can handle arbitrary spin orientations κ with respect to the orbital angular momentum of a binary supermassive black hole system, we estimate the binary mass ratio as ν = 0.21 ± 0.04 for κ = 0 (i.e. when the spin direction is perpendicular to the orbital plane) and as ν  = 0.32 ± 0.07 for κ = π/2 (i.e. when the spin lies in the orbital plane). We estimate more precisely the spin precession velocity, halving its uncertainty from |$(-0.05\pm 0.02)$| to |$(-0.04\pm 0.01)^{\circ }\, \mathrm{yr}^{-1}$|⁠. [ABSTRACT FROM AUTHOR]

The black hole (BH) mass and luminosity are key factors in determining how a quasar interacts with its environment. In this study, we utilize data from the European Southern Observatory Large Programme XQ-100, a high-quality sample of 100 X-shooter spectra of the most luminous quasars in the redshift range 3.5 < z < 4.5, and measure the properties of three prominent optical and ultraviolet broad emission lines present in the wide wavelength coverage of X-shooter: C  iv , Mg  ii , and H β. The line properties of all three broad lines are used for virial estimates of the BH mass and their resulting mass estimates for this sample are tightly correlated. The BH mass range is |$\log {(\rm {\mathit{ M}_{BH}}/\rm {M_\odot })} = 8.6{\!-\!}10.3$| with bolometric luminosities estimated from the 3000 Å continuum in the range |$\log {(\rm {\mathit{ L}_{bol}}/\rm {erg\, s^{-1}})} = 46.7{\!-\!}48.0$|⁠. Robustly determined properties of these quasars enable a variety of follow-up research in quasar astrophysics, from chemical abundance and evolution in the broad-line region to radiatively driven quasar outflows. [ABSTRACT FROM AUTHOR]

We compute synthetic, rest-frame optical and ultraviolet (UV) emission-line properties of galaxy populations at redshifts from z  ≈ 0 to  = 8 in a full cosmological framework. We achieve this by coupling, in post-processing, the cosmological IllustrisTNG simulations with new-generation nebular-emission models, accounting for line emission from young stars, post-asymptotic giant branch (PAGB) stars, accreting black holes (BHs) and, for the first time, fast radiative shocks. The optical emission-line properties of simulated galaxies dominated by different ionizing sources in our models are largely consistent with those expected from classical diagnostic diagrams and reflect the observed increase in [O  iii ]/Hβ at fixed [N  ii ]/Hα and the evolution of the Hα, [O  iii ]λ5007, and [O  ii ] λ3727 luminosity functions from z  ≈ 0 to ∼ 2. At higher redshift, we find that the emission-line galaxy population is dominated by star-forming and active galaxies, with negligible fractions of shock- and PAGB-dominated galaxies. We highlight 10 UV-diagnostic diagrams able to robustly identify the dominant ionizing sources in high-redshift galaxies. We also compute the evolution of several optical- and UV-line-luminosity functions from z  = 4 to 7, and the number of galaxies expected to be detectable per field of view in deep, medium-resolution spectroscopic observations with the NIRSpec instrument on board the JWST. We find that 2-h-long exposures are sufficient to achieve unbiased censuses of Hα and [O  iii ]λ5007 emitters, while at least 5 h are required for Hβ, and even 10 h will detect only progressively smaller fractions of [O  ii ] λ3727, O  iii ] λ1663, C  iii ] λ1908, C  iv  λ1550, [N  ii ]λ6584, Si  iii ] λ1888, and He  ii  λ1640 emitters, especially in the presence of dust. [ABSTRACT FROM AUTHOR]

Dual active galaxy nuclei (dAGNs) trace the population of post-merger galaxies and are the precursors to massive black hole (MBH) mergers, an important source of gravitational waves that may be observed by the Laser Interferometer Space Antenna (LISA). In Paper I of this series, we used the population of ≈2000 galaxy mergers predicted by the TNG50-3 simulation to seed semi-analytic models of the orbital evolution and coalescence of MBH pairs with initial separations of ≈1 kpc. Here, we calculate the dAGN luminosities and separations of these pairs as they evolve in post-merger galaxies, and show how the coalescence fraction of dAGNs changes with redshift. We find that because of the several gigayear-long dynamical friction timescale for orbital evolution, the fraction of dAGNs that eventually end in an MBH merger grows with redshift and exceeds 50% beyond z dAGN ≈ 1. Dual AGNs in galaxies with bulge masses ≲1010 M ⊙, or consisting of near-equal-mass MBHs, evolve more quickly and have higher than average coalescence fractions. At any redshift, dAGNs observed with small separations (≲0.7 kpc) have a higher probability of merging before z = 0 than more widely separated systems. Radiation feedback effects can significantly reduce the number of MBH mergers, and this could be manifested as a larger than expected number of widely separated dAGNs. We present a method to estimate the MBH coalescence rate as well as the potential LISA detection rate given a survey of dAGNs. Comparing these rates to the eventual LISA measurements will help determine the efficiency of dynamical friction in post-merger galaxies. [ABSTRACT FROM AUTHOR]

Dynamical perturbations from supermassive black hole (SMBH) binaries can increase the rates of tidal disruption events (TDEs). However, most previous work focuses on TDEs from the heavier black hole in the SMBH binary (SMBHB) system. In this work, we focus on the lighter black holes in SMBHB systems and show that they can experience a similarly dramatic increase in their TDE rate due to perturbations from a more massive companion. While the increase in TDEs around the more massive black hole is mostly due to chaotic orbital perturbations, we find that, around the smaller black hole, the eccentric Kozai–Lidov mechanism is dominant and capable of producing a comparably large number of TDEs. In this scenario, the mass derived from the light curve and spectra of TDEs caused by the lighter SMBH companion is expected to be significantly smaller than the SMBH mass estimated from galaxy scaling relations, which are dominated by the more massive companion. This apparent inconsistency can help find SMBHB candidates that are not currently accreting as active galactic nuclei and that are at separations too small for them to be resolved as two distinct sources. In the most extreme cases, these TDEs provide us with the exciting opportunity to study SMBHBs in galaxies where the primary SMBH is too massive to disrupt Sun-like stars. [ABSTRACT FROM AUTHOR]

The activity of central supermassive black holes might affect the alignment of galaxy spin axes with respect to the closest cosmic filaments. We exploit the Sydney–AAO Multi-object Integral-field Galaxy Survey to study possible relations between black hole activity and the spin–filament alignments of stars and ionized gas separately. To explore the impact of instantaneous black hole activity, active galaxies are selected according to emission-line diagnostics. Central stellar velocity dispersion (σc) is used as a proxy for black hole mass and its integrated activity. We find evidence for the gas spin–filament alignments to be influenced by AGN, with Seyfert galaxies showing a stronger perpendicular alignment at fixed bulge mass with respect to galaxies, where ionization is consequence of low-ionization nuclear emission-line regions (LINERs) or old stellar populations (retired galaxies). On the other hand, the greater perpendicular tendency for the stellar spin–filament alignments of high-bulge mass galaxies is dominated by retired galaxies. Stellar alignments show a stronger correlation with σc compared to the gas alignments. We confirm that bulge mass (M bulge) is the primary parameter of correlation for both stellar and gas spin–filament alignments (with no residual dependency left for σc), while σc is the most important property for secular star formation quenching (with no residual dependency left for M bulge). These findings indicate that M bulge and σc are the most predictive parameters of two different galaxy evolution processes, suggesting mergers trigger spin–filament alignment flips and integrated black hole activity drives star formation quenching. [ABSTRACT FROM AUTHOR]

We study the morphologies and structures of 57 dwarf galaxies that are representative of the general population of dwarf galaxies and compare their demographics to a sample of dwarf galaxies hosting optically selected active galactic nuclei (AGNs). The two samples span the same galaxy stellar mass (109 ≲ M ⋆/ M ⊙ ≲ 109.5) and color range, and the observations are well-matched in physical resolution. The fractions of irregular galaxies (14%) and early types/ellipticals (∼18%) are nearly identical among the two samples. However, among galaxies with disks (the majority of each sample), the AGN hosts almost always have a detectable (pseudo)bulge, while a large fraction of the non-AGN hosts are pure disk galaxies with no detectable (pseudo)bulge. Central point sources of light consistent with nuclear star clusters are detected in many of the non-AGN hosts. In contrast, central point sources detected in the AGN hosts are, on average, more than 2 orders of magnitude more luminous, suggesting the point sources in these objects are dominated by AGN light. The preference for (pseudo)bulges in dwarf AGN hosts may inform searches for massive black holes in dwarf galaxies and attempts to constrain the black hole occupation fraction, which, in turn, has implications for our understanding of black hole seeding mechanisms. [ABSTRACT FROM AUTHOR]

A Spectroscopic study has been focused in this article to study one of the main types of active galaxies which are quasars, and to be more precise this research focuses on studying the correlation between the main engine of Quasi-Stellar Objects (QSO), the central black hole mass (SMBH) and other physical properties (e.g. the star formation rate (SFR)). Twelve objects have been randomly selected for “The Half Million Quasars (HMQ) Catalogue” published in 2015 and the data collected from Salon Digital Sky survey (SDSS) Dr. 16. The redshift range of these galaxies were between (0.05 – 0.17). The results show a clear linear proportionality between the SMBH and the SFR, as well as direct proportional between the luminosity at V-band and the central black hole masses of the QSO. Furthermore, the calculation exhibits the ration between the SMBH and it hosts bulge approximately equal to 10-3 . [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 used Transiting Exoplanet Survey Satellite (TESS) data to identify 29 candidate active galactic nuclei (AGNs) through their optical variability. The high-cadence, high-precision TESS light curves present an opportunity for the identification of AGNs, including those not selected through other methods. Of the candidates, we found that 18 have either previously been identified as AGNs in the literature or could have been selected based on emission-line diagnostics, mid-IR colours, or X-ray luminosity. AGNs in low-mass galaxies offer a unique window into supermassive black hole and galaxy co-evolution and 8 of the 29 candidates have estimated black hole masses ≲ 106 M⊙. The low-mass galaxies NGC 4395 and NGC 4449 are two of our five 'high-confidence' candidates. Since our initial sample largely draws from just nine TESS sectors, we expect to identify at least ∼45 more candidates in the TESS primary and extended mission data sets, of which ∼60 per cent will be new AGNs and ∼20 per cent will be in low-mass galaxies. [ABSTRACT FROM AUTHOR]

Active galaxies contain a supermassive black hole at their center that grows by accreting matter from the surrounding galaxy. The accretion process in about the central 10 parsecs has not been directly resolved in previous observations because of the small apparent angular sizes involved. We observed the active nucleus of the Circinus galaxy using submillimeter interferometry. A dense inflow of molecular gas was evident on subparsec scales. We calculated that less than 3% of this inflow is accreted by the black hole, with the rest being ejected by multiphase outflows, providing feedback to the host galaxy. Our observations also reveal a dense gas disk surrounding the inflow that is gravitationally unstable, which drives the accretion into about the central 1 parsec. [ABSTRACT FROM AUTHOR]

Eclipsing of the X-ray emitting region in active galactic nuclei (AGN) is a potentially powerful probe to examine the AGN environment and absorber properties. Here, we study the eclipse data from the 2016 XMM–Newton observation of NGC 6814 using a colour–colour analysis. Colours (i.e. hardness ratios) can provide the advantage of better time resolution over spectral analysis alone. Colour–colour grids are constructed to examine the effects of different parameters on the observed spectral variability during the eclipse. Consistent with previous spectral analysis, the variations are dominated by changes in the column density and covering fraction of the absorber. However, during maximum eclipse the behaviour of the absorber changes. Just after ingress, the eclipse is described by changes in column density and covering fraction, but prior to egress, the variations are dominated by changes in column density alone. Simulations are carried out to consider possible absorber geometries that might produce this behaviour. The behaviour is inconsistent with a single homogeneous cloud, but simulations suggest that multiple clouds, perhaps embedded in a highly ionized halo, could reproduce the results. In addition, we determine the orbital covering factor (fraction of orbital path-length) based on evidence of several eclipses in the 2016; 64-d Swift light curve. We estimate that ∼2–4 per cent of the orbit is covered by obscuring clouds and that the distribution of clouds is not isotropic. [ABSTRACT FROM AUTHOR]

We examine the quenching characteristics of 328 isolated dwarf galaxies 10 8 < M star / M ⊙ < 10 10 within the Romulus25 cosmological hydrodynamic simulation. Using mock-observation methods, we identify isolated dwarf galaxies with quenched star formation and make direct comparisons to the quenched fraction in the NASA Sloan Atlas (NSA). Similar to other cosmological simulations, we find a population of quenched, isolated dwarf galaxies below M star < 109 M ⊙ not detected within the NSA. We find that the presence of massive black holes (MBHs) in Romulus25 is largely responsible for the quenched, isolated dwarfs, while isolated dwarfs without an MBH are consistent with quiescent fractions observed in the field. Quenching occurs between z = 0.5–1, during which the available supply of star-forming gas is heated or evacuated by MBH feedback. Mergers or interactions seem to play little to no role in triggering the MBH feedback. At low stellar masses, M star ≲ 109.3 M ⊙, quenching proceeds across several Gyr as the MBH slowly heats up gas in the central regions. At higher stellar masses, M star ≳ 109.3 M ⊙, quenching occurs rapidly within 1 Gyr, with the MBH evacuating gas from the central few kpc of the galaxy and driving it to the outskirts of the halo. Our results indicate the possibility of substantial star formation suppression via MBH feedback within dwarf galaxies in the field. On the other hand, the apparent overquenching of dwarf galaxies due to MBH suggests that higher-resolution and/or better modeling is required for MBHs in dwarfs, and quenched fractions offer the opportunity to constrain current models. [ABSTRACT FROM AUTHOR]

Even when the direct view towards the active nucleus is obscured, nuclear emission propagating along other directions can scatter off surrounding material, become polarized and reach the observer. Spectropolarimetry can thus be an important tool in investigating the circumnuclear geometry and kinematics of quasars on scales that cannot yet be probed via direct observations. Here, we discuss an intriguing class of quasars where the polarization position angle swings by large amounts (⁠|$\sim 90\deg$|⁠) within an emission line. We investigate a kinematic model in which the scattering dust or electrons are in an axisymmetric outflow. We propagate Stokes parameters in a variety of geometries of emitter, scatterer, and observer. We use these models to predict polarization fraction, line profiles, and polarization position angles and compare them to observations. We demonstrate that the swinging polarization angle can be a result of the geometry of the outflow and the orientation of the observer. Polarization properties of a near-Eddington extremely red quasar SDSS J1652 can be successfully explained by a model in which the quasar is surrounded by a geometrically thick disc, whose 'skin' is outflowing at ∼1000 km s−1 and acts as the scatterer on scales of a few tens of pc. The line of sight to the observer in this source is within or close to the skin of the torus, in agreement with multiwavelength data. Spectropolarimetric data and models presented here strongly support the thick-disc geometry of circumnuclear material suggested by recent numerical simulations of high-rate accretion flows on to black holes. [ABSTRACT FROM AUTHOR]

Given the anisotropic emission from quasar accretion discs, their viewing angle affects estimates of the quasar luminosity, black hole mass, and Eddington ratio. Discs appear overluminous when viewed pole-on and underluminous when viewed at high inclination. In radio-quiet quasars, the viewing angle is usually unknown, although spectroscopic indicators have been proposed. Here, we use a recently discovered universality in the variability structure function (SF) of quasar light curves (LCs), where all quasars show the same SF when clocks run in units of orbital time-scale. As an offset from the mean relation can be caused by incorrect orbital time-scales and thus incorrect luminosities, we correlate these offsets with suggested inclination indicators. We derive SFs from NASA/Asteroid Terrestrial-impact Last Alert System (ATLAS) LCs spanning ∼6 yr of observation, using a sample of 183 luminous quasars with measured H β lines as well as 753 quasars with C  iv and Mg  ii lines. Starting from the proposed orientation indicators, we expect quasars with narrower H β lines and with more blueshifted C  iv lines to be viewed more pole-on and thus appear overluminous. In contrast, our SF analysis finds that presumed pole-on discs appear underluminous, consistently for both line indicators. We discuss possible explanations for the behaviour of quasars with highly blueshifted C  iv lines irrespective of inclination angle, including dusty outflows that might render the accretion disc underluminous and flatter disc temperature profiles with longer orbital time-scales than in thin-disc models but reach no satisfying conclusion. [ABSTRACT FROM AUTHOR]

While in massive galaxies active galactic nucleus (AGN) feedback plays an important role, the role of AGN feedback is still under debate in dwarf galaxies. With well spatially resolved data obtained from the Multi-Unit Spectroscopic Explorer, we identify a spatially extended (⁠|$\rm \sim 3\,\, kpc$|⁠) and fast (⁠|$V_{80} \sim 471\,\, \rm km\,\,s^{-1}$|⁠) AGN-driven outflow in a dwarf galaxy: Sloan Digital Sky Survey J022849.51-090153.8 with |$M_{*} \sim 10^{9.6}\,\,{\rm {\rm M}_{\odot }}$| that host an intermediate-mass black hole of |$M_{\rm BH} \sim 10^5\,\,{\rm {\rm M}_{\odot }}$| and L AGN/ L Edd ∼ 0.15. Through the measurement of the rotation curve, we estimate the escape velocity of the halo and the ratio of the outflow velocity to the halo escape velocity to be 1.09 ± 0.04, indicating that the outflow is capable of escaping not only the galaxy disc but the halo. The outflow size of our AGN is found to be larger than AGN in massive galaxies at the given AGN [O  iii ] luminosity, while the size of the photoionized narrow-line region is comparable. These results suggest the important role of AGN feedback through outflows in dwarf galaxies when their central intermediate-mass black holes accrete at high-Eddington ratios. [ABSTRACT FROM AUTHOR]

Spectroscopic studies of extreme-ionization galaxies (EIGs) are critical to our understanding of exotic systems throughout cosmic time. These EIGs exhibit spectral features requiring >54.42 eV photons: the energy needed to ionize helium into He2+ fully and emit He ii recombination lines. Spectroscopic studies of EIGs can probe exotic stellar populations or accretion onto intermediate-mass black holes (∼102–105 M ⊙), which are the possibly key contributors to the reionization of the Universe. To facilitate the use of EIGs as probes of high-ionization systems, we focus on ratios constructed from several rest-frame UV/optical emission lines: [O iii ] λ 5008, H β, [Ne iii ] λ 3870, [O ii ] λ λ 3727, 3729, and [Ne v ] λ 3427. These lines probe the relative intensity at energies of 35.12, 13.62, 40.96, 13.62, and 97.12 eV, respectively, covering a wider range of ionization than traced by other common rest-frame UV/optical techniques. We use the ratios of these lines ([Ne v ]/[Ne iii ] ≡ Ne53, [O iii ]/H β, and [Ne iii ]/[O ii ]), which are nearby in wavelength, mitigating the effects of dust attenuation and uncertainties in flux calibration. We make predictions from photoionization models constructed from Cloudy that use a broad range of stellar populations and black hole accretion models to explore the sensitivity of these line ratios to changes in the ionizing spectrum. We compare our models to observations from the Hubble Space Telescope and JWST of galaxies with strong high-ionization emission lines at z ∼ 0, z ∼ 2, and 5 < z < 8.5. We show that the Ne53 ratio can separate galaxies with ionization from "normal" stellar populations from those with active galactic nuclei and even "exotic" Population III models. We introduce new selection methods to identify galaxies with photoionization driven by Population III stars or intermediate-mass black hole accretion disks that could be identified in upcoming high-redshift spectroscopic surveys. [ABSTRACT FROM AUTHOR]

By means of the data sets of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), we investigate the relationship between the variability amplitude and luminosity at 5100 Å, black hole mass, Eddington ratio, R Fe II (the ratio of the flux of Fe II line within 4435–4685 Å to the broad proportion of H β line) as well as R 5007 (the ratio of the flux [O III] line to the total H β line) of the broad line Seyfert 1 (BLS1) and narrow line Seyfert 1 (NLS1) galaxies sample in g, r, i, z and y bands, respectively. We also analyze the similarities and differences of the variability characteristics between the BLS1 galaxies and NLS1 galaxies. The results are listed as follows. (1). The cumulative probability distribution of the variability amplitude shows that NLS1 galaxies are lower than that in BLS1 galaxies. (2). We analyze the dependence of the variability amplitude with the luminosity at 5100 Å, black hole mass, Eddington ratio, R Fe II and R 5007 , respectively. We find significantly negative correlations between the variability amplitude and Eddington ratio, insignificant correlations with the luminosity at 5100 Å. The results also show significantly positive correlations with the black hole mass and R 5007 , significantly negative correlations with R Fe II which are consistent with (Rakshit and Stalin in Astrophys. J. 842: 96, 2017) in low redshift bins (z < 0.4) and (Ai et al. in Astrophys. J. Lett. 716:L31, 2010). (3). The relationship between the variability amplitude and the radio loudness is investigated for 155 BLS1 galaxies and 188 NLS1 galaxies. No significant correlations are found in our results. [ABSTRACT FROM AUTHOR]

We study the time variability (over ≤7.3 yr) of ultra fast outflows (UFOs) detected in a sample of 64 C iv broad absorption line (BAL) quasars (with 80 distinct BAL components) monitored using the Southern African Large Telescope. By comparing the properties of the quasar in our sample with those of a control sample of non-BAL quasars, we show that the distributions of black hole mass are different and the bolometric luminosities and optical photometric variations of UFO BAL quasars are slightly smaller compared to that of non-BAL quasars. The detection fraction of C  iv equivalent width (W) variability (∼95 per cent), the fractional variability amplitude |$\left(\frac{\Delta W}{W}\right)$| and the fraction of 'highly variable' BAL (i.e. |$\big|$| |$\frac{\Delta W}{W}$| |$\big|$| > 0.67) components (∼33 per cent) are higher in our sample compared to the general BAL population. The scatter in |$\frac{\Delta W}{W}$| and the fraction of 'highly variable' BALs increase with the time-scale probed. The |$\frac{\Delta W}{W}$| distribution is asymmetric at large time scales. We attribute this to the BAL strengthening time-scales being shorter than the weakening time-scales. The BAL variability amplitude correlates strongly with the BAL properties compared to the quasar properties. BALs with low W, high-velocity, shallow profiles, and low-velocity width tend to show more variability. When multiple BAL components are present, a correlated variability is seen between low- and high-velocity components with the latter showing a larger amplitude variations. We find an anticorrelation between the fractional variations in the continuum flux and W. While this suggests photoionization induced variability, the scatter in continuum flux is much smaller than that of W. [ABSTRACT FROM AUTHOR]

We examine the dual [both black hole (BH) active] and offset (one BH active and in distinct galaxies) active galactic nucleus (AGN) population (comprising ∼ 2000 pairs at |$0.5\, \text{kpc}\lesssim \Delta r\lt 30\, \text{kpc}$|⁠) at z  = 2 ∼ 3 in the ASTRID simulation covering (360 cMpc)3. The dual (offset) AGN make up 3.0(0.5) per cent of all AGN at z  = 2. The dual fraction is roughly constant while the offset fraction increases by a factor of 10 from z  = 4 ∼ 2. Compared with the full AGN population, duals are characterized by low M BH/ M * ratios, high specific star formation rates (sSFR) of |$\sim 1\, \text{Gyr}^{-1}$|⁠ , and high Eddington ratios (∼0.05, double that of single AGN). Dual AGNs are formed in major galaxy mergers (typically involving |$M_\text{halo}\lt 10^{13}\, M_\odot$|⁠), with simular-mass BHs. At small separations (when host galaxies are in the late phase of the merger), duals become 2 ∼ 8 times brighter (albeit more obscured) than at larger separations. 80  per cent of the bright, close duals would merge within |$\sim 500\, \text{Myr}$|⁠. Notably, the initially less-massive BHs in duals frequently become the brighter AGN during galaxy mergers. In offset AGN, the active BH is typically ≳ 10 times more massive than its non-active counterpart and than most BHs in duals. Offsets are predominantly formed in minor galaxy mergers with the active BH residing in the centre of massive haloes (⁠|$M_\text{ halo}\sim 10^{13-14}\, \mathrm{M}_\odot$|⁠). In these deep potentials, gas stripping is common and the secondary quickly deactivates. The stripping also leads to inefficient orbital decay amongst offsets, which stall at |$\Delta r\sim 5\, \text{kpc}$| for a few hundred Myrs. [ABSTRACT FROM AUTHOR]

We present a new constraint on the mass of the black hole in the active S0 galaxy NGC 5273. Due to the proximity of the galaxy at 16.6 ± 2.1 Mpc, we were able to resolve and extract the bulk motions of stars near the central black hole using adaptive-optics-assisted observations with the Gemini Near-infrared Integral Field Spectrograph, as well as constrain the large-scale kinematics using archival Spectroscopic Areal Unit for Research and Optical Nebulae spectroscopy. High-resolution Hubble Space Telescope imaging allowed us to generate a surface-brightness decomposition, determine approximate mass-to-light ratios for the bulge and disk, and obtain an estimate for the disk inclination. We constructed an extensive library of dynamical models using the Schwarzschild orbit-superposition code FORSTAND, exploring a range of disk and bulge shapes, halo masses, etc. We determined a black hole mass of M • = [0.5–2] × 107 M ⊙, where the low side of the range is in agreement with the reverberation mapping measurement of M • = [4.7 ± 1.6] × 106 M ⊙. NGC 5273 is one of the few nearby galaxies that hosts a broad-lined active galactic nucleus, allowing a crucial comparison of black hole masses derived from independent mass-measurement techniques. [ABSTRACT FROM AUTHOR]

Context. During the commissioning of the James Webb Space Telescope (JWST), the mid-infrared instrument (MIRI) observed NGC 6552 with the MIRI Imager and the Medium-Resolution Spectrograph (MRS). NGC 6552 is an active galactic nucleus (AGN) at a redshift of 0.0266 (DL = 120 Mpc) classified as a Seyfert 2 nucleus in the optical and Compton-thick AGN in the X-ray. Aims. This work exemplifies and demonstrates the MRS capabilities to study the mid-infrared (mid-IR) spectra and characterise the physical conditions and kinematics of the ionised and molecular gas in the nuclear regions of nearby galaxies. Methods. MIRI Imager observations covers the full NGC 6552 galaxy at 5.6 m. MRS observations covers its nuclear region (3.64.3 kpc at 17.7-27.9 m) in a wavelength range between 4.9 and 27.9 m. These observations were obtained with the aim to investigate the persistence of the MIRI detectors (residual signal left from previous bright source observations). However, NGC 6552 observations demonstrate the performance and power of the MIRI instrument even with a non-optimal observational strategy. Results. We obtained the nuclear, circumnuclear, and central mid-IR spectra of NGC 6552. They provide the first clear observational evidence for a nuclear outflow in NGC 6552. The outflow contributes to 67±7% of the total line flux independent of the ionisation potential (27-187 eV) and critical densities (104-4106 cm3), showing an average blue-shifted peak velocity of 127±45 km s1 and an outflow maximal velocity of 698±80 km s1. Since the mid-IR photons penetrate dusty regions as effciently as X-ray keV photons, we interpret these results as the evidence for a highly ionised, non-stratified, AGN-powered, and fast outflowing gas in a low density environment (few 103 cm3) located very close (<0.2 kpc) to the Compton-thick AGN. Nine pure rotational molecular Hydrogen lines are detected and spectrally resolved, and exhibit symmetric Gaussian profiles, consistent with the galactic rotation, and with no evidence of outflowing H2 material. We detect a warm H2 mass of 1:9 ± 1:1 107 M in the central region (1.8 kpc in diameter) of the galaxy, with almost 30% of that mass in the circumnuclear region. Line ratios confirm that NGC 6552 has a Seyfert nucleus with a black hole mass estimated in the range of 0.6-6 million solar masses. Conclusions. This work demonstrates the power of the newly commissioned MIRI Medium Resolution Spectrograph to reveal new insights in the kinematics and ionisation state of the interstellar medium around the dusty nuclear regions of nearby active galaxies. [ABSTRACT FROM AUTHOR]

The relation between the mass of the supermassive black hole (SMBH) in the center of galaxies and their bulge mass or central velocity dispersion is well known. This suggests a coevolution between the SMBHs and their galaxy hosts. Our aim is to study this relation, specifically, for radio loud galaxies, and as a function of redshift z. We selected a sample of 42 radio galaxies and active galactic nuclei (AGN) with broad emission lines and spectroscopic redshifts between z = 0:34 by cross-matching the low radio frequency sources from Very Large Array (VLA) FIRST with spectroscopically confirmed galaxies from wide-field surveys, including Sloan Digital Sky Survey (SDSS) DR14 ugriz and Dark Energy Survey (DES) DR2 grzY in the optical, Wield Infrared Survey Explorer (WISE), and the Galaxy And Mass Assembly (GAMA) spectroscopic survey. We characterized the stellar mass (M), star formation, and black hole properties (mass of the central SMBH, Eddington ratio, and jet power, Qjet). The relation between SMBH mass, M, and z is placed into context by comparing them with scaling relations (MBH-M, MBH=M-z, MBH-Qjet, and Qjet-) from the literature. On the basis of a multiwavelength spectral energy distribution modeling, our radio sources are broadly consistent with being on the star-forming main sequence. They have sub-Eddington accretion rates,' 1% on average, as typically found in type I AGN, while higher accretion rates favor more powerful jets to be launched by the central engine. We find overmassive SMBHs in (17±5)% of our radio sources, similarly to previous studies on nearby early-type galaxies. Altogether, an evolutionary scenario in which radio-mode AGN feedback regulates the accretion onto the SMBHs and the stellar mass assembly of the radio sources is discussed, which may explain the observed phenomenology. This pilot study represents a benchmark for future studies using wide-field surveys such as those with Euclid and the Vera Rubin Observatory. [ABSTRACT FROM AUTHOR]

Using blazar light curves from the optical All-Sky Automated Survey for Supernovae (ASAS-SN) and the γ-ray Fermi -LAT telescope, we performed the most extensive statistical correlation study between both bands, using a sample of 1180 blazars. This is almost an order of magnitude larger than other recent studies. Blazars represent more than 98 per cent of the AGNs detected by Fermi -LAT and are the brightest γ-ray sources in the extragalactic sky. They are essential for studying the physical properties of astrophysical jets from central black holes. However, their γ-ray flare mechanism is not fully understood. Multiwavelength correlations help constrain the dominant mechanisms of blazar variability. We search for temporal relationships between optical and γ-ray bands. Using a Bayesian Block Decomposition, we detect 1414 optical and 510 γ-ray flares, we find a strong correlation between both bands. Among all the flares, we find 321 correlated flares from 133 blazars, and derive an average rest-frame time delay of only 1.1 |$_{-8.5}^{+7.1}$| d, with no difference between the flat-spectrum radio quasars, BL Lacertae-like objects or low, intermediate, and high-synchrotron peaked blazar classes. Our time-delay limit rules out the hadronic proton-synchrotron model as the driver for non-orphan flares and suggests a leptonic single-zone model. Limiting our search to well-defined light curves and removing 976 potential but unclear 'orphan' flares, we find 191 (13 per cent) and 115 (22 per cent) clear 'orphan' optical and γ-ray flares. The presence of 'orphan' flares in both bands challenges the standard one-zone blazar flare leptonic model and suggests multizone synchrotron sites or a hadronic model for some blazars. [ABSTRACT FROM AUTHOR]

We study the Fourier time lags due to the Comptonization of disc-emitted photons in a spherical, uniform, and stationary X-ray corona, which located on the rotational axis of the black hole. We use monk , a general relativistic Monte Carlo radiative transfer code, to calculate Compton scattering of photons emitted by a thin disc with a Novikov–Thorne temperature profile. We find that the model time lags due to Comptonization remain constant up to a characteristic frequency and then rapidly decrease to zero at higher frequencies. We provide equations that can be used to determine the time lags and cross-spectra for a wide range of values for the corona radius, temperature, optical depth, height, and for various accretion rates and black hole masses. We also provide an equation for the X-ray luminosity of a single corona, as a function of its characteristics and location above the disc. Remarkably, the observed X-ray time lags of nearby, bright active galaxies can be successfully reproduced by inverse Comptonization process of multiple dynamic coronae. [ABSTRACT FROM AUTHOR]

RX J0134.2-4258 is one of the most super-Eddington narrow-line Seyfert 1 (NLS1) galaxies, on which we conducted a monitoring campaign from radio to X-rays. In this paper, we present a detailed analysis of its optical/UV spectra and broad-band spectral energy distribution. Our study shows that the preferred black hole mass of RX J0134.2-4258 is M BH ∼ 2 × 107 M⊙, giving a mass accretion rate through the outer disc of |$\dot{m}_{\rm out} \sim 20$| (assuming zero spin), compared to the observed luminosity ratio L bol/ L Edd ∼ 6. This reduction in radiative efficiency is expected for super-Eddington flows, as power can be lost via advection and/or disc winds. We find that the optical/UV lines of RX J0134.2-4258 resemble those from weak-like quasars (WLQs), as it has notably weak C iv and N v emission lines. It also has drastic X-ray variability, again similar to that recently observed in some other WLQs. However, WLQs have systematically higher masses (≳108 M⊙), and lower Eddington ratios (⁠|$\dot{m}_{\rm out} \sim 1$|⁠) than RX J0134.2-4258. We compare instead to the most extreme NLS1s, with similarly large |$\dot{m}_{\rm out}$| but smaller masses. These show similarly large reductions in radiative efficiency but their UV lines are not similarly wind dominated. We suggest a new category of weak-line Seyfert galaxies to describe sources like RX J0134.2-4258, and interpret its (so far unique) properties in a model, where the lower disc temperature in the higher mass black holes leads to the UV-line-driving mechanism, which enhances the super-Eddington radiation-pressure-driven wind. [ABSTRACT FROM AUTHOR]

This study aims to characterize, for the first time, intranight optical variability (INOV) of low-mass active galactic nuclei (LMAGNs) which host a black hole (BH) of mass MBH ∼ 106 M ⊙, i.e. even less massive than the Galactic centre BH Sgr A* and 2–3 orders of magnitude below the supermassive black holes (SMBHs, |$M_{BH}\, \sim \, 10^8 \rm{-} 10^9 M_{\odot }$|⁠), which are believed to power quasars. Thus, LMAGNs are a crucial subclass of AGNs filling the wide gap between SMBH and stellar-mass BHs of Galactic X-ray binaries. We have carried out a 36-session campaign of intranight optical monitoring of a well-defined, representative sample of 12 LMAGNs already detected in X-ray and radio bands. This set of LMAGNs is found to exhibit INOV at a level statistically comparable to that observed for blazars (MBH ≳ 108–9 M ⊙) and for the γ-ray-detected Narrow-line Seyfert1 galaxies (MBH ∼ 107 M ⊙) which, too, are believed to have relativistic jets. This indicates that the blazar-level activity can even be sustained by central engines with BHs near the upper limit for intermediate-mass BHs (⁠|$M_{BH}\, \sim \, 10^3 \rm{-}10^6 M_{\odot }$|⁠). [ABSTRACT FROM AUTHOR]

We conducted a Very Long Baseline Array (VLBA) observation of the low mass active galactic nucleus (AGN) in galaxy NGC 4293 (z  = 0.003). The object is associated with a low-ionization nuclear emission-line region (LINER). Its black hole mass is estimated as ∼105 or |${\sim}10^7 \, \mathrm{M}_\odot$|⁠. The VLBA 1.5 GHz image shows an inverse symmetric structure with two discrete radio blobs separated by an angular distance of ∼120 mas, corresponding to ∼7 parsec. Furthermore, its integrated radio spectrum has a turnover at the frequency of ∼0.44 GHz. Based on the compactness and spectrum, the nuclear radio source in NGC 4293 belongs to a sample of (megahertz) peaked spectrum (PS/MPS) radio sources with compact symmetric morphologies. NGC 4293 has 1.4 GHz radio power of only |${\sim}10^{20}\, \mathrm{W\, Hz^{-1}}$| with the VLBA observation, which is consistent with local AGNs but lower than the current PS samples. One of the two blobs has a steep radio spectrum α = −0.62 ± 0.08 (S ν ∝ ν+α), while the other one has an inverted spectrum α = 0.32 ± 0.10. The VLBA 1.5 GHz luminosity ratio of the two blobs is 3.23 and both blobs show lateral-flowing structures where the hotspots reside at the edge of each radio lobe. This can be explained as jet interactions with dense circumnuclear medium. We estimate the black hole mass of NGC 4293 through the Fundamental Plane of black hole activity, which constrains the black hole mass to be |${\lesssim}10^6\, \mathrm{M}_\odot$|⁠. It supports that the object is a low-mass AGN and a potential candidate for accreting and ejecting IMBHs. [ABSTRACT FROM AUTHOR]

We have studied the nuclear region of the previously detected dual AGN system in the galaxy pair IRAS 05589 + 2828 and 2MASX J06021107 + 2828382, through new optical spectroscopy observations, along with radio and X-ray archival data. Our multiwavelength data strongly suggest that the Sy1 IRAS 05589+2828  (z = 0.0330 ± 0.0002) conforms to a dual AGN system with the Sy2 2MASX J06021107 + 2828382  (z = 0.0334 ± 0.0001), with a projected separation obtained from the radio data of 20.08 arcsec  (∼13.3 kpc). Analysis of the optical spectra reveals a faint narrow extended emission from H α and [O iii ] amidst the two AGN, supporting evidence for an ongoing merger. IRAS 05589 + 2828  is a double component narrow emission-line AGN, with complex broad Balmer emission line profiles that clearly show a strong red-peaklet with a velocity shift of ∼3500  km s−1. The black hole mass estimates of IRAS  05589 + 2828  and 2MASX J06021107 + 2828382  are log M |$\rm _{BH}$|   =  8.59 ± 0.14 (M⊙) and log M |$\rm _{BH}$| = 8.21 ± 0.2 (M⊙), respectively. In the X-ray bands, IRAS 05589 + 2828  is compatible with a Type 1 object, showing both spectral and flux variability. Chandra   data of 2MASX J06021107 + 2828382 allowed us to measure a high hardness ratio in this source, providing evidence for a Type 2 AGN. The 22 GHz image obtained with the Karl G. Jansky Very Large Array has revealed that both AGN are compact radio objects with spectral indices −0.26 ± 0.03 and −0.70 ± 0.11, confirming for the first time its dual AGN nature in the radio bands. [ABSTRACT FROM AUTHOR]

It has been inferred from large unbiased samples that |$10$| – |$15{{\ \rm per\ cent}}$| of all quasars are radio-loud (RL). Using the quasar catalogue from the Sloan Digital Sky Survey, we show that the radio-loud fraction (RLF) for high broad line (HBL) quasars, containing H β full width at half-maximum greater than 15 000 km s−1, is |$\sim 57 {{\ \rm per\ cent}}$|⁠. While there is no significant difference between the RL and radio-quiet (RQ) populations in our sample in terms of their black hole mass, Eddington ratio, and covering fraction (CF), optical continuum luminosity of the RL quasars are higher. The similarity in the distribution of their CF indicates that our analysis is unbiased in terms of the viewing angle of the HBL RL and RQ quasars. Hence, we conclude that the accretion disc luminosity of the RL quasars in our HBL sample is higher, which indicates a connection between a brighter disc and a more prominent jet. By comparing them with the non-HBL H β broad emission line quasars, we find that the HBL sources have the lowest Eddington ratios in addition to having a very high RLF. That is consistent with the theories of jet formation, in which jets are launched from low Eddington ratio accreting systems. We find that the [O iii ] narrow emission line is stronger in the RL compared to RQ quasars in our HBL sample, which is consistent with previous findings in the literature, and may be caused by the interaction of the narrow line gas with the jet. [ABSTRACT FROM AUTHOR]

There is growing observational evidence for dwarf galaxies hosting active galactic nuclei (AGN), including hints of AGN-driven outflows in dwarfs. However, in the common theoretical model of galaxy formation, efficient supernova (SN) feedback is the tool of choice for regulating star formation in the low-mass regime. In this paper, we present a suite of high-resolution cosmological dwarf zoom-in simulations relaxing the assumption of strong SN feedback, with the goal to determine whether more moderate SN feedback in combination with an efficient AGN could be a suitable alternative. Importantly, we find that there are sufficient amounts of gas to power brief Eddington-limited accretion episodes in dwarfs. This leads to a variety of outcomes depending on the AGN accretion model: from no additional suppression to moderate regulation of star formation to catastrophic quenching. Efficient AGN can drive powerful outflows, depleting the gas reservoir of their hosts via ejective feedback and then maintaining a quiescent state through heating the circumgalactic medium. Moderate AGN outflows can be as efficient as the strong SN feedback commonly employed, leading to star formation regulation and H  i gas masses in agreement with observations of field dwarfs. All efficient AGN set-ups are associated with overmassive black holes (BHs) compared to the (heavily extrapolated) observed BH mass–stellar mass scaling relations, with future direct observational constraints in this mass regime being crucially needed. Efficient AGN activity is mostly restricted to high redshifts, with hot, accelerated outflows and high X-ray luminosities being the clearest tell-tale signs for future observational campaigns. [ABSTRACT FROM AUTHOR]

We study the nature of the faint radio source population detected in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Early Science data in the COSMOS field, focusing on the properties of the radio-loud active galactic nuclei (AGNs). Using the extensive multiwavelength data available in the field, we are able to classify 88 per cent of the 5223 radio sources in the field with host galaxy identifications as AGNs (35 per cent) or star-forming galaxies (54 per cent). We select a sample of radio-loud AGNs with redshifts out to z ∼ 6 and radio luminosities 1020 < L1.4 GHz/W Hz−1 < 1027 and classify them as high-excitation and low-excitation radio galaxies (HERGs and LERGs). The classification catalogue is released with this work. We find no significant difference in the host galaxy properties of the HERGs and LERGs in our sample. In contrast to previous work, we find that the HERGs and LERGs have very similar Eddington-scaled accretion rates; in particular we identify a population of very slowly accreting AGNs that are formally classified as HERGs at these low radio luminosities, where separating into HERGs and LERGs possibly becomes redundant. We investigate how black hole mass affects jet power, and find that a black hole mass ≳ 107.8 M⊙ is required to power a jet with mechanical power greater than the radiative luminosity of the AGN (L mech/ L bol > 1). We discuss that both a high black hole mass and black hole spin may be necessary to launch and sustain a dominant radio jet. [ABSTRACT FROM AUTHOR]

Studies of the rest-frame ultraviolet (UV) luminosity functions (LFs) typically treat star-forming galaxies and active galactic nuclei (AGNs) separately. However, modern ground-based surveys now probe volumes large enough to discover AGNs at depths sensitive enough for fainter galaxies, bridging these two populations. Using these observations as constraints, we present a methodology to empirically jointly model the evolution of the rest-UV LFs at z = 3â€"9. Our critical assumptions are that both populations have LFs well described by double power laws modified to allow for a flattening at the faint-end, and that all LF parameters evolve smoothly with redshift. This methodology provides a good fit to the observations and makes predictions to volume densities not yet observed, finding that the volume density of bright (M UV = âˆ'28) AGNs rises by ∼105 from z = 9 to z = 3, while bright (M UV = âˆ'21) star-forming galaxies rise by only ∼102 across the same epoch. The observed bright-end flattening of the z = 9 LF is unlikely to be due to AGN activity, and rather is due to a shallowing of the bright-end slope, implying a reduction of feedback in bright galaxies at early times. The intrinsic ionizing emissivity is dominated by star-forming galaxies at z > 3, even after applying a notional escape fraction. We find decent agreement between our AGN LFs and predictions based on different black hole seeding models, though all models underpredict the observed abundance of bright AGNs. We show that the wide-area surveys of the upcoming Euclid and Roman observatories should be capable of discovering AGNs to z ∼ 8. [ABSTRACT FROM AUTHOR]

We present an entirely new sample of 388 low-mass galaxies (M ⋆ ≤ 1010 M ⊙) that have spectroscopic signatures indicating the presence of massive black holes (BHs) in the form of active galactic nuclei (AGNs) or tidal disruption events. Of these, 70 have stellar masses in the dwarf galaxy regime with 108 ≲ M ⋆/ M ⊙ ≲ 109.5. We identify the active galaxies by analyzing optical spectra of a parent sample of ∼23,000 low-mass emission-line galaxies in the Galaxy and Mass Assembly (GAMA) Survey Data Release 4, and employing four different diagnostics based on narrow emission-line ratios and the detection of high-ionization coronal lines. We find that 47 of the 388 low-mass active galaxies exhibit broad H α in their spectra, corresponding to virial BH masses in the range M BH ∼ 105.0â€"7.7 M ⊙ with a median BH mass of 〈 M BH〉 ∼ 106.2 M ⊙. Our sample extends to higher redshifts (z ≤ 0.3; 〈 z 〉 = 0.13) than previous samples of AGNs in low-mass/dwarf galaxies based on Sloan Digital Sky Survey spectroscopy, which can be attributed to the spectroscopic limit of GAMA being ∼2 mag deeper. Moreover, our multi-diagnostic approach has revealed low-mass active galaxies spanning a wide range of properties, from blue star-forming dwarfs to luminous “miniquasars” powered by low-mass BHs. As such, this work has implications for BH seeding and AGN feedback at low masses. [ABSTRACT FROM AUTHOR]