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We present observations of mid- J (J = 4–3 or J = 5–4) carbon monoxide (CO) emission lines and continuum emission from a sample of ten of the most luminous (L bol |$\ge$| 10 |$^{14}$|  L |$\rm \odot$| ) Hot Dust-Obscured Galaxies (Hot DOGs) discovered by the Wide-field Infrared Survey Explorer (WISE) with redshifts up to 4.6. We uncover broad spectral lines (FWHM |$\ge$| 400 km s |$^{-1}$|⁠) in these objects, suggesting a turbulent molecular interstellar medium (ISM) may be ubiquitous in Hot DOGs. A halo of molecular gas, extending out to a radius of 5 kpc is observed in W2305–0039, likely supplied by 940 km s |$^{-1}$| molecular outflows. W0831+0140 is plausibly the host of a merger between at least two galaxies, consistent with observations made using ionized gas. These CO(4–3) observations contrast with previous CO(1–0) studies of the same sources: the CO(4–3) to CO(1–0) luminosity ratios exceed 300 in each source, suggesting that the lowest excited states of CO are underluminous. These findings show that the molecular gas in Hot DOGs is consistently turbulent, plausibly a consequence of AGN feedback, triggered by galactic mergers. [ABSTRACT FROM AUTHOR]

'Bare' active galactic nuclei (AGN) are a subclass of Type 1 AGN that show little or no intrinsic absorption. They offer an unobscured view of the central regions of the AGN and therefore serve as ideal targets to study the relativistic reflection features originating from the innermost regions of the accretion disc. We present a detailed broad-band spectral analysis (0.3–70 keV) of one of the most luminous bare AGN in the local Universe, RBS 1124 (⁠|$z= 0.208$|⁠) using a new, co-ordinated high signal-to-noise observation obtained by XMM – Newton and NuSTAR. The source exhibits a power-law continuum with |$\Gamma \sim$| 1.8 along with a soft excess below 2 keV, a weak neutral iron line and curvature at high energies (⁠|${\sim} 30$|  keV). The broad-band spectrum, including the soft excess and the high-energy continuum, is well fit by the relativistic reflection model when the accretion disc is allowed to have densities of log |$(n_{\rm e}$| /cm |$^{-3}$|⁠) |$\gtrsim 19.2$|⁠. Our analysis therefore suggests that when high-density effects are considered, relativistic reflection remains a viable explanation for the soft excess. [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]

The ability to accurately discern active massive black holes (BHs) in nearby dwarf galaxies is paramount to understanding the origins and processes of "seed" BHs in the early Universe. We present Chandra X-ray Observatory observations of a sample of three local dwarf galaxies (M * ≤ 3 × 109 M ⊙, z ≤ 0.15) previously identified as candidates for hosting active galactic nuclei (AGN). The galaxies were selected from the NASA-Sloan Atlas with spatially coincident X-ray detections in the eROSITA Final Equatorial Depth Survey. Our new Chandra data reveal three X-ray point sources in two of the target galaxies with luminosities between log(L 2−10 keV [erg s−1]) = 39.1 and 40.4. Our results support the presence of an AGN in these two galaxies and an ultraluminous X-ray source (ULX) in one of them. For the AGNs, we estimate BH masses of M BH ∼ 105−6 M ⊙ and Eddington ratios on the order of ∼10−3. [ABSTRACT FROM AUTHOR]

We present a focused X-ray and multiwavelength study of the ultraluminous weak-line quasar (WLQ) SDSS J1521+5202, one of the few X-ray weak WLQs that is amenable to basic X-ray spectral and variability investigations. J1521+5202 shows striking X-ray variability during 2006–2023, by up to a factor of ≈32 in 0.5–2 keV flux, and our new 2023 Chandra observation caught it in its brightest X-ray flux state to date. Concurrent infrared/optical observations show only mild variability. The 2023 Chandra spectrum can be acceptably described by a power law with intrinsic X-ray absorption, and it reveals a nominal intrinsic level of X-ray emission relative to its optical/ultraviolet emission. In contrast, an earlier Chandra spectrum from 2013 shows apparent spectral complexity that is not well fit by a variety of models, including ionized absorption or standard Compton-reflection models. Overall, the observations are consistent with the thick-disk plus outflow model previously advanced for WLQs, where a nominal level of underlying X-ray emission plus variable absorption leads to the remarkable observed X-ray variability. In the case of J1521+5202, it appears likely that the outflow, and not the thick disk itself, lies along our line of sight and causes the X-ray absorption. [ABSTRACT FROM AUTHOR]

Although supermassive black holes (SMBHs) reside in the heart of virtually every massive galaxy, it remains debated whether dwarf galaxies commonly host SMBHs. Because low-mass galaxies may retain memory of the assembly history of their black holes (BHs), probing the BH occupation fraction of local dwarf galaxies might offer insights into the growth and seeding mechanisms of the first BHs. In this work, we exploit the Western half of the eROSITA all-sky survey (covering 20,000 deg2) and compile a catalog of accreting SMBHs in local (D < 200 Mpc) dwarf galaxies. Cleaning our sample from X-ray background sources, X-ray binaries, and ultraluminous X-ray sources, we identify 74 active galactic nucleus (AGN)–dwarf galaxy pairs. Using this large and uniform sample, we derive the luminosity function of the dwarf galaxy AGN, fitting it with a power-law function and obtaining d N / d L X = (15.9 ± 2.2) × L X − 1.63 ± 0.05 . Measuring the offset between the dwarf galaxies' centroids and the X-ray sources, we find that ≈50% of the AGN are likely off-nuclear, in agreement with theoretical predictions. We compare the BH-to-stellar mass relation of our sample with the local and high-redshift relations, finding that our sources better adhere to the former, which suggests that local AGN across different mass scales undergo similar growth histories. Finally, we compare our sources with semianalytical models: while our sample's shallowness prevents distinguishing between different seeding models, we find that the data favor models that keep SMBHs in dwarf galaxies active at a moderate rate, motivating model improvement by comparison to AGN in the dwarf galaxy regime. [ABSTRACT FROM AUTHOR]

Broad absorption line (BAL) outflows are commonly detected in active galactic nuclei (AGNs), but their driving mechanism remains poorly constrained. Here, we investigate whether radiation pressure on dust can adequately explain the BAL phenomenon observed in quasars. In the framework of our AGN radiative dusty feedback scenario, we show that dust-driven outflows can reach BAL wind-like velocities (⁠|$v \sim 10^4$| km s |$^{-1}$|⁠) on galactic scales (⁠|$r \lesssim 1$| kpc). This is consistent with recent observations indicating that BAL acceleration typically occurs on scales of |$\sim 10$| pc, and that the majority of BAL outflows are located at galactocentric radii greater than |$\sim 100$| pc. We derive the outflow radial velocity profile and compute the associated outflow momentum rate and kinetic power, which are found to be in agreement with the outflow energetics measured in BAL quasars. Therefore, radiation pressure on dust may account for the observed BAL outflow dynamics and energetics. Furthermore, we consider BAL clouds/clumps (leading to a clumpy BAL flow characterized by a wide range of outflowing velocities), and we analyse how the resulting covering factors affect the shape of the absorption line profiles. We conclude that dust-driven BAL outflows may provide a significant contribution to AGN feedback on galactic scales. [ABSTRACT FROM AUTHOR]

We present rest-frame optical data of the |$z\sim 4$| submillimetre galaxy GN20 obtained with the JWST Near Infrared Spectrograph (NIRSpec) in integral field spectroscopy mode. The H |$\alpha$| emission is asymmetric and clumpy and extends over a projected distance of >15 kpc. To first order, the large-scale ionized gas kinematics are consistent with a turbulent (⁠|$\sigma \sim 90$| km s |$^{-1}$|⁠), rotating disc (⁠|$v_{\rm rot}\sim 500$| km s |$^{-1}$|⁠), congruent with previous studies of its molecular and ionized gas kinematics. However, we also find clear evidence for non-circular motions in the H |$\alpha$| kinematics. We discuss their possible connection with various scenarios, such as external perturbations, accretion, or radial flows. In the centre of GN20, we find broad-line emission (full width at half-maximum |$\sim 1000{-}2000$| km s |$^{-1}$|⁠) in the H |$\alpha$|  + [N  ii ] complex, suggestive of fast, active galactic nucleus-driven winds or, alternatively, of the broad-line region of an active black hole. Elevated values of [N  ii ]  |$\lambda 6583$| /H |$\alpha \ \gt\ 0.4$| and of the Hα equivalent width EW(H |$\alpha)\ \gt\ 6$| Å throughout large parts of GN20 suggest that feedback from the active black hole is able to photoionize the interstellar medium. Our data corroborate that GN20 offers a unique opportunity to observe key processes in the evolution of the most massive present-day galaxies acting in concert, over 12 billion years ago. [ABSTRACT FROM AUTHOR]

LSST will catalogue the light curves of up to 100 million quasars. Among these there can be |$\sim$| 100 ultra-compact massive black hole (MBH) binaries, whose gravitational waves (GWs) can be detected 5–15 yr later by LISA. Here, we assume such a LISA detection occurred, and assess whether or not its electromagnetic (EM) counterpart can be identified as a periodic quasar in archival LSST data. We use the binary's properties derived from the LISA waveform, including the evolution of its orbital frequency, its total mass, distance, and sky localization, to predict the redshift, magnitude, and historical periodicity of the quasar expected in the LSST data. We then use Monte Carlo simulations to compute the false alarm probability (FAP), i.e. the number of quasars in the LSST catalogue matching these properties by chance, based on the (extrapolated) quasar luminosity function, the cadence of LSST, and intrinsic 'damped random walk' quasar variability. We analyse four fiducial LISA binaries, with masses and redshifts of |$(M_{\rm bin}/{\rm M_{\odot }},z) = (3\times 10^5,0.3)$|⁠ , |$(3\times 10^6,0.3)$|⁠ , |$(10^7,0.3)$|⁠ , and |$(10^7,1)$|⁠. While noise and aliasing due to LSST's cadence produces false periodicities by chance, we find that the frequency chirp of the LISA source during the LSST observations washes out these noise peaks and allows the genuine source to stand out in appropriately scaled Lomb–Scargle periodograms. We find that all four fiducial binaries can be uniquely identified, with |${\rm FAP}\lt 10^{-5}$|⁠ , a week or more before merger. This should enable follow-up EM observations targeting individual EM counterparts during their inspiral stage. [ABSTRACT FROM AUTHOR]

We present the analysis of over 3000 red- Herschel sources (⁠|$S_{\mathrm{250\, \mu m}}\lt S_{\mathrm{350\, \mu m}}\lt S_{\mathrm{500\, \mu m} }$|⁠) using public data from the ALMA archive and the Herschel -ATLAS survey. This represents the largest sample of red- Herschel sources with interferometric follow-up observations to date. The high ALMA angular resolution and sensitivity (⁠|$\theta _{\rm FWHM}\sim$| 1 arcsec; |$\sigma _{1.3\mathrm{\, mm}}\sim 0.17$|  mJy beam |$^{-1}$|⁠) allow us to classify the sample into individual sources, multiple systems, and potential lenses and/or close mergers. Interestingly, even at this high angular resolution, 73 per cent of our detections are single systems, suggesting that most of these galaxies are isolated and/or post-merger galaxies. For the remaining detections, 20 per cent are classified as multiple systems, 5 per cent as lenses and/or mergers, and 2 per cent as low- z galaxies or active galactic nuclei. Combining the Herschel /SPIRE and ALMA photometry, these galaxies are found to be extreme and massive systems with a median star formation rate of |$\sim$| 1500  |$\mathrm{M_{\odot }\, yr^{-1}}$| and molecular gas mass of |$M_{\mathrm{gas}}\sim 10^{11}$|   |$\mathrm{M_{\odot }}$|⁠. The median redshift of individual sources is |$z\approx 2.8$|⁠ , while the likely lensed systems are at |$z\approx 3.3$|⁠ , with redshift distributions extending to |$z\sim 6$|⁠. Our results suggest a common star formation mode for extreme galaxies across cosmic time, likely triggered by close interactions or disc-instabilities, and with short depletion times consistent with the starburst-type population. Moreover, all galaxies with |$S_{\mathrm{1.3mm}}\ge 13$|  mJy are gravitationally amplified which, similar to the established |$S_{500\mathrm{ \, \mu m}}\gt 100$|  mJy threshold, can be used as a simple criterion to identify gravitationally lensed galaxies. [ABSTRACT FROM AUTHOR]

We present a deep X-Shooter rest-frame ultraviolet (UV) to optical spectral analysis of the heavily reddened quasar, ULASJ2315+0143 at |$z=2.566$|⁠ , known to reside in a major-merger host galaxy. The rest-frame optical is best fit by a dust-reddened quasar (E (B – V) |$^{\rm QSO}= 1.55$|⁠) with black-hole mass |$\rm log_{10}(H\beta , M{\small BH} [{\rm M}_{\odot }]) = 10.26 \pm 0.05$|⁠ , bolometric luminosity |$\rm L_{Bol}$|  = |$\rm 10^{48.16}\, erg\,\,s^{-1}$| and Eddington-scaled accretion rate log |$_{10}(\rm \lambda _{Edd}) = -0.19$|⁠. We find remarkable similarities between ULASJ2315+0143 and the high-redshift little red dots (LRDs). The rest-frame UV cannot be explained by a dusty quasar component alone and requires an additional blue component consistent with either a star-forming host galaxy or scattered AGN light. We detect broad high-ionization emission lines in the rest-UV, supporting the scattered light interpretation for the UV excess. The scattering fraction represents just 0.05  per cent of the total luminosity of ULASJ2315+0143 . Analysis of the mid-infrared SED suggests an absence of hot dust on torus-scales similar to what is observed for LRDs. The obscuring medium is therefore likely on galaxy scales. We detect narrow, blueshifted associated absorption-line systems in C  iv , N  v , Si  iv , and Si  iii. There is evidence for significant high-velocity (>1000  |$\rm km\, s^{-1}$|⁠) outflows in both the broad- and narrow-line regions as traced by C  iv and [O  iii ] emission. The kinetic power of the [O  iii ] wind is |$\dot{\epsilon }_{k}^{ion} = 10^{44.61} \rm erg\, s^{-1} \sim 0.001\, L_{Bol}$|⁠. ULASJ2315+0143 is likely in an important transition phase where star formation, black-hole accretion and multiphase gas flows are simultaneously occurring. [ABSTRACT FROM AUTHOR]

We derive a mean attenuation curve out to the rest-frame extreme ultraviolet (EUV) for 'BAL dust' – the dust causing the additional extinction of active galactic nuclei (AGNs) with broad absorption lines (BALQSOs). In contrast to the normal, relatively flat, mean AGN attenuation curve, BAL dust is well fit by a steeply rising, SMC-like curve. We confirm the shape of the theoretical Weingartner & Draine SMC curve out to 700 Angstroms but the drop in attenuation at still shorter wavelengths is less than predicted. The similar SMC-like attenuation curve for low-ionization BALQSOs (LoBALs) does not support the idea that they are an early phase in the life of an AGN when it is breaking out of a cocoon of star-forming dust. Although the attenuation is only |$E(B - V) \sim 0.03\!-\!0.05$| in the optical, it rises to one magnitude in the EUV, which is an optimum value for radiative acceleration of dusty gas. Because the spectral energy distribution of AGNs peaks in the EUV, the force on the dust dominates the acceleration of BAL gas. Although the shape of the attenuation curve for LoBALs is similar to the shape for HiBALs, the LoBALs on average show negative attenuation in the optical. This is naturally explained if there is more light scattered into our line of sight in LoBALs compared with non-BALQSOs. We suggest that this and partial covering are causes when attenuation curves appear to be steeper in the UV than an SMC curve. [ABSTRACT FROM AUTHOR]

Context. ESO 141-G55 is a nearby X-ray bright broad-line Seyfert 1 (BLS1) that has been classified as a bare active galactic nucleus (AGN) due to a lack of warm absorption along its line of sight, providing an unhampered view into its disc-corona system. Aims. We aim to probe its disc-corona system thanks to the first simultaneous XMM-Newton and NuSTAR observation obtained October 1–2, 2022. Methods. We carried out an X-ray broadband spectral analysis to determine the dominant process(es) at work as well as a spectral energy distribution (SED) analysis to determine the disc-corona properties. Results. The simultaneous broadband X-ray spectrum of ESO 141-G55 is characterised by the presence of a prominent smooth soft X-ray excess, a broad Fe Kα emission line, and a significant Compton hump. The high-resolution reflection grating spectrometer spectra confirmed the lack of intrinsic warm-absorbing gas along our line of sight in the AGN rest frame, verifying that it is still in a bare state. However, soft X-ray emission lines were observed, indicating substantial warm gas out of our line of sight. The intermediate inclination of the disc-corona system (∼43°) may offer us a favourable configuration to observe ultra-fast outflows from the disc, but none were found in this 2022 observation, contrary to a previous 2007 XMM-Newton one. We ruled out relativistic reflection alone on a standard disc based on the X-ray broadband analysis, while a combination of soft and hard Comptonisation by a warm and hot corona (RELAGN) plus relativistic reflection (REFLKERRD) reproduces the ESO 141-G55 SED quite well. The hot corona temperature is very hot, ∼140 keV, and much higher than about 80% of AGNs, whereas the warm corona temperature, ∼0.3 keV, is similar to the values found in other sub-Eddington AGNs. ESO 141-G55 is accreting at a moderate Eddington accretion rate (∼10–20%). Conclusions. Our analysis points to a significant contribution of an optically thick warm corona to both the soft X-ray and UV emission in ESO 141-G55, adding to the growing evidence that the accretion of AGNs (even at a moderate accretion rate) appears to deviate from standard disc theory. [ABSTRACT FROM AUTHOR]

Circumnuclear star formation (SF) is generally seen in galaxies hosting active galactic nuclei (AGN); however, the connection between the AGN activity and SF in them is less well understood. To explore this connection on scales of a few tens of parsecs to a few tens of kiloparsecs and larger, we carried out an investigation of SF in seven Seyfert-type AGN and one low-ionization nuclear emission-line region galaxy, using observations with the Ultraviolet Imaging Telescope on board AstroSat in the near-ultraviolet (2000–3000 Å) and far-ultraviolet (1300−1800 Å) bands. A total of 1742 star-forming regions were identified, having size scales of 0.010–63.642 kpc2. Considering all the galaxies, we found a positive correlation between their total surface density of SF (ΣSFR) and extinction. For five galaxies, namely NGC 1365, NGC 4051, NGC 4321, NGC 5033, and NGC 6814, we found a gradual decrease of both extinction and ΣSFR from the centre to the outer regions. Four sources are found to lie in the main sequence of star-forming galaxies, and the other four lie away from it. We found the ratio of the star formation rate (SFR) in the nuclear region to the total SFR to be positively correlated with the Eddington ratio. This points to the influence of AGN in enhancing the SF characteristics of the hosts. However, the impact is dominant only in the central nuclear region and has no significant effect on the larger scales probed in this work. [ABSTRACT FROM AUTHOR]

Outflows driven by active galactic nuclei (AGNs) are seen in numerous compact sources; however, it has remained unclear how to distinguish between the driving mechanisms, such as winds and jets. Therefore, our study aims to offer observational insights from simulations to aid in this distinction. Specifically, in this paper, we investigate the evolution of wide-angled moderately relativistic magnetized winds and analyse their non-thermal radio emission and polarization properties. We find that the evolution of winds varies depending on factors such as power, density, and opening angle, which in turn influence their observable characteristics. Additionally, different viewing angles can lead to varying observations. Furthermore, we note distinctions in the evolution of winds compared to jets, resulting in disparities in their observable features. Jets typically exhibit a thin spine and hotspot(s). Winds manifest broader spines or an 'hourglass-shaped' bright emission in the cocoon, which are capped by bright arcs. Both display high polarization coinciding with the bright spine and hotspots/arcs, although these regions are relatively compact and localized in jets when compared to winds. We emphasize the importance of high resolution, as we demonstrate that emission features from both jets and winds can become indistinguishable at lower resolutions. The distribution of polarization is largely unaffected by resolution, though lower polarization becomes more noticeable when the resolution is decreased. [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]

Small-scale winds driven from accretion discs surrounding active galactic nuclei (AGN) are expected to launch kpc-scale outflows into their host galaxies. However, the ways in which the structure of the interstellar medium (ISM) affects the multiphase content and impact of the outflow remain uncertain. We present a series of numerical experiments featuring a realistic small-scale AGN wind with velocity |$5\times 10^3 \!-\! 10^4\rm {\ km\ s^{-1}}$| interacting with an isolated galaxy disc with a manually controlled clumpy ISM, followed at sub-pc resolution. Our simulations are performed with arepo and probe a wide range of AGN luminosities (⁠|$L_{\rm {AGN}}{=} 10^{43-47}\rm {\ erg\ s^{-1}}$|⁠) and ISM substructures. In homogeneous discs, the AGN wind sweeps up an outflowing, cooling shell, where the emerging cold phase dominates the mass and kinetic energy budgets, reaching a momentum flux |$\dot{p} \approx 7\ L/c$|⁠. However, when the ISM is clumpy, outflow properties are profoundly different. They contain small, long-lived (⁠|$\gtrsim 5\ \rm {Myr}$|⁠), cold (⁠|$T{\lesssim }10^{4.5}{\rm {\ K}}$|⁠) cloudlets entrained in the faster, hot outflow phase, which are only present in the outflow if radiative cooling is included in the simulation. While the cold phase dominates the mass of the outflow, most of the kinetic luminosity is now carried by a tenuous, hot phase with |$T \gtrsim 10^7 \, \rm K$|⁠. While the hot phases reach momentum fluxes |$\dot{p} \approx (1 - 5)\ L/c$|⁠ , energy-driven bubbles couple to the cold phase inefficiently, producing modest momentum fluxes |$\dot{p} \lesssim L/c$| in the fast-outflowing cold gas. These low momentum fluxes could lead to the outflows being misclassified as momentum-driven using common observational diagnostics. We also show predictions for scaling relations between outflow properties and AGN luminosity and discuss the challenges in constraining outflow driving mechanisms and kinetic coupling efficiencies using observed quantities. [ABSTRACT FROM AUTHOR]

We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in the Hubble Space Telescope/Cosmic Origins Spectrograph spectra, both during the campaign and in other epochs extending over 14 yr. We conclude that, while the narrow absorption outflow system (at −3750 km s−1 with FWHM = 177 km s−1) responds to the variations of the UV continuum as modified by the X-ray obscurer, its total column density (log N H = 19.5 − 0.13 + 0.61 cm−2) did not change across all epochs. The adjusted ionization parameter (scaled with respect to the variations in the hydrogen-ionizing continuum flux) is log U H = −1.0 − 0.3 + 0.1 . The outflow is located at a distance smaller than 38 pc from the central source, which implies a hydrogen density of n H > 3000 cm−3. The absorption outflow system only covers the continuum emission source and not the broad emission line region, which suggests that its transverse size is small (< 1016 cm), with potential cloud geometries ranging from spherical to elongated along the line of sight. [ABSTRACT FROM AUTHOR]

We report the identification of an extremely rare and peculiar set of irregular radio sources, termed "STROMERSs" (STRange and Odd Morphology Extragalactic Radio Sources).ingThe irregular radio sources with very anomalous morphologies that make them exceptionally different from all the known classes and subclasses of irregular radio sources are detected as STROMERSs. A thorough search for this class of sources from the Very Large Array (VLA) Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) gave a total of nine such candidates. We checked the corresponding morphology of the identified sources in other frequency surveys. We found a detectable radio emission for all of the nine sources in the NRAO VLA Sky Survey (NVSS) at 1.4 GHz and in the TIFR GMRT Sky Survey (TGSS) at 150 MHz, while the same was found for only three sources in the Westerbork Northern Sky Survey (WENSS) at 625 MHz. However, the strange morphology was not found in all of those other survey images. We also characterized the sources with their corresponding physical parameters like optical counterpart, size, spectral index, and radio luminosity. ingThe estimated spectral values of the sources indicated that the STROMERSs were most likely radio galaxies. The presence of any nearby galaxy clusters for the STROMERSs was also checked. [ABSTRACT FROM AUTHOR]

For the first time, a calibration between the He  i |$\lambda 5876$| /H  |$\beta$| emission line ratio and the helium abundance y = 12 + log(He/H) for Narrow line regions of Seyfert 2 Active Galactic Nuclei is proposed. In this context, observational data (taken from the SDSS-DR15 and from the literature) and direct abundance estimates (via the |$T_{\rm e}$| -method) for a sample of 65 local (⁠|$z \: \lt \: 0.2$|⁠) Seyfert 2 nuclei are considered. The resulting calibration estimates the y abundance with an average uncertainty of 0.02 dex. Applying our calibration to spectroscopic data containing only strong emission lines, it yields a helium abundance distribution similar to that obtained via the |$T_{\rm e}$| -method. Some cautions must be considered to apply our calibration for Seyfert 2 nuclei with high values of electron temperature (⁠|${\gtrsim} 20\, 000$|  K) or ionization parameter (⁠|$\log U \ \gt\ {-}2.0$|⁠). [ABSTRACT FROM AUTHOR]

Ultraviolet (UV)/optical variability in quasars is a well-observed phenomenon, yet its primeval origins remain unclear. This study investigates whether the accretion disc turbulence, which is responsible for UV/optical variability, is influenced by the close environment of the accretion by analysing the correlation between variability and infrared emission for two luminous quasar samples from the Sloan Digital Sky Survey (SDSS). The first sample includes light curves from SDSS, Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), and Zwicky Transient Facility g -band photometry, while the second sample utilizes SDSS Stripe 82 g -band light curves. We explore the correlation between the g -band excess variance (⁠|$\sigma _{\mathrm{ rms}}$|⁠) and the wavelength-dependent infrared covering factor (⁠|$L_{\rm IR}(\lambda)/L_{\rm bol}$|⁠), controlling for the effects of redshift, luminosity, and black hole mass. An anticorrelation between two variables is observed in both samples, which is strongest at wavelengths of 2–3  |$\rm{\mu m}$| but gradually weakens towards longer wavelength. This suggests the equatorial dusty torus (which dominates near-infrared emission) plays a significant role in influencing the UV/optical variability, while the cooler polar dust (which contributes significantly to mid-infrared emission) does not. The findings indicate that quasar variability may be connected to the physical conditions within the dusty torus which feeds the accretion, and support the notion that the close environment of the accretion plays an important role in regulating the accretion disc turbulence. [ABSTRACT FROM AUTHOR]

An increasing number of exoplanets have been discovered in the Milky Way galaxy, which is also known to harbour a super-massive black hole (Sagittarius A*) at its centre. Here, we investigate how the central black hole (BH) activity may affect the evolution of exoplanets in our Galaxy. Accreting BHs emit high-energy radiation – extreme ultraviolet and X-rays – which can lead to XUV photoevaporation of the planetary atmospheres. We evaluate the atmospheric mass-loss using both theoretical estimates of the BH radiative output and observational constraints on the past activity history of Sgr A*. The resulting mass-loss is analysed as a function of the galactocentric distance. For the first time, we compute the exoplanet atmospheric evolution under BH irradiation by explicitly including the temporal evolution of the central luminosity output (i.e. the BH activity history). We obtain that Sgr A* could have a major impact on exoplanets located in the inner region of the Galaxy (e.g. Galactic bulge); a significant fraction of the atmospheric mass can be removed by BH irradiation; and in extreme cases, the initial atmosphere may be completely stripped away. Such mass-loss can have important consequences on the atmospheric chemistry and potential biological evolution. We discuss the physical implications for planetary habitability, and we also briefly consider the case of stellar-mass BHs. Overall, accreting black holes may play a significant role in the evolution of exoplanets in our Galaxy across cosmic time. [ABSTRACT FROM AUTHOR]

The observation data of blazar 1ES 1426+42.8 were obtained using the 1.02 m optical telescope of Yunnan Observatories during 2021 to 2023. Intraday variability (IDV) is detected on seven nights. We use the turbulent model to investigate the mechanism of IDV in 1ES 1426+42.8. The fitting light curves match the actual IDV curves well. Using this model, we obtain the parameters such as the size of turbulent cells and the width of pulses in the jet. A possible short-lived quasi-periodic oscillation (QPO) of |$58.55 \pm 8.09$| min was detected on 2022 April 26 whose light curve exhibits eight cycles at |$\gt 3\sigma$| global significance and confirmed by several different techniques. Through a more detailed analysis of the light curve of this night, we find that the period is shortened from 54.23 min (⁠|$4\sigma$|⁠) to 29.71 min (⁠|$3\sigma$|⁠). The possible QPO and period shortening phenomenon are best explained by the processes of magnetic reconnections. [ABSTRACT FROM AUTHOR]

We present new ALMA observations of CO, CN, CS, HCN, and HCO |$^{+}$| absorption seen against the bright and compact radio continuum sources of eight galaxies. Combined with archival observations, they reveal two distinct populations of molecular clouds, which we identify by combining CO emission and absorption profiles to unambiguously reveal each cloud's direction of motion and likely location. In galaxy discs, we see clouds with low velocity dispersions, low line-of-sight velocities, and a lack of any systemic inflow or outflow. In galactic cores, we find high velocity dispersion clouds inflowing at up to 550 km s−1. This provides observational evidence in favour of cold accretion on to galactic centres, which likely contributes to the fuelling of active galactic nuclei. We also see a wide range in the CO(2-1)/CO(1-0) ratios of the absorption lines. This is likely the combined effect of hierarchical substructure within the molecular clouds and continuum sources which vary in size with frequency. [ABSTRACT FROM AUTHOR]

Understanding star formation in galaxies requires resolving the physical scale on which star formation often occurs: the scale of star clusters. We present a multiwavelength, eight-parsec resolution study of star formation in the circumnuclear star cluster and molecular gas rings of the early-type spiral NGC 1386. The cluster ring formed simultaneously ∼4 Myr ago. The clusters have similar properties in terms of mass and star formation rate, resembling those of H  ii regions in the Milky Way disc. The molecular CO gas resolves into long filaments, which define a secondary ring detached from the cluster ring. Most clusters are in CO voids. Their separation with respect to the CO filaments is reminiscent of that seen in galaxy spiral arms. By analogy, we propose that a density wave through the disc of this galaxy may have produced this gap in the central kpc. The CO filaments fragment into strings of dense, unresolved clouds with no evidence of a stellar counterpart. These clouds may be the sites of a future population of clusters in the ring. The free-fall time of these clouds, ∼10 Myr, is close to the orbital time of the CO ring. This coincidence could lead to a synchronous bursting ring, as is the case for the current ring. The inward spiralling morphology of the CO filaments and co-spatiality with equivalent kpc-scale dust filaments are suggestive of their role as matter carriers from the galaxy outskirts to feed the molecular ring and a moderately active nucleus. [ABSTRACT FROM AUTHOR]

In theoretical models of galaxy evolution, black hole feedback is a necessary ingredient in order to explain the observed exponential decline in number density of massive galaxies. Most contemporary black hole feedback models in cosmological simulations rely on a constant radiative efficiency (usually |$\eta \sim 0.1$|⁠) at all black hole accretion rates. We present the obsidian subgrid model, a synthesis model for the spin-dependent radiative efficiencies of three physical accretion rate regimes, i.e. |$\eta = \eta (j, \dot{M}_\mathrm{acc})$|⁠ , for use in large-volume cosmological simulations. The three regimes include: an advection-dominated accretion flow (⁠|$\dot{M}_\mathrm{acc}\lt 0.03\, \dot{M}_\mathrm{Edd}$|⁠), a quasar-like mode (⁠|$0.03 \lt \dot{M}_\mathrm{acc}/ \dot{M}_\mathrm{Edd}\lt 0.3$|⁠), and a slim disc mode (⁠|$\dot{M}_\mathrm{acc}\gt 0.3\, \dot{M}_\mathrm{Edd}$|⁠). Additionally, we include a large-scale powerful jet at low accretion rates. The black hole feedback model we present is a kinetic model that prescribes mass loadings but could be used in thermal models directly using the radiative efficiency. We implement the obsidian model into the simba galaxy evolution model to determine if it is possible to reproduce galaxy populations successfully, and provide a first calibration for further study. Using a |$2\times 1024^3$| particle cosmological simulation in a |$(150\, \mathrm{cMpc})^3$| volume, we found that the model is successful in reproducing the galaxy stellar mass function, black hole mass–stellar mass relationship, and stellar mass–halo mass relationship. Moving forward, this model opens new avenues for exploration of the impact of black hole feedback on galactic environments. [ABSTRACT FROM AUTHOR]

Reprocessed X-ray radiation from active galactic nuclei (AGN) carries important information about the properties of the circumnuclear material around the black hole. The X-ray photons travel from the very centre of the system and interact with that material often producing strong emission lines. The |$\rm {Fe\, K\alpha }$| Compton shoulder (CS) is formed by fluorescent |$\rm {Fe\, K\alpha }$| photons that perform Compton scatterings with the intercepting material and lose energy to form the distinct shoulder shape. In this work, we use the ray-tracing code RefleX to explore how the physical properties of the medium, as well as its geometry, affect the shape of the CS. We start by running simulations using a simple toroidal reflector, to test the effect of the metal composition, metallicity, column density, dust presence and velocity on the |$\rm {Fe\, K\alpha }$| line, and its CS. We confirm that the shape of the CS is sensitive to the optical depth of the intercepting medium, which can be regulated by either changing the metal composition or the line-of-sight column density of the circumnuclear material. Next, we create a series of models, which feature different geometrical configurations of dust and gas, and explore how the CS is affected by such configurations finding that components that can regulate the line-of-sight column density affect the |$\rm {Fe\, K\alpha }$| and its CS. Finally, we test whether observatories such as the recently launched XRISM and future Athena will make the CS a useful spectral feature of nearby AGN, by applying specific models on simulated spectra of the Circinus galaxy. The CS has the potential to be used to help constrain properties of the circumnuclear material yet with some limitations. [ABSTRACT FROM AUTHOR]

The Fermi -LAT has detected more than 7000 |$\gamma$| -ray sources which show emission above 50 MeV of which more than half are associated with blazars. However, the Fourth Fermi -LAT catalogue (4FGL-DR4) lists 1625 of these as blazar candidates of uncertain type. Increasing the number of classified Fermi -LAT sources is important for improving our understanding of extragalactic |$\gamma$| -ray sources and can be used to search for new classes of very high energy sources. We report on the optical spectroscopy of twelve blazar candidates with hard photon indices included in the Third Catalogue of Hard Fermi -LAT Sources during 2016 and 2017 using the SAAO 1.9-m telescope. We classify all the sources observed as BL Lac objects, and determine the potential spectroscopic redshift for seven of them. [ABSTRACT FROM AUTHOR]

The jets of radio AGN provide one of the most important forms of active galactic nuclei (AGN) feedback, yet considerable uncertainties remain about how they are triggered. Since the molecular gas reservoirs of the host galaxies can supply key information about the dominant triggering mechanism(s), here we present Atacama Large Millimeter/sub-millimeter Array CO(1-0) observations of a complete sample of 29 powerful radio AGN (⁠|$P_{1.4\,{\rm GHz}} \gt 10^{25}$|  W Hz |$^{-1}$| and |$0.05 \lt z \lt 0.3$|⁠) with an angular resolution of about 2–3 arcsec (corresponding to 2–8 kpc). We detect molecular gas with masses in the range |$10^{8.9} \lt M_{{\rm H}_2} \lt 10^{10.2}$| M |$_\odot$| in the early-type host galaxies of ten targets, while for the other 19 sources, we derive upper limits. The detection rate of objects with such large molecular masses – |$34\pm 9$|  per cent – is higher than in the general population of non-active early-type galaxies (ETGs: |$\lt $| 10 per cent). The kinematics of the molecular gas are dominated in most cases by rotating disc-like structures, with diameters up to 25 kpc. Compared with the results for samples of quiescent ETG in the literature, we find a larger fraction of more massive, more extended and less settled molecular gas structures. In most of the CO-detected sources, the results are consistent with triggering of the AGN as the gas settles following a merger or close encounter with a gas-rich companion. However, in a minority of objects at the centres of rich clusters of galaxies, the accretion of gas cooling from the hot X-ray haloes is a plausible alternative to galaxy interactions as a triggering mechanism. [ABSTRACT FROM AUTHOR]

SDSS J083942.11+380526.3 (⁠|$z=2.315$|⁠) is an iron low-ionization broad absorption lines quasar that exhibits visible Balmer absorption lines (H  |$\alpha$|⁠), implying a significant |$n=2$| population. The quasar also shows an array of absorption lines, including O  i , Ni  ii , Fe  ii , Mg  ii , Al  iii  to C  iv , and N v. The high-ionization absorption lines such as C  iv and Si  iv are revealed by slightly blueshifted broad absorption lines troughs. The resonance doublets such as Mg  ii and Al  iii are saturated but did not reached zero intensity which indicates that the broad-line region (BLR) is partially covered. Overall, however, the absorption is predominantly from low-ionization Fe  ii lines, emitted from ground and excited states up to at least 3.814 eV. This implies that the absorbing gas spans the hydrogen ionization front and extends into the partially ionized zone where neutral hydrogen is certainly present. Notably, the hydrogen line spectrum of the quasar shows no signature of expected Ly  |$\alpha$| absorption. Instead, the line spectrum shows an unusual Ly  |$\alpha$| emission characterized by a fully filled emission line spectrum which is a composite of a strong narrow core superposed on a weak broad base. Taking into account the effect of partial covering to BLR, we have extracted a strong Damped Ly α systems (DLA) trough in Ly  |$\alpha$| emission region. To fit the spectrum, we performed photoionized model calculations and compared them to the observations. We found that photoionization modelling using cloudy can successfully reproduce the main characteristics of the quasar spectrum, and the predicted neutral hydrogen column density arising from the clouds responsible for the low-ionization absorption provides a good match to the extracted DLA trough. This indicates that both the DLA and the low-ionization absorption arise from the same medium that is roughly collocated with the dusty torus. [ABSTRACT FROM AUTHOR]

One of the most promising methods to measure the spin of an accreting black hole is fitting the broad iron K |$\alpha$| line in the X-ray spectrum. The line profile also depends on the geometry of the hard X-ray emitting corona. To put constraints on the black hole spin and corona geometry, it is essential to understand how do they affect the iron K |$\alpha$| line emissivity profile. In this work, we present calculations of the illumination and the iron K |$\alpha$| emissivity profiles performed with the Monte Carlo GR radiative transfer code monk. We focus on distinction between the illumination and emissivity profiles, which is in most previous studies neglected. We show that especially for the case of black hole X-ray binaries (BHXRBs), the difference is very large. For active galactic nuclei (AGNs), the emissivity profile has a more similar shape as the illumination profile, but it is notably steeper in the innermost region within a few gravitational radii. We find out that the different behaviour between AGN and BHXRB discs is due to the different energy spectra of the illuminating radiation. This suggests that the emissivity profile of the iron K |$\alpha$| line cannot be determined by black hole spin and corona geometry alone and the energy spectrum of the illuminating radiation has to be taken into account. We also examined the effect of including the self-irradiation, and find it to be more important than the corona emission in BHXRBs. [ABSTRACT FROM AUTHOR]

In this work, we explore the connection of three jetted |$\gamma -$| loud AGNs classes: Compact steep-spectrum sources (CSS), Narrow-line Seyfert 1 (NLS1), and flat-spectrum radio quasars, through the modelling of the spectral energy distribution (SED). We selected two sources identified as CSS/NLS1 hybrids, PKS 2004-440 and 3C 286. Additionally, we included the source PKS 0440-00, initially classified as an FSRQ in the first Fermi -LAT catalogue, but recently reclassified as an NLS1. We present the results of their broadband SED modelling using a one-zone leptonic synchrotron-self Compton (SSC) + external Compton (EC) model. By exploring the parameter space and investigating the disc–jet connection in these sources, we analyse their classification in a model-dependent way. Our findings reveal that modeling PKS 2004-447 at relatively large angles, as expected for CSS, results in an SSC-dominated inverse Compton emission. In contrast, at low-observing angles, the inverse Compton emission is dominated by external photon fields. Both scenarios result in a jet with a low-radiative power. For 3C 286, we found that using a one-zone model limits the jet viewing angle to |$\sim 7^{\circ }$|⁠ , mainly due to its impact on the |$\gamma$| -ray emission. Our model results show a magnetically dominated jet, consistent with |$\gamma$| -CSS sources. Our results suggest that PKS 0440-00, can be classified as a powerful |$\gamma -$| NLS1, characterized by high accretion power and a jet dominated by bulk motion, similar to FSRQs. [ABSTRACT FROM AUTHOR]

Broad absorption line (BAL) quasars are characterized by gas clouds that absorb flux at the wavelength of common quasar spectral features, although blueshifted by velocities that can exceed |$0.1c$|⁠. BAL features are interesting as signatures of significant feedback, yet they can also compromise cosmological studies with quasars by distorting the shape of the most prominent quasar emission lines, impacting redshift accuracy and measurements of the matter density distribution traced by the Lyman |$\alpha$| forest. We present a catalogue of BAL quasars discovered in the Dark Energy Spectroscopic Instrument (DESI) survey Early Data Release, which were observed as part of DESI Survey Validation, as well as the first two months of the main survey. We describe our method to automatically identify BAL quasars in DESI data, the quantities we measure for each BAL, and investigate the completeness and purity of this method with mock DESI observations. We mask the wavelengths of the BAL features and re-evaluate each BAL quasar redshift, finding new redshifts which are |$243\, {\rm km}\, {\rm s}^{-1}$| smaller on average for the BAL quasar sample. These new, more accurate redshifts are important to obtain the best measurements of quasar clustering, especially at small scales. Finally, we present some spectra of rarer classes of BALs that illustrate the potential of DESI data to identify such populations for further study. [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]

The gamma-ray emitting narrow-line Seyfert 1 galaxies are a unique class of objects that launch powerful jets from relatively lower-mass black hole systems compared to the Blazars. However, the black hole masses estimated from the total flux spectrum suffer from the projection effect, making the mass measurement highly uncertain. The polarized spectrum provides a unique view of the central engine through scattered light. We performed spectropolarimetric observations of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H0323 + 342 using SPOL/MMT. The degree of polarization and polarization angle are 0.122 |$\pm$| 0.040 per cent and 142 |$\pm$| 9 degrees, while the H |$\alpha$| line is polarized at 0.265 |$\pm$| 0.280 per cent. We decomposed the total flux spectrum and estimated broad H |$\alpha$| full width at half maximum of 1015 km s |$^{-1}$| . The polarized flux spectrum shows a broadening similar to the total flux spectrum, with a broadening ratio of 1.22. The Monte Carlo radiative transfer code 'STOKES' applied to the data provides the best fit for a small viewing angle of 9–24 deg and a small optical depth ratio between the polar and the equatorial scatters. A thick broad-line region with significant scale height can explain a similar broadening of the polarized spectrum compared to the total flux spectrum with a small viewing angle. [ABSTRACT FROM AUTHOR]

High precision mapping of H |$_{2}$| O megamaser emission from active galaxies has revealed more than a dozen Keplerian H |$_{2}$| O maser discs, which enable a |$\sim$| 4 per cent uncertainty estimate of the Hubble constant as well as providing accurate masses for the central black holes. These discs often have well-defined inner and outer boundaries of maser emission on sub-parsec scales. In order to better understand the physical conditions that determine the inner and outer radii of a maser disc, we examine the distributions of gas density and X-ray heating rate in a warped molecular disc described by a power-law surface density profile. For a suitable choice of the disc mass, we find that the outer radius |$R_{\rm out}$| of the maser disc predicted from our model can match the observed value, with |$R_{\rm out}$| mainly determined by the maximum heating rate or the minimum density for efficient maser action, depending on the combination of the Eddington ratio, black hole mass, and disc mass. Our analysis also indicates that the inner radius for maser action is comparable to the dust sublimation radius, suggesting that dust may play a role in determining the inner radius of a maser disc. Finally, our model predicts that H |$_{2}$| O gigamaser discs could exist at the centres of high-z quasars, with disc sizes of |$\gtrsim 10-30$| pc. [ABSTRACT FROM AUTHOR]

We adopt a Bayesian X-ray spectral approach to investigate the accretion properties of unobscured (⁠|$20\lt \log (N_{\rm H}/{\rm cm}^{-2}\lt 22$|⁠) and obscured (⁠|$22\lt \log (N_{\rm H}/{\rm cm}^{-2}\lt 24$|⁠) active galactic nuclei (AGNs) to shed light on the orientation versus evolution scenarios for the origin of the obscuring material. For a sample of 3882 X-ray-selected AGN from the Chandra COSMOS Legacy, AEGIS, and CDFS extragalactic surveys, we constrain their stellar masses, |$M_\star$|⁠ , intrinsic X-ray luminosities, |$L_{\rm X}$|⁠ , obscuring column densities, |$N_{\rm H}$|⁠ , and specific accretion rates |$\lambda \propto L_{\rm X}/M_\star$|⁠. By combining these observables within a Bayesian non-parametric approach, we infer, for the first time, the specific accretion rate distribution (SARD) of obscured and unobscured AGN to |$z\approx 3$|⁠ , i.e. the probability of a galaxy with mass |$M_\star$| at redshift z hosting an AGN with column density |$N_{\rm H}$| and specific accretion rate |$\lambda$|⁠. Our findings indicate that (1) both obscured and unobscured SARDs share similar shapes, shifting towards higher accretion rates with redshift, (2) unobscured SARDs exhibit a systematic offset towards higher |$\lambda$| compared to obscured SARD for all redshift intervals, (3) the obscured AGN fraction declines sharply at |$\log \lambda _{\rm break} \sim -2$| for |$z \lt 0.5$|⁠ , but shifts to higher |$\lambda$| values with increasing redshift, (4) the incidence of AGN within the theoretically unstable blow-out region of the |$\lambda -N_{\rm H}$| plane increases with redshift. These observations provide compelling evidence for AGN 'downsizing' and radiation-regulated nuclear-scale obscuration with an increasing host galaxy contribution towards higher redshifts. [ABSTRACT FROM AUTHOR]

Jetted active galactic nuclei (AGN) hosting extended photoionized nebulae provide us with a unique view of the timescales associated with AGN activity. Here, we present a new green bean galaxy at z = 0.304458 ± 0.000007 with large-scale jet-induced radio emission. The spectral energy distributions of the radio components show steep spectral indices (α = −0.85 to −0.92 for the extended regions, and α = −1.02 for the faint radio core), and spectral age modeling of the extended radio emission indicates that the lobes are >6 Myr old. It is unclear whether the jet is active, or is a remnant with an off-time of 2–3 Myr. Several detached clouds lie around the host galaxy up to 37.8 kpc away from the nucleus, and their ionization profile indicates a decline (∼2 dex) in the AGN ionizing photon production over the past ∼0.15 Myr. Furthermore, we measure a blueshift for one of the clouds that is spatially coincident with the path of the radio jet. The cloud is likely illuminated by the photoionizing AGN, and potentially underwent an interaction with the relativistic jet. Our multiwavelength analysis suggests that RGB1 was in a phase of jet production prior to the radiatively efficient accretion phase traced by the detached cloud emission. It is unclear whether RGB1 transitioned into a low-excitation radio galaxy or an inactive galaxy over the past ∼0.15 Myr, or whether the extended radio and optical emission trace distinct accretion phases that occurred in succession. [ABSTRACT FROM AUTHOR]

We present the results of seven years of multicolour photometric monitoring of a sample of 31 |$\gamma$| -ray bright blazars using the RINGO3 polarimeter on the Liverpool Telescope from 2013–2020. We explore the relationships between simultaneous observations of flux in three optical wavebands along with Fermi |$\gamma$| -ray data in order to explore the radiation mechanisms and particle populations in blazar jets. We find significant correlations between optical and |$\gamma$| -ray flux with no detectable time lag, suggesting leptonic emission processes in the jets of these sources. Furthermore, we find the spectral behaviour against optical and |$\gamma$| -ray flux for many sources is best fit logarithmically. This is suggestive of a transition between bluer-/redder-when-brighter into stable-when-brighter behaviour during high activity states; a behaviour that might be missed in poorly sampled data, resulting in apparent linear relationships. [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]

At optical/ultraviolet energies, blazars display an underlying thermal (unpolarized) contribution from the accretion disc, torus, and line-emitting regions, diluting the polarized emission from the jet-component. Optical polarimetry can be used to disentangle the thermal and non-thermal components, and place constraints on the particle populations and acceleration mechanisms responsible for the non-thermal emission. We present the results of a linear optical spectropolarimetric observing campaign of 18 blazars (six BL Lac-type objects and 12 flat-spectrum radio quasars) undertaken with the Southern African Large Telescope between 2016 and 2022. This was done to observe these systems during flaring states, as well as long-term monitoring of PKS1510-089, AP Lib, and PKS 1034-293. The observations traced the frequency dependence of the degree and angle of polarization, as well as changes in the spectral line strengths. We investigated possible correlations between the polarization and other observed characteristics for the sources. While an indication of correlation was found between the frequency dependence and the average level of polarization for some sources, a correlation was not found for the population as a whole. These results highlight that continuous observations and in-depth modelling of polarization and its frequency dependence is required to obtain a more holistic view of TeV blazars. [ABSTRACT FROM AUTHOR]

We present a systematic study of mid-infrared spectra of galaxies including star-forming galaxies and active galactic nuclei observed with JWST MIRI-MRS and NIRSpec-IFU. We focus on the relative variations of the 3.3, 6.2, 7.7, 11.3, 12.7, and 17 |$\mu$| m polycyclic aromatic hydrocarbon (PAH) features within spatially resolved regions of galaxies including NGC 3256, NGC 7469, VV 114, II Zw96, and NGC 5728. Using theoretical PAH models and extending our earlier work, we introduce a new PAH diagnostic involving the 17 |$\mu$| m PAH feature. To determine the drivers of PAH band variations in galaxies, we compare observed PAH spectral bands to predictions from theoretical PAH models. We consider extinction, dehydrogenation, and PAH size and charge as possible drivers of PAH band variations. We find a surprising uniformity in PAH size distribution among the spatially resolved regions of the galaxies studied here, with no evidence for preferential destruction of the smallest grains, contrary to earlier findings. Neither extinction nor dehydrogenation play a crucial role in setting the observed PAH bands. Instead, we find that PAH charge plays a significant role in PAH inter-band variations. We find a tight relation between PAH charge and the intensity of the radiation field as traced by the [Ne  iii ] |$/$| [Ne  ii ] maps. In agreement with recent JWST results, we find a predominance of neutral PAH molecules in the nuclei of active galaxies and their outflows. Ionized PAHs are the dominant population in star-forming galaxies. We discuss the implications of our findings for the use of PAHs as ISM tracers in high redshift galaxies. [ABSTRACT FROM AUTHOR]

Mature radio galaxies such as M87 belong to a specific subclass of active galaxies (AGN) whose evolution in time endows them with five distinguishing characteristics, including (1) low excitation emission, (2) low star formation rates, (3) high bulge stellar-velocity dispersion, (4) bright stellar nuclei, and (5) weak or nonexistent merger signatures. We show how to understand these seemingly disparate characteristics as originating from the time evolution of powerful radio quasars and describe a new model prediction that tilted accretion disks in AGN are expected to occur in bright quasars but not in other subclasses of AGN. The picture we present should be understood as the most compelling evidence for counter-rotation as a key element in feedback from accreting black holes. [ABSTRACT FROM AUTHOR]

Odd radio circles (ORCs) are mysterious rings of faint, diffuse emission recently discovered in radio surveys, some of which may be associated with galaxies in relatively dense environments. We propose that such ORCs are synchrotron emission from remnants of explosive galactic outflows, calling them OGREs, and discuss their broad-band non-thermal emission and evolution. We posit that a large amount of energy was ejected from the central galaxy in the past, creating an outgoing shock that accelerates cosmic rays. Assuming plausible values for the density, temperature and magnetic field of the ambient medium, consistency with the observed spectral index, size, and power of the ORCs requires the energy to be as high as ∼1060 erg, suggesting that their sources could be active galactic nuclei. We calculate the spectral energy distributions (SEDs) of the OGREs and their evolution, including synchrotron, inverse Compton (IC), and bremsstrahlung emission from electrons, and pion-decay emission from protons. We find that the SEDs of the younger OGREs are not greatly different from those of older ones currently observable as ORCs if radiative cooling of electrons is effective. As such younger OGREs are expected to be rarer and smaller, they may not be readily observable. However, if radiative cooling of electrons is ineffective, younger OGREs may be detectable in X-rays. [ABSTRACT FROM AUTHOR]

The nature of the interaction between active galactic nuclei (AGNs) and their host galaxies remains an unsolved question. Therefore, conducting an AGN census is valuable for AGN research. Nevertheless, a significant fraction of AGNs are obscured by their environment, which blocks UV and optical emissions due to the dusty torus surrounding the central supermassive black hole (SMBH). To overcome this challenge, mid-infrared (IR) surveys have emerged as a valuable tool for identifying obscured AGNs, as the obscured light is re-emitted in this range. With its high sensitivity, the JWST uncovered more fainter objects than previous telescopes. By applying the SED fitting, this work investigates AGN candidates in JWST Cosmic Evolution Early Release Science (CEERS) fields. We identified 42 candidates; 30 of them are classified as composites (⁠|$0.2\le f_{\text{AGN, IR}} < 0.5$|⁠), and 12 of them are AGNs (⁠|$f_{\text{AGN, IR}}\ge 0.5$|⁠). We report the AGN luminosity contributions and AGN number fractions as a function of redshift and total infrared luminosity, showing that previously reported increasing relations are not apparent in our sample due to the sample size. We also extend the previous results on ultraluminous infrared galaxies (ULIRGs, |$L_{\rm TIR}\ge 10^{12} L_{\odot }$|⁠) to less luminous AGNs, highlighting the power of JWST. [ABSTRACT FROM AUTHOR]

Radio galaxies harbouring jetted active galactic nuclei are a frequent target of very long baseline interferometry (VLBI) because they play an essential role in our exploration of how jets form and propagate. Hence, only a few have not yet been detected with VLBI; Fornax A was one of the most famous examples. Here we present the first detection of the compact core region of Fornax A with VLBI. At 8.4 GHz the faint core is consistent with an unresolved point source. We constrained its flux density to be S0 = 47.5 − 62.3 mJy and its diameter to be D0min ≤ 70 μas. The high values of the measured brightness temperature (TB ≳ 1011 K) imply that the observed radiation is of non-thermal origin, likely associated with the synchrotron emission from the active galactic nucleus. We also investigated the possibility of a second radio source being present within the field of view. Adding a second Gaussian component to the geometrical model fit does not significantly improve the quality of the fit, and we therefore, conclude that our detection corresponds to the compact core of Fornax A. Analysis of the non-trivial closure phases provides evidence for the detection of a more extended flux density, on the angular scale of ∼4000 μas. Finally, the fractional circular polarisation of the core is consistent with zero, with a conservative upper limit being mcirc ≤ 4%. [ABSTRACT FROM AUTHOR]

We present Very Long Baseline Array observations of radio continuum and OH line emission toward the OH megamaser (OHM) galaxy IRAS 01298−0744. We recover over 82% of the OH line emission seen in single-dish observations, including multiple strong OH line components and the broad shallow line profile spanning over 1000 km s−1. The OH emission spatially has four compact components, as well as diffuse emission, and the 3σ signals are distributed in a rectangular region with size of ∼40 × 30 mas. The spatial-velocity structure is complex and is consistent with that from HCN and HCO+ lines in the literature, indicating that the nuclear region of this source is likely still in the merging process characterized by intense nuclear activities. The multiple strong OH peaks are blue-shifted compared to dense millimetre-wave molecular gas tracers, but similar to optical Na I absorption. This suggests that the compact masers might be in an outflow driven by an active galactic nucleus or starburst. We have detected compact radio continuum emissions adjacent to the maser positions with a brightness temperature of around 3 × 106 K, similar to other OHM galaxies with very-long-baseline interferometry observations in the literature, which is consistent with a starburst origin. [ABSTRACT FROM AUTHOR]

Aims. We present a novel method for detecting outliers in astronomical time series based on the combination of a deep neural network and a k-nearest neighbor algorithm with the aim of identifying and removing problematic epochs in the light curves of astronomical objects. Methods. We used an EfficientNet network pretrained on ImageNet as a feature extractor and performed a k-nearest neighbor search in the resulting feature space to measure the distance from the first neighbor for each image. If the distance was above the one obtained for a stacked image, we flagged the image as a potential outlier. Results. We applied our method to a time series obtained from the VLT Survey Telescope monitoring campaign of the Deep Drilling Fields of the Vera C. Rubin Legacy Survey of Space and Time. We show that our method can effectively identify and remove artifacts from the VST time series and improve the quality and reliability of the data. This approach may prove very useful in light of the amount of data that will be provided by the LSST, which will prevent the inspection of individual light curves. We also discuss the advantages and limitations of our method and suggest possible directions for future work. [ABSTRACT FROM AUTHOR]

We investigated the prevalence of giant radio galaxies (GRGs), some of the largest structures powered by supermassive black holes, within supercluster environments, and the influence of such environments on their properties. Utilising two large catalogues of superclusters (401) and GRGs (1446), we established the existence of 77 GRGs (5.3%) residing in 64 superclusters (16%) within 0.05 ≤ z ≤ 0.42. Among the 77 GRGs found in superclusters, we identified ∼70% as residing within galaxy clusters. Within the subset of GRGs not located in superclusters, which constitutes 94.7% of the sample, a mere 21% are associated with galaxy clusters, while the remaining majority are situated in sparser environments. We examined the influence of differing environments, such as cluster versus non-cluster and supercluster versus non-supercluster regions, on the size of GRGs, while also exploring the driving factors behind their overall growth. Our findings show that the largest GRGs (≳3 Mpc) grow in underdense environments beyond the confines of dense environments. Moreover, we show that ∼24% of 1446 GRGs reside in galaxy clusters. We conclude that GRGs preferentially grow in sparser regions of the cosmic web and have a significantly larger median size. Finally, we demonstrate the potential of GRGs as astrophysical probes with specific cases where GRGs, exhibiting polarised emissions and located behind superclusters (acting as natural Faraday screens), were used to estimate magnetic field strengths of the supercluster environment at sub-microgauss levels. [ABSTRACT FROM AUTHOR]