Search

We present a study of high-cadence, high-precision optical light curves from the TESS satellite of 67 blazars in the southern sky. We provide descriptive flux statistics, power spectral density (PSD) model parameters, and characteristic variability timescales. We find that only 15 BL Lacertae objects (BLLs) and 18 flat spectrum radio quasars (FSRQs) from the initial 26 and 41, respectively, exhibit statistically significant variability. We employ an adapted power spectral response method to test the goodness of fit for the PSD function to three power-law variant models. From our best-fitting description of the PSD, we extract the high-frequency power-spectral slopes, and if present, determine the significant bend or break in the model to identify characteristic timescales. We find no significant difference in the excess variance or rms scatter between blazar subpopulations. We identify a linear rms–flux relation in ∼69% of our sample, in which ∼20% show a strong correlation. We find that both subpopulations of blazars show power spectral slopes of α ∼ 2 in which a broken power-law best fits five BLLs and six FSRQs and a bending power-law best fits one BLL and five FSRQs. The shortest timescales of variability in each light-curve range widely from minutes to weeks. Additionally, these objects' characteristic timescales range from ∼0.8 to 8 days, consistent with optical variability originating in the jet. [ABSTRACT FROM AUTHOR]

We present the High- z Evolution of Large and Luminous Objects (HELLO) project, a set of |$\sim \!30$| high-resolution cosmological simulations aimed to study Milky Way analogues (⁠|$M_\star \sim 10^{10-11}$|   |${\mathrm{M}}_{\odot }$|⁠) at high redshift (⁠|$z\sim [2-4]$|⁠). Based on the numerical investigation of a hundred astrophysical objects, HELLO features an updated scheme for chemical enrichment and the addition of local photoionization feedback. Independently of redshift and mass, our galaxies exhibit a smooth progression along the star formation main sequence until |$M_\star \sim \!10^{10.5}$|⁠ , around which our sample at |$z \sim 4$| remains mostly unperturbed while the most massive galaxies at |$z \sim 2$| reach their peak star formation rate (SFR) and its subsequent decline, due to a mix of gas consumption and stellar feedback. While active galactic nucleus feedback remains subdominant with respect to stellar feedback for energy deposition, its localized nature likely adds to the physical processes leading to declining SFRs. The phase in which a galaxy in our mass range can be found at a given redshift is set by its gas reservoir and assembly history. Finally, our galaxies are in excellent agreement with various scaling relations observed with the Hubble Space Telescope and the JWST , and hence can be used to provide the theoretical framework to interpret current and future observations from these facilities and shed light on the transition from star-forming to quiescent galaxies. [ABSTRACT FROM AUTHOR]

We investigate the thermodynamics of close encounters between stellar mass black holes (BHs) in the gaseous discs of active galactic nuclei (AGNs), during which binary black holes (BBHs) may form. We consider a suite of 2D viscous hydrodynamical simulations within a shearing box prescription using the Eulerian grid code athena ++. We study formation scenarios where the fluid is either an isothermal gas or an adiabatic mixture of gas and radiation in local thermal equilibrium. We include the effects of viscous and shock heating, as well as optically thick cooling. We co-evolve the embedded BHs with the gas, keeping track of the energetic dissipation and torquing of the BBH by gas and inertial forces. We find that compared to the isothermal case, the minidiscs formed around each BH are significantly hotter and more diffuse, though BBH formation is still efficient. We observe massive blast waves arising from collisions between the radiative minidiscs during both the initial close encounter and subsequent periapsis periods for successfully bound BBHs. These 'disc novae' have a profound effect, depleting the BBH Hill sphere of gas and injecting energy into the surrounding medium. In analysing the thermal emission from these events, we observe periodic peaks in local luminosity associated with close encounters/periapses, with emission peaking in the optical/near-infrared (IR). In the AGN outskirts, these outbursts can reach 4 per cent of the AGN luminosity in the IR band, with flares rising over 0.5–1 yr. Collisions in different disc regions, or when treated in 3D with magnetism, may produce more prominent flares. [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]

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 spectroscopically confirm the M UV = −20.5 mag galaxy GHZ2/GLASS-z12 to be at redshift z = 12.34. The source was selected via NIRCam photometry in GLASS-JWST Early Release Science data, providing the first evidence of a surprising abundance of bright galaxies at z ≳ 10. The NIRSpec PRISM spectrum shows detections of N iv, C iv, He ii, O iii, C iii, O ii, and Ne iii lines and the first detection at high redshift of the O iii Bowen fluorescence line at 3133 Å rest frame. The prominent C iv line with rest-frame equivalent width (EW) ≈ 46 Å puts GHZ2 in the category of extreme C iv emitters. GHZ2 displays UV lines with EWs that are only found in active galactic nuclei (AGNs) or composite objects at low/intermediate redshifts. The UV line-intensity ratios are compatible with both AGNs and star formation in a low-metallicity environment, with the low limit on the [Ne iv ]/[N iv ] ratio favoring a stellar origin of the ionizing photons. We discuss a possible scenario in which the high ionizing output is due to low-metallicity stars forming in a dense environment. We estimate a metallicity ≲0.1 Z / Z ⊙, a high ionization parameter log U > −2, a N/O abundance 4–5 times the solar value, and a subsolar C/O ratio similar to the recently discovered class of nitrogen-enhanced objects. Considering its abundance patterns and the high stellar mass density (104 M ⊙ pc−2), GHZ2 is an ideal formation site for the progenitors of today's globular clusters. The remarkable brightness of GHZ2 makes it a "Rosetta stone" for understanding the physics of galaxy formation within just 360 Myr after the Big Bang. [ABSTRACT FROM AUTHOR]

Models of the resolved Event Horizon Telescope (EHT) sources Sgr A* and M87* are constrained by observations at multiple wavelengths, resolutions, polarizations, and time cadences. In this paper, we compare unresolved circular polarization (CP) measurements to a library of models, where each model is characterized by a distribution of CP over time. In the library, we vary the spin of the black hole, the magnetic field strength at the horizon (i.e., both SANE and magnetically arrested disk or MAD models), the observer inclination, a parameter for the maximum ion–electron temperature ratio assuming a thermal plasma, and the direction of the magnetic field dipole moment. We find that Atacama Large Millimeter/submillimeter Array (ALMA) observations of Sgr A* are inconsistent with all edge-on (i = 90°) models. Restricting attention to the MAD models favored by earlier EHT studies of Sgr A*, we find that only models with magnetic dipole moment pointing away from the observer are consistent with ALMA data. We also note that in 26 of the 27 passing MAD models, the accretion flow rotates clockwise on the sky. We provide a table of the means and standard deviations of the CP distributions for all model parameters, along with their trends. [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]

Measuring the environments of massive galaxies at high redshift is crucial to understanding galaxy evolution and the conditions that gave rise to the distribution of matter we see in the Universe today. While high- z radio galaxies (H z RGs) and quasars tend to reside in protocluster-like systems, the environments of their radio-quiet counterparts are relatively unexplored, particularly in the submillimetre, which traces dust-obscured star formation. In this study, we search for 850  μ m-selected submillimetre galaxies (SMGs) in the environments of massive (⁠|$M_{\star }$| |$\gt 10^{11}$| |${\rm M}_{\odot }$|⁠), radio-quiet (⁠|$L_{500 {\rm MHz}}$| |$\lesssim 10^{25}$|  WHz |$^{-1}$|⁠) galaxies at |$z \sim 1\!-\!3$| using data from the SCUBA-2 COSMOS (S2COSMOS) survey. By constructing number counts in circular regions of radius 1–6 arcmin and comparing with blank-field measurements, we find no significant overdensities of SMGs around massive radio-quiet galaxies at any of these scales, despite being sensitive down to overdensities of |$\delta \sim 0.4$|⁠. To probe deeper than the catalogue we also examine the distribution of peaks in the SCUBA-2 signal-to-noise (SNR) map, which reveals only tentative signs of any difference in the SMG densities of the radio-quiet galaxy environments compared to the blank field, and only on smaller scales (1 arcmin radii, corresponding to |$\sim 0.5$|  Mpc) and higher SNR thresholds. We conclude that massive, radio-quiet galaxies at cosmic noon are typically in environments with |$\delta \lesssim 0.4$|⁠ , which are either consistent with the blank field or contain only weak overdensities spanning sub-Mpc scales. The contrast between our results and studies of H z RGs with similar stellar masses and redshifts implies an intrinsic link between the wide-field environment and the radio luminosity of the active galactic nucleus at high redshift. [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]

The intergalactic medium in the vicinity of galaxy protoclusters are interesting testbeds to study complex baryonic effects such as gravitational shocks and feedback. Here, we utilize hydrodynamical simulations from the SIMBA and The Three Hundred suites to study the mechanisms influencing large-scale Lyman- |$\alpha$| transmission in |$2\lt z\lt 2.5$| protoclusters. We focus on the matter overdensity-Lyman- |$\alpha$| transmission relation |$(\delta _m-\delta _F)$| on Megaparsec-scales in these protoclusters, which is hypothesized to be sensitive to the feedback implementations. The lower density regions represented by the SIMBA-100 cosmological volume trace the power-law |$\delta _m-\delta _F$| relationship often known as the fluctuating Gunn–Peterson approximation. This trend is continued into higher density regions covered by simulations that implement stellar feedback only. Simulations with active galactic nucleus (AGN) thermal and AGN jet feedback, however, exhibit progressively more Lyman- |$\alpha$| transmission at fixed matter overdensity. Compared with the seven protoclusters observed in the COSMOS field, only two display the excess absorption expected from protoclusters. The others exhibit deviations: four show some increased transparency suggested by AGN X-ray thermal feedback models while the highly transparent COSTCO-I protocluster appears to reflect intense jet feedback. Discrepancies with the stellar-feedback-only model suggests processes at play beyond gravitational heating and/or stellar feedback as the cause of the protocluster transparencies. Some form of AGN feedback is likely at play in the observed protoclusters, and possibly long-ranged AGN jets in the case of COSTCO-I. While more detailed and resolved simulations are required to move forward, our findings open new avenues for probing AGN feedback at Cosmic Noon. [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 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]

Atomic hydrogen (H  i) serves a crucial role in connecting galactic-scale properties such as star formation with the large-scale structure of the Universe. While recent numerical simulations have successfully matched the observed covering fraction of H  i near Lyman Break Galaxies (LBGs) and in the foreground of luminous quasars at redshifts |$z \lesssim 3$|⁠ , the low-mass end remains as-of-yet unexplored in observational and computational surveys. We employ a cosmological, hydrodynamical simulation (FIREbox) supplemented with zoom-in simulations (MassiveFIRE) from the Feedback In Realistic Environments (FIRE) project to investigate the H  i covering fraction of Lyman Limit Systems (⁠|$N_{{\text{H}}\, \rm{{\small I}}} \gtrsim 10^{17.2}$|  cm |$^{-2}$|⁠) across a wide range of redshifts (⁠|$z=0-6$|⁠) and halo masses (⁠|$10^8-10^{13} \, \,\mathrm{ M}_{\odot }$| at |$z=0$|⁠ , |$10^8-10^{11}\, \,\mathrm{ M}_{\odot }$| at |$z=6$|⁠) in the absence of feedback from active galactic nuclei. We find that the covering fraction inside haloes exhibits a strong increase with redshift, with only a weak dependence on halo mass for higher mass haloes. For massive haloes (⁠|$M_{\mathrm{vir}} \sim 10^{11}-10^{12} \,\mathrm{ M}_{\odot }$|⁠), the radial profiles showcase scale-invariance and remain independent of mass. The radial dependence is well captured by a fitting function. The covering fractions in our simulations are in good agreement with measurements of the covering fraction in LBGs. Our comprehensive analysis unveils a complex dependence with redshift and halo mass for haloes with |$M_{\mathrm{vir}} \lesssim 10^{10} \,\mathrm{ M}_{\odot }$| that future observations aim to constrain, providing key insights into the physics of structure formation and gas assembly. [ABSTRACT FROM AUTHOR]

The relation between nuclear star clusters (NSCs) and the growth of the central supermassive black holes (SMBHs), as well as their connection to the properties of the host galaxies, is crucial for understanding the evolution of galaxies. Recent observations have revealed that about 10 per cent of nucleated galaxies host hybrid nuclei, consisting of both NSCs and accreting SMBHs that power active galactic nuclei (AGNs). Motivated by the potential of the recently published multiwavelength data sets from LeMMINGs survey, here we present the most thorough investigation to date of the incidence of hybrid nuclei in a large sample of 100 nearby nucleated galaxies (10 E, 25 S0, 63 S, and 2 Irr), covering a wide range in stellar mass (⁠|$M_{*,\rm gal} \sim 10^{8.7}-10^{12}~\rm M_{\odot }$|⁠). We identify the nuclei and derive their properties by performing detailed 1D and 2D multicomponent decompositions of the optical and near-infrared HST stellar light distributions of the galaxies using Sérsic and core-Sérsic models. Our AGN diagnostics are based on homogeneously derived nuclear 1.5 GHz e -MERLIN radio, Chandra X-ray (0.3–10 keV), and optical emission-line data. We determine the nucleation fraction (⁠|$f_{\rm nuc}$|⁠) as the relative incidence of nuclei across the LeMMINGs HST sample and find |$f_{\rm nuc} =~$| 100/149 (= 67 |$\pm$| 7 per cent), confirming previous work, with a peak value of |$49/56~(= 88 \pm 13$|  per cent) at bulge masses |$M_{*,\rm bulge}\sim 10^{9.4}- 10^{10.8}~ \rm M_{\odot }$|⁠. We identify 30 nucleated LeMMINGs galaxies that are optically active, radio-detected, and X-ray luminous (⁠|$L_\textnormal {X} \gt 10^{39}$| erg s |$^{-1}$|⁠). This indicates that our nucleated sample has a lower limit |$\sim$| 30 per cent occupancy of hybrid nuclei, which is a function of |$M_{*,\rm bulge}$| and |$M_{*,\rm gal}$|⁠. We find that hybrid nuclei have a number density of |$(1.5 \pm 0.4)\times 10^{-5}$|  Mpc |$^{-3}$|⁠ , are more common at |$M_{*,\rm gal}\sim 10^{10.6}- 10^{11.8}~\rm M_{\odot }$| and occur, at least, three times more frequently than previously reported. [ABSTRACT FROM AUTHOR]

We develop a model for galaxy formation and the growth of supermassive black holes (SMBHs), based on the fact that cold dark matter haloes form their gravitational potential wells through a fast phase with rapid change in the potential, and that the high universal baryon fraction makes cooled gas in haloes self-gravitating and turbulent before it can form rotation-supported discs. Gas fragmentation produces subclouds so dense that cloud–cloud collision and drag on clouds are not significant, producing a dynamically hot system of subclouds that form stars and move ballistically to feed the central SMBH. Active galactic nucleus (AGN) and supernova feedback is effective only in the fast phase, and the cumulative effects are to regulate star formation and SMBH growth, as well as to reduce the amount of cold gas in haloes to allow the formation of globally stable discs. Using a set of halo assembly histories, we demonstrate that the model can reproduce a number of observations, including correlations among SMBH mass, stellar mass of galaxies and halo mass, the number densities of galaxies and SMBH, as well as their evolution over the cosmic time. [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]

We present the discovery of large radio shells around a massive pair of interacting galaxies and extended diffuse X-ray emission within the shells. The radio data were obtained with the Australian Square Kilometre Array Pathfinder (ASKAP) in two frequency bands centred at 944 MHz and 1.4 GHz, respectively, while the X-ray data are from the XMM–Newton observatory. The host galaxy pair, which consists of the early-type galaxies ESO 184-G042 and LEDA 418116, is part of a loose group at a distance of only 75 Mpc (redshift |$z = 0.017$|⁠). The observed outer radio shells (diameter |${\sim}$| 145 kpc) and ridge-like central emission of the system, ASKAP J1914−5433 (Physalis), are likely associated with merger shocks during the formation of the central galaxy (ESO 184-G042) and resemble the new class of odd radio circles (ORCs). This is supported by the brightest X-ray emission found offset from the centre of the Physalis system, instead centred at the less massive galaxy, LEDA 418116. The host galaxy pair is embedded in an irregular envelope of diffuse light, highlighting ongoing interactions. We complement our combined radio and X-ray study with high-resolution simulations of the circumgalactic medium (CGM) around galaxy mergers from the Magneticum project to analyse the evolutionary state of the Physalis system. We argue that ORCs/radio shells could be produced by a combination of energy release from the central active galactic nucleus and subsequent lightening up in radio emission by merger shocks travelling through the CGM of these systems. [ABSTRACT FROM AUTHOR]

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

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

In recent years, cosmological hydrodynamical simulations have proven their utility as key interpretative tools in the study of galaxy formation and evolution. In this work, we present a comparative analysis of the baryon cycle in three publicly available, leading cosmological simulation suites: EAGLE, IllustrisTNG, and SIMBA. While these simulations broadly agree in terms of their predictions for the stellar mass content and star formation rates of galaxies at |$z\approx 0$|⁠ , they achieve this result for markedly different reasons. In EAGLE and SIMBA, we demonstrate that at low halo masses (⁠|$M_{\rm 200c}\lesssim 10^{11.5}\, \mathrm{M}_{\odot }$|⁠), stellar feedback (SF)-driven outflows can reach far beyond the scale of the halo, extending up to |$2\!-\!3\times R_{\rm 200c}$|⁠. In contrast, in TNG, SF-driven outflows, while stronger at the scale of the interstellar medium, recycle within the circumgalactic medium (within |$R_{\rm 200c}$|⁠). We find that active galactic nucleus (AGN)-driven outflows in SIMBA are notably potent, reaching several times |$R_{\rm 200c}$| even at halo masses up to |$M_{\rm 200c}\approx 10^{13.5}\, \mathrm{M}_{\odot }$|⁠. In both TNG and EAGLE, AGN feedback can eject gas beyond |$R_{\rm 200c}$| at this mass scale, but seldom beyond |$2\!-\!3\times R_{\rm 200c}$|⁠. We find that the scale of feedback-driven outflows can be directly linked with the prevention of cosmological inflow, as well as the total baryon fraction of haloes within |$R_{\rm 200c}$|⁠. This work lays the foundation to develop targeted observational tests that can discriminate between feedback scenarios, and inform subgrid feedback models in the next generation of simulations. [ABSTRACT FROM AUTHOR]

Red Geysers are galaxies with low-star formation rates and galactic scale ionized outflows likely driven by low-luminosity active galactic nuclei (AGN). We investigated the impact of AGN winds on the oxygen abundance using integral field spectroscopic data from Mapping Nearby Galaxies for Red Geysers, control galaxies (quiescent galaxies without outflows), and AGN hosts within the inner 1.5 kpc radius. Red Geyser galaxies have higher W |$_{80}$| values compared to those of AGN and controls, with 64 per cent showing W |$_{80}\gt 500$|  km s |$^{-1}$| that is indicative of outflow. Only 40 per cent of controls and 31 per cent of AGNs reach this value. We found a small tendency of the oxygen abundance distribution of controls to be biased towards higher values than those of Red Geysers. However, Red Geysers do not show a correlation between H |$\alpha$| width (parametrized by the W |$_{\rm 80}$|⁠) and oxygen abundance, which indicates that AGN winds are not significantly impacting the chemical abundance of the nuclear region of these galaxies. The oxygen abundance distribution mean value for the tree samples is |$\rm 12+log(O/H)\sim$| 8.7 (⁠|$\mathit{Z}\sim \rm Z_{\odot })$|⁠. On the other hand, AGN hosts show a positive correlation between W |$_{80}$| and O/H which could be due to star formation that outflows from the active nuclei could induce; or to the reservoir of gas that makes the nucleus active, and its is also used in the star formation. [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]

The complexity of the energy levels in Fe ii has made it difficult to theoretically interpret its observational emission spectrum. However, addressing this challenge could provide valuable insights into the main sequence of QSOs using "eigenvector 1" and the chemical evolution of the Universe. Although the templates based on I Zw 1 are widely used, their universality remains unexplained. To address this, we utilized the CLOUDY spectral synthesis code to generate theoretical blends of Fe ii optical emission near the H β region. Our results indicate that the optimal cloud density and photon flux align with previous studies at gas density 1011 cm−3 and photon flux 1020.5 cm−2 s−1. We discovered a broad parameter region that fits the data well, encompassing a diverse range of densities and photon fluxes. This helps to explain the general applicability of optical templates. Additionally, we investigated the effects of different spectral energy distributions (SEDs), Eddington ratios, turbulence, and cloud column densities and found that they provided a sufficiently broad range for typical emitting clouds. We found different SEDs had a negligible impact on the template shape, further expanding the usability of empirical templates. However, they significantly affected the absolute intensity of Fe ii emission, consistent with previous research. Furthermore, we determined that a turbulence of approximately 100 km s−1 is necessary to produce sufficiently strong optical Fe ii, and either a column density greater than 1024 cm−2, which is typical for Fe ii UV emission, or an abundance higher than solar is preferred. [ABSTRACT FROM AUTHOR]

We have characterized the ionized, neutral, and warm molecular gas kinematics in the Seyfert 1 galaxy NGC 3227 using observations from the Hubble Space Telescope Space Telescope Imaging Spectrograph, Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph, Gemini-North's Near-Infrared Integral Field Spectrometer, and the Atacama Large Millimeter/submillimeter Array. We fit multiple Gaussians to several spatially resolved emission lines observed with long-slit and integral-field spectroscopy and isolate the kinematics based on apparent rotational and outflowing motions. We use the kinematics to determine an orientation for the bicone along which the outflows travel and find that the biconical structure has an inclination of 40 − 4 + 5 ° from our line of sight and a half-opening angle with an inner and outer boundary of 47 − 2 + 6 ° and 68 − 1 + 1 °, respectively. We observe ionized outflows traveling 500 km s−1 at distances up to 7″ (800 pc) from the supermassive black hole (SMBH) and disturbed ionized gas up to a distance of 15″ (1.7 kpc). Our analysis reveals that the ionized outflows are launched from within 20 pc of the SMBH, at the same location as a bridge of cold gas across the nucleus detected in Atacama Large Millimeter/submillimeter Array CO(2–1) observations. We measure a turnover radius where the gas starts decelerating at a distance of 26 ± 6 pc from the active galactic nucleus. Compared to a turnover radius in the range of 31−63 pc from a radiative driving model, we confirm that radiative driving is the dominant acceleration mechanism for the narrow-line region outflows in NGC 3227. [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]

Previous X-ray works on Mrk 1239 have revealed a complex narrow-line Seyfert 1 that exhibits substantial absorption and strong emission from both collisionally ionized and photoionized plasmas. Here, we report on deep-pointed observations with XMM-Newton and NuSTAR, along with Swift monitoring, to understand the 0.3–30 keV continuum emission and the central engine geometry. A strong X-ray flare, where the AGN brightens by a factor of 5 in ∼30 ks, is captured between 4 and 30 keV and can be attributed to a brightening of the primary continuum. However, the lack of any variability below ∼3 keV on long or short timescales requires complete absorption of the AGN continuum with a neutral medium of column density ∼1023.5 cm−2. The timing and spectral properties are consistent with a blurred reflection interpretation for the primary emission. The variability and presence of a Compton hump disfavors ionized partial covering. The neutral absorber, if outflowing, could be crashing into the surrounding medium and interstellar medium to produce the low-energy continuum and collisionally ionized emission. Scattered emission off the inner torus could produce the photoionized emission. The intricate scenario is demanded by the data and highlights the complexity of the environment that is normally invisible when overwhelmed by the AGN continuum. Objects like Mrk 1239 serve as important sources for unveiling the interface between the AGN and host galaxy environments. [ABSTRACT FROM AUTHOR]

We present the first detailed radio study of the galaxy cluster XMMXCS J2215.9−1738 at z  = 1.46 using MeerKAT L -band (1.3 GHz) observations. We combine our radio observation with archival optical and infrared data to investigate the star formation and active galactic nucleus (AGN) population within |$R_{200}$| (⁠|$R =$| 0.8 Mpc) of the cluster centre. Using three selection criteria; the radio luminosity, the far-infrared radio ratio (⁠|$q_{\rm {IR}}$|⁠), and the mid-infrared colour, we distinguish galaxies with radio emission predominantly powered by star formation from that powered by AGNs. We selected 24 cluster members within |$R_{\rm {200}}$| in the MeerKAT image based on either their photometric or spectroscopic redshift. We classified 12/24 (50 per cent) as galaxies whose radio emission is dominated by star-formation activity, 6/24 (25 per cent) as intermediate star-forming galaxies, and 6/24 (25 per cent) as AGN-dominated galaxies. Using the radio continuum luminosities of the star-forming cluster galaxies, we estimated an integrated star formation rate (SFR) value of 1700 |$\pm$| 330 M |$_{\odot }$|  yr |$^{-1}$| within |$R_{200}$|⁠. We derived a mass-normalized integrated SFR value of |$(570 \pm 110) \times 10^{-14}$|  yr |$^{-1}$|⁠. This supports previous observational and theoretical studies that indicated a rapid increase in star formation activity within the core of high-redshift clusters. We also show that the high-AGN fraction within the cluster core is consistent with previous cluster observations at |$z \gt $| 1.5. [ABSTRACT FROM AUTHOR]

In the absence of supplementary heat, the radiative cooling of halo gas around massive galaxies (Milky Way mass and above) leads to an excess of cold gas or stars beyond observed levels. Active galactic nucleus jet-induced heating is likely essential, but the specific properties of the jets remain unclear. Our previous work concludes from simulations of a halo with |$10^{14} \,\mathrm{ M}_\odot$| that a successful jet model should have an energy flux comparable to the free-fall energy flux at the cooling radius and should inflate a sufficiently wide cocoon with a long enough cooling time. In this paper, we investigate three jet modes with constant fluxes satisfying the criteria, including high-temperature thermal jets, cosmic ray (CR)-dominant jets, and widely precessing kinetic jets in |$10^{12}-10^{15}\, {\rm M}_{\odot }$| haloes using high-resolution, non-cosmological magnetohydrodynamic simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, conduction, and viscosity. We find that scaling the jet energy according to the free-fall energy at the cooling radius can successfully suppress the cooling flows and quench galaxies without violating observational constraints. On the contrary, if we scale the energy flux based on the total cooling rate within the cooling radius, strong interstellar medium cooling dominates this scaling, resulting in a jet flux exceeding what is needed. Among the three jet types, the CR-dominant jet is most effective in suppressing cooling flows across all surveyed halo masses due to enhanced CR pressure support. We confirm that the criteria for a successful jet model work across a wider range, encompassing halo masses of |$10^{12}-10^{15} {\rm M_\odot }$|⁠. [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]

This document is a correction to a paper titled "Determining star-formation rates in active galactic nuclei hosts via stellar population synthesis." The correction addresses an inconsistency in the value of |$H_0$| used in the analysis. The authors have now adopted a uniform value of |$H_0=73.0$| km s|$^{-1}$| Mpc|$^{-1}$| for both star-formation rates (SFR|$_\\star$| and SFR|$_{Gas}$|). As a result, some figures and the transformation equation have been updated. The conclusions of the paper remain unchanged. The document provides the corrected equations and figures for reference. [Extracted from the article]

We present the analysis of publicly available NuSTAR, Suzaku , and XMM–Newton observations of the symbiotic recurrent nova T CrB covering the 2006.77–2022.66 yr period. The X-ray spectra are analysed by adopting a model that includes a reflection component produced by the presence of a disc that mimics the accretion disc and the immediate surrounding medium. Our best-fitting model requires this disc to have a radius of 1 au, effective thickness of 0.1 au, averaged column density 10 |$^{25}$|  cm |$^{-2}$| and orientation of 50 |$^{\circ }$| with respect to the line of sight. This disc is about a factor of two larger than recent estimations for the accretion disc and its presence contributes significantly via reflection to the total X-ray flux detected from T CrB, which naturally produces the emission of the 6.4 keV Fe line. Our analysis suggests that the temperature of the boundary layer evolved from 14.8 keV in the steady-state phase (before 2016), to 2.8 keV in the 2017.24 epoch, to finally stabilize to about |$\sim$| 8 keV in the subsequent epochs. These variations in the plasma temperature of the boundary layer are attributed to the evolution of the mass accretion rate (⁠|$\dot{M}_\mathrm{acc}$|⁠), which is estimated to have an averaged value of |$\dot{M}_\mathrm{acc}$|  = 2.6 |$\times \,10^{-8}$|  M |$_\odot$|  yr |$^{-1}$| for the current active phase. The presence of emission lines in the XMM–Newton Reflection Grating Spectrometer spectrum of 2017.24 prevents from adopting a blackbody emission model to fit the soft X-ray range. Instead, we use plasma emission models that suggest the presence of adiabatically shocked gas produced by gas velocities of 110–200 km s |$^{-1}$|⁠ , very likely tracing jet-like ejections similar to what is found in other symbiotic systems. The analysis of X-ray and optical data together show that T CrB has a similar evolution as black hole binaries, accreting neutron stars and active galactic nuclei in the hardness–intensity diagram. [ABSTRACT FROM AUTHOR]

Radio bubbles, ubiquitous features of the intracluster medium around active galactic nuclei, are known to rise buoyantly for multiple scale heights through the intracluster medium (ICM). It is an open question how the bubbles can retain their high-energy cosmic-ray content over such distances. We propose that the enhanced scattering of cosmic rays due to micromirrors generated in the ICM is a viable mechanism for confining the cosmic rays within bubbles and can qualitatively reproduce their morphology. We discuss the observational implications of such a model of cosmic-ray confinement. [ABSTRACT FROM AUTHOR]

In this work, we present the results of a detailed X-ray spectral analysis of the brightest active galactic nuclei (AGNs) detected in the XMM–Newton 1.75 Ms Ultra Narrow Deep Field. We analysed 23 AGNs that have a luminosity range of |$\sim 10^{42} {\!-\!} 10^{46}\, \rm {erg}\, \rm {s}^{-1}$| in the |$2 {\!-\!} 10\, \rm {keV}$| energy band, redshifts up to 2.66, and |$\sim 10\,000$| X-ray photon counts in the |$0.3{ \!-\! }10\, \rm {keV}$| energy band. Our analysis confirms the 'Iwasawa – Taniguchi effect,' an anticorrelation between the X-ray luminosity (⁠|$L_x$|⁠) and the Fe – k |$\alpha$| equivalent width (⁠|${\rm EW}_{\rm Fe}$|⁠) possibly associated with the decreasing of the torus covering factor as the AGN luminosity increases. We investigated the relationship among black hole mass (⁠|$M_{\rm BH}$|⁠), |$L_x$|⁠ , and X-ray variability, quantified by the Normalized Excess Variance (⁠|$\sigma ^2_{\rm rms}$|⁠). Our analysis suggest an anticorrelation in both |$M_{\rm BH} - \sigma ^2_{\rm rms}$| and |$L_x- \sigma ^2_{\rm rms}$| relations. The first is described as |$\sigma ^2_{\rm rms} \propto M^{-0.26 \pm 0.05}_{\rm BH}$|⁠ , while the second presents a similar trend with |$\sigma ^2_{\rm rms} \propto L_{x}^{-0.31 \pm 0.04}$|⁠. These results support the idea that the luminosity – variability anticorrelation is a byproduct of an intrinsic relationship between the BH mass and the X-ray variability, through the size of the emitting region. Finally, we found a strong correlation among the Eddington ratio (⁠|$\lambda _{\rm Edd}$|⁠), the hard X-ray photon index (⁠|$\Gamma$|⁠), and the illumination factor |$\log (A)$|⁠ , which is related to the ratio between the number of Compton scattered photons and the number of seed photons. The |$\log (\lambda _{\rm Edd})-\Gamma -\log (A)$| plane could arise naturally from the connection between the accretion flow and the hot corona. [ABSTRACT FROM AUTHOR]

This paper investigates the accretion of neutron stars (NSs) in active galactic nucleus (AGN) accretion discs. We classify potential accretion modes of NSs in AGN discs, proposing a hierarchical model of NS accretion: accretion flow from the Bondi sphere to accretion columns. The accretion of NSs in AGN discs differs from that of BHs, especially within the scale of the NS's magnetosphere due to its hard surface and magnetic field. As the accretion flow approaches the magnetosphere, the magnetic fields guide the accretion flow to form accretion columns, primarily dominated by neutrinos. While neutrinos generated from single NS accretion may not have observable effects, considering the all-sky background, they contribute to the neutrino background in the sub-MeV energy range comparable to that of supernova explosions. NS accretion may also lead to the generation of mass quadrupole moments, consequently generating gravitational waves (GWs). The GWs, which exhibit characteristic effects like periodic modulations and echoes, could be observed by third-generation GW detectors. The emission of neutrinos and GWs carries away energy and angular momentum brought by accretion, reducing the feedback effect on the AGN disc. This results in an exceptionally high NS accretion rate, leading to a collapse time-scale shorter than the migration-merge time-scale, making it less likely that binary NS mergers originate from AGN discs. [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]

The fundamental plane of black hole activity is a very important tool to study accretion and jets. However, we found that the SEDs of AGNs and XRBs are different in the 2–10 keV energy band, and it seems inappropriate to use 2–10 keV X-ray luminosities to study the fundamental plane. In this work, we use the luminosity near the peak of the blackbody radiation of the active galactic nuclei and black hole binaries to replace the 2–10 keV luminosity. We re-explore the fundamental plane of black hole activity by using the 2500 A ˚ luminosity as the peak luminosity of the blackbody radiation of AGNs and 1 keV luminosity as the peak luminosity of the blackbody radiation of XRBs. We compile samples of black hole binaries and active galactic nuclei with luminosity near the peak luminosity of blackbody radiation and study the fundamental plane between radio luminosity ( L R ), the peak luminosity of blackbody radiation ( L peak ), and black hole mass ( M BH ). We find that the radio–peak luminosity correlations are L 5 GHz / L Edd ∝ (L 2500 A ˚ / L Edd) 1.55 and L 5 GHz / L Edd ∝ (L 1 keV / L Edd) 1.53 for AGN and XRB, respectively, in the radiatively efficient sample, and L 5 GHz / L Edd ∝ (L 2500 A ˚ / L Edd) 0.48 and L 5 GHz / L Edd ∝ (L 1 keV / L Edd) 0.53 in the radiatively inefficient sample, respectively. Based on the similarities in radio–peak correlations, we further propose a fundamental plane in radio luminosity, the peak luminosity of blackbody radiation, and black hole mass, which is radiatively efficient: log L 5 GHz = 1. 57 − 0.01 + 0.01 log L peak − 0. 32 − 0.16 + 0.16 log M BH − 27. 73 − 0.34 + 0.34 with a scatter of σ R = 0.48 dex, and radiatively inefficient: log L 5 GHz = 0. 45 − 0.01 + 0.01 log L peak + 0. 91 − 0.10 + 0.12 log M BH + 12. 58 − 0.38 + 0.38 with a scatter of σ R = 0.63 dex. Our results are similar to those of previous studies on the fundamental plane for radiatively efficient and radiatively inefficient black hole activity. However, our results exhibit a smaller scatter, so when using the same part of blackbody radiation (i.e., the peak luminosity of the blackbody radiation), the fundamental plane becomes a little bit tighter. [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]

Binary black holes (BBHs) embedded within the accretion disks that fuel active galactic nuclei (AGN) are promising progenitors for the source of gravitational wave (GW) events detected by LIGO/VIRGO. Several recent studies have shown that when these binaries form, they are likely to be highly eccentric and retrograde. However, many uncertainties remain concerning the orbital evolution of these binaries as they either inspiral toward merger or disassociate. Previous hydrodynamical simulations exploring their orbital evolution have been predominantly two-dimensional or have been restricted to binaries on nearly circular orbits. We present the first high-resolution, three-dimensional local shearing-box simulations of both prograde and retrograde eccentric BBHs embedded in AGN disks. We find that retrograde binaries shrink several times faster than their prograde counterparts and exhibit significant orbital eccentricity growth, the rate of which monotonically increases with binary eccentricity. Our results suggest that retrograde binaries may experience runaway orbital eccentricity growth, which may bring them close enough together at pericenter for GW emission to drive them to coalescence. Although their eccentricity is damped, prograde binaries shrink much faster than their orbital eccentricity decays, suggesting they should remain modestly eccentric as they contract toward merger. Finally, binary precession driven by the AGN disk may dominate over precession induced by the supermassive black hole depending on the binary accretion rate and its location in the AGN disk, which can subdue the evection resonance and von Ziepel–Lidov–Kozai cycles. [ABSTRACT FROM AUTHOR]

X-ray polarization, which now can be measured by the Imaging X-ray Polarimetry Explorer (IXPE), is a new probe of jets in the supermassive black hole systems of active galactic nuclei (AGNs). Here, we summarize IXPE observations of radio-loud AGNs that have been published thus far. Blazars with synchrotron spectral energy distributions (SEDs) that peak at X-ray energies are routinely detected. The degree of X-ray polarization is considerably higher than at longer wavelengths. This is readily explained by energy stratification of the emission regions when electrons lose energy via radiation as they propagate away from the sites of particle acceleration as predicted in shock models. However, the 2–8 keV polarization electric vector is not always aligned with the jet direction as one would expect unless the shock is oblique. Magnetic reconnection may provide an alternative explanation. The rotation of the polarization vector in Mrk421 suggests the presence of a helical magnetic field in the jet. In blazars with lower-frequency peaks and the radio galaxy Centaurus A, the non-detection of X-ray polarization by IXPE constrains the X-ray emission mechanism. [ABSTRACT FROM AUTHOR]

Active galactic nuclei (AGNs), either radio-quiet or radio-loud, had never been observed in X-ray polarized light until the advent of the Imaging X-ray Polarimetry Explorer (IXPE) in the end of 2021. This satellite opened a new observational window for studying supermassive black holes and their complex environment. In this regard, radio-quiet AGNs are probably better targets than radio-loud objects to probe accretion processes due to the lack of synchrotron emission from jets that can dilute the polarized signal from the central engine. Their relatively clean environment not only allows to detect and measure the X-ray polarization originating from the hot corona responsible for X-ray emission, but also to assess the geometry of the media immediately surrounding the supermassive black hole. Such geometrical measurements work just as well for characterizing the corona morphology in pole-on AGNs as it does for determining the three-dimensional shape of the circumnuclear cold obscurer (the so-called torus) in edge-on AGNs. In this review paper, we will return to each of the observations made by IXPE so far in the field of radio-quiet AGNs and highlight the fundamental contribution of X-ray polarimetry to our understanding of how light is emitted and how matter is shaped around supermassive black holes. [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]

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

Understanding the links between different phases of outflows from active galactic nuclei is a key goal in extragalactic astrophysics. Here, we compare [O  iii ]  |$\lambda \lambda$| 4960, 5008 outflow signatures in quasars with and without broad absorption lines (BALs), aiming to test how the broad absorption troughs seen in the rest-frame ultraviolet are linked to the narrow line region outflows seen in the rest-frame optical. We present new near-infrared spectra from Magellan/FIRE that cover [O  iii ] in 12 quasars with |$2.1\lt z\lt 2.3$|⁠ , selected to have strong outflow signatures in C  iv |$\lambda$| 1550. Combining with data from the literature, we build a sample of 73 BAL, 115 miniBAL, and 125 non-BAL quasars with |$1.5\lt z\lt 2.6$|⁠. The strength and velocity width of [O  iii ] correlate strongly with the C  iv emission properties, but no significant difference is seen in the [O  iii ] emission-line properties between the BALs, non-BALs, and miniBALs once the dependence on C  iv emission is taken into account. A weak correlation is observed between the velocities of C  iv BALs and [O  iii ] emission, which is accounted for by the fact that both outflow signatures correlate with the underlying C  iv emission properties. Our results add to the growing evidence that BALs and non-BALs are drawn from the same parent population and are consistent with a scenario wherein BAL troughs are intermittent tracers of persistent quasar outflows, with a part of such outflow becoming optically thick along our line of sight for sporadic periods of time within which BALs are observed. [ABSTRACT FROM AUTHOR]

Given their dominance of the galaxy number density, dwarf galaxies are central to our understanding of galaxy formation. While the incidence of active galactic nuclei (AGN) and their impact on galaxy evolution have been extensively studied in massive galaxies, much less is known about the role of AGN in the evolution of dwarfs. We search for radiatively efficient AGN in the nearby (0.1 < z < 0.3) dwarf (108 M⊙ < M ⋆ < 1010 M⊙) population, using spectral energy distribution fitting (via prospector) applied to deep ultraviolet to mid-infrared photometry of 508 dwarf galaxies. Around a third (32 ± 2 per cent) of our dwarfs show signs of AGN activity. We compare the properties of our dwarf AGN to control samples, constructed from non-AGN, which have the same distributions of redshift and stellar mass as their AGN counterparts. Kolmogorov–Smirnov tests between the AGN and control distributions indicate that the AGN do not show differences in their distances to nodes, filaments, and nearby massive galaxies from their control counterparts. This indicates that AGN triggering in the dwarf regime is not strongly correlated with local environment. The fraction of AGN hosts with early-type morphology and those that are interacting are also indistinguishable from the controls within the uncertainties, suggesting that interactions do not play a significant role in inducing AGN activity in our sample. Finally, the star formation activity in dwarf AGN is only slightly lower than that in their control counterparts, suggesting that the presence of radiatively efficient AGN does not lead to significant, prompt quenching of star formation in these systems. [ABSTRACT FROM AUTHOR]

Recently, models of the quasar luminosity function (QLF) rooted on large observational compilations have been produced that, unlike their predecessors, feature a smooth evolution with time. This bypasses the need to assume an ionizing emissivity evolution when simulating helium reionization with observations-based QLF, thus yielding more robust constraints. We combine one such QLF with a cosmological hydrodynamical simulation and 3D multifrequency radiative transfer. The simulated reionization history is consistently delayed in comparison to most other models in the literature. The predicted intergalactic medium temperature is larger than the observed one at |$z \lesssim 3$|⁠. Through forward modelling of the He  ii Lyman  |$\alpha$| forest, we show that our model produces an extended helium reionization and successfully matches the bulk of the observed effective optical depth distribution, although it overionizes the Universe at |$z\lesssim 2.8$| as the effect of small-scale Lyman Limit Systems not being resolved. We thoroughly characterize transmission regions and dark gaps in He  ii Lyman  |$\alpha$| forest sightlines. We quantify their sensitivity to the helium reionization, opening a new avenue for further observational studies of this epoch. Finally, we explore the implications for helium reionization of the large number of active galactic nuclei revealed at |$z\gtrsim 5$| by JWST. We find that such modifications do not affect any observable at |$z\le 4$|⁠ , except in our most extreme model, indicating that the observed abundance of high- z AGNs does not bear consequences for helium reionization. [ABSTRACT FROM AUTHOR]

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

The size and complexity reached by the large sky spectroscopic surveys require efficient, accurate, and flexible automated tools for data analysis and science exploitation. We present the Galaxy Spectra Network/GaSNet-II, a supervised multinetwork deep learning tool for spectra classification and redshift prediction. GaSNet-II can be trained to identify a customized number of classes and optimize the redshift predictions. Redshift errors are determined via an ensemble/pseudo-Monte Carlo test obtained by randomizing the weights of the network-of-networks structure. As a demonstration of the capability of GaSNet-II, we use 260k Sloan Digital Sky Survey spectra from Data Release 16, separated into 13 classes including 140k galactic, and 120k extragalactic objects. GaSNet-II achieves 92.4 per cent average classification accuracy over the 13 classes and mean redshift errors of approximately 0.23 per cent for galaxies and 2.1 per cent for quasars. We further train/test the pipeline on a sample of 200k 4MOST (4-metre Multi-Object Spectroscopic Telescope) mock spectra and 21k publicly released DESI (Dark Energy Spectroscopic Instrument) spectra. On 4MOST mock data, we reach 93.4 per cent accuracy in 10-class classification and mean redshift error of 0.55 per cent for galaxies and 0.3 per cent for active galactic nuclei. On DESI data, we reach 96 per cent accuracy in (star/galaxy/quasar only) classification and mean redshift error of 2.8 per cent for galaxies and 4.8 per cent for quasars, despite the small sample size available. GaSNet-II can process ∼40k spectra in less than one minute, on a normal Desktop GPU. This makes the pipeline particularly suitable for real-time analyses and feedback loops for optimization of Stage-IV survey observations. [ABSTRACT FROM AUTHOR]

Environmental effects are believed to play an important yet poorly understood role in triggering accretion events onto the supermassive black holes (SMBHs) of galaxies (active galactic nuclei; AGNs). Massive clusters, which represent the densest structures in the Universe, provide an excellent laboratory to isolate environmental effects and study their impact on black hole growth. In this work, we critically review observational evidence for the preferential activation of SMBHs in the outskirts of galaxy clusters. We develop a semi-empirical model under the assumption that the incidence of AGN in galaxies is independent of environment. We demonstrate that the model is broadly consistent with recent observations on the AGN halo occupation at z = 0.2, although it may overpredict satellite AGN in massive haloes at that low redshift. We then use this model to interpret the projected radial distribution of X-ray sources around high redshift (z ≈ 1) massive (⁠|$\gt 5 \times 10^{14} \, M_\odot$|⁠) clusters, which show excess counts outside their virial radius. Such an excess naturally arises in our model as a result of sample variance. Up to 20  per cent of the simulated projected radial distributions show excess counts similar to the observations, which are however, because of background/foreground AGN and hence, not physically associated with the cluster. Our analysis emphasizes the importance of projection effects and shows that current observations of z ≈ 1 clusters remain inconclusive on the activation of SMBHs during infall. [ABSTRACT FROM AUTHOR]