This paper proposes a simple, empirically derived, unifying structure for the inner regions of quasars. This structure is constructed to explain the broad absorption line regions (BALRs) and the narrow "associated" ultraviolet and X-ray "ionized" absorbers (NALs) and is also found to explain the broad emission line regions (BELRs) and several scattering features, including a substantial fraction of the broad X-ray Fe-K emission line and the biconical extended narrow emission line region (ENLR) structures seen on large kiloparsec scales in Seyfert images. The model proposes that a funnel-shaped thin shell outflow creates all of these features. The wind arises vertically from a narrow range of radii on a disk at BELR velocities. Radiation force then accelerates the flow radially, so that it bends outward to a cone angle of ~60° and has a divergence angle of ~6°, to give a covering factor of ~10%. When the central continuum is viewed from the side, through this wind, narrow high-ionization "associated" ultraviolet absorption lines and the X-ray "ionized absorbers" are seen, as in many low-luminosity active galactic nuclei (AGNs). When viewed end-on, the full range of velocities is seen in absorption with a large total column density, giving rise to the broad absorption line systems seen in a minority of quasars, the BAL QSOs. The wind is both warm (~106 K) and highly ionized. This warm highly ionized medium (WHIM) has a density of ~109 cm-3, putting it in pressure equilibrium with the BELR clouds; the BELR is then a cool phase embedded in the overall outflow, avoiding cloud destruction through shear. The wind has the correct ionization parameter and filling factor for this. The high- and low-ionization zones of the BELR correspond to the cylindrical and conical regions of the wind, since the former is exposed to the full continuum while the latter receives only the continuum filtered by the former. The warm wind is significantly Thomson thick along the radial flow direction, producing the polarized optical continuum found in BALs, but is only partially ionized, creating a broad fluorescent 6.4 keV Fe-K emission line and greater than 10 keV Compton hump. The conical shell outflow can produce a biconical matter-bounded NELR. Luminosity-dependent changes in the structure, reducing the cylindrical part of the flow or increasing the mean angle to the disk axis and decreasing the wind opening angle, may explain the UV and X-ray Baldwin effects and the greater prevalence of obscuration in low-luminosity AGNs.

https://iopscience.iop.org/article/10.1086/317778/pdf

A Structure for Quasars

Meteorite chronometry based on the 182Hf–182W system can provide powerful constraints on the timing of planetary accretion and differentiation1,2,3,4, although the full potential of this method has yet to be realized. For example, no measurements have been made on the silicate-rich portions of planets and planetesimals other than the Earth and Moon. Here we report tungsten isotope compositions for two eucrites, thought to be derived from asteroid 4 Vesta, and from eight other basaltic achondritic meteorites that are widely considered to be from Mars. The eucrites, which are among the oldest differentiated meteorites, yield exceedingly radiogenic tungsten, indicating rapid accretion, differentiation and core formation on Vesta within the first 5–15 Myr of Solar System history, whereas the range of radiogenic tungsten measurements on the martian meteorites points towards tungsten depletion via melting and core formation within the first 30 Myr of the Solar System. The survival of tungsten isotope heterogeneity in the martian upper mantle implies that no giant impacts or large-scale convective mixing took place since this time. These results contrast with those obtained for the Earth–Moon system2,3 for which accretion and core formation related to giant impacts appears to have continued for at least an additional 20 Myr.

/pdf/core-formation-on-mars-and-differentiated-asteroids-26e0up96kt.pdf

Core formation on Mars and differentiated asteroids

We present an updated and improved Mbh–σ diagram containing 64 galaxies for which Mbh measurements (not just upper limits) are available. Because of new and increased black hole masses at the high-mass end, and a better representation of barred galaxies at the low-mass end, the ‘classical’ (all morphological type) Mbh–σ relation for predicting black hole masses is log (Mbh/M⊙) = (8.13 ± 0.05) + (5.13 ± 0.34)log [σ/200 km s−1], with an rms scatter of 0.43 dex. Modifying the regression analysis to correct for a hitherto overlooked sample bias in which black holes with masses <106 M⊙ are not (yet) detectable, the relation steepens further to give log (Mbh/M⊙) = (8.15 ± 0.06) + (5.95 ± 0.44)log [σ/200 km s−1]. We have also updated the ‘barless’ and ‘elliptical-only’Mbh–σ relations introduced by Graham and Hu in 2008 due to the offset nature of barred galaxies. These relations have a total scatter as low as 0.34 dex and currently define the upper envelope of points in the Mbh–σ diagram. They also have a slope consistent with a value 5, in agreement with the prediction by Silk & Rees based on feedback from massive black holes in bulges built by monolithic collapse.



Using updated virial products and velocity dispersions from 28 active galactic nuclei, we determine that the optimal scaling factor f– which brings their virial products in line with the 64 directly measured black hole masses – is 2.8+0.7−0.5. This is roughly half the value reported by Onken et al. and Woo et al., and consequently halves the mass estimates of most high-redshift quasars. Given that barred galaxies are, on average, located ∼0.5 dex below the ‘barless’ and ‘elliptical-only’Mbh–σ relations, we have explored the results after separating the samples into barred and non-barred galaxies, and we have also developed a preliminary corrective term to the velocity dispersion based on bar dynamics. In addition, given the recently recognized coexistence of massive black holes and nuclear star clusters, we present the first ever (Mbh+Mnc)–σ diagram and begin to explore how galaxies shift from their former location in the Mbh–σ diagram.

https://researchbank.swinburne.edu.au/file/4859a5d7-a62f-40b2-98a1-a5084b3ee946/1/PDF (Accepted manuscript).pdf

An expanded Mbh–σ diagram, and a new calibration of active galactic nuclei masses

We have made the first VLBI synthesis images of the H2O maser emission associated with the central engine of the Seyfert galaxy NGC 1068. Emission extends about ±300 km s-1 from the systemic velocity. Images with sub-milliarcsecond angular resolution show that the redshifted emission lies along an arc to the northwest of the systemic emission. (The blueshifted emission has not yet been imaged with VLBI.) Based on the maser velocities and the relative orientation of the known radio jet, we propose that the maser emission arises on the surface of a nearly edge-on torus, where physical conditions are conducive to maser action. The visible part of the torus is axially thick, with comparable height and radius. The velocity field indicates sub-Keplerian differential rotation around a central mass of ~1 × 107 M☉ that lies within a cylindrical radius of about 0.65 pc. The estimated luminosity of the central engine is about 0.5 of the Eddington limit. There is no detectable compact radio continuum emission near the proposed center of the torus (TB < 5 × 106 K on size scales of ~0.1 pc), so that the observed flat-spectrum core cannot be direct self-absorbed synchrotron radiation.

https://iopscience.iop.org/article/10.1086/310346/pdf

Vlbi imaging of water maser emission from the nuclear torus of ngc 1068

We investigate the correlation between the supermassive black holes (SMBHs) mass (Mbh) and the stellar velocity dispersion ( ) in two types of host galaxies: the early-type bulges (disk galaxies with classical bulges or elliptical galaxies) and pseudobulges. In the form log(Mbh=M ) = + log( =200 km s 1 ), the best-fit results for the 39 early-type bulges are the slope = 4:06 0:28 and the normalization = 8:28 0:05; the best-fit results for the 9 pseudobulges are = 4:5 1:3, = 7:50 0:18. Both relations have intrinsic scatter in logMbh of .0.27 dex. The Mbh- relation for pseudobulges is different from the relation in the early-type bulges over the 3 significance level. The contrasting relations indicate the formation and growth histories of SMBHs depend on their host type. The discrepancy between the slope of the Mbh- relations using different definition of velocity dispersion vanishes in our sample, a uniform slope will constrain the coevolution theories of the SMBHs and their host galaxies more effectively. We also find the slope for the “core” elliptical galaxies at the high mass range of the relation appears steeper ( ’ 5-6), which may be the imprint of their origin of dissipationless mergers.

The black hole mass–stellar velocity dispersion correlation: bulges versus pseudo-bulges

We present the results of further Hubble Space Telescope (HST) imaging polarimetry of the inner region of NGC 1068 taken with the COSTAR corrected Faint Object Camera (FOC) in the ultraviolet (2400-2700 A). The centro-symmetric polarization pattern revealed by previous HST imaging polarimetry is shown to extend even closer to the illumination source (the hidden nucleus). Even in the inner region the ultraviolet light is dominated by scattered radiation, as the average polarization is approximately 20%, and it can be as high as 65%, figures which are similar to those obtained previously at larger radii. These new data allow a more accurate determination of the position of the source of scattered radiation that is displaced by 020 north and 006 west from the position recently obtained by Capetti et al. This new location of the nucleus rules out both cloud B and the "twin-crescent" as the nucleus of NGC 1068. In agreement with the unified model for Seyfert galaxies, there appears to be no visible counterpart at this location. The good agreement with previous polarimetric observations demonstrates the integrity of the polarization capabilities of the FOC obtained after the installation of COSTAR.

Hubble Space Telescope Imaging Polarimetry of the Inner Nuclear Region of NGC 1068

We present the results of a campaign to obtain an accurate registration of Hubble Space Telescope (HST) and MERLIN images of NGC 1068, the prototypical Seyfert 2 galaxy. The final registration is accurate to 100 mas. A strong anticorrelation between radio and optical emission is revealed; in particular, the radio jet lies on a region of relatively low optical emission and is surrounded by line-emitting clouds. A major exception is the brightest narrow-line region (NLR) knot, cloud B, which lies, at least in projection, along the radio jet. These results can be understood as due to the interaction between the jet and the surrounding medium: in this scenario, the outflowing plasma is sweeping and heating the interstellar gas. As a result of this interaction and compression, the line emission is highly enhanced along the edges of the radio jet. It therefore appears that the morphology of the NLR of NGC 1068 is dominated by the presence of a radio outflow, as already revealed by HST observations of several Seyfert galaxies with extended radio emission. The optical peak seen in the HST images is located at α = 02h42m40711, δ = -00°00'4781 (J2000, FK5), with an error of 80 mas. The hidden nucleus, as determined by HST imaging polarimetry, falls at α = 02h42m40710, δ = -00°00'4811 (J2000, FK5). It is offset toward the south (i.e., along the radio axis) with respect to the two southernmost radio components and, in particular, by 170 mas from the inverted spectrum radio component, S1. This does not rule out that S1 is indeed the radio core but suggests that the nucleus of NGC 1068 might be radio silent, or its emission absorbed at radio wavelengths also. There are several contributions to the final accuracy of the optical-to-radio registration. A significant decrease of the astrometric error budget has to wait for substantial improvements, like those expected from the radio-optical link in the forthcoming HIPPARCOS catalog.

The Nuclear Region of NGC 1068: High-Accuracy Alignment of the Optical and Radio Emission

The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive ellipticals. We have analyzed Hubble Space Telescope archival images of 14 nearby core ellipticals, finding evidence for small (≲ 10 pc) displacements between the active galactic nucleus (AGN; the location of the SBH) and the center of the galaxy (the mean photocenter) in 10 of them. Excluding objects that may be affected by large-scale isophotal asymmetries, we consider six galaxies to have detected displacements, including M87, where a displacement was previously reported by Batcheldor et al. In individual objects, these displacements can be attributed to residual gravitational recoil oscillations following a major or minor merger within the last few gigayears. For plausible merger rates, however, there is a high probability of larger displacements than those observed, if SBH coalescence took place in these galaxies. Remarkably, the AGN-photocenter displacements are approximately aligned with the radio source axis in four of the six galaxies with displacements, including three ofmore » the four having relatively powerful kiloparsec-scale jets. This suggests intrinsic asymmetries in radio jet power as a possible displacement mechanism, although approximate alignments are also expected for gravitational recoil. Orbital motion in SBH binaries and interactions with massive perturbers can produce the observed displacement amplitudes but do not offer a ready explanation for the alignments.« less

http://iopscience.iop.org/article/10.1088/0004-637X/795/2/146/pdf

Recoiling supermassive black holes: a search in the nearby universe

We present the results of Hubble Space Telescope (HST) and MERLIN observations of the Seyfert 1.5 galaxy Mrk 6. FOC/HST images reveal a jetlike feature in the emission line which extends ~05, or 250 pc, from the nucleus. The optical jet is cospatial with the southern radio jet, as revealed by a 6 cm MERLIN image matching the HST angular resolution, and shares with it a similar curved morphology. The emission-line jet shows a low-ionization halo surrounding a higher ionization core. This suggests that the optical jet is generated by the expansion of a halo of hot material around the radio jet. Most of the radio and optical emission originates in the innermost 110 pc, which suggests that radio and optical emission are closely associated on this small scale. These results strongly support the interpretation that the structure of the narrow-line region of Mrk 6, and of Seyfert galaxies with known linear radio sources, is dominated by the interaction between the radio ejecta and the surrounding medium.

A. Capetti

Papers

Hubble Space Telescope Imaging Polarimetry of the Inner Nuclear Region of NGC 1068

The Nuclear Region of NGC 1068: High-Accuracy Alignment of the Optical and Radio Emission

Recoiling supermassive black holes: a search in the nearby universe

The Emission-Line Jet in Markarian 6*

Recoiling Supermassive Black Holes: a search in the Nearby Universe