The power of jets from black holes is expected to depend on both the spin of the black hole and the structure of the accretion disc in the region of the last stable orbit. We investigate these ...dependencies using two different physical models for the jet power: the classical Blandford–Znajek (BZ) model and a hybrid model developed by Meier. In the BZ case, the jets are powered by magnetic fields directly threading the spinning black hole while in the hybrid model, the jet energy is extracted from both the accretion disc as well as the black hole via magnetic fields anchored to the accretion flow inside and outside the hole's ergosphere. The hybrid model takes advantage of the strengths of both the Blandford–Payne and BZ mechanisms, while avoiding the more controversial features of the latter. We develop these models more fully to account for general relativistic effects and to focus on advection-dominated accretion flows (ADAFs) for which the jet power is expected to be a significant fraction of the accreted rest mass energy. We apply the models to elliptical galaxies, in order to see if these models can explain the observed correlation between the Bondi accretion rates and the total jet powers. For typical values of the disc viscosity parameter α∼ 0.04 –0.3 and mass accretion rates consistent with ADAF model expectations, we find that the observed correlation requires j≳ 0.9; that is, it implies that the black holes are rapidly spinning. Our results suggest that the central black holes in the cores of clusters of galaxies must be rapidly rotating in order to drive jets powerful enough to heat the intracluster medium and quench cooling flows.
ABSTRACT
We present a dynamical study of the narrow-line regions in two nearby type 2 quasars (QSO2s). We construct dynamical models based on detailed photoionization models of the emission-line gas, ...including the effects of internal dust, to apply to observations of large-scale outflows from these active galactic nuclei (AGNs). We use Mrk 477 and Mrk 34 in order to test our models against recent Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) observations of O iii emission-line kinematics, since these AGNs possess more energetic outflows than found in Seyfert galaxies. We find that the outflows within 500 pc are consistent with radiative acceleration of dusty gas, however the outflows in Mrk 34 are significantly more extended and may not be directly accelerated by radiation. We characterize the properties of X-ray winds found from the expansion of O iii-emitting gas close to the black hole. We show that such winds possess the kinetic energy density to disturb O iii gas at ∼1.8 kpc, and have sufficient energy to entrain the O iii clouds at ∼1.2 kpc. Assuming that the X-ray wind possesses the same radial mass distribution as the O iii gas, we find that the peak kinetic luminosity for this wind is 2 per cent of Mrk 34’s bolometric luminosity, which is in the 0.5–5 per cent range required by some models for efficient feedback. Our work shows that, although the kinetic luminosity as measured from O iii-emitting gas is frequently low, X-ray winds may provide more than one order of magnitude higher kinetic power.
Abstract
We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14–195 keV luminosities LX ≥ 1041.5 erg s−1, redshift z ≤ 0.015, being accessible for observations ...with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended O iiiλ5007 emission. Our goal is to study Active Galactic Nucleus (AGN) feeding and feedback processes from near-infrared integral-field spectra, which include both ionized (H ii) and hot molecular (H2) emission. This sample is complemented by other nine Seyfert galaxies previously observed with NIFS. We show that the host galaxy properties (absolute magnitudes MB, MH, central stellar velocity dispersion and axial ratio) show a similar distribution to those of the 69 BAT AGN. For the 20 galaxies already observed, we present surface mass density (Σ) profiles for H ii and H2 in their inner ∼500 pc, showing that H ii emission presents a steeper radial gradient than H2. This can be attributed to the different excitation mechanisms: ionization by AGN radiation for H ii and heating by X-rays for H2. The mean surface mass densities are in the range (0.2 ≤ ΣH ii ≤ 35.9) M⊙ pc−2, and (0.2 ≤ ΣH2 ≤ 13.9)× 10−3 M⊙ pc−2, while the ratios between the H ii and H2 masses range between ∼200 and 8000. The sample presented here will be used in future papers to map AGN gas excitation and kinematics, providing a census of the mass inflow and outflow rates and power as well as their relation with the AGN luminosity.
ABSTRACT
The merger remnant NGC 34 is a local luminous infrared galaxy (LIRG) hosting a nuclear starburst and a hard X-ray source associated with a putative, obscured Seyfert 2 nucleus. In this work, ...we use adaptive optics assisted near-infrared (NIR) integral field unit observations of this galaxy to map the distribution and kinematics of the ionized and molecular gas in its inner $\mathrm{1.2\, kpc \times 1.2\, kpc}$, with a spatial resolution of 70 pc. The molecular and ionized gas kinematics is consistent with a disc with projected major axis along a mean PA = −9${_{.}^{\circ}}$2 ± 0${_{.}^{\circ}}$9. Our main findings are that NGC 34 hosts an AGN and that the nuclear starburst is distributed in a circumnuclear star formation ring with inner and outer radii of ≈ 60 and 180 pc, respectively, as revealed by maps of the $\mathrm{Fe\, {\small {II}} / Pa\,\beta }$ and H2/Br γ emission-line ratios, and corroborated by PCA tomography analysis. The spatially resolved NIR diagnostic diagram of NGC 34 also identifies a circumnuclear structure dominated by processes related to the stellar radiation field and a nuclear region where $\rm Fe\, {\small {II}}$ and H2 emissions are enhanced relative to the hydrogen recombination lines. We estimate that the nuclear X-ray source can account for the central H2 enhancement and conclude that $\rm Fe\, {\small {II}}$ and H2 emissions are due to a combination of photoionization by young stars, excitation by X-rays produced by the AGN and shocks. These emission lines show nuclear, broad, blueshifted components that can be interpreted as nuclear outflows driven by the AGN.
Abstract
We present a multiwavelength study of the OH megamaser galaxy IRAS17526 + 3253, based on new Gemini multi-object spectrograph integral field unit (GMOS/IFU) observations, Hubble Space ...Telescope F814W, and H α + N ii images, and archival 2MASS and 1.49 GHz VLA data. The Hubble Space Telescope(HST) images clearly reveal a mid-to-advanced stage major merger whose northwestern and southeastern nuclei have a projected separation of ∼8.5 kpc. Our HST/H α + N ii image shows regions of ongoing star formation across the envelope on ∼10 kpc scales, which are aligned with radio features, supporting the interpretation that the radio emission originates from star-forming regions. The measured H α luminosities imply that the unobscured star formation rate (SFR) is ∼10–30 M⊙ yr−1. The GMOS/IFU data reveal two structures in northwestern separated by 850 pc and by a discontinuity in the velocity field of ∼ 200 km s−1. We associate the blueshifted and redshifted components with, respectively, the distorted disc of northwestern and tidal debris, possibly a tail originating in southeastern. Star formation is the main ionization source in both components, which have SFRs of ∼2.6–7.9 M⊙ yr−1 and ∼1.5–4.5 M⊙ yr−1, respectively. Fainter line emission bordering these main components is consistent with shock ionization at a velocity ∼200 km s−1 and may be the result of an interaction between the tidal tail and the northwestern galaxy’s disc. IRAS17526 + 3253 is one of only a few systems known to host both luminous OH and H2O masers. The velocities of the OH and H2O maser lines suggest that they are associated with the northwestern and southeastern galaxies, respectively (Martin et al.; Wagner).
Abstract
We present a near-infrared (near-IR) study of the spectral components of the continuum in the inner 500 × 500 pc2 of the nearby Seyfert galaxy Mrk 573 using adaptive optics near-IR integral ...field spectroscopy with the instrument near-infrared integral field spectrograph of the Gemini North Telescope at a spatial resolution of ∼50 pc. We performed spectral synthesis using the starlight code and constructed maps for the contributions of different age components of the stellar population: young (age ≤100 Myr), young–intermediate (100 < age ≤ 700 Myr), intermediate–old (700 Myr < age ≤ 2 Gyr) and old (age > 2 Gyr) to the near-IR K-band continuum, as well as their contribution to the total stellar mass. We found that the old stellar population is dominant within the inner 250 pc, while the intermediate-age components dominate the continuum at larger distances. A young stellar component contributes up to ∼20 per cent within the inner ∼70 pc, while hot dust emission and featureless continuum components are also necessary to fit the nuclear spectrum, contributing up to 20 per cent of the K-band flux there. The radial distribution of the different age components in the inner kiloparsec of Mrk 573 is similar to those obtained by our group for the Seyfert galaxies Mrk 1066, Mrk 1157 and NGC 1068 in previous works using a similar methodology. Young stellar populations (≤100 Myr) are seen in the inner 200–300 pc for all galaxies contributing with ≥20 per cent of the K-band flux, while the near-IR continuum is dominated by the contribution of intermediate-age stars (t = 100 Myr–2 Gyr) at larger distances. Older stellar populations dominate in the inner 250 pc.
We analyze new high spatial resolution (~60 pc) ALMA CO(2−1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d = 48 Mpc) in combination with ancillary Hubble Space Telescope ...optical and near infrared (IR) imaging, as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (~450 km s-1) spatially resolved (size~2.5 kpc; dynamical time ~3 Myr) massive (~107 M⊙; Ṁ ~ 2−8 M⊙ yr-1) molecular outflow that has originated in the central ~250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 105.5 and 106.4 M⊙. The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (~100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7 × 10-5, which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow. The nuclear IR and radio properties are compatible with strong and highly obscured star-formation (Ak ~ 4.6 mag; star formation rate ~ 15 M⊙ yr-1). We do not find any evidence for the presence of an active galactic nucleus. We estimate that supernova explosions in the nuclear starburst (νSN ~ 0.2 yr-1) can power the observed molecular outflow. The kinetic energy and radial momentum of the cold molecular phase of the outflow correspond to about 2% and 20%, respectively, of the supernovae output. The cold molecular outflow velocity is lower than the escape velocity, so the gas will likely return to the galaxy disk. The mass loading factor is ~0.1−0.5, so the negative feedback owing to this star-formation-powered molecular outflow is probably limited.
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