Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1909.08639

Redefining the torus: A unifying view of AGN in the infrared and sub-mm

Sebastian F. Hönig
View original source ↗Read source document ↗Export metadata ↓

Abstract

The advent of high-angular resolution IR and sub-mm interferometry allows for spatially-resolved observations of the parsec-scale environment of active galactic nuclei (AGN), commonly referred to as the "torus." While molecular lines show the presence of large, massive disks, the IR observations appear to be dominated by a strong polar component that has been interpreted as a dusty wind. This paper aims at using characteristics shared by AGN in each of the wavebands and a set of simple physical principles to form a unifying view of these seemingly contradictory observations: Dusty molecular gas flows in from galactic scales of ~100 pc to the sub-parsec environment via a disk with small to moderate scale height. The hot, inner part of the disk puffs up due to IR radiation pressure and unbinds a large amount of the inflowing gas from the black hole's gravitational potential, providing the conditions to launch a wind driven by the radiation pressure from the AGN. The dusty wind feeds back mass into the galaxy at a rate of the order of ~0.1-100 $M_\odot$/yr, depending on AGN luminosity and Eddington ratio. Angle-dependent obscuration as required by AGN unification is provided by a combination of disk, wind, and wind launching region.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sebastian F. Hönig. 2019-09-18. Redefining the torus: A unifying view of AGN in the infrared and sub-mm. https://doi.org/10.3847/1538-4357%2Fab4591

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Dark matter haloes from dwarf to massive galaxies: no systematic inner-density tension with ΛCDM hydrodynamical simulations

Two of the most prominent small-scale challenges to the cold dark matter (CDM) paradigm are the cusp-core and diversity-of-rotation-curves problems. The former concerns the shallow inner DM density profiles inferred for many galaxies compared with the cusps predicted by collisionless CDM, while the latter concerns the wider range of inner DM densities and rotation curve shapes inferred observationally than hydrodynamical simulations traditionally reproduce. Robust observational constraints on DM core sizes and halo densities are therefore essential for testing both the nature of DM and the impact of galaxy formation processes. We analyse the inner DM distribution of a curated sample of 48 gas-rich galaxies and 8 Milky Way gas-poor satellites, spanning 6 orders of magnitude in $M_\ast$. We find substantial scatter in DM core sizes and degrees of coreness, with both cuspy and cored haloes occurring over a broad $M_\ast$ range. The cores are energetically consistent with stellar feedback, requiring modest supernova energy coupling efficiencies of order $0.1-1\%$. Comparisons with the NIHAO, FIRE-2, and EDGE simulations reveal broad agreement in the inner DM densities and logarithmic slopes of observed and simulated galaxies. The main residual differences concern the steep slopes of some massive simulated galaxies and differences in SHMRs. Using a rotation-curve diversity diagnostic from previous work, we find that extreme discrepancies with simulations are absent from our curated sample and largely attributable to uncertain kinematics or baryonic mass distributions. Within the scope of our analysis, we find no evidence of a systematic inner-density tension between our galaxy sample and current $Λ$CDM hydrodynamical simulations. Together with the modest energetic requirements for core formation, this substantially alleviates the cusp-core and diversity-of-rotation-curves problems.

astro-ph.GA↗
arXiv2026

High-z galaxies with the JWST and the ELT: Toward Ever-finer Detail

The exploration of the early Universe is being transformed by the James Webb Space Telescope (JWST), which delivers unprecedented angular resolution at infrared wavelengths and opens a unique window redward of the K band (2um). Thanks to NIRCam, NIRISS, NIRSpec, and MIRI instruments, which provide both imaging and spectroscopy with exquisite efficiency, new classes of sources have emerged within the first years of operations. The first half-Gyr of cosmic time is now routinely probed, revealing massive blue/red galaxies and a population of Active Galactic Nuclei (AGN) appearing as "little red dots" together with a rest-frame near-infrared/optical view of sources across the reionization and post-reionization epochs. Angular resolution will remain pivotal in the 2030s - 2040s, when extreme adaptive optics (AO) facilities will be deployed on both (8 - 10)m (e.g., the VLT Multi-Conjugate-Adaptive-Optics (MCAO) - Assisted Visible Imager and Spectrograph, MAVIS) and on extremely large telescopes, like the 39m ELT (e.g., Multi-conjugate adaptive Optics Relay For ELT Observation, MORFEO). Operating at the diffraction limit, these facilities will improve JWST's resolution, with ELT achieving a factor of ~ 6 smaller Point-Spread-Function (PSF). An ELT diffraction-limited PSF (with a Full Width Half Maximum, FWHM ~ 8-12 mas) in the near infrared will resolve spatial scales <100 pc at any redshift (z ~< 18), revealing abundant star-forming clumps with sufficient sensitivity. Leveraging gravitational lensing as a cosmic telescope, even with moderate magnification factors (mu ~ 4-8), diffraction-limited 8m and 39m telescopes will probe physical scales ~< 25 pc, enabling systematic studies of star formation down to star-cluster scale at cosmological distances. Such observations are poised to become routine in the 2030s - 2040s.

astro-ph.GA↗
arXiv2026

Mass-Dependent Dark Matter Deficit from Inelastic Scattering

Recent stellar-kinematic and neutral-hydrogen observations indicate a dark matter deficit within the central tens of kiloparsecs of nearby galaxies that grows systematically with stellar mass relative to hydrodynamical simulations. We show that this mass dependence can arise from exothermic inelastic dark matter with strongly velocity-dependent scattering. Two nearly degenerate dark matter states interact through vector and scalar mediators with opposite-sign contributions and unequal ranges. The resulting coupled-channel dynamics suppresses $s$-wave conversion at low velocity while retaining a $p$-wave enhancement at several hundred $\rm km/s$, where down-scattering injects kinetic energy and lowers central dark matter densities. At dwarf velocities, conversion remains suppressed while elastic scattering can still drive core formation consistent with the observed dwarf-clustering pattern. A late dark-sector phase transition, along with the low-velocity suppression, preserves a large excited-state fraction until halo formation. Using representative halos spanning the four observed stellar-mass bins, we find that the model accounts for the inferred dark matter deficit in all four bins, including its systematic growth with stellar mass, while its impact weakens toward cluster velocities. The growing discrepancy with hydrodynamical simulations may therefore offer a glimpse of previously hidden dark matter microphysics.

astro-ph.GA↗