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We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of the angular Einstein radius θ _E = 0.724 ± 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses of M _1 = 0.258 ± 0.008 M _⊙ and M _2 = 0.130 ± 0.007 M _⊙ , a projected separation of r _⊥ = 6.83 ± 0.31 au, and a distance of D _L = 2.29 ± 0.08 kpc. The successful VLTI observations of ASASSN-22av open up a new path for studying intermediate-separation (i.e., a few astronomical units) stellar-mass binaries, including those containing dark compact objects such as neutron stars and stellar-mass black holes.

We explore the relationship between X-ray absorption and optical obscuration within the BAT AGN Spectroscopic Survey (BASS), which has been collecting and analyzing the optical and X-ray spectra for 641 hard X-ray selected (E > 14 keV) active galactic nuclei (AGNs). We use the deviation from a linear broad Hα-to-X-ray relationship as an estimate of the maximum optical obscuration toward the broad line region (BLR) and compare the AV to the hydrogen column densities () found through systematic modeling of their X-ray spectra. We find that the inferred columns implied by AV toward the BLR are often orders of magnitude less than the columns measured toward the X-ray emitting region, indicating a small-scale origin for the X-ray absorbing gas. After removing 30% of Sy 1.9s that potentially have been misclassified due to outflows, we find that 86% (164/190) of the Type 1 population (Sy 1–1.9) are X-ray unabsorbed as expected based on a single obscuring structure. However, 14% (26/190), of which 70% (18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting that the BLR itself is providing extra obscuration toward the X-ray corona. The fraction of X-ray absorbed Type 1 AGNs remains relatively constant with AGN luminosity and Eddington ratio, indicating a stable BLR covering fraction. [ABSTRACT FROM AUTHOR]

We present 90 mas (37 pc) resolution ALMA imaging of Arp 220 in the CO (1-0) line and continuum at . The internal gas distribution and kinematics of both galactic nuclei are well resolved for the first time. In the west nucleus, the major gas and dust emission extends out to 0.″2 radius (74 pc); the central resolution element shows a strong peak in the dust emission but a factor of 3 dip in the CO line emission. In this nucleus, the dust is apparently optically thick () at with a dust brightness temperature of ∼147 K. The column of interstellar matter at this nucleus is cm−2, corresponding to ∼900 gr cm−2. The east nucleus is more elongated with radial extent 0.″3 or ∼111 pc. The derived kinematics of the nuclear disks provide a good fit to the line profiles, yielding the emissivity distributions, the rotation curves, and velocity dispersions. In the west nucleus, there is evidence of a central Keplerian component requiring a central mass of 8 × 108 . The intrinsic widths of the emission lines are (west) and 120 (east) km s−1. Given the very short dissipation timescales for turbulence (≲105 years), we suggest that the line widths may be due to semicoherent motions within the nuclear disks. The symmetry of the nuclear disk structures is impressive, implying the merger timescale is significantly longer than the rotation period of the disks. [ABSTRACT FROM AUTHOR]

We present the Atacama Large Millimeter/submillimeter Array survey of CO(2–1) emission from the 1/5 solar metallicity, Local Group dwarf galaxy NGC 6822. We achieve high ( pc) spatial resolution while covering a large area: four 250 pc × 250 pc regions that encompass of NGC 6822's star formation. In these regions, we resolve compact CO clumps that have small radii (∼2–3 pc), narrow line width ( km s−1), and low filling factor across the galaxy. This is consistent with other recent studies of low-metallicity galaxies, but here shown with a larger sample. At parsec scales, CO emission correlates with emission better than with emission and anticorrelates with Hα, so that polycyclic aromatic hydrocarbon emission may be an effective tracer of molecular gas at low metallicity. The properties of the CO clumps resemble those of similar-size structures in Galactic clouds except of slightly lower surface brightness and with CO-to-H2 ratio ∼1–2× the Galactic value. The clumps exist inside larger atomic–molecular complexes with masses typical for giant molecular clouds. Using dust to trace H2 for the entire complex, we find the CO-to-H2 ratio to be the Galactic value, but with strong dependence on spatial scale and variations between complexes that may track their evolutionary state. The H2-to-H i ratio is low globally and only mildly above unity within the complexes. The ratio of star formation rate to H2 is higher in the complexes than in massive disk galaxies, but after accounting for the bias from targeting star-forming regions, we conclude that the global molecular gas depletion time may be as long as in massive disk galaxies. [ABSTRACT FROM AUTHOR]