We determine the extinction curve in the z l = 0.83 lens galaxy of the gravitational lens SBS0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images (z s = 1.38) from 3400 to 9200 Å. It is the first measurement of an extinction curve at a cosmological distance of comparable quality to those obtained within the Galaxy. The extinction curve has a strong 2175 Å feature, a noteworthy fact because it has been weak or non-existent in most estimates of extinction curves outside the Galaxy. The extinction curve is fitted well by a standard R V = 2.1 ± 0.9 Galactic extinction curve. If we assume standard Galactic extinction laws, the estimated dust redshift of z = 0.88 ± 0.02 is in good agreement with the spectroscopic redshift of the lens galaxy. The widespread assumption that SMC extinction curves are more appropriate models for cosmological dust may be incorrect.

We present the first results of the Galaxy Activity, Torus, and Outflow Survey (GATOS), a project aimed at understanding the properties of the dusty molecular tori and their connection to the host galaxy in nearby Seyfert galaxies. Our project expands the range of active galactic nuclei (AGN) luminosities and Eddington ratios covered by previous surveys of Seyferts conducted by the Atacama Large Millimeter Array (ALMA), allowing us to study the gas feeding and feedback cycle in a combined sample of 19 Seyferts. We used ALMA to obtain new images of the emission of molecular gas and dust using the CO(3–2) and HCO+(4–3) lines as well as their underlying continuum emission at 870 μm with high spatial resolutions (0.1″ ∼ 7 − 13 pc) in the circumnuclear disks (CND) of ten nearby (D < 28 Mpc) Seyfert galaxies selected from an ultra-hard X-ray survey. Our new ALMA observations detect 870 μm continuum and CO line emission from spatially resolved disks located around the AGN in all the sources. The bulk of the 870 μm continuum flux can be accounted for by thermal emission from dust in the majority of the targets. For most of the sources, the disks show a preponderant orientation perpendicular to the AGN wind axes, as expected for dusty molecular tori. The median diameters and molecular gas masses of the tori are ∼42 pc and ∼6 × 105 M⊙, respectively. We also detected the emission of the 4–3 line of HCO+ in four GATOS targets. The order of magnitude differences found in the CO/HCO+ ratios within our combined sample point to a very different density radial stratification inside the dusty molecular tori of these Seyferts. We find a positive correlation between the line-of-sight gas column densities responsible for the absorption of X-rays and the molecular gas column densities derived from CO toward the AGN in our sources. Furthermore, the median values of both column densities are similar. This suggests that the neutral gas line-of-sight column densities of the dusty molecular tori imaged by ALMA significantly contribute to the obscuration of X-rays. The radial distributions of molecular gas in the CND of our combined sample show signs of nuclear-scale molecular gas deficits. We also detect molecular outflows in the sources that show the most extreme nuclear-scale gas deficits in our sample. These observations find for the first time supporting evidence that the imprint of AGN feedback is more extreme in higher luminosity and/or higher Eddington ratio Seyfert galaxies.

No abstract

We have combined observations of the Antennae galaxies from the radio interferometer ALMA (Atacama Large Millimeter/submillimeter Array) and from the optical interferometer GHαFaS (Galaxy Hα Fabry-Perot System). The two sets of observations have comparable angular and spectral resolutions, enabling us to identify 142 giant molecular clouds (GMCs) and 303 Hii regions. We have measured, and compared, their basic physical properties (radius, velocity dispersion, luminosity). For the Hii regions, we find two physical regimes, one for masses > 10 5.4 M ⊙ of ionized gas, where the gas density increases with gas mass, the other for masses < 10 5.4 M ⊙ of ionized gas, where the gas density decreases with gas mass. For the GMCs, we find, in contrast to previous studies in other galaxies over a generally lower mass range of clouds, that the gas surface density increases with the radius, hinting at two regimes for these clouds if we consider both sources of data. We also find that the GMC mass function has a break at 10 6.7 M ⊙ . Using the velocity dispersion measurements, we claim that the difference between the regimes is the nature of the dominant binding force. For the regions in the lower mass range, the dominant force is the external pressure, while in the higher mass range it is the internal gravity of the clouds. In the regime where gravity is dominant, the star formation rate, derived from the dust-corrected Hα luminosity, increases super-linearly with the velocity dispersion, and the gas density increases with the gas mass.