C. M. V. Impellizzeri

THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0. ′′ 075 (10 AU) to 0. ′′ 025 (3.5 AU), revealing an astonishing level of detail in the cir cumstellar disk surrounding the young solar analogue HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46.72 ◦ ± 0.05 ◦ ) and position angle (+138.02 ◦ ± 0.07 ◦ ). We obtain a high-fidelity image of the 1.0 mm spectral index (�), which ranges from � � 2.0 in the optically-thick central peak and two brightest ring s, increasing to 2.3-3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation incl ude an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO + (1-0) which exhibits a pattern over LSR velocities from 2-12 km s -1 consistent with Keplerian motion around a �1.3M⊙ star, although complicated by absorption at low blue-shifted velocities. We also serendipitously detect and resolve the nearby protost ars XZ Tau (A/B) and LkH�358 at 2.9 mm. Subject headings: stars: individual (HL Tau, XZ Tau, LkH�358) — protoplanetary disks — stars: formation — submillimeter: planetary systems — techniques: interferometric

The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks

Observations of H_2O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project (MCP) allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry images and kinematics of water maser emission in six active galaxies: NGC 1194, NGC 2273, NGC 2960 (Mrk 1419), NGC 4388, NGC 6264 and NGC 6323. We use the Keplerian rotation curves of these six megamaser galaxies, plus a seventh previously published, to determine accurate enclosed masses within the central ~0.3 pc of these galaxies, smaller than the radius of the sphere of influence of the central mass in all cases. We also set lower limits to the central mass densities of between 0.12 × 10^(10) and 61 × 10^(10) M_⊙ pc^(–3). For six of the seven disks, the high central densities rule out clusters of stars or stellar remnants as the central objects, and this result further supports our assumption that the enclosed mass can be attributed predominantly to a supermassive BH. The seven BHs have masses ranging between 0.75 × 10^7 and 6.5 × 10^7 M_⊙, with the mass errors dominated by the uncertainty of the Hubble constant. We compare the megamaser BH mass determination with BH mass measured from the virial estimation method. The virial estimation BH mass in four galaxies is consistent with the megamaser BH mass, but the virial mass uncertainty is much greater. Circumnuclear megamaser disks allow the best mass determination of the central BH mass in external galaxies and significantly improve the observational basis at the low-mass end of the M-σ_⋆ relation. The M-σ_⋆ relation may not be a single, low-scatter power law as originally proposed. MCP observations continue and we expect to obtain more maser BH masses in the future.

The Megamaser Cosmology Project: IV. A Direct Measurement of the Hubble Constant from UGC 3789

In Papers I and II from the Megamaser Cosmology Project, we reported initial observations of H2O masers in an accretion disk of a supermassive black hole at the center of the galaxy UGC 3789, which gave an angular-diameter distance to the galaxy and an estimate of H 0 with 16% uncertainty. We have since conducted more very long baseline interferometric observations of the spatial-velocity structure of these H2O masers, as well as continued monitoring of its spectrum to better measure maser accelerations. These more extensive observations, combined with improved modeling of the masers in the accretion disk of the central supermassive black hole, confirm our previous results, but with significantly improved accuracy. We find H 0 = 68.9 ± 7.1 km s–1 Mpc–1; this estimate of H 0 is independent of other methods and is accurate to ±10%, including sources of systematic error. This places UGC 3789 at an angular-diameter distance of 49.6 ± 5.1 Mpc, with a central supermassive black hole of (1.16 ± 0.12) × 107 M ☉.

The Megamaser Cosmology Project. VI. Observations of NGC 6323

We present observations of the H2O megamasers in the accretion disk of NGC 6323. By combining interferometric and spectral monitoring data, we estimate H

THE MEGAMASER COSMOLOGY PROJECT. VIII. A GEOMETRIC DISTANCE TO NGC 5765b

_{0} = 73^{+26}_{-22}

The Megamaser Cosmology Project.IX. Black hole masses for three maser galaxies

km/s/Mpc, where the low strength of the systemic masers (<15 mJy) limits the accuracy of this estimate. The methods developed here for dealing with weak maser emission provide guidance for observations of similar sources, until significant increases in radio telescope sensitivity, such as anticipated from the next generation Very Large Array, are realized.

The 2014 ALMA Long Baseline Campaign : Observations of Asteroid 3 Juno at 60 Kilometer Resolution

As part of the Megamaser Cosmology Project (MCP), here we present a new geometric distance measurement to the megamaser galaxy NGC 5765b. Through a series of VLBI observations, we have confirmed the water masers trace a thin, sub-parsec Keplerian disk around the nucleus, implying an enclosed mass of 4.55

The ALMA Phasing System: A Beamforming Capability for Ultra-high-resolution Science at (Sub)Millimeter Wavelengths

\pm

The Megamaser Cosmology Project. X. High-resolution Maps and Mass Constraints for SMBHs

0.40

Molecular line emission in NGC 4945, imaged with ALMA

\times~10^{7}M_\odot