I will discuss milliarcsecond imaging of neutron stars and accreting black holes.  The exquisite sensitivity and angular resolution of the Next Generation Very Large Array will allow precise estimates of the proper motions, and often, the geometric parallaxes of these systems.  Astrometry of stellar mass compact objects will provide vital information on natal kicks, and in some cases, system masses through astrometric wobble, yielding one of the few available clues about the nature of the central engines of supernovae.  For supermassive black holes, proper motions in combination with LISA standard siren distances will allow 6D mapping of the phase space of galaxy clusters, providing unique information about the distribution of dark matter within them.  Moving beyond imaging, the ngVLA's capability to use subarrays to make simultaneous measurements at many frequencies will open up the technique of eclipse mapping of X-ray binary jets, allowing a new probe of their structures and acceleration processes.

The ASPECS survey is a sensitive, relatively large cosmic volume search for molecular gas across cosmic time. I will present the design of the survey, then summarize the primary results. We obtain the deepest mm-continuum image of the sky to date, and we make an unbiased determination of the dense gas history of the Universe out to z ~ 4.

With its high sensitivity, excellent angular resolution, and wide spectral coverage, ALMA is revolutionizing our view of galaxies in the nearby universe. I will describe our work on the link between dense gas and star formation for a sample of 9 nearby galaxies from the ALMA archive, which includes measuring the resolved star formation law at high gas surface densities and identifying a new molecular line that appears to be an excellent tracer of the densest star forming gas.

Normally, when astronomers see beautiful, “3D” movies of the Milky Way or the stars and clouds within it, they assume those movies to be cartoons or computer simulations. In this talk, I will describe revolutionary data sets and data-science techniques that are enabling REAL 3D movies of the Milky Way to be made—right now. In particular, I will focus on how so-called “3D dust mapping” has gotten a tremendous distance resolution boost from Gaia, and how interweaving velocity information from spectral-line data cubes, dust maps and 3D stellar velocities reveals never-before-seen views of the solar neighborhood of the Milky Way. The recent discovery Radcliffe Wave, which redefines our understanding of Milky Way’s Local Arm (http://tinyurl.com/radwave), is just the first in a series of revelations to come from this knitting project.

Recent, remarkable images, made by the EHT collaboration of M 87, exhibit a ring of emission, presumably orbiting a six billion solar mass black hole. It is proposed that what is observed is an extensive ergomagnetosphere that connects mechanically to a much larger ejection disk through a magnetic clutch. The ejection disk is envisaged to be powered primarily by the spinning hole and not the infalling gas, which is expelled as a jet-confining, hydromagnetic wind. Implications for general active galactic nuclei, other sources of relativistic jets and future observations will be briefly discussed.

ALMA has revealed that planet-forming disks host a rich chemistry, with molecules displaying complex radial and vertical emission profiles. I review some of the chemical disk structures discovered so far, what they have taught us about the ongoing chemical evolution during planet-formation, and the distribution of volatiles in disks. I also discuss what additional observations are needed to further link disk chemistry to the compositions of nascent planets.

The satellites of the Solar System's giant planets are one of the current frontiers of planetary science, and will be the targets of multiple spacecraft missions in the coming decades. Observations of these objects with ALMA have provided maps of the atmospheres and subsurfaces of these worlds in unprecedented detail, complementing optical/infrared maps of surface composition at a similar resolution. This talk discusses recent ALMA results on Solar System satellites and what we've learned from them about these objects' surface environments, and discusses prospects for discovery with future facilities

Giant star clusters were an important evolutionary element of the early universe, and they appear to be qualitatively different from smaller star clusters such as those currently forming in the Milky Way. Theory suggests that massive stars are crucial to their formation and long-term survival. Stellar winds, paradoxically, may be the key to the inhibition of gas dispersal and feedback that allows the growth of the cluster. I discuss how observations of extragalactic super star clusters with the VLA and ALMA are helping us understand how these clusters form and grow.

Over the past few years, we have found that small-scale "substructures" -- emission deviations on ~few-AU scales -- are prevalent in protoplanetary disks. We expect that these play fundamental roles in the evolution of disk material, and may even trace ongoing planet formation. Prof. Andrews reviews what we've learned so far, primarily from observations with ALMA, discuss the current limitations, and look forward to new opportunities for continued progress in quantifying and explaining the origins of these substructures.

Over the past decade comprehensive and systematic studies of star formation and the gas contents of galaxies during the epochs that are associated with the peak (z~1-3), and subsequent winding down of star formation have enabled us to illustrate the important role that cold gas plays in the assembly of galaxies across cosmic time. These studies show that star forming galaxies contained significantly more molecular gas at earlier cosmic epochs than at the present time. Global rates of galaxy gas accretion, which vary with cosmological expansion, primarily drive this increase in cold gas and star formation rates in the dominant main sequence galaxy population. Studies also show that the molecular gas depletion time depends mainly on redshift or Hubble time, and at a given z, on the vertical location of a galaxy relative to the “star formation main sequence”. In this talk, I will discuss various strategies and methods used to determine the evolution of cold gas contents, and discuss the latest gas scaling relations with redshift, star formation and stellar mass. I will also discuss how simple gas regulator models successfully predict the combined evolution of molecular gas fractions, star formation rates, galactic winds, and gas phase metallicities.

Fast radio bursts (FRBs) were discovered 13 years ago. The advances in the initial phase was the recognition of a large all-sky rate of perhaps of 104 per day followed by the discovery of repeating FRBs or “repeaters” which are either a new class or a subclass. The progress in the last few years has been spectacular. Astronomers have now localized FRBs to their host galaxies at cosmological distances and in some cases to specific locale, such as spiral arms or nuclear region. Just a few months ago, a mega Jansky burst was linked to an active magnetar in our own Galaxy. So at least some FRBs (repeaters) are linked to magnetars. Separately, the use of FRBs for “tomography” of the intergalactic medium (IGM) is now a veritable cottage industry. In talk, I will review the status of this rapidly changing field, speculate on other possible origins of FRBs and end with a forecast for the next five (possibly ten) years.