1. Shaping the ngVLA: Science Advisory Council and Working Groups
Alberto D. Bolatto on behalf of SAC
co-Chair ngVLA SAC
University of Maryland

2. Outline Structure and role of the SAC Process for shaping the ngVLA
Recommendations so far
Next steps

3. Science Advisory Council
The SAC was formed by recommendation of the NRAO-UC
Its task is to provide science direction
By construction it represents the external community
Currently 22 members + ex officio
Mostly US institutions: 5 international members (Canada, Mexico, Japan, Germany)
Representation of US community with a wide scientific and geographic footprint

4. Science Advisory Council
For practical reasons, the SAC is split in Science Working Groups
Working Groups reflect broad science areas:
Cradle of Life (everything on sub-GMC scales including the Solar System)
Galactic Ecosystems (from the Milky Way to nearby galaxies)
Galaxy Assembly (the high-redshift universe)
Fundamental Physics (time domain, Cosmology, Physics)
SWGs are open: members of the community who are not in the SAC can participate in the SWGs
For example, creating Science Use cases
Or participating in this meeting!
Coordination is provided by an Executive Committee

5. Shaping the ngVLA
Since last November we have embarked on a process to shape the ngVLA
The basis was provided by the White Papers from 2015
Each Working Group solicited Science Use Cases from the community
Each Science Use Case is the brief description and setup for an experiment (e.g., ``Imaging Structure and the Spatially Resolved Spectral Slope in Debris Disks’’)
Goals, Rationale, Measurements, Uniqueness, Longevity and tables summarizing required frequencies, sensitivities, resolution, etc
Open experimental setup to make process science-driven
Collected over 70 Use Cases!
There is still time for additional community input!

6. Shaping the ngVLA
The Science Use Cases underwent assessment by the SAC
Two mechanisms used:
Discussion in telecons inside the SWGs
Online assessment questionnaires with 13 questions
Working Group Chairs brought forward the most compelling science goals
Sometimes those encompass more than one use case
We identified 6 Key Science Goals for the instrument
The document is a draft, to be discussed at the SAC f2f meeting taking place after the end of this conference. Discussions and thoughts during the meeting will be important.
But every Science User Case is part of the optimization!

7. Shaping the ngVLA In parallel:
SAC – TAC interactions (working lunch yesterday)
Community studies solicited and funded by NRAO
Intended to address technical aspects of the ngVLA design
We will see some results during these days
Their information will be incorporated into the SAC / TAC discussions
Major design optimization effort undertaken by NRAO (Selina talk)
Parametric cost model developed
Science use cases broken up into ~180 subcases and used as inputs: this is a science- driven optimization
Your input is important! This is your instrument!

8. Key Science Goals under Evaluation
Characterizing the Terrestrial Planet Forming Region in Nearby Young Solar Analogues
The ngVLA can study planet-disk interaction in the innermost region of the disk, with sensitivity to Jovian and Super-Earth induced perturbations
Because of close-in distances, it can follow the evolution over orbital timescales (see Ricci talk)

9. Key Science Goals under Evaluation
Probing the Initial Conditions for Planetary Systems and Life with Astrochemistry
The ngVLA can detect complex pre-biotic molecules and provide the chemical initial conditions in forming solar systems and individual planets (e.g., probe the water snow line, the cold disk midplane --- see Willacy, McGuire talks)

10. Key Science Goals under Evaluation
The Assembly and Structure of Galaxies Throughout Cosmic History
Order-of-magnitude improvement in depth and area for surveys of cold gas in high-z galaxies
It also enables routine sub-kpc imaging of the structure of protogalactic disks at any redshift where CO exists (see Riechers, Casey, Sharon talks)

11. Key Science Goals under Evaluation
Understanding How Galaxies Produce New Generations of Stars
The ngVLA can study extended atomic reservoirs and large samples of GMC populations
Unique windows into the physical and chemical properties of accretion, transport, phase change, and excretion processes (see Kepley, Nyland talks)
NGC 628: THINGS HI (12”, blue), PHANGS ALMA CO (1”, red), IRAC 4.5 um (green)

12. Key Science Goals under Evaluation
VLA
SKA phase 1
Pulsars in the Galactic Center as Fundamental Tests of Gravity
The ngVLA sensitivity and frequency coverage will probe deeper than possible into the GC area looking for pulsars, which are moving clocks in the space-time potential of Sgr A*
New tests of theories of gravity, constraints on exotic binaries, SF history, stellar dynamics and evolution, and ISM at the GC
Estimates are as high as 1,000 PSRs. Only know example is PSR J magnetar (see Bower talk)
ngVLA

13. Key Science Goals under Evaluation
High Precision Astrometry to Determine the Size of the Galaxy and the Scale of the Universe
Distances are fundamental to astronomy, and astrometry is being reinvigorated by Gaia
The ngVLA can improve dramatically over current VLBA capabilities, from young stars to the distance to Sgr A* to the value of Ho (see Maccarone talk)

14. Next Steps Community engagement
Crucial to get a good pool of Science Use Cases to define best instrument
Design is not closed: it’s just starting
More Community Studies?
Key to spread the word: to be a reality, this instrument has to be supported beyond the radio community
You are the ambassadors.
Speaker Bureau, material for talks
Next ngVLA meeting June 2018
Special session at AAS in January “The VLA Today and Tomorrow”

15. Next Steps Change the name to something more meaningful?
Publication of a Science Book
The 75 Science Use cases provide the basis
Will be sent back to authors for polishing
Not limited to what we have in hand
You have an idea? We want to hear from you!
Proposal to the 2020 Decadal
Detailed design and testing need resources beyond those in hand

16. This is your instrument
To become a reality, the ngVLA needs the support of the entire US community
You are the start. If you are excited about this instrument, please convey your excitement to your colleagues
ALMA has shown that radio interferometers are not just for radio astronomers. Explain to your colleagues what this instrument could do for their science
Cannot say it frequently enough: help us define the best instrument