Surveys of the dense Galactic ISM with ALMA, VLA, GBT, and SMA

Highlights & Outlook

Adam Ginsburg

With students: Desmond Jeff (UF PhD), Theo Richardson (UF PhD), Connor McClellan (NRAO REU 2018, now UVA), Josh Machado (NRAO REU 2019, now Ohio State), Danielle Bovie (UF REU 2020), Madeline Hall (UF undergrad), and many collaborators
Slides available at
https://keflavich.github.io/talks/aas236_observations_of_the_ISM.html
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Good and bad observables

In the ISM:
  • Mass is not observable
  • Age is not observable
  • Line-of-sight velocity is generally observable
  • Gas temperature is sometimes kinda observable

Theorists: Don't compare theoretical mass & age to reported, instead model observables
Observers: We need to emphasize systematic errors appropriately

ALMA, VLA, GBT, SMA observations of Galactic HMSFRs

A few key surveys are ongoing or done:

Kinematics

ALMA & VLA surveys will provide detailed kinematics of the dense gas: N2H+, HC3N, NH3 etc.
Henshaw+2020: Velocity 'wiggles' pervade the ISM on all scales.
SCOUSE and other tools will make these measurements more common.

Kinematics: New tools, new measurements

Semi-automated
Automated - heuristic-based
Automated – convolutional neural network
Automated – Bayesian Monte Carlo
Slide credit: Brian Svoboda

Kinematics and Temperature

HMSFRs are warmer, broader-lined than local clouds
GAS KEYSTONE VLA
Friesen & Pineda+ 2017 (left); Keown+ 2019 (middle); Machado+ in prep, W51 (right)

Kinematics and Temperature

Narrow-linewidth local cloud analogs exist within HMSFR clouds.
Machado+ in prep, W51

Kinematics and Temperature

HMSFRs are warmer, broader-lined than local clouds
Svoboda+ in prep, Mon R2 (left); Machado+ in prep, W51 (right)

Kinematics and Temperature

HMSFRs are warmer, broader-lined than local clouds
Svoboda+ in prep, Mon R2 (left); Machado+ in prep, W51 (right)

Kinematics and Temperature

HMSFRs are warmer, broader-lined than local clouds
GAS KEYSTONE VLA
Friesen & Pineda+ 2017 (left); Keown+ 2019 (middle); Machado+ in prep, W51 (right)

ALMA-IMF has many dense thermometers

Temperature traces feedback in the densest gas and sets fragmentation scales

UF graduate student Desmond Jeff is extending this project

Feedback affects large volumes of dense gas

ALMA + VLA + GBT together give multiple temperature probes on multiple scales.
High-mass protoclusters are filled with gas warmed by feedback.
Ginsburg+ 2017, Machado+ in prep

Connecting the ISM to SF outcomes

Sgr B2: Ginsburg+ 2018a "The Brick": Henshaw+ 2019a
Ginsburg+ 2018a
Ginsburg+ 2018a
UF PhD student Theo Richardson is improving protostellar modeling using the Robitaille+ 2017 models
Ginsburg+ 2018a

A threshold separates Sgr B2 from The Brick

Ginsburg+ 2018a

A threshold separates Sgr B2 from The Brick

Ginsburg+ 2018a

CMZoom: Star-forming clouds are more concentrated

Battersby+ submitted

ALMA, VLA, GBT, SMA observations of Galactic HMSFRs

ALMA-IMF: N2H+, others

N2H+ structures are clumpy, wispy, and filamentary.
Louvet+ in prep will provide a sample of hundreds of continuum cores

CMZoom: SMA 1mm survey

Battersby+ submitted
Hatchfield+ in prep

The MUSTANG Galactic Plane Survey (MGPS90)

90 GHz, 9" Galactic Plane Survey;
Ginsburg+ 2020 gives first results

Summary

  • Gas temperature & LOS velocity can be accurately measured, mass can be inaccurately (but still usefully) measured
  • Feedback affects large volumes of dense gas, not just single cores
  • ALMA, VLA, GBT, SMA surveys are delivering parsec-scale, 1000-AU resolution maps of velocity, temperature, kinda density, and star formation
  • Cloud comparison studies allow tests of physical models, and they are becoming possible
Slides available at https://keflavich.github.io/talks/aas236_observations_of_the_ISM.html.

Take mass measurements with a grain of salt

  • Star masses are measurable via disk Keplerian curves.
  • Orion's Source I has a central 15 M⊙ star.
Ginsburg+ 2018c
Ginsburg+ 2019b