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High-Mass Star Formation and Mass Flows in the Galaxy and the MUBLO

Adam Ginsburg
Associate Professor [NRAO REU]
Department of Astronomy
University of Florida, Gainesville
  • Postdocs: Miriam Garcia Santa Maria (2024-), Allison Towner (2020-2023)
  • PhD: Desmond Jeff [CV Reber], Theo Richardson, Alyssa Bulatek [GB REU], Nazar Budaiev [GB REU], Savannah Gramze [NRAO REU] , Taehwa Yoo
  • Undergrad: Derod Deal [upcoming NRAO REU], Brice Tingle, Morgan Himes [NRAO REU], Aden Dawson, Brighten Jiang
  • Supported by the NSF: 2008101, 2206511, CAREER 2142300, STSCI grants 1905, 2221
Collaborators: John Bally, Ashley Barnes, Cara Battersby, Roberto Galván-Madrid, Jonathan Henshaw, J. M. Diederik Kruijssen, Steven Longmore, Xing Lu, Fanyi Meng, Elisabeth A.C. Mills, Juergen Ott, Justin Otter [NRAO REU], Álvaro Sánchez-Monge, Peter Schilke, Daniel Walker, Erik Rosolowsky, Eric Koch, Ciriaco Goddi, Brett McGuire, Dick Plambeck, Melvyn Wright, Johan van der Walt, Henrik Beuther, Kei Tanaka, Yichen Zhang, the ALMA-IMF team (Timea Csengeri, Fabien Louvet, Nichol Cunningham, Frederique Motte, Patricio Sanhueza, Thomas Nony, Yohan Pouteau, Melisse Bonfand, Fernando Olguin, Sylvain Bontemps, and many others), and the ACES team
Slides available at https://keflavich.github.io/talks/colloquium_May2024_Socorro.html or from my webpage →talks

A visual tour of the Galaxy

Gaia star colors via ESA

A visual tour of the Galaxy

2MASS via IPAC

A visual tour of the Galaxy

Planck + HI4PI via lambda.gsfc.nasa.gov

A visual tour of the Galaxy

HI: "Diffuse" gas
HI4PI

A visual tour of the Galaxy

Dust
Planck

A visual tour of the Galaxy

CO: molecular gas
Planck

A visual tour of the Galaxy

Star formation drives the evolution of the universe

NASA/WMAP

Star Formation oversimplified

Ṁ
The star formation rate, i.e., how much gas turns to stars
L / M
The light per unit mass, i.e., how stars and stellar populations turn matter into light

High-mass stars produce photons & heavy elements
low-mass stars live practically forever

Point color shows effective temperature, point size shows luminosity (left) and mass (right)
Ekström+ 2012 models, vendian.org colors, www.tinyurl.com/HR-figure

The stellar initial mass function (IMF)

Stars are sampled from this distribution
https://tinyurl.com/IMF-figure
https://tinyurl.com/IMF-figure

Almost all of the light in star-forming galaxies is produced by high-mass stars

NASA/GALEX via wikipedia

The stars form in and from gas (as traced by dust)

Herschel

Most of what we know of star formation in detail comes from small local clouds

Herschel/Palmeirim+ 2013

Most of what we know of star formation in detail comes from small local clouds

ESO/DSS2, De Martin

Cartoon of isolated low-mass star formation

original cartoon by Cormac Purcell, modified by AG

A molecular cloud fragments

The core forms a central protostar

The protostar heats its parent core and forms a disk

It drives an outflow and consumes (or runs from or blows out) its core

Eventually, you end with just a star-disk system

Cartoon of isolated low-mass star formation

original cartoon by Cormac Purcell, modified by AG

The isolated cartoon is wrong in several ways

Cores fragment. Massive stars cook their neighbors in hot cores.

Most of what we know of star formation in detail comes from small local clouds

ESO/DSS2, De Martin
Briceño+ 2002
They contain only low-mass stars and do not represent star formation in general

Most stars form in denser regions

HST
NGC 3603 is a high-mass (104 M⊙) cluster
Lada & Lada 2003:
5-10% in bound clusters
in our Galaxy

SSCs are common in starburst nuclei and drive galactic outflows

NGC 253 protoclusters (Leroy+2018)
NGC 4945 protoclusters (Emig+2020)

Star formation drives the evolution of the universe

Most stars in most galaxies formed long ago
Madau 2014

Galaxies were smaller & denser back then

Conselice 2014
STSCI; Pappovich, Ferguson, Faber, Labbe

Proto-cluster regions in our Galaxy sample conditions that were commonplace in the early universe

Mowla+ 2022
Two ALMA large programs probe these conditions:
ALMA-IMF:
  • 15 High-mass protoclusters probing young (few stars) to old (blowing out gas)
  • Two ALMA bands looking at cold gas & dust
  • Data published, analysis ongoing
ACES:
  • The whole Galactic Center, with low-SF and high-SF clouds
  • One ALMA band, biggest mosaic made.
  • Data all delivered, mostly reduced

Big Questions in Star Formation

I'll highlight incremental progress toward answering some of these

  • How does the IMF vary, and what controls its variation?
  • What controls the star formation rate in galaxies?
  • When and how do planets form?
  • How does stellar clustering affect each of these?

To answer these questions,
we observe the gas & dust where stars form

To answer these questions,
we observe the gas & dust where stars form

To answer these questions,
we observe the gas & dust where stars form: Orion

To answer these questions,
we observe the gas & dust where stars form: Orion

To answer these questions,
we observe the gas & dust where stars form: Orion

Kong+ 2021, 2019, 2018

To answer these questions,
we observe the gas & dust where stars form: Orion

The Integral-Shaped filament has $\sim10^4$ M$_\odot$ of gas over $\sim$10 pc

To answer these questions,
we observe the gas & dust where stars form: Orion

Bally+ 2015, 2017
The Orion Molecular Cloud is the closest (d$\sim400$ pc) site of high-mass star formation

To answer these questions,
we observe the gas & dust where stars form: Orion

Bally+ 2015, 2017
BOOM!

Orion Source I
a disk around a 15 M⊙ YSO

Salt: NaCl
Image: Ginsburg, NRAO

Temperature?

Temperature?

A contrived model

Observing the Keplerian rotation profile of a disk is the most direct way to measure a protostar's mass

(we can only see the disk, not the star itself)

Salt is a tool to weigh HMYSOs

Keplerian orbits measure mass

More Brinary disks

Ginsburg+ 2023: New sample. Miriam Garcia Santa-Maria is following up

Briny chemistry:

Salts, SiS, SiO, and PN are seen together [but limited spectral coverage]

The Orion Molecular Cloud Core is a dense cluster


Otter+ 2021, Ballering+ 2023, Wright+ 2020, 2022 2023
FOV: 0.07 pc (16000 AU)

Likely the only gas-rich protocluster with a complete YSO census:
ALMA (Otter), VLA (Ballering, Wright), Chandra, JWST....

N*OMC(Otter+ 2021) = 1.6 x 105 pc-3
N*ONC(Otter+ 2021) = 0.6 x 105 pc-3
N*ONC(Hillenbrand+ 1998) = 0.2 x 105 pc-3

Most stars form in denser regions

Spitzer, Gutermuth
NGC 1333, an embedded low-mass cluster
Lada & Lada 2003: >70% in embedded clusters
500 years ago, four or more stars were in a multiple system
The old picture involved source n, but it's not moving fast enough

Clusters are sites of interactions & collisions

Bally+ 2017, 2020
Farias+ 2018

The BN/I/x interaction is the poster case of accretion ended by dynamical interaction.
Goddi+ 2020

Interactions throughout formation


The outflow (& disk) around W51 North changed direction by ~50 deg in < 100 years.

0.25-0.5 M⊙ accreted

We don't know the frequency of these events; they are likely bright transients, but most often heavily dust-obscured


The Inner Galaxy is where most stars form


The Inner Galaxy is where most stars form

ALMA-IMF maps 15 high-mass star-forming regions

Orange layer shows ATLASGAL 870$\mu$m dust:
the dense gas where stars form

ALMA-IMF maps 15 high-mass star-forming regions

Orange layer shows ATLASGAL 870$\mu$m dust:
the dense gas where stars form ALMA-IMF targets are among the most massive between 2-6 kpc from the sun
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]
1mm Dust
[ALMA]
870 μm Dust
[APEX/ATLASGAL]

ALMA-IMF data highlights

Gas flows in N2H+ filaments (Álvarez-Gutiérrez+ 2024)
Collapse is slower on larger scales, but fast enough to matter.

ALMA-IMF: Continuum Data → core catalogs

www.almaimf.com/data.html
Pouteau+ 2022 W43-MM2/3

ALMA-IMF: CMF measurement & YSO counting

www.almaimf.com
(these papers are all now submitted or accepted, but this is a screenshot that includes everyone's photos...)

Classic model: a "core mass function" maps to the IMF

Alves+ 2007

Many alternatives, no consensus on which is best

Offner+ 2014
However, a core is not a core.
≠
Cores change states
Offner+ 2022

...but the naïve version doesn't work

Offner+ 2014

ALMA-IMF "Core" Mass CDF

The CMF in protoclusters is shallower than the IMF
but this result is and will remain controversial because of small numbers & questions of how to go from flux to mass
Louvet+ 2024

ALMA-IMF "Core" Mass CDF

The CMF in "quiescent" outer regions is (marginally) steeper than the "active" central regions
Louvet+ 2024
The path to better mass measurement:
YSO modeling → luminosity functions
Richardson, Ginsburg, Indebetouw, Robitaille 2024 (2401.12810)
NSF 2008101:
"How are stellar masses set?"
Theo Richardson
The path to better mass measurement:
YSO modeling → luminosity functions
NSF 2008101: "How are stellar masses set?"
Theo Richardson

Is star formation different in other environments?
In the Galactic Center?

Is star formation different in other environments?
In the Galactic Center?

Is star formation different in other environments?
In the Galactic Center?

Is star formation different in other environments?
In the Galactic Center?

Is star formation different in other environments?
In the Galactic Center?

The CMZ

$\sim10^8$ M$_\odot$ of gas in $\sim200$ pc, 10% of Galactic star formation
Image: NRAO, Ginsburg
Ginsburg+ 2018a

The Central Molecular Zone of the Galaxy represents one extreme of star forming conditions in the Galaxy

PPVII review: Henshaw, Barnes, Battersby, Ginsburg, Sormani, Walker
Mass accretion onto the CMZ: "Extreme Velocity Features"
Savannah Gramze

Velocity bridge: evidence for collision after overshooting Gramze+ 2023

How does gas flow into the Galactic Center?

We think the ring-like feature formed in this simulation is a good model for the CMZ
Sormani+ in prep

The CMZ

www.adamgginsburg.com/ACES_tour.html
Image: NRAO, Ginsburg
Ginsburg+ 2018a

The CMZ: ACES

www.adamgginsburg.com/ACES_tour.html
Image: NRAO, Ginsburg
Ginsburg+ 2018a

The CMZ: ACES

www.adamgginsburg.com/ACES_tour.html

ACES: the ALMA survey of the CMZ

A brief summary & progress report

  • 3mm, 1.5", whole CMZ
  • High spectral resolution (0.2 km/s) in HCO+ and HNCO
  • Data products on their way! 100% observed, ~75% delivered
  • Several pilot programs demonstrating expected results
The CMZ at 3mm Ginsburg+ 2020
To be observed Feb 2023, "TENS"
(GBT A-rank)
The CMZ at 3mm Ginsburg+ 2020
The CMZ at 3mm Pound & Yusef-Zadeh 2018
The CMZ at 3mm Pound & Yusef-Zadeh 2018
The CMZ at 3mm ACES team, in prep
The CMZ at 3mm ACES team, in prep

The proto-Super Star Cluster Sgr B2 is forming in the CMZ

Image: NRAO, Ginsburg
Ginsburg+ 2018a
 Two $>10^4$ M$_\odot$ clusters within $<3$ pc; $10^6$ M$_\odot$ of gas in $\sim10$ pc

In denser (parts of) galaxies, more stars form in clusters

Kruijssen 2012
Ginsburg & Kruijssen 2018
Γ is the fraction of stars forming in bound clusters
Galaxy averages

The "Bound Cluster Fraction" is predicted higher in the CMZ

Kruijssen 2012
Ginsburg & Kruijssen 2018
Γ is the fraction of stars forming in bound clusters
Galaxy averages
CMZ prediction

The "Bound Cluster Fraction" is higher in CMZs

Kruijssen 2012
Ginsburg & Kruijssen 2018
Γ is the fraction of stars forming in bound clusters
Galaxy averages
CMZ prediction
Sgr B2 data

The "Bound Cluster Fraction" was higher in the past

Pfeffer+ 2018

The proto-Super Star Cluster Sgr B2 is forming in the CMZ

Image: NRAO, Ginsburg
Ginsburg+ 2018a
 Two $>10^4$ M$_\odot$ clusters within $<3$ pc; $10^6$ M$_\odot$ of gas in $\sim10$ pc

The proto-Super Star Cluster Sgr B2 is forming in the CMZ

Image: NRAO, Ginsburg
Ginsburg+ 2018a
 Two $>10^4$ M$_\odot$ clusters within $<3$ pc; $10^6$ M$_\odot$ of gas in $\sim10$ pc

Comparison of Sgr B2 (one cloud, 200 pc2) with
ALMA-IMF (15 SFRs, 53 pc2)

3mm catalog → Simplistic mass inferences

Ginsburg+ 2018a
At this sensitivity, all are M>8⊙ YSOs
Mtot = 8 M⊙
∫0∞ M N(M) dM
∫8∞ M N(M) dM
= 96 M ⊙

Zoom in to Sgr B2

Some cores fragment, some disappear

At higher resolution, some cores contain clusters, some are starless. Budaiev+ 2024

Some cores fragment, some disappear

At higher resolution, some cores contain clusters, some are starless. Budaiev+ 2024

Some cores fragment, some disappear

At higher resolution, some cores contain clusters, some are starless. Budaiev+ 2024

Some cores fragment, some disappear

At higher resolution, some cores contain clusters, some are starless. Budaiev+ 2024

Some cores fragment, some disappear

At higher resolution, some cores contain clusters, some are starless. Budaiev+ 2024

What's next?


Nazar has cataloged 100s of new masers in Sgr B2 (VLA 18A-229)
A quick look at what's coming: Nazar has cataloged 100s of new masers in Sgr B2 (VLA 18A-229)

Some cores fragment, some disappear

Taehwa Yoo is measuring fragmentation
toward W51

What's inside the cores?

What's inside the cores?

What's inside the cores?

Some cores fragment, some disappear

Taehwa Yoo is measuring fragmentation
toward W51

Trend: More massive cores fragment more.



Yoo+ in prep: W51
Budaiev+ 2024: Sgr B2

Ammonia Masers:

Derod Deal
VLA 19A-154

Several different scenarios: mix of mechanisms

Offner+ 2014

Orion → Galactic Disk → CMZ


More massive stars,
more massive cores,
more stars in clusters

Final segment:

Astrochemistry:
Hot Cores
Ices
Line Surveys

Hot cores in the Galactic center: Distributed MYSOs

Desmond Jeff+ 2024

Ten hot cores in Sgr B2 DS
outside the massive clusters
TG ~ 200-500 K
M ~ 200 - 2900 M⊙
(proto-O-stars / clusters)
~5% of cores are hot cores
Sgr B2 DS: More massive cores than the Disk
Desmond Jeff+ 2024

Hot Cores

Hot cores are chemically rich sites of high-mass star formation.
They are only found in the more distant disk & CMZ regions
Ginsburg+ 2017

Hot Cores

Hot cores are chemically rich sites of high-mass star formation.
They are only found in the more distant disk & CMZ regions
Ginsburg+ 2017
The Brick isn't forming many stars
Ginsburg+ 2023
https://cosmicds.github.io/minids/jwst-brick/
The Brick is icy
Ginsburg+ 2023
https://cosmicds.github.io/minids/jwst-brick/
The Brick is icy
Ginsburg+ 2023
https://cosmicds.github.io/minids/jwst-brick/
Building new tools: Spectral Line Survey of The Brick
Alyssa Bulatek+ 2023
Alyssa Bulatek: Spectral Line Survey of The Brick
  • Dasar line at 107 GHz
  • CH3OH only in absorption
  • Occurs at density $n<10^6 \mathrm{cm}^{-3}$

Summary

Dynamical interactions are common where stars form
and they are more common in clusters. Environment matters!

Most stars form in regions unlike the solar neighborhood
  • Shallower Core Mass Function in richer SF regions
  • The Galactic Center forms more stars in clusters


We have, and are building more, tools to measure masses
  • ALMA-IMF core catalogs with high-resolution followup & modeling
  • Hot cores track the earliest stage of HMSF
  • Salt is a new tool to probe disks around high-mass stars


The MUBLO
Broad-Line
Broad-Line (broader than the CMZ)
Weird chemistry (no SiO?!?)
Dusty
...and cold, using SO LTE model
No NIR counterpart
No counterparts!
Hypotheses & Data

Some notes on Data Scale

ALMA-IMF
250 TB
ACES
300 TB
Sgr B2: VLA 18A-229, 22A-020, ALMA 2013.1.00269.S, 2016.1.00550.S, 2017.1.00114.S
150 TB

Reducing and analyzing these data is impractical without huge allocations on parallel, scalable systems
JWST Bonus Slides
JWST Bonus Slides
JWST Bonus Slides
JWST Bonus Slides
JWST Bonus Slides

Brinary disks

The SrcI disk has gas-phase salt (NaCl, KCl) and water (H2O).
So it's brine.
(blame Adam Leroy for this term)
IRAS16547A/B (Tanaka+ 2020) have (unresolved) salt water disks

More Brinary disks

Ginsburg+ 2023: New sample

Brine lines measure dynamical mass


NaCl v=1 J=18-17 Stack of v=[0,1] Ju=[18,17]
SrcI

15 M⊙ 30 M⊙ 40 M⊙

What have we learned about brinaries?

  • Neither common nor rare: 10 known so far, >23 HMYSO candidates examined
    • Y: SrcI, G17, IRAS16547, NGC6334I, G351.77, W33A
      • Ginsburg+ 2019, Tanaka+ 2020, Ginsburg+ 2022
    • N: I16523, I18089, G11, G5, NGC6334IN, S255IR NIRS3, G333.23-0.06, I18162
      • Ginsburg+ 2022
  • Coincide w/line-poor sources
    • Not hot cores; little mass reservoir?
  • Trace reasonably symmetric disks (in the well-resolved cases)
    • there is some ambiguity b/w disk & outflow in one case

Compare: G17 vs G11

G17: Brinary
Hot (ionizing) photosphere. Circular disk.
G11: Not-Brinary
Molecule rich, kinematically messy & extended

W51 e2e: Too optically thick at 1mm to measure disk

Goddi+ 2020

CS v=0 J=1-0 and v=0 J=2-1 masers may trace the disk?

Ginsburg+ 2019
M = 24-10+12M⊙
if the masers trace a disk

CS maser conditions

van der Walt+ 2020
  • Top: CS J=1-0, Bottom: CS J=2-1
  • Red: Consistent w/W51e2e observations
  • Masers do not coexist; require different specific CS column
    (N2-1=1015.6, N1-01016.1 cm-2)
  • Require high abundance (XCS > 10-5)
  • Hot (300-500 K), moderate-density (n~105 cm-3): Disk surface? Or outflow cavity wall?
blank
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Salt backup slides

Possible future uses for these lines?

  • Metallicity measurement in deeply embedded star-forming environments? (at least of Na, K, Cl)
  • Disk kinematics of high-mass stars, which are otherwise unobservable (τ>1 at mm wavelengths)
  • Disk kinematic measurements at early stages?
  • Probe dust destruction (and/or formation?) in outflows, disks?
  • Probe radiation environment around HMYSOs?

Why do we see salt?

  • Previously, NaCl & KCl only in AGB* atmospheres,
    associated with dust formation
  • Most likely dust destruction here
    Dust destruction happens immediately as the outflow is launched?
  • What about excitation? We see vibrationally excited lines, which are not seen in AGB*s

We do not have a viable model to explain these temperatures

A strong non-blackbody radiation field from 25-40 µm may explain them.
Forsterite (MgSiO4) has some emission bands in that range. Maybe?
What's next for salts? (VLA 22A-022, 23A-016)
Deep VLA observations of low-J lines in Orion

How is star formation in high-mass clusters different?

Cartoon of high- and low-mass star formation

Main difference: massive stars affect their surroundings
original cartoon by Cormac Purcell, modified by AG

Classic HII region feedback:
O-stars clear out their environment
HST
McLeod, Dale, Ginsburg et al 2015

Accreting massive young stars affect their environment

Ginsburg+ 2017

Accreting massive young stars affect their environment

Ginsburg+ 2017

Accreting massive young stars affect their environment

Ginsburg+ 2017
Ginsburg+ 2017
Ginsburg+ 2017

The characteristic fragmentation scale


The Jeans Mass MJ is the mass where gravity and thermal pressure are balanced.

MJ ∝ T3/2 ρ−1/2

The characteristic fragmentation scale is larger

Jeans Mass MJ ∝ T3/2 ρ−1/2
Ginsburg+ 2017

Feedback affects 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

The cartoon in the context of HMSF

original cartoon by Cormac Purcell, modified by AG
These high mass cores suppress low-mass star formation (LMSF) in their vicinity. They reduce or prevent LMSF in the cores of stellar clusters.

More extreme: 'cooperative accretion'

original cartoon by Cormac Purcell, modified by AG
With enough high-mass stars forming concurrently, massive stars may prevent fragmentation entirely.
If they still have enough gravity to bind the gas, the remaining gas is forced onto the most massive gravitational sinks.
Zinnecker & Yorke 2007, Ginsburg+ 2017

Large scales again:
What governs the star formation rate?

Kennicutt & Evans 2012

Turbulent ISM models

Turbulent ISM models

Turbulent ISM models

Measuring Line Profiles

SCOUSE uses pyspeckit for manual fits. Gausspy+ is machine-learning trained. We're exploring more automated approaches.

ALMA enables protostar counting in
distant, massive clouds

Sgr B2: the most massive & star-forming cloud in the Galaxy
Ginsburg+ 2018a

How do we learn about clustering? The IMF?

  • Count objects:
    • Cores are (sometimes) countable
    • Protostars are countable

YSO counts let us investigate thresholds

Local cloud studies support the idea of a gas density threshold for star formation

Lada+ 2010
Thresholds are used in simulations to say
"if gas reaches this density, turn it into stars"
Ginsburg+ 2018a
Compare YSO counts in Sgr B2 and the CMC
Ginsburg+ 2018a

Is there a threshold?

Ginsburg+ 2018a

Is there a threshold?

Ginsburg+ 2018a

A threshold separates Sgr B2 from The Brick

Ginsburg+ 2018a
Desmond Jeff+ 2024
Walker+ 2021

3mm Luminosity Function

Ginsburg+ 2018a

What are the sources?

Ginsburg+ 2018a
At this sensitivity, all are M>8⊙ YSOs

Mass measurements: Optically thin, isothermal dust



TD estimated with PPMAP fits to Herschel data
(~6" resolution)

Simple models assuming TD ~ f(M) don't change CMF much
Pouteau+ 2022

We can do better with YSO models and TG measurements

From YSO counts to the IMF?

How do we measure the CMF if the cores all have YSOs in them?
Mapping accretion histories
(left: IS, right: TC)
onto the Robitaille 2017 model grid

Key addition:
Envelope mass!
SPICY-ALMA-IMF:
Richardson-enhanced Robitaille+ 2017 model grid fits including ALMA data
UG team:
Sydney Petz

Brice Tingle

Morgan Himes

Our Galaxy's center, the CMZ, has denser gas than the Galactic average

Image: NRAO, Ginsburg
Mills, Ginsburg+ 2018; Kruijssen & Longmore 2013
Cold Dust
Hot, ionized gas
Hot dust/PAHs

ALMA-IMF:
The CMF is shallow (top-heavy) in HMSFRs

Pouteau+ 2022 W43-MM2/3 CMF
Motte+ 2018 W43-MM1 CMF: α≳-1

Top-heavier IMFs are seen in high-mass clusters,
CMFs in protoclusters

Hosek+ 2018
https://tinyurl.com/IMF-figure

ALMA-IMF:
The CMF is shallow, and steepens with time?

Louvet+, subm
ALMA-IMF Line Data: 320 cataloged SiO Outflows
Allison Towner
Resolved, structured SiO outflows
5-60% of SiO at low-velocities:
Relic outflows?
ALMA-IMF Line Data: CH3CN, CH3CCH
Temperature measurements with per-pixel rotation diagrams
Jeff+ in prep (CH3OH in CMZ), Wyrowski+ in prep (CH3CN in ALMA-IMF)
Hot cores in ALMA-IMF: From rare objects to a population
Cores with line forests
TD>50 K
TG ≳100K
Brouillet+ 2022

Hot core overview:

  • 9 HCs in W43-MM1 (Brouillet+ 2022)
  • ~60-70 HCs in ALMA-IMF sample from CH3OCHO (Bonfand+ 2024; left)
  • ~10% of continuum cores are within hot cores
  • CH3CN temperature maps (Wyrowski+ in prep)

ALMA-IMF Key Results summary

  • Rich, science-ready data (Ginsburg+ 2022, Cunningham+ 2023)
  • CMF is top-heavy in HMSFRs (Pouteau+ 2022, Louvet+ 2024)
  • Core fragmentation is not 1-to-1 [WIP] (Budaiev+ (CMZ), Yoo+ (W51), Louvet+ (W43), ...)
  • 10% of $M\gtrsim1\mathrm{~M}_\odot$ cores are hot cores (Brouillet+ 2022, Bonfand+ 2024, Wyrowski+)
  • Outflow feedback builds over time, sets initial conditions for many cores (Nony+ 2022, Towner+ 2023)