H I clouds near the Galactic Center: Possible tracers for a - - PowerPoint PPT Presentation

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Jan 14, 2023 262 likes •386 views

The Role of Gas in Galaxy Dynamics October 3 rd , Malta H I clouds near the Galactic Center: Possible tracers for a Milky-Way nuclear wind? Enrico Di Teodoro Enrico Di Teodoro Enrico Di Teodoro Research School of Astronomy and Astrophysics

SLIDE 1

Gas in Galaxies - Malta Gas in Galaxies - Malta

HI clouds near the Galactic Center:

Possible tracers for a Milky-Way nuclear wind?

Enrico Di Teodoro

Research School of Astronomy and Astrophysics Australian National University

Enrico Di Teodoro

Research School of Astronomy and Astrophysics Australian National University

Enrico Di Teodoro

Research School of Astronomy and Astrophysics Australian National University Collaborators: Naomi McClure-Griffiths (RSAA), Felix J. Lockman (NRAO-GBT)

The Role of Gas in Galaxy Dynamics October 3rd, Malta

SLIDE 2

Gas in Galaxies - Malta Gas in Galaxies - Malta

Galactic Wind In The Milky Way Galactic Wind In The Milky Way

Our Galaxy has its own wind!

Giant lobes extending to 8-10 kpc

Ackermann et al., 2014

Bi-conical outflow generated a few 106 years ago by either SF

(Crocker+11) or SMBH (Yang+12)

Fermi Bubbles

McClure-Griffiths+13 found 86 clouds at the GC not following rotation Entrained in a wind at ~200 km/s ATCA HI Data Wind model

SLIDE 3

Gas in Galaxies - Malta Gas in Galaxies - Malta

A new Green Bank Telescope survey A new Green Bank Telescope survey ATCA-GC GASS (HI4PI) GBT

(McClureGriffiths+13) (McClureGriffiths+09) (Di Teodoro+, subm.)

(l,b) region Velocity range (km/s) Spatial resolution (arcmin) Channel width (km/s) Sensitivity (Kelvin) ± 4º ± 250 2.4 1.00 0.700 All sky ± 450 15.9 0.82 0.057 ± 10º ± 650 9.1 0.90 0.025

10 -5 0 5 10

Galactic Longitude (deg) Galactic Latitude (deg)

10 -5 0 5 10

A new survey with 100 m GBT single-dish telescope to widen McClure-Griffiths+13 work High sensitivity

ATCA GBT

SLIDE 4

Gas in Galaxies - Malta Gas in Galaxies - Malta VLSR = 200 km/s

20 -10 0 10 20

Galactic Longitude (degree) Galactic Latitude (degree)

20 -10 0 10 20
20 -10 0 10 20

Galactic Longitude (degree) Galactic Latitude (degree)

20 -10 0 10 20

VLSR = -130 km/s

Masking the MW disk emission Masking the MW disk emission GALACTIC DISK ROTATION GALACTIC DISK ROTATION

ANOMALOUS CLOUDS ANOMALOUS CLOUDS GOAL: detecting and studying anomalous clouds above and below the GC

Clouds not in the disk Masking the MW disk by modelling it!

SLIDE 5

Gas in Galaxies - Malta Gas in Galaxies - Malta

Results: source detection Results: source detection

106 anomalous clouds covering ~ 130 deg2

GC GC

SLIDE 6

Gas in Galaxies - Malta Gas in Galaxies - Malta

Results: property distributions Results: property distributions

|VLSR| < 350 km/s Δv ~ 5 - 30 km/s R < ~ 40 pc NHI ~ 5x1018 - 1020

No correlation between FHWM, R or NHI with latitude (height)

SLIDE 7

Gas in Galaxies - Malta Gas in Galaxies - Malta

Wind kinematic model Wind kinematic model

Describing observed cloud kinematic with a simple a galactic wind model

SUN GC R z θ l b R0 D d r CLOUD ϕ x y

Vw ≡ Vw(r)

Simplest model defined by 2 parameters: - wind velocity Vw = const

opening angle α = π - 2φ

A cloud in (R, z, θ) with V = V(r) can be easily mapped into the (l, b, VLSR) system:

SLIDE 8

Gas in Galaxies - Malta Gas in Galaxies - Malta

Wind best model Wind best model

Simulating winds with different velocities and opening angles

300 km/s < Vw < 400 km/s α > 140º Best model Vw = 330 km/s

SLIDE 9

Gas in Galaxies - Malta Gas in Galaxies - Malta

Derived wind properties Derived wind properties

Model-dependent derived properties for a wind with Vw = 330 km/s and α = 140º

Total HI mass in clouds: 1 x 106 Msun
Wind kinetic power: > 3 x 1039 erg/s

Can be supplied by GC with SFR~0.1-0.2 Ms/yr (Crocker12)

Cloud lifetimes: ~ few x 106 years

Challenge for theory. Destruction timescales are generally lower

Cold mass loading rate: ~ 0.1 Msun/yr

Similar to SFR in the CMZ

Clouds likely represent the cold gas component entrained in a hot, starburst-driven nuclear wind

SLIDE 10

Gas in Galaxies - Malta Gas in Galaxies - Malta

Conclusions Conclusions

A population of anomalous clouds definitely exists at the GC

They can be used to trace the properties of MW wind

Our new GBT survey revealed 106 clouds with

kinematics compatible with being entrained in a wind with 300 km/s < Vw < 400 km/s and α > 140º Future developments Future developments

Refine kinematic model with more reliable Vw(r) (e.g., Zhang+17)
Run HD simulations of MW wind and compare to cloud observed

property distributions (e.g., NHI, Δv ).

Follow-up interferometric observations of a

few clouds to resolve their morpho-kinematics and compare to simulations

SLIDE 11

Gas in Galaxies - Malta Gas in Galaxies - Malta

HI clouds near the Galactic Center:

Possible tracers for a Milky-Way nuclear wind?

Enrico Di Teodoro

Enrico Di Teodoro

Enrico Di Teodoro

The Role of Gas in Galaxy Dynamics October 3rd, Malta

Galactic Wind In The Milky Way Galactic Wind In The Milky Way

Our Galaxy has its own wind!

Giant lobes extending to 8-10 kpc

Bi-conical outflow generated a few 106 years ago by either SF

(Crocker+11) or SMBH (Yang+12)

Fermi Bubbles

McClure-Griffiths+13 found 86 clouds at the GC not following rotation Entrained in a wind at ~200 km/s ATCA HI Data Wind model

A new Green Bank Telescope survey A new Green Bank Telescope survey ATCA-GC GASS (HI4PI) GBT

(l,b) region Velocity range (km/s) Spatial resolution (arcmin) Channel width (km/s) Sensitivity (Kelvin) ± 4º ± 250 2.4 1.00 0.700 All sky ± 450 15.9 0.82 0.057 ± 10º ± 650 9.1 0.90 0.025

A new survey with 100 m GBT single-dish telescope to widen McClure-Griffiths+13 work High sensitivity

Masking the MW disk emission Masking the MW disk emission GALACTIC DISK ROTATION GALACTIC DISK ROTATION

ANOMALOUS CLOUDS ANOMALOUS CLOUDS GOAL: detecting and studying anomalous clouds above and below the GC

Clouds not in the disk Masking the MW disk by modelling it!

Results: source detection Results: source detection

106 anomalous clouds covering ~ 130 deg2

Results: property distributions Results: property distributions

|VLSR| < 350 km/s Δv ~ 5 - 30 km/s R < ~ 40 pc NHI ~ 5x1018 - 1020

No correlation between FHWM, R or NHI with latitude (height)

Wind kinematic model Wind kinematic model

Describing observed cloud kinematic with a simple a galactic wind model

Vw ≡ Vw(r)

Simplest model defined by 2 parameters: - wind velocity Vw = const

A cloud in (R, z, θ) with V = V(r) can be easily mapped into the (l, b, VLSR) system:

Wind best model Wind best model

Simulating winds with different velocities and opening angles

300 km/s < Vw < 400 km/s α > 140º Best model Vw = 330 km/s

Derived wind properties Derived wind properties

Model-dependent derived properties for a wind with Vw = 330 km/s and α = 140º

Can be supplied by GC with SFR~0.1-0.2 Ms/yr (Crocker12)

Challenge for theory. Destruction timescales are generally lower

Similar to SFR in the CMZ

Clouds likely represent the cold gas component entrained in a hot, starburst-driven nuclear wind

Conclusions Conclusions

They can be used to trace the properties of MW wind

kinematics compatible with being entrained in a wind with 300 km/s < Vw < 400 km/s and α > 140º Future developments Future developments

property distributions (e.g., NHI, Δv ).

few clouds to resolve their morpho-kinematics and compare to simulations

Thank you for your kind attention Thank you for your kind attention