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Modelling photoionisationfeedback with MCRT/MCRHD
From massive star formation to diffuse ionised gas
Bert Vandenbroucke ([email protected])
Tübingen Spring Workshop 2020 on Modeling High-Mass Stellar Feedback
Overview
Method: MCRT/MCRHD
Bondi accretionDiffuse Ionised Gas
Slide 2 of 29
Method: MCRT/MCRHD
Slide 3 of 29
CMacIonize
Regular (or AMR) grid
Voronoi grid
𝐼𝑖 = න𝜈𝑡
∞4𝜋𝐽𝑖 𝜈
ℎ𝜈𝜎 𝜈 d𝜈
≈𝑄
𝑊𝑡𝑉𝑖
𝑗
𝑤𝑗𝑙𝑖𝑗𝜎 𝜈𝑗
BV &Wood (2018)
Slide 4 of 29
Iterative ionization state calculation
Iteratively repeat until convergence(takes approx. 10 iterations)
Slide 5 of 29
Example output
Uniform HII region Turbulent HII region
based on Wood et al. (2013),BV & Sartorio (in prep.)
Slide 6 of 29
Example output (2)
BV et al. (2018)
Hα emission in SILCC DR2
Slide 7 of 29
Algorithmic improvements
2.0Domain-decomposed task-based MCRT
BV, in prep.
Slide 8 of 29
Algorithmic improvements (2)
2.0
BV, in prep.
Slide 9 of 29
MCRHD
Do hydro step
Convert quantities
Do MCRTUpdate
pressure
𝑇 = 𝑇𝑛𝑥𝐻 + 𝑇𝑖 1 − 𝑥𝐻
𝑇𝑛 = 500 K
𝑇𝑖 = 8,000 K
BV & Wood (2018)
Slide 16 of 29
Bondi accretion
Slide 17 of 29
1D Bondi accretion
Isothermal, steady-state accretiononto a point mass
𝑣 𝑟 =−𝐶𝑠 −𝑊−1 −𝜔 𝑟 , 𝑟 ≤ 𝑅𝐵
−𝐶𝑠 −𝑊0 −𝜔 𝑟 , 𝑟 > 𝑅𝐵
𝜔 𝑟 =𝑅𝐵𝑟
4
exp 3 −4𝑅𝐵𝑟
𝜌 𝑟 = −𝜌𝐵𝑅𝐵
2𝐶𝑠𝑟2𝑣 𝑟
Bondi (1952), BV et al. (2019)
Slide 18 of 29
Trapped HII regions
Two-temperature isothermal steady-state accretion
Mestel (1954), Keto (2002,2003), BV et al. (2019)
A similar, closed-form analyticexpression is available
𝑑𝑃
𝑑𝑟< −
𝐺𝑀
𝑟2
Slide 19 of 29
However…
See Lund et al. (2019), BV et al. (2019) for details
Slide 20 of 29
Instability/numerical issue?Slide 21 of 29
3D accretion: D-type expansion in disk
Sartorio et al. (2019)
Slide 22 of 29
3D accretion: trapped HII regions
Sartorio et al. (2019)
Non-spherical trapped and semi-trappedHII regions also possible
Slide 23 of 29
Critical luminosity
Sartorio et al. (2019)
Slide 24 of 29
Diffuse Ionised Gas
Slide 25 of 29
Diffuse Ionised Gas (DIG)
WHAM survey (2003)Dettmar (1990)
Milky Way: WIMNGC 891
Slide 26 of 29
Modelling DIG
Girichidis et al. (2016) BV et al. (2018)
UV radiationfrom O/B stars
SILCC DR2 DIG model
Slide 27 of 29
RHD modelsIonising luminosity per source
Slide 28 of 29
Discussion
MCRT/MCRHD as a method
not so slow as one might think
1D Bondi: instability vs numerical issue
can someone try this with another method?
The DIG as a constraint for feedback
need discs that have a diffuse gas layer to ionize
Slide 29 of 29