Velocity and Ionization Examination in Nebular Turbulent Observations (Velocidad e Ionización: Estudios en Nebulosa de la Turbulencia Observada)
A research initiative (IRyA-UNAM / Mexico) to characterize turbulent velocity fields in H II regions using emission-line observations and derived radial-velocity maps using the second-order structure function. We systematically measure key turbulent parameters such as velocity dispersion in the plane of the sky, the correlation length (energy injection scale), and the spectral slope characterizing the turbulence.
Two pillars:
- Numerical methods and archive that standardizes turbulent parameters across many regions.
- Using the VIENTO pipeline we compute the structure function, fit an heuristic model and recover the turbulent parameters with their confidence intervals using Bayesian statistics.
- Follow-up analyses connecting turbulence to H II region properties (luminosity, size, line-of-sight σ, multi-phase gas, etc.).
Scientific goals:
- Measure, for each region/line/map version the following turbulent parameters:
- Velocity dispersion (plane-of-sky),
$\sigma_\text{POS}$ -
Correlation length,
$r_0$ -
Power-law index,
$m$
- Velocity dispersion (plane-of-sky),
- Our analysis will yield robust correlations between turbulence properties and physical parameters (e.g., luminosity, diameter, and line-of-sight velocity dispersion) of numerous H II regions.
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Projection effects and compressibility:
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$\sigma_\text{POS}$ vs$\sigma_\rho$ 1 -
$\sigma_\text{POS}$ vs$\sigma_\text{LOS}$ $r_0 \ \text{vs} \ \text{Diam}$
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- Theoretical vs observed power law index
- Velocity dispersion - Luminosity,
$\sigma_\text{POS} \ \text{vs} \ I$
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Projection effects and compressibility:
- Analyze the Non-turbulent option for the observed velocity fluctuations.
- Fake maps experiments.
- Muti-scale studies of inhomogeneous turbulence in star forming regions. Such as the fact that the turbulent intensity in Orion seems to be larger in the center than in the outskirts.
- Gas and stars kinematics. Insights into the kinematic relationships between different gas phases.
- Compare methods (e.g., structure function vs. power spectrum vs. SCF/VCA/VCS/Δ-variance) and quantify consistency, biases, and uncertainty.