propagating atomic uncertainties into data analysis
DESCRIPTION
HMI/AIA Science Teams Meeting, Monterey, Feb 2006. Vinay Kashyap, SAO. propagating atomic uncertainties into data analysis. – Kang et al., 2004, XDAP fitting DEMs to high-resolution Chandra and EUVE grating spectra – wavelength errors, missing lines - PowerPoint PPT PresentationTRANSCRIPT
propagating atomic uncertainties into data analysis
– Kang et al., 2004, XDAP
fitting DEMs to high-resolution Chandra
and EUVE grating spectra
– wavelength errors, missing lines
– correlated uncertainties (via MCMC)
pre-compute tables of plausible ion balance
Vinay Kashyap, SAOHMI/AIA Science Teams Meeting, Monterey, Feb 2006
DEM reconstruction cannot be a black box
– fast, simple, robust: pick one
– smoothing: a necessary evil
– error bars.. bands.. bundles.. ropes
– astrophysical limitations:
changing densities and abundances
flows and non-equilibrium ionization
line opacities
atomic data errors
Vinay Kashyap, SAOHMI/AIA Science Teams Meeting, Monterey, Feb 2006
DEM reconstruction cannot be a black box
– fast, simple, robust: pick one
– smoothing: a necessary evil
– error bars.. bands.. bundles.. ropes
– astrophysical limitations:
changing densities and abundances
flows and non-equilibrium ionization
line opacities
atomic data errors
Vinay Kashyap, SAOHMI/AIA Science Teams Meeting, Monterey, Feb 2006
coronal building blocks
– moss DEM
Fletcher & de Pontieu 1999;
Lin et al. 2006
– Sun as a star; stars as the Sun
– the Capella spike at logT=6.8
Vinay Kashyap, SAOHMI/AIA Science Teams Meeting, Monterey, Feb 2006
DEM challenge: lessons learned
MCMC_DEM in PINTofALE
– incorrect by ~3x
– always check for stability of the solution
– watch out for artefacts next to sharp edges
– data can be too good; proportionately more
difficult to get out of local minima
Vinay Kashyap, SAOHMI/AIA Science Teams Meeting, Monterey, Feb 2006