Simultaneous multicomponent polycyclic aromatic hydrocarbon analysis using an independent component analysis-based latent variable regression

2012 ◽  
Author(s):  
Shouxin Ren ◽  
Ling Gao
Keyword(s):  
Independent Component Analysis ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Latent Variable ◽  
Component Analysis ◽  
Independent Component ◽  
Hydrocarbon Analysis ◽  
Polycyclic Aromatic ◽  
Latent Variable Regression

scholarly journals A principal component analysis of polycyclic aromatic hydrocarbon emission in NGC 2023

2020 ◽  
Vol 500 (1) ◽  
pp. 177-190
Author(s):  
Ameek Sidhu ◽  
Els Peeters ◽  
Jan Cami ◽  
Collin Knight
Keyword(s):  
Principal Component Analysis ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Principal Component ◽  
Component Analysis ◽  
Ionization State ◽  
Polycyclic Aromatic ◽  
Hydrocarbon Emission ◽  
Primary Driver ◽  
Pah Ratios

ABSTRACT We use the measured fluxes of polycyclic aromatic hydrocarbon (PAH) emission features at 6.2, 7.7, 8.6, 11.0, and 11.2 μm in the reflection nebula NGC 2023 to carry out a principal component analysis (PCA) as a means to study previously reported variations in the PAH emission. We find that almost all of the variations (99 per cent) can be explained with just two parameters – the first two principal components (PCs). We explore the characteristics of these PCs and show that the first PC (PC1), which is the primary driver of the variation, represents the amount of emission of a mixture of PAHs with ionized species dominating over neutral species. The second PC (PC2) traces variations in the ionization state of the PAHs across the nebula. Correlations of the PCs with various PAH ratios show that the 6.2 and 7.7 μm bands behave differently than the 8.6 and 11.0 μm bands, thereby forming two distinct groups of ionized bands. We compare the spatial distribution of the PCs to the physical conditions, in particular to the strength of the radiation field, G0, and the G0/nH ratio and find that the variations in PC2, i.e. the ionization state of PAHs are strongly affected by G0 whereas the amount of PAH emission (as traced by PC1) does not depend on G0.

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