Speaker
Tigran Arshakian
(Universität zu Köln)
Description
We develop a wavelet-based cross-correlation (WCC) method to study the correlation between characteristic structures in molecular clouds as a function of scale. The method compares a pair of maps observed in different tracers, at different wavelenghts or in different velocity ranges. Advantages of the WCC: (i) it allows to measure the correlation coefficient and structural offset between two maps as a function of scale, (ii) allows to weight individual pixels by their observational significance, and (iii) is robust against the noise. Application of the WCC to simulated fBm (fractional Brownian motion) maps shows that the cross-correlation coefficient can strongly depend on the scale and correlation coefficient and offset can be recovered robustly regardless of noise. Analysis of the G333 molecular line maps (13CO and C18O) reveals a large scale gradient in the structural distribution. This could indicate a density structure where every core shows a low density tail in a preferred direction. Applications of the WCC to molecular line maps of the Rosette, Cygnus, Perseus, and IC 348 molecular clouds will be also discussed. By tracing the correlated structural changes between different maps of a molecular cloud the WCC detects scales representing the structural changes such as chemical and phase transitions.
Author
Tigran Arshakian
(Universität zu Köln)