The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons

Details The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons

2010-03-23

arxiv.org/abs/1003.4516v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

accepted for publication in ApJ, abstract abridged

Scientific paper

We present the results of modeling dust SEDs across the SMC with the aim of mapping the distribution of PAHs in a low-metallicity environment. Using Spitzer Survey of the SMC (S3MC) photometry from 3.6-160 um over the main star-forming regions of the Wing and Bar along with spectral mapping from 5-38 um from the Spitzer Spectroscopic Survey of the SMC (S4MC) in selected regions, we model the dust SED and emission spectrum to determine the fraction of dust in PAHs across the SMC. We use the regions of overlapping photometry and spectroscopy to test the reliability of the PAH fraction as determined from SED fits alone. The PAH fraction in the SMC is low compared to the Milky Way and variable--with relatively high fractions (q_PAH~1-2%) in molecular clouds and low fractions in the diffuse ISM (=0.6%). We use the map of PAH fraction across the SMC to test a number of ideas regarding the production, destruction and processing of PAHs in the ISM. We find weak or no correlation between the PAH fraction and the distribution of carbon AGB stars, the location of supergiant H I shells and young SN remnants, or the turbulent Mach number. We find that the PAH fraction is correlated with CO intensity, peaks in the dust surface density and the molecular gas surface density as determined from 160 um emission. The PAH fraction is high in regions of active star-formation, as predicted by its correlation with molecular gas, but is suppressed in H II regions. Because the PAH fraction in the diffuse ISM is generally very low--in accordance with previous work on modeling the SED of the SMC--and the PAH fraction is relatively high in molecular regions, we suggest that PAHs are destroyed in the diffuse ISM of the SMC and/or PAHs are forming in molecular clouds. We discuss the implications of these observations for our understanding of the PAH life cycle, particularly in low-metallicity galaxies.

Affiliated with

Also associated with

No associations

Rating

The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Spitzer Survey of the Small Magellanic Cloud (S3MC): Insights into the Life-Cycle of Polycyclic Aromatic Hydrocarbons will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-56342