Physics – Plasma Physics
Scientific paper
May 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006sptz.prop30483k&link_type=abstract
Spitzer Proposal ID #30483
Physics
Plasma Physics
Scientific paper
Elliptical galaxies provide dust with a unique environment, i.e. old stellar radiation fields without active star formation and interstellar media (ISM) mostly dominated by hot plasma. Small particles such as polycyclic aromatic hydrocarbons (PAHs) and very small grains (VSGs) are expected to be easily destroyed through sputtering by plasma ions. However, in our GO1 program, we have detected PAH emission features and prominent VSG mid-IR excess from X-ray-bright dusty elliptical galaxies. The observed IRS/SL spectra are quite unusual; the usually strong features at 6.2, 7.7, and 8.6 micron are very faint in contrast to prominent features at 11.3 and/or 12.7 micron. A naive interpretation is that the dominant emitters are neutral PAHs. We propose IRS/SL&LL observations of 18 nearby elliptical galaxies with properties similar to the GO1 galaxies, which include IRS/LL observations of the GO1 galaxies; we did not observe them with the IRS/LL. The IRS spectra are ideal to study the environmental effects on PAHs and VSGs; the IRS/SL is well matched to study overall properties of PAHs, while the IRS/LL is crucial to discuss the ionization state of PAHs and the properties of VSGs. Detection of aforementioned unusual PAH features as well as the 16-18 micron plateaus would lay strong constraints on the ionization state of the PAHs and thus their origins. If the results really support the dominance of neutral PAHs, we may have to relinquish a commonly-believed picture that dust and plasma are well mixed in the interstellar space. Then how are the dust spatially separated from the plasma? Detection of prominent mid-IR excess would reasonably explain efficient interaction of the dust with the plasma. Then, how do we sustain the hot plasma against the effective radiative cooling via a dust channel? Observational results with the large sample would give a great impact on the understanding of the dust and plasma physics and the evolutionary history of the ISM of the elliptical galaxies.
Kaneda Hidehiro
Kitayama Tetsu
Okada Yoko
Onaka Takashi
Sakon Itsuki
No associations
LandOfFree
Environmental Effects on PAHs and VSGs in X-ray-bright Dusty Elliptical Galaxies 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 Environmental Effects on PAHs and VSGs in X-ray-bright Dusty Elliptical Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Environmental Effects on PAHs and VSGs in X-ray-bright Dusty Elliptical Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-934415