Abstract
Aims. We calculate the dust emission expected at 3.43 and 3.53 μm if meteoritic (i.e. hydrogenated) nanodiamonds are responsible for most of the far-UV break observed in quasars. Methods. We integrate the UV flux that hydrogenated nanodiamonds must absorb to reproduce the far-UV break. Based on laboratory spectra of H-terminated diamond surfaces, we analyse the radiative energy budget and derive theoretically the IR emission profiles expected for possible C-H surface stretch modes of the diamonds. Results. Using as test case a spectrum of 3C 298 provided by the Spitzer Observatory, we do not find evidence of these emission bands. Conclusions. While diamonds without surface adsorbates remain a viable candidate for explaining the far-UV break observed in quasars, hydrogenated nanodiamonds appear to be ruled out, as they would give rise to IR emission bands, which have not been observed so far.
Originalsprog | Engelsk |
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Tidsskrift | Astronomy and Astrophysics |
Vol/bind | 467 |
Udgave nummer | 1 |
Sider (fra-til) | L7-L10 |
ISSN | 0004-6361 |
DOI | |
Status | Udgivet - 1 maj 2007 |