Volume 467, Number 1, May III 2007
|Page(s)||L7 - L10|
|Published online||13 March 2007|
Letter to the Editor
Quasar 3C 298: a test-case for meteoritic nanodiamond 3.5 emission
Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510 México D.F., Mexico e-mail: email@example.com
2 Spitzer Science Center, MS 220-6, California Institute of Technology, Pasadena, CA 91125, USA
3 Dark Cosmology Centre, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
4 European Southern Observatory, Karl-Schwarzschild str. 2, 85748 Garching bei München, Germany
Accepted: 1 March 2007
Aims.We calculate the dust emission expected at 3.43 and 3.53 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.
Key words: galaxies: active / ISM: dust, extinction / infrared: galaxies / ultraviolet: galaxies / quasars: individual: 3C 298
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.