|
| | | | |
| | | |
| Stat |
Members: 3645
Articles: 2'506'133
Articles rated: 2609
26 April 2024 |
|
| | | | |
|
Article overview
| |
|
|
The innermost region of AGN tori: implications from the HST/NICMOS Type 1 point sources and near-IR reverberation | | Makoto Kishimoto
; Sebastian F. Hoenig
; Thomas Beckert
; Gerd Weigelt
; | | Date: |
4 Sep 2007 | | Abstract: | Spatially resolving the innermost torus in AGN is one of the main goals of
its high-spatial-resolution studies. This could be done in the near-IR
observations of Type 1 AGNs where we see directly the hottest dust grains in
the torus. We discuss two critical issues in such studies. Firstly, we examine
the nuclear point sources in the HST/NICMOS images of nearby Type 1 AGNs, to
evaluate the possible contribution from the central putative accretion disk.
After a careful subtraction of host bulge flux, we show that near-IR colors of
the point sources appear quite interpretable simply as a composite of a
black-body-like spectrum and a relatively blue distinct component as expected
for a torus and an accretion disk, respectively. Our radiative transfer models
for clumpy tori also support this simple two-component interpretation. The
observed near-IR colors suggest a fractional accretion disk contribution of
~25% or less at 2.2 micron. Secondly, we show that the innermost torus radii as
indicated by the recent near-IR reverberation measurements are systematically
smaller by a factor of ~3 than the predicted dust sublimation radius with a
reasonable assumption for graphite grains of sublimation temperature 1500 K and
size 0.05 micron in radius. The discrepancy might indicate a much higher
sublimation temperature or a typical grain size being much larger in the
innermost tori, though the former case appears to be disfavored by the observed
colors of the HST point sources studied above. The near-IR interferometry with
a baseline of ~100 m should be able to provide the important, independent size
measurements, based on the low accretion disk contribution obtained above. | | Source: | arXiv, 0709.0431 | | Services: | Forum | Review | PDF | Favorites | |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
|
News, job offers and information for researchers and scientists:
| |
REGISTER