Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xray.sai.msu.ru/~polar/html/black_hole_coll/okn Дата изменения: Mon Feb 21 15:12:45 2000 Дата индексирования: Tue Oct 2 12:29:40 2012 Кодировка:

Dear Sergei,

I would like to attend the colloquium and present the report.
\title[ AGN Dust Holes ]
{ Reverberation Radii of Dust Holes in Active Galactic Nuclei }

\author[Oknyanksij \& Horne]
{
V. L. Oknyanskij$^{1,2}$,
Keith Horne$^{2}$
\thanks{Send offprint requests to: oknyan@sai.msu.ru},
\\
$^{1}$Sternberg State Astronomical Institute,
Moscow State University, Universitetskij Prospekt 13,
Moscow, 119899, Russia; E-mail: oknyan@sai.msu.ru
\\
$^{2}$Physics and Astronomy,
University of St. Andrews, North Haugh, St.~Andrews KY16~9SS;
E-mail: kdh1@st-and.ac.uk
\\
}

\date{Accepted . Received ; in original form }

\maketitle

\begin{abstract}

We infer the radii of the dust-free zones around NGC~4151,
NGC~7469, and GQ~Comae from cross-correlation time delays
between optical and infrared lightcurves.
The shapes of the auto- and cross-correlation functions
are compared with models to suggest that the dust is distributed
as a flat ring with a hole.
For a sample of 5 active galaxies with redshifts $z<0.165$,
we find that the inferred dust hole radius
increases with ultraviolet luminosity as $\sqrt{L_{uv}}$.
Comparison with predictions of simple dust sublimation theory
indicates a remarkable agreement if we assume a constant dust
grain size.
This suggests that there is a universal dust population in AGNs,
at least for the most robust dust that can survive
at the inner edge of the dust ring.
Should this carry on at higher redshifts, measurements
of optical-infrared time delays be used to calibrate AGN luminosity.
\end{abstract}