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\subsection{Evolution of supermassvie black holes and their connection
to galaxies and dark matter halos} %Please give title here

{\bf{ 
{Prof. Dr. Peter L. Biermann}\\
{MPIfR and Dept for Physics and Astronomy}\\ 
{Universit\"at Bonn}\\
{Auf dem H{\"u}gel 69}\\
{D-53121 BONN}\\
{Telefon: 0228/525-279}\\
{Fax: 0228/525-229}\\
{Email: plbiermann@mpifr-bonn.mpg.de}\\}}

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%  second version Sep 29, 2000 PeBi, comments from HFA twice
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\subsubsection{Abstract}

The ubiquitous occurrence of supermassive black holes in galactic
nuclei needs to be understood, both in terms of how they grow, but
also how they interact with their environment. It seems clear now that
the evolution of black holes and of galactic bulges are intimately
linked. Since one also supposes a connection between dark matter halos
and the formation of galaxies and their bulges the evolution of
galaxies seems to start and end in some form of dark mass: dark matter
halos on large scales and black holes on small scales. This has also
prompted speculations whether black holes could directly accrete from
dark matter halos -- if dark matter is even weakly dissipative.

Here we propose to study the accretion and growth of black holes in
galaxies in their various life phases: during the quiescent evolution
of a galaxy, during a merger with another galaxy, during a starburst,
and during high accretion events in active galaxies.  Necessary for
this is an understanding also how black holes accrete (luminous and
dark matter) and how they interact with each other, since binary black
holes should be common during a certain phase of a merger. In the end
we try to develop a coherent picture for black hole evolution, taking
into account the constraints we obtain from black holes at
various level of activity. This will have an impact not only on the
importance and evolution of dark matter halos on black hole formation,
but on various other questions such as: galaxy evolution, heating of
gas and build-up of magnetic fields in clusters, cosmic filaments and
sheets through AGN activity, which in turn can influence cosmic structure
formation.


\subsubsection{Current status of research}

Black holes are common in all galaxies, that have a bulge, a
spheroidal population of stars.  HST observations and spectroscopy
(Faber et al., Magorrian et al., Kormendy \& Richstone 1995, ARA\&A
33, 581, Kormendy) have found good evidence for the presence of
compact dark masses - presumed to be black holes - in the nuclei of
most galaxies. Recently it was shown (Ferrarese \& Merrit 2000, ApJ
539, L9; Gebhard et al.~2000, ApJ 539, L13) that there is a close
connection between the velocity dispersion of stars in galactic bulges
and the mass of black holes in the center.  Their mass is limited from
above by a ratio of about 1/300 of black hole mass to bulge mass.
There are various models to explain this maximum ratio. One idea is
that through accretion of gas and dust through the galaxy star
formation and strong black hole accretion phases -- where a galaxy
appears as an active galactic nucleus -- occur simultaneously or
subsequently. The ratio of stars expelled into the bulge to the mass
accreted onto the central black hole then approaches a constant
maximum value throughout the lifetime of a galaxy (Wang
\& Biermann, Rees, Merritt).

Another alternative is that most of the mass accreted onto the black
hole throughout a Hubble time is actually due to accretion of dark
matter from dark matter halos of the galaxy. For accretion to occur
this would require that dark matter is at least weakly dissipative.
It can be shown that for certain parameter ranges of dissipative dark
matter the bulge-black hole relation can in principle be recovered to
an order of magnitude. Turned around it can constrain some of the
properties of dark matter (Ostriker 2000, PRL, in press). This is a
rather new idea and physics and consequences of such a dark matter
accretion have not been investigated in greater detail.

In the standard model activity and evolution of black holes is thought
to be via accretion of luminous matter. Over most of their life-times
the activity around the central black hole is weak, but usually
observable in radio-emission.  In fact many of nearby galaxies show
such evidence of weak activity due to low-level accretion in their
nuclei (Falcke et al.~2000, ApJ, in press).  This radio emission can
be attributed to weak jets expelled from accretion flows. A problem is
that the corresponding thermal emission from this accretion is often
absent (Ho 1999, ApJ, 516, 672). Therefore one presumes that accretion
of luminous matter proceeds through a rather `invisible' hot accretion
flow (Narayan et al.~1998, 492, 554) the nature of which is under
strong scrutiny at present and may lead to a number of interesting
elementary particle interactions near the event horizon (Markoff,
Falcke, Biermann 2000, A\&A) .

A perfect example for this is the central black hole in our Galaxy
which provides the best evidence for a black hole and the presence of
very low-level accretion. Accretion seems to be at or even below the
minimum average level needed to explain the black-hole bulge
ratio. The question now is whether this is due to intermittent
low-level accretion events in conjunction with inferred star burst
epochs, or due to some form of invisible accretion.  Therefore the
central black hole, Sgr A*, provides a testbed for a minimum level
physics for what must happen in much more powerful activity, and is
also a baseline to test the possibility of dark matter accretion,
that, if the Ostriker picture were correct, should currently be the
dominant form of accretion.


\subsubsection{Own experience}

We have studied the growth of black holes in galaxies in several papers
(Wang \& Biermann 1998, Wang \& Biermann 2000, and Wang et al. 2000).  We
have studied the ejection and distribution of magnetic fields in the
cosmos also in several papers (Biermann et al. 1997, Ryu et al. 1998).  We
have studied the influence of binary black holes on the surrounding
stellar population (Zier \& Biermann 1999).  We have studied in many
papers the production of energetic particles in the environment of black
holes (Biermann, since 1987 through to today).  We have also studied
the central black holes and their activity and connection to their
environment in many papers (Falcke et al., since 1992).  All these lines
of research continue actively in collaborations with researchers in
Australia, Korea, China, India, Romania, Canada, the USA, and Brasil.


\subsubsection{Goals of the project}

This project is expected to give us a final understanding where black
holes come from, how they grow, how they interact with dark matter,
and how they interact with the growth of structure in the universe. We
try to construct a model for the accretion onto the black hole that
consistently explains the bulge-black hole relation and at the same
time can be used to explain the visible signatures of accreting black
holes. Through this we intend to formulate critical observational tests
that constrain the amount and effects of dark matter accretion onto
black holes and combines black hole and galaxy evolution.


\subsubsection{Estimate of resources expected from DFG}

\begin{itemize}
\item{}  Visiting professor, Prof. Yiping Wang, from China, for one year.
\item{}  Later other visiting profs.
\item{}  Two PhD students for three years each.
\item{}  Support for attending conferences and workshops, especially
those organized by the proposers.
\item{}  Support for short visits of other students and scientists.
\item{}  Support for page charges.
\end{itemize}


\subsubsection{Members of research group relevant for the project}

\begin{itemize}
\item{}  Peter L. Biermann, MPIfR
\item{}  Heino Falcke, MPIfR
\item{}  Students and guests of PLB
\end{itemize}


\subsubsection{Connections to other projects of current SFB proposal}

Various projects in this SFB are concerned with investigating the
level and nature of dark matter in galaxies and galactic halos, being
important for the evolution of galaxies. Here we investigate the
smallest scale in a galaxy where dark matter may be important and
investigate its possible effects. In addition the energy output from
black holes can have significant effects on their environment and is
connected to the evolution of galaxies and galactic halos that we need
to develop a coherent picture of mass distribution in galaxies and
also galaxy clusters.  In unpublished simulations (Ryu, Kang, Biermann) we
have already been able to show, that structure formation can be
influenced at small scales by the activity of galactic nuclei.


\subsubsection{Connection to other current research grants}

We have current programs funded with 
\begin{itemize}
\item{}  Univ. of Adelaide, Australia (R. Protheroe, Austral. S.E.R.C.)
\item{}  Univ. of Daejeon and Pusan, Korea (D. Ryu, H. Kang; KOSEF and
DFG)
\item{}  Univ. of Bukarest, Romania (Erasmus-program, EU)
\item{}  Univ. of Cluj-Napoca, Romania (Erasmus-program, EU, application)
\item{}  Ukraina, Bjelorussia, Russia (INTAS-program, EU; in Western
Europe Sweden, Germany, and Italy; PLB represents the German part here)
\item{}  Russia (INTAS-Program; in Western Europe the UK, France, and
Germany; PLB represents here the German part also; application)
\item{}  Bartol Research Institute, USA (T. Stanev; NATO-grant)
\item{}  Sao Paolo, Brasil (G. Medina-Tanco; application)
\item{}  Astroparticle Physics (BMBF; application; in conjunction
with many groups in Germany)
\end{itemize}

All these programs connect to this research project through the topics of
Cosmic Particle Physics and Cosmic Magnetic Fields.  The emphasis in
these projects is usually on high energy cosmic rays and their interaction
with their environment.


\subsubsection{Background of the proposers}

The research of the proposers can be found on their web-pages under
www.mpifr-bonn.mpg.de/div/theory, which then also refers to the
individual members of the group.

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