The luminosity function of galaxies in elliptical-dominated galaxy groups: clues on the nature of fossil groups
R. Lopes de Oliveira$^1$
C. Mendes de Oliveira$^1$
R. Dupke$^2$
L. Sodr\'e$^1$
E. Cypriano$^1$
%%% Abstract to run on from here. We have started a study of luminosity functions of Fossil Group candidates in order to characterize the faint-end of their galaxy distribution. Here we report on results of nine of them from SDSS photometry and spectroscopy.
lopesdeoliveira.tex
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\title{The luminosity function of galaxies in elliptical-dominated galaxy groups: clues on the nature of fossil groups}   %%% Fill in title
\author{R. Lopes de Oliveira$^1$, C. Mendes de Oliveira$^1$, R. Dupke$^2$, L. Sodr\'e$^1$, E. Cypriano$^1$}   %%% Fill in author names
\affil{1-Universidade de S\~ao Paulo, Brazil; 2-Observat\'orio Nacional, Brazil}    %%% Fill in author affiliations

\begin{abstract} %%% Abstract to run on from here.
We have started a study of luminosity functions of Fossil Group candidates in
order to characterize the faint-end of their galaxy distribution. Here we report
on results of nine of them from SDSS photometry and spectroscopy.
\end{abstract}

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Groups of galaxies optically dominated by an elliptical galaxy 
are classified as Fossil Groups (FGs) if the gap in magnitude between the two brightest
galaxies within R$_{virial}$/2 is greater than 2 in the $r$-band,
and L$_{\rm X}$\,$>$\,10$^{42}$ $h_{50}^{-2}$\,erg\,s$^{-1}$. 
We investigated the luminosity functions (LFs) of 9 elliptical-dominated
galaxy groups which are candidates to FGs from SDSS photometry (0.09\,$<$\,$z$\,$<$ 0.15):
J115305.32+675351.5,
J104548.50+042032.5,
J100742.53+380046.6,
J141004.19 +414520.8,
J085640.72+055347.3,
J081526.59+395935.5,
J101745.57+015645.8,
J153950.78+304303.9, and
J171811.93+563956.1
\citep{Koester07,Santos07}.
The main results are:
(i) A Schechter function describes well the individual LFs, with an $\alpha$-parameter ranging from -1.5 to 0.5; two Schechter functions are needed to describe the composite LF, which is characterized by a decrease in number of galaxies around -20\,$<$\,R\,$<$\,-18.5. 
(ii) There is evidence of merging of the brightest galaxies for a given group, given that $\Delta  r$-mag, i.e. the difference in magnitudes between the M* and the mean absolute magnitude computed from the brightest galaxy of all groups is $\sim$ 3 ($\Delta g$-mag\,$\sim$\,2.3 and $\Delta i$-mag\,$\sim$\,3).
(iii) We derive that the faint-end of the composite LF is well fit by $\alpha$\,$>$\,-1.13 in the $r$-band, and $>$\,-0.8 for the $g$ and $i$ bands. These are comparable within errors to parameters derived for the LF of ``normal'' groups. From the available SDSS spectroscopic redshifts and using the \citet{Carlberg97} relation, we estimate 0.7\,$<$\,R$_{virial}$(Mpc)\,$<$\,1.3 for the groups, with a mean value of $\sim$\,1\,Mpc, which corresponds from the SIS model to 4$\times$10$^{13}$\,$<$\,M$_{virial}$(M$_{\odot}$)\,$<$\,2.3$\times$10$^{14}$. 
Future comparisons of the LF of other systems with that of FGs, determined from a larger sample will provide insights into the nature of these systems.


\acknowledgements %%% Text of acknowledgements runs on after this command.
We acknowledge financial support from the Brazilian agencies FAPESP and CNPq (R.L.O.: FAPESP Postdoctoral Research Fellow grant 2007/04710-1). This work is based on observations of the SDSS survey.

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\begin{thebibliography}{}
\bibitem[Carlberg et al.(1997)]{Carlberg97}Carlberg, R. G., Yee, H. K. C., Ellingson, E. et al. 1997, ApJ, 485, 13
\bibitem[Koester et al.(2007)]{Koester07}Koester, B., McKay, T. A., Annis, J., et al. 2007, ApJ, 660, 239
\bibitem[Santos et al.(2007)]{Santos07}Santos, W. A., Mendes de Oliveira, C. \& Sodr\'e, L. 2007, AJ, 134, 1551
\bibitem[Zandivarez et al.(2006)]{Zandivarez06}Zandivarez, A., Mart\'inez, H. J. \& Merch\'an, M. E. 2006, ApJ, 650, 137

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0909.2612.extracted_bib
\begin{thebibliography}{}
\bibitem[Carlberg et al.(1997)]{Carlberg97}Carlberg, R. G., Yee, H. K. C., Ellingson, E. et al. 1997, ApJ, 485, 13
\bibitem[Koester et al.(2007)]{Koester07}Koester, B., McKay, T. A., Annis, J., et al. 2007, ApJ, 660, 239
\bibitem[Santos et al.(2007)]{Santos07}Santos, W. A., Mendes de Oliveira, C. \& Sodr\'e, L. 2007, AJ, 134, 1551
\bibitem[Zandivarez et al.(2006)]{Zandivarez06}Zandivarez, A., Mart\'inez, H. J. \& Merch\'an, M. E. 2006, ApJ, 650, 137

\end{thebibliography}