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Studying Clusters of Galaxies with IFUs. Studying Galaxy Clusters with IFUs. Marco Scodeggio, Bianca Garilli, Dario Maccagni, Micol Bolzonella, Paolo Franzetti, Alessandra Zanichelli *. IASF - CNR, Milano, Italy *IRA - CNR, Bologna, Italy. Euro3D Kick-off Meeting, IAC July 2002.
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Studying Clusters of Galaxies with IFUs Studying Galaxy Clusters with IFUs Marco Scodeggio, Bianca Garilli, Dario Maccagni, Micol Bolzonella, Paolo Franzetti, Alessandra Zanichelli* IASF - CNR, Milano, Italy *IRA - CNR, Bologna, Italy Euro3D Kick-off Meeting, IAC July 2002
Why study clusters of galaxies 1. for themselves, as tracers of the large-scale distribution of matter in the Universe 2. for the galaxies they "contain", to study the processes of galaxy formation and evolution Euro3D Kick-off Meeting, IAC July 2002
REFLEX Clusters (Guzzo 2002) 2dF Galaxies (Peacock et al. 2001) Euro3D Kick-off Meeting, IAC July 2002
Despite the different density of objects, galaxies and clusters trace the same 3D structures, with clusters covering (potentially) larger volumes Notice how the best fitting model is just one, the same for galaxies and for clusters, scaled to the different "mass" of these objects (Guzzo 2002) Euro3D Kick-off Meeting, IAC July 2002
Evolution of cluster abundance with redshift No evolution for a low W0 Universe Strong evolution for a high W0 Universe (Bahcall & Fan 1997) Euro3D Kick-off Meeting, IAC July 2002
Galaxy properties: the Fundamental Plane From the Virial theorem we have: GM/<R> = kE<V2>/2 The observed quantities can be related to the physical ones via Re = kR<R> ; s2 = kV<V2> ; L = kLRe2 S And one derives the relation: Re = kFP s2 S-1 (M/L)-1 To be compared with the observed one: Log Re = a Log s + b Log S with coefficients a Y 1.5 and b Y - 0.85 Euro3D Kick-off Meeting, IAC July 2002
Local Universe High -z Universe (Kelson et al. 1997) (Scodeggio et al. 1997) Euro3D Kick-off Meeting, IAC July 2002
Evolution of the M/L ratio with redshift, and implications on the formation epoch of cluster elliptical galaxies (van Dokkum 2001) Euro3D Kick-off Meeting, IAC July 2002
How to study clusters of galaxies 1. from a survey, build a candidates sample 2. confirm spectroscopically the candidates (and get a measure of the cluster redshift) 3. study in detail the cluster and its galaxies (obtain spectra for many cluster galaxies) Euro3D Kick-off Meeting, IAC July 2002
The spectroscopic work is trivial at low redshift (z < 0.1) but becomes very difficult at medium / high redshift (z > 0.5) (Dickinson 1997) Euro3D Kick-off Meeting, IAC July 2002
Targetting cluster galaxies: the MOS case Euro3D Kick-off Meeting, IAC July 2002
Targetting cluster galaxies: the IFU case Euro3D Kick-off Meeting, IAC July 2002
IFU dominates over MOS for clusters work Same limiting magnitude Same exposure time Euro3D Kick-off Meeting, IAC July 2002
Conclusions 1. MOS observations are not well suited for studying medium/ high redshift clusters (z > 0.5), as they not even always provide enough redshifts to confirm the cluster presence 2. IFU observations, on the contrary, always provide enough data to confirm the cluster presence, and most of the time also enough data to study the cluster properties and build a significant sample of cluster galaxies 3. The number of target cluster galaxies in deep IFU observations depends very mildly on the cluster redshift Euro3D Kick-off Meeting, IAC July 2002
To be continued.... Euro3D Kick-off Meeting, IAC July 2002