P popesso eso a biviano osservatorio di trieste h b hringer mpe m romaniello eso
Download
1 / 20

The RASS-SDSS Galaxy Cluster Survey - PowerPoint PPT Presentation


  • 97 Views
  • Uploaded on

P. Popesso (ESO), A. Biviano (Osservatorio di Trieste), H. B öhringer (MPE), M. Romaniello (ESO). The RASS-SDSS Galaxy Cluster Survey. The Survey:

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'The RASS-SDSS Galaxy Cluster Survey' - sancha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
P popesso eso a biviano osservatorio di trieste h b hringer mpe m romaniello eso

P. Popesso (ESO),

A. Biviano (Osservatorio di Trieste),

H. Böhringer (MPE),

M. Romaniello (ESO).

The RASS-SDSS Galaxy Cluster Survey


The rass sdss galaxy cluster survey

  • The Survey:

  • following the variations of the properties of cluster galaxies with the global properties of the systems (total mass, velocity dispersion, LX, Lop)

  • understanding the selection effects introduced by different cluster detection and selection methods

  • The method & dataset

  • multiwavelenght approach:

    • RASS data for the X-ray properties (LX)

    • SDSS data for optical (Lop) and dynamical (mass, V) cluster properties, spectrophotometric properties of cluster galaxies

  • The cluster samples

  • 130 X-ray selected clusters (the RASS-SDSS Cluster Sample)

  • 137 optically selected (3D overdensity spectroscopically confirmed) Abell Clusters


  • Outlines
    Outlines:

    • Part I

      • universality of the cluster Luminosity Function (LF)

      • the cluster dwarf galaxy population

      • morphology-density relation of the dwarf systems

    • Part II

      • the Abell X-ray Underluminous Clusters (AXU Clusters) and their nature


    The composite cluster luminosity function
    The Composite Cluster Luminosity Function

    The cluster composite LF is obtained by stacking the individual LFs (background subtracted) within the virial radius.

    • Best fit: double Schechter Function

    • at the bright end:

      

      

    • at the faint end:

      

      

      in the r band

      km/s/Mpc )


    Is the cluster lf universal
    Is the cluster LF universal?

    The composite cluster LF, calculated within the virial radius, is a good representation for more than 90% of the clusters, as confirmed by the 2 test.

    When measured within the physical size of the systems (given by r200), the Cluster LF isuniversal

    (Popesso et al. 2005)


    At the bright end
    ...at the bright end

    • Composite cluster LF is able to locate the BCGs.


    At the bright end1
    ...at the bright end

    Composite cluster LF is able to locate the BCGs (Popesso et al. 2005, A&A submitted).

    Solid line LBCG

    Lin & Mohr (2004) , Yang et al. (2005)


    The rass sdss galaxy cluster survey

    ...at the faint end

    DGR=N(-18.5rr 

    • When measured within r200

    • or r500, the DGR is constant


    The rass sdss galaxy cluster survey

    ...at the faint end

    DGR=N(-18.5rr 

    • When measured within r200

    • or r500, the DGR is constant


    When the lfs is measured within a fixed metric aperture of 1 mpc it varies from cluster to cluster
    When the LFs is measured within a fixed metric aperture of 1 Mpc,it varies from cluster to cluster.

    • the overall disagreement about the faint-end slope of the cluster LF in the literature is due to aperture effects


    The cluster lf by galaxy morphological type
    The Cluster LF by Galaxy Morphological type Mpc,

    We use the color cut at u-r=2.22 of Strateva et al. (2001) to distinguish red early type galaxies from blue late type galaxies.

    Early type galaxies Late type galaxies

    Popesso et al. 2005c, astro-ph/0506201



    Conclusions part i
    Conclusions Part I Mpc,

    • bimodal behaviour of the cluster LF (steepening at the faint end)

    • the cluster LF is universal when measured with the virial radius

    • DGR increasing with the clustercentric distance

    • LF steepening due to dwarf early type galaxies which dominate the cluster core (< 0.6 r200)

    • are the dwarf early type galaxies the spheroidal remnants of stripped and faded spirals as predicted by harassment scenario (Moore et al. 1996, 1998)?


    The abell x ray underluminous clusters
    The Abell X-ray Underluminous Clusters Mpc,

    • Do different cluster detection and selection methods select the same cluster population?

      Lx  M2002.04 0.04

      scatter ~60%

      (Popesso et al. 2005, A&A, 433, 431)


    The rass sdss galaxy cluster survey

    • 137 optically selected Abell clusters (3D overdensity spectroscopically confirmed):

    • 88 clusters have clear RASS X-ray counterpart

    • 27 marginally significant ( < 3) detection

    • 24 no X-ray detection

    • (Popesso et al. 2005, A&A submitted)

    • RASS is too shallow to detect such faint X-ray sources (see also Basilakos et al. 2004, Donahue et al. 2003)


    The rass sdss galaxy cluster survey


    The nature of the axu clusters
    The spectroscopically confirmed): nature of the AXU clusters


    The velocity dispersion distribution
    The velocity dispersion distribution spectroscopically confirmed):

    AXU clusters: leptokurtic distribution in the outer region,

    typical of systems in accretion


    Conclusions part ii
    Conclusions Part II spectroscopically confirmed):

    • Optical selection reveals a population of X-ray underluminous (AXU) systems

    • AXU clusters do not follow the LX-M200 relation (mean deviation -1.0 dex)

    • AXU clusters do follow the Lop-M200 relation

    • AXU systems show leptokurtic velocity distribution in the outer regions (systems in accretion?)

    • systems in formation also at low z?

    • multi-wavelength approach is needed for optimizing completeness ans reliability of cluster samples.