Substructure and galaxy population in a massive post ...clust10/presentations/... · Substructure...
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Substructure and galaxy population in a massive post-merging cluster at z~0.3 F. Ziparo¹ (MPE), H. Boehringer (MPE), F.G. Braglia (UBC), A. Finoguenov (MPE), D. Pierini (MPE) Fig.1 . (B-R) vs. R colour-magnitude diagram for the cluster RXCJ1131.9-1955 imaged with WFI. Red stars are galaxies belonging to the red sequence, green stars are all objects above the red sequence and blue stars are all galaxies identified as blue. The dashed line is the best fit red sequence and the dotted lines represent a scatter of ±3σ. Tab.1. Comparison among 3 clusters of the DXL sample (Braglia et al, 2009). Col. 2 gives the equation of the red sequence for this three clusters, col. 3 the magnitude gap between the two brightest galaxies of the red sequence and col. 4 the dynamical state of the cluster. References Boehringer et al. 2001, A&A, 396, 826 Braglia F. G. et al. 2009, A&A, 500, 947 Finoguenov et al. 2005, A&A, 442, 827 Zhang, Y.-Y. et al. 2006, A&A, 456, 55 The Distant X-ray Luminous (DXL) cluster survey (Zhang et al. 2006) is a homogeneous, flux-limited sample of 13 galaxy clusters with the following characteristics: ⊙ M M KeV T z s erg L X 14 500 45 10 6 . 10 1 . 5 31 . 0 27 . 0 / 10 ≥ - = - = ≥ Fig. 2. Density map for red and blue population of galaxies (distinguished by respective colours). R200 is indicated in green and black contours are relative to X-ray emission. Bottom right: Central part of the cluster RXCJ1131.9-1955: different overdensities are visible and coincident with the location of the brightest galaxies. Fig. 3. Entropy (upper panel) and Temperature maps (lower panel) for the cluster RXCJ1131.9-1955 from Finoguenov et al. (2005). Contours of red galaxies (in black) are overplotted. Tentative interpretation of Entropy, S, and Temperature, TX, maps: ➢ X-ray luminous cluster component coincident with southern galaxy concentration ➢ X-ray surface brightness elongation towards the northern part of the optical cluster ➢ Cool core, cold front and low entropy channel in the southern component ➢ Temperature enhancement in the compression region between N-S merging components CONCLUSIONS RXCJ1131.9-1955 is revealed as a very complex post-merging system with a very X-ray luminous southern component and an extended concentration of optical galaxies in the North. This northern part displays prominent extensions in the galaxy density into large-scale filamentary structures beyond R200. In the central region several galaxy density peaks are marked by bright red galaxies, suggesting a recent build-up of the cluster from several components. RXCJ1131.9-1955 ⨀ M M KeV T z s erg L X 14 500 45 10 0 . 3 2 . 5 4 . 0 2 . 9 3075 . 0 / 10 15 . 0 8 . 1 × ± = ± = = × ± = S TX Abstract Out of the ROSAT-ESO Flux-Limited X-ray (REFLEX) survey (Boehringer et al. 2001) a subsample of the most X-ray luminous galaxy clusters (DXL, Zhang et al. 2006), at z = 0.27 – 0.31 and including a range of different dynamical states and morphologies, was selected. We present the photometric (WFI) results for the DXL post-merging cluster RXCJ1131.9-1955. The cluster members were selected based on their position with respect to the red sequence and subdivided onto red and blue galaxies. The cluster exhibits an offset between X-ray emission and the peak of the member galaxy distribution, a signature of an ongoing cluster merger. We identify two major components associated with concetrations of red galaxies. One component is associated with the main X-ray emission featuring a cool core in the centre, seen as a low-entropy zone, while the other component is associated with an evident extension of X-ray surface brightness. The two components are found on both sides of a large temperature enhancement, probably caused by the shock wave of the colliding clusters. We identify some filaments associated with the cluster that extend beyond R200 and that are populated by red and blue galaxies. The results are compared with those of two other DXL galaxy clusters, a merging one and a relaxed one, in order to understand the co-evolution of galaxies and parent dark-matter halos. Entropy and temperature maps are also taken into account allowing to better analyse the dynamics of the merging cluster. ¹ [email protected]
Transcript of Substructure and galaxy population in a massive post ...clust10/presentations/... · Substructure...
Substructure and galaxy population in a massive postmerging cluster at z~0.3
F. Ziparo¹ (MPE), H. Boehringer (MPE), F.G. Braglia (UBC), A. Finoguenov (MPE), D. Pierini (MPE)
Fig.1 . (BR) vs. R colourmagnitude diagram for the cluster RXCJ1131.91955 imaged with WFI. Red stars are galaxies belonging to the red sequence, green stars are all objects above the red sequence and blue stars are all galaxies identified as blue. The dashed line is the best fit red sequence and the dotted lines represent a scatter of ±3σ.
Tab.1. Comparison among 3 clusters of the DXL sample (Braglia et al, 2009). Col. 2 gives the equation of the red sequence for this three clusters, col. 3 the magnitude gap between the two brightest galaxies of the red sequence and col. 4 the dynamical state of the cluster.
References Boehringer et al. 2001, A&A, 396, 826 Braglia F. G. et al. 2009, A&A, 500, 947 Finoguenov et al. 2005, A&A, 442, 827 Zhang, Y.Y. et al. 2006, A&A, 456, 55
The Distant Xray Luminous (DXL) cluster survey (Zhang et al. 2006) is a homogeneous, fluxlimited sample of 13 galaxy clusters with the following characteristics:
⊙MM
KeVT
z
sergLX
14500
45
10
6.101.5
31.027.0
/10
≥
−=−=
≥
Fig. 2. Density map for red and blue population of galaxies (distinguished by respective colours). R200 is indicated in green and black contours are relative to Xray emission. Bottom right: Central part of the cluster RXCJ1131.91955: different overdensities are visible and coincident with the location of the brightest galaxies.
Fig. 3. Entropy (upper panel) and Temperature maps (lower panel) for the cluster RXCJ1131.91955 from Finoguenov et al. (2005). Contours of red galaxies (in black) are overplotted.
Tentative interpretation of Entropy, S, and Temperature, TX, maps:
➢ Xray luminous cluster component coincident with southern galaxy concentration
➢ Xray surface brightness elongation towards the northern part of the optical cluster
➢ Cool core, cold front and low entropy channel in the southern component
➢ Temperature enhancement in the compression region between NS merging components
CONCLUSIONSRXCJ1131.91955 is revealed as a very complex postmerging system with a very Xray luminous southern component and an extended concentration of optical galaxies in the North. This northern part displays prominent extensions in the galaxy density into largescale filamentary structures beyond R200. In the central region several galaxy density peaks are marked by bright red galaxies, suggesting a recent buildup of the cluster from several components.
RXCJ1131.91955
⨀
MM
KeVT
z
sergLX
14500
45
100.32.5
4.02.9
3075.0
/1015.08.1
×±=
±=
=
×±=
S
TX
AbstractOut of the ROSATESO FluxLimited Xray (REFLEX) survey (Boehringer et al. 2001) a subsample of the most Xray luminous galaxy clusters (DXL, Zhang et al. 2006), at z = 0.27 – 0.31 and including a range of different dynamical states and morphologies, was selected. We present the photometric (WFI) results for the DXL postmerging cluster RXCJ1131.91955. The cluster members were selected based on their position with respect to the red sequence and subdivided onto red and blue galaxies. The cluster exhibits an offset between Xray emission and the peak of the member galaxy distribution, a signature of an ongoing cluster merger. We identify two major components associated with concetrations of red galaxies. One component is associated with the main Xray emission featuring a cool core in the centre, seen as a lowentropy zone, while the other component is associated with an evident extension of Xray surface brightness. The two components are found on both sides of a large temperature enhancement, probably caused by the shock wave of the colliding clusters. We identify some filaments associated with the cluster that extend beyond R200 and that are populated by red and blue galaxies. The results are compared with those of two other DXL galaxy clusters, a merging one and a relaxed one, in order to understand the coevolution of galaxies and parent darkmatter halos. Entropy and temperature maps are also taken into account allowing to better analyse the dynamics of the merging cluster.
