Cúmulos de Galaxias

Cúmulos de Galaxias
COMA
z=0.023
RCS0439.6­2905
z=0.97
•
•
•
Los objetos gravitacionalmente ligados más
masivos en el universo (M~1015 M⊙ ), con
dispersión de velocidad de 800 km s-1
Presentan emisión en rayos-X producida por gas
caliente
Definen un laboratorio natural para estudiar
evolución de galaxias, el medio intergaláctico y la
naturaleza de la materia oscura
MOS
Magellan
Rayos X
de Coma
Rayos X
de Coma
T=88 x 106 K
Cúmulo de Virgo
X-ray
distribución de galaxias
•
Para Virgo M = 1.5 - 5.5 x 1014 M⊙ , y la masa de la
componente gaseosa
–
•
Mg = 4 ­ 5.5 x 1013 M⊙
para cúmulos típicamente MT = 5 - 50 x 1014 M⊙, de
las cuales
5% corresponde a la parte luminosa, i.e. galaxias
10-30% está en gas caliente
el resto en otra forma de materia oscura
The Red-Sequence
Cluster Survey (RCS)
z~1 clusters
Felipe Barrientos (PUC, Chile)
Collaboration
Mike Gladders (OCIW)
Howard Yee (U Toronto)
David Gilbank (U Toronto)
Erica Ellingson (U Colorado)
Henk Hoekstra (U Victoria)
A cluster survey based on the homogeneity of the colors of the
early-type (E/S0) population seen at low and intermediate
redshifts and present in all the clusters found to date.
López-Cruz 1998
These systems have historically played a central role in
observational cosmological. They have also being important in
galaxy evolution, large scale structure and lensing studies.
90 sq deg area
R and z band imaging
R(AB) = 25.4
z(AB) = 23.9
Including
HDFS
XMM-LSS
BOOMERANG
CHANDRA DF
The algorithm searches for overdensities in the
x, y, color and mag space.
2.5 arcmin
RCS0439.6-2905
z=0.951
i'JK composite
seeing ~ 0.4''
Magellan + VLT
RCS0439.6-2905
(central 0.5 Mpc)
(J-K)=0.056 ± 0.014
(I-K)=0.108 ± 0.030
consistent with
zf > 2
Morphology has been determined using a 2-D galaxy
light
Residuals
Original
Simetrized
Bulge
Disk
Models
B+D
Size-magnitude relation
Luminosity evolution... consistent with passive evolution
HST clusters - Schade, Barrientos & Lopez-Cruz (1997)
This is also consistent with the luminosity function
K* = 18.37 ± 0.12
De Propris et al. 1999
Mask
VLT-FORS2
11 objects
in this cluster
Spectrum for
one of the
brightest
galaxies in
RCS0439.6-2905
We have ~20 clusters to date at z~1
Cluster
Bgc
zest
zspec
Nz
Nmem
RCS0220.9­0333
760
0.920
1.026
16
6
RCS0221.7­0322
590
1.057
1.018
47
19
RCS0336.1­2733
750
0.925
0.942
24
5
RCS0350.8­1024
620
0.874
0.945
46
10
RCS0441.2­2858
570
1.037
0.952
16
5
RCS0517.0­4340
870
0.937
0.935
26
6
1010 1.073
1.100
47
7
RCS2112.4­6326
Status of the spectroscopic
redshifts in the RCS
We have practically
doubled the number
of known clusters at
z>0.9
RCS0220.9-0333
z=1.026
1.3 Mpc
Richness vs Velocity dispersion
RCS2118.1-6354
z=0.858
10 members
z<0.6 relation
Blindert et al 2004
RCS0221.7-0322
z=1.018
19 members
Composite z=1 cluster
Composite z=1 cluster
Richness vs Velocity dispersion
Composite z=1
cluster
Summary
Spectroscopy for ~20 z~1 clusters
average velocity dispersion ~800 km/s
early results show they appear to fall on
same richness -- velocity dispersion relation
as z<0.6 clusters
~90% of RCS z~1 clusters are real
130 clusters in RCS1 catalogue with z>0.9
(Bgc>500, significance>3.3-sigma)
RCS2 is coming (800 sq deg)
First X-ray results
(Hicks et al., 2003)
Chandra ACIS observations of 6 clusters at 0.6 < z
< 1.0; all detected!
15-50 Ksec exposures
NOT a representative sample but still diverse- some
with strong lensing, mix of rich and poorer,
concentrated and diffuse
Added 2 clusters from XMM-LSS; Neumann et al.
2003
Lensing clusters:
RCS0224-0002
& RCS1419+5326
(z=0.78)
(z=0.64)
RCS1417+5305 and 0439-2905: z~1.0
Optical and X-ray images not same scale
Lx versus Bgc (optical richness)
Red = CNOC/EMSS
z~0.35
Blue = XMM LSS
Purple = RCS
(0.6 < z < 1.0)
RCS strong
lenses= purple
squares
See also Donahue et al. 1999; Gilbank 2003– optical searches find
candidates which are not X-ray luminous
Lx versus Bgc calculated using only the
red-sequence galaxies
Red = CNOC/EMSS
Blue = XMM LSS
Purple = RCS
RCS giant arcs=
purple squares
No bright arcs =
Purple triangles
Better correlation: blue galaxies in RCS clusters a poorer tracer of mass?
Still discrepancies in several non-lensing clusters
Otros proyectos que incluyen TODO el catálogo
•Propiedades estelares de las galaxias
•Medio interestelar de galaxias
Función de luminosidad
Utilizando un método
estadístico
Gilbank et al 2007
la línea segmentada es
la función de luminosidad
para bajo z, con evolución
pasiva para otros z.
Evolución de la razón
# lum / # débil
downsizing?
Faltan modelos que
predigan esta evolución
Halos de galaxias en cúmulos
Cúmulos de RCS
QSOs de SDSS
Redshift path del survey (z)