Poster
| Résumé
: MACSJ0717.5+3745
is an X-ray luminous cluster, at a
redshift of z ~ 0.55. Previous
analysis of the galaxy distribution in
its surrounding field revealed the
presence of an elongated structure which
was thought to be a large-scale
filament. By making a weak gravitational
lensing analysis of this cluster and its
surrounding field, we were able to
report the first weak-lensing detection
of a large-scale filament which funnels
the matter onto the core of the cluster.
Our analysis is based on a mosaic of 18
HST/ACS maps, ie an area of ~10×20 arcmin2. To
test the consistency of our weak lensing
analysis we first compared our results
with the strong lensing analysis of
Limousin et al. (2012) of the cluster
core. The weak and strong lensing
density profiles of the cluster core
show a really good agreement. In terms
of mass integrated in a radius of
500 kpc (given the same center),
the strong lensing gives 1.06±0.03 1015 Modor,
while the weak lensing gives 1.04±0.08 1015 Modor.
The excellent agreement between both
values and density profiles confirms the
strength of our weak lensing analysis.
Our analysis detects the MACSJ0717
filament within the 3 sigma detection
contour of the lensing mass
reconstruction, and underlines the
importance of filaments for theoretical
and numerical models of the mass
distribution in the Cosmic Web. We
measured a filament’s projected length
of ~4.5 Mpc,
and a mean density of 2.92±0.66 108 M⊙kpc-2. By
complementing our imaging data with
extensive spectroscopy of galaxies in
the area, and applying plausible
constraints concerning the structure’s
geometry based on its galaxy velocity
field, we construct a 3D model of the
large-scale filament. Within this
framework, we derive a three-dimensional
length of the filament to be
18 Mpc. The filament’s de-projected
density in terms of the critical density
of the Universe is measured as 206±46, a
value that lies at the very high end of
the range predicted by numerical
simulations. |
Bibliographie
- Main
publications
-
Ebeling et al.,
2004, ApJ, 609, L49
- Ebeling
et al., 2007, ApJ, 661, L33
- Jullo
et al., 2007, New Journal of
Physics, 9, 447
- Jullo
& Kneib, 2009, MNRAS, 395, 1319
- Leauthaud
et al., 2007, ApJS, 172, 219
- Leauthaud
et al., 2010, ApJ, 709, 97
- Limousin
et al., 2012, A&A, 544, 71
- Ma
et al., 2008, ApJ, 684, 160
- Ma
et al., 2009, ApJ, 693, L56
- Rhodes
et al., 2000, ApJ, 172, 203
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