42 research outputs found
Universality of dark matter haloes shape over six decades in mass: Insights from the Millennium XXL and SBARBINE simulations
For the last 30 years many observational and theoretical evidences have shown
that galaxy clusters are not spherical objects, and that their shape is much
better described by a triaxial geometry. With the advent of multi-wavelength
data of increasing quality, triaxial investigations of galaxy clusters is
gathering a growing interest from the community, especially in the time of
"precision cosmology". In this work, we aim to provide the first statistically
significant predictions in the unexplored mass range above 3x10^14 Mo/h, using
haloes from two redshifts (z=0 and z=1) of the Millennium XXL simulation. The
size of this cosmological dark matter only simulation (4.1 Gpc) allows the
formation of a statistically significant number of massive cluster scale haloes
(about 500 with M>2x10^15 Mo/h and 780000 with M>10^14 Mo/h). Besides, we aim
to extend this investigation to lower masses in order to look for universal
predictions across nearly six orders of magnitude in mass, from 10^10 to almost
10^16 Mo/h. For this purpose we use the SBARBINE simulations, allowing to model
haloes of masses starting from 10^10 Mo/h. We use an elliptical overdensity
method to select haloes and compute the shapes of the unimodal ones
(approximately 50%), while we discard the unrelaxed. The minor to major and
intermediate to major axis ratio are found to be well described by simple
functional forms. For a given mass we can fully characterize the shape of a
halo and give predictions about the distribution of axis ratios for a given
cosmology and redshift. Moreover, these results are in some disagreement with
the findings of Jing & Suto (2002) which are widely used in the community even
though they have to be extrapolated far beyond their original mass range. This
"recipe" is made available to the community in this paper and in a dedicated
web page.Comment: 13 pages, 16 figure
A young star-forming galaxy at z = 3.5 with an extended Ly\, halo seen with MUSE
Spatially resolved studies of high redshift galaxies, an essential insight
into galaxy formation processes, have been mostly limited to stacking or
unusually bright objects. We present here the study of a typical (L,
M = 6 ) young lensed galaxy at , observed
with MUSE, for which we obtain 2D resolved spatial information of Ly
and, for the first time, of CIII] emission. The exceptional signal-to-noise of
the data reveals UV emission and absorption lines rarely seen at these
redshifts, allowing us to derive important physical properties (T15600
K, n300 cm, covering fraction f) using multiple
diagnostics. Inferred stellar and gas-phase metallicities point towards a low
metallicity object (Z = 0.07 Z and
Z 0.16 Z). The Ly emission extends over
10 kpc across the galaxy and presents a very uniform spectral profile,
showing only a small velocity shift which is unrelated to the intrinsic
kinematics of the nebular emission. The Ly extension is 4 times
larger than the continuum emission, and makes this object comparable to
low-mass LAEs at low redshift, and more compact than the Lyman-break galaxies
and Ly emitters usually studied at high redshift. We model the
Ly line and surface brightness profile using a radiative transfer code
in an expanding gas shell, finding that this model provides a good description
of both observables.Comment: 19 pages, 15 figures, accepted in MNRA
Observations à grand champ d'amas de galaxies
TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocMEUDON-Observatoire (920482302) / SudocSudocFranceF
Etude des courbes de déplétion des comptages profonds de galaxies derrière les amas-lentilles
TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocSudocFranceF
Distribution de masse d'un échantillon d'amas de galaxies déterminée par effet de lentille gravitationnelle faible
TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocSudocFranceF
Contraintes cosmologiques déduites des effets de lentille gravitationnelle dans les amas de galaxies
TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocMEUDON-Observatoire (920482302) / SudocSudocFranceF
Détection et analyse par effet de lentille gravitationnelle d'amas de galaxies
TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF