Showing papers by "Nabila Aghanim published in 2002"
TL;DR: In this article, a 20 ks XMM observation of the distant cluster RX J1120.1+4318, discovered at z = 0.6 in the SHARC survey, was reported.
Abstract: We report on a 20 ks XMM observation of the distant cluster RX J1120.1+4318, discovered at z = 0.6 in the SHARC survey. The cluster has a regular spherical morphology, suggesting it is in a relaxed state. The combined fit of the EPIC/MOS&pn camera gives a cluster mean temperature of kT = 5.3 +/- 0.5 keV with an iron abundance of 0.47 +/- 0.19. The temperature profile, measured for the first time at such a redshift, is consistent with an isothermal atmosphere up to half the virial radius. The surface brightness profile, measured nearly up to the virial radius, is well fitted by a beta-model, with beta = 0.78(-0.04)(+0.06) and a core radius of theta(c) = 0.44(-0.04)(+0.06) arcmin. We compared the properties of RX J1120.1+4318 with the properties of nearby clusters for two cosmological models. an Einstein-de Sitter Universe and a flat low density Universe with Omega(0) = 0.3. For both models, the scaled emission measure profile beyond the core, the gas mass fraction and luminosity are consistent with the expectations of the self-similar model of cluster formation, although a slightly better agreement is obtained for a low density Universe. There is no evidence of a central cooling flow, in spite of the apparent relaxed state of the cluster. This is consistent with its estimated cooling time, larger than the age of the Universe at the cluster redshift. The entropy profile shows a flat core with a central entropy of similar to140 keV cm(2), remarkably similar to the entropy floor observed in nearby clusters, and a rising profile beyond typically 0.1 virial radius. Implications of our results, in terms of non-gravitational physics in cluster formation, are discussed.
115 citations
TL;DR: In this article, a 20 ksec XMM observation of the distant cluster RXJ1120.1+4318 is reported, which is consistent with an isothermal atmosphere up to half the virial radius.
Abstract: We report on a 20 ksec XMM observation of the distant cluster RXJ1120.1+4318, discovered at z=0.6 in the SHARC survey. The cluster has a regular spherical morphology, suggesting it is in a relaxed state. The combined fit of the EPIC/MOS&pn camera gives a cluster mean temperature of kT=5.3\pm0.5 keV with an iron abundance of 0.47\pm0.19. The temperature profile, measured for the first time at such a redshift, is consistent with an isothermal atmosphere up to half the virial radius. The surface brightness profile, measured nearly up to the virial radius, is well fitted by a beta-model, with beta =0.78[+0.06,-0.04] and a core radius of thetac = 0.44[+0.06,-0.04] arcmin. We compared the properties of RXJ1120.1+4318 with the properties of nearby clusters for two cosmological models: an Einstein - de Sitter Universe and a flat low density Universe with Omega0=0.3. For both models, the scaled emission measure profile beyond the core, the gas mass fraction and luminosity are consistent with the expectations of the self-similar model of cluster formation, although a slightly better agreement is obtained for a low density Universe. There is no evidence of a central cooling flow, in spite of the apparent relaxed state of the cluster. This is consistent with its estimated cooling time, larger than the age of the Universe at the cluster redshift. The entropy profile shows a flat core with a central entropy of ~ 140 keV cm^2, remarkably similar to the entropy floor observed in nearby clusters, and a rising profile beyond typically 0.1 virial radius. Implications of our results, in terms of non-gravitational physics in cluster formation, are discussed.
103 citations
TL;DR: In this paper, the authors used the surface brightness profiles of a sample of 25 distant $(0.3 3.5~\rm keV) clusters, observed with ROSAT, with published temperatures from ASCA.
Abstract: We study the surface brightness profiles of a sample of 25 distant $(0.3 3.5~\rm keV)$ clusters, observed with ROSAT, with published temperatures from ASCA. For both open and flat cosmological models, the derived emission measure profiles are scaled according to the self-similar model of cluster formation. We use the standard scaling relations of cluster properties with redshift and temperature, with the empirical slope of the relation derived by Neumann & Arnaud ([CITE]). Using a $\chi^2$ test, we perform a quantitative comparison of the scaled emission measure profiles of distant clusters with a local reference profile derived from the sample of 15 hot nearby clusters compiled by Neumann & Arnaud (1999), which were found to obey self-similarity. This comparison allows us to both check the validity of the self-similar model across the redshift range $0.04{-}0.8$, and to constrain the cosmological parameters. For a low-density flat universe, the scaled distant cluster data were found to be consistent, both in shape and normalisation, with the local reference profile. It indicates that hot clusters constitute a homologous family up to high redshifts, and gives support to the standard picture of structure formation for the dark matter component. Because of the intrinsic regularity in the hot cluster population, the scaled profiles can be used as distance indicators, the correct cosmology being the one for which the various profiles at different redshifts coincide. The intrinsic limitations of the method, in particular possible systematic errors and biases related to the model uncertainties, are discussed. Using the standard evolution model, the present data allow us to put a tight constraint on $\Omega_{0}$ for a flat Universe: $\Omega_{0}=0.40^{+0.15}_{-0.12}$ at 90% confidence level (statistical errors only). The critical model ($\Omega_{0}=1$) was excluded at the 98% confidence level. Consistently, the observed evolution of the normalisation of the relation was found to comply with the self-similar model for $\Omega_{0}=0.4$, $\Lambda=0.6$. The constraint derived on $\Omega_{0}$ is in remarkable agreement with the constraint obtained from luminosity distances to SNI or from combined analysis of the power spectrum of the 2dF galaxy redshift Survey and the Cosmic Microwave Background anisotropies.
80 citations
TL;DR: In this article, the authors predict the level of the primary anisotropies generated after matter-radiation decoupling, which contributes additional power in the tail of the CMB power spectrum.
Abstract: Forthcoming Cosmic Microwave Background (CMB) experiments will allow us to accurately investigate the power spectrum at very small scales ('>1000). We predict the level of the primary anisotropies, given the actual CMB measurements. The secondary anisotropies generated after matter-radiation decoupling contribute additional power in the tail of the CMB power spectrum. Together with the primary anisotropies, we compute the predicted power spectra for three dominant secondary eects induced by photon scattering. We predict these secondary contributions in flat cosmological models for parameters in agreement (to 2) with the values allowed by current parameter estimates.
13 citations
TL;DR: In this paper, the authors report on a study aiming at characterising the kinetic Sunyaev-Zel'dovich (KSZ) effect through statistical criteria that can blindly indicate the presence of secondary anisotropies due to the KSZ effect buried in the Cosmic Microwave Background (CMB) anisotropic.
Abstract: We report on a study aiming at characterising the kinetic Sunyaev-Zel'dovich (KSZ) effect through statistical criteria that can blindly indicate the presence of secondary anisotropies due to KSZ effect buried in the Cosmic Microwave Background (CMB) anisotropies. We show, using simulated maps, that some properties of the covariance coefficient between thermal Sunyaev-Zel'dovich (TSZ) and the temperature fluctuation map can be used in that purpose.
5 citations
TL;DR: In this article, the authors predict the level of the primary anisotropies, given the actual CMB measurements, and compute the predicted power spectra for three dominant secondary effects induced by photon scattering.
Abstract: Forthcoming CMB experiments will allow us to accurately investigate the power spectrum at very small scales ($\ell > 1000$). We predict the level of the primary anisotropies, given the actual CMB measurements. The secondary anisotropies generated after matter-radiation decoupling contribute additional power in the tail of the CMB power spectrum. Together with the primary anisotropies, we compute the predicted power spectra for three dominant secondary effects induced by photon scattering. We predict these secondary contributions in flat cosmological models for parameters in agreement (to $2\sigma$) with the values allowed by current parameter estimates.
3 citations
06 May 2002
TL;DR: The Diabolo photometer as mentioned in this paper is a dual-channel photometer working at 1.2 and 2.1 mm and dedicated to high angular resolution measurements of the Sunyaev-Zel-dovich effect towards distant clusters.
Abstract: The millimetric atmospheric windows at 1 and 2 mm are interesting targets for cosmological studies. Two broad areas appear leading this field: 1) the search for high redshift star-forming galaxies and 2) the measurement of Sunyaev-Zel’dovich (SZ) effect in clusters of galaxies at all redshifts. The Diabolo photometer is a dual-channel photometer working at 1.2 and 2.1 mm and dedicated to high angular resolution measurements of the Sunyaev-Zel’dovich effect towards distant clusters. It uses 2 by 3 bolometers cooled down to 0.1 K with a compact open dilution cryostat. The high resolution is provided by the IRAM 30 m telescope. The result of several Winter campaigns are reported here, including the first millimetric map of the SZ effect that was obtained by Pointecouteau et al. (2001) [13] on RXJ1347-1145, the non-detection of a millimetric counterpart to the radio decrement towards PC1643+4631 and 2 mm number count upper limits. We discuss limitations in ground-based single-dish millimeter observations, nam...
1 citations
TL;DR: This work analyzes simulated maps of the CMB temperature anisotropies using both wavelet and curvelet transforms and addresses the question to search for, and discriminate between, different non-Gaussian signatures.
Abstract: One of the goals in cosmology is to understand the formation and evolution of the structures resulting from the growth of initial density perturbations. Recent Cosmic Microwave Background (CMB)observations indicate that these pertubations essentially came out of
Gaussian distributed quantum fluctuations in the inflationary scenario. However, topological defects (e.g. cosmic strings) could contribute to the signal. One of their important footprints would be the predicted non-Gaussian distribution of the temperature anisotropies. In addition, other sources of non-Gaussian signatures do contribute to the signal, in particular the Sunyaev-Zel'dovich effect of galaxy clusters.
In this general context and motivated by the future CMB experiments, the question we address is to search for, and discriminate between, different non-Gaussian signatures. To do so, we analyze simulated maps of the CMB temperature anisotropies using both wavelet and curvelet transforms. Curvelets take the form of basis elements which exhibit very high directional sensitivity and are highly anisotropic, which is not the case for wavelets. The sensitivity of both methods is evaluated using simulated data sets.
TL;DR: In this article, the first spatially resolved spectroscopic observations of the Virgo and Coma clusters made with XMM during the PV phase are presented and the implication for the dynamical state of these clusters are briefly discussed.
Abstract: First spatially resolved spectroscopic observations of the Virgo and Coma clusters made with XMM during the PV phase are presented. The implication for the dynamical state of these clusters are briefly discussed.