Yoel Rephaeli

Tel Aviv University, Tell Afif, Tel Aviv, Israel

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Publications (166)587.68 Total impact

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    ABSTRACT: Clusters of galaxies are uniquely important cosmological probes of the evolution of the large scale structure, whose diagnostic power depends quite significantly on the ability to reliably determine their masses. Clusters are typically modeled as spherical systems whose intracluster gas is in strict hydrostatic equilibrium (i.e., the equilibrium gas pressure is provided entirely by thermal pressure), with the gravitational field dominated by dark matter, assumptions that are only rough approximations. In fact, numerical simulations indicate that galaxy clusters are typically triaxial, rather than spherical, and that turbulent gas motions (induced during hierarchical merger events) provide an appreciable pressure component. Extending our previous work, we present results of a joint analysis of X-ray, weak and strong lensing measurements of Abell 1689. The quality of the data allows us to determine both the triaxial shape of the cluster and the level of non-thermal pressure that is required if the intracluster gas is in hydrostatic equilibrium. We find that the dark matter axis ratios are 1.24 +/- 0.13 and 2.02 +/- 0.01 on the plane of the sky and along the line of sight, respectively, and that about 20% of the pressure is non-thermal. Our treatment demonstrates that the dynamical properties of clusters can be determined in a (mostly) bias-free way, enhancing the use of clusters as more precise cosmological probes.
    Monthly Notices of the Royal Astronomical Society 03/2011; 416(4). DOI:10.1111/j.1365-2966.2011.19175.x · 5.23 Impact Factor
  • M. Shimon, S. Sadeh, Y. Rephaeli
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    ABSTRACT: The growth of structure in the Universe begins at the time of radiation–matter equality, which corresponds to energy scales of ∼0.4 eV. All tracers of dark matter evolution are expected to be sensitive to neutrino masses on this and smaller scales. Here we explore the possibility of using cluster number counts and power spectrum obtained from ongoing Sunyaev–Zel’dovich (SZ) surveys to constrain neutrino masses. Specifically, we forecast the capability of ongoing measurements with the Planck satellite and the ground-based South Pole Telescope (SPT) experiment, as well as measurements with the proposed Epic satellite, to set interesting bounds on neutrino masses from their respective SZ surveys. We also consider an Atacama Cosmology Telescope (ACT)-like cosmic microwave background (CMB) experiment that covers only a few hundred deg2 also to explore the trade-off between the survey area and sensitivity and what effect this may have on inferred neutrino masses. We find that for such an experiment a shallow survey is preferable over a deep and low-noise scanning scheme. The precision with which the total neutrino mass can be determined from SZ number counts and power spectrum is limited mostly by uncertainties in the basic cosmological parameters, the mass function of clusters and their mean gas mass fraction; all these are explicitly accounted for in our statistical Fisher matrix treatment. We find that projected results from the Planck SZ survey can, in principle, be used to determine the total neutrino mass with a (1σ) uncertainty of 0.28 eV, if the detection limit of a cluster is set at the 5σ significance level. This is twice as large as the limits expected from Planck CMB lensing measurements. The corresponding limits from the SPT and Epic surveys are ∼0.44 and ∼0.12 eV, respectively. Mapping an area of 200 deg2, ACT measurements are predicted to attain a 1σ uncertainty of 0.61 eV; expanding the observed area to 4000 deg2 will decrease the uncertainty to 0.36 eV.
    Monthly Notices of the Royal Astronomical Society 01/2011; 412(3):1895 - 1904. DOI:10.1111/j.1365-2966.2010.18026.x · 5.23 Impact Factor
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    Massimo Persic, Yoel Rephaeli
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    ABSTRACT: Adopting the convection-diffusion model for energetic electron and proton propagation, and accounting for all the relevant hadronic and leptonic processes, the steady-state energy distributions of these particles in the starburst galaxies M82 and NGC253 can be determined with a detailed numerical treatment. The electron distribution is directly normalized by the measured synchrotron radio emission from the central starburst region; a commonly expected theoretical relation is then used to normalize the proton spectrum in this region, and a radial profile is assumed for the magnetic field. The resulting radiative yields of electrons and protons are calculated: the predicted >100MeV and >100GeV fluxes are in agreement with the corresponding quantities measured with the orbiting Fermi telescope and the ground-based VERITAS and HESS Cherenkov telescopes. The cosmic-ray energy densities in central regions of starburst galaxies, as inferred from the radio and gamma-ray measurements of (respectively) non-thermal synchrotron and neutral-pion-decay emission, are U=O(100) eV/cm3, i.e. at least an order of magnitude larger than near the Galactic center and in other non-very-actively star-forming galaxies. These very different energy density levels reflect a similar disparity in the respective supernova rates in the two environments. A L(gamma) ~ SFR^(1.4) relationship is then predicted, in agreement with preliminary observational evidence.
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    ABSTRACT: We use extensive measurements of the cluster A1689 to assess the expected similarity in the dynamics of galaxies and dark matter (DM) in their motion as collisionless "particles" in the cluster gravitational potential. To do so, we derive the radial profile of the specific kinetic energy of the cluster galaxies from the Jeans equation and observational data. Assuming that the specific kinetic energies of galaxies and DM are roughly equal, we obtain the mean value of the DM velocity anisotropy parameter and the DM density profile. Since this deduced profile has a scale radius that is higher than inferred from lensing observations, we tested the validity of the assumption by repeating the analysis using results of simulations for the profile of the DM velocity anisotropy. Results of both analyses indicate a significant difference between the kinematics of galaxies and DM within r 0.3r vir. This finding is also reflected in the shape of the galaxy number density profile, which flattens markedly with respect to the steadily rising DM profile at small radii. Thus, r ~ 0.3r vir seems to be a transition region interior to which collisional effects significantly modify the dynamical properties of the galaxy population with respect to those of DM in A1689.
    The Astrophysical Journal 01/2011; 728(1):40. DOI:10.1088/0004-637X/728/1/40 · 6.28 Impact Factor
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    Irina Dvorkin, Yoel Rephaeli
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    ABSTRACT: We model the formation and evolution of galaxy clusters in the framework of an extended dark matter halo merger-tree algorithm that includes baryons and incorporates basic physical considerations. Our modified treatment is employed to calculate the probability density functions of the halo concentration parameter, intracluster gas temperature, and the integrated Comptonization parameter for different cluster masses and observation redshifts. Scaling relations between cluster mass and these observables are deduced that are somewhat different than previous results. Modeling uncertainties in the predicted probability density functions are estimated. Our treatment and the insight gained from the results presented in this paper can simplify the comparison of theoretical predictions with results from ongoing and future cluster surveys.
    Monthly Notices of the Royal Astronomical Society 10/2010; 412(1). DOI:10.1111/j.1365-2966.2010.17945.x · 5.23 Impact Factor
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    M. Shimon, S. Sadeh, Y. Rephaeli
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    ABSTRACT: The growth of structure in the universe begins at the time of radiation-matter equality, which corresponds to energy scales of $\sim 0.4 eV$. All tracers of dark matter evolution are expected to be sensitive to neutrino masses on this and smaller scales. Here we explore the possibility of using cluster number counts and power spectrum obtained from ongoing SZ surveys to constrain neutrino masses. Specifically, we forecast the capability of ongoing measurements with the PLANCK satellite and the ground-based SPT experiment, as well as measurements with the proposed EPIC satellite, to set interesting bounds on neutrino masses from their respective SZ surveys. We also consider an ACT-like CMB experiment that covers only a few hundred ${\rm deg^{2}}$ also to explore the tradeoff between the survey area and sensitivity and what effect this may have on inferred neutrino masses. We find that for such an experiment a shallow survey is preferable over a deep and low-noise scanning scheme. We also find that projected results from the PLANCK SZ survey can, in principle, be used to determine the total neutrino mass with a ($1\sigma$) uncertainty of $0.28 eV$, if the detection limit of a cluster is set at the $5\sigma$ significance level. This is twice as large as the limits expected from PLANCK CMB lensing measurements. The corresponding limits from the SPT and EPIC surveys are $\sim 0.44 eV$ and $\sim 0.12 eV$, respectively. Mapping an area of 200 deg$^{2}$, ACT measurements are predicted to attain a $1\sigma$ uncertainty of 0.61 eV; expanding the observed area to 4,000 deg$^{2}$ will decrease the uncertainty to 0.36 eV. Comment: 14 pages, 1 figure, 6 tables
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    ABSTRACT: We present a strong-lensing analysis of the galaxy cluster MS 1358.4+6245 ($z=0.33$), in deep 6-band ACS/HST imaging. In addition to the well-studied system at $z=4.92$, our modelling method uncovers 19 new multiply-lensed images so that a total of 23 images and their redshifts are used to accurately constrain the inner mass distribution. We derive a relatively shallow inner mass profile, $d\log \Sigma/d\log r\simeq -0.33 \pm0.05$ ($r<200$ kpc), with a much higher magnification than estimated previously by models constrained only by the $z=4.92$ system. Using these many new images we can apply a non-parametric adaptive-grid method, which also yields a shallow mass profile without prior assumptions, strengthening our conclusions. The total magnification of the $z_s=4.92$ galaxy is high, about a $\sim100\times$ over its four images, so that the inferred source size, luminosity and star-formation rate are about $\sim5\times$ smaller than previous estimates, corresponding to a dwarf-sized galaxy of radius $\simeq1$ kpc. A detailed image of the interior morphology of the source is generated with a high effective resolution of only $\simeq$50 pc, thanks to the high magnification and to the declining angular diameter distance above $z\sim1.5$ for the standard cosmology, so that this image apparently represents the best resolved object known at high redshift.
    Monthly Notices of the Royal Astronomical Society 09/2010; 413(3). DOI:10.1111/j.1365-2966.2011.18252.x · 5.23 Impact Factor
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    ABSTRACT: We report recent progress in testing the scaling law of the CMB temperature as a function of redshift. By using an up-to-date sample of multifrequency SZ data of 13 galaxy clusters, we have extracted the CMB temperature values at different redshifts, and we found no significant evidence of deviations from the linear scaling, as expected in the framework of standard cosmology. The robustness of the method, even with the limitations set by the current level of the observational uncertainties, has been tested by using two different approaches. Therefore, we expect a significant improvement of the present results from currently active and near-future SZ experiments.
    Nuovo Cimento- Societa Italiana di Fisica Sezione B 05/2010; DOI:10.1393/ncb/i2010-10867-5 · 0.27 Impact Factor
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    ABSTRACT: The inner mass-profile of the relaxed cluster Abell 1703 is analysed by two very different strong-lensing techniques applied to deep ACS and WFC3 imaging. Our parametric method has the accuracy required to reproduce the many sets of multiple images, based on the assumption that mass approximately traces light. We test this assumption with a fully non-parametric, adaptive grid method, with no knowledge of the galaxy distribution. Differences between the methods are seen on fine scales due to member galaxies which must be included in models designed to search for lensed images, but on the larger scale the general distribution of dark matter is in good agreement, with very similar radial mass profiles. We add undiluted weak-lensing measurements from deep multi-colour Subaru imaging to obtain a fully model-independent mass profile out to the virial radius and beyond. Consistency is found in the region of overlap between the weak and strong lensing, and the full mass profile is well-described by an NFW model of a concentration parameter, $c_{\rm vir}\simeq 7.15\pm0.5$ (and $M_{vir}\simeq 1.22\pm0.15 \times 10^{15}M_{\odot}/h$). Abell 1703 lies above the standard $c$--$M$ relation predicted for the standard $\Lambda$CDM model, similar to other massive relaxed clusters with accurately determined lensing-based profiles.
    Monthly Notices of the Royal Astronomical Society 04/2010; 408(3). DOI:10.1111/j.1365-2966.2010.17258.x · 5.23 Impact Factor
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    ABSTRACT: We present our recently developed {\em galcon} approach to hydrodynamical cosmological simulations of galaxy clusters - a subgrid model added to the {\em Enzo} adaptive mesh refinement code - which is capable of tracking galaxies within the cluster potential and following the feedback of their main baryonic processes. Galcons are physically extended galactic constructs within which baryonic processes are modeled analytically. By identifying galaxy halos and initializing galcons at high redshift ($z \sim 3$, well before most clusters virialize), we are able to follow the evolution of star formation, galactic winds, and ram-pressure stripping of interstellar media, along with their associated mass, metals and energy feedback into intracluster (IC) gas, which are deposited through a well-resolved spherical interface layer. Our approach is fully described and all results from initial simulations with the enhanced {\em Enzo-Galcon} code are presented. With a galactic star formation rate derived from the observed cosmic star formation density, our galcon simulation better reproduces the observed properties of IC gas, including the density, temperature, metallicity, and entropy profiles. By following the impact of a large number of galaxies on IC gas we explicitly demonstrate the advantages of this approach in producing a lower stellar fraction, a larger gas core radius, an isothermal temperature profile in the central cluster region, and a flatter metallicity gradient than in a standard simulation.
    The Astrophysical Journal 04/2010; 716(2). DOI:10.1088/0004-637X/716/2/918 · 6.28 Impact Factor
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    Massimo Persic, Yoel Rephaeli
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    ABSTRACT: Cosmic-ray energy densities in central regions of starburst galaxies, as inferred from radio and -ray measurements of, respectively, non-thermal synchrotron and π0-decay emission, are typically , i.e. typically at least an order of magnitude larger than near the Galactic Centre and in other not-very-actively star-forming galaxies. We first show that these very different energy density levels reflect a similar disparity in the respective supernova (SN) rates in the two environments, which is not unexpected given the SN origin of (Galactic) energetic particles. As a consequence of this correspondence, we then demonstrate that there is partial quantitative evidence that the stellar initial mass function (IMF) in starburst nuclei has a low-mass truncation at ∼2 M⊙, as predicted by theoretical models of turbulent media, in contrast with the much smaller value of 0.1 M⊙ that characterizes the low-mass cut-off of the stellar IMF in ‘normal’ galactic environments.
    Monthly Notices of the Royal Astronomical Society 02/2010; 403(3):1569 - 1576. DOI:10.1111/j.1365-2966.2009.16218.x · 5.23 Impact Factor
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    ABSTRACT: We present the results of a strong-lensing analysis of a complete sample of 12 very luminous X-ray clusters at $z>0.5$ using HST/ACS images. Our modelling technique has uncovered some of the largest known critical curves outlined by many accurately-predicted sets of multiple images. The distribution of Einstein radii has a median value of $\simeq28\arcsec$ (for a source redshift of $z_{s}\sim2$), twice as large as other lower-$z$ samples, and extends to $55\arcsec$ for MACS J0717.5+3745, with an impressive enclosed Einstein mass of $7.4\times10^{14} M_{\odot}$. We find that 9 clusters cover a very large area ($>2.5 \sq \arcmin$) of high magnification ($\mu > \times10$) for a source redshift of $z_{s}\sim8$, providing primary targets for accessing the first stars and galaxies. We compare our results with theoretical predictions of the standard $\Lambda$CDM model which we show systematically fall short of our measured Einstein radii by a factor of $\simeq1.4$, after accounting for the effect of lensing projection. Nevertheless, a revised analysis once arc redshifts become available, and similar analyses of larger samples, are needed in order to establish more precisely the level of discrepancy with $\Lambda$CDM predictions.
    Monthly Notices of the Royal Astronomical Society 02/2010; 410(3). DOI:10.1111/j.1365-2966.2010.17574.x · 5.23 Impact Factor
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    Yoel Rephaeli, Yinon Arieli, Massimo Persic
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    ABSTRACT: Measurement sensitivity in the energetic γ-ray region has improved considerably and is about to increase further in the near future, motivating a detailed calculation of high-energy (HE; ≥100 MeV) and very high-energy (VHE; ≥100 GeV) γ-ray emission from the nearby starburst galaxy NGC 253. Adopting the convection–diffusion model for energetic electron and proton propagation, and accounting for all the relevant hadronic and leptonic processes, we determine the steady-state energy distributions of these particles by a detailed numerical treatment. The electron distribution is directly normalized by the measured synchrotron radio emission from the central starburst region; a commonly expected theoretical relation is then used to normalize the proton spectrum in this region. Doing so fully specifies the electron spectrum throughout the galactic disc and, with an assumed spatial profile of the magnetic field, the predicted radio emission from the full disc matches well the observed spectrum, confirming the validity of our treatment. The resulting radiative yields of both particles are calculated; the integrated HE and VHE fluxes from the entire disc are predicted to be f(≥100 MeV) ≃ (1.8+1.5−0.8) × 10−8 cm−2 s−1 and f(≥100 GeV) ≃ (3.6+3.4−1.7) × 10−12 cm−2 s−1, with a central magnetic field value B0≃ 190 ± 10 μG. We discuss the feasibility of measuring emission at these levels with the space-borne Fermi and ground-based Cherenkov telescopes.
    Monthly Notices of the Royal Astronomical Society 12/2009; 401(1):473 - 478. DOI:10.1111/j.1365-2966.2009.15661.x · 5.23 Impact Factor
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    ABSTRACT: We have determined the cosmic microwave background temperature, T(z), at redshifts in the range 0.023-0.546, from multi-frequency measurements of the Sunyaev-Zeldovich (S-Z) effect toward 13 clusters. We extract the parameter α in the redshift scaling T(z) = T 0(1 + z)1–α, which contrasts the prediction of the standard model (α = 0) with that in non-adiabatic evolution conjectured in some alternative cosmological models. The statistical analysis is based on two main approaches: using ratios of the S-Z intensity change, ΔI, thus taking advantage of the weak dependence of the ratios on intracluster gas properties, and using directly the ΔI measurements. In the former method, dependence on the Thomson optical depth and gas temperature is only second order in these quantities. In the second method, we marginalize over these quantities which appear to first order in the intensity change. The marginalization itself is done in two ways—by direct integrations and by a Monte Carlo Markov chain approach. Employing these different methods we obtain two sets of results that are consistent with α = 0, in agreement with the prediction of the standard model.
    The Astrophysical Journal 10/2009; 705(2):1122. DOI:10.1088/0004-637X/705/2/1122 · 6.28 Impact Factor
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    ABSTRACT: We have determined the CMB temperature, T(z), at redshifts in the range 0.023-0.546, from multi-frequency measurements of the S-Z effect towards 13 clusters. We extract the parameter α in the redshift scaling T(z) = T0(1 + z) 1−α, which contrasts the prediction of the standard model (α = 0) with that in non-adiabatic evolution conjectured in some alternative cosmological models. The statistical analysis is based on two main approaches: using ratios of the S-Z intensity change, ∆I, thus taking advantage of the weak dependence of the ratios on IC gas properties, and using directly the ∆I measurements. In the former method dependence on the Thomson optical depth and gas temperature is only second order in these quantities. In the second method we marginalize over these quantities which appear to first order in the intensity change. The marginalization itself is done in two ways- by direct integrations, and by a Monte Carlo Markov Chain approach. Employing these different methods we obtain two sets of results that are consistent with α = 0, in agreement with the prediction of the standard model. Subject headings: cosmic microwave background — cosmology:observations — galaxies:clusters
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    ABSTRACT: We identify 13 sets of multiply-lensed galaxies around MACS J0717.5+3745 ($z=0.546$), outlining a very large tangential critical curve of major axis $\sim2.8\arcmin$, filling the field of HST/ACS. The equivalent circular Einstein radius is $\theta_{e}= 55 \pm 3\arcsec$ (at an estimated source redshift of $z_{s}\sim2.5$), corresponding to $r_e\simeq 350\pm 20 kpc$ at the cluster redshift, nearly three times greater than that of A1689 ($r_e\simeq 140 kpc$ for $z_{s}=2.5$). The mass enclosed by this critical curve is very large, $7.4\pm 0.5 \times 10^{14}M_{\odot}$ and only weakly model dependent, with a relatively shallow mass profile within $r<250 kpc$, reflecting the unrelaxed appearance of this cluster. This shallow profile generates a much higher level of magnification than the well known relaxed lensing clusters of higher concentration, so that the area of sky exceeding a magnification of $>10\times$, is $\simeq 3.5\sq\arcmin$ for sources with $z\simeq 8$, making MACS J0717.5+3745 a compelling target for accessing faint objects at high redshift. We calculate that only one such cluster, with $\theta_{e}\ge 55\arcsec$, is predicted within $\sim 10^7$ Universes with $z\ge 0.55$, corresponding to a virial mass $\ge 3\times 10^{15} M_{\odot}$, for the standard $\Lambda CDM$ (WMAP5 parameters with $2\sigma$ uncertainties).
    The Astrophysical Journal 07/2009; 707(1). DOI:10.1088/0004-637X/707/1/L102 · 6.28 Impact Factor
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    ABSTRACT: Weak lensing work can be badly compromised by unlensed foreground and cluster members which dilute the true lensing signal. We show how the lensing amplitude in multi-colour space can be harnessed to securely separate cluster members from the foreground and background populations for three massive clusters, A1703 (z=0.258), A370 (z=0.375) and RXJ1347-11 (z=0.451) imaged with Subaru. The luminosity functions of these clusters when corrected for dilution, show similar faint-end slopes, \alpha ~= -1.0, with no marked faint-end upturn to our limit of M_R ~= -15.0, and only a mild radial gradient. In each case, the radial profile of the M/L ratio peaks at intermediate radius, ~=0.2r_{vir}, at a level of 300-500(M/L_R)_\odot, and then falls steadily towards ~100(M/L_R)_{\odot} at the virial radius, similar to the mean field level. This behaviour is likely due to the relative paucity of central late-type galaxies, whereas for the E/S0-sequence only a mild radial decline in M/L is found for each cluster. We discuss this behaviour in the context of detailed simulations where predictions for tidal stripping may now be tested accurately with observations.
    Monthly Notices of the Royal Astronomical Society 06/2009; 405. DOI:10.1111/j.1365-2966.2010.16491.x · 5.23 Impact Factor
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    Doron Lemze, Sharon Sadeh, Yoel Rephaeli
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    ABSTRACT: Extensive measurements of the X-ray background (XRB) yield a reasonably reliable characterisation of its basic properties. Having resolved most of the cosmic XRB into discrete sources, the levels and spectral shapes of its main components can be used to probe both the source populations and also alternative cosmological and large-scale structure models. Recent observations of clusters seem to provide evidence that clusters formed earlier and are more abundant than predicted in the standard $\Lambda$CDM model. This motivates interest in alternative models that predict enhanced power on cluster scales. We calculate predicted levels and spectra of the superposed emission from groups and clusters of galaxies in $\Lambda$CDM and in two viable alternative non-Gaussian ($\chi^2$) and early dark energy models. The predicted levels of the contribution of clusters to the XRB in the non-Gaussian models exceed the measured level at low energies and levels of the residual XRB in the 2-8 keV band; these particular models are essentially ruled out. Our work demonstrates the diagnostic value of the integrated X-ray emission from clusters, by considering also its dependences on different metallicities, gas and temperature profiles, Galactic absorption, merger scenarios, and on a non-thermal pressure component. We also show that the XRB can be used for a upper limit for the concentration parameter value. Comment: 11 pages, 10 figures, 1 table, accepted to MNRAS
    Monthly Notices of the Royal Astronomical Society 04/2009; DOI:10.1111/j.1365-2966.2009.14882.x · 5.23 Impact Factor
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    M. Shimon, Y. Rephaeli, S. Sadeh, B. Keating
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    ABSTRACT: Mapping CMB polarization is an essential ingredient of current cosmological research. Particularly challenging is the measurement of an extremely weak B-mode polarization that can potentially yield unique insight on inflation. Achieving this objective requires very precise measurements of the secondary polarization components on both large and small angular scales. Scattering of the CMB in galaxy clusters induces several polarization effects whose measurements can probe cluster properties. Perhaps more important are levels of the statistical polarization signals from the population of clusters. Power spectra of five of these polarization components are calculated and compared with the primary polarization spectra. These spectra peak at multipoles $\ell \geq 3000$, and attain levels that are unlikely to appreciably contaminate the primordial polarization signals.
    Monthly Notices of the Royal Astronomical Society 03/2009; DOI:10.1111/j.1365-2966.2009.15407.x · 5.23 Impact Factor
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    ABSTRACT: We present an improved strong-lensing analysis of Cl0024+1654 ($z$=0.39) using deep HST/ACS/NIC3 images, based on 33 multiply-lensed images of 11 background galaxies. These are found with a model that assumes mass approximately traces light, with a low order expansion to allow for flexibility on large scales. The model is constrained initially by the well known 5-image system ($z$=1.675) and refined as new multiply-lensed systems are identified using the model. Photometric redshifts of these new systems are then used to constrain better the mass profile by adopting the standard cosmological relation between redshift and lensing distance. Our model requires only 6 free parameters to describe well all positional and redshift data. The resulting inner mass profile has a slope of $d\log M/d\log r\simeq -0.55$, consistent with new weak-lensing measurements where the data overlap, at $r\simeq200$ kpc/$h_{70}$. The combined profile is well fitted by a high concentration NFW mass profile, $C_{\rm vir}\sim 8.6\pm1.6$, similar to other well studied clusters, but larger than predicted with standard $\Lambda$CDM. A well defined radial critical curve is generated by the model and is clearly observed at $r \simeq 12\arcsec$, outlined by elongated images pointing towards the centre of mass. The relative fluxes of the multiply-lensed images are found to agree well with the modelled magnifications, providing an independent consistency check.
    Monthly Notices of the Royal Astronomical Society 02/2009; DOI:10.1111/j.1365-2966.2009.14899.x · 5.23 Impact Factor

Publication Stats

2k Citations
587.68 Total Impact Points

Institutions

  • 1985–2014
    • Tel Aviv University
      • Department of Physics and Astronomy
      Tell Afif, Tel Aviv, Israel
  • 1991–2011
    • University of California, San Diego
      • Center for Astrophysics and Space Sciences (CASS)
      San Diego, California, United States
  • 2009
    • Stanford University
      • Department of Physics
      Stanford, CA, United States
  • 1988–2006
    • University of California, Berkeley
      • Department of Physics
      Berkeley, California, United States
  • 2005
    • Scuola Internazionale Superiore di Studi Avanzati di Trieste
      Trst, Friuli Venezia Giulia, Italy
  • 2002
    • California State University, Dominguez Hills
      • Department of Physics
      Carson, California, United States
  • 1998–1999
    • University of Padova
      • Department of Physics and Astronomy "Galileo Galilei"
      Padua, Veneto, Italy
  • 1994
    • University of Rome Tor Vergata
      Roma, Latium, Italy
    • Northwestern University
      • Department of Physics and Astronomy
      Evanston, Illinois, United States
  • 1992
    • CSU Mentor
      Long Beach, California, United States