Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userWeak lensing study of Abell 2029
52
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Abell 2029 is one of the most studied clusters due to its proximity (z=0.07), its strong X-ray brightness and its giant cD galaxy which is one of the biggest stellar aggregates we know. We present here the first weak lensing mass reconstruction of this cluster made from a deep I-band image of 28.5x28.5 centered on the cluster cD galaxy. This preliminary result allows us already to show the shape similarities between the cD galaxy and the cluster itself, suggesting that they form actually a single structure. We find a lower estimate of the total mass of 1.8 10^14 h^-1 solar masses within a radius of 0.3 h^-1 Mpc. We finally compute the mass-to-cD-light ratio and its evolution as a function of scale.
rate research
Read More
Aims. The Large Binocular Cameras (LBC) are two twin wide field cameras (FOV ~ 23x 25) mounted at the prime foci of the 8.4m Large Binocular Telescope (LBT). We performed a weak lensing analysis of the z=0.288 cluster Abell 611 on g-band data obtained by the blue-optimized Large Binocular Camera in order to estimate the cluster mass. Methods. Due to the complexity of the PSF of LBC, we decided to use two different approaches, KSB and Shapelets, to measure the shape of background galaxies and to derive the shear signal produced by the cluster. Then we estimated the cluster mass with both aperture densitometry and parametric model fits. Results. The combination of the large aperture of the telescope and the wide field of view allowed us to map a region well beyond the expected virial radius of the cluster and to get a high surface density of background galaxies (23 galaxies/arcmin^2). This made possible to estimate an accurate mass for Abell 611. We find that the mass within 1.5 Mpc is: $(8pm3)times 10^{14} M_odot$ from the aperture mass technique and $(5pm1)times 10^{14} M_odot$ using the model fitting by a NFW mass density profile, for both Shapelets and KSB methods. This analysis demonstrates that LBC is a powerful instrument for weak gravitational lensing studies.
Weak lensing applied to deep optical images of clusters of galaxies provides a powerful tool to reconstruct the distribution of the gravitating mass associated to these structures. We use the shear signal extracted by an analysis of deep exposures of a region centered around the galaxy cluster Abell 209, at redshift z=0.2, to derive both a map of the projected mass distribution and an estimate of the total mass within a characteristic radius. We use a series of deep archival R-band images from CFHT-12k, covering an area of 0.3 deg^2. We determine the shear of background galaxy images using a new implementation of the modified Kaiser-Squires-Broadhurst pipeline for shear determination, which we has been tested against the ``Shear TEsting Program 1 and 2 simulations. We use mass aperture statistics to produce maps of the 2 dimensional density distribution, and parametric fits using both Navarro-Frenk-White (NFW) and singular-isothermal-sphere profiles to constrain the total mass. The projected mass distribution shows a pronounced asymmetry, with an elongated structure extending from the SE to the NW. This is in general agreement with the optical distribution previously found by other authors. A similar elongation was previously detected in the X-ray emission map, and in the distribution of galaxy colours. The circular NFW mass profile fit gives a total mass of M_{200} = 7.7^{+4.3}_{-2.7} 10^{14} solar masses inside the virial radius r_{200} = 1.8pm 0.3 Mpc. The weak lensing profile reinforces the evidence for an elongated structure of Abell 209, as previously suggested by studies of the galaxy distribution and velocities.
We present two weak lensing reconstructions of the nearby ($z_{cl}=0.055$) merging cluster Abell 3667, based on observations taken $sim 1$ year apart under different seeing conditions. This is the lowest redshift cluster with a weak lensing mass reconstruction to date. The reproducibility of features in the two mass maps demonstrate that weak lensing studies of low-redshift clusters are feasible. These data constitute the first results from an X-ray luminosity-selected weak lensing survey of 19 low-redshift ($z< 0.1$) southern clusters.
Galaxy clusters might be sources of TeV gamma rays emitted by high-energy protons and electrons accelerated by large scale structure formation shocks, galactic winds, or active galactic nuclei. Furthermore, gamma rays may be produced in dark matter particle annihilation processes at the cluster cores. We report on observations of the galaxy clusters Perseus and Abell 2029 using the 10 m Whipple Cherenkov telescope during the 2003-2004 and 2004-2005 observing seasons. We apply a two-dimensional analysis technique to scrutinize the clusters for TeV emission. In this paper we first determine flux upper limits on TeV gamma-ray emission from point sources within the clusters. Second, we derive upper limits on the extended cluster emission. We subsequently compare the flux upper limits with EGRET upper limits at 100 MeV and theoretical models. Assuming that the gamma-ray surface brightness profile mimics that of the thermal X-ray emission and that the spectrum of cluster cosmic rays extends all the way from thermal energies to multi-TeV energies with a differential spectral index of -2.1, our results imply that the cosmic ray proton energy density is less than 7.9% of the thermal energy density for the Perseus cluster.
We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 ($z = 0.375$) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 1344 weakly lensed galaxies and 39 multiply-imaged sources comprised of 114 multiple images, including a system of multiply-imaged candidates at $z=7.93 pm 0.02$, to obtain a best-fit mass distribution using the cluster lens modeling code Strong and Weak Lensing United. As the only analysis of A370 using strong and weak lensing constraints from Hubble Frontier Fields data, our method provides an independent check on assumptions in other methods on the mass distribution. Convergence, shear, and magnification maps are made publicly available through the HFF website. We find that the model we produce is similar to models produced by other groups, with some exceptions due to the differences in lensing code methodology. In an effort to study how our total projected mass distribution traces light, we measure the stellar mass density distribution using Spitzer/Infrared Array Camera imaging. Comparing our total mass density to our stellar mass density in a radius of 0.3 Mpc, we find a mean projected stellar to total mass ratio of $langle f* rangle = 0.011 pm 0.003$ (stat.) using the diet Salpeter initial mass function. This value is in general agreement with independent measurements of $langle f* rangle$ in clusters of similar total mass and redshift.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
