Browsing by Author "Capasso, R."

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Cluster Cosmology Constraints from the 2500 deg2 SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope
    (2019) Bocquet, S.; Dietrich, J. P.; Schrabback, T.; Bleem, L. E.; Klein, M.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Brodwin, M.; Bulbul, E.; Canning, R. E. A.; Capasso, R.; Carlstrom, J. E.; Chang, C. L.; Chiu, I; Cho, H-M; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Grandis, S.; Gupta, N.; Halverson, N. W.; Hlavacek-Larrondo, J.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Huang, N.; Jones, C.; Khullar, G.; Knox, L.; Kraft, R.; Lee, A. T.; von der Linden, A.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Morris, R. G.; Padin, S.; Patil, S.; Pryke, C.; Rapetti, D.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Strazzullo, V; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.
    We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg(2) SPT-SZ survey. The sample spans the redshift range 0.25 < z < 1.75 and contains 343 clusters with SZ detection significance xi > 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 < z < 1.13 (from Magellan and Hubble Space Telescope) and X-ray measurements of 89 clusters with 0.25 < z < 1.75 (from Chandra). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter E(z) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat nu Lambda CDM model, in which the sum of neutrino masses is a free parameter, we measure Omega(m) = 0.276 +/- 0.047, sigma(8) = 0.781 +/- 0.037, and sigma(8)(Omega(m)/0.3)(0.2) = 0.766 +/- 0.025. The redshift evolutions of the X-ray Y-X-mass and M-gas-mass relations are both consistent with self-similar evolution to within 1 sigma. The mass slope of the Y-X-mass relation shows a 2.3 sigma deviation from self-similarity. Similarly, the mass slope of the M-gas-mass relation is steeper than self-similarity at the 2.5 sigma level. In a nu omega CDM cosmology, we measure the dark energy equation-of-state parameter w = -1.55 +/- 0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z similar to 1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.
  • No Thumbnail Available
    Item
    Gravitational redshifting of galaxies in the SPIDERS cluster catalogue
    (2021) Mpetha, C. T.; Collins, C. A.; Clerc, N.; Finoguenov, A.; Peacock, J. A.; Comparat, J.; Schneider, D.; Capasso, R.; Damsted, S.; Furnell, K.; Merloni, A.; Padilla, N. D.; Saro, A.
    Data from the SPectroscopic IDentification of ERosita Sources (SPIDERS) are searched for a detection of the gravitational redshifting of light from similar to 20 000 galaxies in similar to 2500 galaxy clusters using three definitions of the cluster centre: its Brightest Cluster Galaxy (BCG), the redMaPPer identified Central Galaxy (CG), or the peak of X-ray emission. Distributions of velocity offsets between galaxies and their host cluster's centre, found using observed redshifts, are created. The quantity (Delta) over cap, the average of the radial velocity difference between the cluster members and the cluster systemic velocity, reveals information on the size of a combination of effects on the observed redshift, dominated by gravitational redshifting. The change of (Delta) over cap with radial distance is predicted for SPIDERS galaxies in General Relativity (GR), and f(R) gravity, and compared to the observations. The values of (Delta) over cap = -13.5 +/- 4.7 kms(-1), (Delta) over cap = -12.5 +/- 5.1 kms(-1), and (Delta) over cap = -18.6 +/- 4.8 kms(-1) for the BCG, X-ray, and CG cases, respectively, broadly agree with the literature. There is no significant preference of one gravity theory over another, but all cases give a clear detection (>2.5 sigma) of (Delta) over cap. The BCG centroid is deemed to be the most robust method in this analysis, due to no well-defined central redshift when using an X-ray centroid, and CGs identified by redMaPPer with no associated spectroscopic redshift. For future gravitational redshift studies, an order-of-magnitude more galaxies, similar to 500 000, will be required - a possible feat with the forthcoming Vera C. Rubin Observatory, Euclid and eROSITA.
  • Thumbnail Image
    Item
    SPIDERS : overview of the X-ray galaxy cluster follow-up and the final spectroscopic data release
    (2020) Clerc, N.; Kirkpatrick, C. C.; Finoguenov, A.; Capasso, R.; Comparat, J.; Damsted, S.; Furnell, K.; Kukkola, A. E.; Chitham, J. I.; Padilla, Nelson; Merloni, A.; Salvato, M.; Gueguen, A.; Dwelly, T.; Collins, C.; Saro, A.; Erfanianfar, G.; Schneider, D. P.; Brownstein, J.; Mamon, G. A.; Jullo, E.; Bizyaev, D.
  • Thumbnail Image
    Item
    SPIDERS: an overview of the largest catalogue of spectroscopically confirmed x-ray galaxy clusters
    (2021) Kirkpatrick, C. C.; Clerc, N.; Finoguenov, A.; Damsted, S.; Chitham, J. Ider; Kukkola, A. E.; Gueguen, A.; Furnell, K.; Rykoff, E.; Comparat, J.; Saro, A.; Capasso, R.; Padilla, N.; Erfanianfar, G.; Mamon, G. A.; Collins, C.; Merloni, A.; Brownstein, J. R.; Schneider, D. P.
    SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) project for the identification of X-ray selected galaxy clusters. We present our catalogue of 2740 visually inspected galaxy clusters as part of the SDSS Data Release 16 (DR16). Here we detail the target selection, our methods for validation of the candidate clusters, performance of the survey, the construction of the final sample, and a full description of what is found in the catalogue. Of the sample, the median number of members per cluster is approximately 10, with 818 having 15 or greater. We find that we are capable of validating over 99 per cent of clusters when five redshifts are obtained below z < 0.3 and when nine redshifts are obtained above z > 0.3. We discuss the improvements in this catalogue's identification of cluster using 33 340 redshifts, with Delta Z(phot)/Delta Z(spec) similar to 100, over other photometric and spectroscopic surveys, as well as presenting an update to previous (sigma-L-X) and (sigma-lambda) relations. Finally, we present our cosmological constraints derived using the velocity dispersion function.