TY - JOUR
T1 - Multiscale probability mapping
T2 - Groups, clusters and an algorithmic search for filaments in SDSS
AU - Smith, Anthony G.
AU - Hopkins, Andrew M.
AU - Hunstead, Richard W.
AU - Pimbblet, Kevin A.
PY - 2012/5
Y1 - 2012/5
N2 - We have developed a multiscale structure identification algorithm for the detection of overdensities in galaxy data that identifies structures having radii within a user-defined range. Our 'multiscale probability mapping' technique combines density estimation with a shape statistic to identify local peaks in the density field. This technique takes advantage of a user-defined range of scale sizes, which are used in constructing a coarse-grained map of the underlying fine-grained galaxy distribution, from which overdense structures are then identified. In this study we have compiled a catalogue of groups and clusters at 0.025 < z < 0.24 based on the Sloan Digital Sky Survey (SDSS), Data Release 7, quantifying their significance and comparing with other catalogues. Most measured velocity dispersions for these structures lie between 50 and 400kms -1. A clear trend of increasing velocity dispersion with radius from 0.2 to 1h -1Mpc is detected, confirming the lack of a sharp division between groups and clusters. A method for quantifying elongation is also developed to measure the elongation of group and cluster environments. By using our group and cluster catalogue as a coarse-grained representation of the galaxy distribution for structure sizes of Mpc, we identify 53 filaments (from an algorithmically derived set of 100 candidates) as elongated unions of groups and clusters at 0.025 < z < 0.13. These filaments have morphologies that are consistent with previous samples studied.
AB - We have developed a multiscale structure identification algorithm for the detection of overdensities in galaxy data that identifies structures having radii within a user-defined range. Our 'multiscale probability mapping' technique combines density estimation with a shape statistic to identify local peaks in the density field. This technique takes advantage of a user-defined range of scale sizes, which are used in constructing a coarse-grained map of the underlying fine-grained galaxy distribution, from which overdense structures are then identified. In this study we have compiled a catalogue of groups and clusters at 0.025 < z < 0.24 based on the Sloan Digital Sky Survey (SDSS), Data Release 7, quantifying their significance and comparing with other catalogues. Most measured velocity dispersions for these structures lie between 50 and 400kms -1. A clear trend of increasing velocity dispersion with radius from 0.2 to 1h -1Mpc is detected, confirming the lack of a sharp division between groups and clusters. A method for quantifying elongation is also developed to measure the elongation of group and cluster environments. By using our group and cluster catalogue as a coarse-grained representation of the galaxy distribution for structure sizes of Mpc, we identify 53 filaments (from an algorithmically derived set of 100 candidates) as elongated unions of groups and clusters at 0.025 < z < 0.13. These filaments have morphologies that are consistent with previous samples studied.
KW - Catalogues
KW - Galaxies: clusters: general
KW - Galaxies: groups: general
KW - Large-scale structure of Universe
KW - Methods: statistical
KW - Surveys
UR - http://www.scopus.com/inward/record.url?scp=84862812261&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2012.20400.x
DO - 10.1111/j.1365-2966.2012.20400.x
M3 - Article
AN - SCOPUS:84862812261
VL - 422
SP - 25
EP - 43
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
SN - 1745-3925
IS - 1
ER -