Affiliation:
1. Department of Physics, Visva-Bharati University, Santiniketan, Birbhum, 731235, India
Abstract
ABSTRACT
A non-zero mutual information between morphology of a galaxy and its large-scale environment is known to exist in Sloan Digital Sky Survey (SDSS) upto a few tens of Mpc. It is important to test the statistical significance of these mutual information if any. We propose three different methods to test the statistical significance of these non-zero mutual information and apply them to SDSS and Millennium run simulation. We randomize the morphological information of SDSS galaxies without affecting their spatial distribution and compare the mutual information in the original and randomized data sets. We also divide the galaxy distribution into smaller subcubes and randomly shuffle them many times keeping the morphological information of galaxies intact. We compare the mutual information in the original SDSS data and its shuffled realizations for different shuffling lengths. Using a t-test, we find that a small but statistically significant (at $99.9{{\ \rm per\ cent}}$ confidence level) mutual information between morphology and environment exists upto the entire length-scale probed. We also conduct another experiment using mock data sets from a semi-analytic galaxy catalogue where we assign morphology to galaxies in a controlled manner based on the density at their locations. The experiment clearly demonstrates that mutual information can effectively capture the physical correlations between morphology and environment. Our analysis suggests that physical association between morphology and environment may extend to much larger length-scales than currently believed, and the information theoretic framework presented here can serve as a sensitive and useful probe of the assembly bias and large-scale environmental dependence of galaxy properties.
Funder
University Grants Commission
Science and Engineering Research Board
Alfred P. Sloan Foundation
U.S. Department of Energy
University of Utah
Carnegie Mellon University
Harvard-Smithsonian Center for Astrophysics
Johns Hopkins University
University of Tokyo
Lawrence Berkeley National Laboratory
New Mexico State University
New York University
University of Notre Dame
MCTI
Ohio State University
Pennsylvania State University
Universidad Nacional Autónoma de México
University of Arizona
University of Colorado Boulder
University of Oxford
University of Portsmouth
University of Virginia
University of Washington
Vanderbilt University
Yale University
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
11 articles.
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