19. Measures of the Galaxy Distribution

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.

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Structure of Neighboring Superclusters: A Quantitative Analysis

Symposium - International Astronomical Union ◽

10.1017/s0074180900039139 ◽

1983 ◽

Vol 104 ◽

pp. 265-271 ◽

Cited By ~ 1

Author(s):

J. Einasto ◽

A. Klypin ◽

S. Shandarin

Keyword(s):

Quantitative Analysis ◽

Numerical Methods ◽

Correlation Analysis ◽

Quantitative Method ◽

Galaxy Distribution ◽

The Galaxy

So far the galaxy correlation analysis was the only quantitative method used to describe the distribution of galaxies in space. Here we consider other numerical methods to treat impersonally various aspects of the galaxy distribution.

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Measuring High‐Order Moments of the Galaxy Distribution from Counts in Cells: The Edgeworth Approximation

The Astrophysical Journal ◽

10.1086/305095 ◽

1998 ◽

Vol 493 (1) ◽

pp. 39-51 ◽

Cited By ~ 35

Author(s):

Rita Seung Jung Kim ◽

Michael A. Strauss

Keyword(s):

High Order ◽

Galaxy Distribution ◽

The Galaxy ◽

Edgeworth Approximation ◽

In Cells

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The evolution of clustering and bias in the galaxy distribution

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.1999.0319 ◽

1999 ◽

Vol 357 (1750) ◽

pp. 133-152 ◽

Cited By ~ 2

Author(s):

J. A. Peacock

Keyword(s):

Galaxy Distribution ◽

The Galaxy

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Survey of the Bootes Void

Symposium - International Astronomical Union ◽

10.1017/s0074180900038961 ◽

1983 ◽

Vol 104 ◽

pp. 197-201

Author(s):

R. P. Kirshner ◽

A. Oemler ◽

P. L. Schechter ◽

S. A. Shectman

Keyword(s):

Radial Velocities ◽

Apparent Magnitude ◽

Velocity Difference ◽

Spherical Volume ◽

Galaxy Distribution ◽

The Galaxy ◽

Small Fields ◽

Close Pairs

Radial velocities have been measured for 231 galaxies chosen by apparent magnitude from 282 small fields spanning the area on the sky thought to contain the Bootes void. The galaxy distribution exhibits a spherical volume 6000 km/s in diameter in which no objects are found. The rms velocity difference of close pairs in our sample is less than 180 km/s.

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