## Detalles de publicación

PP 06011

## Statistics of voids in the 2dF Galaxy Redshift Survey

(1) IAC, (2) IAA, (3) NMSU, (4) AIP

We present a statistical analysis of voids in the 2dF galaxy

redshift survey (2dFGRS). In order to detect the voids, we have

developed two robust algorithms. We define voids as non-overlapping

maximal spheres empty of halos or galaxies with mass or luminosity

above a given one. We search for voids in cosmological $N$-Body

simulations to test the performance of our void finders. We obtain and

analyze the void statistics for several volume-limited samples for the

North Galactic Strip (NGP) and the South Galactic Strip (SGP)

constructed from the 2dFGRS full data release. We find that the

results obtained from the NGP and the SGP are statistically

compatible. From the results of several statistical tests we conclude

that voids are essentially uncorrelated, with at most a mild

anticorrelation and that at the 99.5\% confidence level there is a

dependence of the void number density on redshift. We

develop a technique to correct the distortion caused by the fact that

we use the redshift as the radial coordinate. We calibrate this

technique with mock catalogues and find that the correction might be

of some relevance to carry out accurate inferences from void

statistics. We study the statistics of the galaxies inside nine

nearby voids. We find that galaxies in voids are not randomly distributed:

they form structures like filaments. We also obtain the galaxy number density

profile in voids. This profile follow a similar but steeper trend to that follow by halos

in voids.

redshift survey (2dFGRS). In order to detect the voids, we have

developed two robust algorithms. We define voids as non-overlapping

maximal spheres empty of halos or galaxies with mass or luminosity

above a given one. We search for voids in cosmological $N$-Body

simulations to test the performance of our void finders. We obtain and

analyze the void statistics for several volume-limited samples for the

North Galactic Strip (NGP) and the South Galactic Strip (SGP)

constructed from the 2dFGRS full data release. We find that the

results obtained from the NGP and the SGP are statistically

compatible. From the results of several statistical tests we conclude

that voids are essentially uncorrelated, with at most a mild

anticorrelation and that at the 99.5\% confidence level there is a

dependence of the void number density on redshift. We

develop a technique to correct the distortion caused by the fact that

we use the redshift as the radial coordinate. We calibrate this

technique with mock catalogues and find that the correction might be

of some relevance to carry out accurate inferences from void

statistics. We study the statistics of the galaxies inside nine

nearby voids. We find that galaxies in voids are not randomly distributed:

they form structures like filaments. We also obtain the galaxy number density

profile in voids. This profile follow a similar but steeper trend to that follow by halos

in voids.