@article{10902/4840,
year = {2014},
month = {4},
url = {http://hdl.handle.net/10902/4840},
abstract = {Aims. Our goal is to estimate empirically the cosmic variance that affects merger fraction studies based on close pairs for the first time.

Methods. We compute the merger fraction from photometric redshift close pairs with 10 h-1 kpc ≤ rp ≤ 50 h-1 kpc and Δv ≤ 500 km s-1 and measure it in the 48 sub-fields of the ALHAMBRA survey. We study the distribution of the measured merger fractions that follow a log-normal function and estimate the cosmic variance σv as the intrinsic dispersion of the observed distribution. We develop a maximum likelihood estimator to measure a reliable σv and avoid the dispersion due to the observational errors (including the Poisson shot noise term).

Results. The cosmic variance σv of the merger fraction depends mainly on (i) the number density of the populations under study for both the principal (n1) and the companion (n2) galaxy in the close pair and (ii) the probed cosmic volume Vc. We do not find a significant dependence on either the search radius used to define close companions, the redshift, or the physical selection (luminosity or stellar mass) of the samples.

Conclusions. We have estimated the cosmic variance that affects the measurement of the merger fraction by close pairs from observations. We provide a parametrisation of the cosmic variance with n1, n2, and Vc, σv ∝ n1-0.54Vc-0.48 (n_2/n_1)-0.37 . Thanks to this prescription, future merger fraction studies based on close pairs could properly account for the cosmic variance on their results.},
publisher = {EDP Sciences},
publisher = {Astronomy and Astrophysics, vol. 564, art. num. A127 (2014)},
title = {The ALHAMBRA survey: An empirical estimation of the cosmic variance for merger fraction studies based on close pairs},
author = {López-Sanjuan, C. and Cenarro, A. J. and Hernández-Monteagudo, C. and Varela, J. and Molino, A. and Arnalte-Mur, P. and Ascaso, B. and Castander, F. J. and Fernández Soto, Alberto and Huertas-Company, M. and Márquez, I. and Martínez, V. J. and Masegosa, J. and Moles, M. and Povic, M. and López Aguerri, José Alfonso and Alfaro, L. and Aparicio-Villegas, T. and Benítez, N. and Broadhurst, T. and Cabrera-Caño, J. and Cepa, J. and Cerviño, M. and Cristóbal-Hornillos, D. and Olmo, A. del and González Delgado, R. M. and Husillos, C. and Infante, L. and Perea, J. and Prada, F. and Quintana, J. M.},
}