Measures of Galaxy Environment – I. What is "Environment"?

Дата и время публикации : 2011-09-28T20:00:13Z

Авторы публикации и институты :
Stuart I. Muldrew
Darren J. Croton
Ramin A. Skibba
Frazer R. Pearce
Hong Bae Ann
Ivan K. Baldry
Sarah Brough
Yun-Young Choi
Christopher J. Conselice
Nicolas B. Cowan
Anna Gallazzi
Meghan E. Gray
Ruth Grützbauch
I-Hui Li
Changbom Park
Sergey V. Pilipenko
Bret J. Podgorzec
Aaron S. G. Robotham
David J. Wilman
Xiaohu Yang
Youcai Zhang
Stefano Zibetti

Ссылка на журнал-издание: 2012, MNRAS, 419, 2670
Коментарии к cтатье: 14 pages, 9 figures, 1 table, published in MNRAS
Первичная категория: astro-ph.CO

Все категории : astro-ph.CO

Краткий обзор статьи: The influence of a galaxy’s environment on its evolution has been studied and compared extensively in the literature, although differing techniques are often used to define environment. Most methods fall into two broad groups: those that use nearest neighbours to probe the underlying density field and those that use fixed apertures. The differences between the two inhibit a clean comparison between analyses and leave open the possibility that, even with the same data, different properties are actually being measured. In this work we apply twenty published environment definitions to a common mock galaxy catalogue constrained to look like the local Universe. We find that nearest neighbour-based measures best probe the internal densities of high-mass haloes, while at low masses the inter-halo separation dominates and acts to smooth out local density variations. The resulting correlation also shows that nearest neighbour galaxy environment is largely independent of dark matter halo mass. Conversely, aperture-based methods that probe super-halo scales accurately identify high-density regions corresponding to high mass haloes. Both methods show how galaxies in dense environments tend to be redder, with the exception of the largest apertures, but these are the strongest at recovering the background dark matter environment. We also warn against using photometric redshifts to define environment in all but the densest regions. When considering environment there are two regimes: the ‘local environment’ internal to a halo best measured with nearest neighbour and ‘large-scale environment’ external to a halo best measured with apertures. This leads to the conclusion that there is no universal environment measure and the most suitable method depends on the scale being probed.

Category: Physics