http://arxiv.org/abs/1806.02368
The formation and evolution of elliptical galaxies in low-density environments is less clear compared to classical elliptical galaxies in high-density environments. Isolated galaxies are defined as galaxies without massive neighbors within scales of galaxy groups. The impact of environment at several Mpc scales on the their properties has been barely explored. Here we study the role of large-scale environment in 573 isolated elliptical galaxies out to z=0.08. The aim is to explore whether the large-scale environment affects some of their physical properties. We use three environmental estimators of the large-scale structure within a projected radius of 5 Mpc around isolated galaxies: the tidal strength parameter, the projected density eta_k, and the distance to the fifth nearest neighbor galaxy. We find that 80% of galaxies at lower densities correspond to ‘red and dead’ elliptical galaxies. Blue and red galaxies do not tend to be located in different environments according to eta_k. Almost all the isolated ellipticals in the densest large-scale environments are red and/or quenched, where a third of them are low-mass galaxies. We have identified 33 blue, star-forming isolated ellipticals, which are in low density environments. A half of them are star-forming nuclei, whereas 92% of the isolated ellipticals with emission lines corresponds to AGN or composite objects. The large-scale environment is not playing the main role to determine the color and sSFR of isolated elliptical galaxies. The large-scale environment seems to be negligible from a stellar mass scale around 10^10.6 Msun, probably due to the dominant presence of AGN at larger masses. For lower masses, the processes of cooling and infall of gas from large scales are very inefficient in ellipticals. AGN might be also an important ingredient to keep most of the low-mass isolated elliptical galaxies quenched.
I. Lacerna, M. Argudo-Fernández and S. Puertas
Fri, 8 Jun 18
22/51
Comments: 13 pages, 6 figures (10 pages and 4 figures without appendix). Submitted to A&A, comments welcome
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