On the Effect of Environment on Line Emission from the Circumgalactic Medium
Abstract
We measure differences in the emission-line flux from the circumgalactic medium (CGM) of galaxies in different environments. Such differences could be a critical clue in explaining a range of galaxy properties that depend on environment. Using large samples of stacked archival spectra from the Sloan Digital Sky Survey, we find that the Hα + [N II] emission-line flux from the CGM within 50 kpc of ∼L* galaxies is lower both for galaxies that lie within a projected distance of ∼500 kpc from a massive (M * > 1011 M ⊙) galaxy and for galaxies in richer/denser environments. The environmental differences are statistically significant even after we control for galaxy mass and morphology. We interpret these observations as a direct signature of environmentally caused strangulation. We present a simple, heuristic model for the effect of a massive parent galaxy. In this model, the CGM cool gas fraction within 50 kpc is significantly decreased for galaxies that lie within 700 kpc of a massive galaxy, with about 80% of the cool gas removed even when the galaxy is at a distance of 500 kpc from its massive parent. However, we discuss alternative physical causes for the observed behavior and discuss ways forward in addressing open questions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2019
- DOI:
- 10.3847/1538-4357/ab2761
- arXiv:
- arXiv:1906.01643
- Bibcode:
- 2019ApJ...880...28Z
- Keywords:
-
- Galaxy: evolution;
- Galaxy: formation;
- intergalactic medium;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 11 pages, 10 figures