Properties of the circumgalactic medium in simulations compared to observations

Author(s)

Machado, R. E. G. ; Tissera, P. B. ; Lima Neto, G. B. ; Sodre, L., Jr.

• Document type: Journal article
• Source: ASTRONOMY & ASTROPHYSICS; v. 609, p. 15-pg., 2018-01-08.

Abstract

Context. Galaxies are surrounded by extended gaseous halos that store significant fractions of chemical elements. These are syntethized by the stellar populations and later ejected into the circumgalactic medium (CGM) by different mechanism, of which supernova feedback is considered one of the most relevant. Aims. We aim to explore the properties of this metal reservoir surrounding star-forming galaxies in a cosmological context aiming to investigate the chemical loop between galaxies and their CGM, and the ability of the subgrid models to reproduce observational results. Methods. Using cosmological hydrodynamical simulations, we have analysed the gas-phase chemical contents of galaxies with stellar masses in the range 10(9)-10(11) M-circle dot. We estimated the fractions of metals stored in the different CGM phases, and the predicted O VI and Si III column densities within the virial radius. Results. We find roughly 10(7) M-circle dot of oxygen in the CGM of simulated galaxies having M-star similar to 10(10) M-circle dot, in fair agreement with the lower limits imposed by observations. The M-oxy is found to correlate with M-star, at odds with current observational trends but in agreement with other numerical results. The estimated profiles of O VI column density reveal a substantial shortage of that ion, whereas Si III, which probes the cool phase, is overpredicted. Nevertheless, the radial dependences of both ions follow the respective observed profiles. The analysis of the relative contributions of both ions from the hot, warm and cool phases suggests that the warm gas (10(5) K < T < 10(6) K) should be more abundant in order to bridge the mismatch with the observations, or alternatively, that more metals should be stored in this gas-phase. These discrepancies provide important information to improve the subgrid physics models. Our findings show clearly the importance of tracking more than one chemical element and the difficulty of simultaneously satisfying the observables that trace the circumgalactic gas at different physical conditions. Additionally, we find that the X-ray coronae around the simulated galaxies have luminosities and temperatures in decent agreement with the available observational estimates. (AU)

• FAPESP's process: 12/00800-4 - The 3-D universe: astrophysics with large galaxy surveys
• Grantee: Laerte Sodré Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 12/20038-0 - Metallicity in galaxy groups: numerical simulations and X-ray observations
• Grantee: Gastão Cesar Bierrenbach Lima Neto
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Multi-user Equipment Program