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تسجيل مستخدم جديدNot So Heavy Metals: Black Hole Feedback Enriches The Circumgalactic Medium
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We examine the effects of SMBH feedback on the CGM using a cosmological hydrodynamic simulation citep[{sc Romulus25};][]{Tremmel2017} and a set of four zoom-in `genetically modified Milky Way-mass galaxies sampling different evolutionary paths. By tracing the distribution of metals in the circumgalactic medium (CGM), we show that ion{O}{6} is a sensitive indicator of supermassive black hole (SMBH) feedback. First, we calculate the column densities of ion{O}{6} in simulated Milky Way-mass galaxies and compare them with observations from the COS-Halos Survey. Our simulations show column densities of ion{O}{6} in the CGM consistent with those of COS-Halos star forming and quenched galaxies. These results contrast with those from previous simulation studies which typically underproduce CGM column densities of ion{O}{6}. We determine that a galaxys star formation history and assembly record have little effect on the amount of ion{O}{6} in its CGM. Instead, column densities of ion{O}{6} are closely tied to galaxy halo mass and BH growth history. The set of zoom-in, genetically modified Milky Way-mass galaxies indicates that the SMBH drives highly metal-enriched material out into its host galaxys halo which in turn elevates the column densities of ion{O}{6} in the CGM.
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The circumgalactic medium (CGM) of galaxies serves as a record of the influences of outflows and accretion that drive the evolution of galaxies. Feedback from star formation drives outflows that carry mass and metals away from galaxies to the CGM, wh
ile infall from the intergalactic medium (IGM) is thought to bring in fresh gas to fuel star formation. Such exchanges of matter between IGM-CGM-galaxies have proven critical to producing galaxy scaling relations in cosmological simulations that match observations. However, the nature of these processes, of the physics that drives outflows and accretion, and their evolution with cosmic time are not fully characterized. One approach to constraining these processes is to characterize the metal enrichment of gas around and beyond galaxies. Measurements of the metallicity distribution functions of CGM/IGM gas over cosmic time provide independent tests of cosmological simulations. We have made great progress over the last decade as direct result of a very sensitive, high-resolution space-based UV spectrograph and the rise of ground-based spectroscopic archives. We argue the next transformative leap to track CGM/IGM metals during the epoch of galaxy formation and transformation into quiescent galaxies will require 1) a larger space telescope with an even more sensitive high-resolution spectrograph covering both the far- and near-UV (1,000-3,000 AA); and 2) ground-based archives housing science-ready data.
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