Completing the Hydrogen Census in the Circumgalactic Medium at z~0
| Autor: | Pisano, D. J., Fox, A., French, D., Howk, J. C., Lehner, N., Lockman, F. J., Jones, K. |
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| Rok vydání: | 2019 |
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| Druh dokumentu: | Working Paper |
| Popis: | Over the past decade, Lyman-alpha and metal line absorption observations have established the ubiquity of a gas-rich circumgalactic medium (CGM) around star-forming galaxies at z~0.2 potentially tracing half of the missing baryonic mass within galaxy halos. Unfortunately, these observations only provide a statistical measure of the gas in the CGM and do not constrain the spatial distribution and kinematics of the gas. Furthermore, we have limited sensitivity to Lyman-alpha at z~0 with existing instruments. As such, we remain ignorant of how this gas may flow from the CGM onto the disks of galaxies where it can fuel ongoing star-formation in the present day. Fortunately, 21-cm HI observations with radio telescopes can map HI emission providing both spatial and kinematic information for the CGM in galaxies at z=0. Observations with phased array feeds, radio cameras, on single-dish telescopes yield unmatched surface brightness sensitivity and survey speed. These observations can complete the census of HI in the CGM below N(HI)<10^17 cm^-2 and constrain how gas accretion is proceeding in the local universe, particularly when used in concert with UV absorption line data. Comment: Science white paper for the Astro2020 Decadal Survey, 9 pages, 2 figures |
| Databáze: | arXiv |
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