Upper Limits on the Mass of Cool Gas in the Circumgalactic Medium of Dwarf Galaxies
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Faerman, Yakov Zheng, Yong Oppenheimer, Benjamin D. |
| author_facet | Faerman, Yakov Zheng, Yong Oppenheimer, Benjamin D. |
| contents | We use HI absorption measurements to constrain the amount of cool ($\approx 10^4$ K), photoionized gas in the circumgalactic medium (CGM) of dwarf galaxies with $M_* = 10^{6.5-9.5}~M_\odot$ in the nearby Universe ($z<0.3$). We show analytically that volume-filling gas gives an upper limit on the gas mass needed to reproduce a given HI column density profile. We introduce a power-law density profile for the gas distribution and fit our model to archival HI observations to infer the cool CGM gas mass, $M_{\rm cCGM}$, as a function of halo mass. For volume-filling ($f_V=1$) models, we find $M_{\rm cCGM} = 5 \times 10^8-2 \times 10^9~M_{\odot}$, constituting $\lesssim 10\%$ of the halo baryon budget. For clumpy gas, with $f_V=0.01$, the masses are a factor of $\approx 11$ lower, in agreement with our analytic approximation. Our assumption that the measured HI forms entirely in the cool CGM provides a conservative upper limit on $M_{\rm cCGM}$, and possible contributions from the intergalactic medium or warm/hot CGM will further strengthen our result. We estimate the mass uncertainties due to the range of redshifts in our sample and the unknown gas metallicity to be $\approx 15\%$ and $\approx 10\%$, respectively. Our results show that dwarf galaxies have only $\lesssim 15\%$ of their baryon budget in stars and the cool CGM, with the rest residing in the warm/hot CGM or ejected from the dark matter halos. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_02056 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Upper Limits on the Mass of Cool Gas in the Circumgalactic Medium of Dwarf Galaxies Faerman, Yakov Zheng, Yong Oppenheimer, Benjamin D. Astrophysics of Galaxies We use HI absorption measurements to constrain the amount of cool ($\approx 10^4$ K), photoionized gas in the circumgalactic medium (CGM) of dwarf galaxies with $M_* = 10^{6.5-9.5}~M_\odot$ in the nearby Universe ($z<0.3$). We show analytically that volume-filling gas gives an upper limit on the gas mass needed to reproduce a given HI column density profile. We introduce a power-law density profile for the gas distribution and fit our model to archival HI observations to infer the cool CGM gas mass, $M_{\rm cCGM}$, as a function of halo mass. For volume-filling ($f_V=1$) models, we find $M_{\rm cCGM} = 5 \times 10^8-2 \times 10^9~M_{\odot}$, constituting $\lesssim 10\%$ of the halo baryon budget. For clumpy gas, with $f_V=0.01$, the masses are a factor of $\approx 11$ lower, in agreement with our analytic approximation. Our assumption that the measured HI forms entirely in the cool CGM provides a conservative upper limit on $M_{\rm cCGM}$, and possible contributions from the intergalactic medium or warm/hot CGM will further strengthen our result. We estimate the mass uncertainties due to the range of redshifts in our sample and the unknown gas metallicity to be $\approx 15\%$ and $\approx 10\%$, respectively. Our results show that dwarf galaxies have only $\lesssim 15\%$ of their baryon budget in stars and the cool CGM, with the rest residing in the warm/hot CGM or ejected from the dark matter halos. |
| title | Upper Limits on the Mass of Cool Gas in the Circumgalactic Medium of Dwarf Galaxies |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2501.02056 |