NIHAO VII: Predictions for the galactic baryon budget in dwarf to Milky Way mass haloes

Abstract

We use the NIHAO galaxy formation simulations to make predictions for the baryonic budget in present day galaxies ranging from dwarf to Milky Way masses. The sample is made of 88 independent high resolution cosmological zoom-in simulations. NIHAO galaxies reproduce key properties of observed galaxies, such as the stellar mass vs halo mass and cold gas vs stellar mass relations. Thus they make plausible predictions for the baryon budget. We present the mass fractions of stars, cold gas ($T<10^4$K), cool gas ($10^4<T<10^5$K), warm-hot gas ($10^5<T<5\times 10^6$K), and hot gas (T$>5\times 10^6$K) inside the virial radius, $R_{200}$. Compared to the predicted baryon mass, using the dark halo mass and the universal baryon fraction, $f_{\mathrm{b}}\equiv {\Omega }_{\mathrm{b}}/{\Omega }_{\mathrm{m}}=0.15$, we find that all of our haloes are missing baryons. The missing mass has been relocated past 2 virial radii, and cool gas dominates the corona at low mass (M${}_{200}<3\times 10^{11}{M}_{\odot }$) while the warm-hot gas dominates at high mass (M${}_{200}>3\times 10^{11}{M}_{\odot }$). Haloes of mass $\sim 10^{10}{M}_{\odot }$ are missing $\sim 90\%$ of their baryons. More massive haloes ($\sim 10^{12}{M}_{\odot }$) retain a higher fraction of their baryons, with $\sim 30\%$ missing, consistent with recent observational estimates. Moreover, these more massive haloes reproduce the observed fraction of cold, warm-hot and hot gas. The fraction of cool gas we predict ($0.11\pm 0.06$) is significantly lower than the observation from COS-HALOs (0.3-0.47), but agrees with the alternative analysis of Stern et al. 2016.

11 pages, 8 figures, 1 table accepted for publication by MNRAS

References in corpus (2)

• On the OVI Abundance in the Circumgalactic Medium of Low-Redshift Galaxies
• NIHAO VIII: Circum-galactic medium and outflows - The puzzles of HI and OVI gas distributions

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• The Cosmic Baryon Partition between the IGM and CGM in the SIMBA Simulations
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• The Baryonic Collapse Efficiency of Galaxy Groups in the RESOLVE and ECO Surveys
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• Probing the link between quenching and morphological evolution
• Clues to the nature of dark matter from first galaxies
• A Dark-Matter Halo Profile allowing a Variable Cusp-Core with Analytic Velocity and Potential