X-ray emission from hot gas in galaxy groups and clusters in SIMBA
Abstract
We examine X-ray scaling relations for massive haloes ( $M_{500}\gt 10^{12.3}\, \mathrm{M}_\odot$ ) in the SIMBA galaxy formation simulation. The X-ray luminosity, LX versus M500 has power-law slopes ${\approx }\frac{5}{3}$ and ${\approx }\frac{8}{3}$ above and below $10^{13.5} \, \mathrm{M}_{\odot }$ , deviating from the self-similarity increasingly to low masses. TX - M500 is self-similar above this mass, and slightly shallower below it. Comparing SIMBA to observed TX scalings, we find that LX, LX-weighted [Fe/H], and entropies at 0.1R200 (S0.1) and R500 (S500) all match reasonably well. S500 - TX is consistent with self-similar expectations, but S0.1 - TX is shallower at lower TX, suggesting the dominant form of heating moves from gravitational shocks in the outskirts to non-gravitational feedback in the cores of smaller groups. SIMBA matches observations of LX versus central galaxy stellar mass M*, predicting the additional trend that star-forming galaxies have higher LX(M*). Electron density profiles for $M_{500}\gt 10^{14}\, \mathrm{M}_\odot$ haloes show a ∼0.1R200 core, but the core is larger at lower masses. TX are reasonably matched to observations, but entropy profiles are too flat versus observations for intermediate-mass haloes, with Score ≈ 200-400 keV cm2. SIMBA's [Fe/H] profile matches observations in the core but overenriches larger radii. We demonstrate that SIMBA's bipolar jet AGN feedback is most responsible for increasingly evacuating lower-mass haloes, but the profile comparisons suggest this may be too drastic in the inner regions.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2020
- DOI:
- 10.1093/mnras/staa2394
- arXiv:
- arXiv:2003.04115
- Bibcode:
- 2020MNRAS.498.3061R
- Keywords:
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- galaxies: formation;
- galaxies: evolution;
- galaxies: groups: general;
- X-rays: galaxies: clusters;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- doi:10.1093/mnras/staa2394