Nica, Anna;
Oppenheimer, Benjamin D;
Crain, Robert A;
Bogdán, Ákos;
Davies, Jonathan J;
Forman, William R;
Kraft, Ralph P;
(2022)
Predictions for the X-ray circumgalactic medium of edge-on discs and spheroids.
Monthly Notices of the Royal Astronomical Society
, 517
(2)
pp. 1958-1969.
10.1093/mnras/stac2020.
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Abstract
We investigate how the X-ray circumgalactic medium (CGM) of present-day galaxies depends on galaxy morphology and azimuthal angle using mock observations generated from the EAGLE cosmological hydrodynamic simulation. By creating mock stacks of eROSITA-observed galaxies oriented to be edge-on, we make several observationally-testable predictions for galaxies in the stellar mass range M⋆ = 1010.7 − 11.2 M⊙. The soft X-ray CGM of disc galaxies is between 60 and 100% brighter along the semi-major axis compared to the semi-minor axis, between 10-30 kpc. This azimuthal dependence is a consequence of the hot (T > 106 K) CGM being non-spherical: specifically it is flattened along the minor axis such that denser and more luminous gas resides in the disc plane and co-rotates with the galaxy. Outflows enrich and heat the CGM preferentially perpendicular to the disc, but we do not find an observationally-detectable signature along the semi-minor axis. Spheroidal galaxies have hotter CGMs than disc galaxies related to spheroids residing at higher halos masses, which may be measurable through hardness ratios spanning the 0.2 − 1.5 keV band. While spheroids appear to have brighter CGMs than discs for the selected fixed M⋆ bin, this owes to spheroids having higher stellar and halo masses within that M⋆ bin, and obscures the fact that both simulated populations have similar total CGM luminosities at the exact same M⋆. Discs have brighter emission inside 20 kpc and more steeply declining profiles with radius than spheroids. We predict that the eROSITA 4-year all-sky survey should detect many of the signatures we predict here, although targeted follow-up observations of highly inclined nearby discs after the survey may be necessary to observe some of our azimuthally-dependent predictions.
| Type: | Article |
|---|---|
| Title: | Predictions for the X-ray circumgalactic medium of edge-on discs and spheroids |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stac2020 |
| Publisher version: | https://doi.org/10.1093/mnras/stac2020 |
| Language: | English |
| Additional information: | This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: disc, evolution, formation, methods: numerical, intergalactic medium, X-rays: galaxies |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10153072 |
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