CGM properties in VELA and NIHAO simulations; the OVI ionization mechanism: dependence on redshift, halo mass, and radius

Roca-Fàbrega, S.; Faerman, Yakov; Gnat, Orly; Strawn, Clayton; Ceverino, Daniel; Primack, Joel R.; Macciò, Andrea V.; Dutton, Aaron A.; Prochaska, J. Xavier; Stern, Jonathan

doi:10.1093/mnras/stz063

Cited by 32 publications

(29 citation statements)

References 72 publications

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“…The feedback recipe of the NIHAO simulations results in realistic galaxies across more than two orders of magnitude in halo mass (Wang et al 2015) with baryonic properties matching several key observables of local galaxies (e.g. Obreja et al 2016;Macciò et al 2016;Santos-Santos et al 2018;Roca-Fàbrega et al 2019). Here, we extended the mass resolution of the NIHAO sample roughly a magnitude higher in mass resolution and contrasted our model predictions to observational results obtained for the MW and local massive disk galaxies.…”

Section: Summary and Discussionmentioning

confidence: 89%

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

Buck

Obreja

Macciò

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Simulating thin and extended galactic disks has long been a challenge in computational astrophysics. We introduce the NIHAO-UHD suite of cosmological hydrodynamical simulations of Milky Way mass galaxies and study stellar disk properties such as stellar mass, size and rotation velocity which agree well with observations of the Milky Way and local galaxies. In particular, the simulations reproduce the age-velocity dispersion relation and a multi-component stellar disk as observed for the Milky Way. Half of our galaxies show a double exponential vertical profile, while the others are well described by a single exponential model which we link to the disk merger history. In all cases, mono-age populations follow a single exponential whose scale height varies monotonically with stellar age and radius. The scale length decreases with stellar age while the scale height increases. The general structure of the stellar disks is already set at time of birth as a result of the inside-out and upside-down formation. Subsequent evolution modifies this structure by increasing both the scale length and height of all mono-age populations. Thus, our results put tight constraints on how much dynamical memory stellar disks can retain over cosmological timescales. Our simulations demonstrate that it is possible to form thin galactic disks in cosmological simulations provided there are no significant stellar mergers at low redshifts. Most of the stellar mass is formed in-situ with only a few percent ( ∼ < 5%) brought in by merging satellites at early times. Redshift zero snapshots and halo catalogues are publicly available.

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Section: Summary and Discussionmentioning

confidence: 89%

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

Buck

Obreja

Macciò

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…They used non-equilibrium ionization, and a flickering AGN as an additional ionization source, in zoom simulations otherwise using the EAGLE code and physics. In NIHAO and VELA zoom simulations, Roca-Fàbrega et al (2019) found a roughly equal mix of collisionally and photoionized O vi in z = 0, M 200c = 10 11 -10 12.6 M haloes. Overall, this sup-ports the picture that observed O vi does not have one single origin.…”

Section: Discussion and Comparison To Previous Workmentioning

confidence: 92%

“…A complication with O vi is that the implications of the observations depend on whether the gas is photoionized or collisionally ionized. This is often uncertain from observational data (e.g., Carswell et al 2002;Tripp et al 2008;Werk et al 2014Werk et al , 2016, and simulations find that both are present in the CGM (e.g., Tepper-García et al 2011;Rahmati et al 2016;Oppenheimer et al , 2018Roca-Fàbrega et al 2019). The uncertainty in the ionization mechanism leads to uncertainties in which gas phase is traced, and how much mass is in it.…”

Section: Introductionmentioning

confidence: 99%

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

Wijers

Schaye

Oppenheimer

2020

Monthly Notices of the Royal Astronomical Society

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We use the EAGLE cosmological simulation to study the distribution of baryons, and FUV (O vi), EUV (Ne viii) and X-ray (O vii, O viii, Ne ix, and Fe xvii) line absorbers, around galaxies and haloes of mass $\, \rm {M}_{\rm {200c}}= 10^{11}$–$10^{14.5} \, \rm {M}_{\odot }$ at redshift 0.1. EAGLE predicts that the circumgalactic medium (CGM) contains more metals than the interstellar medium across halo masses. The ions we study here trace the warm-hot, volume-filling phase of the CGM, but are biased towards temperatures corresponding to the collisional ionization peak for each ion, and towards high metallicities. Gas well within the virial radius is mostly collisionally ionized, but around and beyond this radius, and for O vi, photo-ionization becomes significant. When presenting observables we work with column densities, but quantify their relation with equivalent widths by analysing virtual spectra. Virial-temperature collisional ionization equilibrium ion fractions are good predictors of column density trends with halo mass, but underestimate the diversity of ions in haloes. Halo gas dominates the highest column density absorption for X-ray lines, but lower-density gas contributes to strong UV absorption lines from O vi and Ne viii. Of the O vii (O viii) absorbers detectable in an Athena X-IFU blind survey, we find that 41 (56) per cent arise from haloes with $\, \rm {M}_{\rm {200c}}= 10^{12.0 \rm {-}13.5} \, \rm {M}_{\odot }$. We predict that the X-IFU will detect O vii (O viii) in 77 (46) per cent of the sightlines passing $\, \rm {M}_{\star }= 10^{10.5 \rm {-}11.0} \, \rm {M}_{\odot }$ galaxies within $100 \, \rm {pkpc}$ (59 (82) per cent for $\, \rm {M}_{\star }> 10^{11.0} \, \rm {M}_{\odot }$). Hence, the X-IFU will probe covering fractions comparable to those detected with the Cosmic Origins Spectrograph for O vi.

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“…The only clear distinction between clouds in the highest-mass halos and those about lower-mass galaxies is at column densities log N (H I) 16.0, which are essentially absent in the highest-mass galaxies (log M 11.3). The lack of O VI in these halos (see Paper II) also indicates there is little cool gas at very low densities, log n H −4 (e.g., Stern et al 2018;Roca-Fàbrega et al 2019), which would give rise to photoionized O VI. This may imply gas below some critical density is readily evaporated, heated, and ionized to a point where it is not detected in our H I selection, while the higher density gas can survive.…”

Section: Summary and Concluding Remarksmentioning

confidence: 91%

The Red Dead Redemption Survey of Circumgalactic Gas about Massive Galaxies. I. Mass and Metallicity of the Cool Phase

Berg

Howk

Lehner

et al. 2019

ApJ

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We present a search for H I in the circumgalactic medium (CGM) of 21 massive ( log M ∼ 11.4), luminous red galaxies (LRGs) at z ∼ 0.5. Using UV spectroscopy of QSO sightlines projected within 500 kpc (∼R vir ) of these galaxies, we detect H I absorption in 11/21 sightlines, including two partial Lyman limit systems and two Lyman limit systems. The covering factor of log N (H I) ≥ 16.0 gas within the virial radius of these LRGs is f c (ρ ≤ R vir ) = 0.27 +0.11 −0.10 , while for optically-thick gas (log N (−0.07 . Combining this sample of massive galaxies with previous galaxy-selected CGM studies, we find no strong dependence of the H I covering factor on galaxy mass, although star-forming galaxies show marginally higher covering factors. There is no evidence for a critical mass above which dense, cold (T ∼ 10 4 K) gas is suppressed in the CGM of galaxies (spanning stellar masses 9.5 log M 11.8). The metallicity distribution in LRGs is indistinguishable from those found about lower-mass star-forming galaxies, and we find low-metallicity gas with [X/H] ≈ −1.8 (1.5% solar) and below about massive galaxies. About half the cases show super-solar [Fe II/Mg II] abundances as seen previously in cool gas near massive galaxies. While the high-metallicity cold gas seen in LRGs could plausibly result from condensation from a corona, the low-metallicity gas is inconsistent with this interpretation.

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CGM properties in VELA and NIHAO simulations; the OVI ionization mechanism: dependence on redshift, halo mass, and radius

Cited by 32 publications

References 72 publications

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

NIHAO-UHD: The properties of MW-like stellar disks in high resolution cosmological simulations

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

The Red Dead Redemption Survey of Circumgalactic Gas about Massive Galaxies. I. Mass and Metallicity of the Cool Phase

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